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Sample records for subjects performing isometric

  1. Theta power decreases in preparation for voluntary isometric contractions performed with maximal subjective effort.

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    Weiss, T; Sust, M; Beyer, L; Hansen, E; Rost, R; Schmalz, T

    1995-07-07

    In order to find EEG parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were realized in connection with isometric contractions (IMC). IMC were performed with submaximal and maximal subjective effort. Mean spectral power density within the theta band was found as an indicator for maximal subjective effort. The theta power across the parieto-occipital area decreases from rest through movements performed with submaximal force to movements performed with maximal effort. It is argued that this theta decrease possibly reflects a down-regulation of the posterior attention system in order to minimize the influences of external stimuli during the preparation for voluntary IMC performed with maximal subjective effort.

  2. Electrically evoked and voluntary maximal isometric tension in relation to dynamic muscle performance in elderly male subjects, aged 69 years.

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    Davies, C T; White, M J; Young, K

    1983-01-01

    The dynamic performance and electrically evoked mechanical properties of elderly triceps surae muscle have been investigated in 9 men, aged 69 yr. Dynamic performance consisted of cycling on a force bicycle and a vertical jump off two feet from a force platform. The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) were significantly greater (p less than 0.001) by 30 ms and 22 ms and the supramaximal twitch (Pt) and tetanic (20 Hz-P020) tensions and maximal voluntary contraction (MVC) were less by 45 N (-33%), 708 N (-49%), and 899 N (-43%) in the elderly compared with young male control subjects. On the force platform, the height jumped (Ht), maximal force exerted (P), take-off velocity (VT), net impulse (NI) and peak power output (W) were less by 18.6 cm, 173 N, 0.9 ms-1, 52 Ns and 1120 w respectively. Similar differences of power, force and velocity were observed on the force bicycle. The reduction of W in the elderly was associated with the contractile characteristics of the leg muscle. The loss of contractile speed and capacity to to generate force in old people was reflected in their inability to develop power during the performance of a maximal vertical jump and cycling.

  3. Synchronization of muscular oscillations between two subjects during isometric interaction

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    Laura V. Schaefer

    2014-09-01

    Full Text Available Muscles oscillate with a frequency around 10 Hz. But what happens with myofascial oscillations, if two neuromuscular systems interact? The purpose of this study was to examine this question, initially, on the basis of a case study. Oscillations of the triceps brachii muscles of two subjects were determined through mechanomyography (MMG during isometric interaction. The MMG-signals were analyzed concerning the interaction of the two subjects with algorithms of nonlinear dynamics. In this case study it could be shown, that the muscles of both neuromuscular systems also oscillate with the known frequency (here 12 Hz during interaction. Furthermore, both subjects were able to adapt their oscillations against each other. This adjustment induced a significant ( < .05 coherent behavior, which was characterized by a phase shifting of approximately 90°. The authors draw the conclusion, that the complementary neuromuscular partners potentially have the ability of mutual synchronization.

  4. Synchronization of muscular oscillations between two subjects during isometric interaction

    Directory of Open Access Journals (Sweden)

    Laura V. Schaefer

    2014-05-01

    Full Text Available Muscles oscillate with a frequency around 10 Hz. But what happens with myofascial oscillations, if two neuromuscular systems interact? The purpose of this study was to examine this question, initially, on the basis of a case study. Oscillations of the triceps brachii muscles of two subjects were determined through mechanomyography (MMG during isometric interaction. The MMG-signals were analyzed concerning the interaction of the two subjects with algorithms of nonlinear dynamics. In this case study it could be shown, that the muscles of both neuromuscular systems also oscillate with the known frequency (here 12 Hz during interaction. Furthermore, both subjects were able to adapt their oscillations against each other. This adjustment induced a significant ( < .05 coherent behavior, which was characterized by a phase shifting of approximately 90°. The authors draw the conclusion, that the complementary neuromuscular partners potentially have the ability of mutual synchronization.

  5. Influence of Isometric Exercise Training on Quadriceps Muscle Architecture and Strength in Obese Subjects with Knee Osteoarthritis

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    Waleed S Mahmoud

    2017-03-01

    Full Text Available Obese individuals have reduced quadriceps muscle strength relative to body mass that may increase the rate of progression of knee osteoarthritis (OA. The purpose of this study was to evaluate the effects of isometric exercise training on quadriceps muscle architecture and strength in obese subjects with knee osteoarthritis. Methods: Fortyfour obese male subjects aged 40–65 years diagnosed with knee osteoarthritis were randomly assigned into group A (n=32 and group B (n=12. Group A subjects performed a 12-week isometric exercise program. Group B subjects did not participate in any exercise program and maintained their ordinary activities for the same period. Both groups received the same conventional physical therapy program including hot packs and therapeutic ultrasonic. Muscle thickness, pennation angles and fascicle length of the vastus lateralis (VL muscle of the affected knee were measured at rest by B-mode ultrasonography. Maximal voluntary isometric knee extension torque (MVIC of the affected knee was measured using an isokinetic dynamometer. Knee pain and function were evaluated using visual analogue pain scale (VAS and Western Ontario and McMaster Universities Arthritis Index (WOMAC. All variables were evaluated before and the end of the intervention period for both groups. Results: at the end of the program, group A subjects showed significant improvements compared with group B subjects regarding MVIC and muscle architecture parameters (p<0.05. Also, there was significant improvement in post-test VAS and WOMAC scores in group A subjects compared to group B subjects (p<0.05. Conclusion: A 12-week quadriceps isometric training program improves knee pain and quadriceps muscle strength and architecture in obese subjects with knee OA. These results indicate that isometric training should be regarded as a proper exercise intervention for obese patients with knee OA.

  6. EFFICACY OF POST ISOMETRIC RELAXATION VERSUS STATIC STRECHING IN SUBJECTS WITH CHRONIC NON SPECIFIC NECK PAIN

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    P Haritha; Shanthi, C; Madhavi, K.

    2015-01-01

    Background: Neck pain is a common problem within our society. Upper trapezius sternocleidomastoid and the levator scapulae are the most common postural muscles that tends to get shorten leading to restricted neck mobility. There is lack of evidence to allow conclusions to be drawn about the effectiveness of post isometric relaxation when compared with static stretching exercises. The aim is to find out the effectiveness of Post isometric relaxation Versus Static stretching in the subjects wit...

  7. Thigh and calf blood flows after isometric contraction in untrained and trained subjects.

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    Kitamura, K; Shimaoka, M; Matsui, H; Miyamura, M

    1983-01-01

    The present study was undertaken to examine whether or not there were any differences between untrained and trained subjects in the changes of blood flow in the ipsilateral and contralateral lower limbs after isometric exercise. Blood flow of the thigh and calf in both right and left legs were measured simultaneously before and after isometric contraction with mercury-in-silastic strain gauge venous occlusion plethysmography. In the present study, the main pattern of blood flow responses in the active and non-active limbs was strikingly similar in all subjects: a significant fall in blood flow immediately after isometric contraction at a force of about 50% of maximal muscle strength for 15 sec was observed in the non-active lower limbs. Peak blood flow of the exercised thigh in the trained group was significantly higher than that in the untrained ones. From these results, it was suggested that higher blood flow after isometric exercise in the trained subjects may be due to the improvement of degree of vasodilation in the lower limb as a result of physical training.

  8. EFFICACY OF POST ISOMETRIC RELAXATION VERSUS STATIC STRECHING IN SUBJECTS WITH CHRONIC NON SPECIFIC NECK PAIN

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    P.Haritha

    2015-12-01

    Full Text Available Background: Neck pain is a common problem within our society. Upper trapezius sternocleidomastoid and the levator scapulae are the most common postural muscles that tends to get shorten leading to restricted neck mobility. There is lack of evidence to allow conclusions to be drawn about the effectiveness of post isometric relaxation when compared with static stretching exercises. The aim is to find out the effectiveness of Post isometric relaxation Versus Static stretching in the subjects with chronic nonspecific neck pain. To evaluate the effectiveness of post isometric relaxation technique on pain by using Visual analoge scale, range of motion by using Universal Goniometry, and functional disability by using Neck Disability Index in chronic nonspecific neck pain. Methods: A convenient sample of thirty seven subjects was diagnosed with nonspecific neck pain was randomly allocated to one of the two treatment groups on the basis of the inclusion criteria. The experimental group (n=15 received three sessions of post isometric relaxation technique for trapezius, sternocleidomastoid and the levator scapulae and control group (n=15 received the three sessions of static stretching for trapezius, sternocliedomastiod and levator scapulae for four weeks. Results: Non parametric tests demonstrated a statistically significant difference with experimental group showing greater improvement in ROM, VAS, and NDI than the control group and significant difference within the group also. Conclusion: This study concluded and the results reflected that post isometric relaxation technique group had better improvement in reduction of pain, improvement in the range of motion, and increased neck functional activities than the static stretching group.

  9. Relationships between Isometric Force-Time Characteristics and Dynamic Performance

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    Thomas Dos’Santos

    2017-09-01

    Full Text Available The purpose of this study was to explore the relationships between isometric mid-thigh pull (IMTP force-time characteristics (peak force and time-specific force vales (100–250 ms and dynamic performance and compare dynamic performance between stronger and weaker athletes. Forty-three athletes from different sports (rowing, soccer, bicycle motocross, and hockey performed three trials of the squat jump (SJ, countermovement jump (CMJ, and IMTP, and performed a one repetition maximum power clean (PC. Reactive strength index modified (RSImod was also calculated from the CMJ. Statistically significant large correlations between IMTP force-time characteristics and PC (ρ = 0.569–0.674, p < 0.001, and moderate correlations between IMTP force-time characteristics (excluding force at 100 ms and RSImod (ρ = 0.389–0.449, p = 0.013–0.050 were observed. Only force at 250 ms demonstrated a statistically significant moderate correlation with CMJ height (ρ = 0.346, p = 0.016 and no statistically significant associations were observed between IMTP force-time characteristics and SJ height. Stronger athletes (top 10 demonstrated statistically significantly greater CMJ heights, RSImods, and PCs (p ≤ 0.004, g = 1.32–1.89 compared to weaker (bottom 10 athletes, but no differences in SJ height were observed (p = 0.871, g = 0.06. These findings highlight that the ability to apply rapidly high levels of force in short time intervals is integral for PC, CMJ height, and reactive strength.

  10. Correlation between maximum isometric strength variables and specific performance of Brazilian military judokas

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    Michel Moraes Gonçalves

    2017-06-01

    Full Text Available It was our objective to correlate specific performance in the Special Judo Fitness Test (SJFT and the maximum isometric handgrip (HGSMax, scapular traction (STSMax and lumbar traction (LTSMax strength tests in military judo athletes. Twenty-two military athletes from the judo team of the Brazilian Navy Almirante Alexandrino Instruction Centre, with average age of 26.14 ± 3.31 years old, and average body mass of 83.23 ± 14.14 kg participated in the study. Electronic dynamometry tests for HGSMax, STSMax and LTSMax were conducted. Then, after approximately 1 hour-interval, the SJFT protocol was applied. All variables were adjusted to the body mass of the athletes. Pearson correlation coefficient for statistical analysis was used. The results showed moderate negative correlation between the SJFT index and STSMax (r= -0.550, p= 0.008, strong negative correlations between the SJFT index and HGSMax (r= -0.706, p< 0.001, SJFT index and LTSMax (r= -0.721; p= 0.001, besides the correlation between the sum of the three maximum isometric strength tests and the SJFT index (r= -0.786, p< 0.001. This study concludes that negative correlations occur between the SJFT index and maximum isometric handgrip, shoulder and lumbar traction strength and the sum of the three maximum isometric strength tests in military judokas.

  11. An Investigation Into the Relationship Between Maximum Isometric Strength and Vertical Jump Performance.

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    Thomas, Christopher; Jones, Paul A; Rothwell, James; Chiang, Chieh Y; Comfort, Paul

    2015-08-01

    Research has demonstrated a clear relationship between dynamic strength and vertical jump (VJ) performance; however, the relationship of isometric strength and VJ performance has been studied less extensively. The aim of this study was to determine the relationship between isometric strength and performance during the squat jump (SJ) and countermovement jump (CMJ). Twenty-two male collegiate athletes (mean ± SD; age = 21.3 ± 2.9 years; height = 175.63 ± 8.23 cm; body mass = 78.06 ± 10.77 kg) performed isometric midthigh pulls (IMTPs) to assess isometric peak force (IPF), maximum rate of force development, and impulse (IMP) (I100, I200, and I300). Force-time data, collected during the VJs, were used to calculate peak velocity, peak force (PF), peak power (PP), and jump height. Absolute IMTP measures of IMP showed the strongest correlations with VJ PF (r = 0.43-0.64; p ≤ 0.05) and VJ PP (r = 0.38-0.60; p ≤ 0.05). No statistical difference was observed in CMJ height (0.33 ± 0.05 m vs. 0.36 ± 0.05 m; p = 0.19; ES = -0.29) and SJ height performance (0.29 ± 0.06 m vs. 0.33 ± 0.05 m; p = 0.14; ES = -0.34) when comparing stronger to weaker athletes. The results of this study illustrate that absolute IPF and IMP are related to VJ PF and PP but not VJ height. Because stronger athletes did not jump higher than weaker athletes, dynamic strength tests may be more practical methods of assessing the relationships between relative strength levels and dynamic performance in collegiate athletes.

  12. Acute Improvement of Vertical Jump Performance After Isometric Squats Depends on Knee Angle and Vertical Jumping Ability.

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    Tsoukos, Athanasios; Bogdanis, Gregory C; Terzis, Gerasimos; Veligekas, Panagiotis

    2016-08-01

    Tsoukos, A, Bogdanis, GC, Terzis, G, and Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J Strength Cond Res 30(8): 2250-2257, 2016-This study examined the acute effects of maximum isometric squats at 2 different knee angles (90 or 140°) on countermovement jump (CMJ) performance in power athletes. Fourteen national-level male track and field power athletes completed 3 main trials (2 experimental and 1 control) in a randomized and counterbalanced order 1 week apart. Countermovement jump performance was evaluated using a force-plate before and 15 seconds, 3, 6, 9, and 12 minutes after 3 sets of 3 seconds maximum isometric contractions with 1-minute rest in between, from a squat position with knee angle set at 90 or 140°. Countermovement jump performance was improved compared with baseline only in the 140° condition by 3.8 ± 1.2% on the 12th minute of recovery (p = 0.027), whereas there was no change in CMJ height in the 90° condition. In the control condition, there was a decrease in CMJ performance over time, reaching -3.6 ± 1.2% (p = 0.049) after 12 minutes of recovery. To determine the possible effects of baseline jump performance on subsequent CMJ performance, subjects were divided into 2 groups ("high jumpers" and "low jumpers"). The baseline CMJ values of "high jumpers" and "low jumpers" differed significantly (CMJ: 45.1 ± 2.2 vs. 37.1 ± 3.9 cm, respectively, p = 0.001). Countermovement jump was increased only in the "high jumpers" group by 5.4 ± 1.4% (p = 0.001) and 7.4 ± 1.2% (p = 0.001) at the knee angles of 90 and 140°, respectively. This improvement was larger at the 140° angle (p = 0.049). Knee angle during isometric squats and vertical jumping ability are important determinants of the acute CMJ performance increase observed after a conditioning activity.

  13. Relations Between Lower Body Isometric Muscle Force Characteristics and Start Performance in Elite Male Sprint Swimmers

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    Igor Beretić

    2013-12-01

    Full Text Available The aim of the present study was twofold. The first aim was to examine the influence of absolute and relative lower body muscle force on kinematic component which determine the start performance. The second aim was to create multiregressional model which could use as a tool for swimming coaches with the purpose to start performance control and improvement. Twenty seven high-level trained male competitive swimmers all members of the Serbian National Youth and Senior Swimming Team (Age = 21.1 ± 4.3 yrs., Height = 1. 89 ± 0.10 m, Weight = 81.6 ± 8.4 kg, 50m freestyle - long course = 24.36 ± 0.86 s performed two trials of standing leg extensors isometric muscle force testing and three swimming start trials corresponding to 10m distance. The average start time significantly correlated with variables of leg extensors maximum voluntary force (Fmax, r = -0.559, p = 0.002, leg extensors relative muscle voluntary force (Frel, r = -0.727, p < 0.001, leg extensors specific rate of force development (RFD50%, r = -0.338, p = 0.047 and leg extensors relative value of specific rate of force development (RFD50%rel, r = -0.402, p = 0.040. Regression equation for t10m prediction was defined by following variables: maximum voluntary isometric force of leg extensors muscles at absolute and relative level (Fmax and Frel, as well as a specific rate of force development of the same muscle groups (RFD50% and RFD50%rel at absolute and relative level too with 74.4% of explained variance. Contractile abilities indicators of the leg extensors muscles included consideration: Fmax, RFD50%, Frel and RFD50%rel showed significant correlation with swimming start times on 10m. Additionally, the results suggest that swimmers, who possess greater isometric maximum force and specific rate of force development at absolute and relative levels, tend to be able to swim faster on initial 10m swim start perforamnce.

  14. Acute effects of prolonged intermittent low-intensity isometric warm-up schemes on jump, sprint, and agility performance in collegiate soccer players.

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    Pojskić, H; Pagaduan, J C; Babajić, F; Užičanin, E; Muratović, M; Tomljanović, M

    2015-06-01

    The aim of the present study was to compare the effects of different warm-up interventions on jump, sprint and agility performance in collegiate soccer players. Twenty-one healthy male college soccer players (age: 20.14 ± 1.65 years; body height: 179.9 ± 8.34 cm; body mass: 74.4 ± 13.0 kg; % body fat: 9.45 ± 4.8) participated in the study. Subjects underwent four different randomized warm-up protocols separated by at least 48 hours. The warm-up schemes were: 1. no conditioning contraction protocol (NCC); 2. dynamic stretching (DS); 3. prolonged intermittent low-intensity isometric exercise (ST); and, 4. ST with an additional external load equal to 30% of body weight (ST + 30% BW). All interventions were preceded by a general warm-up. Results from one-way repeated measures ANOVA demonstrated a significant difference in countermovement jump (CMJ) at F(3,60) = 10.2, ηρ(2) = 0.337, p agility performance was also observed; F(3, 60) = 24.1, ηρ(2)= 0.546, p agility was observed in DS, ST and ST + 30% BW. In conclusion, a prolonged intermittent low-intensity isometric protocol using bodyweight only showed similar benefits with dynamic stretching in countermovement jump performance. When the same isometric condition with additional load equal to 30% of bodyweight was applied, effects in speed and agility were similar to dynamic stretching.

  15. Hamstrings co-activation in ACL-deficient subjects during isometric whole-leg extensions

    NARCIS (Netherlands)

    Aalbersberg, S.; Kingma, I.; van Dieen, J.H.

    2009-01-01

    It has been reported that anterior cruciate ligament (ACL)-deficient subjects increase the level of hamstrings activation and this has been interpreted as a means to cope with increased anterior tibial laxity in the knee. This study aimed to establish to what extent co-activation strategies in

  16. Factor structure of trunk performance data for healthy subjects.

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    Lee, Y; Kuo, C

    2000-05-01

    To examine the factor structure of various measurements of trunk muscle performance for healthy subjects. A total of 22 performance scores were collected and their univariate and multi-variate relationships were examined. Extensive literature exists on the measurement of trunk performance data and the relationships between measurements but what needs to be collected to realize a true performance score remains unclear. Trunk muscle performance scores of 150 subjects (71 males and 79 females) were obtained on an Isostation B-200 Dynamometer. Twenty-two parameters measuring range of motion, isometric strength, velocity, and endurance on all three planes of motion were collected. The factor structures were constructed using Principal Components Analysis. Clear-cut factor patterns (explained 96.3% of the total variance) suggests that the five-factor structure might be valid and appropriate for this population. The major loading on each factor indicated that: Factor 1 could be labeled as a static strength measure; Factor 2 as velocity; Factor 3 as flexibility; and Factors 4 and 5 as fatigue-resistance. No single mode of measurement can provide a good representation of a total trunk muscle performance. RelevanceFor the realization of trunk muscle performance, clinics have to measure all modes of isometric strength, velocity, range of motion, and endurance. Care must be taken in eliminating any parameter.

  17. The Impact of Chocolate Goat's and Cow's Milk on Postresistance Exercise Endocrine Responses and Isometric Mid-Thigh Pull Performance.

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    Bellar, David; LeBlanc, Nina R; Murphy, Kellie; Moody, Kaitlyn M; Buquet, Gina

    2016-01-01

    The present investigation examined the effects of chocolate cow's and goat's milk on endocrine responses and isometric mid-thigh pull performance post back squat exercise. Twelve college-aged males volunteered to participate and reported to the lab on four occasions. The first visit included anthropometric measurement, one-repetition back squat (1RM), and familiarization with the isometric mid-thigh pull assessment (IMTP). During the subsequent three visits, five sets of eight repetitions of the back squat exercise at 80% of 1RM were performed. For these trials, the participants performed an IMTP and gave a saliva sample prior to, immediately after, 1 hr and 2 hr post exercise. After exercise, a treatment of low-fat chocolate goat's milk (355 ml, 225 kcal), low-fat chocolate cow's milk (355 ml, 225 kcal), or control (water 355 ml, 0 kcal) was given in a counterbalanced order. Saliva samples were analyzed for testosterone, cortisol, and dehydroepiandrosterone (DHEA). Cortisol and DHEA hormone were unaffected by exercise; however, testosterone values did increase significantly post exercise. For IMTP, there was a significant main effect for time (F = 8.41, p = .007) but no treatment or interactions effects. N changes were noted post supplementation for cortisol or DHEA, but testosterone was found to be significantly reduced in both diary treatments compared to control (F = 4.27, p = .022). Based upon these data, it appears that a single treatment of chocolate goat's or cow's milk results in similar endocrine alterations but both fail to enhance postexercise isometric strength following resistance exercise.

  18. Discharge properties of motor units during steady isometric contractions performed with the dorsiflexor muscles

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    Klass, Malgorzata; Duchateau, Jacques; Enoka, Roger M.

    2012-01-01

    The purpose of this study was to record the discharge characteristics of tibialis anterior motor units over a range of target forces and to import these data, along with previously reported observations, into a computational model to compare experimental and simulated measures of torque variability during isometric contractions with the dorsiflexor muscles. The discharge characteristics of 44 motor units were quantified during brief isometric contractions at torques that ranged from recruitment threshold to an average of 22 ± 14.4% maximal voluntary contraction (MVC) torque above recruitment threshold. The minimal [range: 5.8–19.8 pulses per second (pps)] and peak (range: 8.6–37.5 pps) discharge rates of motor units were positively related to the recruitment threshold torque (R2 ≥ 0.266; P torque (R2 = 0.443; P torque increased above recruitment threshold torque. The variability in the simulated torque did not differ from the experimental values once the recruitment range was set to ∼85% MVC torque, and the association between motor twitch contraction times and peak twitch torque was defined as a weak linear association (R2 = 0.096; P muscle depended more on the distributions of mechanical properties than discharge properties across the population of motor units in the tibialis anterior. PMID:22442023

  19. The effect of including a series of isometric conditioning contractions to the rowing warm-up on 1,000-m rowing ergometer time trial performance.

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    Feros, Simon A; Young, Warren B; Rice, Anthony J; Talpey, Scott W

    2012-12-01

    Rowing requires strength, power, and strength-endurance for optimal performance. A rowing-based warm-up could be enhanced by exploiting the postactivation potentiation (PAP) phenomenon, acutely enhancing power output at the beginning of a race where it is needed most. Minimal research has investigated the effects of PAP on events of longer duration (i.e. 1,000-m rowing). The purpose of this research was to investigate the effects of PAP on 1,000-m rowing ergometer performance through the use of 2 different warm-up procedures: (a) a rowing warm-up combined with a series of isometric conditioning contractions, known as the potentiated warm-up (PW), and (b) a rowing warm-up only (NW). The isometric conditioning contractions in the PW were performed by "pulling" an immovable handle on the rowing ergometer, consisting of 5 sets of 5 seconds (2 seconds at submaximal intensity, and 3 seconds at maximal intensity), with a 15-second recovery between sets. The 1,000-m rowing ergometer time trial was performed after each warm-up condition, whereby mean power output, mean stroke rate, and split time were assessed every 100 m. Ten Australian national level rowers served as the subjects and performed both conditions in a counterbalanced order on separate days. The PW reduced 1,000-m time by 0.8% (p > 0.05). The PW improved mean power output by 6.6% (p rowing warm-up enhance short-term rowing ergometer performance (especially at the start of a race) to a greater extent than a rowing warm-up alone.

  20. Acute effects of prolonged intermittent low-intensity isometric warm-up schemes on jump, sprint, and agility performance in collegiate soccer players

    Directory of Open Access Journals (Sweden)

    Haris Pojskic

    2015-02-01

    Full Text Available The aim of the present study was to compare the effects of different warm-up interventions on jump, sprint and agility performance in collegiate soccer players. Twenty-one healthy male college soccer players (age: 20.14 ± 1.65 years; body height: 179.9 ± 8.34 cm; body mass: 74.4 ± 13.0 kg; % body fat: 9.45 ± 4.8 participated in the study. Subjects underwent four different randomized warm-up protocols separated by at least 48 hours. The warm-up schemes were: 1. no conditioning contraction protocol (NCC; 2. dynamic stretching (DS; 3. prolonged intermittent low-intensity isometric exercise (ST; and, 4. ST with an additional external load equal to 30% of body weight (ST + 30% BW. All interventions were preceded by a general warm-up. Results from one-way repeated measures ANOVA demonstrated a significant difference in countermovement jump (CMJ at F(3,60 = 10.2, ηρ 2 = 0.337, p < 0.01. Post hoc analysis revealed a significant difference in CMJ performance in DS when compared to NCC and ST + 30% BW. No significant difference in CMJ was observed between DS and ST. CMJ scores in NCC, ST, and ST + 30% BW were non-significant. There was a significant difference in speed; F(3, 60 = 6.61, ηρ 2 = 0.248, p < 0.01. Post hoc analysis revealed significantly better time in DS than NCC and ST. However, no difference in speed was observed between DS and ST + 30% BW. Similarly, speed was similar in NCC, ST and ST + 30% BW. A significant difference in agility performance was also observed; F(3, 60 = 24.1, ηρ 2 = 0.546, p < 0.01. Post hoc analysis revealed significantly greater performance gains in DS than NCC. No significant difference in agility was observed in DS, ST and ST + 30% BW. In conclusion, a prolonged intermittent low-intensity isometric protocol using bodyweight only showed similar benefits with dynamic stretching in countermovement jump performance. When the same isometric condition with additional load equal to 30% of bodyweight was applied

  1. It wears me out just imagining it! Mental imagery leads to muscle fatigue and diminished performance of isometric exercise.

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    Graham, Jeffrey D; Sonne, Michael W L; Bray, Steven R

    2014-12-01

    The purpose of this study was to investigate the aftereffects of self-generated mental imagery of an effortful task on physical self-control endurance and muscle fatigue. Participants performed two isometric handgrip endurance trials (50% of maximum contraction) separated by either an imagery manipulation or a quiet rest period. The imagery group showed greater negative changes in endurance performance from trial 1 to trial 2 (p=.003, d=0.87) and increased muscle activation at baseline (p=.01, d=0.73) and at 25% (p=.03, d=0.61) of the second endurance trial compared to controls. We conclude that imagined performance of an effortful task depletes self-control strength and contributes to muscle fatigue. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Relationships between rapid isometric torque characteristics and vertical jump performance in division I collegiate American football players: influence of body mass normalization.

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    Thompson, Brennan J; Ryan, Eric D; Sobolewski, Eric J; Smith, Doug B; Akehi, Kazuma; Conchola, Eric C; Buckminster, Tyler

    2013-10-01

    The purpose of the present study was to examine the relationships between absolute and body mass-normalized rapid isometric torque variables and vertical jump (VJ) performance of the leg extensors and flexors in elite National Collegiate Athletic Association Division I Football Bowl Subdivision collegiate American football players. Thirty-one players performed isometric maximal voluntary contractions of the leg extensor and flexor muscle groups and a countermovement VJ. Rate of torque development (RTD) and the contractile impulse (IMPULSE) were determined from 0 to 30, 0 to 50, 0 to 100, and 0 to 200 milliseconds from the onset of muscular contraction. The relationships between absolute and normalized rapid torque variables and VJ performance were assessed using correlation coefficients (r). There were no significant correlations (p > 0.05) observed between the absolute rapid torque variables and VJ performance, except for leg flexion RTD at 0-200 milliseconds (p = 0.024). All normalized rapid torque variables of the leg extensors and flexors were significantly correlated to VJ performance (p ≤ 0.001-0.026). These findings indicated that normalizing rapid torque variables to body mass improves the relationships between isometric rapid torque variables and VJ performance and normalized leg extension and flexion are both similarly related to VJ performance. Strength and conditioning professionals may use these findings in an attempt to identify and monitor dynamic sport performance. Furthermore, future studies examining the relationship between dynamic on the field performances and laboratory-based isometric strength testing may consider including normalized rapid torque variables.

  3. Isometric and dynamic strength and neuromuscular attributes as predictors of vertical jump performance in 11- to 13-year-old male athletes.

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    McKinlay, Brandon John; Wallace, Phillip J; Dotan, Raffy; Long, Devon; Tokuno, Craig; Gabriel, David A; Falk, Bareket

    2017-09-01

    In explosive contractions, neural activation is a major factor in determining the rate of torque development, while the latter is an important determinant of jump performance. However, the contribution of neuromuscular activation and rate of torque development to jump performance in children and youth is unclear. The purpose of this study was to examine the relationships between the rate of neuromuscular activation, peak torque, rate of torque development, and jump performance in young male athletes. Forty-one 12.5 ± 0.5-year-old male soccer players completed explosive, unilateral isometric and dynamic (240°/s) knee extensions (Biodex System III), as well as countermovement-, squat-, and drop-jumps. Peak torque (pT), peak rate of torque development (pRTD), and rate of vastus lateralis activation (Q30) during the isometric and dynamic contractions were examined in relation to attained jump heights. Isometric pT and pRTD were strongly correlated (r = 0.71) but not related to jump performance. Dynamic pT and pRTD, normalized to body mass, were significantly related to jump height in all 3 jumps (r = 0.38-0.66, p jump performance, while isometric contractions are not. These findings have implications in the choice of training and assessment methods for young athletes.

  4. Between-day reliability of electromechanical delay of selected neck muscles during performance of maximal isometric efforts

    Directory of Open Access Journals (Sweden)

    Almosnino Sivan

    2009-09-01

    Full Text Available Abstract Background The purpose of this study was to assess the between-day reliability of the electromechanical delay (EMD of selected neck muscles during the performance of maximal isometric contractions in five different directions. Methods Twenty-one physically active males participated in two testing sessions separated by seven to eight days. Using a custom-made fixed frame dynamometer, cervical force and surface electromyography (EMG were recorded bilaterally from the splenius capitis, upper trapezius and sternocleidomastoid muscles during the performance of efforts in extension, flexion, left and right lateral bending, and protraction. The EMD was extracted using the Teager-Kaiser Energy Operator. Reliability indices calculated for each muscle in each testing direction were: the difference in scores between the two testing sessions and corresponding 95% confidence intervals, the standard error of measurement (SEM and intra-class correlation coefficients (ICC. Results EMD values showed no evidence of systematic difference between the two testing sessions across all muscles and testing directions. The SEM for extension, flexion and lateral bending efforts ranged between 2.5 ms to 4.8 ms, indicating a good level of measurement precision. For protraction, SEM values were higher and considered to be imprecise for research and clinical purposes. ICC values for all muscles across all testing directions ranged from 0.23 to 0.79. Conclusion EMD of selected neck muscles can be measured with sufficient precision for the assessment of neck muscle function in an athletic population in the majority of directions tested.

  5. Muscle Activation Pattern During Isometric Ab Wheel Rollout Exercise in Different Shoulder Angle-Positions

    OpenAIRE

    Marchetti, Paulo Henrique; Schoenfeld, Brad J.; Silva, Josinaldo Jarbas da; Guiselini, Mauro Antonio; Freitas, Fabio Sisconeto de; Pecoraro, Silvio Luiz; Gomes,Willy Andrade; Lopes,Charles Ricardo

    2015-01-01

    OBJECTIVE: To investigate muscle activation of the shoulder extensors and trunk stabilizers by surface electromyography (sEMG) activity during the isometric Ab Wheel Rollout exercise in different shoulder joint positions. METHOD: We recruited 8 young, healthy, resistance trained men (age: 25 ± 3 years, height: 178 ± 5 cm, and total body mass: 81 ± 2 kg). All subjects performed two sets of 10 sec. maximal isometric contractions of the Ab Wheel Rollout exercise keeping the knees fixed on the f...

  6. Subjective performance evaluations and employee careers

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Lange, Fabian; Kriechell, Ben

    Firms commonly use supervisor evaluations to assess the performance of employees who work in complex environments. Doubts persist whether their subjective nature invalidates using these performance measures to learn about careers of individuals and to inform theory in personnel economics. We...... examine personnel data from six large companies and establish how subjective ratings, interpreted as ordinal rankings of employee performances within narrowly defined peer-groups, correlate with objective career outcomes. We find many similarities across firms in how subjective ratings correlate with base...

  7. Subjective performance evaluations and employee careers

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Lange, Fabian; Kriechel, Ben

    Firms commonly use supervisor ratings to evaluate employees when objective performance measures are unavailable. Supervisor ratings are subjective and data containing supervisor ratings typically stem from individual firm level data sets. For both these reasons, doubts persist on how useful...... such data are for evaluating theories in personnel economics and whether findings from such data generalize to the labor force at large. In this paper, we examine personnel data from six large companies and establish how subjective ratings, interpreted as ordinal rankings of employees within narrowly...

  8. Efficacy of Interactive Whiteboard on Psychomotor Skills Achievement of Students in Isometric and Orthographic Projection

    Science.gov (United States)

    Gambari, Isiaka A.; Balogun, Sherifat A.; Alfa, Ahmadu S.

    2014-01-01

    This paper discusses importance of technology education and evidences of declining performance of junior secondary school students in basic technology subject. Potentials on interactive whiteboard (IWB) as one of the new technologies to meet the challenges of the 21st century are also discussed. The efficacy of IWB for teaching Isometric and…

  9. Fast unilateral isometric knee extension torque development and bilateral jump height.

    NARCIS (Netherlands)

    C.J. de Ruiter; M.F. Bobbert; Dr. D.M. van Leeuwen; A.J. Heijblom; A. de Haan

    2006-01-01

    PURPOSE: We hypothesized that the initial rate (first 40 ms) of unilateral knee extensor torque development during a maximally fast isometric contraction would depend on the subjects' ability for fast neural activation and that it would predict bilateral jumping performance. METHODS: Nine males

  10. Fast unilateral isometric knee extension torque development and bilateral jump height.

    NARCIS (Netherlands)

    de Ruiter, C.J.; Leeuwen, D.; Heijblom, A.; Bobbert, M.F.; de Haan, A.

    2006-01-01

    Purpose: We hypothesized that the initial rate (first 40 ms) of unilateral knee extensor torque development during a maximally fast isometric contraction would depend on the subjects' ability for fast neural activation and that it would predict bilateral jumping performance. Methods: Nine males

  11. The influence of athletic status on maximal and rapid isometric torque characteristics and postural balance performance in Division I female soccer athletes and non-athlete controls.

    Science.gov (United States)

    Palmer, Ty B; Hawkey, Matt J; Thiele, Ryan M; Conchola, Eric C; Adams, Bailey M; Akehi, Kazuma; Smith, Doug B; Thompson, Brennan J

    2015-07-01

    The purpose of this study was to examine the effectiveness of maximal and rapid isometric torque characteristics of the hip extensor muscles and postural balance performance to discriminate between female collegiate soccer athletes and non-athlete controls. Ten athletes (mean ± SE: age = 19·20 ± 0·36 year; mass = 62·23 ± 3·12 kg; height = 162·43 ± 1·70 cm) and 10 non-athletes (age = 20·30 ± 0·40 year; mass = 69·64 ± 3·20 kg; height = 163·22 ± 2·10 cm) performed two isometric maximal voluntary contractions (MVCs) of the hip extensor muscles. Peak torque (PT) and absolute and relative rate of torque development (RTD) at early (0-50 ms) and late (100-200 ms) phases of muscle contraction were examined during each MVC. Postural balance was assessed using a commercially designed balance testing device, which provides a measurement of static stability based on sway index (SI). Results indicated that absolute and relative RTD at 0-50 ms (RTD50 and RTD50norm) were greater (P = 0·007 and 0·026), and postural SI was lower (P = 0·022) in the athletes compared with the non-athletes. However, no differences (P = 0·375-0·709) were observed for PT nor absolute and relative RTD at 100-200 ms (RTD100-200 and RTD100-200norm). Significant relationships were also observed between RTD50 and RTD50norm and SI (r = -0·559 and -0·521; P = 0·010 and 0·019). These findings suggest that early rapid torque characteristics of the hip extensor muscles and postural balance performance may be sensitive and effective measures for discriminating between college-aged athletes and non-athletes. Coaches and practitioners may use these findings as performance evaluation tools to help in identifying athletes with both superior early rapid torque and balance performance abilities, which may possibly be an indicator of overall athletic potential. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John

  12. [Reliability and validity of the analysis of hand grip and pinch force in isometric and isokinetic conditions].

    Science.gov (United States)

    Benaglia, P G; Franchignoni, F; Ferriero, G; Zebellin, G; Sartorio, F

    1999-01-01

    Strength measurement of the hand grip is at the core of most protocols of functional assessment of the upper limb and in rehabilitation plays a major role in the analysis of treatment efficacy and patients' occupational ability. The aims of this study were to: a) verify the repeatability of strength measurements made during performance of the hand grip and three types of pinch, carried out under isometric and isokinetic conditions; b) compare maximal isometric strength with the corresponding isokinetic value for each of the manoeuvres studied; c) investigate the correlations between the strength expressed in the different manoeuvres, under both isometric and isokinetic conditions. We studied 14 voluntary subjects over three sessions conducted at 48-hr intervals, employing a computerized isokinetic dynamometer Lido WorkSet equipped with device N(o) 21 for the study of pinch (lateral pinch, pulp pinch, chuck pinch) and device N(o) 52 for the grip study. Isometric contractions resulted stronger than isokinetic ones, and the hand grip was found to be the manoeuvre able to produce most strength. The repeatability of each strength measurement test over the three days was high (Intraclass Correlation Coefficients: 0.89-0.93). Correlations between the isometric and isokinetic performance for each of the manoeuvres examined were always high (Pearson's r coefficients: 0.89-0.95) as were those between the different manoeuvres, whether performed in isometric or isokinetic modality (r: 0.60-0.94).

  13. Subject to Form: Research Interviews, Performative Subjectivity, Professional Development

    Science.gov (United States)

    Sarigianides, Sophia Tatiana

    2010-01-01

    In this dissertation, I analyze teacher, literacy coach and researcher subjectivities in a five-year study of on-site professional development with middle-grade Language Arts teachers in a school designated by its district and state as severely underperforming. Interested in the role of research interviews as both research method and cultural…

  14. Effects of asymmetric dynamic and isometric liftings on strength/force and rating of perceived exertion.

    Science.gov (United States)

    Hattori, Y; Ono, Y; Shimaoka, M; Hiruta, S; Kamijima, M; Shibata, E; Ichihara, G; Ando, S; Villaneuva, M B; Takeuchi, Y

    1996-06-01

    A laboratory study was undertaken to determine the postural and physical characteristics and subjective stress during dynamic lifting of a usual load (10 kg) compared with during isometric lifting. The authors also aimed to clarify the effects of asymmetric lifting on these parameters. The subjects were thirteen male college students. They were asked to lift a box weighing 10 kg. They performed sixteen different lifting tasks from the floor to a height of 71 cm, involving a combination of three independent factors: two lifting modes (isometric lifting and dynamic lifting), four lifting angles in relation to the sagittal plane (sagittal plane, right 45 degree, right 90 degree and left 90 degree planes) and two lifting postures (squat and stoop). For each lifting task, strengths or forces and ground reaction forces were measured. At the end of each task, the authors asked the subjects to rate their perceived exertion (RPE) during lifting at ten sites of the body. Angle factor had a significant effect on isometric strengths and dynamic peak forces. Isometric strengths during the maximum 3 s were highest in lifting in the right 45 degree plane, followed by that in the sagittal plane, while those in the right 90 degree and left 90 degree planes were the lowest. However, peak forces in dynamic lifting were the highest in the lifting in the sagittal plane, followed by that in the right 45 degree plane, while those in the right 90 degree and left 90 degree planes were the lowest. Postural factor had a significant effect on height at peak force, which is higher in squat lifting than in stoop lifting. RPEs for the left arm, the backs and the right whole body in isometric lifting were significantly higher than in dynamic lifting of 10 kg. There were remarkably high RPEs for the ipsilateral thigh to the box in right 90 degree and left 90 degree planes during both isometric and dynamic liftings. Locations of the resultant force consisting of three component forces on the force

  15. Handgrip Maximal Voluntary Isometric Contraction Does Not Correlate with Thenar Motor Unit Number Estimation

    Directory of Open Access Journals (Sweden)

    Arun Aggarwal

    2012-01-01

    Full Text Available In slowly progressive conditions, such as motor neurone disease (MND, 50–80% of motor units may be lost before weakness becomes clinically apparent. Despite this, maximal voluntary isometric contraction (MVIC has been reported as a clinically useful, reliable, and reproducible measure for monitoring disease progression in MND. We performed a study on a group of asymptomatic subjects that showed a lack of correlation between isometric grip strength and thenar MUNE. Motor unit number estimation (MUNE estimates the number of functioning lower motor neurones innervating a muscle or a group of muscles. We used the statistical electrophysiological technique of MUNE to estimate the number of motor units in thenar group of muscles in 69 subjects: 19 asymptomatic Cu, Zn superoxide dismutase 1 (SOD 1 mutation carriers, 34 family controls, and 16 population controls. The Jamar hand dynamometer was used to measure isometric grip strength. This study suggests that MUNE is more sensitive for monitoring disease progression than maximal voluntary isometric contraction (MVIC, as MUNE correlates with the number of functional motor neurones. This supports the observation that patients with substantial chronic denervation can maintain normal muscle twitch tension until 50–80% of motor units are lost and weakness is detectable.

  16. The Validity of Subjective Performance Measures

    DEFF Research Database (Denmark)

    Meier, Kenneth J.; Winter, Søren C.; O'Toole, Laurence J.

    2015-01-01

    Public management studies are increasingly using survey data on managers’ perceptions of performance to measure organizational performance. The perceptual measures are tempting to apply because archival performance data or surveys of target group outcomes and satisfaction are often lacking, costly...... to provide, and are highly policy specific rendering generalization difficult. But are perceptual performance measures valid, and do they generate unbiased findings? We examine these questions in a comparative study of middle managers in schools in Texas and Denmark. The findings are remarkably similar...... the resources it has. Even worse, the use of perceptual performance measures seems to provide biased estimates when examining how management affects performance....

  17. All-day performance variations in normal and narcoleptic subjects.

    Science.gov (United States)

    Godbout, R; Montplaisir, J

    1986-01-01

    This study compared the performance of narcoleptic and control subjects on one psychomotor task, examined the recuperative power of naps in narcoleptic subjects, and evaluated the respective recuperative values of REM and NREM sleep. Ten untreated narcoleptic and eight control subjects repeatedly responded to a choice reaction time task during days with and days without napping. Narcoleptic subjects exhibited low performance levels relative to control subjects on all variables. Napping improved the performance of narcoleptic subjects except for the number of long latency (reaction time greater than 1,000 ms) responses. Finally, performance, particularly on accuracy measures, was better, although not significantly, after NREM naps when compared with REM naps.

  18. Confiabilidade e validade de um dinamômetro isométrico modificado na avaliação do desempenho muscular em indivíduos com reconstrução do ligamento cruzado anterior Reliability and validity of a modified isometric dynamometer in the assessment of muscular performance in individuals with anterior cruciate ligament reconstruction

    Directory of Open Access Journals (Sweden)

    Rodrigo Antunes de Vasconcelos

    2009-06-01

    subjects were invited to participate of the study, being divided into three groups with 20 subjects each: control group (GC, group of individuals with ACL reconstruction with patellar tendon graft (GTP, and group of individuals with ACL reconstruction with hamstrings graft (GTF. All individuals performed isometric tests in the MID, muscular strength deficits collected were subsequently compared to the tests performed on the Biodex System 3 operating in the isometric and isokinetic mode at speeds of 60º/s and 180o/s. Intraclass ICC correlation calculations were done in order to assess MID reliability, specificity, sensitivity and Kappa's consistency coefficient calculations, respectively, for assessing the MID's validity in detecting muscular deficits and intra-and intergroup comparisons when performing the four strength tests using the ANOVA method. RESULTS: The modified isometric dynamometer (MID showed excellent reliability and good validity in the assessment of the performance of the knee extensor and flexor muscles groups. In the comparison between groups, the GTP showed significantly greater deficits as compared to the GTF and GC groups. CONCLUSION: Isometric dynamometers connected to mechanotherapy equipments could be an alternative option to collect data concerning performance deficits of the extensor and flexor muscles groups of the knee in subjects with ACL reconstruction.

  19. Differences between measured and resultant joint moments during isometric contractions at the ankle joint.

    Science.gov (United States)

    Arampatzis, Adamantios; Morey-Klapsing, Gaspar; Karamanidis, Kiros; DeMonte, Gianpiero; Stafilidis, Savvas; Brüggemann, Gert-Peter

    2005-04-01

    The purpose of this study was to examine two hypotheses: (a) during voluntary and electrically induced isometric contractions the moments measured at the dynamometer are different from the resultant moments in the same plane around the ankle joint and (b) at a given resultant moment during electrically induced isometric contractions the ankle angle while loading is different from the ankle angle while unloading. Twenty-seven long distance runners participated in the study. All subjects performed isometric maximal voluntary contractions (MVC) and contractions induced by electrostimulation at four different ankle-knee angle combinations on a Biodex-dynamometer. The kinematics of the leg were recorded using the vicon 624 system with eight cameras operating at 120 Hz. The main findings were: (a) the resultant moment at the ankle joint and the moment measured by the Biodex-dynamometer during isometric contractions are different, (b) during a plantar flexion effort the ankle angle changes significantly, whereas the knee angle shows only small and in most cases not significant changes, and (c) at identical resultant ankle joint moments the ankle angles are different between the loading and the unloading phases. The observed differences may lead to erroneous conclusions concerning the following: (a) diagnostic of muscle architecture, (b) estimation of the moment-ankle angle relationship and (c) estimation of the strain and hysteresis of tendons and aponeuroses.

  20. Subjective performance evaluation and gender discrimination

    NARCIS (Netherlands)

    Maas, V.S.; Torres-Gonzalez, R.

    2011-01-01

    Gender discrimination continues to be a problem in organizations. It is therefore important that organizations use performance evaluation methods that ensure equal opportunities for men and women. This article reports the results of an experiment to investigate whether and, if so, how the gender of

  1. Occupational performance of women subjected to mastectomy

    Directory of Open Access Journals (Sweden)

    Jamylle Silva de Brito

    2014-12-01

    Full Text Available Among the several therapeutic approaches to combat breast cancer, mastectomy is the most feared by women, not only because of its aggressive invasive characteristics to the female body, but also because of its biological, functional, emotional, and social repercussions. The objective of the present study was to outline the occupational performance profile through the description of daily life, productive and leisure activities of women that have undergone mastectomy. This is a descriptive cross-sectional study with 21 women carried out at a school hospital in Recife, Pernambuco state, Brazil, from June to September, 2011. We used a sociodemographic questionnaire and occupational assessment by the Canadian Model of Occupational Performance (CMOP. In the occupational performance evaluation, Productivity was the most compromised area, followed by Leisure. Taking care of the body after mastectomy was not a restraint to the development of the daily-life, productive and leisure activities for the operated women, although some reorganization was needed to maintain a satisfactory performance.

  2. Occupational performance of women subjected to mastectomy

    OpenAIRE

    Jamylle Silva de Brito; Juliana Fonsêca de Queiroz Marcelino

    2014-01-01

    Among the several therapeutic approaches to combat breast cancer, mastectomy is the most feared by women, not only because of its aggressive invasive characteristics to the female body, but also because of its biological, functional, emotional, and social repercussions. The objective of the present study was to outline the occupational performance profile through the description of daily life, productive and leisure activities of women that have undergone mastectomy. This is a descriptive ...

  3. Acute effect of different stretching methods on isometric muscle strength

    Directory of Open Access Journals (Sweden)

    Gabriel Vasconcellos de Lima Costa e Silva

    2014-03-01

    This study investigated the acute effect of static stretching methods (SS and proprioceptive neuromuscular facilitation (PNF on the static muscle strength (SMS. Eleven young male subjects with strength training experience, performed 3 tests with a 48h interval between them, randomly selected, where each one subject carried out all procedures: a hand grip without stretching; b hand grip preceded by static stretching of wrist flexors muscles; c hand grip preceded by PNF stretching of wrist flexors muscles. The Shapiro-Wilk test verified the normality of data, and a one-way ANOVA with repeated measures, followed by Tukey’s post hoc test, evaluated the differences between the groups. The significance was set at p 0.05. In conclusion, both stretching methods had caused negative effects on isometric strength, reducing its levels.

  4. Isometric force production parameters during normal and experimental low back pain conditions

    Directory of Open Access Journals (Sweden)

    Blouin Jean-Sébastien

    2005-02-01

    Full Text Available Abstract Background The control of force and its between-trial variability are often taken as critical determinants of motor performance. Subjects performed isometric trunk flexion and extension forces without and with experiment pain to examine if pain yields changes in the control of trunk forces. The objective of this study is to determine if experimental low back pain modifies trunk isometric force production. Methods Ten control subjects participated in this study. They were required to exert 50 and 75% of their isometric maximal trunk flexion and extension torque. In a learning phase preceding the non painful and painful trials, visual and verbal feedbacks were provided. Then, subjects were asked to perform 10 trials without any feedback. Time to peak torque, time to peak torque variability, peak torque variability as well as constant and absolute error in peak torque were calculated. Time to peak and peak dF/dt were computed to determine if the first peak of dF/dt could predict the peak torque achieved. Results Absolute and constant errors were higher in the presence of a painful electrical stimulation. Furthermore, peak torque variability for the higher level of force was increased with in the presence of experimental pain. The linear regressions between peak dF/dt, time to peak dF/dt and peak torque were similar for both conditions. Experimental low back pain yielded increased absolute and constant errors as well as a greater peak torque variability for the higher levels of force. The control strategy, however, remained the same between the non painful and painful condition. Cutaneous pain affects some isometric force production parameters but modifications of motor control strategies are not implemented spontaneously. Conclusions It is hypothesized that adaptation of motor strategies to low back pain is implemented gradually over time. This would enable LBP patients to perform their daily tasks with presumably less pain and more

  5. Age and Sex Effects on the Active Stiffness of Vastus Intermedius under Isometric Contraction

    Directory of Open Access Journals (Sweden)

    Cong-Zhi Wang

    2017-01-01

    Full Text Available Previously, a novel technique was proposed to quantify the relationship between the muscle stiffness and its nonfatigue contraction intensity. The method extended the measured range of isometric contraction to 100% maximum voluntary contraction (MVC using an ultrasonic shear wave measurement setup. Yet, it has not been revealed how this relationship could be affected by factors like age or sex. To clarify these questions, vastus intermedius (VI stiffness of 40 healthy subjects was assessed under 11 step levels of isometric contraction. The subjects were divided into four groups: young males, young females, elderly males, and elderly females (n=10 for each. In a relaxed state, no significant difference was observed between the male and female subjects (p=0.156 nor between the young and elderly subjects (p=0.221. However, when performing isometric contraction, the VI stiffness of males was found to be significantly higher than that of females at the same level (p<0.001, and that of the young was higher than the elderly (p<0.001. Meanwhile, for two knee joint angles used, the stiffness measured at a 90° knee joint angle was always significantly larger than that measured at 60° (p<0.001. Recognizing the active muscle stiffness of VI contributes to body stability, and these results may provide insight into the age and sex bias in musculoskeletal studies, such as those on fall risks.

  6. Performance pinned down: studying subjectivity and the language of performance

    NARCIS (Netherlands)

    Hoedemaekers, C.; Keegan, A.

    2010-01-01

    We draw on Lacan’s notion of language to study employee subjectivity in a public sector organization (Publica) in the Netherlands. Our main contribution lies in using Lacan’s theorization of language and subjectivity as a basis for a detailed textual analysis of how local organizational discourses

  7. Effect of long-term isometric training on core/torso stiffness.

    Science.gov (United States)

    Lee, Benjamin C Y; McGill, Stuart M

    2015-06-01

    Although core stiffness enhances athletic performance traits, controversy exists regarding the effectiveness of isometric vs. dynamic core training methods. This study aimed to determine whether long-term changes in stiffness can be trained, and if so, what is the most effective method. Twenty-four healthy male subjects (23 ± 3 years; 1.8 ± 0.06 m; 77.5 ± 10.8 kg) were recruited for passive and active stiffness measurements before and after a 6-week core training intervention. Twelve subjects (22 ± 2 years; 1.8 ± 0.08 m; 78.3 ± 12.3 kg) were considered naive to physical and core exercise. The other 12 subjects (24 ± 3 years; 1.8 ± 0.05 m; 76.8 ± 9.7 kg) were Muay Thai athletes (savvy). A repeated-measures design compared core training methods (isometric vs. dynamic, with a control group) and subject training experience (naive vs. savvy) before and after a 6-week training period. Passive stiffness was assessed on a "frictionless" bending apparatus and active stiffness assessed through a quick release mechanism. Passive stiffness increased after the isometric training protocol. Dynamic training produced a smaller effect, and as expected, there was no change in the control group. Active stiffness did not change in any group. Comparisons between subject and training groups did not reveal any interactions. Thus, an isometric training approach was superior in terms of enhancing core stiffness. This is important since increased core stiffness enhances load bearing ability, arrests painful vertebral micromovements, and enhances ballistic distal limb movement. This may explain the efficacy reported for back and knee injury reduction.

  8. The Effect of Long Term Isometric Training on Core/Torso Stiffness.

    Science.gov (United States)

    Lee, Benjamin; McGill, Stuart

    2015-03-23

    While core stiffness enhances athletic performance traits controversy exists regarding the effectiveness of isometric vs dynamic core training methods. This study aimed to determine if long term changes in stiffness can be trained, and if so, what is the most effective method. Twenty four healthy male subjects (23 ± 3 years, 1.8 ± 0.06 m, 77.5 ± 10.8 kg) were recruited for passive and active stiffness measurements before and after a six week core training intervention. Twelve subjects (22 ± 2 years, 1.8 ± 0.08 m, 78.3 ± 12.3 kg) were considered naïve to physical and core exercise. The other twelve subjects (24 ± 3 years, 1.8 ± 0.05 m, 76.8 ± 9.7 kg) were Muay Thai athletes (savvy). A repeated measures design compared core training methods (Isometric vs. Dynamic, with a Control group) and subject training experience (naïve vs. savvy) before and after a six week training period. Passive stiffness was assessed on a 'frictionless' bending apparatus and active stiffness assessed via a quick release mechanism. Passive stiffness increased following the isometric training protocol. Dynamic training produced a smaller effect and as expected there was no change in the Control group. Active stiffness did not change in any group. Comparisons between subject and training groups did not reveal any interactions. Thus, an isometric training approach was superior in terms of enhancing core stiffness. This is important since increased core stiffness enhances load bearing ability, arrests painful vertebral micromovements and enhances ballistic distal limb movement. This may explain the efficacy reported for back and knee injury reduction.

  9. The Effects of a Self-Adapted, Jaw Repositioning Mouthpiece and Jaw Clenching on Muscle Activity during Vertical Jump and Isometric Clean Pull Performance

    Directory of Open Access Journals (Sweden)

    Charles Allen

    2016-07-01

    Full Text Available Purpose: The purpose of this study was to investigate the effects of a self-adapted, jaw repositioning mouthpiece and jaw clenching on muscle activity during the countermovement vertical jump (CMVJ and isometric mid-thigh clean pull (MTCP. Methods:  Thirty-six healthy, recreationally trained males (n=36; age, 23 ± 2.8 years; height, 178.54 ± 9.0 cm; body mass, 83.09 ± 7.8 kg completed maximal CMVJ and MTCP assessments under six experimental conditions:  jaw repositioning mouthpiece plus clenching (MP+C, jaw repositioning mouthpiece with jaw relaxed (MP, traditional mouthguard plus clenching (MG+C, traditional mouthguard with jaw relaxed (MG, no mouthpiece plus clenching (NoMP+C and no mouthpiece with jaw relaxed (NoMP while muscle activity of the dominant leg medial gastrocnemius (G, medial hamstring (H, vastus medialis (VMO, and erector spinae (ES was recorded. Results:  Repeated measures ANOVA revealed no changes in MTCP muscle activation for any mouthpiece or clench condition. Jaw clenching, regardless of mouthpiece condition, significantly improved prime mover muscle activation during CMVJ (p .05. Conclusion:  These findings support jaw clenching as a viable technique to elicit concurrent activation potentiation (CAP of prime mover muscle activity during dynamic but not isometric physical activity. Keywords: jaw repositioning mouthpiece, jaw clenching, concurrent activation potentiation, muscle activation

  10. Subjectivity

    Directory of Open Access Journals (Sweden)

    Jesús Vega Encabo

    2015-11-01

    Full Text Available In this paper, I claim that subjectivity is a way of being that is constituted through a set of practices in which the self is subject to the dangers of fictionalizing and plotting her life and self-image. I examine some ways of becoming subject through narratives and through theatrical performance before others. Through these practices, a real and active subjectivity is revealed, capable of self-knowledge and self-transformation. 

  11. Isometric force production in experienced fighter pilots during +3 Gz centrifuge acceleration.

    Science.gov (United States)

    Guardiera, Simon; Bock, Otmar; Pongratz, Hans; Krause, Wolfgang

    2007-11-01

    Previously, we have shown that naïve subjects produce exaggerated isometric forces when exposed to increased acceleration (+Gz) for the first time. The present study investigates whether +G,-experienced PA-200 Tornado pilots show similar deficits. Experiments were conducted in the stationary (+1 Gz) or rotating (+3 Gz) gondola of a human-rated centrifuge. With their dominant hand, seven pilots produced visually prescribed forces of specific direction and magnitude using an isometric joystick. In practice trials, subjects received continuous visual feedback about their performance, while in test trials they did not. Peak forces during test trials were significantly higher in +3 Gz than in +1 Gz, although this increase of about 25% referring to the +1 Gz value was somewhat smaller in pilots than in nonpilot controls (increase of about 36%). Since pilots' responses were exaggerated in +3 Gz, it seems that frequent exposure to varying +Gz levels is not sufficient for a profound adaptation of force-producing mechanisms to +3 Gz. In consequence, pilots' performance on isometric tasks could be compromised during flight maneuvers in +Gz.

  12. Muscle vibration sustains motor unit firing rate during submaximal isometric fatigue in humans.

    Science.gov (United States)

    Griffin, L; Garland, S J; Ivanova, T; Gossen, E R

    2001-09-15

    1. In keeping with the 'muscular wisdom hypothesis', many studies have documented that the firing rate of the majority of motor units decreased during fatiguing isometric contractions. The present study investigated whether the application of periodic muscle vibration, which strongly activates muscle spindles, would alter the modulation of motor unit firing rate during submaximal fatiguing isometric contractions. 2. Thirty-three motor units from the lateral head of the triceps brachii muscle were recorded from 10 subjects during a sustained isometric 20 % maximal voluntary contraction (MVC) of the elbow extensors. Vibration was interposed on the contraction for 2 s every 10 s. Twenty-two motor units were recorded from the beginning of the fatigue task. The discharge rate of the majority of motor units remained constant (12/22) or increased (4/22) with fatigue. Six motor units demonstrated a reduction in discharge rate that later returned toward initial values; these motor units had higher initial discharge rates than the other 16 motor units. 3. In a second series of experiments, four subjects held a sustained isometric 20 % MVC for 2 min and then vibration was applied as above for the remainder of the contraction. In this case, motor units initially demonstrated a decrease in firing rate that increased after the vibration was applied. Thus muscle spindle disfacilitation of the motoneurone pool may be associated with the decline of motor unit discharge rate observed during the first 2 min of the contraction. 4. In a third set of experiments, seven subjects performed the main experiment on one occasion and repeated the fatigue task without vibration on a second occasion. Neither the endurance time of the fatiguing contraction nor the MVC torque following fatigue was affected by the application of vibration. This finding calls into question the applicability of the muscular wisdom hypothesis to submaximal contractions.

  13. Effect of visual feedback information on isometric contraction of forearm flexor muscles in men and women after ischemic stroke.

    Science.gov (United States)

    Darbutas, Tomas; Juodžbalienė, Vilma; Skurvydas, Albertas; Krutulytė, Gražina; Rimdeikienė, Inesa; Brazaitis, Marius

    2012-01-01

    The aim of this study was to determine the effect of visual feedback information (VFI) on the isometric contraction of the forearm flexor muscles in men and women after an ischemic stroke when doing a physical load at 20% of strength. The study included healthy subjects (n=20) and subjects after ischemic stroke (n=20). The study was conducted in Lithuanian Sports University. The measurements of maximum voluntary strength (MVS) and accurate isometric contraction were performed using an isokinetic dynamometer Biodex System Pro 3. The absolute errors of isometric contraction of the right arm muscles at 20% of MVS were similar in all the groups during the attempt with visual feedback information. The smallest absolute errors of the healthy subjects were 1.42±0.35 Nm when the task was performed with visual feedback and the greatest absolute errors were 4.69±0.95 Nm (P<0.01) while performing the task without visual feedback. Meanwhile, the smallest and greatest absolute errors of the subjects after ischemic stroke were 1.32±0.45 Nm and 5.05±0.63 Nm, respectively, while performing the task without visual feedback (P<0.01). Maximum voluntary strength was greater in all the groups of men. The absolute errors of isometric contractions of the right and left arm muscles tended to increase in both the men and the women when there was no visual feedback information. The women and the men after an ischemic stroke produced greater absolute errors when performing the task with the right and left arm without visual feedback information than the healthy subjects.

  14. Physiological tremor (8-12Hz component) in isometric force control.

    Science.gov (United States)

    Novak, Thomas; Newell, Karl M

    2017-02-22

    The experiment investigated the influence of physiological tremor (8-12Hz band) on the variability of isometric force control as a function of force level and hand dominance. Subjects were instructed to match a constant force level target line on a computer screen and minimize error in a uni-manual isometric finger abduction task at 5%, 25%, 45%, 65%, and 85% of their maximal voluntary contraction (MVC). The experimental protocol was performed independently with the left and right hands in separate blocks of performance. Tremor amplitude was enhanced at an increasing rate with increments of force level and was correlated with both performance outcome (Root mean square error - RMSE) and time-dependent regularity (Sample Entropy) of the force signal. No significant findings in force variability (dispersion or irregularity) were found between the dominant and non-dominant hands. Physiological tremor has a small but direct influence on the dispersion and time dependent structure of the variability of isometric force control but its relative influence on force amplitude decreases with increments of force level. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Isometric knee-extensor torque development and jump height in volleyball players.

    Science.gov (United States)

    de Ruiter, C J; Vermeulen, Gido; Toussaint, Huub M; de Haan, Arnold

    2007-08-01

    The goal of the present study was to determine the contribution of the intrinsic muscle properties and muscle activation of the knee extensors to the maximal rate of unilateral isometric torque development and to relate both factors to maximal bilateral jumping performance in experienced jumpers. On the basis of previous studies, we hypothesized that maximal rate of torque development during maximal effort isometric contractions and jump height would depend on the subjects' ability for maximal muscle activation rather than on the muscle's contractile properties. Eleven male elite volleyball players (20 +/- 2 yr, means +/- SD) performed squat jumps starting from a 120 degrees knee angle (SJ120; full extension = 180 degrees ) and countermovement jumps. In addition, maximal voluntary and electrically evoked unilateral isometric knee-extension torque development (120 degrees angle) was obtained. Torque time integral for the first 40 ms after torque onset (TTI40) and (time to) maximal rate of torque development (MRTD) were calculated. Muscle activation was quantified using surface EMG. Voluntary TTI40 was significantly related to the preceding EMG (r2 = 0.83) and negatively related to the time to MRTD (r2 = 0.64). Voluntary MRTD and TTI40 were not related to their respective values obtained during electrical stimulation (r2 speed. However, unexpectedly, only the latter could predict jump performance in skilled jumpers.

  16. Subjective performance evaluations and reciprocity in principal-agent relations

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher; Walzl, Markus

    2014-01-01

    . In contrast to existing models of reciprocity, we find that agents tend to sanction whenever the feedback of principals is below their subjective self-evaluations even if agents' pay-offs are independent of it. In turn, principals provide more positive feedback (relative to their actual performance assessment......We conduct a laboratory experiment with agents working on, and principals benefiting from, a real effort task in which the agents' performance can only be evaluated subjectively. Principals give subjective performance feedback to agents, and agents have an opportunity to sanction principals...

  17. Relations between subjective evaluations of memory and objective memory performance

    NARCIS (Netherlands)

    Schmidt, I.W; Berg, I.J; Deelman, B.G

    2001-01-01

    Several explanations for the weak relations between subjective memory judgments and objective memory performance were investigated in two groups of normal older adults. Group 1 sampled a general population (mean age 61.6 yr., range 46-891, while Group 2 sampled subjects who were on a waiting Est for

  18. Relative contribution of trunk muscles to the stability of the lumbar spine during isometric exertions.

    Science.gov (United States)

    Cholewicki, Jacek; VanVliet, James J

    2002-02-01

    To compare the relative contribution of various trunk muscles to the stability of the lumbar spine. Quantification of spine stability with a biomechanical model. Modern low back rehabilitation techniques focus on muscles that stabilize the lumbar spine. However, the relative contribution of various trunk muscles to spine stability is currently unknown. Eight male subjects performed isometric exertions in trunk flexion, extension, lateral bending, and axial rotation, and isometric exertions under vertical trunk loading and in a lifting hold. Each isometric trial was repeated three times at 20%, 40%, and 60% of the maximum trunk flexion force or with a load of 0%, 20%, 40%, and 60% of body weight for the latter two exertions. Surface EMG data from 12 major trunk muscles were used in the biomechanical model to estimate stability of the lumbar spine. A simulation of each trial was performed repeatedly with one of the 10 major trunk muscle groups removed from the model. Relative contribution of each muscle to spine stability was significantly affected by the combination of loading magnitude and direction (3-way interaction). None of the removed muscles reduced spine stability by more than 30%. A single muscle cannot be identified as the most important for the stability of the lumbar spine. Rather, spine stability depends on the relative activation of all trunk muscles and other loading variables. This study will improve our understanding of individual trunk muscles' contribution to overall stability of the lumbar spine.

  19. Isometric Tremor Irregularity, Torque Steadiness and Rate of Force Development in Parkinson's Disease

    DEFF Research Database (Denmark)

    Rose, Martin Høyer; Løkkegaard, Annemette; Sonne-Holm, Stig

    2013-01-01

    We investigated lower-extremity isometric tremor Approximate Entropy (irregularity), torque steadiness and rate of force development (RFD) and their associations to muscle activation strategy during isometric knee extensions in patients with Parkinson's disease (PD). Thirteen male patients...... that both knee isometric tremor Approximate Entropy and torque steadiness clearly differentiate between patients with PD and healthy controls. Furthermore, severely compromised RFD was found in patients with PD and was associated with decreased agonist muscle activation....... with idiopathic PD and 15 neurologically healthy matched controls performed isometric maximal contractions (extension/flexion) as well as steady submaximal and powerful isometric knee extensions. The patients with PD showed decreased isometric tremor irregularity. Torque steadiness was reduced in PD...

  20. Isometric exercises reduce temporal summation of pressure pain in humans

    DEFF Research Database (Denmark)

    Vaegter, H B; Handberg, G; Graven-Nielsen, T

    2015-01-01

    BACKGROUND: Aerobic and isometric exercises are known to decrease pain sensitivity. The effect of different types of exercise on central mechanisms such as temporal summation of pain (TSP) is less clear. This study hypothesized that both aerobic and isometric exercises would increase pressure pain...... tolerance (PTT) and reduce TSP with greater effects after higher-intensity exercises. METHODS: One hundred thirty-six healthy subjects (18-65 years; 68 women) participated in two randomized crossover experiments with trials on two different days. PTT and TSP were assessed before and after bicycling...... and a non-exercise condition (experiment 1), and after low- and high-intensity bicycling and low- and high-intensity isometric arm and leg exercises with the dominant arm/leg (experiment 2). PTT and TSP were assessed before and after each exercise condition on the non-dominant arm and leg by computer...

  1. Performance of Pekin ducks subjected to qualitative feed restriction ...

    African Journals Online (AJOL)

    Performance of Pekin ducks subjected to qualitative feed restriction at various ages during the rearing period. Different diets low in lysine were fed to ducklings of various ages in three separate trials to investigate the effect of these diets on bodymass and subsequent reproductive performance. The results showed that when ...

  2. Optimal contracts based on subjective performance evaluations and reciprocity

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher; Walzl, Markus

    2015-01-01

    As demonstrated in a recent laboratory experiment (see Sebald & Walzl, 2014), individuals tend to sanction others who subjectively evaluate their performance whenever this assessment falls short of the individuals’ self-evaluation. Interestingly, this is the case even if the individuals’ earnings...... are unaffected by the subjective performance appraisal. Hence, performance feedback which falls short of agents’ self- evaluations can be interpreted as an unkind act that triggers a negatively reciprocal response not only if the assessment determines agents’ earnings but also when it lacks monetary consequences...

  3. Differences between measured and resultant joint moments during voluntary and artificially elicited isometric knee extension contractions.

    Science.gov (United States)

    Arampatzis, Adamantios; Karamanidis, Kiros; De Monte, Gianpiero; Stafilidis, Savvas; Morey-Klapsing, Gaspar; Brüggemann, Gert-Peter

    2004-03-01

    Examine two hypotheses: (a) during isometric knee extension contractions the moment measured at the dynamometer is different from the resultant moment in the same plane around the knee joint and (b) during isometric contractions, at the same given resultant moment the knee angle while loading is different from the knee angle while unloading. Comparative study in which the geometrical and the kinetic differences between joint and dynamometer were determined. It is usually assumed that the moment measured by the dynamometer is equivalent to the resultant joint moment. The non-rigidity of the dynamometer-leg system can influence the equivalence of these two moments. Twenty seven subjects performed isometric maximal knee extension contractions and contractions induced by electrostimulation on a dynamometer. The kinematics of the leg were recorded using 8 cameras (120 Hz). The resultant moment at the knee joint and the moment measured by the dynamometer are different. During a knee extension effort the knee angle changes significantly. At identical resultant knee joint moments the knee angles are different when comparing the loading and the unloading phases. The differences between the measured and the resultant joint moments might influence the estimation of parameters as: muscle forces, moment-angle relationship and strain and hysteresis of tendons and aponeuroses. Torque dynamometers have been often used to estimate muscle forces, to examine neuromuscular processes and to determine the mechanical properties of tendons and aponeuroses.

  4. Leg dominancy in relation to fast isometric torque production and squat jump height

    NARCIS (Netherlands)

    de Ruiter, C.J.; de Korte, A.; Schreven, S.; de Haan, A.

    2010-01-01

    We hypothesized that maximal unilateral isometric knee extensor torque, the rate of torque development during maximally fast isometric contractions and unilateral squat jump performance would be better with the dominant than non-dominant leg. Limb dominancy was established using the step up, balance

  5. Descending pain modulation and its interaction with peripheral sensitization following sustained isometric muscle contraction in fibromyalgia

    DEFF Research Database (Denmark)

    Ge, H-Y; Nie, Hongling; Graven-Nielsen, Thomas

    2012-01-01

    OBJECTIVE: Sustained isometric muscle contraction (fatiguing contraction) recruits segmental and/or extrasegmental descending inhibition in healthy subjects but not in fibromyalgia (FM). We hypothesized that fatiguing contraction may shift descending pain modulation from inhibition towards...

  6. Performance, Pinned Down: A Lacanian Analysis of Subjectivity at Work

    NARCIS (Netherlands)

    C.M.W. Hoedemaekers (Casper)

    2008-01-01

    textabstractThis study seeks to create an account of how the performing subject comes into being within a specific organizational context. It looks at some of the ways in which managerial practices impact upon the selfhood of employees by means of the language in which they are couched. Drawing

  7. Development of isometric force and force control in children

    NARCIS (Netherlands)

    Smits-Engelsman, B.C.M.; Westenberg, Y.; Duysens, J.E.J.

    2004-01-01

    Fifty-six children between 5 and 12 years of age and 15 adults performed a task (pressing on a lever with the index finger of the preferred hand), in which a force had to be maintained constant at five levels with on-line visual feedback. Since this is a simple isometric task, the hypothesis is that

  8. Development of isometric force and force control in children.

    NARCIS (Netherlands)

    Smits-Engelsman, B.C.M.; Westenberg, Y.; Duysens, J.E.J.

    2003-01-01

    Fifty-six children between 5 and 12 years of age and 15 adults performed a task (pressing on a lever with the index finger of the preferred hand), in which a force had to be maintained constant at five levels with on-line visual feedback. Since this is a simple isometric task, the hypothesis is that

  9. Comparative effects of pilates and isometric exercises on pain ...

    African Journals Online (AJOL)

    Objectives: Knee osteoarthritis is the most common disease of the knee joint and a growing public health problem with physical disability, preventing performance of daily activities. The purpose of this study was to compare the effect of isometric and Pilates exercise on pain, functional disability and range of motion in ...

  10. ISOMETRIC EXERCISE AND ITS EFFECT ON BLOOD PRESSURE AND HEART RATE, BEFORE AND AFTER TRAINING IN YOUNG HEALTHY MALES

    Directory of Open Access Journals (Sweden)

    Mohammed

    2015-05-01

    Full Text Available INTRODUCTION: Isometric exercise is a normal part of everyday activities and many occupational tasks. Preventive services are important as they give physicians an opportunity and responsibility to promote regular physical activity, reduc e high blood pressure, and help in weight control. Physical inactivity is recognized as a risk factor for coronary artery disease. Regular aerobic physical activity increases exercise capacity and plays a role in both primary and secondary prevention of ca rdiovascular disease. OBJECTIVE: To assess the effects of isometric handgrip training on Blood pressure and Heart rate in healthy young males in the age group of 18 - 22 years. MATERIALS AND METHOD : Study subjects consisted of 30 healthy adult males in the age group of 18 - 22 yrs. Age and sex matched adults who were not active in sports or in physical activities constituted the control group (n=30. Blood pressure and heart rate were recorded and eval uated after a defined protocol of handgrip sustained static (isometric contractions performed with the handgrip dynamometer at Rest and Post Exercise. BP and HR were recorded with the help of automated blood pressure monitor and power lab 8/30 series inst rument available in the Department of Physiology , Navodaya Medical college, Raichur. RESULTS: There was no change in Resting Blood pressure and Heart rate between the subject and control group before the training sessions. There was significant decrease in resting Blood pressure and Heart rate in trained subject group when compared to untrained control group after 5 weeks of training sessions. CONCLUSION : Isometric hand grip training is effective in lowering arterial pressure in normotensive subjects. Isome tric training may be an effective intervention in the prevention and treatment of hypertension

  11. Comparison of the Relationship between Lying and Standing Ultrasonography Measures of Muscle Morphology with Isometric and Dynamic Force Production Capabilities

    Directory of Open Access Journals (Sweden)

    John P. Wagle

    2017-11-01

    Full Text Available The purpose of the current study was (1 to examine the differences between standing and lying measures of vastus lateralis (VL, muscle thickness (MT, pennation angle (PA, and cross-sectional area (CSA using ultrasonography; and (2 to explore the relationships between lying and standing measures with isometric and dynamic assessments of force production—specifically peak force, rate of force development (RFD, impulse, and one-repetition maximum back squat. Fourteen resistance-trained subjects (age = 26.8 ± 4.0 years, height = 181.4 ± 6.0 cm, body mass = 89.8 ± 10.7 kg, back squat to body mass ratio = 1.84 ± 0.34 agreed to participate. Lying and standing ultrasonography images of the right VL were collected following 48 hours of rest. Isometric squat assessments followed ultrasonography, and were performed on force platforms with data used to determine isometric peak force (IPF, as well as RFD and impulse at various time points. Forty-eight hours later, one-repetition maximum back squats were performed by each subject. Paired-samples t-tests revealed statistically significant differences between standing and lying measurements of MT (p < 0.001, PA (p < 0.001, and CSA (p ≤ 0.05, with standing values larger in all cases. Further, standing measures were correlated more strongly and abundantly to isometric and dynamic performance. These results suggest that if practitioners intend to gain insight into strength-power potential based on ultrasonography measurements, performing the measurement collection with the athlete in a standing posture may be preferred.

  12. Monitoring elbow isometric contraction by novel wearable fabric sensing device

    Science.gov (United States)

    Wang, Xi; Tao, Xiaoming; So, Raymond C. H.; Shu, Lin; Yang, Bao; Li, Ying

    2016-12-01

    Fabric-based wearable technology is highly desirable in sports, as it is light, flexible, soft, and comfortable with little interference to normal sport activities. It can provide accurate information on the in situ deformation of muscles in a continuous and wireless manner. During elbow flexion in isometric contraction, upper arm circumference increases with the contraction of elbow flexors, and it is possible to monitor the muscles’ contraction by limb circumferential strains. This paper presents a new wireless wearable anthropometric monitoring device made from fabric strain sensors for the human upper arm. The materials, structural design and calibration of the device are presented. Using an isokinetic testing system (Biodex3®) and the fabric monitoring device simultaneously, in situ measurements were carried out on elbow flexors in isometric contraction mode with ten subjects for a set of positions. Correlations between the measured values of limb circumferential strain and normalized torque were examined, and a linear relationship was found during isometric contraction. The average correlation coefficient between them is 0.938 ± 0.050. This wearable anthropometric device thus provides a useful index, the limb circumferential strain, for upper arm muscle contraction in isometric mode.

  13. Association of Chronic Subjective Tinnitus with Neuro- Cognitive Performance.

    Science.gov (United States)

    Gudwani, Sunita; Munjal, Sanjay K; Panda, Naresh K; Kohli, Adarsh

    2017-12-01

    Chronic subjective tinnitus is associated with cognitive disruptions affecting perception, thinking, language, reasoning, problem solving, memory, visual tasks (reading) and attention. To evaluate existence of any association between tinnitus parameters and neuropsychological performance to explain cognitive processing. Study design was prospective, consisting 25 patients with idiopathic chronic subjective tinnitus and gave informed consent before planning their treatment. Neuropsychological profile included (i) performance on verbal information, comprehension, arithmetic and digit span; (ii) non-verbal performance for visual pattern completion analogies; (iii) memory performance for long-term, recent, delayed-recall, immediate-recall, verbal-retention, visualretention, visual recognition; (iv) reception, interpretation and execution for visual motor gestalt. Correlation between tinnitus onset duration/ loudness perception with neuropsychological profile was assessed by calculating Spearman's coefficient. Findings suggest that tinnitus may interfere with cognitive processing especially performance on digit span, verbal comprehension, mental balance, attention & concentration, immediate recall, visual recognition and visual-motor gestalt subtests. Negative correlation between neurocognitive tasks with tinnitus loudness and onset duration indicated their association. Positive correlation between tinnitus and visual-motor gestalt performance indicated the brain dysfunction. Tinnitus association with non-auditory processing of verbal, visual and visuo-spatial information suggested neuroplastic changes that need to be targeted in cognitive rehabilitation.

  14. Which one Enhances Muscular Performance in ACL Reconstructed Subjects

    Science.gov (United States)

    Harput, Gulcan; Ulusoy, Burak; Atay, Ahmet Ozgur; Baltacı, Gul

    2014-01-01

    Objectives: The aim of this study was to investigate the effects of functional knee brace and kinesiotaping on muscular performance in anterior cruciate ligament reconstructed subjects who reached return to sport phase of the rehabilitation. Methods: Twenty (17 males, 3 females, Age: 24.7±7.1 years, Body weight: 74.4±12.0 kg, Height: 177.9±6.5 cm, BMI: 23.9±3.6 kg/m2) subjects who underwent anterior cruciate ligament reconstruction by using hamstring tendon auto graft were included in this study. When the subjects reached the return to sports phase of rehabilitation which was 6th months after surgery, knee muscle strength, jump performance and balance tests were performed 3 times: bare, with knee brace and with kinesio taping. The order of the tests were randomized to eliminate the effects of fatigue and motor learning. Quadriceps and hamstring muscle strength was measured on an isokinetic dynamometer at 180 °/s and 60°/s angular velocities. Vertical Jump (VJ) and One Leg Hop Tests (OLHT) were used to assess jump performance. Star Excursion Balance Test (SEBT) with anterior, posteromedial and posterolateral reach distance was used to assess the dynamic balance. When all tests were performed, the subjects were asked under which test condition they felt more confident. Repeated measures of ANOVA was used to analyze the difference among three test conditions (bare, kinesiotaping, knee brace). Bonferroni post hoc test was used for pairwise comparison. Results: SEBT posteromedial (PM)and posterolateral (PL) reach distances were found significantly different among three test conditions(PM: F(2,38)=3.42,p=0.04), PL: F(2,38)=4.37,p=0.02). Kinesiotaping increased posteromedial reach distance (p=0.03). On the other hand, brace decreased posterolateral reach distance (p=0.04). VJ and OLHT performance were also found significantly different between three test conditions (VJ: F (2,38)=3.44,p=0.04, OLHT: (F(2,38)=4.04,p=0.02). Kinesio taping increased one leg hop distance

  15. Evaluation of electromyographic activity and heart rate responses to isometric exercise. The role played by muscular mass and type

    Directory of Open Access Journals (Sweden)

    E. Silva

    1999-01-01

    Full Text Available The purpose of the present study was to examine the relationship between the electromyographic (EMG activity and heart rate (HR responses induced by isometric exercise performed by knee extension (KE and flexion (KF in men. Fifteen healthy male subjects, 21 ± 1.3 years (mean ± SD, were submitted to KE and KF isometric exercise tests at 100% of maximal voluntary contraction (MVC. The exercises were performed with one leg (right or left and with two legs simultaneously, for 10 s in the sitting position with the hip and knee flexed at 90o. EMG activity (root mean square values and HR (beats/min were recorded simultaneously both at rest and throughout the sustained contraction. The HR responses to isometric exercise in KE and KF were similar when performed with one and two legs. However, the HR increase was always significantly higher in KE than KF (P0.05 and KF (r = 0.15, P>0.05 contractions were not significant. These results suggest that the predominant mechanism responsible for the larger increase in HR response to KE as compared to KF in our study could be dependent on qualitative and quantitative differences in the fiber type composition found in each muscle group. This mechanism seems to demand a higher activation of motor units with a corresponding increase in central command to the cardiovascular centers that modulate HR control.

  16. Ethographic ubiquity: original fake, expanded codex, transurban subject, performative doll

    Directory of Open Access Journals (Sweden)

    Massimo Canevacci

    2012-12-01

    Full Text Available My essay presents the emerging of fake as a concept that does not mean false, but a post-dualistic mix of false/truth. The relation between digital culture and ubiquitous subjectivity is fundamental during its process; in the same way, the relation between aura and reproducibility cannot be determined dialectically as Benjamin did. Digital auratic reproducibility is the contemporary context and communicational metropolis is characterized by spontaneous and public performance: so, my conclusion is an analysis of some “living” doll and their uncanny presence.

  17. An opportunity cost model of subjective effort and task performance.

    Science.gov (United States)

    Kurzban, Robert; Duckworth, Angela; Kable, Joseph W; Myers, Justus

    2013-12-01

    Why does performing certain tasks cause the aversive experience of mental effort and concomitant deterioration in task performance? One explanation posits a physical resource that is depleted over time. We propose an alternative explanation that centers on mental representations of the costs and benefits associated with task performance. Specifically, certain computational mechanisms, especially those associated with executive function, can be deployed for only a limited number of simultaneous tasks at any given moment. Consequently, the deployment of these computational mechanisms carries an opportunity cost--that is, the next-best use to which these systems might be put. We argue that the phenomenology of effort can be understood as the felt output of these cost/benefit computations. In turn, the subjective experience of effort motivates reduced deployment of these computational mechanisms in the service of the present task. These opportunity cost representations, then, together with other cost/benefit calculations, determine effort expended and, everything else equal, result in performance reductions. In making our case for this position, we review alternative explanations for both the phenomenology of effort associated with these tasks and for performance reductions over time. Likewise, we review the broad range of relevant empirical results from across sub-disciplines, especially psychology and neuroscience. We hope that our proposal will help to build links among the diverse fields that have been addressing similar questions from different perspectives, and we emphasize ways in which alternative models might be empirically distinguished.

  18. Análise da translação anterior da tíbia, pico de torque e atividade eletromiográfica do quadríceps e isquiotibiais em indivíduos com lesão do ligamento cruzado anterior em cadeia cinética aberta Analysis of anterior tibial translation, peak torque, and quadriceps and hamstrings coactivation in individuals with anterior cruciate ligament injuries performing isometric open kinetic chain exercises

    Directory of Open Access Journals (Sweden)

    Rodrigo Antunes de Vasconcelos

    2007-01-01

    Full Text Available Os objetivos deste estudo foram avaliar a translação anterior da tíbia (TAT, pico de torque isométrico e atividade eletromiográfica de indivíduos com lesão do ligamento cruzado anterior (LCA realizando contrações isométricas em cadeia cinética aberta no ângulo de 30º de flexão do joelho. Foram avaliados 20 voluntários do sexo masculino (31.1 ± 7.45 anos com ruptura completa do LCA e 20 indivíduos controle (22.2 ± 3.15 anos. Eletromiografia de superfície, artrômetro KT 1000 e um Dinamômetro isocinético foram utilizados para avaliar a atividade EMG do Quadríceps e Isquiotibiais, TAT passiva e ativa e pico de torque isométrico respectivamente durante três contrações isométricas voluntária máxima a 30 º de flexão do joelho. Os resultados demonstraram que a TAT passiva e ativa é significativamente maior em joelhos com lesão do LCA comparado ao joelho contralateral, lado dominante e não dominante do grupo controle, porém os valores da TAT ativa foram menores do que a passiva. Não houve diferenças estatisticamente significativas entre os grupos na atividade EMG do quadríceps e isquiotibiais e no pico de torque isométrico produzido durante o tarefa motora requisitada. Os resultados deste estudo demonstram que indivíduos com lesão do LCA e indivíduos controle se comportam de maneira similar em relação a pico de torque isométrico e controle motor embora a artrocinemática da articulação tibiofemural mostrou-se diferente em joelhos lesados.The aim of this study was to evaluated the anterior tibial translation (ATT, isometric peak torque and EMG activity in individuals with acl rupture performing isometric contraction in open kinetic chain in angle that provoke substantial ATT. It was evaluated 20 male subjects (31.1± 7.45 years with acl total rupture and 20 control subjects (22.2 ± 3.15 years. Electromyography, arthrometric kt 1000 and isokinetic dynamometry was used to evaluate the quadriceps and

  19. Isometric contractions reduce plantar flexor moment, Achilles tendon stiffness, and neuromuscular activity but remove the subsequent effects of stretch.

    Science.gov (United States)

    Kay, Anthony D; Blazevich, Anthony J

    2009-10-01

    The effects of isometric contractions and passive stretching on muscle-tendon mechanics and muscle activity were studied in 16 healthy human volunteers. First, peak concentric and passive ankle joint moment data were recorded on an isokinetic dynamometer with electromyographic monitoring of the triceps surae; real-time motion analysis of the lower leg and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Second, the subjects performed six 8-s maximal voluntary isometric contractions (MVICs) before repeating the passive and active trials. Although there was no decrease in isometric joint moment after MVICs, peak concentric moment was significantly reduced (11.5%, P static plantar flexor stretches before being retested 2 and 30 min after stretch. The stretch protocol caused no significant change in any measure. At 30 min after stretching, significant recovery in concentric moment and muscle activity was detected at dorsiflexed joint angles, while Achilles tendon stiffness and passive joint moment remained significantly reduced. These data show that the performance of MVICs interrupts the normal stretch-induced losses in active and passive plantar flexor joint moment and neuromuscular activity, largely because concentric strength and tendon properties were already affected. Importantly, the decrease in Achilles tendon stiffness remained 30 min later, which may be an important etiological factor for muscle-tendon strain injury risk.

  20. Growth performance of pigs subjected to multiple concurrent environmental stressors.

    Science.gov (United States)

    Hyun, Y; Ellis, M; Riskowski, G; Johnson, R W

    1998-03-01

    The effects of many single stressors have been reported, but how pigs perform when subjected to more than one or two stressors at a time, as is common in commercial swine production, has not. To study this, 256 Yorkshire x Hampshire or purebred Duroc pigs (34.7+/-.5 kg) were subjected to one of the eight treatment combinations (2 x 2 x 2 factorial) of ambient temperature (constant thermoneutral [24 degrees C] or high cycling temperature [28 to 34 degrees C]), stocking density (.56 or .25 m2/pig), and social group (static group or regrouped at the start of wk 1 and 3) during a 4-wk experiment. The temperature regimens were imposed in two adjacent mechanically ventilated rooms, and each temperature was imposed in each room across two trials. Four barrows and four gilts were assigned to each of the eight pens in the two rooms, and they always had free access to water and a corn-soybean meal-based diet. Treatments were imposed after a 7-d acclimation period at 24 degrees C and .56 m2/pig. Weight gain and feed intake were measured weekly. The main effects of each of the stressors for 4-wk ADG and ADFI were significant (P stressor interactions for ADG, ADFI, and gain:feed (G:F), there were no significant three-way interactions and only six two-way interactions, suggesting that the effects of the individual stressors were additive. Accordingly, the growth rate of pigs subjected to the single stressor of high cycling temperature, restricted space allowance, or regrouping was depressed 10, 16, and 11%, respectively, and ADG of pigs subjected to all three stressors simultaneously was depressed by 31%. Stressor additivity was further corroborated by examining the effect of stressor order, or the number of stressors imposed simultaneously. As the number of stressors increased from 0 to 3, ADG, ADFI, and G:F decreased linearly. These data suggest that multiple concurrent stressors affect growth performance of pigs in a predictable fashion (i.e., additively) and indicate that

  1. Effect of muscle mass and intensity of isometric contraction on heart rate.

    Science.gov (United States)

    Gálvez, J M; Alonso, J P; Sangrador, L A; Navarro, G

    2000-02-01

    The purpose of this study was to determine the effect of muscle mass and the level of force on the contraction-induced rise in heart rate. We conducted an experimental study in a sample of 28 healthy men between 20 and 30 yr of age (power: 95%, alpha: 5%). Smokers, obese subjects, and those who performed regular physical activity over a certain amount of energetic expenditure were excluded from the study. The participants exerted two types of isometric contractions: handgrip and turning a 40-cm-diameter wheel. Both were sustained to exhaustion at 20 and 50% of maximal force. Twenty-five subjects finished the experiment. Heart rate increased a mean of 15.1 beats/min [95% confidence interval (CI): 5.5-24.6] from 20 to 50% handgrip contractions, and 20.7 beats/min (95% CI: 11.9-29.5) from 20 to 50% wheel-turn contractions. Heart rate also increased a mean of 13.3 beats/min (95% CI: 10.4-16.1) from handgrip to wheel-turn contractions at 20% maximal force, and 18.9 beats/min (95% CI: 9. 8-28.0) from handgrip to wheel-turn contractions at 50% maximal force. We conclude that the magnitude of the heart rate increase during isometric exercise is related to the intensity of the contraction and the mass of the contracted muscle.

  2. The Advantages of Normalizing Electromyography to Ballistic Rather than Isometric or Isokinetic Tasks.

    Science.gov (United States)

    Suydam, Stephen M; Manal, Kurt; Buchanan, Thomas S

    2017-07-01

    Isometric tasks have been a standard for electromyography (EMG) normalization stemming from anatomic and physiologic stability observed during contraction. Ballistic dynamic tasks have the benefit of eliciting maximum EMG signals for normalization, despite having the potential for greater signal variability. It is the purpose of this study to compare maximum voluntary isometric contraction (MVIC) to nonisometric tasks with increasing degrees of extrinsic variability, ie, joint range of motion, velocity, rate of contraction, etc., to determine if the ballistic tasks, which elicit larger peak EMG signals, are more reliable than the constrained MVIC. Fifteen subjects performed MVIC, isokinetic, maximum countermovement jump, and sprint tasks while EMG was collected from 9 muscles in the quadriceps, hamstrings, and lower leg. The results revealed the unconstrained ballistic tasks were more reliable compared to the constrained MVIC and isokinetic tasks for all triceps surae muscles. The EMG from sprinting was more reliable than the constrained cases for both the hamstrings and vasti. The most reliable EMG signals occurred when the body was permitted its natural, unconstrained motion. These results suggest that EMG is best normalized using ballistic tasks to provide the greatest within-subject reliability, which beneficially yield maximum EMG values.

  3. Effects of fatiguing constant versus alternating intensity intermittent isometric muscle actions on maximal torque and neuromuscular responses.

    Science.gov (United States)

    Smith, C M; Housh, T J; Hill, E C; Cochrane, K C; Jenkins, N Dm; Schmidt, R J; Johnson, G O

    2016-12-14

    To determine the effects of constant versus alternating applications of torque during fatiguing, intermittent isometric muscle actions of the leg extensors on maximal voluntary isometric contraction (MVIC) torque and neuromuscular responses. Sixteen subjects performed two protocols, each consisting of 50 intermittent isometric muscle actions of the leg extensors with equal average load at a constant 60% MVIC or alternating 40 then 80% (40/80%) MVIC with a work-to-rest ratio of 6-s on and 2-s off. MVIC torque as well as electromyographic signals from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) and mechanomyographic signals from the VL were recorded pretest, immediately posttest, and 5-min posttest. The results indicated that there were no time-related differences between the 60% MVIC and 40/80% MVIC protocols. The MVIC torque decreased posttest (22 to 26%) and remained depressed 5-min posttest (9%). There were decreases in electromyographic frequency (14 to 19%) and mechanomyographic frequency (23 to 24%) posttest that returned to pretest levels 5-min posttest. There were no changes in electromyographic amplitude and mechanomyogrpahic amplitude. These findings suggested that these neuromuscular parameters did not track the fatigue-induced changes in MVIC torque after 5-min of recovery.

  4. Test-retest reliability of muscle fiber conduction velocity and fractal dimension of surface EMG during isometric contractions.

    Science.gov (United States)

    Beretta-Piccoli, Matteo; D'Antona, Giuseppe; Zampella, Cristian; Barbero, Marco; Clijsen, Ron; Cescon, Corrado

    2017-04-01

    The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1 week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays. Initial values and slope of CV and FD were used for the reliability analysis. The intraclass correlation coefficient (ICC) values for the isometric contraction at 20% MVC were (-0.09) and 0.67 for CV and FD respectively; whereas the ICC values at 60% MVC were 0.78 and 0.82 for CV and FD respectively. The Bland Altman plots for the two isometric contractions showed a mean difference close to zero, with no evident outliers between the repeated measurements: at 20% MVC 0.001 53 for FD and  -0.0277 for CV, and at 60% MVC 0.006 66 for FD and 0.009 07 for CV. Overall, our findings suggest that during isometric fatiguing contractions, CV and FD slopes are reliable variables, with potential application in clinical populations.

  5. Working memory performance and thalamus microstructure in healthy subjects.

    Science.gov (United States)

    Piras, F; Caltagirone, C; Spalletta, G

    2010-12-01

    Research on the neural basis of working memory (WM) has generally focused on cortical regions, specifically frontal and parietal areas. Comparatively, evidence of a possible involvement of deep gray matter structures, that are parts of cortico-cortical circuits linking anterior and posterior cortical areas, is far less clear. The goal of the present study is to test the hypothesis that individual structural variations within deep gray matter structures may affect the cortical networks involved in WM. To this aim, a large sample (n=181) of healthy subjects underwent a high-resolution structural magnetic resonance imaging (MRI) and a diffusion tensor imaging (DTI) scan protocol. Data of micro- (mean diffusivity, MD) and macro- (volume) structural variations of six bilateral deep gray matter structures (thalamus, caudate nucleus, putamen, hippocampus, amygdala and pallidum) and lateral ventriculi volume were analyzed in association with score in a WM (the so-called n-back task) and other neuropsychological tasks. Results showed that increased MD of bilateral thalami was the only structural parameter that significantly correlated with reduced WM performance. In particular, a voxel-by-voxel analysis revealed that the greater percentage of voxels showing significant anticorrelation between WM score and MD values were localized in those thalamic nuclei projecting to prefrontal and posterior parietal cortices. Results highlight the specific involvement of thalamus microstructure, not volume, in modulating WM performance, possibly by regulating the connections among cortical areas that are recruited during WM tasks. Copyright © 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  6. Viscoelastic performance of dielectric elastomer subject to different voltage stimulation

    Science.gov (United States)

    Sheng, Junjie; Zhang, Yuqing; Liu, Lei; Li, Bo; Chen, Hualing

    2017-04-01

    Dielectric elastomer (DE) is capable of giant deformation subject to an electric field, and demonstrates significant advantages in the potentially application of soft machines with muscle-like characteristics. Due to an inherent property of all macromolecular materials, DE exhibits strong viscoelastic properties. Viscoelasticity could cause a time-dependent deformation and lower the response speed and energy conversion efficiency of DE based actuators, thus strongly affect its electromechanical performance and applications. Combining with the rheological model of viscoelastic relaxation, the viscoelastic performance of a VHB membrane in a circular actuator configuration undergoing separately constant, ramp and sinusoidal voltages are analyzed both theoretically and experimentally. The theoretical results indicated that DE could attain a big deformation under a small constant voltage with a longer time or under a big voltage with a shorter time. The model also showed that a higher critical stretch could be achieved by applying ramping voltage with a lower rate and the stretch magnitude under sinusoidal voltage is much larger at a relatively low frequency. Finally, experiments were designed to validate the simulation and show well consistent with the simulation results.

  7. Neural adaptations in isometric contractions with EMG and force biofeedback

    OpenAIRE

    Francisco Locks; Heleodório Honorato dos Santos; Luis Carlos Carvalho; Lígia Raquel Ortiz Gomes Stolt; José Jamacy de Almeida Ferreira

    2015-01-01

    This study aimed to evaluate the quadriceps femoris neural adaptations during isometric contractions using force and electromyogram (EMG) signals as visual biofeedback. Forty-two participants were randomly assigned to three groups: EMG group, tested with EMG biofeedback; Force group, tested with force biofeedback; and Control group, tested without biofeedback. Evaluations were performed pre (baseline) and post-tests to determine the maximum force and EMG amplitude during maximal voluntary iso...

  8. Effects of Jaw Clenching and Jaw Alignment Mouthpiece Use on Force Production During Vertical Jump and Isometric Clean Pull.

    Science.gov (United States)

    Allen, Charles R; Fu, Yang-Chieh; Cazas-Moreno, Vanessa; Valliant, Melinda W; Gdovin, Jacob R; Williams, Charles C; Garner, John C

    2018-01-01

    Allen, CR, Fu, Y-C, Cazas-Moreno, V, Valliant, MW, Gdovin, JR, Williams, CC, and Garner, JC. Effects of jaw clenching and jaw alignment mouthpiece use on force production during vertical jump and isometric clean pull. J Strength Cond Res 32(1): 237-243, 2018-This study examined the effects of jaw clenching, a self-adapted, jaw-repositioning mouthpiece on force production during maximum countermovement vertical jump and maximum isometric midthigh clean pull assessments in an attempt to determine any ergogenic effect attributable to clenching, jaw-repositioning mouthpiece use, or the combination of both. Thirty-six male subjects performed vertical jump and isometric clean pull assessments from a force platform under various mouthpiece and clench conditions. A 3 × 2 (mouthpiece × clench) repeated-measures analysis of variance was conducted to analyze each of the following force production variables for both assessments: peak force, normalized peak force, and rate of force development. In addition, jump height was analyzed for the vertical jump. Results revealed improvements in peak force (F1,35 = 15.84, p ≤ 0.001, (Equation is included in full-text article.)= 0.31), normalized peak force (F1,35 = 16.28, p ≤ 0.001, (Equation is included in full-text article.)= 0.32), and rate of force development (F1,35 = 12.89, p = 0.001, (Equation is included in full-text article.)= 0.27) during the isometric clean pull assessment when participants maximally clenched their jaw, regardless of mouthpiece condition. There were no statistically significant differences in jump height, peak force, normalized peak force, or rate of force development during the vertical jump for any treatment condition. This study supports previous research demonstrating that the implementation of remote voluntary contractions such as jaw clenching can lead to concurrent activation potentiation and a resulting ergogenic effect during activities involving and requiring high-force production.

  9. Neural adaptations in isometric contractions with EMG and force biofeedback

    Directory of Open Access Journals (Sweden)

    Francisco Locks

    2015-03-01

    Full Text Available This study aimed to evaluate the quadriceps femoris neural adaptations during isometric contractions using force and electromyogram (EMG signals as visual biofeedback. Forty-two participants were randomly assigned to three groups: EMG group, tested with EMG biofeedback; Force group, tested with force biofeedback; and Control group, tested without biofeedback. Evaluations were performed pre (baseline and post-tests to determine the maximum force and EMG amplitude during maximal voluntary isometric contraction (MVIC. The tests consisted of series of MVICs in which the participants were encouraged to surpass the force or EMG thresholds determined at baseline. The vastus lateralis EMG amplitude and knee extensor force increased significantly in all groups when compared the baseline and post-test evaluations values (p < .05. EMG percentage gain was significantly different between Force and Control groups (p < .01, while force percentage gain was not different between groups. Force biofeedback was more effective in producing neural adaptations.

  10. Double-leg isometric exercise training in older men

    Directory of Open Access Journals (Sweden)

    Baross AW

    2013-01-01

    Full Text Available Anthony W Baross,1 Jonathan D Wiles,2 Ian L Swaine21Sport and Exercise Science, University of Northampton, Northampton, UK; 2Sport and Exercise Science, Canterbury Christ Church University, Canterbury, Kent, UKAbstract: Double-leg isometric training has been demonstrated to reduce resting blood pressure in young men when using electromyographic activity (EMG to regulate exercise intensity. This study assessed this training method in healthy older (45–60 years. men. Initially, 35 older men performed an incremental isometric exercise test to determine the linearity of the heart rate versus percentage peak EMG (%EMGpeak and systolic blood pressure versus %EMGpeak relationship. Thereafter, 20 participants were allocated to a training or control group. The training group performed three double-leg isometric sessions per week for 8 weeks, at 85% of peak heart rate. The training resulted in a significant reduction in resting systolic (11 ± 8 mmHg, P < 0.05 and mean arterial (5 ± 7 mmHg, P < 0.05 blood pressure. There was no significant change in resting systolic blood pressure for the control group or diastolic blood pressure in either group (all P > 0.05. These findings show that this training method, used previously in young men, is also effective in reducing resting systolic and mean arterial blood pressure in older men.Keywords: electromyography, resting blood pressure, heart rate

  11. Image Based Calculation of Perfusion and Oxyhemoglobin Saturation in Skeletal Muscle during Submaximal Isometric Contractions

    Science.gov (United States)

    Elder, Christopher P.; Cook, Ryan N.; Chance, Marti A.; Copenhaver, Elizabeth A.; Damon, Bruce M.

    2015-01-01

    The relative oxygen saturation of hemoglobin (%HbO2) and the rate of perfusion (θ̇) are important physiological quantities, particularly in organs such as skeletal muscle in which oxygen delivery and use are tightly coupled. The purpose of this study was to demonstrate the image-based calculation of %HbO2 and quantification of perfusion in skeletal muscle during isometric contractions. This was accomplished by establishing an empirical relationship between the rate of RF-reversible dephasing (R2′) and near infrared spectroscopy (NIRS)-observed oxyhemoglobin saturation (%HbO2) under conditions of arterial occlusion and constant blood volume. A calibration curve was generated and used to calculate %HbO2 from R2′ changes measured during contraction. Twelve young healthy subjects underwent 300 seconds of arterial occlusion and performed isometric contractions of the dorsiflexors at 30% of maximal contraction for 120s. Muscle perfusion was quantified during contraction by arterial spin labeling and measures of muscle T1. Comparisons between the %HbO2 values predicted from R2′ and that measured by NIRS revealed no differences between methods (p = 0.760). Muscle perfusion reached a value of 34.7 mL 100g−1 min−1 during contraction. These measurements hold future promise in measuring muscle oxygen consumption in healthy and diseased skeletal muscle. PMID:20806379

  12. Image-based calculation of perfusion and oxyhemoglobin saturation in skeletal muscle during submaximal isometric contractions.

    Science.gov (United States)

    Elder, Christopher P; Cook, Ryan N; Chance, Marti A; Copenhaver, Elizabeth A; Damon, Bruce M

    2010-09-01

    The relative oxygen saturation of hemoglobin and the rate of perfusion are important physiological quantities, particularly in organs such as skeletal muscle, in which oxygen delivery and use are tightly coupled. The purpose of this study was to demonstrate the image-based calculation of the relative oxygen saturation of hemoglobin and quantification of perfusion in skeletal muscle during isometric contractions. This was accomplished by establishing an empirical relationship between the rate of radiofrequency-reversible dephasing and near-infrared spectroscopy-observed oxyhemoglobin saturation (relative oxygen saturation of hemoglobin) under conditions of arterial occlusion and constant blood volume. A calibration curve was generated and used to calculate the relative oxygen saturation of hemoglobin from radiofrequency-reversible dephasing changes measured during contraction. Twelve young healthy subjects underwent 300 s of arterial occlusion and performed isometric contractions of the dorsiflexors at 30% of maximal contraction for 120 s. Muscle perfusion was quantified during contraction by arterial spin labeling and measures of muscle T(1). Comparisons between the relative oxygen saturation of hemoglobin values predicted from radiofrequency-reversible dephasing and that measured by near-infrared spectroscopy revealed no differences between methods (P = 0.760). Muscle perfusion reached a value of 34.7 mL 100 g(-1) min(-1) during contraction. These measurements hold future promise in measuring muscle oxygen consumption in healthy and diseased skeletal muscle. 2010 Wiley-Liss, Inc.

  13. Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans.

    Science.gov (United States)

    Kamiya, Atsunori; Michikami, Daisaku; Shiozawa, Tomoki; Iwase, Satoshi; Hayano, Junichiro; Kawada, Toru; Sunagawa, Kenji; Mano, Tadaaki

    2004-05-01

    Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P antigravity leg muscles.

  14. Hand-grip isometric strength in judo

    Directory of Open Access Journals (Sweden)

    Juan G Bonitch-Góngora

    2014-02-01

    Full Text Available The grip is an important technical and tactical aspect through which the judokas dominate the adversary, hindering the application of appropriate techniques and favoring their own attack. The judokas must have high levels of isometric force and endurance to this type of force on the gripping muscles of the forearms, as one of the key aspects for success. This article reviews the grip muscular strength and endurance profiles of judokas of different groups (gender, age and competitive level. In general, the peak isometric strength of elite judokas has not changed in the last 40 years and is similar to that reached by non-elite judokas or even registered in large populations. This indicate that the evaluation of the isometric hand grip endurance may be a more relevant parameter than the peak isometric force in judokas, as during the bouts the grip must be maintained for relatively long periods of time and the maximum force cannot be maintained for long. However there are few studies on the ability to resist successive isometric handgrip stress in judokas.

  15. Inter-rectus distance in postpartum women can be reduced by isometric contraction of the abdominal muscles: a preliminary case-control study.

    Science.gov (United States)

    Pascoal, A G; Dionisio, S; Cordeiro, F; Mota, P

    2014-12-01

    To determine the effect of isometric contraction of the abdominal muscles on inter-rectus distance in postpartum women. Preliminary case-control study. Research laboratory. Ten postpartum women {mean age 30 [standard deviation (SD) 4] years; mean weight 58 (SD 7) kg; mean height 159 (SD 4) cm} and 10 nulliparous (control) women [mean age 28 (SD 2) years; mean weight 56 (SD 6) kg; mean height 160 (SD 6) cm]. Ultrasound images from the anterior abdominal wall were recorded at rest (supine position) and during an abdominal isometric contraction, with the subject actively performing an abdominal crunch (crook lying position). Two-way analysis of variance was used to compare the inter-rectus distance between groups (postpartum vs control) and between levels of abdominal muscle activation (rest vs isometric contraction). Inter-rectus distance 2cm above the level of the umbilicus. The inter-rectus distance was significantly greater in the postpartum group compared with the control group [14.7 (SD 3.1) mm vs 9.6 (SD 2.8) mm; mean difference 5.1mm; 95% confidence interval (CI) 3.4 to 6.8]. The inter-rectus distance was significantly lower during isometric contraction compared with rest [10.7 (SD 3.1) mm vs 13.4 (SD 3.1) mm; mean difference 2.8mm; 95% CI 1.2 to 4.5]. No interaction was found between group and muscle contraction. The inter-rectus distance was significantly higher in postpartum women compared with controls, and significantly lower during isometric contraction of the abdominal muscles (abdominal crunch) compared with rest. Copyright © 2014 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  16. EMG analysis of shoulder muscle fatigue during resisted isometric shoulder elevation.

    Science.gov (United States)

    Minning, Stephen; Eliot, Colin A; Uhl, Tim L; Malone, Terry R

    2007-04-01

    The purpose of this study was to determine if a difference existed in the rate of fatigue of select shoulder muscles during isometric shoulder elevation and if the measured rate of fatigue was consistent from day to day. Shoulder muscle fatigue has been associated with alterations in joint mechanics and possibly contributes to shoulder dysfunction. While research exists, there is limited information on an objective and reliable measure of shoulder fatigue. Sixteen asymptomatic subjects were evaluated. The subjects held a weight equivalent to 60% of his/her Maximum Voluntary Isometric Contraction (MVIC) while elevating in the scapular plane. Surface electrodes were applied to collect electromyographic activity from the upper trapezius, middle deltoid, serratus anterior, and lower trapezius muscles while the arm was held at 90 degrees elevation. Data collection ceased when the subject was no longer able to maintain 90 degrees of elevation. The subject then rested and a second trial performed. One week later, the two-trial procedure was repeated. A significant interaction of trial x day x muscle was found for the rate of fatigue. Post hoc analysis revealed that the rate of fatigue of the middle deltoid was significantly greater than the other muscles tested. The intraday reliability was good for all muscles but interday reliability was poor except for the middle deltoid. This study suggests that the middle deltoid appears to fatigue faster than the other shoulder muscles tested at the selected level of shoulder elevation. This should be considered in designing a rehabilitation program to develop a sequence that does not overly fatigue the middle deltoid.

  17. Acute effects of kinesio taping on knee extensor peak torque and electromyographic activity after exhaustive isometric knee extension in healthy young adults.

    Science.gov (United States)

    Yeung, Simon S; Yeung, Ella W; Sakunkaruna, Yosawin; Mingsoongnern, Sutida; Hung, Wing Y; Fan, Yun L; Iao, Heng C

    2015-05-01

    To evaluate the effect of Kinesio Tex tape and its method of application, Kinesio Taping (KT) on knee extensor performance before and after an exhaustive isometric knee extension exercise. Single-blinded, randomized control trial. Centre for Sports Training and Rehabilitation at The Hong Kong Polytechnic University. Twenty-six healthy volunteers with no history of knee injuries. Subjects were randomized to either the KT or sham taping group. The effects of KT on the neuromuscular performance of the knee extensors were measured before and after KT application, and immediately and 5 and 10 minutes after an exhaustive isometric knee extension exercise. Within-group analyses revealed a significant effect of time on the peak torque in isometric knee extension (F2.73,65.44 = 24.5, P Kinesio taping is commonly seen in the sports arena. The popularity is presumably due to the general belief in its injury prevention and enhancement of muscle performance. The results of the present findings suggested that KT shortens the time to reach peak torque generation. Aside from this, there is no other significant positive effect on muscle performance. Further investigation on the effects of KT on muscle performance is warranted.

  18. Performance of FRCM strengthened beams subject to fatigue.

    Science.gov (United States)

    2017-05-31

    Fabric Reinforced Cementitious Matrix (FRCM) systems have been developed to strengthen or rehabilitate existing concrete and masonry structures subject to damage, steel reinforcement corrosion or requiring resistance capacity improvements due to incr...

  19. The impact of subjectivity in performance evaluation practices on public sector managers' motivation

    NARCIS (Netherlands)

    van Rinsum, M.; Verbeeten, F.H.M.

    2012-01-01

    We conduct an explorative study to investigate the effect of subjectivity in performance evaluation practices on managerial motivation in public sector organisations. Increased subjectivity can enhance motivation if supervisors are able to provide better informational feedback. However, subjectivity

  20. Sex differences in variances of multi-channel surface electromyography distribution of the vastus lateralis muscle during isometric knee extension in young adults.

    Science.gov (United States)

    Nishikawa, Yuichi; Watanabe, Kohei; Takahashi, Tetsuya; Hosomi, Naohisa; Orita, Naoya; Mikami, Yukio; Maruyama, Hirofumi; Kimura, Hiroaki; Matsumoto, Masayasu

    2017-03-01

    The aim of the present study was to compare spatial electromyographic potential distribution during force production between healthy young female and male using multi-channel surface electromyography (multi-SEMG). Thirty healthy subjects (15 females) performed sustained isometric knee extension at 10% maximal voluntary contraction (MVC) task for 120 s. Multi-SEMG signals from the vastus lateralis muscle were detected and the modified entropy, coefficient of variation (CV), and correlation coefficient determined. The modified entropy and CV showed significant interaction and difference between females and males at all time points during the 10% MVC task. The correlation coefficient in females was significantly lower at 90 and 120 s than that of males. The multi-SEMG potential distribution pattern in females showed more varied motor unit recruitment during sustained low-intensity isometric contraction than that of males. Variations in motor unit recruitment may result from recruitment and/or de-recruitment of motor units.

  1. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    OpenAIRE

    Annemarie eBoschloo; Lydia eKrabbendam; Sanne eDekker; Lee, Nikki C.; Renate ede Groot; Jelle eJolles

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness – ‘I feel sleepy during the first hours at school’ – appeared to predict both school grades and self-repor...

  2. The effects of 16 months of angle-specific isometric strengthening exercises in midrange on torque of the knee extensor muscles in osteoarthritis of the knee: a case study.

    Science.gov (United States)

    Marks, R

    1994-08-01

    Although often advocated for arthritis rehabilitation, several studies conducted on healthy subjects have demonstrated conflicting results as to whether isometric strengthening exercises performed at one joint angle can result in strength gains at other angles. The objective of this study was to determine whether midrange strength training of the quadriceps surrounding an osteoarthritic knee would increase strength in this part of the range of motion as well at other knee angles. The midrange position was chosen because the subject, a 57-year-old female with a 2-year history of moderately severe osteoarthritis of the left knee, had greatest weakness in this position. The training occurred three times per week for 16 months using a resistance training program of three sets of two maximal isometric contractions at a knee angle of 60 degrees. The dependent variable of maximal isometric knee extensor torque was recorded on an isokinetic dynamometer at knee angles of 90, 60, and 30 degrees at 6 weeks, 1 year, and 16 months. These data demonstrated a progressive torque increase at all angles over the 16-month period, with a steeper slope at the training angle. Contrary to the specificity of training concept, angle-specific strengthening in midrange may be sufficient to strengthen the extensors surrounding an osteoarthritic knee through a wide range of motion. Mid-range isometric strengthening exercises might thus prove useful in the rehabilitation of patients with knee osteoarthritis who are unable to exercise their weakened quadriceps at other angles due to pain or swelling.

  3. Isometric hip muscle strength in posttraumatic below-knee amputees

    Directory of Open Access Journals (Sweden)

    Jandrić Slavica

    2007-01-01

    Full Text Available Background/Aim. Traumas and war injuries, next to chronic occlusive artery disease and diabetes mellitus-derived complications, are the most frequent cause of the lower limbs amputation. They affect mostly younger population that need a higher level of activities as compared with the elderly. Medical rehabilitation is very significant for the muscle performance improvement in this population providing their social reintegration. The aim of this study was to investigate the effect of below-knee amputation on the hip isometric muscle strength and effect of rehabilitation on improvement of hip muscle strength in below-knee amputees, secondary to war wounding. Methods. Forty below-knee amputees (after war wounding, average age 35.6±10.6 years, that were included in primary rehabilitation program with prosthetics, were examined. Objective parameters were used to evaluate therapeutical effects. Isometric muscle strength of hip flexors, extensors, abductors and adductors was measured by dynamometer and expressed in Newton (N at admission, control and discharge for each patient. Average length of the treatment was 51 ± 34.1 days. Results. For isometric hip flexors (t = - 1.99346, p < 0.05, extensors (t = -4.629073, p < 0.001, abductors (t = -4.9408, p < 0.001 and adductors (t = -2.00228, p < 0.05, muscle strength was significantly less on the amputated than on nonamputated side. The highest differences in muscle strength between amputated and nonamputated limbs were noted for hip abductors (26.6% and extensors (23.3%. There was significant improvement of mean values of strength for all examined hip muscles after rehabilitation and prosthetics for both legs in comparison to beginning of the therapy. The hip abductor on the amputated side was for 19.4% weaker after rehabilitation in comparison to the nonamputated limb. Conclusion. Decreases of isometric muscle strength in all examined hip muscles were observed, more in the amputated limb. Rehabilitation

  4. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    NARCIS (Netherlands)

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; De Groot, Renate; Jolles, Jelle

    2016-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11–18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school

  5. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    NARCIS (Netherlands)

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; De Groot, Renate; Jolles, Jelle

    2018-01-01

    This study investigated the relation between sleep and school performance in a large sam- ple of 561 adolescents aged 11–18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school

  6. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    NARCIS (Netherlands)

    Boschloo, A.; Krabbendam, L.; Dekker, S.; Lee, N.; Groot, R. de; Jolles, J.

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school

  7. Comparison of blood pressure and heart rate responses to isometric exercise and passive muscle stretch in humans.

    Science.gov (United States)

    Baum, K; Selle, K; Leyk, D; Essfeld, D

    1995-01-01

    The responses of mean arterial blood pressure (BPa) and heart rate (fc) to isometric contraction and passive stretch were compared in seven healthy male subjects at identical external forces. They were investigated in the sitting position with the hip and knee joint flexed to 90 degrees. Each subject performed two tests, separated by a day, in which the stimuli were applied in random order. After 5 min of rest they performed either 10-min static plantar flexion of one calf (200 N) or 10 min of passive calf muscle stretch at the same load. After 5-min rest, the second stimulus was applied for a further 10 min followed by 5-min rest. The second test was identical except for the sequence of the stimuli. The BPa was measured by a noninvasive and continuous method. Contraction of the vastus lateralis, gastrocnemius lateralis, and soleus muscles were determined by the myo-electric activity (electromyogram, EMG) by means of surface electrodes. The EMG activity of the vastus lateralis muscle remained at resting values throughout the experiments. Increases in EMG activity could only be detected for the triceps surae muscles during isometric contraction. During the initial 2 min of stimulation the BPa and fc responses to active contraction and passive stretch were comparable. Thereafter, both parameters showed significantly higher values during contraction. It was concluded that mechanical stress may have contributed to the early response of BPa during both passive stretch and voluntary contraction but that chemical stimuli were needed to maintain the peripheral cardiovascular drive.

  8. Comparative study of maximum isometric grip strength in different sports

    Directory of Open Access Journals (Sweden)

    Noé Gomes Borges Junior

    2009-06-01

    Full Text Available The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

  9. Changes in the tibialis anterior tendon moment arm from rest to maximum isometric dorsiflexion: in vivo observations in man.

    Science.gov (United States)

    Maganaris, C N; Baltzopoulos, V; Sargeant, A J

    1999-11-01

    In the present study, we examined the hypothesis that the tibialis anterior tendon moment arm increases during maximum isometric dorsiflexion as compared with rest. In musculoskeletal modelling applications, moment arms from passive muscles at rest are assumed representative of those measured during isometric muscle contraction. The validity of this assumption is questionable in musculotendon actuators enclosed by retinacular systems as in tibialis anterior. Sagittal-plane magnetic resonance images of the right ankle were taken in six subjects at rest and during maximum isometric dorsiflexion at six ankle angles between dorsiflexion and plantarflexion having the body placed in the supine position and the knee flexed at 90 degrees. Instant centres of rotation in the tibio-talar joint, tibialis anterior tendon action lines and moment arms were identified in the sagittal plane at ankle angles of -15 degrees, 0 degrees,+15 degrees and +30 degrees at rest and during maximum isometric dorsiflexion. At any given ankle angle, the tibialis anterior tendon moment arm during maximum isometric dorsiflexion increased by 0.9-1.5 cm (Pdorsiflexion is invalid. Erroneous tendon forces, muscle stresses and joint moments by as much as 30% would be calculated using resting tibialis anterior tendon moment arms in the moment equilibrium equation around the ankle joint during maximum isometric dorsiflexion. A substantial increase in the tibialis anterior tendon moment arm occurs from rest to maximum isometric dorsiflexion. This needs to be taken into consideration when using planimetric musculoskeletal modelling for analysing maximal static ankle dorsiflexion loads.

  10. Performativity / Expressivity: The Mobile Micro Screen and Its Subject.

    NARCIS (Netherlands)

    Verhoeff, N.|info:eu-repo/dai/nl/241603471

    2014-01-01

    Informed by a tradition of cinema and visual culture studies on the one hand, and science and technology studies and new materialism on the other, we mobilize Peircean semiotics in order to theorize new media technologies and related practices. Our question is, in what way performativity and

  11. Subjective Sleepiness and Sleep Quality in Adolescents are Related to Objective and Subjective Measures of School Performance

    OpenAIRE

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; De Groot, Renate; Jolles, Jelle

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11–18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness – “I feel sleepy during the first hours at school” – appeared to predict both school grades and self-repo...

  12. Interactions of task and subject variables among continuous performance tests.

    Science.gov (United States)

    Denney, Colin B; Rapport, Mark D; Chung, Kyong-Mee

    2005-04-01

    Contemporary models of working memory suggest that target paradigm (TP) and target density (TD) should interact as influences on error rates derived from continuous performance tests (CPTs). The present study evaluated this hypothesis empirically in a typically developing, ethnically diverse sample of children. The extent to which scores based on different combinations of these task parameters showed different patterns of relationship to age, intelligence, and gender was also assessed. Four continuous performance tests were derived by combining two target paradigms (AX and repeated letter target stimuli) with two levels of target density (8.3% and 33%). Variations in mean omission (OE) and commission (CE) error rates were examined within and across combinations of TP and TD. In addition, a nested series of structural equation models was utilized to examine patterns of relationship among error rates, age, intelligence, and gender. Target paradigm and target density interacted as influences on error rates. Increasing density resulted in higher OE and CE rates for the AX paradigm. In contrast, the high density condition yielded a decline in OE rates accompanied by a small increase in CEs using the repeated letter CPT. Target paradigms were also distinguishable on the basis of age when using OEs as the performance measure, whereas combinations of age and intelligence distinguished between density levels but not target paradigms using CEs as the dependent measure. Different combinations of target paradigm and target density appear to yield scores that are conceptually and psychometrically distinguishable. Consequently, developmentally appropriate interpretation of error rates across tasks may require (a) careful analysis of working memory and attentional resources required for successful performance, and (b) normative data bases that are differently stratified with respect to combinations of age and intelligence.

  13. Contribution of the cerebellum to the coupling of grip force and pull force during an isometric precision grip task.

    Science.gov (United States)

    Meindl, Tobias; Schmid, Barbara C; Timmann, Dagmar; Kolb, Florian P; Kutz, Dieter F

    2012-03-01

    This study addresses the influence of the cerebellum on the performance of an isometric precision grip task. For the task, in which the process of "picking a raspberry" is simulated, grip force and pull force had to be increased linearly for a duration of 1-5 s (pull phase) to accomplish the task skillfully. The performance of 11 patients suffering from degenerative cerebellar disease was analyzed and compared with the performance of 11 age- and sex-matched healthy control subjects. Patients with cerebellar disease showed systematic deviations of the pull force slope from a linear trend, dividing the pull phase into two intervals. After an initial sharp and brief increase of pull force (first interval), patients maintained the achieved pull force level almost constant without further increase (second interval). Although controls showed changes in the pull force slope also, they increased pull force during the whole pull phase. Coupling of grip force and pull force was analyzed using stochastic frontier analysis. This technique allows covariation of grip force and the resulting pull force to be analyzed depending on the variation of the grip force. In the patients, grip force and pull force were coupled efficiently only in the first interval. During the second interval, grip force was often exaggerated compared with pull force. In conclusion, patients with cerebellar diseases have difficulties in producing smooth isometric movements and in coupling grip force and pull force efficiently.

  14. Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power

    Science.gov (United States)

    Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.

    2009-01-01

    Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of

  15. Neuromuscular fatigue following isometric contractions with similar torque time integral.

    Science.gov (United States)

    Rozand, V; Cattagni, T; Theurel, J; Martin, A; Lepers, R

    2015-01-01

    Torque time integral (TTI) is the combination of intensity and duration of a contraction. The aim of this study was to compare neuromuscular alterations following different isometric sub-maximal contractions of the knee extensor muscles but with similar TTI. Sixteen participants performed 3 sustained contractions at different intensities (25%, 50%, and 75% of Maximal Voluntary Contraction (MVC) torque) with different durations (68.5±33.4 s, 35.1±16.8 s and 24.8±12.9 s, respectively) but similar TTI value. MVC torque, maximal voluntary activation level (VAL), M-wave characteristics and potentiated doublet amplitude were assessed before and immediately after the sustained contractions. EMG activity of the vastus lateralis (VL) and -rectus femoris (RF) muscles was recorded during the sustained contractions. MVC torque reduction was similar in the 3 conditions after the exercise (-23.4±2.7%). VAL decreased significantly in a similar extent (-3.1±1.3%) after the 3 sustained contractions. Potentiated doublet amplitude was similarly reduced in the 3 conditions (-19.7±1.5%), but VL and RF M-wave amplitudes remained unchanged. EMG activity of VL and RF muscles increased in the same extent during the 3 contractions (VL: 54.5±40.4%; RF: 53.1±48.7%). These results suggest that central and peripheral alterations accounting for muscle fatigue are similar following isometric contractions with similar TTI. TTI should be considered in the exploration of muscle fatigue during sustained isometric contractions. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Relationship Between the Range of Motion and Isometric Strength of Elbow and Shoulder Joints and Ball Velocity in Women Team Handball Players.

    Science.gov (United States)

    Schwesig, René; Hermassi, Souhail; Wagner, Herbert; Fischer, David; Fieseler, Georg; Molitor, Thomas; Delank, Karl-Stefan

    2016-12-01

    Schwesig, R, Hermassi, S, Wagner, H, Fischer, D, Fieseler, G, Molitor, T, and Delank, K-S. Relationship between the range of motion and isometric strength of elbow and shoulder joints and ball velocity in women team handball players. J Strength Cond Res 30(12): 3428-3435, 2016-The aims of this study were to investigate relationships between isometric strength and range of motion (ROM) of shoulder and elbow joints and compare 2 different team handball throwing techniques in women team handball. Twenty highly experienced women team handball players (age: 20.7 ± 2.9 years; body mass: 68.4 ± 6.0 kg; and height: 1.74 ± 0.06 m) participated in this study. The isometric strength (hand-held dynamometer) and ROM (goniometer) of shoulder and elbow joints were measured at the beginning of the preseasonal training. After clinical examination, the subjects performed 3 standing throws with run-up (10 m) and 3 jump throws over a hurdle (0.20 m). The mean ball velocity was calculated from 3 attempts and measured using a radar gun. The results showed that the ball velocity of the standing throw with run-up (vST) was significantly higher than that of the jump throw (vJT) (25.5 ± 1.56 vs. 23.2 ± 1.31 m·s; p handball players.

  17. Relation between Peak Power Output in Sprint Cycling and Maximum Voluntary Isometric Torque Production.

    Science.gov (United States)

    Kordi, Mehdi; Goodall, Stuart; Barratt, Paul; Rowley, Nicola; Leeder, Jonathan; Howatson, Glyn

    2017-08-01

    From a cycling paradigm, little has been done to understand the relationships between maximal isometric strength of different single joint lower body muscle groups and their relation with, and ability to predict PPO and how they compare to an isometric cycling specific task. The aim of this study was to establish relationships between maximal voluntary torque production from isometric single-joint and cycling specific tasks and assess their ability to predict PPO. Twenty male trained cyclists participated in this study. Peak torque was measured by performing maximum voluntary contractions (MVC) of knee extensors, knee flexors, dorsi flexors and hip extensors whilst instrumented cranks measured isometric peak torque from MVC when participants were in their cycling specific position (ISOCYC). A stepwise regression showed that peak torque of the knee extensors was the only significant predictor of PPO when using SJD and accounted for 47% of the variance. However, when compared to ISOCYC, the only significant predictor of PPO was ISOCYC, which accounted for 77% of the variance. This suggests that peak torque of the knee extensors was the best single-joint predictor of PPO in sprint cycling. Furthermore, a stronger prediction can be made from a task specific isometric task. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Motor Unit Activity during Fatiguing Isometric Muscle Contraction in Hemispheric Stroke Survivors

    Directory of Open Access Journals (Sweden)

    Lara McManus

    2017-11-01

    Full Text Available Enhanced muscle weakness is commonly experienced following stroke and may be accompanied by increased susceptibility to fatigue. To examine the contributions of central and peripheral factors to isometric muscle fatigue in stroke survivors, this study investigates changes in motor unit (MU mean firing rate, and action potential duration during, and directly following, a sustained submaximal fatiguing contraction at 30% maximum voluntary contraction (MVC. A series of short contractions of the first dorsal interosseous muscle were performed pre- and post-fatigue at 20% MVC, and again following a 10-min recovery period, by 12 chronic stroke survivors. Individual MU firing times were extracted using surface EMG decomposition and used to obtain the spike-triggered average MU action potential waveforms. During the sustained fatiguing contraction, the mean rate of change in firing rate across all detected MUs was greater on the affected side (-0.02 ± 0.03 Hz/s than on the less-affected side (-0.004 ± 0.003 Hz/s, p = 0.045. The change in firing rate immediately post-fatigue was also greater on the affected side than less-affected side (-13.5 ± 20 and 0.1 ± 19%, p = 0.04. Mean MU firing rates increased following the recovery period on the less-affected side when compared to the affected side (19.3 ± 17 and 0.5 ± 20%, respectively, p = 0.03. MU action potential duration increased post-fatigue on both sides (10.3 ± 1.2 to 11.2 ± 1.3 ms on the affected side and 9.9 ± 1.7 to 11.2 ± 1.9 ms on the less-affected side, p = 0.001 and p = 0.02, respectively, and changes in action potential duration tended to be smaller in subjects with greater impairment (p = 0.04. This study presents evidence of both central and peripheral fatigue at the MU level during isometric fatiguing contraction for the first time in stroke survivors. Together, these preliminary observations indicate that the response to an isometric fatiguing contraction differs between the

  19. The psychophysics of workload - A second look at the relationship between subjective measures and performance

    Science.gov (United States)

    Gopher, D.; Chillag, N.; Arzi, N.

    1985-01-01

    Load estimates based upon subjective and performance indices were compared for subjects performing size matching and letter typing tasks under 6 levels of priorities, in single and dual task conditions. Each half of the group used a different task as reference in their subjective judgement. The results are interpreted to indicate that subjective measures are especially sensitive to voluntary allocation of attention and to the load on working memory. Association with performance is expected whenever these two factors are main determinants of performance efficiency, otherwise the two are likely to dissociate.

  20. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    Directory of Open Access Journals (Sweden)

    Annemarie eBoschloo

    2013-02-01

    Full Text Available This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness – ‘I feel sleepy during the first hours at school’ – appeared to predict both school grades and self-reported school performance. Sleep quality on the other hand – as a measure of (uninterrupted sleep and/or problems falling asleep or waking up – predicted parent-reported school performance. Self- and parent-reported school performance correlated only moderately with school grades. So it turns out that the measures used to measure either sleep or school performance impacts whether or not a relation is found. Further research on sleep and school performance should take this into account. The findings do underscore the notion that sleep in adolescence can be important for learning. They are compatible with the hypothesis that a reduced sleep quality can give rise to sleepiness in the first hours at school which results in lower school performance. This notion could have applied value in counseling adolescents and their parents in changing adolescents’ sleep behavior.

  1. Subjective Sleepiness and Sleep Quality in Adolescents are Related to Objective and Subjective Measures of School Performance.

    Science.gov (United States)

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; de Groot, Renate; Jolles, Jelle

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness - "I feel sleepy during the first hours at school" - appeared to predict both school grades and self-reported school performance. Sleep quality on the other hand - as a measure of (un)interrupted sleep and/or problems falling asleep or waking up - predicted parent-reported school performance. Self- and parent-reported school performance correlated only moderately with school grades. So it turns out that the measures used to measure either sleep or school performance impacts whether or not a relation is found. Further research on sleep and school performance should take this into account. The findings do underscore the notion that sleep in adolescence can be important for learning. They are compatible with the hypothesis that a reduced sleep quality can give rise to sleepiness in the first hours at school which results in lower school performance. This notion could have applied value in counseling adolescents and their parents in changing adolescents' sleep behavior.

  2. How does functionality proceed in ACL reconstructed subjects? Proceeding of functional performance from pre- to six months post-ACL reconstruction

    Science.gov (United States)

    Stetter, Bernd Josef; Stein, Thorsten; Ellermann, Andree; Flechtenmacher, Johannes; Eberle, Christian; Sell, Stefan; Potthast, Wolfgang

    2017-01-01

    This is the first study examining functionality of subjects with anterior cruciate ligament (ACL) tears and a subsequent reconstruction comprehensively by multiple test sessions from pre- to six months post-reconstruction. The purpose was to evaluate if a generally applied rehabilitation program restores functionality to levels of healthy controls. Subjects with unilateral tears of the ACL were compared to matched healthy controls throughout the rehabilitation. 20 recreational athletes were tested: T1 (preoperative), 6 weeks after tear; T2, 6 weeks, T3, 3 months, T4, 6 months post-reconstruction. At all test sessions, subjects self-evaluated their activity level with the Tegner activity score and their knee state with the Knee Injury and Osteoarthritis Outcome Score. Passive range of motion during knee flexion and extension and leg circumference were measured as functional clinical tests. Bilateral countermovement jumps, one-leg jumps for distance and isometric force tests in knee flexion and extension with 90° and 110° knee angle were conducted as functional performance tests. For determination of functionality, leg symmetry indices (LSIs) were calculated by dividing values of the injured by the uninjured leg. In the ACL group most LSIs decreased from T1 to T2, and increased from T2 and T3 to T4. LSIs of ACL subjects remained lower than LSIs of healthy controls at 6 months post-reconstruction in nearly all parameters. Self-evaluation of ACL subjects showed, additionally, that activity level was lower than the pre-injury level at 6 months post-reconstruction. Low LSIs and low self-evaluation indicate that knee joint functionality is not completely restored at 6 months post-reconstruction. The study shows that multiple comprehensive testing throughout the rehabilitation gives detailed images of the functional state. Therefore, the functional state of ACL reconstructed individuals should be evaluated comprehensively and continuously throughout the rehabilitation to

  3. Strength, endurance, and work capacity after muscle strengthening exercise in postpolio subjects.

    Science.gov (United States)

    Agre, J C; Rodriquez, A A; Franke, T M

    1997-07-01

    To determine whether a 12-week home quadriceps muscle strengthening exercise program would increase muscle strength, isometric endurance, and tension time index (TTI) in postpolio syndrome subjects without adversely affecting the surviving motor units or the muscle. A longitudinal study to investigate the effect of a 12-week exercise program on neuromuscular function and electromyographic variables. Neuromuscular laboratory of a university hospital. Seven subjects were recruited from a cohort of 12 subjects who had participated in a previous exercise study. All subjects had greater than antigravity strength of the quadriceps. Upon completion of a postpolio questionnaire, all acknowledged common postpolio syndrome symptoms such as new fatigue, pain, and weakness; 6 of the 7 acknowledged new strength decline. On Mondays and Thursdays subjects performed three sets of four maximal isometric contractions of the quadriceps held for 5 seconds each. On Tuesdays and Fridays subjects performed three sets of 12 dynamic knee extension exercises with ankle weights. Neuromuscular variables of the quadriceps muscles were measured at the beginning and completion of the exercise program and included: isokinetic peak torque (ISOKPT, at 60 degrees/sec angular velocity) and total work performed of four contractions (ISOKTW), isometric peak torque (MVC), endurance (EDUR, time subject could hold isometric contraction at 40% of the initial MVC), isometric tension time index (TTI, product of endurance time and torque at 40% of MVC), and initial and final ankle weight (WGT, kg) lifted. Electromyographic variables included: fiber density (FD), jitter (MCD), and blocking (BLK) from single fiber assessment and median macro amplitude (MACRO). Serum creatine kinase (CK) was also measured initially and at 4-week intervals throughout the study. The following variables significantly (p .05) change: FD, MCD, BLK, MACRO, and CK. This home exercise program significantly increased strength, endurance

  4. Shear modulus estimation on vastus intermedius of elderly and young females over the entire range of isometric contraction.

    Directory of Open Access Journals (Sweden)

    Cong-Zhi Wang

    Full Text Available Elderly people often suffer from sarcopenia in their lower extremities, which gives rise to the increased susceptibility of fall. Comparing the mechanical properties of the knee extensor/flexors on elderly and young subjects is helpful in understanding the underlying mechanisms of the muscle aging process. However, although the stiffness of skeletal muscle has been proved to be positively correlated to its non-fatiguing contraction intensity by some existing methods, this conclusion has not been verified above 50% maximum voluntary contraction (MVC due to the limitation of their measurement range. In this study, a vibro-ultrasound system was set up to achieve a considerably larger measurement range on muscle stiffness estimation. Its feasibility was verified on self-made silicone phantoms by comparing with the mechanical indentation method. The system was then used to assess the stiffness of vastus intermedius (VI, one of the knee extensors, on 10 healthy elderly female subjects (56.7 ± 4.9 yr and 10 healthy young female subjects (27.6 ± 5.0 yr. The VI stiffness in its action direction was confirmed to be positively correlated to the % MVC level (R2 = 0.999 over the entire range of isometric contraction, i.e. from 0% MVC (relaxed state to 100% MVC. Furthermore, it was shown that there was no significant difference between the mean VI shear modulus of the elderly and young subjects in a relaxed state (p > 0.1. However, when performing step isometric contraction, the VI stiffness of young female subjects was found to be larger than that of elderly participants (p < 0.001, especially at the relatively higher contraction levels. The results expanded our knowledge on the mechanical property of the elderly's skeletal muscle and its relationship with intensity of active contraction. Furthermore, the vibro-ultrasound system has a potential to become a powerful tool for investigating the elderly's muscle diseases.

  5. Isometric elbow extensors strength in supine- and prone-lying positions.

    Science.gov (United States)

    Abdelzaher, Ibrahim E; Ababneh, Anas F; Alzyoud, Jehad M

    2013-01-01

    The purpose of this study was to compare isometric strength of elbow extensors measured in supine- and prone-lying positions at elbow flexion angles of 45 and 90 degrees. Twenty-two male subjects under single-blind procedures participated in the study. Each subject participated in both supine-lying and prone-lying measuring protocols. Calibrated cable tensiometer was used to measure isometric strength of the right elbow extensors and a biofeedback electromyography was used to assure no substitution movements from shoulder girdle muscles. The mean values of isometric strength of elbow extensors measured from supine-lying position at elbow flexion angles of 45 and 90 degrees were 11.1  ±  4.2 kg and 13.1  ±  4.6 kg, while those measured from prone-lying position were 9.9  ±  3.6 kg and 12  ±  4.2 kg, respectively. There is statistical significant difference between the isometric strength of elbow extensors measured from supine-lying position at elbow flexion angles of 45 and 90 degrees compared to that measured from prone-lying position (p  lying starting position is better than prone-lying starting position.

  6. Higher Neuromuscular Manifestations of Fatigue in Dynamic than Isometric Pull-Up Tasks in Rock Climbers

    Directory of Open Access Journals (Sweden)

    Boccia Gennaro

    2015-09-01

    Full Text Available Neuromuscular assessment of rock climbers has been mainly focused on forearm muscles in the literature. We aimed to extend the body of knowledge investigating on two other upper limb muscles during sport-specific activities in nine male rock climbers. We assessed neuromuscular manifestations of fatigue recording surface electromyographic signals from brachioradialis and teres major muscles, using multi-channel electrode arrays. Participants performed two tasks until volitional exhaustion: a sequence of dynamic pull-ups and an isometric contraction sustaining the body at half-way of a pull-up (with the elbows flexed at 90°. The tasks were performed in randomized order with 10 minutes of rest in between. The normalized rate of change of muscle fiber conduction velocity was calculated as the index of fatigue. The time-to-task failure was significantly shorter in the dynamic (31 ±10 s than isometric contraction (59 ±19 s. The rate of decrease of muscle fiber conduction velocity was found steeper in the dynamic than isometric task both in brachioradialis (isometric: −0.2 ±0.1%/s; dynamic: −1.2 ±0.6%/s and teres major muscles (isometric: −0.4±0.3%/s; dynamic: −1.8±0.7%/s. The main finding was that a sequence of dynamic pull-ups lead to higher fatigue than sustaining the body weight in an isometric condition at half-way of a pull-up. Furthermore, we confirmed the possibility to properly record physiological CV estimates from two muscles, which had never been studied before in rock climbing, in highly dynamic contractions.

  7. Comparative study of maximum isometric grip strength in different sports

    Directory of Open Access Journals (Sweden)

    Noé Gomes Borges Junior

    2009-01-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2009v11n3p292   The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

  8. A multilevel approach to relating subjective workload to performance after shifts in task demand.

    Science.gov (United States)

    Mracek, Derek L; Arsenault, Matthew L; Day, Eric Anthony; Hardy, Jay H; Terry, Robert A

    2014-12-01

    The aim of this laboratory experiment was to demonstrate how taking a longitudinal, multilevel approach can be used to examine the dynamic relationship between subjective workload and performance over a given period of activity involving shifts in task demand. Subjective workload and conditions of the performance environment are oftentimes examined via cross-sectional designs without distinguishing within-from between-person effects. Given the dynamic nature of performance phenomena, multilevel designs coupled with manipulations of task demand shifts are needed to better model the dynamic relationships between state and trait components of subjective workload and performance. With a sample of 75 college students and a computer game representing a complex decision-making environment, increases and decreases in task demand were counterbalanced and subjective workload and performance were measured concurrently in regular intervals within performance episodes. Data were analyzed using hierarchical linear modeling. Both between- and especially within-person effects were dynamic. Nevertheless, at both levels of analysis, higher subjective workload reflected performance problems, especially more downstream from increases in task demand. As a function of cognitive-energetic processes, shifts in task demand are associated with changes in how subjective workload is related to performance over a given period of activity. Multilevel, longitudinal approaches are useful for distinguishing and examining the dynamic relationships between state and trait components of subjective workload and performance. The findings of this research help to improve the understanding of how a sequence of demands can exceed a performer's capability to respond to further demands.

  9. Determinants of Girls' Performance in Science, Mathematics and Technology Subjects in Public Secondary Schools in Kenya

    Science.gov (United States)

    Musau, Lydia Mbaki; Migosi, Joash; Muola, James Matee

    2013-01-01

    There has been incessant low academic performance in Science, Mathematics and Technology (SMT) subjects especially among girls at form four level in Kitui Central District over the years. The aim of this study was to investigate the determinants of girls' performance in SMT subjects in public secondary schools. Using ex-post-facto survey research…

  10. Whole-body isometric force/torque measurements for functional assessment in neuro-rehabilitation: platform design, development and verification.

    Science.gov (United States)

    Mazzoleni, Stefano; Toth, Andras; Munih, Marko; Van Vaerenbergh, Jo; Cavallo, Giuseppe; Micera, Silvestro; Dario, Paolo; Guglielmelli, Eugenio

    2009-10-30

    One of the main scientific and technological challenges of rehabilitation bioengineering is the development of innovative methodologies, based on the use of appropriate technological devices, for an objective assessment of patients undergoing a rehabilitation treatment. Such tools should be as fast and cheap to use as clinical scales, which are currently the daily instruments most widely used in the routine clinical practice. A human-centered approach was used in the design and development of a mechanical structure equipped with eight force/torque sensors that record quantitative data during the initiation of a predefined set of Activities of Daily Living (ADL) tasks, in isometric conditions. Preliminary results validated the appropriateness, acceptability and functionality of the proposed platform, that has become now a tool used for clinical research in three clinical centres. This paper presented the design and development of an innovative platform for whole-body force and torque measurements on human subjects. The platform has been designed to perform accurate quantitative measurements in isometric conditions with the specific aim to address the needs for functional assessment tests of patients undergoing a rehabilitation treatment as a consequence of a stroke.The versatility of the system also enlightens several other interesting possible areas of application for therapy in neurorehabilitation, for research in basic neuroscience, and more.

  11. Whole-body isometric force/torque measurements for functional assessment in neuro-rehabilitation: platform design, development and verification

    Directory of Open Access Journals (Sweden)

    Cavallo Giuseppe

    2009-10-01

    Full Text Available Abstract Background One of the main scientific and technological challenges of rehabilitation bioengineering is the development of innovative methodologies, based on the use of appropriate technological devices, for an objective assessment of patients undergoing a rehabilitation treatment. Such tools should be as fast and cheap to use as clinical scales, which are currently the daily instruments most widely used in the routine clinical practice. Methods A human-centered approach was used in the design and development of a mechanical structure equipped with eight force/torque sensors that record quantitative data during the initiation of a predefined set of Activities of Daily Living (ADL tasks, in isometric conditions. Results Preliminary results validated the appropriateness, acceptability and functionality of the proposed platform, that has become now a tool used for clinical research in three clinical centres. Conclusion This paper presented the design and development of an innovative platform for whole-body force and torque measurements on human subjects. The platform has been designed to perform accurate quantitative measurements in isometric conditions with the specific aim to address the needs for functional assessment tests of patients undergoing a rehabilitation treatment as a consequence of a stroke. The versatility of the system also enlightens several other interesting possible areas of application for therapy in neurorehabilitation, for research in basic neuroscience, and more.

  12. Unusual Wrist Tremor: Unilateral Isometric Tremor?

    Science.gov (United States)

    Zesiewicz, Theresa; Vu, Tuan; Carranza, Michael A.; Appelbaum, Rachel; Snyder, Madeline; Staffetti, Joseph S.; Allison, Kevin G.; Shimberg, William R.; Louis, Elan D.

    2014-01-01

    Background Tremors may be difficult to classify. Case Report An 83-year-old male presented with an unusual left wrist tremor. The tremor could be reproducibly elicited by making a fist or carrying a weighted object (e.g., a shopping bag, bottle of water) of approximately 1 lb or more, and it intensified with heavier weights. The tremor was difficult to classify, although it shared features with isometric tremor. Discussion This specific presentation of tremor has not been reported previously. We hope that the detailed description we provide will aid other neurologists who encounter this or similar tremors in their clinics. PMID:24455450

  13. Roughly isometric minimal immersions into Riemannian manifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    . In this talk we will mainly be concerned with {\\em{minimal}} isometric immersions of such geometrized approximations $(G, g)$ of $X$ into Riemannian manifolds $N$ with bounded curvature. When such an immersion exists, we will call it an $X$-web in $N$. Such webs admit a natural 'geometric' extension...... of the intrinsic combinatorial discrete Laplacian, and we will show that they share several analytic and geometric properties with their smooth (minimal submanifold) counterparts in $N$. The intrinsic properties thus obtained may hence serve as roughly invariant descriptors for the original metric space $X$....

  14. Isometric Reflection Vectors and Characterizations of Hilbert Spaces

    Directory of Open Access Journals (Sweden)

    Donghai Ji

    2014-01-01

    Full Text Available A known characterization of Hilbert spaces via isometric reflection vectors is based on the following implication: if the set of isometric reflection vectors in the unit sphere SX of a Banach space X has nonempty interior in SX, then X is a Hilbert space. Applying a recent result based on well-known theorem of Kronecker from number theory, we improve this by substantial reduction of the set of isometric reflection vectors needed in the hypothesis.

  15. Isometric exercises with elements postisometric relaxation to eliminate the knee joint contracture after arthroscopic plastics of anterior cruciate ligament

    Directory of Open Access Journals (Sweden)

    Pylypenko O.V.

    2014-02-01

    Full Text Available Purpose : to determine the efficiency of isometric exercises and post isometric relaxation of character for removal and prevention of contractures and recovery of motor function after arthroscopic reconstruction of the anterior cruciate ligament in the late postoperative period. Material: The study involved 22 patients aged less than 40 years. Results: The results showed that the level of pain decreased equally in patients of main and control group from 3 to 0 points, the performance difference in the amplitude of the bending of the knee joint during the goniometry in the treatment group was 70 in the control group – 30 and the extension 10 – fixed, reaching 5 hyperextension and not changed in the control group. Conclusions: The use of isometric exercises and post isometric relaxation prevent postoperative contracture of the knee joint. Methods of their application are recommended for use in the comprehensive rehabilitation of patients after arthroscopic plastics anterior cruciate ligament.

  16. Isometric and isokinetic muscle strength in patients with fibrositis syndrome. New characteristics for a difficult definable category of patients

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Danneskiold-Samsøe, B

    1987-01-01

    A common complaint among patients with fibrositis syndrome is exhaustion and fatique. It was therefore felt desirable to evaluate the muscle strength of these patients compared with normal subjects. Maximum isometric and isokinetic strength of knee extension was measured in 15 patients and 15...... in patients with fibrositis syndrome than in healthy subjects....

  17. Isometric knee-extensor torque development and jump height in volleyball players

    NARCIS (Netherlands)

    de Ruiter, C.J.; Vermeulen, G.; Toussaint, H.M.; de Haan, A.

    2007-01-01

    PURPOSE: The goal of the present study was to determine the contribution of the intrinsic muscle properties and muscle activation of the knee extensors to the maximal rate of unilateral isometric torque development and to relate both factors to maximal bilateral jumping performance in experienced

  18. Force levels in uni- and bimanual isometric tasks affect variability measures differently throughout lifespan.

    NARCIS (Netherlands)

    Smits-Engelsman, B.C.M.; Galen, G.P. van; Duysens, J.E.J.

    2004-01-01

    Ninety-four participants (age 5-93 years) performed isometric force production tasks at five different levels of their maximum voluntary contraction (MVC) with either one or two index fingers. Research questions were whether variability measures in the bimanual task condition were different compared

  19. Force levels in uni- and bimanual isometric tasks affect variability measures differently throughout lifespan

    NARCIS (Netherlands)

    Smits-Engelsman, B.C.M.; Galen, G.P. van; Duysens, J.E.J.

    2004-01-01

    Ninety-four participants (age 5-93 years) performed isometric force production tasks at five different levels of their maximum voluntary contraction (MVC) with either one or two index fingers. Research questions were whether variability measures in the bimanual task condition were different compared

  20. Effects of Isometric Hand-Grip Muscle Contraction on Young Adults' Free Recall and Recognition Memory

    Science.gov (United States)

    Tomporowski, Phillip D.; Albrecht, Chelesa; Pendleton, Daniel M.

    2017-01-01

    Purpose: The purpose of this study was to determine if physical arousal produced by isometric hand-dynamometer contraction performed during word-list learning affects young adults' free recall or recognition memory. Method: Twenty-four young adults (12 female; M[subscript age] = 22 years) were presented with 4 20-item word lists. Moderate arousal…

  1. Age-related decreases in motor unit discharge rate and force control during isometric plantar flexion

    DEFF Research Database (Denmark)

    Kallio, J; Søgaard, Karen; Avela, J

    2012-01-01

    Aging is related to multiple changes in muscle physiology and function. Previous findings concerning the effects of aging on motor unit discharge rate (DR) and fluctuations in DR and force are somewhat contradictory. Eight YOUNG and nine OLD physically active males performed isometric ramp (RECR)...

  2. Impact of glucose metabolism and birth size on cognitive performance in elderly subjects.

    Science.gov (United States)

    Paile-Hyvärinen, Maria; Räikkönen, Katri; Kajantie, Eero; Darby, David; Ylihärsilä, Hilkka; Salonen, Minna K; Osmond, Clive; Eriksson, Johan G

    2009-03-01

    We aimed to investigate the impact of diabetes and impaired glucose tolerance on cognitive performance and to explore the association between birth weight and cognitive performance among diabetic subjects. We performed a standard oral glucose tolerance test and a computerised test for assessment of cognitive performance (CogState) in 1243 subjects; 173 of them had type 2 diabetes. At the time of cognitive testing the mean age of the subjects was 64 years. Subjects with type 1 diabetes or a history of stroke were excluded. Subjects with known diabetes performed significantly poorer in cognitive tasks measuring visual attention, working memory and episodic learning than subjects with normal glucose tolerance. Subjects with newly diagnosed diabetes or milder impairments in glucose regulation did not differ from the normoglycaemic group. A low birth weight enhanced the association between diabetes and poor performance in the working memory and episodic learning tasks. Poorer cognitive performance was associated with known type 2 diabetes but not with newly diagnosed diabetes or milder impairments in glucose regulation. Low birth weight was found to be an additional vulnerability factor enhancing cognitive decline in diabetic subjects.

  3. Validity of an Isometric Midthigh Pull Dynamometer in Male Youth Athletes.

    Science.gov (United States)

    Till, Kevin; Morris, Rhys; Stokes, Keith; Trewartha, Grant; Twist, Craig; Dobbin, Nick; Hunwicks, Richard; Jones, Ben

    2017-11-16

    Till, K, Morris, R, Stokes, K, Trewartha, G, Twist, C, Dobbin, N, Hunwicks, R, and Jones, B. Validity of an isometric midthigh pull dynamometer in male youth athletes. J Strength Cond Res XX(X): 000-000, 2017-The purpose of this study was to investigate the validity of an isometric midthigh pull dynamometer against a criterion measure (i.e., 1,000-Hz force platform) for assessing muscle strength in male youth athletes. Twenty-two male adolescent (age 15.3 ± 0.5 years) rugby league players performed 4 isometric midthigh pull efforts (i.e., 2 on the dynamometer and 2 on the force platform) separated by 5-minute rest in a randomized and counterbalanced order. Mean bias, typical error of estimate (TEE), and Pearson correlation coefficient for peak force (PF) and peak force minus body weight (PFBW) from the force platform were validated against peak force from the dynamometer (DynoPF). When compared with PF and PFBW, mean bias (with 90% confidence limits) for DynoPF was very large (-32.4 [-34.2 to -30.6] %) and moderate (-10.0 [-12.8 to -7.2] %), respectively. The TEE was moderate for both PF (8.1 [6.3-11.2] %) and PFBW (8.9 [7.0-12.4]). Correlations between DynoPF and PF (r 0.90 [0.79-0.95]) and PFBW (r 0.90 [0.80-0.95]) were nearly perfect. The isometric midthigh pull assessed using a dynamometer underestimated PF and PFBW obtained using a criterion force platform. However, strong correlations between the dynamometer and force platform suggest that a dynamometer provides an appropriate alternative to assess isometric midthigh pull strength when a force platform is not available. Therefore, practitioners can use an isometric midthigh pull dynamometer to assess strength in the field with youth athletes but should be aware that it underestimates peak force.

  4. ISOMETRIC GLUTEUS MEDIUS MUSCLE TORQUE AND FRONTAL PLANE PELVIC MOTION DURING RUNNING

    Directory of Open Access Journals (Sweden)

    Evie N. Burnet

    2009-06-01

    Full Text Available The objective of this study was to investigate the relationship between isometric GM torque and the degree of frontal plane pelvic drop during running. Twenty-one healthy, recreational runners (9 males, 12 females who ran 8.05 km or more per week were obtained from a sample of convenience. GM maximal isometric torque was collected prior to the run. Subjects then ran on a treadmill for 30 minutes while bilateral three-dimensional pelvic kinematic data were collected for 10 seconds at each 2 minute increment. Left side pelvic drop showed a slight increase (effect size = 0.61; while, the right side pelvic drop remained stable (effect size = 0.18. Pearson's Correlations showed no relationship between GM isometric torque and frontal plane pelvic drop for any of the data collection periods during the 30-minute run. These results suggest that isometric GM torque was a poor predictor of frontal plane pelvic drop. One should question whether a dynamic rather than static measure of GM strength would be more appropriate. Future research is needed to identify dynamic strength measures that would better predict biomechanical components of running gait

  5. Pelvic floor muscle training decreases hip adductors isometric peak torque in incontinent women: an exploratory study

    Directory of Open Access Journals (Sweden)

    Grasiéla Nascimento Correia

    Full Text Available INTRODUCTION: The pelvic floor muscle (PFM training is the most common treatment for urinary incontinence (UI, however many women performed the contraction of PFM with associated contraction of abdominal, gluteus and hip adductors muscles. OBJECTIVE: To assess the effects of pelvic floor muscle (PFM training on isometric and isokinetic hip adductors peak torque (PT among women suffering from urinary incontinence (UI. MATERIALS AND METHODS: It is a longitudinal and prospective exploratory study. This study included 15 physically active women aged 45 years old and over, who presented complaints of UI. The PFM function (digital evaluation and perineometry, isometric and isokinetic hip adductors PT and one hour pad test were performed before and after treatment. The PFM training was performed in group, one hour once a week for 12 sessions. RESULTS: Significant improvement of PFM function and pressure level (p = 0.003, and significant decrease of hip adductors isometric PT and one-hour pad test, were found post-treatment. Moderate negative correlations between PFM contraction pressure and hip adductors isokinetic PT for dominant side (DS (r = -0.62; p = 0.03 and non-dominant side (NDS (r = -0.64; p = 0.02; and between PFM fast fibers contraction and hip adductors isometric PT for DS (r = -0.60; p = 0.03 and NDS (r = -0.59; p = 0.04 were also found. CONCLUSIONS: The PFM training decreased hip adductors PT and improved PFM functions and UI.

  6. Cutaneous mechanisms of isometric ankle force control

    DEFF Research Database (Denmark)

    Choi, Julia T; Jensen, Jesper Lundbye; Leukel, Christian

    2013-01-01

    The sense of force is critical in the control of movement and posture. Multiple factors influence our perception of exerted force, including inputs from cutaneous afferents, muscle afferents and central commands. Here, we studied the influence of cutaneous feedback on the control of ankle force...... output. We used repetitive electrical stimulation of the superficial peroneal (foot dorsum) and medial plantar nerves (foot sole) to disrupt cutaneous afferent input in 8 healthy subjects. We measured the effects of repetitive nerve stimulation on (1) tactile thresholds, (2) performance in an ankle force......-matching and (3) an ankle position-matching task. Additional force-matching experiments were done to compare the effects of transient versus continuous stimulation in 6 subjects and to determine the effects of foot anesthesia using lidocaine in another 6 subjects. The results showed that stimulation decreased...

  7. Effect of submaximal isometric wrist extension training on grip strength.

    Science.gov (United States)

    Shimose, Ryota; Matsunaga, Atsuhiko; Muro, Masuo

    2011-03-01

    Gripping force is produced by co-contraction of forearm flexors and extensors. Activation of extensors is important for stabilizing the wrist during gripping. However, forearm muscle function is complicated and the neurophysiological mechanism responsible for the gain in gripping force is unclear. Therefore, the purpose of this study was to investigate whether increasing forearm extensor activation with isometric wrist extension training has an effect on gripping force. Thirteen healthy subjects participated in this study. Maximal voluntary contraction of gripping was measured using a piezosensor (MVC(grip)) and EMG of forearm muscles at every wrist angle (from 70° flexion to 80° extension with 10° intervals) were measured simultaneously at baseline, 4 weeks, and 8 weeks after training. Training consisted of 30 repetitions equal to 70% MVC of isometric wrist extension for 8 weeks (5/week) on the right side. Gripping force was measured on both sides using a grip dynamometer without wrist angle restriction. Gripping force, EMG, maximal wrist extension force, and wrist angle-gripping force curve were investigated after training. After training, maximal wrist extension force increased significantly. Gripping force on the trained side also increased significantly. The training changed wrist angle at peak of MVC(grip). EMG activation of forearm extensors increased and that of flexors decreased during gripping. These results suggest that wrist extension training leads to an increase in gripping force and changes the balance of EMG activation between forearm flexors and extensors during gripping. Therefore, this training method should be useful as a therapeutic strategy for increasing grip strength.

  8. Measuring organizational performance in the hospital industry: an exploratory comparison of objective and subjective methods.

    Science.gov (United States)

    McCracken, M J; McIlwain, T F; Fottler, M D

    2001-11-01

    One of the major challenges facing health services management researchers is the measurement of various aspects of organizational performance. This challenge is exacerbated by a reluctance of many healthcare organizations to share data with researchers because of a fear of competitor access to these data. Even where objective, reliable and valid measures of organizational performance are available, typically they are available only in aggregate form, rather than for individual organizations. In response to these constraints, researchers have used subjective measures of performance often based on the perception of key executives. This research compares the subjective perceptions of hospital executives to the objective financial performance data of 60 hospitals. While the correlations between the subjective and objective measures vary, return of assets (ROA) and operating margin are the most valid subjective financial measures of hospital performance. Implications for future research are discussed.

  9. Predictability of maximum voluntary isometric knee extension force from submaximal contractions in older adults.

    Science.gov (United States)

    Stackhouse, Scott K; Stevens, Jennifer E; Johnson, Christopher D; Snyder-Mackler, Lynn; Binder-Macleod, Stuart A

    2003-01-01

    The purposes of this study were to develop and test a model describing the relationship between the central activation ratio (CAR; a measure of voluntary muscle activation) and percent maximum voluntary contraction (%MVC) force for old adults and to provide a method for more accurate determination of voluntary muscle activation failure. Twenty-one adults (ages 64-81) performed isometric testing of the quadriceps at 25%, 50%, 75%, and 100% MVC. During each contraction, a 100-HZ, 120-ms train of electrical pulses was delivered to the quadriceps muscle to quantify voluntary muscle activation. Similar to a young, healthy population (ages 20-35), a curvilinear relationship existed between the CAR and %MVC force for older adults. Predictions of subjects' MVCs using the linear model of CAR-%MVC force relationship generally demonstrated poor agreement with actual MVCs. Predictions of MVC from submaximal contractions (25%, 50%, and 75%) using a previously identified curvilinear young adult CAR-%MVC relationship were good [ICC (2,1): 0.81, 0.96, and 0.82, respectively]. Similar agreement was obtained from the curvilinear older adult CAR-%MVC relationship. These data suggest that the CAR-%MVC relationship is similar in young and older adult subjects and that curvilinear models of this relationship can predict MVC forces in older adults more accurately. Reexamination of the relationship between the CAR and %MVC force may allow a more accurate determination of how failure of voluntary muscle activation contributes to weakness in old adults.

  10. Dynamic Variability of Isometric Action Tremor in Precision Pinching

    Directory of Open Access Journals (Sweden)

    Tim Eakin

    2012-01-01

    Full Text Available Evolutionary development of isometric force impulse frequencies, power, and the directional concordance of changes in oscillatory tremor during performance of a two-digit force regulation task was examined. Analyses compared a patient group having tremor confounding volitional force regulation with a control group having no neuropathological diagnosis. Dependent variables for tremor varied temporally and spatially, both within individual trials and across trials, across individuals, across groups, and between digits. Particularly striking findings were magnitude increases during approaches to cue markers and shifts in the concordance phase from pinching toward rigid sway patterns as the magnitude increased. Magnitudes were significantly different among trace line segments of the task and were characterized by differences in relative force required and by the task progress with respect to cue markers for beginning, reversing force change direction, or task termination. The main systematic differences occurred during cue marker approach and were independent of trial sequence order.

  11. The Adaptive Range of 1/f Isometric Force Production

    Science.gov (United States)

    Sosnoff, Jacob J.; Valantine, Andrew D.; Newell, Karl M.

    2009-01-01

    The adaptive range of 1/f dynamics in isometric force output was investigated. Participants produced isometric force to targets with predictable demands (constant and sinusoidal) and 1/f noise waveforms (white, pink, brown, and black) that also varied in the frequency bandwidth represented in the force signal (0-4 Hz, 0-8 Hz, and 0-12 Hz). The…

  12. Neural and non-neural control of skin blood flow during isometric handgrip exercise in the heat stressed human

    DEFF Research Database (Denmark)

    Shibasaki, M.; Rasmussen, P.; Secher, Niels H.

    2009-01-01

    as an absence of sweating and cutaneous vasodilatation during a whole-body heat stress. Upon this confirmation, adenosine was perfused through one of the microdialysis probes to increase skin blood flow similar to that of the unblocked site. After internal temperature increased approximately 0.7 degrees C......During heat stress, isometric handgrip (IHG) exercise causes cutaneous vasoconstriction, but it remains controversial whether neural mechanisms are responsible for this observation. The objective of this study was to test the hypothesis that cutaneous vasoconstriction during IHG exercise in heat......, subjects performed 2 min of IHG exercise at 35% of maximal voluntary contraction using the non-blocked arm. IHG exercise significantly decreased CVC at the unblocked site (82.3 +/- 5.7 to 70.9 +/- 5.4%max, P = 0.005, means +/- S.E.M.) and the adenosine treated site of the blocked arm (75.2 +/- 7.2 to 68...

  13. Forward lunge as a functional performance test in ACL deficient subjects: test-retest reliability

    DEFF Research Database (Denmark)

    Alkjaer, Tine; Henriksen, Marius; Dyhre-Poulsen, Poul

    2009-01-01

    The forward lunge movement may be used as a functional performance test of anterior cruciate ligament (ACL) deficient and reconstructed subjects. The purposes were 1) to determine the test-retest reliability of a forward lunge in healthy subjects and 2) to determine the required numbers...

  14. Subjective Performance Evaluations, Self-esteem, and Ego-threats in Principal-agent Relations

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher; Walzl, Markus

    find that agents sanction whenever the feedback of principals is below their subjective self-evaluations even if the agents' payoff is independent of the principals' feedback. Based on our experimental analysis we propose a principal-agent model with subjective performance evaluations that accommodates...

  15. Stress and Performance: Effects of Subjective Work Load and Time Urgency.

    Science.gov (United States)

    Friend, Kenneth E.

    1982-01-01

    Measured subjective work load, time urgency, and other stress/motivation variables for management personnel taking a demanding problem-solving exam. Data suggest increases in psychological stresses like subjectively high work load and time urgency uniformly impair performance across the whole range of these variables. (Author)

  16. A method to evaluate performance reliability of individual subjects in laboratory research applied to work settings.

    Science.gov (United States)

    1978-10-01

    This report presents a method that may be used to evaluate the reliability of performance of individual subjects, particularly in applied laboratory research. The method is based on analysis of variance of a tasks-by-subjects data matrix, with all sc...

  17. Subjective user experience and performance with active tangibles on a tabletop interface

    NARCIS (Netherlands)

    Erp, J.B. van; Toet, A.; Meijer, K.; Janssen, J.; Jong, A. de

    2015-01-01

    We developed active tangibles (Sensators) that can be used in combination with multitouch tabletops and that can provide multisensory (visual, auditory, and vibrotactile) feedback. For spatial alignment and rotation tasks we measured subjective user experience and objective performance with these

  18. Subjective User Experience and Performance with Active Tangibles on a Tabletop Interfaces.

    NARCIS (Netherlands)

    van Erp, Johannes Bernardus Fransiscus; Toet, Alexander; Meijer, Koos; Janssen, Joris; Jong, Arnoud

    We developed active tangibles (Sensators) that can be used in combination with multitouch tabletops and that can provide multisensory (visual, auditory, and vibrotactile) feedback. For spatial alignment and rotation tasks we measured subjective user experience and objective performance with these

  19. Unusual Wrist Tremor: Unilateral Isometric Tremor?

    Directory of Open Access Journals (Sweden)

    Theresa A. Zesiewicz

    2014-01-01

    Full Text Available Background: Tremors may be difficult to classify.Case Report: An 83‐year‐old male presented with an unusual left wrist tremor. The tremor could be reproducibly elicited by making a fist or carrying a weighted object (e.g., a shopping bag, bottle of water of approximately 1 lb or more, and it intensified with heavier weights. The tremor was difficult to classify, although it shared features with isometric tremor.Discussion: This specific presentation of tremor has not been reported previously. We hope that the detailed description we provide will aid other neurologists who encounter this or similar tremors in their clinics.

  20. Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production.

    Science.gov (United States)

    Noorkõiv, Marika; Nosaka, Kazunori; Blazevich, Anthony J

    2015-01-01

    This study aims to (1) determine whether isometric training at a short vs. long quadriceps muscle length affects concentric torque production; (2) examine the relationship between muscle hypertrophy and concentric torque; and (3) determine whether changes in fascicle length are associated with changes in concentric torque. Sixteen men performed isometric training at a short (SL, n = 8) or a long muscle length (LL, n = 8). Changes in maximal concentric torque were measured at 30, 60, 90, 120, 180, 240 and 300 rad · s(-1). The relationships between the changes in concentric torque, cross-sectional area, volume and fascicle length were tested. Concentric torque increased significantly after training only in LL and at angular velocities of 30 and 120 rad · s(-1) by 12-13% (P Muscle size increased in LL only, the changes were correlated (r = 0.73-0.93, P torque. Vastus lateralis (VL) fascicle length increased in both groups (5.4 ± 4.9%, P = 0.001) but the change was not correlated with changes in concentric torque in either group. Isometric training-induced increases in muscle size and concentric torque were best elicited by training at long muscle lengths. These results highlight a clear muscle length dependence of isometric training on dynamic torque production.

  1. How isometric are the medial patellofemoral, superficial medial collateral, and lateral collateral ligaments of the knee?

    Science.gov (United States)

    Victor, Jan; Wong, Pius; Witvrouw, Eric; Sloten, Jos Vander; Bellemans, Johan

    2009-10-01

    Ligament isometry is a cornerstone in the description of normal knee function and thorough knowledge is mandatory for successful repair of torn ligaments. This study was undertaken to validate a novel experimental model for the study of ligament strains and to determine the length changes in the superficial medial collateral, lateral collateral, and medial patellofemoral ligaments. Descriptive laboratory study. Passive motions and loaded squats of 12 cadaveric specimens were performed while controlling ankle load and optically tracking the motion of the bones. Preexperiment and postexperiment computed axial tomography scans allow the transformation of rigid body motion to relative motion of relevant anatomic landmarks on the femur, tibia, and patella. The superficial medial collateral ligament is a near-isometric ligament with a strain of less than 2%. The ligament is a little more slack in midflexion (30 degrees to 50 degrees ) and in deep flexion, but length changes are not significant (P > .05). The lateral collateral ligament behaves near isometric (tension from the collateral ligaments (P superficial medial collateral ligament is a near-isometric ligament with no significant length changes. The medial patellofemoral ligament behaves differently in its cranial and caudal parts. In knees with chronic medial collateral ligament insufficiency, isometric repair of the superficial medial collateral ligament can be attempted. A medial patellofemoral ligament reconstruction with a double fixation on the medial patellar border is supported. The cranial bundle should be tightened at full extension and the caudal bundle at 30 degrees of knee flexion.

  2. Force variability during isometric wrist flexion in highly skilled and sedentary individuals.

    Science.gov (United States)

    Salonikidis, Konstantinos; Amiridis, Ioannis G; Oxyzoglou, Nikolaos; de Villareal, Eduardo Saez Saez; Zafeiridis, Andreas; Kellis, Eleftherios

    2009-12-01

    The association of expertness in specific motor activities with a higher ability to sustain a constant application of force, regardless of muscle length, has been hypothesized. Ten highly skilled (HS group) young tennis and handball athletes and 10 sedentary (S group) individuals performed maximal and submaximal (5, 10, 20, 50, and 75% of the MVC) isometric wrist flexions on an isokinetic dynamometer (Kin-Com, Chattanooga). The wrist joint was fixed at five different angles (230, 210, 180, 150, and 1300). For each position the percentages of the maximal isometric force were calculated and participants were asked to maintain the respective force level for 5 s. Electromyographic (EMG) activation of the Flexor Carpi Ulnaris and Extensor Digitorum muscles was recorded using bipolar surface electrodes. No significant differences were observed in maximal isometric strength between HS and S groups. Participants of HS group showed significantly (P wrist angles. The CV and SD values remained unaltered regardless of wrist angle. No difference in normalized agonist and antagonist EMG activity was observed between the two groups. It is concluded that long-term practice could be associated with decreased isometric force variability independently from muscular length and coactivation of the antagonist muscles.

  3. Predicting subjective vitality and performance in sports: the role of passion and achievement goals.

    Science.gov (United States)

    Li, Chiung-Huang

    2010-06-01

    The major purpose of this study was to test the hypothesized paths from dualistic passions through achievement goals to subjective vitality and performance in sports. 645 high school athletes participated. The proposed structural equation model, with relationships between dualistic passions and subjective vitality and sports performance mediated by achievement goals, fit the data well, especially for mastery-approach and performance-approach goals. Harmonious and obsessive passions may lead athletes to high performance via the adoption of mastery-approach goals. However, these passions seem to have two paths influencing personal functioning: direct effects make players feel energetic, and indirect effects on subjective vitality through adoption of mastery-approach and performance-approach goals.

  4. Effects of isotonic and isometric exercises with mist sauna bathing on cardiovascular, thermoregulatory, and metabolic functions

    Science.gov (United States)

    Iwase, Satoshi; Kawahara, Yuko; Nishimura, Naoki; Nishimura, Rumiko; Sugenoya, Junichi; Miwa, Chihiro; Takada, Masumi

    2014-08-01

    To clarify the effects of isometric and isotonic exercise during mist sauna bathing on the cardiovascular function, thermoregulatory function, and metabolism, six healthy young men (22 ± 1 years old, height 173 ± 4 cm, weight 65.0 ± 5.0 kg) were exposed to a mist sauna for 10 min at a temperature of 40 °C, and relative humidity of 100 % while performing or not performing ˜30 W of isometric or isotonic exercise. The effect of the exercise was assessed by measuring tympanic temperature, heart rate, systolic and diastolic blood pressure, chest sweat rate, chest skin blood flow, and plasma catecholamine and cortisol, glucose, lactate, and free fatty acid levels. Repeated measures ANOVA showed no significant differences in blood pressure, skin blood flow, sweat rate, and total amount of sweating. Tympanic temperature increased more during isotonic exercise, and heart rate increase was more marked during isotonic exercise. The changes in lactate indicated that fatigue was not very great during isometric exercise. The glucose level indicated greater energy expenditure during isometric exercise. The free fatty acid and catecholamine levels indicated that isometric exercise did not result in very great energy expenditure and stress, respectively. The results for isotonic exercise of a decrease in lactate level and an increase in plasma free fatty acid level indicated that fatigue and energy expenditure were rather large while the perceived stress was comparatively low. We concluded that isotonic exercise may be a more desirable form of exercise during mist sauna bathing given the changes in glucose and free fatty acid levels.

  5. Maximal isometric strength of the cervical musculature in 100 healthy volunteers

    DEFF Research Database (Denmark)

    Jordan, A; Mehlsen, J; Bülow, P M

    1999-01-01

    A descriptive study involving maximal isometric strength measurements of the cervical musculature.......A descriptive study involving maximal isometric strength measurements of the cervical musculature....

  6. Static, dynamic balance and functional performance in subjects with and without plantar fasciitis

    Directory of Open Access Journals (Sweden)

    Geiseane Aguiar Gonçalves

    Full Text Available Abstract Introduction: Plantar fasciitis (PF is characterized by non-inflammatory degeneration and pain under the heel, and is one of the most common foot complaints. The compensations and adjustments made to decrease the discomfort caused by the disease are clinical findings and can be a factor that contributes to impaired balance and decreased functional performance. Objective: To compare functional performance as well as static and dynamic balance among subjects with and without PF. Methods: The sample consisted of 124 subjects of both sexes aged 20-60 years. Participants were divided into two groups: a bilateral PF group (PFG; n = 62 and a control group (CG, n = 62. The following outcomes were analyzed: static and dynamic balance (using functional tests and functional performance (using a questionnaire. We used Student’s t test for independent samples to compare variables between the groups. The alpha error was set at 0.05. Results: Subjects with PF showed greater impairment in their overall dynamic balance performance (p < 0.001 than the control group, except for left posteromedial movement (p = 0.19. The CG showed showed better functional performance (p < 0.001 than the PF group. There was no difference between groups for the variable static balance on stable (p = 0.160 and unstable surfaces (p = 0.085. Conclusion: Subjects with PF displayed smaller reach distances in the overall Star Excursion Balance Test (SEBT, demonstrating a deficit in dynamic balance and functional performance when compared with healthy subjects.

  7. Response of Coagulation Indices to Two Types of Exercise of Eccentric and Isometric in Male Bodybuilding Athletes

    Directory of Open Access Journals (Sweden)

    Maryam Azimpour

    2016-05-01

    Full Text Available Abstract Background and Objectives: Although activation of blood coagulation system in response to physical activity has been identified to some extent, but the contribution of eccentric activity in comparison with isometric activity as resistance exercise, is not clear yet. Therefore, this research was carried out with the purpose of investigating the effect of one session of eccentric and isometric resistance exercise on some coagulation factors in male bodybuilders. Methods: In this semi-experimental study, 28 volunteers were randomly selected from male bodybuilders and divided into two experimental groups and one control group. One of the experimental groups performed eccentric exercise [controlled return (extension of the elbow flexion movement involving an eccentric contraction] and another group performed isometric exercises (holding barbell while flexing elbows at 45 degrees. In order to assess coagulation indices, blood sampling was performed 15 minutes before and immediately after the exercise. Results: Thromboplastin and prothrombin times did not significantly change immediately after the exercise, but the number of platelets significantly increased in both isometric and eccentric types of exercise immediately after the exercise. Conclusion: The results of isometric and eccentric acute resistance exercise showed that the exercise had no negative impact on blood coagulation factors, and increased coagulation system activity reflects the increased number of platelets. The difference between the results of researches carried out in this direction can be resulted from the difference between the exercise protocols, methods and measurement time, and level of preparedness of the participants in the research.

  8. Multiple Image Arrangement for Subjective Quality Assessment

    Science.gov (United States)

    Wang, Yan; Zhai, Guangtao

    2017-12-01

    Subjective quality assessment serves as the foundation for almost all visual quality related researches. Size of the image quality databases has expanded from dozens to thousands in the last decades. Since each subjective rating therein has to be averaged over quite a few participants, the ever-increasing overall size of those databases calls for an evolution of existing subjective test methods. Traditional single/double stimulus based approaches are being replaced by multiple image tests, where several distorted versions of the original one are displayed and rated at once. And this naturally brings upon the question of how to arrange those multiple images on screen during the test. In this paper, we answer this question by performing subjective viewing test with eye tracker for different types arrangements. Our research indicates that isometric arrangement imposes less duress on participants and has more uniform distribution of eye fixations and movements and therefore is expected to generate more reliable subjective ratings.

  9. Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.

    Science.gov (United States)

    Tanaka, Hiroki; Ikezoe, Tome; Umehara, Jun; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Nishishita, Satoru; Fujita, Kosuke; Araki, Kojiro; Ichihashi, Noriaki

    2016-11-01

    Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.

  10. The effects of energy drink in combination with alcohol on performance and subjective awareness

    OpenAIRE

    Alford, Chris; Hamilton-Morris, Jennifer; Verster, Joris C

    2012-01-01

    Rationale This study investigated the coadministration of an energy drink with alcohol to study the effects on subjective intoxication and objective performance. Objectives This study aims to evaluate the objective and subjective effects of alcohol versus placebo at two alcohol doses, alone and in combination with an energy drink, in a balanced order, placebo-controlled, double-blind design. Methods Two groups of ten healthy volunteers, mean (SD) age of 24 (6.5), participated in the study. On...

  11. Subjective trust, perceived risk and exchange performance in buyer-supplier relationships

    OpenAIRE

    Emanuela Delbufalo

    2012-01-01

    This article offers some theoretical and empirical contributions to the literature on relational exchange by examining the nature of subjective trust and perceived risk in buyer-supplier relationships. The relational view represents the theoretical framework for the research. The study explores the theoretical proposition that subjective trust and perceived risk in buyer-supplier relationships impact on exchange performance through the mediating effects of four sources of relational rents: as...

  12. Improved automated perimetry performance in elderly subjects after listening to Mozart

    Directory of Open Access Journals (Sweden)

    Junia Cabral Marques

    2009-01-01

    Full Text Available PURPOSE: To evaluate the performance of automated perimetry of elderly subjects naïve to AP after listening to a Mozart sonata. INTRODUCTION: Automated perimetry (AP is a psychophysical test used to assess visual fields in patients with neurological disorders and glaucoma. In a previous study, Fiorelli et al. showed that young subjects who listened to a Mozart sonata prior to undergoing AP performed better in terms of reliability than those who did not listen to the sonata. METHODS: Fifty-two AP-naïve, normal subjects underwent Automated perimetry (SITA 24-2. The study group (25 subjects underwent AP after listening to Mozart's Sonata for Two Pianos in D Major, and the control group (27 subjects underwent Automated perimetry without prior exposure to the music. RESULTS: The study group had significantly lower false negative rates and a lower visual field reliability score than the controls (P=0.04 and P=0.04, respectively. The test time was shorter for the study group (P=0.03. DISCUSSION: This study shows that elderly subjects, when exposed to the Mozart sonata immediately before AP testing, have lower false negative rates and lower visual field reliability scores when compared with an age- and gender-matched control group. Our results differ from those of Fiorelli et al. who found lower false positive rates and less fixation loss in addition to lower false negative rates. CONCLUSION: Listening to a Mozart sonata seems to improve automated perimetry reliability in elderly subjects.

  13. Improved automated perimetry performance in elderly subjects after listening to Mozart.

    Science.gov (United States)

    Marques, Junia Cabral; Vanessa, Adriana Chaves Oliveira; Fiorelli, Macedo Batista; Kasahara, Niro

    2009-01-01

    To evaluate the performance of automated perimetry of elderly subjects naïve to AP after listening to a Mozart sonata. Automated perimetry (AP) is a psychophysical test used to assess visual fields in patients with neurological disorders and glaucoma. In a previous study, Fiorelli et al. showed that young subjects who listened to a Mozart sonata prior to undergoing AP performed better in terms of reliability than those who did not listen to the sonata. Fifty-two AP-naïve, normal subjects underwent Automated perimetry (SITA 24-2). The study group (25 subjects) underwent AP after listening to Mozart's Sonata for Two Pianos in D Major, and the control group (27 subjects) underwent Automated perimetry without prior exposure to the music. The study group had significantly lower false negative rates and a lower visual field reliability score than the controls (P=0.04 and P=0.04, respectively). The test time was shorter for the study group (P=0.03). This study shows that elderly subjects, when exposed to the Mozart sonata immediately before AP testing, have lower false negative rates and lower visual field reliability scores when compared with an age- and gender-matched control group. Our results differ from those of Fiorelli et al. who found lower false positive rates and less fixation loss in addition to lower false negative rates. Listening to a Mozart sonata seems to improve automated perimetry reliability in elderly subjects.

  14. Effects of Contract-Relax, Static Stretching, and Isometric Contractions on Muscle-Tendon Mechanics.

    Science.gov (United States)

    Kay, Anthony D; Husbands-Beasley, Jade; Blazevich, Anthony J

    2015-10-01

    Loading characteristics of stretching techniques likely influence the specific mechanisms responsible for acute increases in range of motion (ROM). Therefore, the effects of a version of contract-relax (CR) proprioceptive neuromuscular facilitation stretching, static stretching (SS), and maximal isometric contraction (Iso) interventions were studied in 17 healthy human volunteers. Passive ankle moment was recorded on an isokinetic dynamometer, with EMG recording from the triceps surae, simultaneous real-time motion analysis, and ultrasound-imaging-recorded gastrocnemius medialis muscle and Achilles tendon elongation. Subjects then performed each intervention randomly on separate days before reassessment. Significant increases in dorsiflexion ROM (2.5°-5.3°; P stretching (P stretching and Iso (17.7%-22.1%; P 0.05), whereas significant reductions in muscle stiffness occurred after CR stretching and SS (16.0%-20.5%; P 0.05). Increases in peak passive moment (stretch tolerance) occurred after Iso (6.8%; P stretching (10.6%; P = 0.08), and SS (5.2%; P = 0.08); no difference in changes between conditions was found (P > 0.05). Significant correlations (rs = 0.69-0.82; P stretching suggest a broader adaptive response that likely explains its superior efficacy in acutely increasing ROM. Although mechanical changes appear tissue-specific between interventions, similar increases in stretch tolerance after all interventions are strongly correlated with changes in ROM.

  15. Isometric knee extensor fatigue following a Wingate test: peripheral and central mechanisms.

    Science.gov (United States)

    Fernandez-del-Olmo, M; Rodriguez, F A; Marquez, G; Iglesias, X; Marina, M; Benitez, A; Vallejo, L; Acero, R M

    2013-02-01

    Central and peripheral fatigue have been explored during and after running or cycling exercises. However, the fatigue mechanisms associated with a short maximal cycling exercise (30 s Wingate test) have not been investigated. In this study, 10 volunteer subjects performed several isometric voluntary contractions using the leg muscle extensors before and after two bouts of cycling at 25% of maximal power output and two bouts of Wingate tests. Transcranial magnetic stimulation (TMS) and electrical motor nerve stimulation (NM) were applied at rest and during the voluntary contractions. Maximal voluntary contraction (MVC), voluntary activation (VA), twitch amplitude evoked by electrical nerve stimulation, M wave and motor potential evoked by TMS (MEP) were recorded. MVC, VA and twitch amplitude evoked at rest by NM decreased significantly after the first and second Wingate tests, indicating central and peripheral fatigue. MVC and VA, but not the twitch amplitude evoked by NM, recovered before the second Wingate test. These results suggest that the Wingate test results in a decrease in MVC associated with peripheral and central fatigue. While the peripheral fatigue is associated with an intramuscular impairment, the central fatigue seems to be the main reason for the Wingate test-induced impairment of MVC. © 2011 John Wiley & Sons A/S.

  16. A Comparison of Tandem Walk Performance Between Bed Rest Subjects and Astronauts

    Science.gov (United States)

    Miller, Chris; Peters, Brian; Kofman, Igor; Philips, Tiffany; Batson, Crystal; Cerisano, Jody; Fisher, Elizabeth; Mulavara, Ajitkumar; Feiveson, Alan; Reschke, Millard; hide

    2015-01-01

    Astronauts experience a microgravity environment during spaceflight, which results in a central reinterpretation of both vestibular and body axial-loading information by the sensorimotor system. Subjects in bed rest studies lie at 6deg head-down in strict bed rest to simulate the fluid shift and gravity-unloading of the microgravity environment. However, bed rest subjects still sense gravity in the vestibular organs. Therefore, bed rest isolates the axial-unloading component, thus allowing for the direct study of its effects. The Tandem Walk is a standard sensorimotor test of dynamic postural stability. In a previous abstract, we compared performance on a Tandem Walk test between bed rest control subjects, and short- and long-duration astronauts both before and after flight/bed rest using a composite index of performance, called the Tandem Walk Parameter (TWP), that takes into account speed, accuracy, and balance control. This new study extends the previous data set to include bed rest subjects who performed exercise countermeasures. The purpose of this study was to compare performance during the Tandem Walk test between bed rest subjects (with and without exercise), short-duration (Space Shuttle) crewmembers, and long-duration International Space Station (ISS) crewmembers at various time points during their recovery from bed rest or spaceflight.

  17. Isometric muscle fatigue of the paravertebral and upper extremity muscles after whiplash injury.

    Science.gov (United States)

    Rastovic, Pejana; Gojanovic, Marija Definis; Berberovic, Marina; Pavlovic, Marko; Lesko, Josip; Galic, Gordan; Pandza, Maja

    2017-01-01

    Whiplash-associated disorders (WAD) result from injury of neck structures that most often occur during traffic accidents as a result of rapid acceleration-deceleration. The dominant symptoms manifest in the musculoskeletal system and include increased fatigue. Because of the frequency of whiplash injuries, a simple, cheap and useful diagnostic tool is needed to differentiate whiplash injury from healthy patients or those faking symptoms. To determine muscle fatigue in patients with whiplash injury in six body positions. Analytical cross-sectional study. Emergency center, university hospital. We studied patients with whiplash injury from vehicular traffic accidents who presented to the emergency center within 6 hours of sustaining the injury. We determined whiplash injury grade according to the Quebec Task Force (QTF) classification and measured isometric muscle endurance in six different body positions. Control subjects for each patient were matched by age, gender and anthropomorphic characteristics. Cut-off values were determined to distinguish patients with whiplash injury from controls and for determination of injury grade . QTF grade, time to muscle fatigue in seconds. From September 2013 to September 2016, we enrolled 75 patients with whiplash injury and 75 matching control subjects. In all six positions, the patients with whiplash injury felt muscle fatigue faster than equivalent controls (P muscle fatigue decreased with increasing injury grades in all six positions. Assignment to the patient or control group and to injury grade could be predicted with more than 90% accuracy on the basis of time to muscle fatigue. The most efficient position was the highest injury grade, by which 99.9% of the patients were accurately categorized. Isometric muscle endurance correlated with whiplash injury grade in all six positions (P muscle endurance and the appearance of isometric muscle fatigue during testing can be a useful indicator of whiplash injury and grade. The size

  18. Shoulder muscular activity during isometric three-point kneeling exercise on stable and unstable surfaces.

    Science.gov (United States)

    de Araújo, Rodrigo Cappato; de Andrade, Rodrigo; Tucci, Helga Tatiana; Martins, Jaqueline; de Oliveira, Anamaria Siriani

    2011-08-01

    The purpose of this study was to determine if performing isometric 3-point kneeling exercises on a Swiss ball influenced the isometric force output and EMG activities of the shoulder muscles when compared with performing the same exercises on a stable base of support. Twenty healthy adults performed the isometric 3-point kneeling exercises with the hand placed either on a stable surface or on a Swiss ball. Surface EMG was recorded from the posterior deltoid, pectoralis major, biceps brachii, triceps brachii, upper trapezius, and serratus anterior muscles using surface differential electrodes. All EMG data were reported as percentages of the average root mean square (RMS) values obtained in maximum voluntary contractions for each muscle studied. The highest load value was obtained during exercise on a stable surface. A significant increase was observed in the activation of glenohumeral muscles during exercises on a Swiss ball. However, there were no differences in EMG activities of the scapulothoracic muscles. These results suggest that exercises performed on unstable surfaces may provide muscular activity levels similar to those performed on stable surfaces, without the need to apply greater external loads to the musculoskeletal system. Therefore, exercises on unstable surfaces may be useful during the process of tissue regeneration.

  19. Effects of intra-set rest on the ability to repeat work at maximal isometric strength.

    Science.gov (United States)

    García Manso, Juan M; Valverde, Teresa; Arrones, Luis; Navarro-Valdivielso, Manuel; Martin Dantas, Estélio H; Da Silva-Grigoletto, Marzo E

    2016-03-01

    The aim of this paper was to analyze how the rest between interval repetitions in intra-set training (at maximal isometric loads) could affect the ability to repeat maximal contractions in subjects with different levels of performance and different experience in strength development work. Twenty subjects were divided randomly into two different groups depending on their sport characteristics: ten subjects were trained in strength development work (Group Strenght--23.1±4.6 years; 172.0±5.3 cm; 79.9±12.1 kg; 2175.6±490.8 N; 46.9±4.9 mL/kg.min), and ten subjects were trained in endurance work (Group Endurance--21.3±4.5 years; 172.4±4.1 cm; 60.0±4.6 kg; 815.5±206.5 N; 67.4±4.9 mL/kg.min). To assess the ability to repeat maximal efforts, 20 repetitions of 5 seconds were performed in a half-squat position, with 1 minute of rest between repetitions. For both groups, four different phases were observed in the Interval Maximal Force test during the 20-repetition assessment: potentiation, maintenance, moderate loss, and significant loss. For the GE, the loss in maximum strength capacity began in the fourth repetition (GS4th: 3.4%, ns, Effect Size: 0.09 vs. GE3th: 1.6%; ns; ES: 0.06) and reached a statistically significant value in the twelfth repetition (GS12th: 12.7%, P=0.03, ES: 0.35 vs. GE7th: 12.5%; P=0.01; ES: 0.49). The number of repetitions at which the strength began to decrease depended on the subject's sport characteristic and performance level. This study shows how an appropriate intra-set rest inclusion can significantly increase the work performed in every set without changing the muscle contraction characteristics, thus delaying muscle fatigue and maintaining the desired training objective.

  20. Speech perception performance of subjects with type I diabetes mellitus in noise

    Directory of Open Access Journals (Sweden)

    Bárbara Cristiane Sordi Silva

    Full Text Available Abstract Introduction: Diabetes mellitus (DM is a chronic metabolic disorder of various origins that occurs when the pancreas fails to produce insulin in sufficient quantities or when the organism fails to respond to this hormone in an efficient manner. Objective: To evaluate the speech recognition in subjects with type I diabetes mellitus (DMI in quiet and in competitive noise. Methods: It was a descriptive, observational and cross-section study. We included 40 participants of both genders aged 18-30 years, divided into a control group (CG of 20 healthy subjects with no complaints or auditory changes, paired for age and gender with the study group, consisting of 20 subjects with a diagnosis of DMI. First, we applied basic audiological evaluations (pure tone audiometry, speech audiometry and immittance audiometry for all subjects; after these evaluations, we applied Sentence Recognition Threshold in Quiet (SRTQ and Sentence Recognition Threshold in Noise (SRTN in free field, using the List of Sentences in Portuguese test. Results: All subjects showed normal bilateral pure tone threshold, compatible speech audiometry and "A" tympanometry curve. Group comparison revealed a statistically significant difference for SRTQ (p = 0.0001, SRTN (p < 0.0001 and the signal-to-noise ratio (p < 0.0001. Conclusion: The performance of DMI subjects in SRTQ and SRTN was worse compared to the subjects without diabetes.

  1. Isometric evaluation of rotator cuff muscles in volleyball athletes.

    Science.gov (United States)

    Martelli, G; Ciccarone, G; Grazzini, G; Signorini, M; Urgelli, S

    2013-06-01

    The aim of the present study was to evaluate, in a group of semi-professional volleyball players, the function of the rotator cuff muscles with a new specific device. We have studied 30 asymptomatic volleyball players, 15 females and 15 males, all right handed central or lateral spikers, with some specific functional tests. Every subject was evaluated by some common clinical tests to detect shoulder range of motion (ROM) and rotator cuff muscles strength in both sides. Athletes were also submitted to an isometric bilateral shoulder strength test, with a specific upper limb dynamometer (Dynatorq), in three different positions: 1) arm 0° abducted; 2) arm 90° abducted and 90° external rotation, to try to reproduce the spike gesture; 3) arm behind the thorax, as a simulation of clinical lift-off test. All clinical and instrumental data were collected in male and female groups and, in each group, comparisons between dominant and non dominant shoulders. Our data show in all athletes an initial postero-superior impingement with significant weakness of the subscapularis muscle in the dominant shoulder. In all overhead athletes, and in particular in volleyball spikers, a pre-clinical diagnosis of lack of strength of the subscapularis muscle in the dominant side, before the occurrence of pain or discomfort signs, could be an important diagnostic aspect to avoid or delay the back-retraction of the joint capsule of the shoulder.

  2. Assessment of pilot workload - Converging measures from performance based, subjective and psychophysiological techniques

    Science.gov (United States)

    Kramer, Arthur F.; Sirevaag, Erik J.; Braune, Rolf

    1986-01-01

    This study explores the relationship between the P300 component of the event-related brain potential (ERP) and the processing demands of a complex real-world task. Seven male volunteers enrolled in an Instrument Flight Rule (IFR) aviation course flew a series of missions in a single engine fixed-based simulator. In dual task conditions subjects were also required to discriminate between two tones differing in frequency. ERPs time-locked to the tones, subjective effort ratings and overt performance measures were collected during two 45 min flights differing in difficulty (manipulated by varying both atmospheric conditions and instrument reliability). The more difficult flight was associated with poorer performance, increased subjective effort ratings, and smaller secondary task P300s. Within each flight, P300 amplitude was negatively correlated with deviations from command headings indicating that P300 amplitude was a sensitive workload metric both between and within the flight missions.

  3. Motor performance during and following acute alcohol intoxication in healthy non-alcoholic subjects

    DEFF Research Database (Denmark)

    Poulsen, Mette Buch; Jakobsen, Johannes Klitgaard; Andersen, Henning

    2007-01-01

    Chronic alcohol abuse has adverse effects on skeletal muscle, and reduced muscle strength is frequently seen in chronic alcoholics. In this study the acute effects of moderate alcohol intoxication on motor performance was evaluated in 19 non-alcoholic healthy subjects (10 women, 9 men). A randomi...... of moderate alcohol intoxication (1,4 g/l) does not impair motor performance, and no accelerated exercise-induced muscle damage is seen. Udgivelsesdato: 2007-Nov...

  4. Associations of maximal voluntary isometric hip extension torque with muscle size of hamstring and gluteus maximus and intra-abdominal pressure.

    Science.gov (United States)

    Tayashiki, Kota; Hirata, Kosuke; Ishida, Kiraku; Kanehisa, Hiroaki; Miyamoto, Naokazu

    2017-06-01

    Muscle size of the hamstring and gluteus maximus (GM) as well as intra-abdominal pressure (IAP) are considered as factors affecting the torque development during hip extension. This study examined the associations of torque development during maximal voluntary isometric hip extension with IAP and muscle size of the hamstring and GM. Anatomical cross-sectional area (ACSA) of the hamstring and thickness of GM were determined in 20 healthy young males using an ultrasonography apparatus (Experiment 1). Torque and IAP were simultaneously measured while subjects performed maximal voluntary isometric hip extension. The IAP was measured using a pressure transducer placed in the rectum and determined at the time at which the developed torque reached to the maximal. In Experiment 2, torque and IAP were measured during maximal voluntary isometric hip flexion in 18 healthy young males. The maximal hip extension torque was significantly correlated with the IAP (r = 0.504, P = 0.024), not with the ACSA of the hamstring (r = 0.307, P = 0.188) or the thickness of GM (r = 0.405, P = 0.076). The relationship was still significant even when the ACSA of the hamstring and the thickness of GM were adjusted statistically (r = 0.486, P = 0.041). The maximal hip flexion torque was not significantly correlated with the IAP (r = -0.118, P = 0.642). The current results suggest that IAP can contribute independently of the muscle size of the agonists to maximal voluntary hip extension torque.

  5. Student Performance on the NBME Part II Subtest and Subject Examination in Obstetrics-Gynecology.

    Science.gov (United States)

    Metheny, William P.; Holzman, Gerald B.

    1988-01-01

    Comparison of the scores of 342 third-year medical students on the National Board of Medical Examiners subject examination and the Part II subtest on obstetrics-gynecology found significantly better performance on the former, suggesting a need to interpret the scores differently. (Author/MSE)

  6. Cervical isometric strength and range of motion of elite rugby union players: a cohort study

    OpenAIRE

    Hamilton, David F.; Gatherer, Don

    2014-01-01

    BACKGROUND: Head and neck injury is relatively common in Rugby Union. Despite this, strength and range-of-motion characteristics of the cervical spine are poorly characterised. The aim of this study was to provide data on the strength and range-of-motion of the cervical spine of professional rugby players to guide clinical rehabilitation.METHODS: A cohort study was performed evaluating 27 players from a single UK professional rugby club. Cervical isometric strength and range-of-motion were as...

  7. Isometric handgrip does not elicit cardiovascular overload or post-exercise hypotension in hypertensive older women.

    Science.gov (United States)

    Olher, Rafael dos Reis Vieira; Bocalini, Danilo Sales; Bacurau, Reury Frank; Rodriguez, Daniel; Figueira, Aylton; Pontes, Francisco Luciano; Navarro, Francisco; Simões, Herbert Gustavo; Araujo, Ronaldo Carvalho; Moraes, Milton Rocha

    2013-01-01

    Arterial hypertension is a serious health problem affecting mainly the elderly population. Recent studies have considered both aerobic and resistance exercises as a non-pharmacological aid for arterial hypertension treatment. However, the cardiovascular responses of the elderly to isometric resistance exercise (eg, isometric handgrip [IHG]) have not yet been documented. The purpose of this study was to investigate cardiovascular responses to different intensities of isometric exercise, as well as the occurrence of post-isometric exercise hypotension in hypertensive elderly people under antihypertensive medication treatment. Twelve women volunteered to participate in the study after a maximal voluntary contraction test (MVC) and standardization of the intervention workload consisting of two sessions of IHG exercise performed in four sets of five contractions of a 10-second duration. Sessions were performed both at 30% of the MVC and 50% of the MVC, using a unilateral IHG protocol. Both intensities were compared with a control session without exercise. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) at rest (R), during peak exercise (PE), and after 5, 10, 15, 30, 45, and 60 minutes of post-exercise recovery were evaluated. No significant changes were observed after isometric exercise corresponding to 30% MVC for either SBP (R: 121 ± 10; PE: 127 ± 14; 5 min: 125 ± 13; 10 min: 123 ± 12; 15 min: 122 ± 11; 30 min: 124 ± 11; 45 min: 124 ± 10; 60 min: 121 ± 10 mmHg) or DBP (R: 74 ± 9; PE: 76 ± 6; 5 min: 74 ± 5; 10 min: 72 ± 8; 15 min: 72 ± 5; 30 min: 72 ± 8; 45 min: 73 ± 6; 60 min: 75 ± 7 mmHg). Similarly, the 50% MVC did not promote post-isometric exercise hypotension for either SBP (R: 120 ± 7; PE: 125 ± 11; 5 min: 120 ± 9; 10 min: 122 ± 9; 15 min: 121 ± 11; 30 min: 121 ± 9; 45 min: 121 ± 9; 60 min: 120 ± 7 mmHg) or DBP (R: 72 ± 8; PE: 78 ± 7; 5 min: 72 ± 7; 10 min: 72 ± 8; 15 min: 71 ± 7; 30 min: 72 ± 8; 45 min: 75 ± 10

  8. Multimodal decoding and congruent sensory information enhance reaching performance in subjects with cervical spinal cord injury

    Directory of Open Access Journals (Sweden)

    Elaine Anna Corbett

    2014-05-01

    Full Text Available Cervical spinal cord injury (SCI paralyzes muscles of the hand and arm, making it difficult to perform activities of daily living. Restoring the ability to reach can dramatically improve quality of life for people with cervical SCI. Any reaching system requires a user interface to decode parameters of an intended reach, such as trajectory and target. A challenge in developing such decoders is that often few physiological signals related to the intended reach remain under voluntary control, especially in patients with high cervical injuries. Furthermore, the decoding problem changes when the user is controlling the motion of their limb, as opposed to an external device. The purpose of this study was to investigate the benefits of combining disparate signal sources to control reach in people with a range of impairments, and to consider the effect of two feedback approaches. Subjects with cervical SCI performed robot-assisted reaching, controlling trajectories with either shoulder electromyograms (EMGs or EMGs combined with gaze. We then evaluated how reaching performance was influenced by task-related sensory feedback, testing the EMG-only decoder in two conditions. The first involved moving the arm with the robot, providing congruent sensory feedback through their remaining sense of proprioception. In the second, the subjects moved the robot without the arm attached, as in applications that control external devices. We found that the multimodal decoding algorithm worked well for all subjects, enabling them to perform straight, accurate reaches. The inclusion of gaze information, used to estimate target location, was especially important for the most impaired subjects. In the absence of gaze information, congruent sensory feedback improved performance. These results highlight the importance of proprioceptive feedback, and suggest that multi-modal decoders are likely to be most beneficial for highly impaired subjects and in tasks where such

  9. Comparison of Maximal Lingual Pressure Generation During Isometric Gross and Fine Sensorimotor Tasks in Healthy Adults.

    Science.gov (United States)

    Rogus-Pulia, Nicole; Churness, Kim; Hind, Jacqueline; Gangnon, Ronald; Banaszynski, Kelsey; Robbins, JoAnne

    2015-10-01

    To (1) compare 2 distinct isometric lingual press tasks, fine sensorimotor versus gross sensorimotor, at multiple sensor locations in relation to age and sex; and (2) provide a normative data set using a lingual-strengthening device. Cohort study. University. Healthy men and women (N=71; age range, 21-82y) recruited from the community. Participants were stratified by age and sex and divided into 3 age groups. Participants completed, in random order, 2 isometric tasks: (1) fine sensorimotor: tongue press maximally and discreetly against each of 5 sensors; and (2) gross sensorimotor: tongue press maximally against all 5 sensors simultaneously. Primary outcome was maximum isometric pressure in hectopascals (hPa). Secondary outcomes were time to reach peak pressure (s) and pressure gradient (hPa/s). Maximum pressures were significantly lower in those of older age for both fine and gross sensorimotor lingual tasks (Psensorimotor task generating higher pressures at the front sensor for all age groups. However, the gross sensorimotor task generated faster maximum pressures at all sensor locations for all age groups. For both sensorimotor tasks, subjects of older age as a whole generated less steep pressure gradients (Psensorimotor task may be more beneficial for targeting timing as a biomechanical parameter during therapy, and the fine sensorimotor task may be more beneficial for targeting strength. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  10. Muscle activity of the erector spinae during Pilates isometric exercises on and off Swiss Ball.

    Science.gov (United States)

    Paz, G; Maia, M; Santiago, F; Lima, V; Miranda, H

    2014-10-01

    The purpose of this study was to investigate the muscle activity of the Erector spinae (ES) during Pilates isometric exercises on and off Swiss ball. Fifteen women (22.9±2.1years, 171.7±4.7 cm, 65.7±5.3 kg and 11.2±3.2% of body fat) with previous Pilates experience (1±0.9 years) participated as subjects in this study. In the first test session, the anthropometric data and maximal voluntary contraction (MVC) was measured. In the second test session, three isometric exercises were conducted on and off the Swiss ball: back extension (BE), back extension with elbows flexed (BTF) and back extension with elbows extended (BTE). During all exercises, average integrated electromyography (IEMG) from ES muscle was collected and analyzed. A one-way ANOVA with repeated measures followed by Bonferroni post hoc was adopted to compare the muscle activity (PSwiss ball, respectively. Significant differences were observed for the ES activity during BTE exercise when compared to BTF and BT on and off Swiss ball, respectively. The Swiss ball may not provide a potential effect on ES activity during Pilates isometric exercises with similar posture when compared to stable surfaces. Therefore, the combination of BT, BTF and BTE exercises may be an interesting alternative to provide progressive increases in the ES activity.

  11. Improved Automated Perimetry Performance in Elderly Subjects after Listening To Mozart

    Science.gov (United States)

    Marques, Junia Cabral; Vanessa, Adriana Chaves Oliveira; Fiorelli, Macedo Batista; Kasahara, Niro

    2009-01-01

    PURPOSE: To evaluate the performance of automated perimetry of elderly subjects naïve to AP after listening to a Mozart sonata. INTRODUCTION: Automated perimetry (AP) is a psychophysical test used to assess visual fields in patients with neurological disorders and glaucoma. In a previous study, Fiorelli et al. showed that young subjects who listened to a Mozart sonata prior to undergoing AP performed better in terms of reliability than those who did not listen to the sonata. METHODS: Fifty-two AP-naïve, normal subjects underwent Automated perimetry (SITA 24-2). The study group (25 subjects) underwent AP after listening to Mozart’s Sonata for Two Pianos in D Major, and the control group (27 subjects) underwent Automated perimetry without prior exposure to the music. RESULTS: The study group had significantly lower false negative rates and a lower visual field reliability score than the controls (P=0.04 and P=0.04, respectively). The test time was shorter for the study group (P=0.03). DISCUSSION: This study shows that elderly subjects, when exposed to the Mozart sonata immediately before AP testing, have lower false negative rates and lower visual field reliability scores when compared with an age- and gender-matched control group. Our results differ from those of Fiorelli et al. who found lower false positive rates and less fixation loss in addition to lower false negative rates. CONCLUSION: Listening to a Mozart sonata seems to improve automated perimetry reliability in elderly subjects. PMID:19606243

  12. Monocular and binocular reading performance in subjects with normal binocular vision.

    Science.gov (United States)

    Johansson, Jan; Pansell, Tony; Ygge, Jan; Seimyr, Gustaf Öqvist

    2014-07-01

    It is well known that problems with binocular vision can cause issues for reading; less known is to what extent binocular vision improves reading performance. The purpose of this study was to explore the role of binocularity by directly comparing monocular and binocular reading in subjects with typical reading skills and normal binocular vision. A secondary purpose was to assess any asymmetry in monocular performance and its association with the sighting dominant eye. In a balanced repeated measures experiment, 18 subjects read paragraphs of text under monocular and binocular conditions. All subjects went through an optometric examination before inclusion. Reading speed and eye movements were recorded with an eye tracker. The mean difference in reading speed (2.1 per cent) between monocular (dominant and non-dominant eye averaged) and binocular reading speed was not significant. A significant difference in reading speed was found between binocular and the non-dominant eye, as determined by the far sighting test (p = 0.03). Monocular reading showed significantly increased (8.9 per cent) fixation duration (p binocular vision, there is no marked enhancement in reading performance by binocular vision when reading paragraphs of text. Furthermore, the monocular reading performance appears to be close to equal and any small differences in performance appear not to be strongly associated with ocular dominance. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

  13. Precompetitive state anxiety, objective and subjective performance, and causal attributions in competitive swimmers.

    Science.gov (United States)

    Polman, Remco; Rowcliffe, Naomi; Borkoles, Erika; Levy, Andrew

    2007-02-01

    This study investigated the nature of the relationship between precompetitive state anxiety (CSAI-2C), subjective (race position) and objective (satisfaction) performance outcomes, and self-rated causal attributions (CDS-IIC) for performance in competitive child swimmers. Race position, subjective satisfaction, self-confidence, and, to a lesser extent, cognitive state anxiety (but not somatic state anxiety) were associated with the attributions provided by the children for their swimming performance. The study partially supported the self-serving bias hypothesis; winners used the ego-enhancing attributional strategy, but the losers did not use an ego-protecting attributional style. Age but not gender appeared to influence the attributions provided in achievement situations.

  14. Single subject analyses reveal consistent recruitment of frontal operculum in performance monitoring.

    Science.gov (United States)

    Amiez, Céline; Wutte, Magdalena G; Faillenot, Isabelle; Petrides, Michael; Burle, Boris; Procyk, Emmanuel

    2016-06-01

    There are continuing uncertainties regarding whether performance monitoring recruits the anterior insula (aI) and/or the frontal operculum (fO). The proximity and morphological complexity of these two regions make proper identification and isolation of the loci of activation extremely difficult. The use of group averaging methods in human neuroimaging might contribute to this problem. The result has been heterogeneous labeling of this region as aI, fO, or aI/fO, and a discussion of results oriented towards either cognitive or interoceptive functions depending on labeling. In the present article, we adapted the spatial preprocessing of functional magnetic resonance imaging data to account for group averaging artifacts and performed a subject-by-subject analysis in three performance monitoring tasks. Results show that functional activity related to feedback or action monitoring consistently follows local morphology in this region and demonstrate that the activity is located predominantly in the fO rather than in the aI. From these results, we propose that a full understanding of the respective role of aI and fO would benefit from increased spatial resolution and subject-by-subject analysis. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Subjective Evaluation of Packet Service Performance in UMTS and Heterogeneous Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Sørensen, Troels Bundgaard; Mogensen, Preben

    2006-01-01

    Quality of Service (QoS) in mobile telecommunication systems is usually identified by some basic performance metrics such as delay, throughput and jitter. However, the main impact of service quality is on the end user, and as such a detailed study of service performance should involve the end user....... In this paper, such an approach is taken where subjective performance evaluation is undertaken for web browsing and video streaming services in Universal Mobile Telecommunication System (UMTS) and a heterogeneous network comprised of UMTS and Wireless LAN (WLAN). Using a real-time network emulation testbed...

  16. Performance effects and subjective disturbance of speech in acoustically different office types--a laboratory experiment.

    Science.gov (United States)

    Haka, M; Haapakangas, A; Keränen, J; Hakala, J; Keskinen, E; Hongisto, V

    2009-12-01

    This study examined how the intelligibility of irrelevant speech, determined with the Speech Transmission Index (STI), affects demanding cognitive task performance. Experiment was carried out in a laboratory that resembled an open-plan office. Three speech conditions were tested corresponding to a private office (STI = 0.10), an acoustically excellent open office (STI = 0.35) and an acoustically poor open office (STI = 0.65). All conditions were presented at equal level, 48 dBA. The STI was adjusted by the relative levels of speech and masking sound. Thirty-seven students participated in the experiment that lasted for 4 h. All participants performed five tasks in each of the three speech conditions. Questionnaires were used to assess subjective perceptions of the speech conditions. Performance in the operation span task, the serial recall and the activation of prior knowledge from long-term memory were deteriorated in the speech condition with the highest speech intelligibility (STI = 0.65) in comparison with the other two conditions (STI = 0.10 and STI = 0.35). Unlike performance measures, questionnaire results showed consistent differences among all three speech conditions, i.e. subjective disturbance increased with ascending speech intelligibility. Thus, subjective comfort was disturbed more easily than performance. The results support the use of STI as an essential room acoustic design measure in open-plan offices. Reduction of speech intelligibility in office environments by proper acoustic design would be beneficial in terms of both work performance and subjective comfort. Proper acoustic design requires both the use of high acoustic absorption and an appropriate masking sound.

  17. Evaluation of Subjective and Objective Performance Metrics for Haptically Controlled Robotic Systems

    Directory of Open Access Journals (Sweden)

    Cong Dung Pham

    2014-07-01

    Full Text Available This paper studies in detail how different evaluation methods perform when it comes to describing the performance of haptically controlled mobile manipulators. Particularly, we investigate how well subjective metrics perform compared to objective metrics. To find the best metrics to describe the performance of a control scheme is challenging when human operators are involved; how the user perceives the performance of the controller does not necessarily correspond to the directly measurable metrics normally used in controller evaluation. It is therefore important to study whether there is any correspondence between how the user perceives the performance of a controller, and how it performs in terms of directly measurable metrics such as the time used to perform a task, number of errors, accuracy, and so on. To perform these tests we choose a system that consists of a mobile manipulator that is controlled by an operator through a haptic device. This is a good system for studying different performance metrics as the performance can be determined by subjective metrics based on feedback from the users, and also as objective and directly measurable metrics. The system consists of a robotic arm which provides for interaction and manipulation, which is mounted on a mobile base which extends the workspace of the arm. The operator thus needs to perform both interaction and locomotion using a single haptic device. While the position of the on-board camera is determined by the base motion, the principal control objective is the motion of the manipulator arm. This calls for intelligent control allocation between the base and the manipulator arm in order to obtain intuitive control of both the camera and the arm. We implement three different approaches to the control allocation problem, i.e., whether the vehicle or manipulator arm actuation is applied to generate the desired motion. The performance of the different control schemes is evaluated, and our

  18. Isometric hip and knee torque measurements as an outcome measure in robot assisted gait training.

    Science.gov (United States)

    Galen, Sujay S; Clarke, Celia J; McLean, Alan N; Allan, David B; Conway, Bernard A

    2014-01-01

    Strength changes in lower limb muscles following robot assisted gait training (RAGT) in subjects with incomplete spinal cord injury (ISCI) has not been quantified using objective outcome measures. To record changes in the force generating capacity of lower limb muscles (recorded as peak voluntary isometric torque at the knee and hip), before, during and after RAGT in both acute and subacute/chronic ISCI subjects using a repeated measures study design. Eighteen subjects with ISCI participated in this study (Age range: 26-63 years mean age = 49.3 ± 11 years). Each subject participated in the study for a total period of eight weeks, including 6 weeks of RAGT using the Lokomat system (Hocoma AG, Switzerland). Peak torques were recorded in hip flexors, extensors, knee flexors and extensors using torque sensors that are incorporated within the Lokomat. All the tested lower limb muscle groups showed statistically significant (p torques in the acute subjects. Comparison between the change in peak torque generated by a muscle and its motor score over time showed a non-linear relationship. The peak torque recorded during isometric contractions provided an objective outcome measure to record changes in muscle strength following RAGT.

  19. Modular Organization of Exploratory Force Development Under Isometric Conditions in the Human Arm.

    Science.gov (United States)

    Roh, Jinsook; Lee, Sang Wook; Wilger, Kevin D

    2018-01-31

    Muscle coordination of isometric force production can be explained by a smaller number of modules. Variability in force output, however, is higher during exploratory/transient force development phases than force maintenance phase, and it is not clear whether the same modular structure underlies both phases. In this study, eight neurologically-intact adults isometrically performed target force matches in 54 directions at hands, and electromyographic (EMG) data from eight muscles were parsed into four sequential phases. Despite the varying degree of motor complexity across phases (significant between-phase differences in EMG-force correlation, angular errors, and between-force correlations), the number/composition of motor modules were found equivalent across phases, suggesting that the CNS systematically modulated activation of the same set of motor modules throughout sequential force development.

  20. Music performance anxiety in skilled pianists: effects of social-evaluative performance situation on subjective, autonomic, and electromyographic reactions.

    Science.gov (United States)

    Yoshie, Michiko; Kudo, Kazutoshi; Murakoshi, Takayuki; Ohtsuki, Tatsuyuki

    2009-11-01

    Music performance anxiety (MPA), or stage fright in music performance, is a serious problem for many musicians, because performance impairment accompanied by MPA can threaten their career. The present study sought to clarify on how a social-evaluative performance situation affects subjective, autonomic, and motor stress responses in pianists. Measurements of subjective state anxiety, heart rate (HR), sweat rate (SR), and electromyographic (EMG) activity of upper extremity muscles were obtained while 18 skilled pianists performed a solo piano piece(s) of their choice under stressful (competition) and non-stressful (rehearsal) conditions. Participants reported greater anxiety in the competition condition, which confirmed the effectiveness of stress manipulation. The HR and SR considerably increased from the rehearsal to competition condition reflecting the activation of sympathetic division of the autonomic nervous system. Furthermore, participants showed higher levels of the EMG magnitude of proximal muscles (biceps brachii and upper trapezius) and the co-contraction of antagonistic muscles in the forearm (extensor digitorum communis and flexor digitorum superficialis) in the competition condition. Although these responses can be interpreted as integral components of an adaptive biological system that creates a state of motor readiness in an unstable or unpredictable environment, they can adversely influence pianists by disrupting their fine motor control on stage and by increasing the risk of playing-related musculoskeletal disorders.

  1. Effect of a Bluetooth-implemented hearing aid on speech recognition performance: subjective and objective measurement.

    Science.gov (United States)

    Kim, Min-Beom; Chung, Won-Ho; Choi, Jeesun; Hong, Sung Hwa; Cho, Yang-Sun; Park, Gyuseok; Lee, Sangmin

    2014-06-01

    The object was to evaluate speech perception improvement through Bluetooth-implemented hearing aids in hearing-impaired adults. Thirty subjects with bilateral symmetric moderate sensorineural hearing loss participated in this study. A Bluetooth-implemented hearing aid was fitted unilaterally in all study subjects. Objective speech recognition score and subjective satisfaction were measured with a Bluetooth-implemented hearing aid to replace the acoustic connection from either a cellular phone or a loudspeaker system. In each system, participants were assigned to 4 conditions: wireless speech signal transmission into hearing aid (wireless mode) in quiet or noisy environment and conventional speech signal transmission using external microphone of hearing aid (conventional mode) in quiet or noisy environment. Also, participants completed questionnaires to investigate subjective satisfaction. Both cellular phone and loudspeaker system situation, participants showed improvements in sentence and word recognition scores with wireless mode compared to conventional mode in both quiet and noise conditions (P Bluetooth-implemented hearing aids helped to improve subjective and objective speech recognition performances in quiet and noisy environments during the use of electronic audio devices.

  2. Reliability of isometric strength measurements in trunk and neck region: patients with chronic neck pain compared with pain-free persons.

    Science.gov (United States)

    Scheuer, Raphael; Friedrich, Martin

    2010-12-01

    Evaluation of reliability of isometric strength measurements in the neck and trunk region and comparison of these measurements between patients with chronic neck pain and pain-free subjects. Nonrandomized controlled trial. Institutional practice. Patients with neck pain (n=53) and pain-free persons (n=42) (mean age ± SD, 49.7±10.74 vs 48.7±12.02; women, 73% vs 71%). Strength of flexion, extension, and lateral flexion in the neck and trunk were measured. Each participant underwent 2 measurement passes on each of 2 examination days; 3 were performed by the same investigator, 1 by a second. Intrarater (short-term and long-term) and interrater reliability, differences in strength between both groups of probands. Reliability in both groups ranged from substantial to almost perfect (intraclass correlation coefficient: patients, .76-.89; control group, .80-.88). The patients' strength in the neck and trunk was significantly below that of the control group (P<.002). Isometric strength measurement is a reliable and feasible way to estimate the possible benefit of specific strengthening programs. Patients with chronic neck pain showed strength deficits in all measured regions. Copyright © 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  3. The efficacy of objective and subjective predictors of driving performance during sleep restriction and circadian misalignment.

    Science.gov (United States)

    Kosmadopoulos, Anastasi; Sargent, Charli; Zhou, Xuan; Darwent, David; Matthews, Raymond W; Dawson, Drew; Roach, Gregory D

    2017-02-01

    Fatigue is a significant contributor to motor-vehicle accidents and fatalities. Shift workers are particularly susceptible to fatigue-related risks as they are often sleep-restricted and required to commute around the clock. Simple assays of performance could provide useful indications of risk in fatigue management, but their effectiveness may be influenced by changes in their sensitivity to sleep loss across the day. The aim of this study was to evaluate the sensitivity of several neurobehavioral and subjective tasks to sleep restriction (SR) at different circadian phases and their efficacy as predictors of performance during a simulated driving task. Thirty-two volunteers (M±SD; 22.8±2.9 years) were time-isolated for 13-days and participated in one of two 14-h forced desynchrony protocols with sleep opportunities equivalent to 8h/24h (control) or 4h/24h (SR). At regular intervals during wake periods, participants completed a simulated driving task, several neurobehavioral tasks, including the psychomotor vigilance task (PVT), and subjective ratings, including a self-assessment measure of ability to perform. Scores transformed into standardized units relative to baseline were folded into circadian phase bins based on core body temperature. Sleep dose and circadian phase effect sizes were derived via mixed models analyses. Predictors of driving were identified with regressions. Performance was most sensitive to sleep restriction around the circadian nadir. The effects of sleep restriction around the circadian nadir were larger for simulated driving and neurobehavioral tasks than for subjective ratings. Tasks did not significantly predict driving performance during the control condition or around the acrophase during the SR condition. The PVT and self-assessed ability were the best predictors of simulated driving across circadian phases during SR. These results show that simple performance measures and self-monitoring explain a large proportion of the variance in

  4. Effect of tone-based sound stimulation on balance performance of normal subjects: preliminary investigation.

    Science.gov (United States)

    Pagnacco, Guido; Klotzek, Adam S; Carrick, Frederick R; Wright, Cameron H G; Oggero, Elena

    2015-01-01

    Sound is known to affect the human brain, hence sound or music therapy is sometimes used to improve a subject's physicaland mental health. In this study, the effects sound stimulation has on balance were investigated by means of computerizeddynamic posturography tests performed with eyes closed on an unstable surface using a CAPS® system, exceeding theInternational Society for Posture and Gait Research (ISPGR) recommended metrological performance standards. Subjectswere tested without listening to any music (baseline), listening to “pure music”, and listening to the same music with differenttones embedded into it (one for each key). We found that different subjects react differently to different tones. Music alonedid not have a statistically significant effect on balance compared to the baseline, but the “best” tone significantly improvedbalance compared to the baseline or the “pure music” conditions. Furthermore, the “worst” tone reduced the balancecompared to “pure music”, but the reduction was not statistically significant relative to the baseline. The results thereforeindicate that, at least relative to balance performance, the tone-based sound stimulation we investigated is effective andinherently safe, but that tone selection depends on the individual subject.

  5. Electromyographic examination of selected muscle activation during isometric core exercises.

    Science.gov (United States)

    Oliver, Gretchen D; Stone, Audrey J; Plummer, Hillary

    2010-11-01

    The purpose of the current study was to quantitatively examine the muscle activations of 3 common isometric core exercises (abdominal bridge, single-leg abdominal bridge, and superman) along with a newly introduced isometric exercise (flying squirrel) and determine if muscle activations differed among the exercises. The design was a comparison study. An athletic training classroom laboratory was where all data collections occurred. Thirty healthy collegiate graduate students (age, 23.4 ± 1.4 year; height, 171.3 ± 10.3 cm; mass, 73.3 ± 16.2 kg), regardless of sex, consented to participate. The independent variable was the muscle selected. The main outcome measures or dependent variables were the muscle activation reported as percent of maximum voluntary isometric contraction during each exercise. Results revealed that the multifidi produced the greatest muscle activity in all exercises, and the single-leg abdominal bridge exercise produced greater muscle activation than the general abdominal bridge exercise (P exercises may be a part of a core stability program. In addition, these findings may be incorporated into an isometric core exercise program to supplement a currently implemented isometric core exercise program.

  6. Effects of Background Music on Objective and Subjective Performance Measures in an Auditory BCI.

    Science.gov (United States)

    Zhou, Sijie; Allison, Brendan Z; Kübler, Andrea; Cichocki, Andrzej; Wang, Xingyu; Jin, Jing

    2016-01-01

    Several studies have explored brain computer interface (BCI) systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory, and other BCIs are typically studied without background music. Some work has explored the possibility of using polyphonic music in auditory BCI systems. However, this approach requires users with good musical skills, and has not been explored in online experiments. Our hypothesis was that an auditory BCI with background music would be preferred by subjects over a similar BCI without background music, without any difference in BCI performance. We introduce a simple paradigm (which does not require musical skill) using percussion instrument sound stimuli and background music, and evaluated it in both offline and online experiments. The result showed that subjects preferred the auditory BCI with background music. Different performance measures did not reveal any significant performance effect when comparing background music vs. no background. Since the addition of background music does not impair BCI performance but is preferred by users, auditory (and perhaps other) BCIs should consider including it. Our study also indicates that auditory BCIs can be effective even if the auditory channel is simultaneously otherwise engaged.

  7. Effects of background music on objective and subjective performance measures in an auditory BCI

    Directory of Open Access Journals (Sweden)

    Sijie Zhou

    2016-10-01

    Full Text Available Several studies have explored brain computer interface (BCI systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory and other BCIs are typically studied without background music. Some work has explored the possibility of using polyphonic music in auditory BCI systems. However, this approach requires users with good musical skills, and has not been explored in online experiments. Our hypothesis was that an auditory BCI with background music would be preferred by subjects over a similar BCI without background music, without any difference in BCI performance. We introduce a simple paradigm (which does not require musical skill using percussion instrument sound stimuli and background music, and evaluated it in both offline and online experiments. The result showed that subjects preferred the auditory BCI with background music. Different performance measures did not reveal any significant performance effect when comparing background music vs. no background. Since the addition of background music does not impair BCI performance but is preferred by users, auditory (and perhaps other BCIs should consider including it. Our study also indicates that auditory BCIs can be effective even if the auditory channel is simultaneously otherwise engaged.

  8. Relationships between Isometric Muscle Strength, Gait Parameters, and Gross Motor Function Measure in Patients with Cerebral Palsy.

    Science.gov (United States)

    Shin, Hyung Ik; Sung, Ki Hyuk; Chung, Chin Youb; Lee, Kyoung Min; Lee, Seung Yeol; Lee, In Hyeok; Park, Moon Seok

    2016-01-01

    This study investigated the correlation between isometric muscle strength, gross motor function, and gait parameters in patients with spastic cerebral palsy and to find which muscle groups play an important role for gait pattern in a flexed knee gait. Twenty-four ambulatory patients (mean age, 10.0 years) with spastic cerebral palsy who were scheduled for single event multilevel surgery, including distal hamstring lengthening, were included. Preoperatively, peak isometric muscle strength was measured for the hip flexor, hip extensor, knee flexor, and knee extensor muscle groups using a handheld dynamometer, and three-dimensional (3D) gait analysis and gross motor function measure (GMFM) scoring were also performed. Correlations between peak isometric strength and GMFM, gait kinematics, and gait kinetics were analyzed. Peak isometric muscle strength of all muscle groups was not related to the GMFM score and the gross motor function classification system level. Peak isometric strength of the hip extensor and knee extensor was significantly correlated with the mean pelvic tilt (r=-0.588, p=0.003 and r=-0.436, p=0.033) and maximum pelvic obliquity (r=-0.450, p=0.031 and r=-0.419, p=0.041). There were significant correlations between peak isometric strength of the knee extensor and peak knee extensor moment in early stance (r=0.467, p=0.021) and in terminal stance (r=0.416, p=0.043). There is no correlation between muscle strength and gross motor function. However, this study showed that muscle strength, especially of the extensor muscle group of the hip and knee joints, might play a critical role in gait by stabilizing pelvic motion and decreasing energy consumption in a flexed knee gait.

  9. Preserving Subject Variability in Group fMRI Analysis: Performance Evaluation of GICA versus IVA

    Directory of Open Access Journals (Sweden)

    Andrew eMichael

    2014-06-01

    Full Text Available Independent component analysis (ICA is a widely applied technique to derive functionally connected brain networks from fMRI data. Group ICA (GICA and Independent Vector Analysis (IVA are extensions of ICA that enable users to perform group fMRI analyses; however a full comparison of the performance limits of GICA and IVA has not been investigated. Recent interest in resting state fMRI data with potentially higher degree of subject variability makes the evaluation of the above techniques important. In this paper we compare component estimation accuracies of GICA and an improved version of IVA using simulated fMRI datasets. We systematically change the degree of component spatial variability and evaluate estimation accuracy over all spatial maps (SMs and time courses (TCs of the decomposition. Our results indicate the following: (1 at low levels of SM variability or when just one SM is varied, both GICA and IVA perform well, (2 at higher levels of SM variability or when more than one SMs are varied, IVA continues to perform well but GICA yields SM estimates that are composites of other SMs with errors in TCs, (3 both GICA and IVA remove spatial correlations of overlapping SMs and introduce artificial correlations in their TCs, (4 if number of SMs is over estimated, IVA continues to perform well but GICA introduces artifacts in the varying and extra SMs with artificial correlations in the TCs of extra components, and (5 in the absence or presence of SMs unique to one subject, GICA produces errors in TCs and IVA estimates are accurate. In summary, our simulation experiments (both simplistic and realistic and our holistic analyses approach indicate that IVA produces results that are closer to ground truth and thereby better preserves subject variability. The improved version of IVA is now packaged into the GIFT toolbox (http://mialab.mrn.org/software/gift.

  10. Correlation between architectural variables and torque in the erector spinae muscle during maximal isometric contraction.

    Science.gov (United States)

    Cuesta-Vargas, Antonio; González-Sánchez, Manuel

    2014-01-01

    This study analysed whether a significant relationship exists between the torque and muscle thickness and pennation angle of the erector spinae muscle during a maximal isometric lumbar extension with the lumbar spine in neutral position. This was a cross-sectional study in which 46 healthy adults performed three repetitions for 5 s of maximal isometric lumbar extension with rests of 90 s. During the lumbar extensions, bilateral ultrasound images of the erector spinae muscle (to measure pennation angle and muscle thickness) and torque were acquired. Reliability test analysis calculating the internal consistency (Cronbach's alpha) of the measure, correlation between pennation angle, muscle thickness and torque extensions were examined. Through a linear regression the contribution of each independent variable (muscle thickness and pennation angle) to the variation of the dependent variable (torque) was calculated. The results of the reliability test were: 0.976-0.979 (pennation angle), 0.980-0.980 (muscle thickness) and 0.994 (torque). The results show that pennation angle and muscle thickness were significantly related to each other with a range between 0.295 and 0.762. In addition, multiple regression analysis showed that the two variables considered in this study explained 68% of the variance in the torque. Pennation angle and muscle thickness have a moderate impact on the variance exerted on the torque during a maximal isometric lumbar extension with the lumbar spine in neutral position.

  11. Dystonic neck muscles show a shift in relative autospectral power during isometric contractions.

    Science.gov (United States)

    De Bruijn, E; Nijmeijer, S W R; Forbes, P A; Koelman, J H T M; Van Der Helm, F C T; Tijssen, M A J; Happee, R

    2017-10-01

    To identify effects of a deviant motor drive in the autospectral power of dystonic muscles during voluntary contraction in cervical dystonia patients. Submaximal (20%) isometric head-neck tasks were performed with the head fixed, measuring surface EMG of the sternocleidomastoid, splenius capitis and semispinalis capitis in CD patients and controls. Autospectral power of muscle activity, and head forces was analyzed using cumulative distribution functions (CDF). A downward shift between the theta/low alpha-band (3-10Hz) and the high alpha/beta-band (10-30Hz) was detected using the CDF10, defined as the cumulative power from 3 to 10Hz relative to power from 3 to 30Hz. CDF10 was increased in dystonic muscles compared to controls and patient muscles unaffected by dystonia, due to a 3-10Hz power increase and a 10-30Hz decrease. CDF10 also increased in patient head forces. Submaximal isometric contractions with the head fixed provided a well-defined test condition minimizing effects of reflexive feedback and tremor. We associate shifts in autospectral power with prokinetic sensorimotor control. Analysis of autospectral power in isometric tasks with the head fixed is a promising approach in research and diagnostics of cervical dystonia. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  12. Spectral properties of electromyographic and mechanomyographic signals during isometric ramp and step contractions in biceps brachii.

    Science.gov (United States)

    Qi, Liping; Wakeling, James M; Green, Adam; Lambrecht, Kirstin; Ferguson-Pell, Martin

    2011-02-01

    The purposes of this study were: (1) to apply wavelet and principal component analysis to quantify the spectral properties of the surface EMG and MMG signals from biceps brachii during isometric ramp and step muscle contractions when the motor units are recruited in an orderly manner, and (2) to compare the recruitment patterns of motor unit during isometric ramp and step muscle contractions. Twenty healthy participants (age = 34 ± 10.7 years) performed step and ramped isometric contractions. Surface EMG and MMG were recorded from biceps brachii. The EMGs and MMGs were decomposed into their intensities in time-frequency space using a wavelet technique. The EMG and MMG spectra were then compared using principal component analysis (PCA) and ANCOVA. Wavelet combined PCA offers a quantitative measure of the contribution of high and low frequency content within the EMG and MMG. The ANCOVA indicated that there was no significant difference in EMG total intensity, EMG(MPF), first and second principal component loading scores (PCI and PCII) between ramp and step contractions, whereas the MMG(MPF) and MMG PCI loading scores were significantly higher during ramp contractions than during step contractions. These findings suggested that EMG and MMG may offer complimentary information regarding the interactions between motor unit recruitment and firing rate that control muscle force production. In addition, our results support the hypothesis that different motor unit recruitment strategy was used by the muscle when contracting under different conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Isokinetic and isometric muscle strength combined with transcutaneous electrical muscle stimulation in primary fibromyalgia syndrome

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Wildschiødtz, Gordon; Danneskiold-Samsøe, B

    1991-01-01

    with superimposed transcutaneous electrical stimulation. The examination protocol was repeated after 1 h of resting. Isokinetic and isometric muscle strength was found to be, respectively, 45% (p = 0.0001) and 44% (p = 0.0001) lower in the patient group compared to the healthy subjects. The frequency...... of superimposed twitches was 65% in the patient group and 15% in the control group (p = 0.003). Patients with primary fibromyalgia have a lower maximum voluntary muscle strength than expected. The increased presence of superimposed electrically elicited twitches during maximum voluntary contraction indicates...

  14. Effect of oral dietary supplement for chicks subjected to thermal oscillation on performance and intestinal morphometry

    Directory of Open Access Journals (Sweden)

    Jovanir Inês Müller Fernandes

    2017-09-01

    Full Text Available The aim of the study was to evaluate the efficacy of a nutritional formulation based on amino acids and vitamins supplemented in the drinking water for chicks in the first week of life subjected to thermal oscillation on performance, organ development and intestinal morphometry from 1 to 21 days. 640-male broiler chicks were distributed in a 2x2 factorial completely randomized design (with or without dietary supplementation and at comfort temperature or thermal oscillation. Chicks subjected to thermal oscillation presented worse performance (p < 0.05 than those under thermal comfort of 1 to 7, 1 to 14 and 1 to 21 days. Nutritional supplementation did not alter the performance (p < 0.05 of the birds, but resulted in a higher body weight (p < 0.05 regardless of the environmental thermal condition. At 7 days, chicks under thermal comfort had better intestinal morphometric parameters (p < 0.05, in relation to birds under thermal oscillation. In conclusion, the temperature oscillations caused negative consequences to the productive performance and the intestinal morphology of chicks for which dietary supplementation was not enough to mitigate the effects of the environmental challenge during the first week of life of the birds.

  15. Tracking Systems for Virtual Rehabilitation: Objective Performance vs. Subjective Experience. A Practical Scenario

    Directory of Open Access Journals (Sweden)

    Roberto Lloréns

    2015-03-01

    Full Text Available Motion tracking systems are commonly used in virtual reality-based interventions to detect movements in the real world and transfer them to the virtual environment. There are different tracking solutions based on different physical principles, which mainly define their performance parameters. However, special requirements have to be considered for rehabilitation purposes. This paper studies and compares the accuracy and jitter of three tracking solutions (optical, electromagnetic, and skeleton tracking in a practical scenario and analyzes the subjective perceptions of 19 healthy subjects, 22 stroke survivors, and 14 physical therapists. The optical tracking system provided the best accuracy (1.074 ± 0.417 cm while the electromagnetic device provided the most inaccurate results (11.027 ± 2.364 cm. However, this tracking solution provided the best jitter values (0.324 ± 0.093 cm, in contrast to the skeleton tracking, which had the worst results (1.522 ± 0.858 cm. Healthy individuals and professionals preferred the skeleton tracking solution rather than the optical and electromagnetic solution (in that order. Individuals with stroke chose the optical solution over the other options. Our results show that subjective perceptions and preferences are far from being constant among different populations, thus suggesting that these considerations, together with the performance parameters, should be also taken into account when designing a rehabilitation system.

  16. Intra-Subject Variability of 5 Km Time Trial Performance Completed by Competitive Trained Runners

    Directory of Open Access Journals (Sweden)

    Fisher James

    2017-06-01

    Full Text Available Time-trials represent an ecologically valid approach to assessment of endurance performance. Such information is useful in the application of testing protocols and estimation of sample sizes required for research/magnitude based inference methods. The present study aimed to investigate the intra-subject variability of 5 km time-trial running performance in trained runners. Six competitive trained male runners (age = 33.8 ± 10.1 years; stature = 1.78 ± 0.01 m; body mass = 69.0 ± 10.4 kg, V. $\\it V^{.}$ O2max = 62.6 ± 11.0 ml·kg·min-1 completed an incremental exercise test to volitional exhaustion followed by 5 x 5 km time-trials (including a familiarisation trial, individually spaced by 48 hours. The time taken to complete each trial, heart rate, rating of perceived exertion and speed were all assessed. Intra-subject absolute standard error of measurement and the coefficient of variance were calculated for time-trial variables in addition to the intra-class correlation coefficient for time taken to complete the time-trial. For the primary measure time, results showed a coefficient of variation score across all participants of 1.5 ± 0.59% with an intra-class correlation coefficient score of 0.990. Heart rate, rating of perceived exertion and speed data showed a variance range between 0.8 and 3.05%. It was concluded that when compared with related research, there was observed low intra-subject variability in trained runners over a 5 km distance. This supports the use of this protocol for 5 km time-trial performance for assessment of nutritional strategies, ergogenic aids or training interventions on endurance running performance.

  17. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers

    Directory of Open Access Journals (Sweden)

    Makoto eBannai

    2012-04-01

    Full Text Available Approximately 30% of the general population suffers from insomnia. Given that insomnia causes many problems, amelioration of the symptoms is crucial. Recently, we found that a nonessential amino acid, glycine subjectively and objectively improves sleep quality in humans who have difficulty sleeping. We evaluated the effects of glycine on daytime sleepiness, fatigue and performances in sleep-restricted healthy subjects. Sleep was restricted to 25% less than the usual sleep time for three consecutive nights. Before bedtime, 3 g of glycine or placebo were ingested, sleepiness and fatigue were evaluated using the visual analogue scale (VAS and a questionnaire, and performance were estimated by personal computer (PC performance test program on the following day. In subjects given glycine, the VAS data showed a significant reduction in fatigue and a tendency toward reduced sleepiness. These observations were also found via the questionnaire, indicating that glycine improves daytime sleepiness and fatigue induced by acute sleep restriction. PC performance test revealed significant improvement in psychomotor vigilance test. We also measured plasma melatonin and the expression of circadian-modulated genes expression in the rat suprachiasmatic nucleus (SCN to evaluate the effects of glycine on circadian rhythms. Glycine did not show significant effects on plasma melatonin concentrations during either the dark or light period. Moreover, the expression levels of clock genes such as Bmal1 and Per2 remained unchanged. However, we observed a glycine-induced increase in the neuropeptides arginine vasopressin and vasoactive intestinal polypeptide in the light period. Although no alterations in the circadian clock itself were observed, our results indicate that glycine modulated SCN function. Thus, glycine modulates certain neuropeptides in the SCN and this phenomenon may indirectly contribute to improving the occasional sleepiness and fatigue induced by sleep

  18. Reliability and validity of videotaped functional performance tests in ACL-injured subjects

    DEFF Research Database (Denmark)

    von Porat, Anette; Holmström, Eva; Roos, Ewa

    2008-01-01

    during five functional tests in subjects with an anterior cruciate ligament (ACL) injury. METHOD: Twelve ACL-injured men, mean age 40 years, were video filmed before and after 12 weeks of knee-specific training when performing five different functional tests: walking, knee bending, step activity......, crossover hop on one leg and one-leg hop. The videos were observed by four physiotherapists, and the knee movement pattern quality, a feature of the loading strategy of the lower extremity, was scored on an 11-point rating scale. To assess the criterion validity, the observational rating was correlated...... validity found indicate that the knee movement pattern quality in ACL-injured subjects can be determined by visual observation of more demanding functional tests such as crossover hop on one leg and one-leg hop for distance....

  19. Pilot study of light therapy and neurocognitive performance of attention and memory in healthy subjects.

    Science.gov (United States)

    Bersani, Giuseppe; Marconi, Daniela; Limpido, Lucilla; Tarolla, Emanuele; Caroti, Eleonora

    2008-02-01

    The aim of this pilot study was to investigate whether light therapy improves healthy subjects' neurocognitive performance of attention, memory, and language. Ten subjects were treated with white bright light for 5 days and a control group of 10 with no treatment were assessed with a battery of neurocognitive tests which included the Stroop Colour Word Interference Test, the Verbal Fluency Test, the Story Recall Test, and the Word Pairs Recall Test. Analysis showed improvements in cognitive scores in both groups, although on all the cognitive tests the mean difference scores between baseline and endpoint were significantly larger in the light-treated group. These preliminary results suggest that short-term bright light may exert beneficial effects on cognitive functions.

  20. A Comparative Study of the Empirical Relationship in Student Performance between Physics and Other STEM Subjects

    Science.gov (United States)

    Guerra, Maricela

    The Next Generation Science Standards (NGSS) advocated by the National Research Council emphasize the connections among Science, Technology, Engineering, and Mathematics (STEM) disciplines. By design, NGSS is expected to replace the previous science education standards to enhance the quality of STEM education across the nation. To support this initiative, this investigation was conducted to fill a void in the research literature by developing an empirical indicator for the relationship of student performance across STEM subjects using a large-scale database from the Trends in Mathematics and Science Study (TIMSS). In particular, an innovative approach has been taken in this study to support the canonical correlation analysis of student plausible scores between physics and other STEM subjects at different grade levels and in a cross-country context. Results from this doctoral research revealed the need to strengthen the alignment between the intended, implemented, and attained curricula to support the integration of STEM disciplines in the United States.

  1. Viscoelastic Properties of Healthy Achilles Tendon are Independent of Isometric Plantar Flexion Strength and Cross-Sectional Area

    Science.gov (United States)

    Suydam, Stephen M.; Soulas, Elizabeth M.; Elliott, Dawn M.; Silbernagel, Karin Gravare; Buchanan, Thomas S.; Cortes, Daniel H.

    2015-01-01

    Changes in tendon viscoelastic properties are observed after injuries and during healing as a product of altered composition and structure. Continuous Shear Wave Elastography is a new technique measuring viscoelastic properties of soft tissues using external shear waves. Tendon has not been studied with this technique, therefore, the aims of this study were to establish the range of shear and viscosity moduli in healthy Achilles tendons, determine bilateral differences of these parameters and explore correlations of viscoelasticity to plantar flexion strength and tendon area. Continuous Shear Wave Elastography was performed over the free portion of both Achilles tendons from 29 subjects. Isometric plantar flexion strength and cross sectional area were measured. The average shear and viscous moduli was 83.2kPa and 141.0Pa-s, respectively. No correlations existed between the shear or viscous modulus and area or strength. This indicates that viscoelastic properties can be considered novel, independent biomarkers. The shear and viscosity moduli were bilaterally equivalent (p=0.013,0.017) which allows determining pathologies through side-to-side deviations. The average bilateral coefficient of variation was 7.2% and 9.4% for shear and viscosity modulus, respectively. The viscoelastic properties of the Achilles tendon may provide an unbiased, non-subjective rating system of tendon recovery and optimizing treatment strategies. PMID:25882209

  2. School-performance indicators and subjective health complaints: are there gender differences?

    Science.gov (United States)

    Brolin Låftman, Sara; Modin, Bitte

    2012-05-01

    Although boys and girls are generally located in the same physical school environment, it may be experienced differently by, and have varying implications for, boys and girls. Girls like school more and achieve higher school marks, but they also perceive more school-related pressure. Based on a total sample of 8456 ninth grade pupils in Stockholm in 2004, this study uses multilevel linear regression to analyse differences between boys and girls with regard to a number of school-performance indicators (demands, motivation, teacher support and school marks) and their association with subjective health complaints. Results showed that girls perceive more demands, show greater academic motivation, perform better in school and report more emotional support from teachers than boys. In contrast, instrumental and appraisal support from teachers are more commonly reported by boys. Associations between school-performance indicators and subjective health complaints were slightly stronger for girls than for boys. Contextual variation in health complaints, especially between classes, was found only for girls. High achievement motivation and emotional teacher support in the school class was associated with better pupil health, suggesting that a positive climate in terms of motivation and support favours class health as a whole. © 2011 The Authors. Sociology of Health & Illness © 2011 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

  3. Performance Testing of Lidar Components Subjected to Space Exposure in Space via MISSE 7 Mission

    Science.gov (United States)

    Prasad, Narasimha S.

    2012-01-01

    .The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 module was brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in space environment for more than one and a half year included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the current progress on post-flight performance testing of a high-speed photodetector and a balanced receiver is discussed. Preliminary findings show that detector characteristics did not undergo any significant degradation.

  4. Effects of habitual variations in napping on psychomotor performance, memory and subjective states.

    Science.gov (United States)

    Taub, J M

    1979-01-01

    Effects of habitual variations in napping on psychomotor performance, short-term memory and subjective states were investigated. The subjects were 32 healthy male university students who napped twice or more weekly in themorning and at night. Sixteen were randomly assigned to a control group and 16 to a nap(treatment) group. The experiment comprised two conditions of electrographically (EEG) recorded sleep for the nap group and two EEG monitored conditions of wakefulness for the controls. These conditions were scheduled from 9:35 to 11:35 a.m. and 12 hr later between 9:35 p.m. and 11:35 p.m. Measurements were obtained from: (a) a continuous 10-min auditory reaction time task, (b) a free recall task of short-term memory, (c) an activation-mood adjective check list, and (d) the Stanford Sleepiness scale. Except for memory the dependent variables of waking function were assessed 20 min before and 20 min after all conditions. Following each sleep condition the nap group as opposed to the controls showed a statistically significant improvement in reaction time performance, higher short-term retention, less reported sleepiness and elevated subjective states reflected by fice factors on the adjective mood-activation check list. Among the correlations computed the largest significant coefficients were of stage 4 and REM with posttreatment Stanford Sleepiness ratings. After naps, increased postdormital sleepiness was correlated with stage 4 and decreased sleepiness with REM sleep. Although few strikingly divergent functional effects were associated with morning and nocturanal naps, these did covary with sleep psychophysiology. It is postulated that the phase, the EEG-sleep stages and possibly the duration of accustomed naps are less salient factors influencing performance when the time since awakening until behavioral assessment can be kept constant.

  5. EFFECT OF ISOMETRIC QUADRICEPS STRENGTHENING EXERCISE AT MULTIPLE ANGLES IN KNEE JOINT AMONG NORMAL ADULTS

    Directory of Open Access Journals (Sweden)

    JibiPaul

    2014-04-01

    Full Text Available Introduction: Strengthening exercises have been routinely used in persons with orthopaedic problems and athletes to increase force production or minimize muscle imbalance and joint injuries.Many studies have reported that isometric contractions can rapidly increases strength in quadriceps muscle. Objective: Objective of the study was to find out the effect of isometric strengthening exercise on strength of quadriceps at 45 and 90 degree of knee joint and also to compare the effect of strengthening exercise on strength of quadriceps at multiple angles of knee joint among control and experimental group. Methodology: This was a ccomparative experimental study with forty female healthy subjects from physiotherapy department of KPJ Healthcare University College, Malaysia. Convenient sampling method used to select the samples. The subjects were selected by inclusion criteria and randomly divided equally in to two with 20 subjects in each group. Isometric strengthening exercise and squatting exercise were given as intervention program for eight weeks respectively for experimental and control group. Pre and post data of quadriceps muscle strength measured were collected separately at 45 and 90 degree of knee joint using goniometry during resisted extension of knee in multi gym. Result: In experimental group Pre –Post statistical analysis found significant effect in increase of quadriceps strength at 45 and 90 degree with P<0.0001.****In control group quadriceps pre-post statistical analysis found no significant effect in increase of quadriceps strength at 45 and 90 degree with P<0.083NS and P<0.055 NS respectively. Comparative study between experimental and control groups for quadriceps strength at 90 degree of knee joint found significant effect in increase of quadriceps strength with P< 0.001.*** Comparative study between experimental and control groups for quadriceps strength at 45 degree of knee joint found significant effect in increase of

  6. Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Marchetti

    2016-01-01

    Full Text Available The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20°, 90°, and 140° in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL, vastus medialis (VM, rectus femoris (RF, biceps femoris (BF, semitendinosus (ST, and gluteus maximus (GM. In general, muscle activity was the highest at 90° for the three quadriceps muscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20° and 90° compared to 140°. The BF and ST displayed similar activation at all joint angles. In conclusion, knee position alters muscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90° generates the highest overall muscle activation, yet an isometric back squat at 140° generates the lowest overall muscle activation of the VL and GM only.

  7. Subjective experiences of occupational performance of activities of daily living in patients with mild stroke

    DEFF Research Database (Denmark)

    Kristensen, Hanne Kaae; Postat, Annemette; Poulsen, Trine

    2014-01-01

    and risk of accidents. Conclusion: It is important to view the patients with mild stroke as heterogeneous, and consider post-stroke fatigue and emotional reactions when evaluating rehabilitation needs. Therefore, it is important to look further into structured tools, which examine how well the participant......Aim: To investigate the subjective experiences of occupational performance of activities of daily living (ADL) in patients with mild stroke. Methodology: Data was generated from January – December 2011 and consisted of 41 individual ADL-I interviews with patients in hospital and another 41...

  8. Effect of Acute Effort on Isometric Strength and Body Balance: Trained vs. Untrained Paradigm.

    Science.gov (United States)

    Sterkowicz, Stanisław; Jaworski, Janusz; Lech, Grzegorz; Pałka, Tomasz; Sterkowicz-Przybycień, Katarzyna; Bujas, Przemysław; Pięta, Paweł; Mościński, Zenon

    2016-01-01

    Years of training in competitive sports leads to human body adaptation to a specific type of exercise. In judo bouts, maintaining hand grip on an opponent's clothes and postural balance is essential for the effective technical and tactical actions. This study compares changes after maximal anaerobic exercise among judo athletes and untrained subjects regarding 1) maximum isometric handgrip strength (HGSmax) and accuracy at the perceived 50% maximum handgrip force (1/2HGSmax) and 2) the balance of 13 judo athletes at national (n = 8) and international (n = 5) competitive levels and 19 untrained university students. The groups did not differ in age, body height, and weight. Body mass index (BMI) and body composition (JAWON) were evaluated. The Wingate Anaerobic Test (WAnT, Monark 875E) measured recommended anaerobic capacity indices. Hand grip strength (Takei dynamometer) and balance (biplate balance platform) were measured before warm-up (T1), before the WAnT test (T2), and after (T3). Parametric or non-parametric tests were performed after verifying the variable distribution assumption. Judoists had higher BMI and fat-free mass index (FFMI) than the students. The athletes also showed higher relative total work and relative peak power and lower levels of lactic acid. The difference in judoists between HGSmax at T1 and HGSmax at T3 was statistically significant. Before warm-up (T1), athletes showed higher strength (more divergent from the calculated ½HGSmax value) compared to students. Substantial fatigue after the WAnT test significantly deteriorated the body stability indices, which were significantly better in judo athletes at all time points. The findings suggest specific body adaptations in judoists, especially for body composition, anaerobic energy system efficiency, and postural balance. These characteristics could be trained for specifically by judo athletes to meet the time-motion and anaerobic demands of contemporary bouts.

  9. Real-time muscle state estimation from EMG signals during isometric contractions using Kalman filters.

    Science.gov (United States)

    Menegaldo, Luciano L

    2017-12-01

    State-space control of myoelectric devices and real-time visualization of muscle forces in virtual rehabilitation require measuring or estimating muscle dynamic states: neuromuscular activation, tendon force and muscle length. This paper investigates whether regular (KF) and extended Kalman filters (eKF), derived directly from Hill-type muscle mechanics equations, can be used as real-time muscle state estimators for isometric contractions using raw electromyography signals (EMG) as the only available measurement. The estimators' amplitude error, computational cost, filtering lags and smoothness are compared with usual EMG-driven analysis, performed offline, by integrating the nonlinear Hill-type muscle model differential equations (offline simulations-OS). EMG activity of the three triceps surae components (soleus, gastrocnemius medialis and gastrocnemius lateralis), in three torque levels, was collected for ten subjects. The actualization interval (AI) between two updates of the KF and eKF was also varied. The results show that computational costs are significantly reduced (70x for KF and 17[Formula: see text] for eKF). The filtering lags presented sharp linear relationships with the AI (0-300 ms), depending on the state and activation level. Under maximum excitation, amplitude errors varied in the range 10-24% for activation, 5-8% for tendon force and 1.4-1.8% for muscle length, reducing linearly with the excitation level. Smoothness, measured by the ratio between the average standard variations of KF/eKF and OS estimations, was greatly reduced for activation but converged exponentially to 1 for the other states by increasing AI. Compared to regular KF, extended KF does not seem to improve estimation accuracy significantly. Depending on the particular application requirements, the most appropriate KF actualization interval can be selected.

  10. Effect of Acute Effort on Isometric Strength and Body Balance: Trained vs. Untrained Paradigm.

    Directory of Open Access Journals (Sweden)

    Stanisław Sterkowicz

    Full Text Available Years of training in competitive sports leads to human body adaptation to a specific type of exercise. In judo bouts, maintaining hand grip on an opponent's clothes and postural balance is essential for the effective technical and tactical actions. This study compares changes after maximal anaerobic exercise among judo athletes and untrained subjects regarding 1 maximum isometric handgrip strength (HGSmax and accuracy at the perceived 50% maximum handgrip force (1/2HGSmax and 2 the balance of 13 judo athletes at national (n = 8 and international (n = 5 competitive levels and 19 untrained university students. The groups did not differ in age, body height, and weight. Body mass index (BMI and body composition (JAWON were evaluated. The Wingate Anaerobic Test (WAnT, Monark 875E measured recommended anaerobic capacity indices. Hand grip strength (Takei dynamometer and balance (biplate balance platform were measured before warm-up (T1, before the WAnT test (T2, and after (T3. Parametric or non-parametric tests were performed after verifying the variable distribution assumption. Judoists had higher BMI and fat-free mass index (FFMI than the students. The athletes also showed higher relative total work and relative peak power and lower levels of lactic acid. The difference in judoists between HGSmax at T1 and HGSmax at T3 was statistically significant. Before warm-up (T1, athletes showed higher strength (more divergent from the calculated ½HGSmax value compared to students. Substantial fatigue after the WAnT test significantly deteriorated the body stability indices, which were significantly better in judo athletes at all time points. The findings suggest specific body adaptations in judoists, especially for body composition, anaerobic energy system efficiency, and postural balance. These characteristics could be trained for specifically by judo athletes to meet the time-motion and anaerobic demands of contemporary bouts.

  11. Transfer of dynamic motor skills acquired during isometric training to free motion.

    Science.gov (United States)

    Melendez-Calderon, Alejandro; Tan, Michael; Bittmann, Moria Fisher; Burdet, Etienne; Patton, James L

    2017-07-01

    Recent studies have explored the prospects of learning to move without moving, by displaying virtual arm movement related to exerted force. However, it has yet to be tested whether learning the dynamics of moving can transfer to the corresponding movement. Here we present a series of experiments that investigate this isometric training paradigm. Subjects were asked to hold a handle and generate forces as their arms were constrained to a static position. A precise simulation of reaching was used to make a graphic rendering of an arm moving realistically in response to the measured interaction forces and simulated environmental forces. Such graphic rendering was displayed on a horizontal display that blocked their view to their actual (statically constrained) arm and encouraged them to believe they were moving. We studied adaptation of horizontal, planar, goal-directed arm movements in a velocity-dependent force field. Our results show that individuals can learn to compensate for such a force field in a virtual environment and transfer their new skills to the actual free motion condition, with performance comparable to practice while moving. Such nonmoving techniques should impact various training conditions when moving may not be possible.NEW & NOTEWORTHY This study provided early evidence supporting that training movement skills without moving is possible. In contrast to previous studies, our study involves 1) exploiting cross-modal sensory interactions between vision and proprioception in a motionless setting to teach motor skills that could be transferable to a corresponding physical task, and 2) evaluates the movement skill of controlling muscle-generated forces to execute arm movements in the presence of external forces that were only virtually present during training. Copyright © 2017 the American Physiological Society.

  12. Regular physical exercise improves cardiac autonomic and muscle vasodilatory responses to isometric exercise in healthy elderly

    Directory of Open Access Journals (Sweden)

    Sarmento AO

    2017-06-01

    sympathetic activity compared to physically active older adult subjects at baseline (63.13±3.31 vs 50.45±3.55 nu, P=0.02. The variance (heart rate variability index was increased in active older adults (1,438.64±448.90 vs 1,402.92±385.14 ms, P=0.02, and cardiac sympathetic activity (symbolic analysis was increased in sedentary older adults (5,660.91±1,626.72 vs 4,381.35±1,852.87, P=0.03 during isometric handgrip exercise. Sedentary older adults showed higher cardiac sympathetic activity (spectral analysis (71.29±4.40 vs 58.30±3.50 nu, P=0.03 and lower parasympathetic modulation (28.79±4.37 vs 41.77±3.47 nu, P=0.03 compared to physically active older adult subjects during isometric handgrip exercise. Regarding muscle vasodilation response, there was an increase in the skeletal muscle blood flow in the second (4.1±0.5 vs 3.7±0.4 mL/min per 100 mL, P=0.01 and third minute (4.4±0.4 vs 3.9±0.3 mL/min per 100 mL, P=0.03 of handgrip exercise in active older adults. The results indicate that regular physical activity improves neurovascular control of muscle blood flow and cardiac autonomic response during isometric handgrip exercise in healthy older adult subjects. Keywords: forearm blood flow, handgrip exercise, heart rate variability, sympathetic, parasympathetic, aging

  13. Effects of Sleep Hygiene Education on Subjective Sleep Quality and Academic Performance

    Directory of Open Access Journals (Sweden)

    Erkan Sahin

    2014-12-01

    Full Text Available Aim: Sleep problems are common in students with one third of university students reporting insufficient sleep. It is known that sleep quality and daytime sleepiness cause decrasing academic performans. For this reason we aimed to investigate the effects of a sleep hygiene education on sleep quality and academic performance of first year medical students. Material and Method: Self-reported sleep data and academic performance of 131 first grade medical students were collected. To all students enrolled Pittsburg Sleep Quality Scale in the assessment of sleep quality and Epworth Sleepiness Scale for assessment of daytime sleepiness in the evaluation.The students were divided into two subgroups and the intervention group received a 30 minute structured sleep hygiene education. Global academic performance was assessed by grade point average at the end of the year. Results: Mean Pittsburgh sleep quality index score of the students was 7.9±3.5 and 106 (82.8% of then had a score %u22655.After intervention, .the worse the initial sleep quality, the more improvement by the sleep hygiene education on sleep quality and academic performance. Discussion: An education on sleep hygiene might improve subjective sleep quality and academic performance of medical students.

  14. Alternative computer mouse designs: performance, posture, and subjective evaluations for college students aged 18-25.

    Science.gov (United States)

    Feathers, David J; Rollings, Kimberly; Hedge, Alan

    2013-01-01

    Students are faced with work demands requiring intense computer use throughout the week, often with cumulative hourly use per day exceeding that of adult workers. Extended daily computer use has been associated with a reported increase of musculoskeletal symptoms for college-aged students. New mouse designs offer alternative movement and postural strategies to potentially mitigate musculoskeletal stress for students. This study investigates the use of alternative computer mouse designs by college-aged students (18-25) through a precision task (point-and-click an on-screen target). Wrist movements, hand posture, and associated subjective user data were collected across innovative mouse designs to understand the physical impact and basic usability issues for this population. Twenty-one (21) healthy, right handed students (11 female; 10 male) were enrolled in this study. Five mouse designs were assessed by investigating hand fit, wrist movements, and subjective accounts of ease of use, perceived control, comfort and aesthetics. Human performance was captured for each mouse design in terms of peak velocity, average movement time, and fastest movement direction using an electrogoniometer as participants performed the ISO 9241 multipoint standard Fitts' task using the Generalized Fitts' Law Model Builder software (GFLMB v.1.1C; [1]) within a zero-error setting (point-and-click task). Hand measurements were taken in both standardized anthropometric positions and adapted hand positions on five alternative mouse designs for a total of seven sets of measurements for each participant. Subjective data was collected through a series of questionnaires that were administered before, during, and after the mouse tasks. Results for human performance, distal upper extremity posture (hand/wrist), and subjective data such as overall preference, ease of use, perceived control, and comfort are given for this population. Wrist extension exceeded 30 degrees for over 50% of the total

  15. Objective and subjective visual performance of multifocal contact lenses: pilot study.

    Science.gov (United States)

    Vasudevan, Balamurali; Flores, Michael; Gaib, Sara

    2014-06-01

    The aim of the present study was to compare the objective and subjective visual performance of three different soft multifocal contact lenses. 10 subjects (habitual soft contact lens wearers) between the ages of 40 and 45 years participated in the study. Three different multifocal silicone hydrogel contact lenses (Acuvue Oasys, Air Optix and Biofinity) were fit within the same visit. All the lenses were fit according to the manufacturers' recommendation using the respective fitting guide. Visual performance tests included low and high contrast distance and near visual acuity, contrast sensitivity, range of clear vision and through-focus curve. Objective visual performance tests included measurement of open field accommodative response at different defocus levels and optical aberrations at different viewing distances. Accommodative response was not significantly different between the three types of multifocal contact lenses at each of the accommodative stimulus levels (p>0.05). Accommodative lag increased for higher stimulus levels for all 3 types of contact lenses. Ocular aberrations were not significantly different between these 3 contact lens designs at each of the different viewing distances (p>0.05). In addition, optical aberrations did not significantly differ between different viewing distances for any of these lenses (p>0.05). ANOVA revealed no significant difference in high and low contrast distance visual acuity as well as near visual acuity and contrast sensitivity function between the 3 multifocal contact lenses and spectacles (p>0.05). There was no statistically significant difference in accommodative response, optical aberrations or visual performance between the 3 multifocal contact lenses in early presbyopes. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  16. Effects of Isometric Scaling on Vertical Jumping Performance

    NARCIS (Netherlands)

    Bobbert, M.F.

    2013-01-01

    Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli's law, which states that jump height does

  17. Isometric handgrip does not elicit cardiovascular overload or post-exercise hypotension in hypertensive older women

    Directory of Open Access Journals (Sweden)

    Olher RR

    2013-06-01

    Full Text Available Rafael dos Reis Vieira Olher,1,2,* Danilo Sales Bocalini,3,* Reury Frank Bacurau,4 Daniel Rodriguez,5 Aylton Figueira Jr,5 Francisco Luciano Pontes Jr,4 Francisco Navarro,6 Herbert Gustavo Simões,1 Ronaldo Carvalho Araujo,7 Milton Rocha Moraes8 1Universidade Católica de Brasília, Distrito Federal, 2Universidade Gama Filho, Rio de Janeiro, 3Universidade Nove de Julho (UNINOVE, São Paulo, 4Universidade de São Paulo – Escola de Artes, Ciências e Humanidades, São Paulo, 5Universidade São Judas Tadeu (USJT, São Paulo, Brazil, 6Universidade Federal do Maranhão, Maranhão, 7Universidade de São Paulo, Instituto de Ciências Biomédicas, São Paulo, 8Universidade Federal de São Paulo – Escola Paulista de Medicina, São Paulo, Brazil *These authors contributed equally to this work Background: Arterial hypertension is a serious health problem affecting mainly the elderly population. Recent studies have considered both aerobic and resistance exercises as a non-pharmacological aid for arterial hypertension treatment. However, the cardiovascular responses of the elderly to isometric resistance exercise (eg, isometric handgrip [IHG] have not yet been documented. Objective: The purpose of this study was to investigate cardiovascular responses to different intensities of isometric exercise, as well as the occurrence of post-isometric exercise hypotension in hypertensive elderly people under antihypertensive medication treatment. Patients and methods: Twelve women volunteered to participate in the study after a maximal voluntary contraction test (MVC and standardization of the intervention workload consisting of two sessions of IHG exercise performed in four sets of five contractions of a 10-second duration. Sessions were performed both at 30% of the MVC and 50% of the MVC, using a unilateral IHG protocol. Both intensities were compared with a control session without exercise. Systolic blood pressure (SBP and diastolic blood pressure (DBP at rest

  18. Performance of Purunã beef calves subjected to different weaning systems

    Directory of Open Access Journals (Sweden)

    Fernando Kuss

    2014-09-01

    Full Text Available The study was developed at Fazenda Modelo an Experimental Station belonged to the Instituto Agronômico do Paraná - IAPAR, in the city of Ponta Grossa, PR, from June to November 2011. The objective was to evaluate the performance of calves subjected to different weaning systems. 161 calves crossbred Purunã were divided into three groups: calves subjected to early weaning (DP, weaned at an average of 75 days old; calves subjected to controlled nursing system (AC with 75 days of age, exposed to suck only once a day during the duration of the breeding season (85 days and; the control group, calves submitted to the system of conventional weaning (DC, were kept together with cow, without interfering in breastfeeding until the end of the breeding season (85 days. Calves fed the DP had lower mean (P<0.05 average daily gain (0.56 kg during the experimental group compared to the AC and DC (0.95 kg and 0.88 kg, respectively which did not differ (P<0.05. Thus, the DP had calves at the end of the breeding season, 32.36 kg and 26.48 kg unless the AC group (167.44 kg and DC (161.56 kg, respectively. The system controlled breastfeeding does not provid damage on the performance of calves at 150 days of age. Already early weaning at 75 days cause decrease of 19.6% in weight of calves at 150 days of age compared to suckler calves.

  19. Effects of Visual Communication Tool and Separable Status Display on Team Performance and Subjective Workload in Air Battle Management

    National Research Council Canada - National Science Library

    Schwartz, Daniel; Knott, Benjamin A; Galster, Scott M

    2008-01-01

    ... ambient cabin noise while performing several visual and manual tasks. The purpose of this study is to compare team performance and subjective workload on a simulated AWACS scenario, for two conditions of communication...

  20. A modified isometric test to evaluate blood pressure control with ...

    African Journals Online (AJOL)

    Blood pressure at rest is not predictive of roundthe- clock values. Blood pressure should therefore be measured during effort to evaluate hypertension and its response to treatment. The effect of sustained-release verapamil (240 mg taken once a day) on blood pressure at rest and during isometric effort was therefore ...

  1. Probing disorder in isometric pyrochlore and related complex oxides.

    Science.gov (United States)

    Shamblin, Jacob; Feygenson, Mikhail; Neuefeind, Joerg; Tracy, Cameron L; Zhang, Fuxiang; Finkeldei, Sarah; Bosbach, Dirk; Zhou, Haidong; Ewing, Rodney C; Lang, Maik

    2016-05-01

    There has been an increased focus on understanding the energetics of structures with unconventional ordering (for example, correlated disorder that is heterogeneous across different length scales). In particular, compounds with the isometric pyrochlore structure, A2B2O7, can adopt a disordered, isometric fluorite-type structure, (A, B)4O7, under extreme conditions. Despite the importance of the disordering process there exists only a limited understanding of the role of local ordering on the energy landscape. We have used neutron total scattering to show that disordered fluorite (induced intrinsically by composition/stoichiometry or at far-from-equilibrium conditions produced by high-energy radiation) consists of a local orthorhombic structural unit that is repeated by a pseudo-translational symmetry, such that orthorhombic and isometric arrays coexist at different length scales. We also show that inversion in isometric spinel occurs by a similar process. This insight provides a new basis for understanding order-to-disorder transformations important for applications such as plutonium immobilization, fast ion conduction, and thermal barrier coatings.

  2. Differential contributions of ankle plantarflexors during submaximal isometric muscle action

    DEFF Research Database (Denmark)

    Masood, Tahir; Bojsen-Møller, Jens; Kalliokoski, Kari K

    2014-01-01

    The objective of this study was to investigate the relative contributions of superficial and deep ankle plantarflexors during repetitive submaximal isometric contractions using surface electromyography (SEMG) and positron emission tomography (PET). Myoelectric signals were obtained from twelve....... The findings of this study provide valuable reference for studies where individual muscle contributions are estimated using models and simulations....

  3. Cylindrical symmetry locally isometric $AdS_{4}$ spacetime

    CERN Document Server

    Ahmed, Faizuddin; Sarma, Debojit; Myrzakulov, Ratbay

    2016-01-01

    We present a maximally symmetric vacuum spacetime, which is locally isometric anti- de Sitter, admitting closed timelike curves appear after a definite instant of time i.e., a time-machine spacetime. The spacetime is regular, free-from curvature singularities and an $4D$ extension of the Misner space in curved spacetime with identical causality violating properties.

  4. Isometric coactions of compact quantum groups on compact ...

    Indian Academy of Sciences (India)

    isometry group' in Rieffel's framework, we might expect it to be compact. Therefore, we gather some information on compact quantum groups and compact quantum metric spaces together with other preliminary notions in the second section. Next, we introduce our notion of isometric coactions in the third section. We show in ...

  5. Isometric coactions of compact quantum groups on compact ...

    Indian Academy of Sciences (India)

    We propose a notion of isometric coaction of a compact quantum group on a compact quantum metric space in the framework of Rieffel, where the metric structure is given by a Lipnorm. Within this setting we study the problem of the existence of a quantum isometry group.

  6. A modified isometric test to evaluate blood pressure control with ...

    African Journals Online (AJOL)

    SAMJ. VOL 83. NOV 1993. A modified isometric test to evaluate blood pressure control with once-daily slow-release verapamil. A. CANTOR, H. GILUTZ, T. MEYER. Abstract Blood pressure at rest is not predictive of round- the-clock values. Blood pressure should therefore be measured during effort to evaluate hypertension.

  7. Using subjective judgement to determine the validity of a tutorial performance evaluation instrument

    Directory of Open Access Journals (Sweden)

    Melanie L. Lack

    2009-04-01

    Full Text Available

    Evaluating students’ learning performance is dependent on assessment criteria from which valid inferences can be made about student learning. An existing 36-item instrument used to evaluate baccalaureate nursing students’ performance in problem-based learning tutorials was presented to experts in nursing for their subjective judgement of item validity. Quantitative analysis of data sets from experts’ judgements was used to construct a valid measurement scale for evaluating students’ tutorial performance. The objectives of the study were to determine the content validity of items in a tutorial performance evaluation (TPE instrument and to determine the construct validity of items through paired comparison of main and sub-items in the instrument. Academic experts (n = 8 from two South African universities were selected by means of purposive, maximum variation sampling. Data were collected in three rounds of the Delphi technique, which incorporated the Subjective Judgement Model for paired comparison of instrument items. Experts’ ratings were captured on a visual analogue scale for each item. Relative item weights were determined using
    paired comparisons. Statistical analysis resulted in ratio scale data, each item being assigned a ratio relative to its weight. It was concluded that quantitative analysis of subjective judgements is useful to determine the construct validity of items through paired comparison of items in a TPE instrument. This article presents the methodological perspectives of subjective judgement to establish instrument validity.

    Opsomming

    Die evaluering van studente se leervermoë is afhanklik van die waardebepalingskriteria waarvan geldige afleidings betreffende die student se leerervaring gemaak kan word. ’n Bestaande instrument met 36 items waarmee baccalaureus-verpleegkundestudente se prestasie in die probleemgebaseerde leertutoriale geëvalueer is, is aan kundiges in

  8. 40 CFR 80.820 - What gasoline is subject to the toxics performance requirements of this subpart?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false What gasoline is subject to the toxics... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Toxics Gasoline Toxics Performance Requirements § 80.820 What gasoline is subject to the toxics performance...

  9. Validity and reliability of a low-cost digital dynamometer for measuring isometric strength of lower limb.

    Science.gov (United States)

    Romero-Franco, Natalia; Jiménez-Reyes, Pedro; Montaño-Munuera, Juan A

    2017-11-01

    Lower limb isometric strength is a key parameter to monitor the training process or recognise muscle weakness and injury risk. However, valid and reliable methods to evaluate it often require high-cost tools. The aim of this study was to analyse the concurrent validity and reliability of a low-cost digital dynamometer for measuring isometric strength in lower limb. Eleven physically active and healthy participants performed maximal isometric strength for: flexion and extension of ankle, flexion and extension of knee, flexion, extension, adduction, abduction, internal and external rotation of hip. Data obtained by the digital dynamometer were compared with the isokinetic dynamometer to examine its concurrent validity. Data obtained by the digital dynamometer from 2 different evaluators and 2 different sessions were compared to examine its inter-rater and intra-rater reliability. Intra-class correlation (ICC) for validity was excellent in every movement (ICC > 0.9). Intra and inter-tester reliability was excellent for all the movements assessed (ICC > 0.75). The low-cost digital dynamometer demonstrated strong concurrent validity and excellent intra and inter-tester reliability for assessing isometric strength in the main lower limb movements.

  10. Comparison of the Effect of Massage Therapy and Isometric Exercises on Primary Dysmenorrhea: A Randomized Controlled Clinical Trial.

    Science.gov (United States)

    Azima, Sara; Bakhshayesh, Hajar Rajaei; Kaviani, Maasumeh; Abbasnia, Keramatallah; Sayadi, Mehrab

    2015-12-01

    Dysmenorrhea is the most common cyclic pelvic pain, and it affects the quality of life of many women. We sought to compare the effects of massage and isometric exercises on primary dysmenorrhea. We conducted a randomized controlled trial at the dormitories of Shiraz University among 102 students with primary dysmenorrheal. The student groups were randomly divided into massage, isometric exercises, and control groups. The first group received 2 consecutive cycles of effleurage massage with lavender oil. The second group had 8 weeks of isometric exercises. No intervention was performed for the control group. Pain intensity was measured and recorded by using a visual analog scale. In addition, the duration of pain was measured in hours, and Spielberger's questionnaire was used to measure the anxiety level. Pain intensity had significantly reduced in the massage and exercises groups; the reduction was more significant in the massage group (P massage group after the third cycle (P = .017). Based on the present findings, it seems that massage therapy and isometric exercises were effective in reducing some symptoms of dysmenorrhea. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

  11. Subjective recovery time after exhausting muscular activity in postpolio and control subjects.

    Science.gov (United States)

    Agre, J C; Rodriquez, A A; Franke, T M

    1998-01-01

    The purpose of this study was to determine whether the time to subjectively fully recover after the performance of exhausting muscular exercise was greater in unstable postpolio as compared with stable postpolio or control subjects. Twenty-five unstable (those complaining of declining muscle strength) postpolio, 16 stable (those denying declining muscle strength) postpolio, and 25 control subjects performed an isometric contraction of the knee extensor (quadriceps femoris) musculature at 40% of maximal torque until they were no longer able to do so. Five-second maximal effort contractions were made every 30 s through 2 min after the time of failure was reached and then at 1-min intervals through 10 min after failure was reached. Subjects reported the duration of time required to subjectively fully recover from this activity. Choices of "less than 1 day," "1 day," "2 days," etc., up to "greater than 2 wk" were given to the subjects for their response. Analysis was by nonparametric ANOVA and appropriate post hoc comparison procedures. Unstable postpolio subjects reported a greater recovery time than either the stable postpolio or control subjects (mean +/- SD of 2.6 +/- 3.0 days, 0.6 +/- 1.0 days, and 0.7 +/- 1.1 days, respectively, P postpolio subjects than stable postpolio or control subjects. The cause for this finding is unknown and requires further investigation.

  12. The influence of isometric exercises of the quadriceps muscle on young female patients with anterior knee pain

    Directory of Open Access Journals (Sweden)

    Jacek Wilczyński

    2015-10-01

    Full Text Available Introduction: Anterior knee pain is a disease associated with abnormalities in the patellofemoral joint. It is a common reason for seeking advice from an orthopaedist. This problem is characterised by chronic pain in the anterior part of one or both knees. This issue often affects women, especially at a young age. The effect of this ailment is deterioration of the quality of life. This dysfunction significantly reduces abilities, and often prevents the performance of daily activities. Pain usually occurs during physical activity, but may also be accompanied by prolonged immobilisation of the knee joint. In defining the type of patellofemoral instability, orthopaedists use magnetic resonance imaging, arthroscopy, ultrasonography, and X-ray examination. A relatively effective method of treatment of pain in the patellofemoral joint is through isometric exercises of the quadriceps. They increase the strength of the quadriceps femoris muscle and reduce instability in the patellofemoral joint. Aim of the research: To evaluate the effectiveness of isometric exercises of the quadriceps muscle on young female patients with anterior knee pain. Material and methods : The study involved 30 women aged 13–44 years (mean age: 26.8 years, who had been diagnosed with pain in the front of the knee. Results and conclusions: Isometric exercises of the quadriceps muscle are an effective method of reducing anterior knee pain. Isometric exercises have a beneficial influence on improving physical activity, including performing basic activities of daily living. Student’s t distribution showed, that isometric exercises of the quadriceps muscle reduce pain at the front of the knee. Kruskal-Wallis test confirmed a significant reduction of anterior knee pain.

  13. Evaluating the subject-performed task effect in healthy older adults: relationship with neuropsychological tests

    Directory of Open Access Journals (Sweden)

    Ana Rita Silva

    2015-04-01

    Full Text Available Background: An enhancement in recall of simple instructions is found when actions are performed in comparison to when they are verbally presented – the subject-performed task (SPT effect. This enhancement has also been found with older adults. However, the reason why older adults, known to present a deficit in episodic memory, have a better performance for this type of information remains unclear. In this article, we explored this effect by comparing the performance on the SPT task with the performance on other tasks, in order to understand the underlying mechanisms that may explain this effect. Objective: We hypothesized that both young and older adult groups should show higher recall in SPT compared with the verbal learning condition, and that the differences between age groups should be lower in the SPT condition. We aimed to explore the correlations between these tasks and known neuropsychological tests, and we also measured source memory for the encoding condition. Design: A mixed design was used with 30 healthy older adults, comparing their performance with 30 healthy younger adults. Each participant was asked to perform 16 simple instructions (SPT condition and to only read the other 16 instructions (Verbal condition – VT. The test phase included a free recall task. Participants were also tested with a set of neuropsychological measures (speed of processing, working memory and verbal episodic memory. Results: The SPT effect was found for both age groups; but even for SPT materials, group differences in recall persisted. Source memory was found to be preserved for the two groups. Simple correlations suggested differences in correlates of SPT performance between the two groups. However, when controlling for age, the SPT and VT tasks correlate with each other, and a measure of episodic memory correlated moderately with both SPT and VT performance. Conclusions: A strong effect of SPT was observed for all but one, which still displayed the

  14. Improvements in Force Variability and Structure from Vision- to Memory-Guided Submaximal Isometric Knee Extension in Subacute Stroke.

    Science.gov (United States)

    Chow, John W; Stokic, Dobrivoje S

    2017-11-02

    We examined changes in variability, accuracy, frequency composition, and temporal regularity of force signal from vision-guided to memory-guided force-matching tasks in 17 subacute stroke and 17 age-matched healthy subjects. Subjects performed a unilateral isometric knee extension at 10%, 30%, and 50% of peak torque (MVC) for 10 s (3 trials each). Visual feedback was removed at the 5s-mark in the first 2 trials (feedback withdrawal), and 30 s after the second trial the subjects were asked to produce the target force without visual feedback (force recall). The coefficient of variation and constant error were used to quantify force variability and accuracy. Force structure was assessed by the median frequency, relative spectral power in the 0-3 Hz band, and sample entropy of the force signal. At 10% MVC, the force signal in subacute stroke subjects became steadier, more broadband, and temporally more irregular after the withdrawal of visual feedback, with progressively larger error at higher contraction levels. Also, the lack of modulation in the spectral frequency at higher force levels with visual feedback persisted in both the withdrawal and recall conditions. In terms of changes from the visual feedback condition, the feedback withdrawal produced a greater difference between the paretic, non-paretic, and control legs than the force recall. The overall results suggest improvements in force variability and structure from vision- to memory-guided force control in subacute stroke despite decreased accuracy. Different sensory-motor memory retrieval mechanisms seem to be involved in the feedback withdrawal and force recall conditions, which deserves further studies.

  15. Occupational performance in daily life activities of subjects hospitalized because of chronic malnutrition

    Directory of Open Access Journals (Sweden)

    Lauren Machado Pinto

    2013-08-01

    Full Text Available : Introduction: Malnutrition is configured as a health condition that causes deficits in occupational performance. Objective: To establish a correlation between nutritional status and occupational performance in activities of daily life (ADLs according to the desnutrition state level. Methodology: A descriptive, exploratory, cross-sectional evaluation of 50 patients diagnosed with chronic malnutrition admitted to a University Hospital in Curitiba, Parana state. We used the Functional Independence Measure (FIM and a semi-structured questionnaire in which the subjects named the three main performance limiting reasons. The Kruskal-Wallis test was used to identify the existence of differences between at least two groups in the analysis, while the test of Multiple Comparisons was used to determine which pairs of groups showed statistically significant differences at 95% significance level (p ≤ 0.05. Results: We assessed 28 (56% female and 22 (44% male patients with mean age of 50.16 (±16.74 for one year. Out of these, 19 (38% presented mild chronic malnutrition, 16 (32% showed moderate chronic malnutrition, and 14 (28% presented severe chronic malnutrition. We identified changes particularly in activities evaluated in the use of motor FIM, with relevant alterations of dependence level for the states of moderate to severe malnutrition. Patients’ complaints were in agreement with those pointed by the literature as symptoms of malnutrition. Conclusion: This study confirms the correlation between deterioration in nutritional status and high dependence level upon ADLs.

  16. Effort provides its own reward: endeavors reinforce subjective expectation and evaluation of task performance.

    Science.gov (United States)

    Wang, Lei; Zheng, Jiehui; Meng, Liang

    2017-04-01

    Although many studies have investigated the relationship between the amount of effort invested in a certain task and one's attitude towards the subsequent reward, whether exerted effort would impact one's expectation and evaluation of performance feedback itself still remains to be examined. In the present study, two types of calculation tasks that varied in the required effort were adopted, and we resorted to electroencephalography to probe the temporal dynamics of how exerted effort would affect one's anticipation and evaluation of performance feedback. In the high-effort condition, a more salient stimulus-preceding negativity was detected during the anticipation stage, which was accompanied with a more salient FRN/P300 complex (a more positive P300 and a less negative feedback-related negativity) in response to positive outcomes in the evaluation stage. These results suggested that when more effort was invested, an enhanced anticipatory attention would be paid toward one's task performance feedback and that positive outcomes would be subjectively valued to a greater extent.

  17. Performance of Hybrid Steel Fibers Reinforced Concrete Subjected to Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Mohammed Alias Yusof

    2013-01-01

    Full Text Available This paper presents the results of the experimental data and simulation on the performance of hybrid steel fiber reinforced concrete (HSFRC and also normal reinforced concrete (NRC subjected to air blast loading. HSFRC concrete mix consists of a combination of 70% long steel hook end fibre and also 30% of short steel hook end fibre with a volume fraction of 1.5% mix. A total of six concrete panels were subjected to air blast using plastic explosive (PE4 weighing 1 kg each at standoff distance of 0.3 meter. The parameters measured are mode of failure under static and blast loading and also peak overpressure that resulted from detonation using high speed data acquisition system. In addition to this simulation work using AUTODYN was carried out and validated using experimental data. The experimental results indicate that hybrid steel fiber reinforced concrete panel (HSFRC possesses excellent resistance to air blast loading as compared to normal reinforced concrete (NRC panel. The simulation results were also found to be close with experimental data. Therefore the results have been validated using experimental data.

  18. COMT Val158Met modulates subjective responses to intravenous nicotine and cognitive performance in abstinent smokers

    Science.gov (United States)

    Herman, Aryeh I.; Jatlow, Peter I.; Gelernter, Joel; Listman, Jennifer B.; Sofuoglu, Mehmet

    2013-01-01

    The COMT Val158Met polymorphism may be a risk factor for nicotine addiction. This study examined the influence of the COMT Val158Met polymorphism on subjective, physiological, and cognitive effects of intravenous (IV) nicotine use in African American (AAs) (n=56) and European American (EAs) (n=68) smokers. Overnight abstinent smokers received saline followed by 0.5 and 1.0 mg/70 kg doses of nicotine, administered 30 minutes apart. Smokers with Val/Val genotype, compared to Met carriers, had greater negative subjective effects from IV nicotine and had more severe withdrawal severity following overnight abstinence from smoking. Women with Val/Val genotype reported greater difficulty concentrating and irritability than men with Val/Val or Met carrier genotypes. The Val/Val genotype was associated with better performance on the math task and in AA smokers it was associated with greater systolic blood pressure. These results support the rationale of pharmacologically inhibiting COMT to aid with smoking cessation among Val/Val genotype smokers. PMID:23459442

  19. Subjective Preference of Cellists for the Delay Time of a Single Reflection in a Performance

    Science.gov (United States)

    SATO, S.; ANDO, Y.; OTA, S.

    2000-04-01

    To provide knowledge useful in designing the stage enclosure in a concert hall, Nakayama reported the subjective preference of alto-recorder players for sound fields with a single reflection [Acustica54, 217-221 (1984)]. The present study evaluates the subjective preferences, with regard to ease of performance, of five cello soloists for the delay time of a single reflection. The scale values of preference for the delay time of a single reflection were obtained using a paired comparison method, and the results were compared with those for the alto-recorder players and listeners. The scale values of preference for both individuals and for global cellists with regard to the delay time of reflection can be expressed by a single approximate formula, normalizing the delay time by the most-preferred delay time observed for different music motifs. A notable finding is that the most-preferred delay time of a single reflection for each cellist can be calculated from the amplitude of the reflection and the minimum value of the effective duration (τe)minof the running autocorrelation function of the music motifs played by each cellist.

  20. Life events, salivary cortisol, and cognitive performance in nondemented subjects: a population-based study.

    Science.gov (United States)

    Ouanes, Sami; Castelao, Enrique; Gebreab, Sirak; von Gunten, Armin; Preisig, Martin; Popp, Julius

    2017-03-01

    Older people are particularly exposed to stressful events, known to activate the hypothalamus-pituitary-adrenal axis resulting in increased cortisol levels. High cortisol has been associated with deleterious effects on cognition. We hypothesized that stressful life events could increase cortisol secretion leading to cognitive impairment. A cross-sectional analysis was conducted using data from Colaus/PsyColaus, a longitudinal population-based study among Lausanne residents. Salivary cortisol samples were obtained from 796 nondemented subjects aged at least 65. A neuropsychological battery was used to assess cognitive performance and determine the Clinical Dementia Rating Sum of Boxes (CDRSOB). Lifetime life events and their subjective impact were assessed using a validated questionnaire. The total impact of life events was associated neither with cortisol area under the curve (AUC) nor with CDRSOB nor with any cognitive domain performance. The CDRSOB was associated with the cortisol AUC, controlling for age, sex, body mass index, education and depressive symptoms (p = 0.003; B = 0.686 [0.240; 1.333]; r = 0.114). This association between CDRSOB and the cortisol AUC remained significant after controlling for life events total impact (p = 0.040; B = 0.591 [0.027; 1.155]; r = 0.106). These findings do not support the hypothesis that stressful life events increase cortisol secretion leading to cognitive impairment. The association of higher cortisol levels with poorer cognition might be not a mere reflection of stressful events but rather explained by other factors, yet to be elucidated. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Metformin improves performance in high-intensity exercise, but not anaerobic capacity in healthy male subjects.

    Science.gov (United States)

    Learsi, S K; Bastos-Silva, V J; Lima-Silva, A E; Bertuzzi, R; De Araujo, G G

    2015-10-01

    The aim of this study was to determine the ergogenic effects of metformin in high-intensity exercise, as well as its effects on anaerobic capacity, in healthy and physically active men. Ten subjects (mean (± standard deviation) maximal oxygen uptake (V˙O2max ) 38.6 ± 4.5 mL/kg per min) performed the following tests in a cycle ergometer: (i) an incremental test; (ii) six submaximal constant workload tests at 40%-90% (V˙O2max ); and (iii) two supramaximal tests (110% (V˙O2max ). Metformin (500 mg) or placebo was ingested 60 min before the supramaximal test. There were no significant differences between the placebo and metformin groups in terms of maximum accumulated oxygen deficit (2.8 ± 0.6 vs 3.0 ± 0.8 L, respectively; P = 0.08), lactate concentrations (7.8 ± 2.6 vs 7.5 ± 3.0 mmol/L, respectively; P = 0.75) or O2 consumed in either the last 30 s of exercise (40.4 ± 4.4 vs 39.9 ± 4.0 mL/kg per min, respectively; P = 0.35) or the first 110 s of exercise (29.0 ± 2.5 vs 29.5 ± 3.0 mL/kg per min, respectively; P = 0.42). Time to exhaustion was significantly higher after metformin than placebo ingestion (191 ± 33 vs 167 ± 32 s, respectively; P = 0.001). The fast component of V˙O2 recovery was higher in the metformin than placebo group (12.71 vs 12.18 mL/kg per min, respectively; P = 0.025). Metformin improved performance and anaerobic alactic contribution during high-intensity exercise, but had no effect on overall anaerobic capacity in healthy subjects. © 2015 Wiley Publishing Asia Pty Ltd.

  2. Cerebral mechanisms underlying the effects of music during a fatiguing isometric ankle-dorsiflexion task.

    Science.gov (United States)

    Bigliassi, Marcelo; Karageorghis, Costas I; Nowicky, Alexander V; Orgs, Guido; Wright, Michael J

    2016-10-01

    The brain mechanisms by which music-related interventions ameliorate fatigue-related symptoms during the execution of fatiguing motor tasks are hitherto under-researched. The objective of the present study was to investigate the effects of music on brain electrical activity and psychophysiological measures during the execution of an isometric fatiguing ankle-dorsiflexion task performed until the point of volitional exhaustion. Nineteen healthy participants performed two fatigue tests at 40% of maximal voluntary contraction while listening to music or in silence. Electrical activity in the brain was assessed by use of a 64-channel EEG. The results indicated that music downregulated theta waves in the frontal, central, and parietal regions of the brain during exercise. Music also induced a partial attentional switching from associative thoughts to task-unrelated factors (dissociative thoughts) during exercise, which led to improvements in task performance. Moreover, participants experienced a more positive affective state while performing the isometric task under the influence of music. © 2016 Society for Psychophysiological Research.

  3. The effect of short-term isometric training on core/torso stiffness.

    Science.gov (United States)

    Lee, Benjamin; McGill, Stuart

    2017-09-01

    "Core" exercise is a basic part of many physical training regimens with goals ranging from rehabilitation of spine and knee injuries to improving athletic performance. Core stiffness has been proposed to perform several functions including reducing pain by minimising joint micro-movements, and enhancing strength and speed performance. This study probes the links between a training approach and immediate but temporary changes in stiffness. Passive and active stiffness was measured on 24 participants; 12 having little to no experience in core training (inexperienced), and the other 12 being athletes experienced to core training methods; before and after a 15 min bout of isometric core exercises. Passive stiffness was assessed on a "frictionless" bending apparatus and active stiffness assessed via a quick release mechanism. Short-term isometric core training increased passive and active stiffness in most directions for both inexperienced and experienced participants, passive left lateral bend among experienced participants being the exception (P core stiffness, in this case following a single session. This may influence performance and injury resilience for a brief period.

  4. Acute Effects of the Different Intensity of Static Stretching on Flexibility and Isometric Muscle Force.

    Science.gov (United States)

    Kataura, Satoshi; Suzuki, Shigeyuki; Matsuo, Shingo; Hatano, Genki; Iwata, Masahiro; Yokoi, Kazuaki; Tsuchida, Wakako; Banno, Yasuhiro; Asai, Yuji

    2017-12-01

    Kataura, S, Suzuki, S, Matsuo, S, Hatano, G, Iwata, M, Yokoi, K, Tsuchida, W, Banno, Y, and Asai, Y. Acute effects of the different intensity of static stretching on flexibility and isometric muscle force. J Strength Cond Res 31(12): 3403-3410, 2017-In various fields, static stretching is commonly performed to improve flexibility, whereas the acute effects of different stretch intensities are unclear. Therefore, we investigated the acute effects of different stretch intensities on flexibility and muscle force. Eighteen healthy participants (9 men and 9 women) performed 180-second static stretches of the right hamstrings at 80, 100, and 120% of maximum tolerable intensity without stretching pain, in random order. The following outcomes were assessed as markers of lower limb function and flexibility: static passive torque (SPT), range of motion (ROM), passive joint (muscle-tendon) stiffness, passive torque (PT) at onset of pain, and isometric muscle force. Static passive torque was significantly decreased after all stretching intensities (p ≤ 0.05). Compared with before stretching at 100 and 120% intensities, ROM and PT were significantly increased after stretching (p ≤ 0.05), and passive stiffness (p = 0.05) and isometric muscle force (p ≤ 0.05) were significantly decreased. In addition, ROM was significantly greater after stretching at 100 and 120% than at 80%, and passive stiffness was significantly lower after 120% than after 80% (p ≤ 0.05). However, all measurements except SPT were unchanged after 80% intensity. There was a weak positive correlation between the intensities of stretching and the relative change for SPT (p ≤ 0.05), a moderate positive correlation with ROM (p ≤ 0.05), and a moderate positive correlation with passive stiffness (p ≤ 0.05). These results indicate that static stretching at greater intensity is more effective for increasing ROM and decreasing passive muscle-tendon stiffness.

  5. Functional and muscular adaptations in an experimental model for isometric strength training in mice.

    Directory of Open Access Journals (Sweden)

    Karsten Krüger

    Full Text Available Exercise training induces muscular adaptations that are highly specific to the type of exercise. For a systematic study of the differentiated exercise adaptations on a molecular level mouse models have been used successfully. The aim of the current study was to develop a suitable mouse model of isometric strength exercise training characterized by specific adaptations known from strength training. C57BL/6 mice performed an isometric strength training (ST for 10 weeks 5 days/week. Additionally, either a sedentary control group (CT or a regular endurance training group (ET groups were used as controls. Performance capacity was determined by maximum holding time (MHT and treadmill spirometry, respectively. Furthermore, muscle fiber types and diameter, muscular concentration of phosphofructokinase 1 (PFK, succinate dehydrogenase (SDHa, and glucose transporter type 4 (GLUT4 were determined. In a further approach, the effect of ST on glucose intolerance was tested in diabetic mice. In mice of the ST group we observed an increase of MHT in isometric strength tests, a type II fiber hypertrophy, and an increased GLUT4 protein content in the membrane fraction. In contrast, in mice of the ET group an increase of VO(2max, a shift to oxidative muscle fiber type and an increase of oxidative enzyme content was measured. Furthermore strength training was effective in reducing glucose intolerance in mice fed a high fat diet. An effective murine strength training model was developed and evaluated, which revealed marked differences in adaptations known from endurance training. This approach seems also suitable to test for therapeutical effects of strength training.

  6. Isokinetic and Isometric Muscle Strength in a Healthy Population – with Special Reference to Age and Gender

    DEFF Research Database (Denmark)

    Danneskiold-Samsøe, B; Bartels, E M; Bülow, P M

    2009-01-01

    was subgrouped according to age and gender. Isometric and isokinetic muscle strength was measured in each subject across the main joints in the body. A statistical model was developed that encompassed the three main muscle groups: upper limbs, trunk and lower limbs. Results: Muscle strength in healthy men...... the major joint movements of an individual with values for a healthy man or woman at any age in the range of 20–80 years. In all age groups, women have lower muscle strength than men. Men’s muscle strength declines with age, while women’s muscle strength declines from the age of 41 years.......Aim: Muscle strength is an excellent indicator of general health when based on reliable measurements. Muscle strength data for a healthy population are rare or non-existent. The aim of the present study was to measure a set of normal values for isometric and isokinetic muscle strength for all...

  7. Acute effect of whole body vibration on isometric strength, squat jump, and flexibility in well-trained combat athletes

    Directory of Open Access Journals (Sweden)

    Cem Kurt

    2015-02-01

    Full Text Available The purpose of this study was to investigate the effect of whole body vibration (WBV training on maximal strength, squat jump, and flexibility of well-trained combat athletes. Twelve female and 8 male combat athletes (age: 22.8 ± 3.1 years, mass: 65.4 ± 10.7 kg, height: 168.8 ± 8.8 cm, training experience: 11.6 ± 4.7 years, training volume: 9.3 ± 2.8 hours/week participated in this study. The study consisted of three sessions separated by 48 hours. The first session was conducted for familiarization. In the subsequent two sessions, participants performed WBV or sham intervention in a randomized, balanced order. During WBV intervention, four isometric exercises were performed (26 Hz, 4 mm. During the sham intervention, participants performed the same WBV intervention without vibration treatment (0 Hz, 0 mm. Hand grip, squat jump, trunk flexion, and isometric leg strength tests were performed after each intervention. The results of a two-factor (pre-post[2] × intervention[2] repeated measures ANOVA revealed a significant interaction (p = 0.018 of pre-post × intervention only for the hand grip test, indicating a significant performance increase of moderate effect (net increase of 2.48%, d = 0.61 after WBV intervention. Squat jump, trunk flexion, and isometric leg strength performances were not affected by WBV. In conclusion, the WBV protocol used in this study potentiated hand grip performance, but did not enhance squat jump, trunk flexion, or isometric leg strength in well-trained combat athletes.

  8. Objective and subjective assessments of lighting in a hospital setting: implications for health, safety and performance.

    Science.gov (United States)

    Dianat, Iman; Sedghi, Ali; Bagherzade, Javad; Jafarabadi, Mohammad Asghari; Stedmon, Alex W

    2013-01-01

    A field study was conducted to evaluate the illumination levels, to examine the effect of lighting conditions (including lighting characteristics and disturbances) on employee satisfaction, job performance, safety and health, and to compare the employees' perception of lighting level with actual illuminance levels in a hospital setting using both questionnaire and physical illuminance measurements. The illumination levels varied across different locations within the hospital and were lower than standards for 52.2% of the workplaces surveyed. Most respondents indicated that at least one of the four lighting characteristics (i.e. light level, type of light sources, light colour and use of daylight) was inappropriate, and that at least one of the three lighting disturbances (i.e. flickering lights, glare and unwanted shadows) was a major disturbance to them. The employees' perceptions of illuminance generally reflected the actual illuminance levels. The more appropriate maintenance or installation of lighting fixtures was rated as the most appropriate for improving lighting. The findings suggest that environmental ergonomics should be given a more prominent role in hospital building and workplace design to support safer healthcare facilities (for staff and potentially for patients). Good lighting is essential to improve employee performance, health and safety. The findings suggest that quantitative physical measurements should be supplemented by qualitative subjective assessments to provide a more holistic approach where specific details about the lighting condition in each working environment are incorporated from the workers' perspective.

  9. Functional asymmetries in early learning during right, left, and bimanual performance in right-handed subjects.

    Science.gov (United States)

    Aznárez-Sanado, Maite; Fernández-Seara, Maria A; Loayza, Francis R; Pastor, Maria A

    2013-03-01

    To elucidate differences in activity and connectivity during early learning due to the performing hand. Twenty right-handed subjects were recruited. The neural correlates of explicit visuospatial learning executed with the right, the left hand, and bimanually were investigated using functional magnetic resonance imaging. Connectivity analyses were carried out using the psychophysiological interactions model, considering right and left anterior putamen as index regions. A common neural network was found for the three tasks during learning. Main activity increases were located in posterior cingulate cortex, supplementary motor area, parietal cortex, anterior putamen, and cerebellum (IV-V), whereas activity decrements were observed in prefrontal regions. However, the left hand task showed a greater recruitment of left hippocampal areas when compared with the other tasks. In addition, enhanced connectivity between the right anterior putamen and motor cortical and cerebellar regions was found for the left hand when compared with the right hand task. An additional recruitment of brain regions and increased striato-cortical and striato-cerebellar functional connections is needed when early learning is performed with the nondominant hand. In addition, access to brain resources during learning may be directed by the dominant hand in the bimanual task. Copyright © 2012 Wiley Periodicals, Inc.

  10. Stability Criterion of Linear Stochastic Systems Subject to Mixed H2/Passivity Performance

    Directory of Open Access Journals (Sweden)

    Cheung-Chieh Ku

    2015-01-01

    Full Text Available The H2 control scheme and passivity theory are applied to investigate the stability criterion of continuous-time linear stochastic system subject to mixed performance. Based on the stochastic differential equation, the stochastic behaviors can be described as multiplicative noise terms. For the considered system, the H2 control scheme is applied to deal with the problem on minimizing output energy. And the asymptotical stability of the system can be guaranteed under desired initial conditions. Besides, the passivity theory is employed to constrain the effect of external disturbance on the system. Moreover, the Itô formula and Lyapunov function are used to derive the sufficient conditions which are converted into linear matrix inequality (LMI form for applying convex optimization algorithm. Via solving the sufficient conditions, the state feedback controller can be established such that the asymptotical stability and mixed performance of the system are achieved in the mean square. Finally, the synchronous generator system is used to verify the effectiveness and applicability of the proposed design method.

  11. Performance Evaluation on Transmission Tower-Line System with Passive Friction Dampers Subjected to Wind Excitations

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2015-01-01

    Full Text Available The vibration control and performance evaluation on a transmission-tower line system by using friction dampers subjected to wind excitations are carried out in this study. The three-dimensional finite element (FE model of a transmission tower is firstly constructed. A two-dimensional lumped mass model of a transmission tower is developed for dynamic analysis. The analytical model of transmission tower-line system is proposed by taking the dynamic interaction between the tower and the transmission lines into consideration. The mechanical model of passive friction damper is presented by involving the effects of damper axial stiffness. The equation of motion of the transmission tower-line system incorporated with the friction dampers disturbed by wind excitations is established. A real transmission tower-line system is taken as an example to examine the feasibility and reliability of the proposed control approach. An extensive parameter study is carried out to find the optimal parameters of friction damper and to assess the effects of slipping force axial stiffness and hysteresis loop on control performance. The work on an example structure indicates that the application of friction dampers with optimal parameters could significantly reduce wind-induced responses of the transmission tower-line system.

  12. Intrarater reliability of hand held dynamometry in measuring lower extremity isometric strength using a portable stabilization device.

    Science.gov (United States)

    Jackson, Steven M; Cheng, M Samuel; Smith, A Russell; Kolber, Morey J

    2017-02-01

    Hand held dynamometry (HHD) is a more objective way to quantify muscle force production (MP) compared to traditional manual muscle testing. HHD reliability can be negatively impacted by both the strength of the tester and the subject particularly in the lower extremities due to larger muscle groups. The primary aim of this investigation was to assess intrarater reliability of HHD with use of a portable stabilization device for lower extremity MP in an athletic population. Isometric lower extremity strength was measured for bilateral lower extremities including hip abductors, external rotators, adductors, knee extensors, and ankle plantar flexors was measured in a sample of healthy recreational runners (8 male, 7 females, = 30 limbs) training for a marathon. These measurements were assessed using an intrasession intrarater reliability design. Intraclass correlation coefficients (ICC) were calculated using 3,1 model based on the single rater design. The standard error of measurement (SEM) for each muscle group was also calculated. ICC were excellent ranging from ICC (3,1) = 0.93-0.98 with standard error of measurements ranging from 0.58 to 17.2 N. This study establishes the use of a HHD with a portable stabilization device as demonstrating good reliability within testers for measuring lower extremity muscle performance in an active healthy population. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Is the firing rate of motor units in different vastus medialis regions modulated similarly during isometric contractions?

    Science.gov (United States)

    Cabral, Hélio V; de Souza, Leonardo M L; Mello, Roger G T; Gallina, Alessio; de Oliveira, Liliam F; Vieira, Taian M

    2018-02-01

    Previous evidence suggests the fibers of different motor units reside within distinct vastus medialis (VM) regions. It remains unknown whether the activity of these motor units may be modulated differently. Herein we assess the discharge rate of motor units detected proximodistally from the VM to address this issue. Surface electromyograms (EMGs) were recorded proximally and distally from the VM while 10 healthy subjects performed isometric contractions. Single motor units were decomposed from surface EMGs. The smoothed discharge rates of motor units identified from the same and from different VM regions were then cross-correlated. During low-level contractions, the discharge rate varied more similarly for distal (cross-correlation peak; interquartile interval: 0.27-0.40) and proximal (0.28-0.52) than for proximodistal pairs of VM motor units (0.20-0.33; P = 0.006). The discharge rates of motor units from different proximodistal VM regions show less similarity in their variations than those of pairs of units either distally or proximally. Muscle Nerve 57: 279-286, 2018. © 2017 Wiley Periodicals, Inc.

  14. Handgrip and general muscular strength and endurance during prolonged bedrest with isometric and isotonic leg exercise training

    Science.gov (United States)

    Greenleaf, J. E.; Starr, J. C.; Van Beaumont, W.; Convertino, V. A.

    1983-01-01

    Measurements of maximal grip strength and endurance at 40 percent max strength were obtained for 7 men 19-21 years of age, 1-2 days before and on the first recovery day during three 2-week bedrest (BR) periods, each separated by a 3-week ambulatory recovery period. The subjects performed isometric exercise (IME) for 1 hr/day, isotonic exercise (ITE) for 1 hr/day, and no exercise (NOE) in the three BR periods. It was found that the mean maximal grip strength was unchanged after all three BR periods. Mean grip endurance was found to be unchanged after IME and ITE training, but was significantly reduced after NOE. These results indicate that IME and ITE training during BR do not increase or decrease maximal grip strength, alghough they prevent loss of grip endurance, while the maximal strength of all other major muscle groups decreases in proportion to the length of BR to 70 days. The maximal strength reduction of the large muscle groups was found to be about twice that of the small muscle groups during BR. In addition, it is shown that changes in maximal strength after spaceflight, BR, or water immersion deconditioning cannot be predicted from changes in submaximal or maximal oxygen uptake values.

  15. Differences in performance on the functional movement screen between chronic low back pain patients and healthy control subjects

    OpenAIRE

    Ko, Min-Joo; Noh, Kyung-Hee; Kang, Min-Hyeok; Oh, Jae-Seop

    2016-01-01

    [Purpose] Differences in scores on the Functional Movement Screen between patients with chronic lower back pain and healthy control subjects were investigated. [Subjects and Methods] In all, 20 chronic lower back pain patients and 20 healthy control subjects were recruited. Chronic lower back pain patients and healthy controls performed the Functional Movement Screen (deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability pushup, and rotary stabil...

  16. Effects of electromyostimulation versus voluntary isometric training on elbow flexor muscle strength.

    Science.gov (United States)

    Colson, Serge S; Martin, Alain; Van Hoecke, Jacques

    2009-10-01

    The purpose of this study was to determine whether 7 weeks of standardized (same number and duration of repetitions, sets and rest strictly identical) electromyostimulation training of the elbow flexor muscles would induce strength gains equivalent to those of voluntary isometric training in isometric, eccentric and concentric contractions. Twenty-five males were randomly assigned to an electromyostimulated group (EMS, n=9), a voluntary isometric group (VOL, n=8), or a control group (CON, n=8). Maximal voluntary isometric, eccentric and concentric strength, electromyographic (EMG) activity of the biceps and triceps brachii muscles, elbow flexor muscle activation (twitch interpolation technique) and contractile properties were assessed before and after the training period. The main findings were that the isometric torque gains of EMS were greater than those of VOL after the training period (Pelectromyostimulation training would be more efficient than voluntary isometric training to improve both isometric and dynamic strength.

  17. Comparison of the Hang High-Pull and Loaded Jump Squat for the Development of Vertical Jump and Isometric Force-Time Characteristics.

    Science.gov (United States)

    Oranchuk, Dustin J; Robinson, Tracey L; Switaj, Zachary J; Drinkwater, Eric J

    2017-04-15

    Weightlifting movements have high skill demands and require expert coaching. Loaded jumps have a comparably lower skill demand, but may be similarly effective for improving explosive performance. The purpose of this study was to compare vertical jump performance, isometric force, and rate of force development (RFD) following a ten-week intervention employing the hang high-pull (hang-pull) or trap-bar jump squat (jump-squat). Eighteen NCAA Division II swimmers (8 males, 10 females) with at least one year of resistance training experience volunteered to participate. Testing included the squat jump (SJ), countermovement jump (CMJ) and the isometric mid-thigh pull (IMTP). Vertical ground reaction forces were analyzed to obtain jump height and relative peak power. Relative peak force, peak RFD and relative force at five time bands were obtained from the IMTP. Subjects were randomly assigned to either a hang-pull (n = 9) or jump-squat (n = 9) training group and completed a ten-week, volume-equated, periodized training program. While there was a significant main effect of training for both groups, no statistically significant between-group differences were found (p ≥ 0.17) for any of the dependent variables. However, medium effect sizes in favor of the jump-squat training group were seen in SJ height (d = 0.56) and SJ peak power (d = 0.69). Loaded jumps seem equally effective as weightlifting derivatives for improving lower-body power in experienced athletes. Since loaded jumps require less skill and less coaching expertise than weightlifting, loaded jumps should be considered where coaching complex movements is difficult.

  18. Isometric multipliers of a vector valued Beurling algebra on a ...

    Indian Academy of Sciences (India)

    Abstract. Let (S, ω) be a weighted abelian semigroup, let Mω(S) be the semigroup of ω-bounded multipliers of S, and let A be a strictly convex commutative Banach algebra with identity. It is shown that T is an onto isometric multiplier of l1(S,ω, A) if and only if there exists an invertible σ ∈ Mω(S), a unitary point a ∈ A, and a k ...

  19. Exoskeletal chitin scales isometrically with body size in terrestrial insects.

    Science.gov (United States)

    Lease, Hilary M; Wolf, Blair O

    2010-06-01

    The skeletal system of animals provides the support for a variety of activities and functions. For animals such as mammals, which have endoskeletons, research has shown that skeletal investment (mass) scales with body mass to the 1.1 power. In this study, we ask how exoskeletal investment in insects scales with body mass. We measured the body mass and mass of exoskeletal chitin of 551 adult terrestrial insects of 245 species, with dry masses ranging from 0.0001 to 2.41 g (0.0002-6.13 g wet mass) to assess the allometry of exoskeletal investment. Our results showed that exoskeletal chitin mass scales isometrically with dry body mass across the Insecta as M(chitin) = a M(dry) (b), where b = 1.03 +/- 0.04, indicating that both large and small terrestrial insects allocate a similar fraction of their body mass to chitin. This isometric chitin-scaling relationship was also evident at the taxonomic level of order, for all insect orders except Coleoptera. We additionally found that the relative exoskeletal chitin investment, indexed by the coefficient, a, varies with insect life history and phylogeny. Exoskeletal chitin mass tends to be proportionally less and to increase at a lower rate with mass in flying than in nonflying insects (M(flying insect chitin) = -0.56 x M(dry) (0.97); M(nonflying insect chitin) = -0.55 x M(dry) (1.03)), and to vary with insect order. Isometric scaling (b = 1) of insect exoskeletal chitin suggests that the exoskeleton in insects scales differently than support structures of most other organisms, which have a positive allometry (b > 1) (e.g., vertebrate endoskeleton, tree secondary tissue). The isometric pattern that we document here additionally suggests that exoskeletal investment may not be the primary limit on insect body size.

  20. The Relationship between Happiness, Subjective Well-Being, Creativity and Job Performance of Primary School Teachers in Ramhormoz City

    Science.gov (United States)

    Jalali, Zohreh; Heidari, Alireza

    2016-01-01

    The research aimed to investigate the relationship between happiness, subjective well-being, creativity and job performance of primary school teachers in Ramhormoz City. Hence, a sample of 330 individuals was selected through random stratified sampling. The research tools included Oxford Happiness Inventory, Subjective Well-being Scale by Keyes…

  1. Effects of a 16-week Pilates exercises training program for isometric trunk extension and flexion strength.

    Science.gov (United States)

    Kliziene, Irina; Sipaviciene, Saule; Vilkiene, Jovita; Astrauskiene, Audrone; Cibulskas, Gintautas; Klizas, Sarunas; Cizauskas, Ginas

    2017-01-01

    To evaluate the effects of Pilates exercises designed to improve isometric trunk extension and flexion strength of muscles in women with chronic low back pain (cLBP). Female volunteers with cLBP were divided into an experimental group (EG; n = 27) and a control group (CG; n = 27). Pilates exercises were performed twice per week by the EG; the duration of each session was 60 min. The program lasted for 16 weeks; thus patients underwent a total of 32 exercise sessions. The maximum isometric waist bending strength of the EG had improved significantly (p = 0.001) after 16 weeks of the Pilates program. The results of trunk flexion muscle endurance tests significantly depended on the trunk extension muscle endurance before the intervention, and at 1 month (r = 0.723, p Pilates exercise program. At the end of the 16-week exercise program, cLBP intensity decreased by 2.01 ± 0.8 (p Pilates exercise program the pain intensified and the functional state deteriorated much faster than the maximum trunk muscle strength. Therefore, it can be concluded that, to decrease pain and improve functional condition, regular exercise (and not only improved strength and endurance) is required. We established that, although the 16-week lumbar stabilization exercise program increased isometric trunk extension and flexion strength and this increase in strength persisted for 2 months, decreased LBP and improved functional condition endured for only 1 month. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Comparison of regression models for estimation of isometric wrist joint torques using surface electromyography

    Directory of Open Access Journals (Sweden)

    Menon Carlo

    2011-09-01

    Full Text Available Abstract Background Several regression models have been proposed for estimation of isometric joint torque using surface electromyography (SEMG signals. Common issues related to torque estimation models are degradation of model accuracy with passage of time, electrode displacement, and alteration of limb posture. This work compares the performance of the most commonly used regression models under these circumstances, in order to assist researchers with identifying the most appropriate model for a specific biomedical application. Methods Eleven healthy volunteers participated in this study. A custom-built rig, equipped with a torque sensor, was used to measure isometric torque as each volunteer flexed and extended his wrist. SEMG signals from eight forearm muscles, in addition to wrist joint torque data were gathered during the experiment. Additional data were gathered one hour and twenty-four hours following the completion of the first data gathering session, for the purpose of evaluating the effects of passage of time and electrode displacement on accuracy of models. Acquired SEMG signals were filtered, rectified, normalized and then fed to models for training. Results It was shown that mean adjusted coefficient of determination (Ra2 values decrease between 20%-35% for different models after one hour while altering arm posture decreased mean Ra2 values between 64% to 74% for different models. Conclusions Model estimation accuracy drops significantly with passage of time, electrode displacement, and alteration of limb posture. Therefore model retraining is crucial for preserving estimation accuracy. Data resampling can significantly reduce model training time without losing estimation accuracy. Among the models compared, ordinary least squares linear regression model (OLS was shown to have high isometric torque estimation accuracy combined with very short training times.

  3. Reliability of isometric trunk moment measurements in healthy persons over 50 years of age.

    Science.gov (United States)

    Kienbacher, Thomas; Paul, Birgit; Habenicht, Richard; Starek, Christian; Wolf, Markus; Kollmitzer, Josef; Ebenbichler, Gerold

    2014-03-01

    To determine the short- and long-term test-retest reliability of maximum isometric trunk moment measurements in healthy volunteers over 50 years of age, to compare these results with those from volunteers younger than 50 years, and to test whether volunteers' anticipatory emotional state affects the precision of these measurements. Forty-two older persons (21 females; age range 50-90 years) and 44 younger persons (19 females; age range 18-49 years) performed maximum isometric trunk extensions, flexions, and rotations using dynamometers (DAVID, Fi, David Health Solutions Ltd, Helsinki, Finland). They repeated the tests after 1-2 days (short-term) and at 6 weeks (long-term). Retest-reliability was evaluated for age- and gender-specific subgroups, with assessment of intraclass correlation coefficient (ICC2,1) , standard error of measurement, smallest real difference, and smallest real difference, in percent. For the elderly group, smallest real difference, in percent values varied up to 33% and were similar to those obtained from young volunteers. Precision of the trunk rotation tests was lower than that of trunk flexion or extension. Retest agreement exceeded 0.75 (ICC2,1) for all tests, with no relevant differences observed between gender- and age-specific subgroups. Neither participants' motivation nor their anticipatory emotions correlated with the individual coefficients of variation of the trunk muscle moment measurements. Isometric maximum trunk extension and flexion moment measurements taken from healthy persons > 50 years old are as reliable as those from persons < 50 years old, and can be expected to enable an acceptable level of detection of expected changes in muscle strength parameters as a result of planned exercise interventions.

  4. Characterizing “fibrofog”: Subjective appraisal, objective performance, and task-related brain activity during a working memory task

    Directory of Open Access Journals (Sweden)

    Brian Walitt

    2016-01-01

    Full Text Available The subjective experience of cognitive dysfunction (“fibrofog” is common in fibromyalgia. This study investigated the relation between subjective appraisal of cognitive function, objective cognitive task performance, and brain activity during a cognitive task using functional magnetic resonance imaging (fMRI. Sixteen fibromyalgia patients and 13 healthy pain-free controls completed a battery of questionnaires, including the Multiple Ability Self-Report Questionnaire (MASQ, a measure of self-perceived cognitive difficulties. Participants were evaluated for working memory performance using a modified N-back working memory task while undergoing Blood Oxygen Level Dependent (BOLD fMRI measurements. Fibromyalgia patients and controls did not differ in working memory performance. Subjective appraisal of cognitive function was associated with better performance (accuracy on the working memory task in healthy controls but not in fibromyalgia patients. In fibromyalgia patients, increased perceived cognitive difficulty was positively correlated with the severity of their symptoms. BOLD response during the working memory task did not differ between the groups. BOLD response correlated with task accuracy in control subjects but not in fibromyalgia patients. Increased subjective cognitive impairment correlated with decreased BOLD response in both groups but in different anatomic regions. In conclusion, “fibrofog” appears to be better characterized by subjective rather than objective impairment. Neurologic correlates of this subjective experience of impairment might be separate from those involved in the performance of cognitive tasks.

  5. Effect of Protectants on the Fermentation Performance of Wine Yeasts Subjected to Osmotic Stress

    Directory of Open Access Journals (Sweden)

    Andrea Caridi

    2003-01-01

    Full Text Available During alcoholic fermentation of must from dried grapes, yeasts are subjected to very high sugar concentrations, besides other environmental stresses, and they modify their metabolic behaviour giving low ethanol yield and abnormally high acetic acid production. To investigate the protective effect of catechin, inositol, and SO2 on wine yeasts, three thermotolerant strains of Saccharomyces cerevisiae, selected for wine making of must from dried grapes, and three strains of Saccharomyces selected for the production of wine, were inoculated in a sample of must at very high osmotic strength. A significant (p<0.01 or p<0.05 relationship between the addition of 100 mg/L of catechin, inositol or SO2 to the grape must and the change in the metabolic behaviour of the yeasts was observed. Compared to the control and depending on strain and protectant, the fermentation rate after 3 days increased up to 55 %, the ethanol content of the wines increased up to 16 %, the unitary succinic acid production increased up to 55 %, the unitary acetic acid production decreased up to 53 %, and the unitary glycerol production decreased up to 69 %. So by adding catechin, inositol or SO2 to the grape must it is possible to minimise the abnormal fermentation performance that wine yeasts exhibit in wine making of must from dried grapes.

  6. Análisis de la fuerza isométrica en la propulsión y tracción en slalom en silla de ruedas y su relación con el rendimiento y la clasificación funcional. [Isometric force in wheelchair slalom during traction and propulsion and their relationship with performance and functional classification].

    Directory of Open Access Journals (Sweden)

    Raúl Reina

    2013-10-01

    profiles of the Cerebral Palsy International Sports and Recreation Association, took part in the study (5 ♂ and 4 ♀. Participants performed two maximal isometric force tests (propulsion and traction with their competition wheelchairs in which maximum force (Fmax, average force (Fmed, execution time and time used to reach different Fmax percentages were recorded. In addition, participants carried out two specific performance tests: a 16 m linear sprint with an inversion door after 8 m; and two 4 m linear displacements with a zig-zag round trip. The measured variable was execution time using photocell gates. Significant differences were found between D3 and D4 in propulsion tests for Fmax (p = 0,007 and Fmean (p = 0,002, being this last one higher. Significant statistical differences were found between D2 and D3 in specific performance tests (inversion: p = 0,034 and zig-zag: p = 0,010, being D3 the quickest group. Results show a non-linear relationship between classification divisions and the performance.http://dx.doi.org/10.5232/ricyde2013.03402

  7. Endurance and fatigue characteristics in the neck muscles during sub-maximal isometric test in patients with cervical radiculopathy.

    Science.gov (United States)

    Halvorsen, Marie; Abbott, Allan; Peolsson, Anneli; Dedering, Åsa

    2014-03-01

    The aim of the study was to compare myoelectric manifestation in neck muscle endurance and fatigue characteristics during sub-maximal isometric endurance test in patients with cervical radiculopathy and asymptomatic subjects. An additional aim was to explore associations between primary neck muscle endurance, myoelectric fatigability, and self-rated levels of fatigue, pain and subjective health measurements in patients with cervical radiculopathy. Muscle fatigue in the ventral and dorsal neck muscles was assessed in patients with cervical radiculopathy and in an asymptomatic group during an isometric neck muscle endurance test in prone and supine. 46 patients and 34 asymptomatic subjects participated. Surface electromyography signals were recorded from the sternocleidomastoid, cervical paraspinal muscles and upper and middle trapezius bilaterally during the endurance test. Subjective health measurements were assessed with questionnaires. The results showed altered neck muscle endurance in several of the muscles investigated with greater negative median frequency slope, greater variability, side imbalance, lower endurance time and higher experience of fatigue among the cervical radiculopathy patients compared with healthy subjects. Endurance times were significantly lower in both prone and in supine positions between the patients compared to asymptomatic subjects. During the neck muscle endurance test, fatigues in the upper trapezius muscles during the prone test and in the sternocleidomastoid muscles during the supine test were of more importance than self-perceived pain, fatigue, disability and kinesiophobia in predicting neck muscle endurance (NME). NME testing in the primary neck muscles seems to be an important factor to take into consideration in rehabilitation.

  8. COMT Val158Met modulates subjective responses to intravenous nicotine and cognitive performance in abstinent smokers

    National Research Council Canada - National Science Library

    Herman, A I; Jatlow, P I; Gelernter, J; Listman, J B; Sofuoglu, M

    2013-01-01

    ...)/Val genotype, compared with methionine (Met) carriers, had greater negative subjective effects from IV nicotine and had more severe withdrawal severity following overnight abstinence from smoking...

  9. Longitudinal Associations of Subjective Memory with Memory Performance and Depressive Symptoms: Between-Person and Within-Person Perspectives

    Science.gov (United States)

    Hülür, Gizem; Hertzog, Christopher; Pearman, Ann; Ram, Nilam; Gerstorf, Denis

    2015-01-01

    Clinical diagnostic criteria for memory loss in adults typically assume that subjective memory ratings accurately reflect compromised memory functioning. Research has documented small positive between-person associations between subjective memory and memory performance in older adults. Less is known, however, about whether within-person fluctuations in subjective memory covary with within-person variance in memory performance and depressive symptoms. The present study applied multilevel models of change to nine waves of data from 27,395 participants of the Health and Retirement Study (HRS; mean age at baseline = 63.78; SD = 10.30; 58% women) to examine whether subjective memory is associated with both between-person differences and within-person variability in memory performance and depressive symptoms and explored the moderating role of known correlates (age, gender, education, and functional limitations). Results revealed that across persons, level of subjective memory indeed covaried with level of memory performance and depressive symptoms, with small-to-moderate between-person standardized effect sizes (0.19 for memory performance and 0.21 for depressive symptoms). Within individuals, occasions when participants scored higher than usual on a test of episodic memory or reported fewer-than-average depressive symptoms generated above-average subjective memory. At the within-person level, subjective memory ratings became more sensitive to within-person alterations in memory performance over time and those suffering from functional limitations were more sensitive to within-person alterations in memory performance and depressive symptoms. We take our results to suggest that within-person changes in subjective memory in part reflect monitoring flux in one’s own memory functioning, but are also influenced by flux in depressive symptoms. PMID:25244464

  10. Perceiving the Causes of Objective and Subjective Outcomes Following Motor Performance

    Science.gov (United States)

    Iso-Ahola, Seppo

    1978-01-01

    Subjective perceptions of outcomes (both success and failure) may vary considerably from those of the experimenter's, and causal attributions are based as much on subject's own perceptions of success and failure as on the experimenter's definitions of outcomes. (Author/MJB)

  11. Impaired cognitive performance in subjects with methamphetamine dependence during exposure to neutral versus methamphetamine-related cues.

    Science.gov (United States)

    Tolliver, Bryan K; Price, Kimber L; Baker, Nathaniel L; LaRowe, Steven D; Simpson, Annie N; McRae-Clark, Aimee L; Saladin, Michael E; DeSantis, Stacia M; Chapman, Elizabeth; Garrett, Margaret; Brady, Kathleen T

    2012-05-01

    Chronic methamphetamine abuse is associated with cognitive deficits that may impede treatment in methamphetamine-dependent patients. Exposure to methamphetamine-related cues can elicit intense craving in chronic users of the drug, but the effects of exposure to drug cues on cognitive performance in these individuals are unknown. This study assessed whether exposure to methamphetamine-related visual cues can elicit craving and/or alter dual task cognitive performance in 30 methamphetamine-dependent subjects and 30 control subjects in the laboratory. Reaction time, response errors, and inhibition errors were assessed on an auditory Go-No Go task performed by adult participants (total N = 60) while watching neutral versus methamphetamine-related video cues. Craving was assessed with the Within-Session Rating Scale modified for methamphetamine-dependent subjects. Exposure to methamphetamine-related cues elicited craving only in methamphetamine-dependent subjects. Even in the absence of methamphetamine cues, methamphetamine-dependent subjects exhibited slower reaction times and higher rates of both inhibition and response errors than control subjects did. Upon exposure to methamphetamine cues, rates of both response errors and inhibition errors increased significantly in methamphetamine-dependent subjects. Control subjects exhibited no increase in inhibition errors and only slightly increased rates of response errors upon exposure to methamphetamine cues. Response error rates, but not inhibition error rates or reaction times, during methamphetamine cue exposure were significantly associated with craving scores in methamphetamine-dependent subjects. Methamphetamine-dependent individuals exhibit cognitive performance deficits that are more pronounced during exposure to methamphetamine-related cues. Interventions that reduce cue reactivity may have utility in the treatment of methamphetamine dependence.

  12. SUBJECTIVITY AND HYBRIDITY IN THE AGE OF INTERACTIVE INTERNET MEDIA: THE MUSICAL PERFORMANCES OF CHARICE PEMPENGCO AND ARNEL PINEDA

    Directory of Open Access Journals (Sweden)

    Christi-Anne Castro

    2010-06-01

    Full Text Available This paper examines hybrid subjectivity in the performances by and in the reception of musical artists utilizing the technology of interactive Internet media. It focuses on the career trajectories of the popular Filipino music performers Charice Pempengco and Arnel Pineda, taking into account how their transnational presence and dissemination through internet media communities affect perceptions of locality, nationality and race.

  13. Performance Levels in Science and Other Subjects for Jamaican Adolescents Attending Single-Sex and Co-Educational High Schools.

    Science.gov (United States)

    Hamilton, Marlene A.

    1985-01-01

    Examination results from 1146 Jamaican high school students in single-sex and coeducational schools indicated students from coeducational schools had lower performance on all measures. A subsample provided more information on sex differences, performance in individual subjects, and students receiving grades of A or B. (DH)

  14. A pilot study to evaluate simulated driving performance and cognitive function in healthy subjects and patients with restless legs syndrome

    Directory of Open Access Journals (Sweden)

    Chen D

    2013-10-01

    Full Text Available Dan Chen,1 Paula Shaw,2 Daniel M Canafax,1,3 James Catesby Ware4 1XenoPort, Inc., Santa Clara, CA, USA; 2Charles River Northwest, Tacoma, WA, USA; 3Theravance Inc., South San Francisco, CA, USA; 4Division of Sleep Medicine, Eastern Virginia Medical School, Norfolk, VA, USA Objective: Symptoms of restless legs syndrome (RLS usually occur during the evening and night time, resulting in disrupted sleep and subsequent daytime fatigue. This study compared simulated driving performance, alertness, and cognitive function between healthy subjects and patients with a diagnosis of RLS. Methods: Fifteen healthy subjects and 15 untreated RLS subjects were enrolled and completed two driving tests. The first test occurred at 4 PM followed by the second test at 8 AM the next morning. Outcome measures included lane position variability (LPV, speed variability, frequency of simulated crashes (off-road events or collision, and brake reaction time. Other assessments included visual analog scale (VAS of alertness and the Brief Assessment of Cognition (BAC. Results: Overall, RLS patients and healthy subjects performed similarly on driving assessments. Two subjects within each group experienced off-road events. RLS patients had less alertness on the VAS than healthy subjects before and after driving assessments. Both groups scored similarly on the cognitive function assessments. Conclusion: Despite reported diminished alertness, RLS patients did not demonstrate impairment in driving or cognitive performance. Keywords: restless legs syndrome, simulated driving performance, cognitive function

  15. Surface electromyogram analysis of the direction of isometric torque generation by the first dorsal interosseous muscle

    Science.gov (United States)

    Zhou, Ping; Suresh, Nina L.; Zev Rymer, William

    2011-06-01

    The objective of this study was to determine whether a novel technique using high density surface electromyogram (EMG) recordings can be used to detect the directional dependence of muscle activity in a multifunctional muscle, the first dorsal interosseous (FDI). We used surface EMG recordings with a two-dimensional electrode array to search for inhomogeneous FDI activation patterns with changing torque direction at the metacarpophalangeal joint, the locus of action of the FDI muscle. The interference EMG distribution across the whole FDI muscle was recorded during isometric contraction at the same force magnitude in five different directions in the index finger abduction-flexion plane. The electrode array EMG activity was characterized by contour plots, interpolating the EMG amplitude between electrode sites. Across all subjects the amplitude of the flexion EMG was consistently lower than that of the abduction EMG at the given force. Pattern recognition methods were used to discriminate the isometric muscle contraction tasks with a linear discriminant analysis classifier, based on the extraction of two different feature sets of the surface EMG signal: the time domain (TD) feature set and a combination of autoregressive coefficients and the root mean square amplitude (AR+RMS) as a feature set. We found that high accuracies were obtained in the classification of different directions of the FDI muscle isometric contraction. With a monopolar electrode configuration, the average overall classification accuracy from nine subjects was 94.1 ± 2.3% for the TD feature set and 95.8 ± 1.5% for the AR+RMS feature set. Spatial filtering of the signal with bipolar electrode configuration improved the average overall classification accuracy to 96.7 ± 2.7% for the TD feature set and 98.1 ± 1.6% for the AR+RMS feature set. The distinct EMG contour plots and the high classification accuracies obtained from this study confirm distinct interference EMG pattern distributions as a

  16. Comparación entre la respuesta de la actividad muscular lumbar en plataforma vibratoria y en ejercicio clásico de squat isométrico en 30º y 60º. (A comparison of the lumbar muscle activity responsein 30º and 60º isometric squat between whole-body vibration and a classic exercise).

    OpenAIRE

    Alejandro Santos-Lozano; Fernanda Santin-Medeiros; Pedro J. Marín; Sonsoles Hernández-Sánchez

    2012-01-01

    Whole-body vibration (WBV) has improved as a variety of exercises, so it is necessary know muscles responses to the vibration stimulus.The aim of this work was to study and to compare the change in muscle activation in the lumbar area and lower body between the whole-body vibration exercise and classic strength exercises in isometric squat.23 subjects were exposed to six different loads in one of each exercise mode: vibration or classic strength. Both exercises were performed at 30º and 60º s...

  17. Water- versus land-based exercise in elderly subjects: effects on physical performance and body composition

    National Research Council Canada - National Science Library

    Bergamin, Marco; Ermolao, Andrea; Tolomio, Silvia; Berton, Linda; Sergi, Giuseppe; Zaccaria, Marco

    2013-01-01

    The aim of this study was to assess the effectiveness of a 24-week exercise protocol carried out in geothermal spring water to improve overall physical function and muscle mass in a group of healthy elderly subjects...

  18. Evaluation of performance, safety, subject acceptance, and compliance of a disposable autoinjector for subcutaneous injections in healthy volunteers.

    Science.gov (United States)

    Berteau, Cecile; Schwarzenbach, Florence; Donazzolo, Yves; Latreille, Mathilde; Berube, Julie; Abry, Herve; Cotten, Joël; Feger, Celine; Laurent, Philippe E

    2010-10-05

    A disposable autoinjector was developed for subcutaneous (SC) self-injection by patients with chronic diseases. To verify its performance and evaluate its acceptance, a clinical study was conducted in healthy volunteers, comparing SC injections performed by subjects using the autoinjector with SC injections performed by nurses using a syringe. This was a randomized, single-center, crossover study comparing SC self-injection using an autoinjector with SC nurse-administered injection using a syringe. Two volumes (0.2 mL and 1 mL) were injected into healthy volunteers. Study objectives included assessment of the accuracy and consistency of the volume injected by the injection systems, and skin reaction and pain associated with the injection. The fluid depot in the SC tissue layer was evaluated by ultrasound. Subject acceptance was evaluated using questionnaires on attitudes and emotions towards the injection technique, and challenged by seeking the subjects' preferred system for a final study injection or future treatment. A total of 960 injections (480 with autoinjector, 480 with syringe) were performed in 40 subjects. There were no significant differences in mean fluid leakage and injected volumes between the systems. Pain associated with the injection was significantly lower with the auto-injector than with the syringe. Local skin reaction at the injection site was overall satisfactory. Injections were appropriately performed by all subjects. At study end, all 40 subjects preferred the autoinjector for a final study injection and for future treatment. This study indicated that the autoinjector used by the subject was similar to a syringe used by a nurse in terms of performance and safety in administering the injections, and better in terms of pain, overall acceptance, and preference.

  19. No Critical Peripheral Fatigue Threshold during Intermittent Isometric Time to Task Failure Test with the Knee Extensors.

    Science.gov (United States)

    Froyd, Christian; Beltrami, Fernando G; Millet, Guillaume Y; Noakes, Timothy D

    2016-01-01

    It has been proposed that group III and IV muscle afferents provide inhibitory feedback from locomotor muscles to the central nervous system, setting an absolute threshold for the development of peripheral fatigue during exercise. The aim of this study was to test the validity of this theory. Thus, we asked whether the level of developed peripheral fatigue would differ when two consecutive exercise trials were completed to task failure. Ten trained sport students performed two exercise trials to task failure on an isometric dynamometer, allowing peripheral fatigue to be assessed 2 s after maximal voluntary contraction (MVC) post task failure. The trials, separated by 8 min, consisted of repeated sets of 10 × 5-s isometric knee extension followed by 5-s rest between contractions. In each set, the first nine contractions were performed at a target force at 60% of the pre-exercise MVC, while the 10th contraction was a MVC. MVC and evoked force responses to supramaximal electrical femoral nerve stimulation on relaxed muscles were assessed during the trials and at task failure. Stimulations at task failure consisted of single stimulus (SS), paired stimuli at 10 Hz (PS10), paired stimuli at 100 Hz (PS100), and 50 stimuli at 100 Hz (tetanus). Time to task failure for the first trial (12.84 ± 5.60 min) was longer (P fatigue. The present data therefore question the existence of a critical peripheral fatigue threshold during intermittent isometric exercise to task failure with the knee extensors.

  20. Avoiding Systematic Errors in Isometric Squat-Related Studies without Pre-Familiarization by Using Sufficient Numbers of Trials

    Directory of Open Access Journals (Sweden)

    Pekünlü Ekim

    2014-10-01

    Full Text Available There is no scientific evidence in the literature indicating that maximal isometric strength measures can be assessed within 3 trials. We questioned whether the results of isometric squat-related studies in which maximal isometric squat strength (MISS testing was performed using limited numbers of trials without pre-familiarization might have included systematic errors, especially those resulting from acute learning effects. Forty resistance-trained male participants performed 8 isometric squat trials without pre-familiarization. The highest measures in the first “n” trials (3 ≤ n ≤ 8 of these 8 squats were regarded as MISS obtained using 6 different MISS test methods featuring different numbers of trials (The Best of n Trials Method [BnT]. When B3T and B8T were paired with other methods, high reliability was found between the paired methods in terms of intraclass correlation coefficients (0.93-0.98 and coefficients of variation (3.4-7.0%. The Wilcoxon’s signed rank test indicated that MISS obtained using B3T and B8T were lower (p < 0.001 and higher (p < 0.001, respectively, than those obtained using other methods. The Bland- Altman method revealed a lack of agreement between any of the paired methods. Simulation studies illustrated that increasing the number of trials to 9-10 using a relatively large sample size (i.e., ≥ 24 could be an effective means of obtaining the actual MISS values of the participants. The common use of a limited number of trials in MISS tests without pre-familiarization appears to have no solid scientific base. Our findings suggest that the number of trials should be increased in commonly used MISS tests to avoid learning effect-related systematic errors

  1. Effects of Knee Position on the Reliability and Production of Maximal and Rapid Strength Characteristics During an Isometric Squat Test.

    Science.gov (United States)

    Palmer, Ty B; Pineda, Jose G; Durham, Rachel M

    2017-10-10

    This study aimed to examine the effects of knee position on the reliability and production of peak force (PF) and rate of force (RFD) development characteristics during an isometric squat. Fourteen resistance-trained females performed isometric squats at 90, 120, and 150° knee angles (corresponding to parallel, half, and quarter squat positions, respectively) on two different occasions, from which PF, peak RFD, and early (RFD30,RFD50,RFD100) and late (RFD200) phase RFD variables were extracted. PF and RFD200 were highly consistent across trials for all three squat positions, with intraclass correlation coefficients (ICCs) ranging between 0.812-0.904 and coefficients of variation (CVs) between 6.6-19.4%. For peak and early RFD characteristics, higher ICCs and lower CV values were observed for the quarter squat (ICCs=0.818-0.852,CVs=17.3-19.4%) compared to the parallel (ICCs=0.591-0.649,CVs=30.1-55.9%) and half squats (ICCs=0.547-0.598,CVs=31.1-34.2%). In addition, isometric PF and RFD200 increased (P≤0.001-0.035) with squat position (parallelperforming isometric squats at higher (150°) rather than lower knee joint angles (90-120°) may provide for an improved capacity to produce greater PF and RFD200 as well as a more reliable testing position for measuring peak and early RFD characteristics.

  2. Evaluation of performance, safety, subject acceptance, and compliance of a disposable autoinjector for subcutaneous injections in healthy volunteers

    OpenAIRE

    Berteau, Cecile; Schwarzenbach, Florence; Donazzolo, Yves; Latreille, Mathilde; Berube, Julie; Abry, Herve; Cotten, Jo?l; Feger, Celine; Laurent, Philippe E

    2010-01-01

    Objective: A disposable autoinjector was developed for subcutaneous (SC) self-injection by patients with chronic diseases. To verify its performance and evaluate its acceptance, a clinical study was conducted in healthy volunteers, comparing SC injections performed by subjects using the autoinjector with SC injections performed by nurses using a syringe. Methods: This was a randomized, single-center, crossover study comparing SC self-injection using an autoinjector with SC nurse-administered ...

  3. Electromyographic and neuromuscular variables in unstable postpolio subjects, stable postpolio subjects, and control subjects.

    Science.gov (United States)

    Rodriquez, A A; Agre, J C; Franke, T M

    1997-09-01

    To compare strength and endurance variables obtained in the quadriceps muscles of postpolio and control subjects over a 7-year interval with macro and single fiber electromyography (EMG) variables. A controlled inception cohort study. Neuromuscular research laboratory of a university hospital. A cohort of 23 postpolio and 14 control subjects. All postpolio subjects had a history, physical examination, and EMG consistent with previous poliomyelitis, and had greater than antigravity strength in the quadriceps muscle tested. Unstable postpolio subjects acknowledged new quadriceps weakness over the 7-year period of the study (n = 11), and stable postpolio subjects denied new weakness of the quadriceps over the same period (n = 12). All subjects had tests of neuromuscular function of the quadriceps muscles at the onset of this study and yearly over a 7-year period. EMG variables were determined on a separate day after the seventh year of neuromuscular measurements. Neuromuscular variables measured were isometric knee extension peak torque, isometric endurance (time to inability to maintain knee extensor contraction at 40% of maximal torque), tension time index (TTI) (product of isometric endurance time and 40% of maximal torque), and recovery of torque at 10 minutes after the endurance test. EMG variables were macro EMG and single fiber EMG (jitter, fiber density, and percent blocking). Unstable postpolio subjects did not lose strength more rapidly than stable postpolio subjects or control subjects. Unstable postpolio subjects were significantly weaker, had decreased TTI, larger macro EMG amplitude, greater jitter, blocking, and fiber density in comparison with stable postpolio subjects (all p postpolio group (p .05) with neuromuscular or EMG variables in control, stable, or unstable postpolio subjects.

  4. A genome-wide supported psychiatric risk variant in NCAN influences brain function and cognitive performance in healthy subjects.

    Science.gov (United States)

    Raum, Heidelore; Dietsche, Bruno; Nagels, Arne; Witt, Stephanie H; Rietschel, Marcella; Kircher, Tilo; Krug, Axel

    2015-01-01

    The A allele of the single nucleotide polymorphism (SNP) rs1064395 in the NCAN gene has recently been identified as a susceptibility factor for bipolar disorder and schizophrenia. NCAN encodes neurocan, a brain-specific chondroitin sulfate proteoglycan that is thought to influence neuronal adhesion and migration. Several lines of research suggest an impact of NCAN on neurocognitive functioning. In the present study, we investigated the effects of rs1064395 genotype on neural processing and cognitive performance in healthy subjects. Brain activity was measured with functional magnetic resonance imaging (fMRI) during an overt semantic verbal fluency task in 110 healthy subjects who were genotyped for the NCAN SNP rs1064395. Participants additionally underwent comprehensive neuropsychological testing. Whole brain analyses revealed that NCAN risk status, defined as AA or AG genotype, was associated with a lack of task-related deactivation in a large left lateral temporal cluster extending from the middle temporal gyrus to the temporal pole. Regarding neuropsychological measures, risk allele carriers demonstrated poorer immediate and delayed verbal memory performance when compared to subjects with GG genotype. Better verbal memory performance was significantly associated with greater deactivation of the left temporal cluster during the fMRI task in subjects with GG genotype. The current data demonstrate that common genetic variation in NCAN influences both neural processing and cognitive performance in healthy subjects. Our study provides new evidence for a specific genetic influence on human brain function. © 2014 Wiley Periodicals, Inc.

  5. Development, validity and reliability of a new pressure air biofeedback device (PAB) for measuring isometric extension strength of the lumbar spine.

    Science.gov (United States)

    Pienaar, Andries W; Barnard, Justhinus G

    2017-04-01

    This study describes the development of a new portable muscle testing device, using air pressure as a biofeedback and strength testing tool. For this purpose, a pressure air biofeedback device (PAB®) was developed to measure and record the isometric extension strength of the lumbar multifidus muscle in asymptomatic and low back pain (LBP) persons. A total of 42 subjects (age 47.58 years, ±18.58) participated in this study. The validity of PAB® was assessed by comparing a selected measure, air pressure force in millibar (mb), to a standard criterion; calibrated weights in kilograms (kg) during day-to-day tests. Furthermore, clinical trial-to-trial and day-to-day tests of maximum voluntary isometric contraction (MVIC) of L5 lumbar multifidus were done to compare air pressure force (mb) to electromyography (EMG) in microvolt (μV) and to measure the reliability of PAB®. A highly significant relationship were found between air pressure output (mb) and calibrated weights (kg). In addition, Pearson correlation calculations showed a significant relationship between PAB® force (mb) and EMG activity (μV) for all subjects (n = 42) examined, as well as for the asymptomatic group (n = 24). No relationship was detected for the LBP group (n = 18). In terms of lumbar extension strength, we found that asymptomatic subjects were significantly stronger than LBP subjects. The results of the PAB® test differentiated between LBP and asymptomatic subject's lumbar isometric extension strength without any risk to the subjects and also indicate that the lumbar isometric extension test with the new PAB® device is reliable and valid.

  6. Secondary School Science Predictors of Academic Performance in University Bioscience Subjects

    Science.gov (United States)

    Green, Rod; Brown, Elizabeth; Ward, Alex

    2009-01-01

    In 2009 the Faculty of Health Sciences at La Trobe University in Melbourne, Australia is introducing a common first year for 11 different undergraduate courses in the faculty. Current prerequisite science entry requirements vary with course and range from none to at least two science or mathematics subjects and from [approximately]50 to 99 in…

  7. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial

    NARCIS (Netherlands)

    van de Rest, O.; Geleijnse, J.M.; Kok, F. J.; van Staveren, W.A.; Dullemeijer, C.; Olde Rikkert, M.G.M.; Beekman, A.T.F.; de Groot, C.P.

    2008-01-01

    Background: High intake of n-3 polyunsaturated fatty acids may protect against age-related cognitive decline. However, results from epidemiologic studies are inconclusive, and results from randomized trials in elderly subjects without dementia are lacking. Objective: To investigate the effect of

  8. Subjective vs objective predictors of functional knee joint performance in anterior cruciate ligament-reconstructed patients

    DEFF Research Database (Denmark)

    Holsgaard-Larsen, Anders; Jensen, Carsten; Aagaard, Per

    2014-01-01

    BACKGROUND: Associations between objective and subjective measures of knee function may facilitate rehabilitation in ACL-patients. AIM: The aim of this study is to investigate if a test-battery of functional and/or muscle outcomes are associated with Knee osteoarthritis outcome score (KOOS) subsc...

  9. Subspecialty Exposure in a Psychiatry Clerkship Does Not Improve Student Performance in the Subject Examination

    Science.gov (United States)

    Retamero, Carolina; Ramchandani, Dilip

    2013-01-01

    Objective: The authors compared the NBME subject examination scores and subspecialty profiles of 3rd-year medical students who were assigned to psychiatry subspecialties during their clerkship with those who were not. Method: The authors collated and analyzed the shelf examination scores, the clinical grades, and the child psychiatry and emergency…

  10. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial.

    NARCIS (Netherlands)

    Rest, O van de; Geleijnse, J.M.; Kok, F.J.; Staveren, W.A. van; Dullemeijer, C.; Olderikkert, M.G.; Beekman, A.T.; Groot, CP de

    2008-01-01

    BACKGROUND: High intake of n-3 polyunsaturated fatty acids may protect against age-related cognitive decline. However, results from epidemiologic studies are inconclusive, and results from randomized trials in elderly subjects without dementia are lacking. OBJECTIVE: To investigate the effect of

  11. Differences between Functional and Subjective Overconfidence in Postdiction Judgments of Test Performance

    Science.gov (United States)

    Shake, Matthew C.; Shulley, Leah J.

    2014-01-01

    Introduction: Recent research has shown that students tend to be overconfident when judging future performance on coursework, particularly students with lower academic ability. Some research suggests that these lower performing students are "doubly cursed" in that they are not only less capable of assessing their own performance, but…

  12. Associations of subjective vitality with DNA damage, cardiovascular risk factors and physical performance

    DEFF Research Database (Denmark)

    Maynard, Scott; Keijzers, Guido; Hansen, A-M

    2015-01-01

    To examine associations of DNA damage, cardiovascular risk factors and physical performance with vitality, in middle-aged men. We also sought to elucidate underlying factors of physical performance by comparing physical performance parameters to DNA damage parameters and cardiovascular risk factors....

  13. A survey on dilations of projective isometric representations

    Directory of Open Access Journals (Sweden)

    Tania-Luminiţa Costache

    2009-01-01

    Full Text Available In this paper we present Laca-Raeburn's dilation theory of projective isometric representations of a semigroup to projective isometric representations of a group [M.Laca and I.Raeburn, Proc. Amer. Math. Soc., 1995] and Murphy's proof of a dilation theorem more general than that proved by Laca and Raeburn. Murphy applied the theory which involves positive definite kernels and their Kolmogorov decompositions to obtain the Laca-Raeburn dilation theorem [G.J. Murphy, Proc. Amer. Math.Soc., 1997]. We also present Heo's dilation theorems for projective representations, which generalize Stinespring dilation theorem for covariant completely positive maps and generalize to Hilbert C*-modules the Naimark-Sz-Nagy characterization of positive definite functions on groups [J.Heo, J.Math.Anal.Appl., 2007]. In the last part of the paper it is given the dilation theory obtained in [G.J. Murphy, Proc. Amer. Math.Soc., 1997] in the case of unitary operator-valued multipliers [Un Cig Ji, Young Yi Kim and Su Hyung Park, J. Math. Anal. Appl., 2007].

  14. One Point Isometric Matching with the Heat Kernel

    KAUST Repository

    Ovsjanikov, Maks

    2010-09-21

    A common operation in many geometry processing algorithms consists of finding correspondences between pairs of shapes by finding structure-preserving maps between them. A particularly useful case of such maps is isometries, which preserve geodesic distances between points on each shape. Although several algorithms have been proposed to find approximately isometric maps between a pair of shapes, the structure of the space of isometries is not well understood. In this paper, we show that under mild genericity conditions, a single correspondence can be used to recover an isometry defined on entire shapes, and thus the space of all isometries can be parameterized by one correspondence between a pair of points. Perhaps surprisingly, this result is general, and does not depend on the dimensionality or the genus, and is valid for compact manifolds in any dimension. Moreover, we show that both the initial correspondence and the isometry can be recovered efficiently in practice. This allows us to devise an algorithm to find intrinsic symmetries of shapes, match shapes undergoing isometric deformations, as well as match partial and incomplete models efficiently. Journal compilation © 2010 The Eurographics Association and Blackwell Publishing Ltd.

  15. MEG Insight into the Spectral Dynamics Underlying Steady Isometric Muscle Contraction

    Science.gov (United States)

    Piitulainen, Harri; Zhou, Guangyu

    2017-01-01

    To gain fundamental knowledge on how the brain controls motor actions, we studied in detail the interplay between MEG signals from the primary sensorimotor (SM1) cortex and the contraction force of 17 healthy adult humans (7 females, 10 males). SM1 activity was coherent at ∼20 Hz with surface electromyogram (as already extensively reported) but also with contraction force. In both cases, the effective coupling was dominant in the efferent direction. Across subjects, the level of ∼20 Hz coherence between cortex and periphery positively correlated with the “burstiness” of ∼20 Hz SM1 (Pearson r ≈ 0.65) and peripheral fluctuations (r ≈ 0.9). Thus, ∼20 Hz coherence between cortex and periphery is tightly linked to the presence of ∼20 Hz bursts in SM1 and peripheral activity. However, the very high correlation with peripheral fluctuations suggests that the periphery is the limiting factor. At frequencies signals and ∼20 Hz SM1 envelope were coherent with both force and its absolute change rate. The effective coupling dominated in the efferent direction between (1) force and the ∼20 Hz SM1 envelope and (2) the absolute change rate of the force and SM1 signals. Together, our data favor the view that ∼20 Hz coherence between cortex and periphery during isometric contraction builds on the presence of ∼20 Hz SM1 oscillations and needs not rely on feedback from the periphery. They also suggest that effective cortical proprioceptive processing operates at <3 Hz frequencies, even during steady isometric contractions. SIGNIFICANCE STATEMENT Accurate motor actions are made possible by continuous communication between the cortex and spinal motoneurons, but the neurophysiological basis of this communication is poorly understood. Using MEG recordings in humans maintaining steady isometric muscle contractions, we found evidence that the cortex sends population-level motor commands that tend to structure according to the ∼20 Hz sensorimotor rhythm, and that

  16. Whole body oxygen uptake and evoked torque during subtetanic isometric electrical stimulation of the quadriceps muscles in a single 30-minute session.

    Science.gov (United States)

    Minogue, Conor M; Caulfield, Brian M; Lowery, Madeleine M

    2014-09-01

    To evaluate the time course of fatigue in torque output and oxygen uptake during isometric subtetanic neuromuscular electrical stimulation (NMES) to facilitate the design of NMES-based rehabilitation protocols that can accumulate a defined aerobic exercise volume within a given time period. Single-arm intervention study with within-subject comparisons. University research laboratory. Volunteer sample of healthy men (N=11; mean age, 34.2 ± 11.5 y; range, 19-53 y; body mass, 79.1 ± 11.7 kg; range, 58-100 kg). A single 30-minute session of continuous bilateral isometric quadriceps NMES at 4 Hz evoking a mean twitch amplitude of 12% of the maximum voluntary contraction. Whole body oxygen consumption rate (V˙o2), and evoked torque were measured simultaneously throughout. Mean increment in V˙o2 was 596 ± 238 mL/min, and average exercise intensity during the session was 3 ±.47 metabolic equivalents. The V˙o2 and torque declined slowly at a rate of -.54%±.31% and -.47%±.57% per minute, respectively. Despite having a higher incremental V˙o2, the observed fatigue rate was considerably less than that previously reported during intermittent isometric tetanic stimulation, suggesting that subtetanic isometric NMES is more sustainable for exercise interventions aimed at accumulating a therapeutic aerobic exercise volume. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  17. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting

    OpenAIRE

    Singh, Rabindarjeet; Hwa, Ooi Cheong; Roy, Jolly; Jin, Chai Wen; Ismail, Siti Musyrifah; Lan, Mohamad Faizal; Hiong, Loo Lean; Aziz, Abdul-Rashid

    2011-01-01

    Purpose To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month. Methods Seven hundred and thirty-four (411 male and 323 female) Malaysian Junior-level Muslim athletes (mean age 16.3 ± 2.6 y) participated in the survey which was designed to establish the personal perception of their sport performance, sleep pattern, food and fluid intake during Ramadan fasting. The survey was conducted ...

  18. Performance Gaps between Online and Face-to-Face Courses: Differences across Types of Students and Academic Subject Areas

    Science.gov (United States)

    Xu, Di; Jaggars, Shanna S.

    2014-01-01

    Using a dataset containing nearly 500,000 courses taken by over 40,000 community and technical college students in Washington State, this study examines the performance gap between online and face-to-face courses and how the size of that gap differs across student subgroups and academic subject areas. While all types of students in the study…

  19. An examination of lower limb asymmetry in ankle isometric force control.

    Science.gov (United States)

    Yen, Sheng-Che; Olsavsky, Laura C; Cloonan, Caitlin M; Llanos, Amelia R; Dwyer, Kara J; Nabian, Mohsen; Farjadian, Amir Bahador

    2017-11-11

    While asymmetries have been observed between the dominant and non-dominant legs, it is unclear whether they have different abilities in isometric force control (IFC). The purpose of this study was to compare ankle IFC between the legs. IFC is important for stabilization rather than object manipulation, and people typically use their non-dominant leg for stabilization tasks. Additionally, studies suggested that a limb can better acquire a motor task when the control mechanism of the task is related to what the limb is specialized for. We hypothesized that the non-dominant leg would better (1) control ankle IFC with speed and accuracy, and (2) acquire an ankle IFC skill through direct learning and transfer of learning. Two participant groups practiced an IFC task using either their dominant or non-dominant ankle. In a virtual environment, subjects moved a cursor to hit 24 targets in a maze by adjusting the direction and magnitude of ankle isometric force with speed (measured by the time required to hit all targets or movement time) and accuracy (number of collisions to a maze wall). Both groups demonstrated similar movement time and accuracy between the dominant and non-dominant limbs before practicing the task. After practice, both groups showed improvement in both variables on both the practiced and non-practiced sides (p < .01), but no between-group difference was detected in the degree of improvement on each side. The ability to control and acquire the IFC skill was similar between the legs, which did not support the brain is lateralized for ankle IFC. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. The influence of isometric preload on power expressed during bench press in strength-trained men.

    Science.gov (United States)

    Bartolomei, Sandro; Fukuda, David H; Hoffman, Jay R; Stout, Jeffrey R; Merni, Franco

    2017-03-01

    The purpose of this study was to compare the power expressed during the bench press exercise in resistance-trained men following different pre-activation conditions. Twenty-two trained men (age 24.1 ± 1.7 years, height 178.6 ± 6.1 cm, body mass 81.1 ± 10.6 kg) completed a maximal effort bench press (1-RM) test (100.0 kg ± 8.1 kg). In a subsequent assessment, each participant performed concentric bench press movements with loads of 20%, 30%, 40% and 50% of their 1-RM preceded by either a concentric contraction (CC), a low isometric preload (LIP; 70% 1-RM) or a high isometric preload (HIP; 100% 1-RM) conditions. All movements were performed in a Smith machine with a settable quick-release device. Participants performed all three conditions in randomized fashion. Results indicated that power outputs during the bench press exercise following HIP were significantly (p < 0.05) greater than CC at 20% 1-RM (+9%), 30% 1-RM (+16%) and 40% 1-RM (+14%), and LIP at 20% 1-RM (+4%), 30% 1-RM (+20%) and 40% 1-RM (+15%). No differences were found between conditions at 50% 1-RM. Area under the force-power curve with HIP was greater (p < 0.05) than with CC and LIP. In conclusion, results of this study indicate that the use of a HIP (100% 1-RM) in trained participants results in significantly greater power output during the concentric phase of a multi-joint exercise when compared to standard concentric movement.

  1. Subjective Estimates of Job Performance after Job Preview: Determinants of Anticipated Learning Curves

    Science.gov (United States)

    Ackerman, Phillip L.; Shapiro, Stacey; Beier, Margaret E.

    2011-01-01

    When people choose a particular occupation, they presumably make an implicit judgment that they will perform well on a job at some point in the future, typically after extensive education and/or on-the-job experience. Research on learning and skill acquisition has pointed to a power law of practice, where large gains in performance come early in…

  2. RCT - subjective physical performance and quality of life after a 6-month programmed sports therapy (PST) in patients with haemophilia.

    Science.gov (United States)

    Runkel, B; Von Mackensen, S; Hilberg, T

    2017-01-01

    Musculoskeletal bleedings lead to limitations in the locomotor system and consequently, in health-related quality of life (HRQoL) in patients with haemophilia (PwH). Sports therapy is increasingly recommended to improve their physical performance. Until today, randomised controlled studies investigating changes in physical performance in PwH are rare. This study investigates the impact of programmed sports therapy on the subjective physical performance and the HRQoL in PwH. A randomised controlled trial (RCT) was conducted with a training intervention for over 6 months. For this purpose, 64 PwH with moderate (n = 5) or severe (n = 59) haemophilia A (n = 57) or B (n = 7) were randomised into two groups - intervention (IG) or control group (CG). The HRQoL was assessed with the SF-36 questionnaire and the disease-specific Haem-A-QoL before and after the intervention. The subjective physical performance was tested by the HEP-Test-Q. After the 6-month training intervention, PwH in the IG subjectively reported significant better 'endurance' (P = 0.000) in the HEP-Test-Q compared to the CG. In the SF-36, a significant difference in the domains 'general health perceptions' (P = 0.005) and 'mental health' (P = 0.001) was detected. The haemophilia-specific HRQoL questionnaire showed a significant improvement in the dimensions 'feeling' (P = 0.049), 'work' (P = 0.046) and 'family' (P = 0.040). In the first RCT evaluating the impact of a 6-month training intervention on the subjective perception of PwH, an increase in subjective physical performance and some domains of HRQoL was demonstrated in the IG. Specific sports therapy should be included into the comprehensive treatment under supervision and monitoring by experienced staff. © 2016 John Wiley & Sons Ltd.

  3. Performance of Pre-Stressed Sandwich Composites Subjected to Shock Wave Loading

    Directory of Open Access Journals (Sweden)

    Shukla A.

    2010-06-01

    Full Text Available The present paper experimentally studies the dynamic behaviour of prestressed sandwich composites under blast loading. The in-plane static compression loadings are implemented on the sandwich composites before they are subjected to the transverse shock wave loading. Three different pre-stress levels are chosen. 3-D realtime deformation data are captured by two high-speed photography systems: a backview Digital Image Correlation (DIC system and a side-view camera system. The results show that pre-stresses can induce local buckling in the front face-sheet of sandwich composites, consequently reduce the blast resistance of sandwich composites.

  4. Acute response to a 2-minute isometric exercise test predicts the blood pressure-lowering efficacy of isometric resistance training in young adults

    OpenAIRE

    Somani, Yasina B.; Baross, Anthony W.; Brook, Robert D.; Milne, Kevin J.; McGowan, Cheri L.; Swaine, Ian L.

    2017-01-01

    Background:\\ud \\ud This work aimed to explore whether different forms of a simple isometric exercise test could be used to predict the blood pressure (BP)-lowering efficacy of different types of isometric resistance training (IRT) in healthy young adults. In light of the emphasis on primary prevention of hypertension, identifying those with normal BP who will respond to IRT is important. Also, heightened BP reactivity increases hypertension risk, and as IRT reduces BP reactivity in patients w...

  5. Isometric yoga improves the fatigue and pain of patients with chronic fatigue syndrome who are resistant to conventional therapy: a randomized, controlled trial.

    Science.gov (United States)

    Oka, Takakazu; Tanahashi, Tokusei; Chijiwa, Takeharu; Lkhagvasuren, Battuvshin; Sudo, Nobuyuki; Oka, Kae

    2014-01-01

    Patients with chronic fatigue syndrome (CFS) often complain of persistent fatigue even after conventional therapies such as pharmacotherapy, cognitive behavioral therapy, or graded exercise therapy. The aim of this study was to investigate in a randomized, controlled trial the feasibility and efficacy of isometric yoga in patients with CFS who are resistant to conventional treatments. This trial enrolled 30 patients with CFS who did not have satisfactory improvement after receiving conventional therapy for at least six months. They were randomly divided into two groups and were treated with either conventional pharmacotherapy (control group, n = 15) or conventional therapy together with isometric yoga practice that consisted of biweekly, 20-minute sessions with a yoga instructor and daily in-home sessions (yoga group, n = 15) for approximately two months. The short-term effect of isometric yoga on fatigue was assessed by administration of the Profile of Mood Status (POMS) questionnaire immediately before and after the final 20-minute session with the instructor. The long-term effect of isometric yoga on fatigue was assessed by administration of the Chalder's Fatigue Scale (FS) questionnaire to both groups before and after the intervention. Adverse events and changes in subjective symptoms were recorded for subjects in the yoga group. All subjects completed the intervention. The mean POMS fatigue score decreased significantly (from 21.9 ± 7.7 to 13.8 ± 6.7, P fatigue, two patients with CFS and fibromyalgia syndrome in the yoga group also reported pain relief. Furthermore, many subjects reported that their bodies became warmer and lighter after practicing isometric yoga. Although there were no serious adverse events in the yoga group, two patients complained of tiredness and one of dizziness after the first yoga session with the instructor. Isometric yoga as an add-on therapy is both feasible and successful at relieving the fatigue and pain of a

  6. The Mulligan ankle taping does not affect balance performance in healthy subjects: a prospective, randomized blinded trial.

    Science.gov (United States)

    de-la-Morena, Jose Maria Delfa; Alguacil-Diego, Isabel Maria; Molina-Rueda, Francisco; Ramiro-González, Maria; Villafañe, Jorge Hugo; Fernández-Carnero, Josué

    2015-05-01

    [Purpose] The aim of this study was to evaluate the immediate effects of Mulligan fibular taping on static and dynamic postural balance in healthy subjects using computerized dynamic posturography (CDP). [Subjects and Methods] Forty-four volunteers (26 males and 18 females) aged 21 ±2 years participated in the study. The Mulligan tape was applied by a specialist in this technique. The placebo group received a treatment with a similar tape but with several cuts to avoid the fibular repositioning effect produced by Mulligan tape. The Sensory Organization Test (SOT) and the Motor Control Test (MCT) were performed by each subject at baseline and after the interventions. Outcome measures included equilibrium and strategy scores from each trial and condition of the SOT, and speed of reaction (latency period) from the MCT. [Results] Mulligan ankle taping did not have an impact on postural control during static and dynamic balance in subjects with healthy ankles when compared with placebo taping. [Conclusion] There was no difference in, equilibrium and strategy (SOT) and speed of reaction (MCT) in any of the subjects in this study. Therefore, this study suggests that Mulligan ankle taping does not have an impact on balance in healthy subjects.

  7. Concept mapping improves academic performance in problem solving questions in biochemistry subject

    National Research Council Canada - National Science Library

    Baig, Mukhtiar; Tariq, Saba; Rehman, Rehana; Ali, Sobia; Gazzaz, Zohair J

    2016-01-01

    To assess the effectiveness of concept mapping (CM) on the academic performance of medical students' in problem-solving as well as in declarative knowledge questions and their perception regarding CM...

  8. Effects of Sleep Hygiene Education on Subjective Sleep Quality and Academic Performance

    National Research Council Canada - National Science Library

    Şahin, Erkan Melih

    .... It is known that sleep quality and daytime sleepiness cause decrasing academic performans. For this reason we aimed to investigate the effects of a sleep hygiene education on sleep quality and academic performance of first year medical students...

  9. Relationship between ACE-DD polymorphism and diastolic performance in healthy subjects.

    Science.gov (United States)

    Di Pasquale, Pietro; Cannizzaro, Sergio; Scalzo, Sebastiano; Giubilato, Alfonso; Maringhini, Giorgio; Giambanco, Francesco; Sarullo, Filippo; Tarsia, Giandomenico; Giammanco, Marco; Gaspare, Parrinello; Paterna, Salvatore

    2004-05-01

    The ACE-D allele has been associated with cardiovascular disease. The study evaluates the relationship between the ACE-ID genotypes and diastolic function in healthy subjects after 6 years of follow-up. Two hundred and seventy-five healthy volunteers aged 25-55 years had normal physical examination, 12-lead ECG, acceptable echocardiographic windows and echocardiogram at entry. Venous blood was drawn for DNA analysis. Two hundred and forty-two subjects completed 6 years of follow-up. Three genetically distinct groups were obtained: ACE-DD group (n=71, 26F/45M, mean age 48 +/- 7 years); ACE-ID (n=115, 39F/76M, mean age 40 +/- 7 years); and ACE-II (n=56, 20F/36M, mean age 47 +/- 6 years). Significant differences in E/A ratio were found between ACE-DD and ACE-ID, and ACE II (p=0.028, <0.0001, 0.0001), respectively. After 6 years, echocardiography showed a significant reduction of E/A ratio in the ACE-DD group, p=0.0001. The data suggest that ACE-DD is associated with deteriorating myocardial diastolic properties.

  10. The isometric torque at which knee-extensor muscle reoxygenation stops.

    NARCIS (Netherlands)

    de Ruiter, C.J.; Goudsmit, J.F.; Tricht, J.A.; de Haan, A.

    2007-01-01

    PURPOSE: We investigated the knee-extensor torque at which reoxygenation (inflow of arterial blood) during an isometric contraction stopped, whether this torque depended on maximal torque capacity (MTC), and whether there were differences among the synergists. METHODS: Isometric knee-extension

  11. Sub-sarcolemmal swelling of sarcoplasmic reticulum after isometric contractions in rat semimembranosus lateralis muscle

    NARCIS (Netherlands)

    Willems, M.E.T.; Huijing, P.A.J.B.M.; Friden, J.

    1999-01-01

    The decline in isometric force, swelling of sarcoplasmic reticulum and loss of desmin was measured in semimembranosus lateralis muscle of male Wistar rats immediately after a short series of brief (500 ms) maximal isometric contractions. For the active muscle, the series ended below (protocol A) and

  12. Relation of eye dominancy with color vision discrimination performance ability in normal subjects

    Directory of Open Access Journals (Sweden)

    Belkıs Koçtekin

    2013-10-01

    Full Text Available AIM: To evaluate the performance of dominant eye (DE for color vision discrimination ability among the medical students with normal color vision.CONCLUSION: The color vision discrimination performance ability was found prominent for DE. This superiority was attributed to higher sensitivityof the r/g local color spectral region. We conclude that DE has priority in r/g color spectral region, probably including inhibition of NDE.

  13. Effects of Sleep Hygiene Education on Subjective Sleep Quality and Academic Performance

    OpenAIRE

    Erkan Sahin

    2014-01-01

    Aim: Sleep problems are common in students with one third of university students reporting insufficient sleep. It is known that sleep quality and daytime sleepiness cause decrasing academic performans. For this reason we aimed to investigate the effects of a sleep hygiene education on sleep quality and academic performance of first year medical students. Material and Method: Self-reported sleep data and academic performance of 131 first grade medical students were collected. To all students e...

  14. Flupentixolhydrochloride in low dosages: effects on perceptual and psychomotor performance in emotionally stable and emotionally labile healthy subjects.

    Science.gov (United States)

    Rösler, F; Stieglitz, R D; Manzey, D

    1986-01-01

    Effects of flupentixol on performance were evaluated in a double-blind study with 107 healthy male subjects. Experimental factors were dosage (0, 1, and 2 mg Fluanxol 0.5/day), the trait variable 'neuroticism' (high vs. low score on a questionnaire scale), and time of measurement (before and after 4 days of treatment). Drug effects were measured by means of seven paper-and-pencil tests and eight apparatus tests covering the following cognitive functions: endurance in attention, spacial orientation, flexibility and speed of closure, perceptual speed, response speed, psychomotor coordination, knowledge of traffic rules, and basic motoric tempo. Univariate and multivariate ANOVAs disclosed that flupentixol has detrimental effects on perceptual and psychomotor functions, in particular when administered in a dosage of 2 mg/day. These treatment effects did not interact with the trait variable neuroticism. Nevertheless, there were substantial differences between emotionally stable and emotionally labile subjects in both absolute performance level and change of performance over time.

  15. Mismatch negativity and cognitive performance for the prediction of psychosis in subjects with at-risk mental state.

    Directory of Open Access Journals (Sweden)

    Yuko Higuchi

    Full Text Available BACKGROUND: A shorter duration of untreated psychosis has been associated with better prognosis in schizophrenia. In this study, we measured the duration mismatch negativity (dMMN, an event-related potential, and cognitive performance in subjects with at-risk mental state (ARMS, patients with first-episode or chronic schizophrenia, and healthy volunteers. The main interest was to determine if these neurocognitive measures predict progression to overt schizophrenia in ARMS subjects. METHODOLOGY/PRINCIPAL FINDINGS: Seventeen ARMS subjects, meeting the criteria of the Comprehensive Assessment of At-Risk Mental State, 31 schizophrenia patients (20 first-episode and 11 chronic and healthy controls (N=20 participated in the study. dMMN was measured by an auditory odd-ball paradigm at baseline. Neuropsychological performance was evaluated by the Japanese version of the Brief assessment of cognitive function of schizophrenia (BACS-J. The first-episode schizophrenia group showed significantly smaller amplitudes at frontal electrodes than did control subjects whereas chronic patients elicited smaller amplitudes at frontal and central electrodes, consistent with previous reports. During the follow-up period, 4 out of the 17 ARMS subjects transitioned to schizophrenia (converters while 13 did not (non-converters. Specifically, dMMN amplitudes of non-converters did not differ from those of healthy controls, while converters showed significantly smaller dMMN amplitudes at some electrodes compared to control subjects. Converters performed significantly worse on tests of working memory, verbal fluency, and attention/information processing than did non-converters. There was a significant positive correlation between dMMN amplitudes at the frontal electrodes and verbal fluency, as measured by the BACS, in the AMRS subjects as a whole. CONCLUSIONS/SIGNIFICANCE: ARMS subjects who later developed schizophrenia elicited smaller dMMN amplitudes to begin with, compared

  16. Comparison of the pedalling performance induced by magnetic and electrical stimulation cycle ergometry in able-bodied subjects.

    Science.gov (United States)

    Szecsi, J; Straube, A; Fornusek, C

    2014-04-01

    The purpose of the study was to compare the mechanical power and work generated by able-bodied subjects during functional magnetic stimulation (FMS) vs. functional electrical stimulation (FES) induced ergometer training conditions. Both stimulation methods were applied at a 30 Hz frequency to the quadriceps muscles of 22 healthy able-bodied subjects to induce cycling for 4× four minutes or until exhaustion. FMS was performed via large surface, cooled coils, while FES was applied with a typical stimulation setup used for cycling. Significantly more (pstimulation induced pain and fatigue mechanisms of the neuromuscular system. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

  17. Can a multimedia tool help students' learning performance in complex biology subjects?

    Directory of Open Access Journals (Sweden)

    Pinar Koseoglu

    2015-11-01

    Full Text Available The aim of the present study was to determine the effects of multimedia-based biology teaching (Mbio and teacher-centered biology (TCbio instruction approaches on learners' biology achievements, as well as their views towards learning approaches. During the research process, an experimental design with two groups, TCbio (n = 22 and Mbio (n = 26, were used. The results of the study proved that the Mbio approach was more effective than the TCbio approach with regard to supporting meaningful learning, academic achievement, enjoyment and motivation. Moreover, the TCbio approach is ineffective in terms of time management, engaging attention, and the need for repetition of subjects. Additionally, the results were discussed in terms of teaching, learning, multimedia design as well as biology teaching/learning.

  18. Performances on simulator and da Vinci robot on subjects with and without surgical background.

    Science.gov (United States)

    Moglia, Andrea; Ferrari, Vincenzo; Melfi, Franca; Ferrari, Mauro; Mosca, Franco; Cuschieri, Alfred; Morelli, Luca

    2017-08-17

    To assess whether previous training in surgery influences performance on da Vinci Skills Simulator and da Vinci robot. In this prospective study, thirty-seven participants (11 medical students, 17 residents, and 9 attending surgeons) without previous experience in laparoscopy and robotic surgery performed 26 exercises at da Vinci Skills Simulator. Thirty-five then executed a suture using a da Vinci robot. The overall scores on the exercises at the da Vinci Skills Simulator show a similar performance among the groups with no statistically significant pair-wise differences (p robotic surgery, insignificant differences in the scores at the da Vinci Skills Simulator and at the da Vinci robot on inanimate models.

  19. Cultural performances: the zombie invasion, the death of the subject and other disorientation

    Directory of Open Access Journals (Sweden)

    Sainy C.B. Veloso

    2013-06-01

    Full Text Available The article considers how contemporary cultural performances indicial, the worldwide proliferation of fictional theme of the zombie apocalypse, through comic books, board games, movies, games, television serials, posters, rallies. Since then, reflects the theme and looks at this set of products and actions, limited the issue: the current crisis is a crisis of guidance within a world not interpretable, as demonstrates the zombie invasion? To this end, rests on concepts of cultural performances delimiters (GOFFMAN, 2011; social drama (TURNER, 1974; culture (GEERTZ, 1989; and social crisis (JAMESON, 1997; SENNETT, 1998.

  20. [ISOMETRIC RETRACTION AND THE INVISIBLE PROCESSES OF NERVE CELLS].

    Science.gov (United States)

    Sotnikov, O S; Vasyagina, N Yu; Krasnova, T V

    2015-01-01

    Recently, a large number of physiological studies on stress and hibernation had described an unusual morphological phenomenon of the rapid disappearance and reapperance of apical dendrites of pyramidal neurons of the hippocampus, prefrontal cortex and other parts of the brain. In this article an attempt is maid to explain this phenomenon on the basis of morphological analysis of natural elastic properties of neuroplasm and structural kinetics of partially preserved processes of the living isolated neurons. The neuroplasm displacement with its bidirectional flow was identified in the processes. A new physiological phenomenon is described--the isometric retraction of nerve cell processes, during which the neuroplasm fluxes were directed to the opposite sides, leading to abrupt thinning of middle parts of the processes and to a thickening of both ends. It is suggested that the extremely attenuated processes can reach the submicroscopic sizes, becoming invisible in the light microscope. The repeated reversible "disappearance" and "appearance" of the processes was demonstrated supravitally in the culture of neurons and of C-1300 neuroblastoma cells. Reduction of the diameter of the processes to a limit of their visibility was demonstrated by the example of their natural stretching. The same effect was observed in the areas between the reversible varicosities of the processes. These areas became extremely thin, and then invisible. Becoming thinner, the processes were capable of sharp extension. A review of the available literature and our own data allow to conclude that the phenomenon of the disappearance of the apical dendrites was due to their isometric retraction, which lead to the emergence of "invisible processes".

  1. Validation of a novel automatic sleep spindle detector with high performance during sleep in middle aged subjects

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Christensen, Julie A. E.; Kempfner, Jacob

    2012-01-01

    Many of the automatic sleep spindle detectors currently used to analyze sleep EEG are either validated on young subjects or not validated thoroughly. The purpose of this study is to develop and validate a fast and reliable sleep spindle detector with high performance in middle aged subjects....... An automatic sleep spindle detector using a bandpass filtering approach and a time varying threshold was developed. The validation was done on sleep epochs from EEG recordings with manually scored sleep spindles from 13 healthy subjects with a mean age of 57.9 ± 9.7 years. The sleep spindle detector reached...... a mean sensitivity of 84.6 % and a mean specificity of 95.3 %. The sleep spindle detector can be used to obtain measures of spindle count and density together with quantitative measures such as the mean spindle frequency, mean spindle amplitude, and mean spindle duration....

  2. Structural Performance of a Hybrid FRP-Aluminum Modular Triangular Truss System Subjected to Various Loading Conditions

    Directory of Open Access Journals (Sweden)

    Dongdong Zhang

    2014-01-01

    Full Text Available A novel hybrid FRP-aluminum truss system has been employed in a two-rut modular bridge superstructure composed of twin inverted triangular trusses. The actual flexural behavior of a one-rut truss has been previously investigated under the on-axis loading test; however, the structural performance of the one-rut truss subjected to an off-axis load is still not fully understood. In this paper, a geometrical linear finite element model is introduced and validated by the on-axis loading test; the structural performance of the one-rut truss subjected to off-axis load was numerically obtained; the dissimilarities of the structural performance between the two different loading cases are investigated in detail. The results indicated that (1 the structural behavior of the off-axis load differs from that of the on-axis load, and the off-axis load is the critical loading condition controlling the structural performance of the triangular truss; (2 under the off-axis load, the FRP trussed members and connectors bear certain out-of-plane bending moments and are subjected to a complicated stress state; and (3 the stress state of these members does not match that of the initial design, and optimization for the redesign of these members is needed, especially for the pretightened teeth connectors.

  3. A within-subjects comparison of learning and memory performance before and after cardiac catheterization.

    NARCIS (Netherlands)

    Verwey, B.; Derikx, R.L.; Waarde, J.A. van; Essink, G.; Rooij, I.A.L.M. van; Zitman, F.G.

    2007-01-01

    OBJECTIVE: To investigate the influence of stress on the recall of neutral information in a clinical setting, a prospective study was performed on patients who were admitted to the hospital for cardiac catheterization. METHODS: During their hospital stay, 39 cardiac patients were tested for verbal

  4. Clearing the air : The effect of experimenter race on target's test performance and subjective experience

    NARCIS (Netherlands)

    Marx, DM; Goff, PA

    2005-01-01

    According to stereotype threat theory (Steele, 1997), stereotyped targets under-perform on challenging tests, in part because they are worried about being viewed in terms of the negative stereotype that they are intellectually inferior. How then are the negative effects of stereotype threat reduced

  5. Executive Functions in Older Adults With Autism Spectrum Disorder : Objective Performance and Subjective Complaints

    NARCIS (Netherlands)

    Davids, Roeliena C. D.; Groen, Yvonne; Berg, Ina J.; Tucha, Oliver M.; van Balkom, Ingrid D. C.

    Although deficits in Executive Functioning (EF) are reported frequently in young individuals with Autism Spectrum Disorders (ASD), they remain relatively unexplored later in life (> 50 years). We studied objective performance on EF measures (Tower of London, Zoo map, phonetic/semantic fluency) as

  6. International Differences in Subjective Performance Evaluation, Compensation and Career Dynamics in a Global Company

    DEFF Research Database (Denmark)

    Halse, Nikolaj; Smeets, Valerie Anne Rolande; Warzynski, Frederic Michel Patrick

    .S. and Asia (Japan and China). We try to understand why performance evaluation is distributed differently across countries, and how these differences affect wage growth, the size of the bonus and promotion decisions. We find that evaluations tend to be better on average at the headquarter, but also that wages...

  7. First year medical students' learning style preferences and their correlation with performance in different subjects within the medical course.

    Science.gov (United States)

    Hernández-Torrano, Daniel; Ali, Syed; Chan, Chee-Kai

    2017-08-08

    Students commencing their medical training arrive with different educational backgrounds and a diverse range of learning experiences. Consequently, students would have developed preferred approaches to acquiring and processing information or learning style preferences. Understanding first-year students' learning style preferences is important to success in learning. However, little is understood about how learning styles impact learning and performance across different subjects within the medical curriculum. Greater understanding of the relationship between students' learning style preferences and academic performance in specific medical subjects would be valuable. This cross-sectional study examined the learning style preferences of first-year medical students and how they differ across gender. This research also analyzed the effect of learning styles on academic performance across different subjects within a medical education program in a Central Asian university. A total of 52 students (57.7% females) from two batches of first-year medical school completed the Index of Learning Styles Questionnaire, which measures four dimensions of learning styles: sensing-intuitive; visual-verbal; active-reflective; sequential-global. First-year medical students reported preferences for visual (80.8%) and sequential (60.5%) learning styles, suggesting that these students preferred to learn through demonstrations and diagrams and in a linear and sequential way. Our results indicate that male medical students have higher preference for visual learning style over verbal, while females seemed to have a higher preference for sequential learning style over global. Significant associations were found between sensing-intuitive learning styles and performance in Genetics [β = -0.46, B = -0.44, p styles and performance in Genetics [β = 0.36, B = 0.43, p learning techniques. Instructors can also benefit by modifying and adapting more appropriate teaching approaches in these

  8. The prefrontal model revisited: double dissociations between young sleep deprived and elderly subjects on cognitive components of performance.

    Science.gov (United States)

    Tucker, Adrienne M; Stern, Yaakov; Basner, Robert C; Rakitin, Brian C

    2011-08-01

    The prefrontal model suggests that total sleep deprivation (TSD) and healthy aging produce parallel cognitive deficits. Here we decompose global performance on two common tasks into component measures of specific cognitive processes to pinpoint the source of impairments in elderly and young TSD participants relative to young controls and to each other. The delayed letter recognition task (DLR) was performed in 3 studies. The psychomotor vigilance task (PVT) was performed in 1 of the DLR studies and 2 additional studies. For DLR, young TSD (n=20, age=24.60 ± 0.62 years) and young control (n=17, age=24.00 ± 2.42); elderly (n=26, age=69.92 ± 1.06). For the PVT, young TSD (n=18, age=26.65 ± 4.57) and young control (n=16, age=25.19 ± 2.90); elderly (n=21, age=71.1 ± 4.92). Both elderly and young TSD subjects displayed impaired reaction time (RT), our measure of global performance, on both tasks relative to young controls. After decomposing global performance on the DLR, however, a double dissociation was observed as working memory scanning speed was impaired only in elderly subjects while other components of performance were impaired only by TSD. Similarly, for the PVT a second double dissociation was observed as vigilance impairments were present only in TSD while short-term response preparation effects were altered only in the elderly. The similarity between TSD and the elderly in impaired performance was evident only when examining global RT. In contrast, when specific cognitive components were examined double dissociations were observed between TSD and elderly subjects. This demonstrates the heterogeneity in those cognitive processes impaired in TSD versus the elderly.

  9. The impact of sleep duration and subject intelligence on declarative and motor memory performance: how much is enough?

    Science.gov (United States)

    Tucker, Matthew A; Fishbein, William

    2009-09-01

    Recent findings clearly demonstrate that daytime naps impart substantial memory benefits compared with equivalent periods of wakefulness. Using a declarative paired associates task and a procedural motor sequence task, this study examined the effect of two lengthier durations of nocturnal sleep [either a half night (3.5 h) or a full night (7.5 h) of sleep] on over-sleep changes in memory performance. We also assessed whether subject intelligence is associated with heightened task acquisition and, more importantly, whether greater intelligence translates to greater over-sleep declarative and procedural memory enhancement. Across both tasks, we demonstrate that postsleep performance gains are nearly equivalent, regardless of whether subjects obtain a half night or a full night of sleep. Remarkably, the over-sleep memory changes observed on both tasks are very similar to findings from studies examining performance following a daytime nap. Consistent with previous research, we also observed a strong positive correlation between amount of Stage 2 sleep and motor skill performance in the full-night sleep group. This finding contrasts with a highly significant correlation between spectral power in the spindle frequency band (12-15 Hz) and motor skill enhancement only in the half-night group, suggesting that sigma power and amount of Stage 2 sleep are both important for optimal motor memory processing. While subject intelligence correlated positively with acquisition and retest performance on both tasks, it did not correlate with over-sleep changes in performance on either task, suggesting that intelligence may not be a powerful modulator of sleep's effect on memory performance.

  10. Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox.

    Science.gov (United States)

    Germonpré, Peter; Balestra, Costantino; Hemelryck, Walter; Buzzacott, Peter; Lafère, Pierre

    2017-05-01

    Divers try to limit risks associated with their sport, for instance by breathing enriched air nitrox (EANx) instead of air. This double blinded, randomized trial was designed to see if the use of EANx could effectively improve cognitive performance while diving. Eight volunteers performed two no-decompression dry dives breathing air or EANx for 20 min at 0.4 MPa. Cognitive functions were assessed with a computerized test battery, including MathProc and Ptrail. Measurements were taken before the dive, upon arrival and after 15 min at depth, upon surfacing, and at 30 min postdive. After each dive subjects were asked to identify the gas they had just breathed. Identification of the breathing gas was not possible on subjective assessment alone, while cognitive assessments showed significantly better performance while breathing EANx. Before the dives, breathing air, mean time to complete the task was 1795 ms for MathProc and 1905 ms for Ptrail. When arriving at depth MathProc took 1616 ms on air and 1523 ms on EANx, and Ptrail took 1318 ms on air and and 1356 ms on EANx, followed 15 min later by significant performance inhibition while breathing air during the ascent and the postdive phase, supporting the concept of late dive/postdive impairment. The results suggest that EANx could protect against decreased neuro-cognitive performance induced by inert gas narcosis. It was not possible for blinded divers to identify which gas they were breathing and differences in postdive fatigue between air and EANx diving deserve further investigation.Germonpré P, Balestra C, Hemelryck W, Buzzacott P, Lafère P. Objective vs. subjective evaluation of cognitive performance during 0.4-MPa dives breathing air or nitrox. Aerosp Med Hum Perform. 2017; 88(5):469-475.

  11. Comparative effects of proprioceptive and isometric exercises on pain intensity and difficulty in patients with knee osteoarthritis: A randomised control study.

    Science.gov (United States)

    Ojoawo, Adesola O; Olaogun, Matthew O B; Hassan, Mariam A

    2016-11-14

    The study compared the effects of isometric quadriceps exercise and proprioceptive exercise on pain, joint stiffness and physical difficulties of patients with knee osteoarthritis. Forty-five patients with history of knee osteoarthritis were randomly allocated into two groups; A with 23 subjects and B with 22 subjects. All subjects received infrared radiation for 20 minutes and kneading massage with methyl salicylate ointment. Group A underwent proprioceptive exercises while Group B had isometric quadriceps exercise. Each exercise session lasted for 10 minutes according to standard protocol, twice in a week for six weeks. Pre-treatment, 3rd week and 6th week pain intensity, joint stiffness and physical difficulties were assessed using Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. Statistical package for social sciences (SPSS) version 17 was used to analyse the data while descriptive and inferential statistics were used to summarise the result. Proprioceptive exercises reduced pain intensity significantly (F = 4.76; p = 0.00) at 6th week with effect size of 2.79, and physical difficulty (F = 3.69; p exercises. There was a significant reduction in the pain intensity (F = 12.08; p exercises are effective but proprioceptive exercises may be more effective in the management of patients with knee osteoarthritis (KOA) than isometric exercises.

  12. It matters how old you feel: Antecedents and performance consequences of average relative subjective age in organizations.

    Science.gov (United States)

    Kunze, Florian; Raes, Anneloes M L; Bruch, Heike

    2015-09-01

    This article extends the conceptual knowledge of average relative subjective age in organizations by exploring organizational-level antecedents and consequences of employees, on average, feeling younger than their chronological age. We draw from the theories of selection-optimization-compensation and socioemotional selectivity to build a theoretical framework for relative subjective age in organizations. We hypothesize that companies in which employees, on average, perceive themselves to be younger than they actually are have a higher average individual goal accomplishment and, in turn, experience higher company performance. We further hypothesize that employees' average experience of high work-related meaning relates to a lower subjective age in organizations. In addition, we assess the role of environmental dynamism and age-inclusive human resource management as moderators in this theoretical model. Through empirically testing this model in a multisource dataset, including 107 companies with 15,164 participating employees, we received support for the hypothesized relationships. Our results contribute to current debates in the scientific literature on age and have important practical implications in light of the demographic changes faced by many companies. This research indicates to both researchers and practitioners that it is not employees' chronological age but their subjective age, a factor that can be influenced, which drives organizational performance outcomes. (c) 2015 APA, all rights reserved).

  13. Effects of Background Music on Objective and Subjective Performance Measures in an Auditory BCI

    OpenAIRE

    Zhou, Sijie; Allison, Brendan Z.; Kübler, Andrea; Cichocki, Andrzej; Wang, Xingyu; Jin, Jing

    2016-01-01

    Several studies have explored brain computer interface (BCI) systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory, and other BCIs are typically studied without background music. Some work has explored the possibility of using po...

  14. Comparison of design procedures and observed performance of bridges subjected to lateral spreading

    OpenAIRE

    Turner, Benjamin J; Brandenberg, Scott J.; Stewart, Jonathan P.

    2014-01-01

    Recently developed guidelines for analyzing deep foundations in liquefiable soils are compared with the performance of a highway bridge and adjacent railroad bridge that suffered damage during the 2010 Mw 7.2 El Mayor-Cucapah earthquake in Baja California, Mexico. A span of the pile-supported railroad bridge collapsed due to movement of a pier from lateral spreading. The highway bridge, supported on drilled shafts, suffered moderate structural damage but did not collapse. An overview of the s...

  15. Subjective cognitive complaints and neuropsychological performance in former smokers with and without chronic obstructive pulmonary disease.

    Science.gov (United States)

    Brunette, Amanda M; Holm, Kristen E; Wamboldt, Frederick S; Kozora, Elizabeth; Moser, David J; Make, Barry J; Crapo, James D; Meschede, Kimberly; Weinberger, Howard D; Moreau, Kerrie L; Bowler, Russell P; Hoth, Karin F

    2017-08-02

    This study examined the association of perceived cognitive difficulties with objective cognitive performance in former smokers. We hypothesized that greater perceived cognitive difficulties would be associated with poorer performance on objective executive and memory tasks. Participants were 95 former smokers recruited from the COPDGene study. They completed questionnaires (including the Cognitive Difficulties Scale [CDS] and the Hospital Anxiety and Depression Scale [HADS]), neuropsychological assessment, and pulmonary function testing. Pearson correlations and t-tests were conducted to examine the bivariate association of the CDS (total score and subscales for attention/concentration, praxis, delayed recall, orientation for persons, temporal orientation, and prospective memory) with each domain of objective cognitive functioning (memory recall, executive functioning/processing speed, visuospatial processing, and language). Simultaneous multiple linear regression was used to further examine all statistically significant bivariate associations. The following covariates were included in all regression models: age, sex, pack-years, premorbid functioning (WRAT-IV Reading), HADS total score, and chronic obstructive pulmonary disease (COPD) status (yes/no based on GOLD criteria). In regression models, greater perceived cognitive difficulties overall (using CDS total score) were associated with poorer performance on executive functioning/processing speed tasks (b = -0.07, SE = 0.03, p = .037). Greater perceived cognitive difficulties on the CDS praxis subscale were associated with poorer performance on executive functioning/processing speed tasks (b = -3.65, SE = 1.25, p = .005), memory recall tasks (b = -4.60, SE = 1.75, p = .010), and language tasks (b = -3.89, SE = 1.39, p = .006). Clinicians should be aware that cognitive complaints may be indicative of problems with the executive functioning/processing speed and memory of former smokers with

  16. Criterion and Construct Validity of an Isometric Mid-Thigh Pull Dynamometer for Assessing Whole Body Strength in Professional Rugby League Players.

    Science.gov (United States)

    Dobbin, Nick; Hunwicks, Richard; Jones, Ben; Till, Kevin; Highton, Jamie; Twist, Craig

    2017-06-12

    The purpose of this study was to examine the criterion and construct validity of an isometric mid-thigh pull dynamometer to assess whole body strength in professional rugby league players. Fifty-six male rugby league players, (33 senior and 23 youth professional players) performed four isometric mid-thigh pull efforts (i.e. two on the dynamometer and two on the force platform) in a randomised and counterbalanced order. Isometric peak force was underestimated (P0.05) between the predicted and peak force from the force platform, and an adjusted R2 (79.6%), that represented shrinkage of 0.4% relative to the cross-validation model (80%). Peak force was greater for the senior compared to youth professionals using the dynamometer (2261.2 ± 222 cf. 1725.1 ± 298.0 N, respectively; P<0.05). The isometric mid-thigh pull assessed using a dynamometer underestimates criterion peak force but is capable of distinguishing muscle function characteristics between professional rugby league players of different standards.

  17. Ultrasonographic analysis of dorsal neck muscles thickness changes induced by isometric contraction of shoulder muscles: A comparison between patients with chronic neck pain and healthy controls.

    Science.gov (United States)

    Karimi, Noureddin; Rezasoltani, Asghar; Rahnama, Leila; Noori-Kochi, Farhang; Jaberzadeh, Shapour

    2016-04-01

    Altered pattern of muscle activity is commonly seen with chronic neck pain (CNP). However, limited investigations have been done on dorsal neck muscles' activity pattern while performing upper limb tasks in patients with CNP. To investigate dorsal neck muscles' thickness changes during isometric contraction of shoulder muscles. Case-control study. This study investigated dorsal neck muscles' thickness changes during isometric contraction of shoulder muscles in 20 healthy participants (mean age 27 ± 4.37) and 17 patients with CNP (mean age 29 ± 5.50). Effects of isometric force of shoulder muscles on dorsal neck muscles' thickness changes were also evaluated. Significant muscle × group interaction was observed for the dorsal neck muscles thickness changes (p = 0.008) indicating different pattern of muscle activity in terms of changes in muscle thickness of two groups. Significant main effects of direction was observed (P = 0.003), with the abduction had the greatest impact on changing the dorsal neck muscles thickness. patients with CNP showed altered pattern of muscle thickness changes in comparison to healthy participants. Isometric abduction of shoulder muscles induced the greatest changes of dorsal neck muscles thickness among other force directions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Effects of the handle diameter and tip angle of chopsticks on the food-serving performance of male subjects.

    Science.gov (United States)

    Wu, S P

    1995-12-01

    The effects of chopsticks handle diameter and tip angle on the food-serving performance of pinching food, pulling food, shearing food and thrusting food, were investigated in this study. A total of 24 male subjects was tested using 12 pairs of experimental chopsticks, consisting of three types of different handle diameters and four types of different tip angles. These results indicated that chopstick handle diameter and tip angle have a significant influence on eating efficiency, and that these two variables have a significant interaction. In addition, chopstick tip diameter also had significant effects on performance at the four tasks and subjective ratings. Generally, according to the results, when the chopsticks design is presented in terms of handle diameter, tip angle and tip diameter, a pair of chopsticks with 6 mm handle diameter x 2 degrees tip angle x 4 mm tip diameter would be optimum.

  19. Blackcurrant Alters Physiological Responses and Femoral Artery Diameter during Sustained Isometric Contraction

    Directory of Open Access Journals (Sweden)

    Matthew David Cook

    2017-05-01

    Full Text Available Blackcurrant is rich in anthocyanins that may affect exercise-induced physiological responses. We examined tissue oxygen saturation, muscle activity, cardiovascular responses and femoral artery diameter during a submaximal sustained isometric contraction. In a randomised, double-blind, crossover design, healthy men (n = 13, age: 25 ± 4 years, BMI: 25 ± 3 kg·m−2, mean ± SD ingested New Zealand blackcurrant (NZBC extract (600 mg∙day−1 CurraNZ™ or placebo (PL for 7-days separated by 14-days washout. Participants produced isometric maximal voluntary contractions (iMVC and a 120-s 30%iMVC of the quadriceps with electromyography (EMG, near-infrared spectroscopy, hemodynamic and ultrasound recordings. There was no effect of NZBC extract on iMVC (NZBC: 654 ± 73, PL: 650 ± 78 N. During the 30%iMVC with NZBC extract, total peripheral resistance, systolic, diastolic, and mean arterial pressure were lower with increased cardiac output and stroke volume. With NZBC extract, EMG root mean square of the vastus medialis and muscle oxygen saturation were lower with higher total haemoglobin. During the 30%iMVC, femoral artery diameter was increased with NZBC extract at 30 (6.9%, 60 (8.2%, 90 (7.7% and 120 s (6.0%. Intake of NZBC extract for 7-days altered cardiovascular responses, muscle oxygen saturation, muscle activity and femoral artery diameter during a 120-s 30%iMVC of the quadriceps. The present study provides insight into the potential mechanisms for enhanced exercise performance with intake of blackcurrant.

  20. Medical Student Dissection of Cadavers Improves Performance on Practical Exams but not on the NBME Anatomy Subject Exam

    OpenAIRE

    Sargent Jones, Leslie; Paulman, Lance E.; Thadani, Raj; Terracio, Louis

    2009-01-01

    We have examined whether cadaver dissection by first year medical students (MIs) affected their performance in two test measures: the NBME Gross Anatomy and Embryology Subject Exam (dissection-relevant questions only), and practical exams given at the end of each major section within the course. The dissections for the entire course were divided into 18 regional dissection units and each student was assigned to dissect one third of the regional units; the other two-thirds of the material was ...

  1. Functional knee brace use by non-injured subjects while performing an anaerobic capacity task: preliminary study.

    Science.gov (United States)

    Rishiraj, N; Taunton, J E; Lloyd-Smith, R; Niven, B; Regan, W; Woollard, R

    2010-12-01

    The objective of this paper was to investigate if performance was hindered in non-injured braced athletes during an anaerobic task. If performance was affected, could accommodation to wearing a knee brace occur and thus decreasing performance hindrance concern while using a functional knee brace (FKB). A 2x3 non-braced (NBr) and braced repeated measure factorial design. Five healthy athletes completed all testing. Subjects performed the Repeated High Intensity Shuttle Test (RHIST) over six days (three days NBr and three days braced). Running times were recorded each testing day to determine performance measures and percent fatigue levels while using a FKB and if accommodation to FKB use was possible. Non significant (F1,4=1.42, P=0.299) faster group mean performance time, was recorded for braced subjects relative to the non-braced condition. Although relatively faster performance levels were noted during the braced testing conditions during days 1 and 3 compared to the non-braced condition, these results were also not significant (F2,8=2.82, P=0.118). Lower percent fatigue level was recorded during all three braced days compared to non-braced days. Further, a tendency for accommodation to knee brace trend use was noted as the percentage performance difference between the two conditions had decreased by the last day of testing. Use of a knee brace did not hinder performance once accommodation to using the knee brace occurred and fatigue was not a factor while using a knee brace. Additional research, using a larger sample size and longer testing duration, is required to confirm the potential accommodation trend.

  2. Cardiopulmonary performance testing using a robotics-assisted tilt table: feasibility assessment in able-bodied subjects.

    Science.gov (United States)

    Saengsuwan, J; Laubacher, M; Nef, T; Hunt, K J

    2014-01-01

    Robotics-assisted tilt table technology was introduced for early rehabilitation of neurological patients. It provides cyclical stepping movement and physiological loading of the legs. The aim of the present study was to assess the feasibility of this type of device for peak cardiopulmonary performance testing using able-bodied subjects. A robotics-assisted tilt table was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Feasibility assessment focused on: (i) implementation (technical feasibility), and (ii) responsiveness (was there a measurable, high-level cardiopulmonary reaction?). For responsiveness testing, each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/min in female subjects and 8 W/min in males. 11 able-bodied subjects were included (9 male, 2 female; age 29.6 ± 7.1 years: mean ± SD). Resting oxygen uptake (O_{2}) was 4.6 ± 0.7 mL/min/kg and O_{2}peak was 32.4 ± 5.1 mL/min/kg; this mean O_{2}peak was 81.1% of the predicted peak value for cycle ergometry. Peak heart rate (HRpeak) was 177.5 ± 9.7 beats/min; all subjects reached at least 85% of their predicted HRpeak value. Respiratory exchange ratio (RER) at O_{2}peak was 1.02 ± 0.07. Peak work rate) was 61.3 ± 15.1 W. All subjects reported a Borg CR10 value for exertion and leg fatigue of 7 or more. The robotics-assisted tilt table is deemed feasible for peak cardiopulmonary performance testing: the approach was found to be technically implementable and substantial cardiopulmonary responses were observed. Further testing in neurologically-impaired subjects is warranted.

  3. School Achievement and Performance in Chilean High Schools: The Mediating Role of Subjective Wellbeing in School-Related Evaluations

    Directory of Open Access Journals (Sweden)

    Verónica López

    2017-07-01

    Full Text Available School achievement gaps and school failure are problematic issues in Latin America, and are mainly explained by the socio-economic status (SES of the students. What schools can do to improve school achievement and reduce school failure is a critical issue, both for school management and teacher training. In this study, we present the association of individual and school-related socio-emotional variables with school achievement and performance, controlling for the effects of SES. A probabilistic sample of 4,964 students, drawn from 191 schools enrolled in year 10 in urban areas of Chile, answered questionnaires assessing subjective wellbeing, social wellbeing in school, school climate, school social wellbeing and students’ perceptions of teachers’ wellbeing. Using structural equation modeling, and controlling for SES, we modeled subjective wellbeing as a mediator of the relationship between school-related variables, such as school climate and perception of teacher’s wellbeing, and (a school achievement, and (b school performance. School achievement was computed as a product of (a the probability of passing the school year, and (b the percentage of yearly attendance at school. Data on school achievement was drawn from administrative registries from the Chilean Ministry of Education. School performance was computed as the estimated grade point average (GPA at the end of the school year, based on the students’ previous 5-year GPAs, and was also obtained through administrative data of the last 5 years. Findings reveal the mediating role of subjective wellbeing in the relationship between school-related evaluations (students’ social wellbeing at school, their perception of teachers’ wellbeing and school climate and school achievement. For school achievement, two variables were mediated (students’ social wellbeing at school and school climate. However, for school performance, no significant mediations were found. We conclude that, on the

  4. School Achievement and Performance in Chilean High Schools: The Mediating Role of Subjective Wellbeing in School-Related Evaluations

    Science.gov (United States)

    López, Verónica; Oyanedel, Juan C.; Bilbao, Marian; Torres, Javier; Oyarzún, Denise; Morales, Macarena; Ascorra, Paula; Carrasco, Claudia

    2017-01-01

    School achievement gaps and school failure are problematic issues in Latin America, and are mainly explained by the socio-economic status (SES) of the students. What schools can do to improve school achievement and reduce school failure is a critical issue, both for school management and teacher training. In this study, we present the association of individual and school-related socio-emotional variables with school achievement and performance, controlling for the effects of SES. A probabilistic sample of 4,964 students, drawn from 191 schools enrolled in year 10 in urban areas of Chile, answered questionnaires assessing subjective wellbeing, social wellbeing in school, school climate, school social wellbeing and students’ perceptions of teachers’ wellbeing. Using structural equation modeling, and controlling for SES, we modeled subjective wellbeing as a mediator of the relationship between school-related variables, such as school climate and perception of teacher’s wellbeing, and (a) school achievement, and (b) school performance. School achievement was computed as a product of (a) the probability of passing the school year, and (b) the percentage of yearly attendance at school. Data on school achievement was drawn from administrative registries from the Chilean Ministry of Education. School performance was computed as the estimated grade point average (GPA) at the end of the school year, based on the students’ previous 5-year GPAs, and was also obtained through administrative data of the last 5 years. Findings reveal the mediating role of subjective wellbeing in the relationship between school-related evaluations (students’ social wellbeing at school, their perception of teachers’ wellbeing and school climate) and school achievement. For school achievement, two variables were mediated (students’ social wellbeing at school and school climate). However, for school performance, no significant mediations were found. We conclude that, on the one hand

  5. School Achievement and Performance in Chilean High Schools: The Mediating Role of Subjective Wellbeing in School-Related Evaluations.

    Science.gov (United States)

    López, Verónica; Oyanedel, Juan C; Bilbao, Marian; Torres, Javier; Oyarzún, Denise; Morales, Macarena; Ascorra, Paula; Carrasco, Claudia

    2017-01-01

    School achievement gaps and school failure are problematic issues in Latin America, and are mainly explained by the socio-economic status (SES) of the students. What schools can do to improve school achievement and reduce school failure is a critical issue, both for school management and teacher training. In this study, we present the association of individual and school-related socio-emotional variables with school achievement and performance, controlling for the effects of SES. A probabilistic sample of 4,964 students, drawn from 191 schools enrolled in year 10 in urban areas of Chile, answered questionnaires assessing subjective wellbeing, social wellbeing in school, school climate, school social wellbeing and students' perceptions of teachers' wellbeing. Using structural equation modeling, and controlling for SES, we modeled subjective wellbeing as a mediator of the relationship between school-related variables, such as school climate and perception of teacher's wellbeing, and (a) school achievement, and (b) school performance. School achievement was computed as a product of (a) the probability of passing the school year, and (b) the percentage of yearly attendance at school. Data on school achievement was drawn from administrative registries from the Chilean Ministry of Education. School performance was computed as the estimated grade point average (GPA) at the end of the school year, based on the students' previous 5-year GPAs, and was also obtained through administrative data of the last 5 years. Findings reveal the mediating role of subjective wellbeing in the relationship between school-related evaluations (students' social wellbeing at school, their perception of teachers' wellbeing and school climate) and school achievement. For school achievement, two variables were mediated (students' social wellbeing at school and school climate). However, for school performance, no significant mediations were found. We conclude that, on the one hand, after

  6. Eccentric training for shoulder abductors improves pain, function and isokinetic performance in subjects with shoulder impingement syndrome: a case series.

    Science.gov (United States)

    Camargo, Paula R; Avila, Mariana A; Alburquerque-Sendín, Francisco; Asso, Naoe A; Hashimoto, Larissa H; Salvini, Tania F

    2012-01-01

    Conservative treatments have been proposed for people with shoulder impingement syndrome (SIS), such as strengthening of the rotator cuff and scapular muscles and stretching of the soft tissues of the shoulder. However, there is a lack of studies analyzing the effectiveness of eccentric training in the treatment of SIS. To evaluate the effects of eccentric training for shoulder abductors on pain, function, and isokinetic performance during concentric and eccentric abduction of the shoulder in subjects with SIS. Twenty subjects (7 females, 34.2 SD 10.2 years, 1.7 SD 0.1 m, 78.0 SD 16.3 kg) with unilateral SIS completed the study protocol. Bilateral isokinetic eccentric training at 60º/s for shoulder abductors was performed for six consecutive weeks, twice a week, on alternate days. For each training day, three sets of 10 repetitions were performed with a 3-minute rest period between the sets for each side. The range of motion trained was 60° (ranging from 80° to 20°). The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was used to evaluate functional status and symptoms of the upper limbs. Peak torque, total work and acceleration time were measured during concentric and eccentric abduction of the arm at 60º/s and 180º/s using an isokinetic dynamometer. DASH scores, peak torque, total work and acceleration time improved (pshoulder abductors improves physical function of the upper limbs in subjects with SIS.

  7. Trajectories in glycemic control over time are associated with cognitive performance in elderly subjects with type 2 diabetes.

    Science.gov (United States)

    Ravona-Springer, Ramit; Heymann, Anthony; Schmeidler, James; Moshier, Erin; Godbold, James; Sano, Mary; Leroith, Derek; Johnson, Sterling; Preiss, Rachel; Koifman, Keren; Hoffman, Hadas; Silverman, Jeremy M; Beeri, Michal Schnaider

    2014-01-01

    To study the relationships of long-term trajectories of glycemic control with cognitive performance in cognitively normal elderly with type 2 diabetes (T2D). Subjects (n = 835) pertain to a diabetes registry (DR) established in 1998 with an average of 18 HbA1c measurements per subject, permitting identification of distinctive trajectory groups of HbA1c and examining their association with cognitive function in five domains: episodic memory, semantic categorization, attention/working memory, executive function, and overall cognition. Analyses of covariance compared cognitive function among the trajectory groups adjusting for sociodemographic, cardiovascular, diabetes-related covariates and depression. Subjects averaged 72.8 years of age. Six trajectories of HbA1c were identified, characterized by HbA1c level at entry into the DR (Higher/Lower), and trend over time (Stable/Decreasing/Increasing). Both groups with a trajectory of decreasing HbA1c levels had high HbA1c levels at entry into the DR (9.2%, 10.7%), and high, though decreasing, HbA1c levels over time. They had the worst cognitive performance, particularly in overall cognition (pperformed best in cognitive tests. Glycemic control trajectories, which better reflect chronicity of T2D than a single HbA1c measurement, predict cognitive performance. A trajectory of stable HbA1c levels over time is associated with better cognitive function.

  8. Concept mapping improves academic performance in problem solving questions in biochemistry subject.

    Science.gov (United States)

    Baig, Mukhtiar; Tariq, Saba; Rehman, Rehana; Ali, Sobia; Gazzaz, Zohair J

    2016-01-01

    To assess the effectiveness of concept mapping (CM) on the academic performance of medical students' in problem-solving as well as in declarative knowledge questions and their perception regarding CM. The present analytical and questionnaire-based study was carried out at Bahria University Medical and Dental College (BUMDC), Karachi, Pakistan. In this analytical study, students were assessed with problem-solving questions (A-type MCQs), and declarative knowledge questions (short essay questions), and 50% of the questions were from the topics learned by CM. Students also filled a 10-item, 3-point Likert scale questionnaire about their perception regarding the effectiveness of the CM approach, and two open-ended questions were also asked. There was a significant difference in the marks obtained in those problem-solving questions, which were learned by CM as compared to those topics which were taught by the traditional lectures (pstudents' perception regarding CM showed that majority of the students perceive that CM is a helpful technique and it is enjoyed by the students. In open-ended questions, the majority of the students commented positively about the effectiveness of CM. Our results indicate that CM improves academic performance in problem solving but not in declarative knowledge questions. Students' perception about the effectiveness of CM was overwhelmingly positive.

  9. Concept mapping improves academic performance in problem solving questions in biochemistry subject

    Science.gov (United States)

    Baig, Mukhtiar; Tariq, Saba; Rehman, Rehana; Ali, Sobia; Gazzaz, Zohair J

    2016-01-01

    Objective: To assess the effectiveness of concept mapping (CM) on the academic performance of medical students’ in problem-solving as well as in declarative knowledge questions and their perception regarding CM. Methods: The present analytical and questionnaire-based study was carried out at Bahria University Medical and Dental College (BUMDC), Karachi, Pakistan. In this analytical study, students were assessed with problem-solving questions (A-type MCQs), and declarative knowledge questions (short essay questions), and 50% of the questions were from the topics learned by CM. Students also filled a 10-item, 3-point Likert scale questionnaire about their perception regarding the effectiveness of the CM approach, and two open-ended questions were also asked. Results: There was a significant difference in the marks obtained in those problem-solving questions, which were learned by CM as compared to those topics which were taught by the traditional lectures (p<0.001), while no significant difference was observed in marks in declarative knowledge questions (p=0.704). Analysis of students’ perception regarding CM showed that majority of the students perceive that CM is a helpful technique and it is enjoyed by the students. In open-ended questions, the majority of the students commented positively about the effectiveness of CM. Conclusion: Our results indicate that CM improves academic performance in problem solving but not in declarative knowledge questions. Students’ perception about the effectiveness of CM was overwhelmingly positive. PMID:27648017

  10. Performance of dairy cattle subjected to different food strategies during the growing and finishing phases

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    Marcondes Dias de Freitas Neto

    2014-09-01

    Full Text Available The objective of this study was to evaluate the performance of the crossbreed animals, in feedlot, previously fed with different supplemented energetic systems and Brachiaria brizantha pasture. The treatments were: TAA – high level intake of energy during the growing and finishing phases; TAM – high intake of energy during the growing phase and medium intake of energy during of the finishing phase; TMA – medium intake of energy during growing phase and high intake of energy during finishing phase; TMM – medium intake of energy during the growing and finishing phases. During the growth phase the animals received supplementation of 1.0% and 0.5% body weight of animals. In the finishing phase, the animals were fed diets containing 50% of concentrate (medium intake of energy, TDN = 71% or 80% of concentrate (high intake of energy, TDN = 80% in the dry matter of the total diet. The animals of the TAA and TAM treatments had higher average body weight at the beginning of feedlot due to that achieved average slaughter weights of 42 and 21 days less than the other treatments. The animals of the TAA and TAM treatments were more dry matter intake (P 0.05 between treatments for these measures at the end of the termination. The high level of energy supplementation during the growing phase allowed animals to a greater initial weight input in confinement, and consequently, the best performance.

  11. Artificial gait in complete spinal cord injured subjects: how to assess clinical performance

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    Karla Rocha Pithon

    2015-02-01

    Full Text Available Objective Adapt the 6 minutes walking test (6MWT to artificial gait in complete spinal cord injured (SCI patients aided by neuromuscular electrical stimulation. Method Nine male individuals with paraplegia (AIS A participated in this study. Lesion levels varied between T4 and T12 and time post injured from 4 to 13 years. Patients performed 6MWT 1 and 6MWT 2. They used neuromuscular electrical stimulation, and were aided by a walker. The differences between two 6MWT were assessed by using a paired t test. Multiple r-squared was also calculated. Results The 6MWT 1 and 6MWT 2 were not statistically different for heart rate, distance, mean speed and blood pressure. Multiple r-squared (r2 = 0.96 explained 96% of the variation in the distance walked. Conclusion The use of 6MWT in artificial gait towards assessing exercise walking capacity is reproducible and easy to apply. It can be used to assess SCI artificial gait clinical performance.

  12. Interaction between physiological and subjective states predicts the effect of a judging panel on the postures of cellists in performance

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    Satoshi eEndo

    2014-08-01

    Full Text Available This study investigated the effect of a panel of judges on the movements and postures of cellists in performance. 24 expert cellists played a short piece of music, to a metronome beat, in the presence and absence of the panel. Kinematic analyses showed that in the presence of the panel the temporal execution of left arm shifting movements became less variable and closer to the metronome beat. In contrast, the panel's presence had no reliable effect on their spatial accuracy. A detailed postural analysis indicated that left elbow angle during execution of a given high note was correlated with level of heart rate, though the nature of this correlation was systematically affected by the relevant participant's subjective state: if anxious, a higher heart rate correlated with a more flexed elbow, if not anxious then with a more extended elbow. Our results suggest a change in physiological state alone does not reliably predict a change in behaviour in performing cellists, which instead depends on the interaction between physiological state and subjective experience of anxiety. This highlights a need to distinguish performance anxiety from physiological arousal, to which end we advocate currency for the specific term performance arousal to describe heightened physiological activity in a performer.

  13. A COMPARATIVE STUDY ON THE EFFECT OF SELF SNAGs VERSUS DYNAMIC ISOMETRIC EXERCISES IN DESK JOB PEOPLE WITH CHRONIC NECK PAIN

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    Ningombam Geetanjali Devi

    2015-10-01

    Full Text Available Background: Neck pain is a common global problem, an important source of disability Bad posture of neck with respect to chest is one of the commonest causes of chronic neck pain. This is common to the job related (e.g. computer professionals, clerks, bank employees where the neck is kept in a flexed position for long periods of time. The objectives of the study is to compare the effectiveness of self SNAGs with dynamic isometric exercise in chronic neck pain. Methods: It is a comparative experimental study. This study includes (N=40 desk job people with chronic neck pain subjects with age group of 25-45 years. They were randomly assigned into 2 groups (Group A and B. Group A had 20 (N=20 subjects who are treated with self SNAGs, Group B had 20 (N=20 who are treated with dynamic isometric exercise using resistance band. The subjects were given intervention once a day for 6 weeks. Results: At the end of 6 weeks, both neck pain and disability decreased in both groups, range of motion had also improved statistically significantly in both groups, but the results showed that the pain scores are significantly improved in group A( t = -2.707 which is significant at 5% level of significance (p = 0.01. It has been inferred that VAS decreases more when self SNAGs was applied and the difference of means of NDI, t = -4.468 which is highly significant (p = 0.00 implying that NDI decrease more when self SNAGs was applied as compared to dynamic isometric exercise. Conclusion: From the above study it is concluded that, self SNAGs is an effective way of decreasing pain and increasing functional ability when compared to dynamic isometric exercise using resistance band.

  14. Effect of slow rhythmic voluntary breathing pattern on isometric handgrip among health care students

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    Rajajeyakumar M, Janitha A, Madanmohan, Balachander J

    2014-11-01

    Full Text Available Introduction: Hand grip strength is a widely used test in experimental and epidemiologicalstudies. The measure of hand grip strength is influenced by several factors, including age; gender; different angle of the shoulder, elbow, forearm, and wrist; and posture.So we planned to study theeffect of slow voluntary breathing exercise (Savitri Pranayam onthe various strengths of isometric hand grip (IHG amongyoung health care students.Methods: The present study was conducted on 60 volunteers 17-20 yrs.The subjects were randomly assigned to Pranayam and control groups. They were divided into two groups: control (n=30, Savitri (n=30 Savitri group were practiced slow yogic breathing for three months, Paired’ test was done to compare the values within group and unpaired’ test was done to compare the values between male and female subjects.Results: In Savitri Pranayam group, the blood pressure responses to IHG were higher in males, as compared to females.The rate pressure product (RPP also decreased during IHG 60%. A decrease in SBP and DBP was observed at the end of the study period. Briefly, a gender difference in various parameters such as MAP, QTc existed in the control group at the beginning of the study and the differences persisted at the end of three months.Conclusion: Our study reported that slow Pranayam are known to enhance parasympathetic tone, produce a highly significant decrease in oxygen consumption and psychosomatic relaxation.

  15. RADIATION PERFORMANCE OF GAN AND INAS/GAAS QUANTUM DOT BASED DEVICES SUBJECTED TO NEUTRON RADIATION

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    Dhiyauddin Ahmad Fauzi

    2017-05-01

    Full Text Available In addition to their useful optoelectronics functions, gallium nitride (GaN and quantum dots (QDs based structures are also known for their radiation hardness properties. With demands on such semiconductor material structures, it is important to investigate the differences in reliability and radiation hardness properties of these two devices. For this purpose, three sets of GaN light-emitting diode (LED and InAs/GaAs dot-in-a well (DWELL samples were irradiated with thermal neutron of fluence ranging from 3×1013 to 6×1014 neutron/cm2 in PUSPATI TRIGA research reactor. The radiation performances for each device were evaluated based on the current-voltage (I-V and capacitance-voltage (C-V electrical characterisation method. Results suggested that the GaN based sample is less susceptible to electrical changes due to the thermal neutron radiation effects compared to the QD based sample.

  16. Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

    Science.gov (United States)

    Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

    2017-12-01

    The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

  17. Attaining and maintaining isometric and isokinetic goals of the Shaker exercise.

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    Easterling, Caryn; Grande, Barbara; Kern, Mark; Sears, Karri; Shaker, Reza

    2005-01-01

    Previous studies have shown that the Shaker Exercise is effective in restoring oral intake in patients with deglutitive failure due to upper esophageal sphincter (UES) dysfunction. Our aim was to determine (1) exerciser compliance among healthy older adults, (2) number of days required to attain the isometric (IM) and isokinetic (IK) exercise goals, (3) rate and reason for dropout of exercisers, and (4) complaints associated with performance of the exercise. Twenty-six nondysphagic older adults were enrolled from an independent-living community (66-93 yr) to perform the Shaker Exercise. Each participant completed a questionnaire on exercise performance and its associated difficulties three times a day for six weeks. Four randomly chosen nondysphagic participants underwent pre- and postexercise videofluoroscopic swallow studies for biomechanical measurements. Maximum anterior hyoid and laryngeal excursions, as well as maximum anteroposterior UES opening increased (pShaker Exercise performance goals varied among participants. IK was more easily attained than IM. Only 50% and 70% of those enrolled initially were able to complete the exercise duration and attain its IK and IM goals, respectively. However, those who stayed in the program attained the IK and IM goals (100% and 74%, respectively). Most dropouts occurred in the first two weeks of exercise. Performance of the exercise was associated with mild muscle discomfort that resolved spontaneously after a couple of weeks. We concluded that although the Shaker Exercise can be performed independently, a structured and gradually progressive program is needed to attain the exercise goals completely.

  18. Effects of team-based learning on perceived teamwork and academic performance in a health assessment subject.

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    Park, Hyung-Ran; Kim, Chun-Ja; Park, Jee-Won; Park, Eunyoung

    2015-01-01

    The purpose of this study was to examine the effectiveness of team-based learning (a well-recognized learning and teaching strategy), applied in a health assessment subject, on nursing students' perceived teamwork (team-efficacy and team skills) and academic performance (individual and team readiness assurance tests, and examination scores). A prospective, one-group, pre- and post-test design enrolled a convenience sample of 74 second-year nursing students at a university in Suwon, Korea. Team-based learning was applied in a 2-credit health assessment subject over a 16-week semester. All students received written material one week before each class for readiness preparation. After administering individual- and team-readiness assurance tests consecutively, the subject instructor gave immediate feedback and delivered a mini-lecture to the students. Finally, students carried out skill based application exercises. The findings showed significant improvements in the mean scores of students' perceived teamwork after the introduction of team-based learning. In addition, team-efficacy was associated with team-adaptability skills and team-interpersonal skills. Regarding academic performance, team readiness assurance tests were significantly higher than individual readiness assurance tests over time. Individual readiness assurance tests were significantly related with examination scores, while team readiness assurance tests were correlated with team-efficacy and team-interpersonal skills. The application of team-based learning in a health assessment subject can enhance students' perceived teamwork and academic performance. This finding suggests that team-based learning may be an effective learning and teaching strategy for improving team-work of nursing students, who need to collaborate and effectively communicate with health care providers to improve patients' health.

  19. The effect of subjective awareness measures on performance in artificial grammar learning task.

    Science.gov (United States)

    Ivanchei, Ivan I; Moroshkina, Nadezhda V

    2018-01-01

    Systematic research into implicit learning requires well-developed awareness-measurement techniques. Recently, trial-by-trial measures have been widely used. However, they can increase complexity of a study because they are an additional experimental variable. We tested the effects of these measures on performance in artificial grammar learning study. Four groups of participants were assigned to different awareness measures conditions: confidence ratings, post-decision wagering, decision strategy attribution or none. Decision-strategy-attribution participants demonstrated better grammar learning and longer response times compared to controls. They also exhibited a conservative bias. Grammaticality by itself was a stronger predictor of strings endorsement in decision-strategy-attribution group compared to other groups. Confidence ratings and post-decision wagering only affected the response times. These results were supported by an additional experiment that used a balanced chunk strength design. We conclude that a decision-strategy-attribution procedure may force participants to adopt an analytical decision-making strategy and rely mostly on conscious knowledge of artificial grammar. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. PERFORMANCE-RELIABILITY – THE MAIN SUBJECT OF THE BANKING ANALYSIS OF THE CREDITED SOCIETIES

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    AVRAM (BOITOŞ CAMELIA

    2013-12-01

    Full Text Available Since the crediting activity occupies the primary role in any banking institution, the necessity of study and its analysis is required by following some steps both at a microeconomic level and at a macroeconomic one. Going over the theme, which aims at the importance of a thorough study of the clients' reliability for highlighting the existing risks in the banking activity in general, and particularly in the crediting activity, becomes as more interesting as their approach at the level of the member states of the European Union tends towards a common theme. Starting from these premises, we have considered as being extremely important the selection of a research theme which aims at the risks in the crediting activity, emphasizing the analysis of the clients' reliability both in the decision of crediting in order to assume the risk of credit and in determining the financial and banking performances. Being given the complexity of the existing risks in the banking activity in general and particularly of the credit risk, the clients' reliability represents an extremely important field, of research and application, bearing in mind both the actual stage of developing the Romanian banking system and the attempts of its alignment to the requirements imposed by the European Union.

  1. Performance Evaluation of Submerged Floating Tunnel Subjected to Hydrodynamic and Seismic Excitations

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    Naik Muhammad

    2017-10-01

    Full Text Available Submerged floating tunnels (SFTs are innovative structural solutions to waterway crossings, such as sea-straits, fjords and lakes. As the width and depth of straits increase, the conventional structures such as cable-supported bridges, underground tunnels or immersed tunnels become uneconomical alternatives. For the realization of SFT, the structural response under extreme environmental conditions needs to be evaluated properly. This study evaluates the displacements and internal forces of SFT under hydrodynamic and three-dimensional seismic excitations to check the global performance of an SFT in order to conclude on the optimum design. The formulations incorporate modeling of ocean waves, currents and mooring cables. The SFT responses were evaluated using three different mooring cable arrangements to determine the stability of the mooring configuration, and the most promising configuration was then used for further investigations. A comparison of static, hydrodynamic and seismic response envelope curves of the SFT is provided to determine the dominant structural response. The study produces useful conclusions regarding the structural behavior of the SFT using a three-dimensional numerical model.

  2. Electromechanical performance of induction motor/drive systems subjected to voltage sags

    Science.gov (United States)

    Tunaboylu, Serdar N.

    Induction Motors are workhorses for many industries. They are extensively utilized in industrial variable-frequency drive (VFD) or adjustable-speed drive (ASD) applications as well as constant speed applications. Recent advances in power electronics have made AC motor drives an economically viable solution for ASD applications traditionally dominated by dc motor drives. In this study, electromechanical performance variables of an Induction Motor (IM) have been studied during the balanced voltage sags. For this purpose a laboratory prototype of an industrial mixer has been designed. IM has been coupled to a speed reducer that is worm gear type with a ratio 10 to 1. Then the reducer is vertically coupled to a food process mixer within a metal canister. The mixer represents a high friction load with practically zero inertia. Voltage, current, speed, and power measurements have been collected and compared with the simulation results from Simnon. An open-loop control Volts per Hertz boost strategy has been used in order to compensate the speed loss during the three-phase balanced voltage sags. Both compensated and uncompensated cases have been run and compared with simulation results. Results are verified with a reasonably good agreement that the total system modeling is successful and boost compensation circuit is effective.

  3. Assessment of Mechanical Properties and Damage of High Performance Concrete Subjected to Magnesium Sulfate Environment

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    Sheng Cang

    2017-01-01

    Full Text Available Sulfate attack is one of the most important problems affecting concrete structures, especially magnesium sulfate attack. This paper presents an investigation on the mechanical properties and damage evolution of high performance concrete (HPC with different contents of fly ash exposure to magnesium sulfate environment. The microstructure, porosity, mass loss, dimensional variation, compressive strength, and splitting tensile strength of HPC were investigated at various erosion times up to 392 days. The ultrasonic pulse velocity (UPV propagation in HPC at different erosion time was determined by using ultrasonic testing technique. A relationship between damage and UPV of HPC was derived according to damage mechanics, and a correlation between the damage of HPC and erosion time was obtained eventually. The results indicated that (1 the average increasing amplitude of porosity for HPCs was 34.01% before and after exposure to magnesium sulfate solution; (2 the damage evolution of HPCs under sulfate attack could be described by an exponential fitting; (3 HPC containing 20% fly ash had the strongest resistance to magnesium sulfate attack.

  4. Differences in performance on the functional movement screen between chronic low back pain patients and healthy control subjects.

    Science.gov (United States)

    Ko, Min-Joo; Noh, Kyung-Hee; Kang, Min-Hyeok; Oh, Jae-Seop

    2016-07-01

    [Purpose] Differences in scores on the Functional Movement Screen between patients with chronic lower back pain and healthy control subjects were investigated. [Subjects and Methods] In all, 20 chronic lower back pain patients and 20 healthy control subjects were recruited. Chronic lower back pain patients and healthy controls performed the Functional Movement Screen (deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability pushup, and rotary stability). The Mann-Whitney test was used to analyze differences in Functional Movement Screen scores between the two groups. [Results] Chronic lower back pain patients scored lower on the Functional Movement Screen total composite compared with healthy control subjects. Chronic lower back pain patients scored lower on Functional Movement Screen subtests including the deep squat, hurdle step, active straight leg raise, and rotary stability tests. [Conclusion] The deep squat, hurdle step, active straight leg raise, and rotary stability tasks of the Functional Movement Screen can be recommended as a functional assessment tools to identify functional deficits in chronic lower back pain patients.

  5. Quantification of intestinal bacteria, operating cost and performance of fingerlings Nile tilapia subjected to probiotics

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    Nilton Garcia-Marengoni

    2015-05-01

    Full Text Available The use of microorganisms of the genus Bacillus in aquaculture is a nutritional management practice that is rapidly expanding in regions with intensive fish farming. This study aimed to quantify the total bacteria and total coliforms from the intestinal microbiota and estimate the partial operating costs and growth performance of Nile tilapia (Oreochromis niloticus of the GIFT strain. A total of 1,200 post-larvae (24.7 ± 0.50 mg were distributed into 24 aquaria (0.03-m³ capacity within a completely randomized design in 2 x 3 factorial (phase x bacteria, with four replications. Each aquarium, containing 50 post-larvae (sex reversal phase or 30 fish (fingerlings phase, it was considered to be an experimental unit, consisting of three treatments (diet+Bacillus subtilis C-3102, diet+Bacillus cereus var. toyoi and diet without probiotic addition. The quantification of the total bacteria and total coliforms of the intestinal microbiota of tilapia were influenced (P 0.05 by adding probiotics in the diets and no effect of the interaction between phase and bacteria was observed. The weight gain, average daily weight gain, specific growth rate and apparent feed conversion were not affected (P > 0.05 by inclusion of probiotics as part of the diets. The inclusion of B. subtilis and B. cereus as part of diets for Nile tilapia promotes intestinal colonization and improves the survival rate without negatively influencing the feed intake, total biomass, gross revenue and partial operating costs and net revenue. Therefore it recommends the use of these probiotics to growth of tilapia fingerlings Nile, GIFT strain.

  6. Cognitive performance and the thymus among HIV-infected subjects receiving HAART

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    Maria J Miguez-Burbano

    2008-06-01

    Full Text Available Maria J Miguez-Burbano1, John E Lewis2, Jose Moreno3, Joel Fishman41Robert Stempel School of Public Health & School of Medicine, Florida International University, Miami, FL, USA; 2Department of Psychiatry and Behavioral Sciences, 3Department of Medicine, 4Department of Radiology, University of Miami Miller School of Medicine, Miami, FL, USAObjective: To evaluate the impact of alcohol use, which is widespread in human immunodeficiency virus (HIV+ individuals, on highly active antiretroviral therapy (HAART-associated immune and cognitive improvements and the relationship between those two responses.Methods: In a case-control longitudinal study, thymic volume, cognition, and immune responses were evaluated at baseline and after 6 months therapy in HIV+ and HIV- controls. Cognitive performance was evaluated using the HIV Dementia Score (HDS and the California Verbal Learning Test (CVLT.Results: Prior to HAART, thymic volume varied considerably from 2.7 to 29.3 cm3 (11 ± 7.2 cm3. Thymic volume at baseline showed a significantly inverse correlation with the patient’s number of years of drinking (r2 = 0.207; p < 0.01, as well as HDS and the CVLT scores in both HIV-infected (r2 = 0.37, p = 0.03 and noninfected (r2 = 0.8, p = 0.01. HIV-infected individuals with a small thymic volume scored in the demented range, as compared with those with a larger thymus (7 ± 2.7 vs. 12 ± 2.3, p = 0.005. After HAART, light/moderate drinkers exhibited thymus size twice that of heavy drinkers (14.8 ± 10.4 vs. 6.9 ± 3.3 cm3.Conclusions: HAART-associated increases of thymus volume appear to be negatively affected by alcohol consumption and significantly related to their cognitive status. This result could have important clinical implications.Keywords: thymus, CNS, immune, alcohol

  7. Acute Response to a 2-Minute Isometric Exercise Test Predicts the Blood Pressure-Lowering Efficacy of Isometric Resistance Training in Young Adults.

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    Somani, Yasina B; Baross, Anthony W; Brook, Robert D; Milne, Kevin J; McGowan, Cheri L; Swaine, Ian L

    2018-02-09

    This work aimed to explore whether different forms of a simple isometric exercise test could be used to predict the blood pressure (BP)-lowering efficacy of different types of isometric resistance training (IRT) in healthy young adults. In light of the emphasis on primary prevention of hypertension, identifying those with normal BP who will respond to IRT is important. Also, heightened BP reactivity increases hypertension risk, and as IRT reduces BP reactivity in patients with hypertension, it warrants further investigation in a healthy population. Forty-six young men and women (24 ± 5 years; 116 ± 10/ 68 ± 8 mm Hg) were recruited from 2 study sites: Windsor, Canada (n = 26; 13 women), and Northampton, United Kingdom (n = 20; 10 women). Resting BP and BP reactivity to an isometric exercise test were assessed prior to and following 10 weeks of thrice weekly IRT. Canadian participants trained on a handgrip dynamometer (isometric handgrip, IHG), while participants in the UK trained on an isometric leg extension dynamometer (ILE). Men and women enrolled in both interventions demonstrated significant reductions in systolic BP (P exercise test appears to be a viable tool to identify individuals who may respond to traditional IRT prescription.

  8. Quantitative performance of E-Scribe warehouse in detecting quality issues with digital annotated ECG data from healthy subjects.

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    Sarapa, Nenad; Mortara, Justin L; Brown, Barry D; Isola, Lamberto; Badilini, Fabio

    2008-05-01

    The US Food and Drug Administration recommends submission of digital electrocardiograms in the standard HL7 XML format into the electrocardiogram warehouse to support preapproval review of new drug applications. The Food and Drug Administration scrutinizes electrocardiogram quality by viewing the annotated waveforms and scoring electrocardiogram quality by the warehouse algorithms. Part of the Food and Drug Administration warehouse is commercially available to sponsors as the E-Scribe Warehouse. The authors tested the performance of E-Scribe Warehouse algorithms by quantifying electrocardiogram acquisition quality, adherence to QT annotation protocol, and T-wave signal strength in 2 data sets: "reference" (104 digital electrocardiograms from a phase I study with sotalol in 26 healthy subjects with QT annotations by computer-assisted manual adjustment) and "test" (the same electrocardiograms with an intentionally introduced predefined number of quality issues). The E-Scribe Warehouse correctly detected differences between the 2 sets expected from the number and pattern of errors in the "test" set (except for 1 subject with QT misannotated in different leads of serial electrocardiograms) and confirmed the absence of differences where none was expected. E-Scribe Warehouse scores below the threshold value identified individual electrocardiograms with questionable T-wave signal strength. The E-Scribe Warehouse showed satisfactory performance in detecting electrocardiogram quality issues that may impair reliability of QTc assessment in clinical trials in healthy subjects.

  9. Cognitive Performance in Subjects With Multiple Sclerosis Is Robustly Influenced by Gender in Canonical-Correlation Analysis.

    Science.gov (United States)

    Lin, Sue-Jin; Lam, Janet; Beveridge, Samantha; Vavasour, Irene; Traboulsee, Anthony; Li, David K B; MacKay, Alex; McKeown, Martin; Kosaka, Brenda

    2017-01-01

    The authors explored the relations between clinical/demographic characteristics and performance on a neuropsychological battery (eight tests) in a cohort (N=46) of multiple sclerosis (MS) subjects. Findings resulted from a secondary analysis of a study examining the relationships between imaging biomarkers in MS and cognitive tasks of executive functioning. The objective was to determine whether the overlapping test results could be judiciously combined and associated with clinical/demographic variables. Canonical-correlation analysis (CCA) was utilized, and it was found that differences between performance on untimed tests, and the sum of performance on timed Trail-Making Tests, Parts A and B, best matched clinical/demographic variables, and gender was the most important feature.

  10. Coronary vasomotor responses to isometric handgrip exercise are primarily mediated by nitric oxide: a noninvasive MRI test of coronary endothelial function.

    Science.gov (United States)

    Hays, Allison G; Iantorno, Micaela; Soleimanifard, Sahar; Steinberg, Angela; Schär, Michael; Gerstenblith, Gary; Stuber, Matthias; Weiss, Robert G

    2015-06-01

    Endothelial cell release of nitric oxide (NO) is a defining characteristic of nondiseased arteries, and abnormal endothelial NO release is both a marker of early atherosclerosis and a predictor of its progression and future events. Healthy coronaries respond to endothelial-dependent stressors with vasodilatation and increased coronary blood flow (CBF), but those with endothelial dysfunction respond with paradoxical vasoconstriction and reduced CBF. Recently, coronary MRI and isometric handgrip exercise (IHE) were reported to noninvasively quantify coronary endothelial function (CEF). However, it is not known whether the coronary response to IHE is actually mediated by NO and/or whether it is reproducible over weeks. To determine the contribution of NO, we studied the coronary response to IHE before and during infusion of N(G)-monomethyl-l-arginine (l-NMMA, 0.3 mg·kg(-1)·min(-1)), a NO-synthase inhibitor, in healthy volunteers. For reproducibility, we performed two MRI-IHE studies ~8 wk apart in healthy subjects and patients with coronary artery disease (CAD). Changes from rest to IHE in coronary cross-sectional area (%CSA) and diastolic CBF (%CBF) were quantified. l-NMMA completely blocked normal coronary vasodilation during IHE [%CSA, 12.9 ± 2.5 (mean ± SE, placebo) vs. -0.3 ± 1.6% (l-NMMA); P exam of NO-mediated CEF promises to be useful for studying CAD pathogenesis in low-risk populations and for evaluating translational strategies designed to alter CAD in patients.

  11. Acute effects of maximal isometric muscle action of the elbow extensors on contralateral dynamic task of the elbow flexors: a pilot study

    Directory of Open Access Journals (Sweden)

    Cauê V La Scala Teixeira

    2017-12-01

    Full Text Available ABSTRACT Aim the aim was to investigate the influence of a maximal isometric muscle action of the elbow extensors on the contralateral dynamic task of the elbow flexors. Methods Seventeen recreationally trained men (23.3 ± 4.9 yrs, BMI: 24.8 ± 2.2 Kg/m² underwent two randomized different testing sessions separated by one week. In the control session (CON all subjects performed a maximum number of repetitions test (RMs at 75%1RM using the right elbow flexors. The experimental session (EXP was similar to the CON; however, all subjects were instructed to perform RMs at 75%1RM by using the right elbow flexors and maintaining the maximal voluntary contraction of the left elbow extensors during the test. RMs, rating of perceived exertion (RPE, and training volume (TV were measured and compared between sessions. Results The EXP showed a significant 10.4% increase on the RMs (13.8 vs. 12.5, p < 0.001, d = 0.44 and 12.1% increase in TV (238.0 vs. 212.4 kg, p < 0.001, d = 0.43 than CON. No differences were observed for RPE between sessions. Conclusion The maximum voluntary contraction of the left elbow extensors increased the RMs of the contralateral elbow flexors, reflecting a higher TV, and no differences in the RPE. Our results suggest that the investigated method may be a viable and practical alternative to increase the acute strength performance of elbow flexors when using submaximal loads.

  12. The effects of receiver placement on probe microphone, performance, and subjective measures with open canal hearing instruments.

    Science.gov (United States)

    Alworth, Lynzee N; Plyler, Patrick N; Reber, Monika Bertges; Johnstone, Patti M

    2010-04-01

    Open canal hearing instruments differ in method of sound delivery to the ear canal, distance between the microphone and the receiver, and physical size of the devices. Moreover, RITA (receiver in the aid) and RITE (receiver in the ear) hearing instruments may also differ in terms of retention and comfort as well as ease of use and care for certain individuals. What remains unclear, however, is if any or all of the abovementioned factors contribute to hearing aid outcome. To determine the effect of receiver location on performance and/or preference of listeners using open canal hearing instruments. An experimental study in which subjects were exposed to a repeated measures design. Twenty-five adult listeners with mild sloping to moderately severe sensorineural hearing loss (mean age 67 yr). Participants completed two six-week trial periods for each device type. Probe microphone, objective, and subjective measures (quiet, noise) were conducted unaided and aided at the end of each trial period. Occlusion effect results were not significantly different between the RITA and RITE instruments; however, frequency range was extended in the RITE instruments, resulting in significantly greater maximum gain for the RITE instruments than the RITA instruments at 4000 and 6000 Hz. Objective performance in quiet or in noise was unaffected by receiver location. Subjective measures revealed significantly greater satisfaction ratings for the RITE than for the RITA instruments. Similarly, preference in quiet and overall preference were significantly greater for the RITE than for the RITA instruments. Although no occlusion differences were noted between instruments, the RITE did demonstrate a significant difference in reserve gain before feedback at 4000 and 6000 Hz. Objectively; no positive benefit was noted between unaided and aided conditions on speech recognition tests. These results suggest that such testing may not be sensitive enough to determine aided benefit with open canal

  13. Finger Flexor Force Influences Performance in Senior Male Air Pistol Olympic Shooting.

    Science.gov (United States)

    Mon, Daniel; Zakynthinaki, María S; Cordente, Carlos A; Antón, Antonio J Monroy; Rodríguez, Bárbara Rodríguez; Jiménez, David López

    2015-01-01

    The ability to stabilize the gun is crucial for performance in Olympic pistol shooting and is thought to be related to the shooters muscular strength. The present study examines the relation between performance and finger flexor force as well as shoulder abduction isometric force in senior male air pistol shooting. 46 Spanish national level shooters served as test subjects of the study. Two maximal force tests were carried out recording handgrip and deltoid force data under competition conditions, during the official training time at national Spanish championships. Performance was measured as the total score of 60 shots at competition. Linear regressions were calculated to examine the relations between performance and peak and average finger flexor forces, peak and average finger flexor forces relative to the BMI, peak and average shoulder abduction isometric forces, peak shoulder abduction isometric force relative to the BMI. The connection between performance and other variables such as age, weight, height, BMI, experience in years and training hours per week was also analyzed. Significant correlations were found between performance at competition and average and peak finger flexor forces. For the rest of the force variables no significant correlations were found. Significant correlations were also found between performance at competition and experience as well as training hours. No significant correlations were found between performance and age, weight, height or BMI. The study concludes that hand grip strength training programs are necessary for performance in air pistol shooting.

  14. Finger Flexor Force Influences Performance in Senior Male Air Pistol Olympic Shooting.

    Directory of Open Access Journals (Sweden)

    Daniel Mon

    Full Text Available The ability to stabilize the gun is crucial for performance in Olympic pistol shooting and is thought to be related to the shooters muscular strength. The present study examines the relation between performance and finger flexor force as well as shoulder abduction isometric force in senior male air pistol shooting. 46 Spanish national level shooters served as test subjects of the study. Two maximal force tests were carried out recording handgrip and deltoid force data under competition conditions, during the official training time at national Spanish championships. Performance was measured as the total score of 60 shots at competition. Linear regressions were calculated to examine the relations between performance and peak and average finger flexor forces, peak and average finger flexor forces relative to the BMI, peak and average shoulder abduction isometric forces, peak shoulder abduction isometric force relative to the BMI. The connection between performance and other variables such as age, weight, height, BMI, experience in years and training hours per week was also analyzed. Significant correlations were found between performance at competition and average and peak finger flexor forces. For the rest of the force variables no significant correlations were found. Significant correlations were also found between performance at competition and experience as well as training hours. No significant correlations were found between performance and age, weight, height or BMI. The study concludes that hand grip strength training programs are necessary for performance in air pistol shooting.

  15. A comparison of models of the isometric force of locust skeletal muscle in response to pulse train inputs.

    Science.gov (United States)

    Wilson, Emma; Rustighi, Emiliano; Newland, Philip L; Mace, Brian R

    2012-03-01

    Muscle models are an important tool in the development of new rehabilitation and diagnostic techniques. Many models have been proposed in the past, but little work has been done on comparing the performance of models. In this paper, seven models that describe the isometric force response to pulse train inputs are investigated. Five of the models are from the literature while two new models are also presented. Models are compared in terms of their ability to fit to isometric force data, using Akaike's and Bayesian information criteria and by examining the ability of each model to describe the underlying behaviour in response to individual pulses. Experimental data were collected by stimulating the locust extensor tibia muscle and measuring the force generated at the tibia. Parameters in each model were estimated by minimising the error between the modelled and actual force response for a set of training data. A separate set of test data, which included physiological kick-type data, was used to assess the models. It was found that a linear model performed the worst whereas a new model was found to perform the best. The parameter sensitivity of this new model was investigated using a one-at-a-time approach, and it found that the force response is not particularly sensitive to changes in any parameter.

  16. Effects of three therapeutic doses of codeine/paracetamol on driving performance, a psychomotor vigilance test, and subjective feelings.

    Science.gov (United States)

    Amato, Jean-Noël; Marie, Sullivan; Lelong-Boulouard, Véronique; Paillet-Loilier, Magalie; Berthelon, Catherine; Coquerel, Antoine; Denise, Pierre; Bocca, Marie-Laure

    2013-07-01

    Some recent pharmacoepidemiological studies revealed an elevated risk of driving accidents after opioid analgesics uses. Among analgesics, codeine is often associated with paracetamol in numerous pharmaceutical specialties. The objective of this study was to evaluate the dose-effect relationship of three usual therapeutic doses of codeine/paracetamol on driving ability, psychomotor performance, subjective alertness, in link with blood concentrations in healthy young volunteers. Driving performance, responses to psychomotor vigilance tests, and scales reflecting alertness were evaluated during the morning after drug intake in a double-blind, randomized, placebo-controlled study. Sixteen healthy volunteers (23.4 ± 2.7 years old, 8 men and 8 women) participated in this balanced, cross-over study. Three doses of codeine/paracetamol (20/400, 40/800, 60/1200 mg) were evaluated against placebo. Two blood samples were collected, 1 and 4 h after drug intake. In serum, codeine and morphine concentrations were determined in serum using high-performance liquid chromatography electrospray ionization-tandem mass spectrometry, and paracetamol concentrations using fluorescence polarization immunoassay. Driving and psychomotor performance were not affected by any of the three codeine/paracetamol doses. However, significant, though modest, correlations were observed between the driving parameters and both morphine and codeine blood concentrations. This study did not reveal any significant impairment in performance due to the three therapeutic doses used in healthy young volunteers. However, the relationships between drug blood concentration and behavioral measures suggest that an inter-subject variability in blood concentration may influence the power of the observed drug effect.

  17. A Comparison of Robotic Simulation Performance on Basic Virtual Reality Skills: Simulator Subjective Versus Objective Assessment Tools.

    Science.gov (United States)

    Dubin, Ariel K; Smith, Roger; Julian, Danielle; Tanaka, Alyssa; Mattingly, Patricia

    2017-07-27

    To answer the question of whether there is a difference between robotic virtual reality simulator performance assessment and validated human reviewers. Current surgical education relies heavily on simulation. Several assessment tools are available to the trainee, including the actual robotic simulator assessment metrics and the Global Evaluative Assessment of Robotic Skills (GEARS) metrics, both of which have been independently validated. GEARS is a rating scale through which human evaluators can score trainees' performances on 6 domains: depth perception, bimanual dexterity, efficiency, force sensitivity, autonomy, and robotic control. Each domain is scored on a 5-point Likert scale with anchors. We used 2 common robotic simulators, the dV-Trainer (dVT; Mimic Technologies Inc., Seattle, WA) and the da Vinci Skills Simulator (dVSS; Intuitive Surgical, Sunnyvale, CA), to compare the performance metrics of robotic surgical simulators with the GEARS for a basic robotic task on each simulator. A prospective single-blinded randomized study. A surgical education and training center. Surgeons and surgeons in training. Demographic information was collected including sex, age, level of training, specialty, and previous surgical and simulator experience. Subjects performed 2 trials of ring and rail 1 (RR1) on each of the 2 simulators (dVSS and dVT) after undergoing randomization and warm-up exercises. The second RR1 trial simulator performance was recorded, and the deidentified videos were sent to human reviewers using GEARS. Eight different simulator assessment metrics were identified and paired with a similar performance metric in the GEARS tool. The GEARS evaluation scores and simulator assessment scores were paired and a Spearman rho calculated for their level of correlation. Seventy-four subjects were enrolled in this randomized study with 9 subjects excluded for missing or incomplete data. There was a strong correlation between the GEARS score and the simulator metric

  18. Prediction of isometric motor tasks and effort levels based on high-density EMG in patients with incomplete spinal cord injury

    Science.gov (United States)

    Jordanić, Mislav; Rojas-Martínez, Mónica; Mañanas, Miguel Angel; Francesc Alonso, Joan

    2016-08-01

    Objective. The development of modern assistive and rehabilitation devices requires reliable and easy-to-use methods to extract neural information for control of devices. Group-specific pattern recognition identifiers are influenced by inter-subject variability. Based on high-density EMG (HD-EMG) maps, our research group has already shown that inter-subject muscle activation patterns exist in a population of healthy subjects. The aim of this paper is to analyze muscle activation patterns associated with four tasks (flexion/extension of the elbow, and supination/pronation of the forearm) at three different effort levels in a group of patients with incomplete Spinal Cord Injury (iSCI). Approach. Muscle activation patterns were evaluated by the automatic identification of these four isometric tasks along with the identification of levels of voluntary contractions. Two types of classifiers were considered in the identification: linear discriminant analysis and support vector machine. Main results. Results show that performance of classification increases when combining features extracted from intensity and spatial information of HD-EMG maps (accuracy = 97.5%). Moreover, when compared to a population with injuries at different levels, a lower variability between activation maps was obtained within a group of patients with similar injury suggesting stronger task-specific and effort-level-specific co-activation patterns, which enable better prediction results. Significance. Despite the challenge of identifying both the four tasks and the three effort levels in patients with iSCI, promising results were obtained which support the use of HD-EMG features for providing useful information regarding motion and force intention.

  19. The effects of imagery on fast isometric knee extensor torque development

    NARCIS (Netherlands)

    de Ruiter, C.J.; Hutter, R.I.; Icke, C; Groen, B; Gemmink, A; Smilde, H; de Haan, A.

    2012-01-01

    We hypothesized that imagery training would improve fast onset of neuromuscular activation and thereby fast knee extensor isometric torque development. Forty young healthy participants not involved in strength training, were assigned to one of four groups: physical training, imagery training,

  20. When does stress help or harm? The effects of stress controllability and subjective stress response on stroop performance.

    Science.gov (United States)

    Henderson, Roselinde K; Snyder, Hannah R; Gupta, Tina; Banich, Marie T

    2012-01-01

    The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, research suggests that the impact of stress on cognitive functioning depends on an individual's response to stressors: moderate responses to stress can lead to improved performance while extreme (high or low) responses can lead to impaired performance. The present studies tested the hypothesis that (1) learning to behaviorally control stressors leads to improved performance on a test of general executive functioning, the color-word Stroop, and that (2) this improvement emerges specifically for people who report moderate (subjective) responses to stress. Experiment 1: Stroop performance, measured before and after a stress manipulation, was compared across groups of undergraduate participants (n = 109). People who learned to control a noise stressor and received accurate performance feedback demonstrated reduced Stroop interference compared with people exposed to uncontrollable noise stress and feedback indicating an exaggerated rate of failure. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest reduction in Stroop interference. In contrast, in the group exposed to uncontrollable events, self-reported stress failed to predict performance. Experiment 2: In a second sample (n = 90), we specifically investigated the role of controllability by keeping the rate of failure feedback constant across groups. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest Stroop

  1. Performance evaluation method of electric energy data acquire system based on combination of subjective and objective weights

    Science.gov (United States)

    Gao, Chen; Ding, Zhongan; Deng, Bofa; Yan, Shengteng

    2017-10-01

    According to the characteristics of electric energy data acquire system (EEDAS), considering the availability of each index data and the connection between the index integrity, establishing the performance evaluation index system of electric energy data acquire system from three aspects as master station system, communication channel, terminal equipment. To determine the comprehensive weight of each index based on triangular fuzzy number analytic hierarchy process with entropy weight method, and both subjective preference and objective attribute are taken into consideration, thus realize the performance comprehensive evaluation more reasonable and reliable. Example analysis shows that, by combination with analytic hierarchy process (AHP) and triangle fuzzy numbers (TFN) to establish comprehensive index evaluation system based on entropy method, the evaluation results not only convenient and practical, but also more objective and accurate.

  2. Validation and Reliability of a Novel Test of Upper Body Isometric Strength

    Directory of Open Access Journals (Sweden)

    Bellar David

    2015-09-01

    Full Text Available The purpose of the present investigation was to examine the association of a novel test of upper body isometric strength against a 1RM bench press measurement. Forty college age adults (n = 20 female, n = 20 male; age 22.8 ± 2.8 years; body height 171.6 ± 10.8 cm; body mass 73.5 ± 16.3 kg; body fat 23.1 ± 5.4% volunteered for the present investigation. The participants reported to the lab on three occasions. The first visit included anthropometric measurements and familiarization with both the upper body isometric test and bench press exercise. The final visits were conducted in a randomized order, with one being a 1RM assessment on the bench press and the other consisting of three trials of the upper body isometric assessment. For the isometric test, participants were positioned in a “push-up” style position while tethered (stainless steel chain to a load cell (high frequency anchored to the ground. The peak isometric force was consistent across all three trials (ICC = 0.98 suggesting good reliability. Multiple regression analysis was completed with the predictors: peak isometric force, gender, against the outcome variable 1RM bench press. The analysis resulted in a significant model (r2 = 0.861, p≤0.001 with all predictor variables attaining significance in the model (p<0.05. Isometric peak strength had the greatest effect on the model (Beta = 5.19, p≤0.001. Results from this study suggest that the described isometric upper body strength assessment is likely a valid and reliable tool to determine strength. Further research is warranted to gather a larger pool of data in regard to this assessment.

  3. Isometric multipliers of Lp (G, X) Lp (G, X) Lp (G, X)

    Indian Academy of Sciences (India)

    We use the characterization of isometries of L p ( G , X ) onto itself to characterize the isometric, invertible, left multipliers of L p ( G , X ) for 1 ≤ < ∞, ≠ 2, under the assumption that is not the l p -direct sum of two non-zero subspaces. In fact we prove that if is an isometric left multiplier of L p ( G , X ) onto itself then ...

  4. A comparison of two gluteus maximus EMG maximum voluntary isometric contraction positions.

    Science.gov (United States)

    Contreras, Bret; Vigotsky, Andrew D; Schoenfeld, Brad J; Beardsley, Chris; Cronin, John

    2015-01-01

    Background. The purpose of this study was to compare the peak electromyography (EMG) of the most commonly-used position in the literature, the prone bent-leg (90°) hip extension against manual resistance applied to the distal thigh (PRONE), to a novel position, the standing glute squeeze (SQUEEZE). Methods. Surface EMG electrodes were placed on the upper and lower gluteus maximus of thirteen recreationally active females (age = 28.9 years; height = 164 cm; body mass = 58.2 kg), before three maximum voluntary isometric contraction (MVIC) trials for each position were obtained in a randomized, counterbalanced fashion. Results. No statistically significant (p < 0.05) differences were observed between PRONE (upper: 91.94%; lower: 94.52%) and SQUEEZE (upper: 92.04%; lower: 85.12%) for both the upper and lower gluteus maximus. Neither the PRONE nor SQUEEZE was more effective between all subjects. Conclusions. In agreement with other studies, no single testing position is ideal for every participant. Therefore, it is recommended that investigators employ multiple MVIC positions, when possible, to ensure accuracy. Future research should investigate a variety of gluteus maximus MVIC positions in heterogeneous samples.

  5. A comparison of two gluteus maximus EMG maximum voluntary isometric contraction positions

    Science.gov (United States)

    Contreras, Bret; Schoenfeld, Brad J.; Beardsley, Chris; Cronin, John

    2015-01-01

    Background. The purpose of this study was to compare the peak electromyography (EMG) of the most commonly-used position in the literature, the prone bent-leg (90°) hip extension against manual resistance applied to the distal thigh (PRONE), to a novel position, the standing glute squeeze (SQUEEZE). Methods. Surface EMG electrodes were placed on the upper and lower gluteus maximus of thirteen recreationally active females (age = 28.9 years; height = 164 cm; body mass = 58.2 kg), before three maximum voluntary isometric contraction (MVIC) trials for each position were obtained in a randomized, counterbalanced fashion. Results. No statistically significant (p < 0.05) differences were observed between PRONE (upper: 91.94%; lower: 94.52%) and SQUEEZE (upper: 92.04%; lower: 85.12%) for both the upper and lower gluteus maximus. Neither the PRONE nor SQUEEZE was more effective between all subjects. Conclusions. In agreement with other studies, no single testing position is ideal for every participant. Therefore, it is recommended that investigators employ multiple MVIC positions, when possible, to ensure accuracy. Future research should investigate a variety of gluteus maximus MVIC positions in heterogeneous samples. PMID:26417543

  6. A comparison of two gluteus maximus EMG maximum voluntary isometric contraction positions

    Directory of Open Access Journals (Sweden)

    Bret Contreras

    2015-09-01

    Full Text Available Background. The purpose of this study was to compare the peak electromyography (EMG of the most commonly-used position in the literature, the prone bent-leg (90° hip extension against manual resistance applied to the distal thigh (PRONE, to a novel position, the standing glute squeeze (SQUEEZE.Methods. Surface EMG electrodes were placed on the upper and lower gluteus maximus of thirteen recreationally active females (age = 28.9 years; height = 164 cm; body mass = 58.2 kg, before three maximum voluntary isometric contraction (MVIC trials for each position were obtained in a randomized, counterbalanced fashion.Results. No statistically significant (p < 0.05 differences were observed between PRONE (upper: 91.94%; lower: 94.52% and SQUEEZE (upper: 92.04%; lower: 85.12% for both the upper and lower gluteus maximus. Neither the PRONE nor SQUEEZE was more effective between all subjects.Conclusions. In agreement with other studies, no single testing position is ideal for every participant. Therefore, it is recommended that investigators employ multiple MVIC positions, when possible, to ensure accuracy. Future research should investigate a variety of gluteus maximus MVIC positions in heterogeneous samples.

  7. Attenuation of eccentric exercise-induced muscle damage conferred by maximal isometric contractions: a mini review

    Directory of Open Access Journals (Sweden)

    Leonardo Coelho Rabello Lima

    2015-10-01

    Full Text Available Although beneficial in determined contexts, eccentric exercise-induced muscle damage (EIMD might be unwanted during training regimens, competitions and daily activities. There are a vast number of studies investigating strategies to attenuate EIMD response after damaging exercise bouts. Many of them consist of performing exercises that induce EIMD, consuming supplements or using equipment that are not accessible for most people. It appears that performing maximal isometric contractions (ISOs 2-4 days prior to damaging bouts promotes significant attenuation of EIMD symptoms that are not related to muscle function. It has been shown that the volume of ISOs, muscle length in which they are performed, and interval between them and the damaging bout influence the magnitude of this protection. Additionally, it appears that this protection is not long-lived, lasting no longer than 4 days. Although no particular mechanisms for these adaptations were identified, professionals should consider applying this non-damaging stimulus before submitting their patients to unaccustomed exercised. However, it seems not to be the best option for athletes or relatively trained individuals. Future studies should focus on establishing if ISOs protect other populations (i.e., trained individuals or muscle groups (i.e., knee extensors against EIMD, as well as investigate different mechanisms for ISO-induced protection.

  8. Isometric Tunnel Placement in Ulnar Collateral Ligament Reconstruction with Single CT Scan

    Directory of Open Access Journals (Sweden)

    Erica Kholinne

    2017-01-01

    Full Text Available Background. Isometric tunnel placement for anterior bundle of the medial collateral ligament (MCL reconstruction is mandatory for successful surgery. Purpose. This study aimed to demonstrate a useful method for identifying isometric tunnel placement using a single computed tomography (CT scan. Study Design. Descriptive Laboratory Study. Methods. Five normal elbows were scanned at 4 different flexion angles at 45° increment. Three-dimensional models were analyzed using 2 different approaches: single and multiple CT scans methods. Ligament footprints in the humerus and the ulna were registered. Ligament length and isometric points were defined. The locations of the isometric points were imported into both methods to be compared. Results. There was no significant difference between 2 methods in calculating the length in every zone. There was also no significant difference in determining isometric ligament’s origin point, which is located approximately 18.2±4.0 mm and 18.4±2.9 mm for single and multiple CT, respectively, measured inferolaterally from medial epicondyle. Conclusions. A solid preoperative plan is critical when predicting tunnel locations due to the difficulty in finding isometric points and the individuality of optimal bone tunnel locations. Using single CT scan, optimal locations can be predicted with the same accuracy as a multiple CT scans with less radiation exposure.

  9. Effect of Metaboreflex on Cardiovascular System in Subjects of Metabolic Syndrome.

    Science.gov (United States)

    Dubey, Pramita; Tiwari, Sunita; Bajpai, Manish; Singh, Kalpana; Jha, Praveen

    2017-07-01

    Metaboreflex is a reflex in which muscle receptors send signals regarding metabolic (metabolites accumulation like lactic acid, potassium, adenosine) conditions of the muscles to nucleus tractus solitarius via afferent III and IV fibres to cause haemodynamic adjustments in order to regulate blood flow on the basis of the status of contracting muscle. Dysregulation in its mechanism in metabolic syndrome is demonstrated. To study the effect of metaboreflex by both isometric and rhythmic handgrip exercise on CVS parameters {Blood Pressure (BP), Cardiac Output (CO) and Systemic Vascular Resistance (SVR)} in subjects of metabolic syndrome. In this study, 27 subjects aged 25 to 45 years were enrolled after ethical clearance and proper consent. They were divided into: a) subjects without metabolic syndrome; and b) subjects with metabolic syndrome. Impedance cardiovasography was done to assess cardiac parameters (systolic and diastolic blood pressure, cardiac output, systemic vascular resistance). Pre-exercise parameters were assessed followed by isometric exercise and post-isometric exercise parameter measurement. Again after rest, rhythmic exercise was followed. Finally post exercise parameters were assessed. Student paired t-test for comparison between pre and post exercise parameters were done. Changes in diastolic BP following exercise were statistically significant in subjects without metabolic syndrome (p-value 0.01 and 0.001 following isometric and rhythmic exercise respectively). In subjects with metabolic syndrome also these changes were significant, but to a lesser extent (p-value 0.1 and 0.01 respectively for isometric and rhythmic exercise). Changes in systolic BP following exercise were statistically significant in subjects without metabolic syndrome (p-value 0.001 and 0.001 following isometric and rhythmic exercise respectively). In subjects with metabolic syndrome also these changes were significant (p-value 0.01 and 0.001 respectively for isometric and

  10. Analysis of maximal isometric force and EMG signal in lower limb exercise. 10.5007/1980-0037.2011v13n6p429

    OpenAIRE

    Cleiton Silva Correa; Bruna Gonçalves Cordeiro da Silva; Cristine Lima Alberton; Eurico Nestor Wilhelm Neto; Antonio Carlos de Moraes; Claudia Silveira Lima; Ronei Silveira Pinto

    2011-01-01

    The aim of this study was to compare maximal isometric force (MIF) and the electrical activity of the vastus medialis, vastus lateralis, rectus femoris, gluteus maximus and biceps femoris long head muscles between maximal voluntary contractions (MVC) performed at different joint angles, and to identify the most suitable positions to normalize the electromyography (EMG) signals from each of these muscles when they are activated under dynamic conditions. Ten men ranging in age from 20 to 30 yea...

  11. Subjectivation and Performative Politics--Butler Thinking Althusser and Foucault: Intelligibility, Agency and the Raced-Nationed-Religioned Subjects of Education

    Science.gov (United States)

    Youdell, Deborah

    2006-01-01

    Judith Butler is perhaps best known for her take-up of the debate between Derrida and Austin over the function of the performative and her subsequent suggestion that the subject be understood as performatively constituted. Another important but less often noted move within Butler's consideration of the processes through which the subject is…

  12. Distraction and task engagement: How interesting and boring information impact driving performance and subjective and physiological responses.

    Science.gov (United States)

    Horrey, William J; Lesch, Mary F; Garabet, Angela; Simmons, Lucinda; Maikala, Rammohan

    2017-01-01

    As more devices and services are integrated into vehicles, drivers face new opportunities to perform additional tasks while driving. While many studies have explored the detrimental effects of varying task demands on driving performance, there has been little attention devoted to tasks that vary in terms of personal interest or investment-a quality we liken to the concept of task engagement. The purpose of this study was to explore the impact of task engagement on driving performance, subjective appraisals of performance and workload, and various physiological measurements. In this study, 31 participants (M = 37 yrs) completed three driving conditions in a driving simulator: listening to boring auditory material; listening to interesting material; and driving with no auditory material. Drivers were simultaneously monitored using near-infrared spectroscopy, heart monitoring and eye tracking systems. Drivers exhibited less variability in lane keeping and headway maintenance for both auditory conditions; however, response times to critical braking events were longer in the interesting audio condition. Drivers also perceived the interesting material to be less demanding and less complex, although the material was objectively matched for difficulty. Drivers showed a reduced concentration of cerebral oxygenated hemoglobin when listening to interesting material, compared to baseline and boring conditions, yet they exhibited superior recognition for this material. The practical implications, from a safety standpoint, are discussed. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Forearm muscle oxygenation during sustained isometric contractions in rock climbers

    Directory of Open Access Journals (Sweden)

    Jan Kodejška

    2016-02-01

    Full Text Available Background. Bouldering and lead climbing are divergent disciplines of the sport of rock climbing. Bouldering moves are short and powerful, whilst sport climbing is longer and require a greater degree of endurance. Aim. The aim of this study was to compare forearm muscle oxygenation during sustained isometric contraction between lead climbers (LC and boulderers (BO. Methods. Eight BO and twelve LC completed maximal finger flexor strength test and sustained contractions to exhaustion at 60% of maximum voluntary contraction (MVC. Differences between BO and LC in maximal strength, time to exhaustion, force time integral (FTI, and tissue oxygenation (SmO2 were assessed by t-test for independent samples. Results. LC showed significantly lower level of average tissue oxygenation (BO 38.9% SmO2, s = 7.4; LC 28.7% SmO2, s = 7.1 and maximal tissue deoxygenation (BO 25.6% SmO2, s = 8.2; LC 13.5% SmO2, s = 8.5. LC demonstrated significantly lower finger flexor strength (519 N, s = 72 than BO (621 N, s = 142. LC sustained a longer time of contraction (not significantly (BO 52.2 s, s = 11.5; LC 60.6 s, s = 13 and achieved a similar value of FTI (BO 17421 Ns, s = 4291; LO 17476 Ns, s = 5036 in the endurance test. Conclusions. The results showed lower deoxygenation during sustained contraction in BO than LC despite similar FTI, indicating different local metabolic pathways in both groups.

  14. Comparison of the perceived subjective exertion and total load lifted response in resistance exercises performed on stable and unstable platforms

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    Liliane Cunha Aranda

    2015-03-01

    Full Text Available This study aimed to compare the perceived subjective exertion (PSE and total load lifted in resistance exercises performed on stable platforms (SP and unstable platforms (UP. Participants were 20 men (24.6 ± 3.4 years, 179 ± 0.1 cm, 80.6 ± 9.1 kg and 11.8 ± 3.4% fat. Each subject performed a 15 maximum repetition test in half squat exercises (soil and balance discs, pronated barbell row (soil and bosu and biceps curl (soil and balance discs in both conditions. PSE was measured using the OMNI-RES scale and the load lifted value (kg. To verify the normality of data, the Shapiro-Wilk test was used. Possible differences related to loads and PSE on the platforms were performed by the paired t test. Significance level of p <0.05 was adopted. No significant differences between PSE values on SP and UP were respectively observed in the half squat (8.2 and 8.5 / p = 0.8, pronated barbell row (8.4 and 8.4 / p = 0.7 and biceps curl (8.6 and 8.7 / p = 1.0. Higher load values on SP and UP were respectively found in half squat (83.9kg and 70.3kg / p <0.001 and pronated barbell row exercises (53.2kg and 48.6kg / p = 0.01 on SP. However, biceps curl showed dissimilar behavior (48.2kg and 47.4kg / p = 0.5. It was concluded that UP does not promote differences in PSE responses even working with smaller load or similar load.

  15. INFLUENCE OF TYPE OF MUSCLE CONTRACTION AND GENDER ON POSTACTIVATION POTENTIATION OF UPPER AND LOWER LIMB EXPLOSIVE PERFORMANCE IN ELITE FENCERS

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    Charilaos Tsolakis

    2011-09-01

    Full Text Available The purpose of this study was to evaluate the postactivation potentiation (PAP effect of isometric and plyometric contractions on explosive performance of the upper and the lower limbs in male and female elite athletes. Thirteen male and ten female international level fencers performed four protocols of either isometric (3 sets of 3 sec or plyometric (3 sets of 5 repetitions bench and leg press, in a within subject randomized design. Before and immediately after the PAP treatment and following 4, 8, 12 min, explosive performance was measured by performing a countermovement jump (CMJ or a bench press throw. Statistical analysis revealed significant time effect for peak leg power during the CMJ (p < 0.001 only for men, with values after the isometric PAP treatment being lower than baseline at the 8 and 12 min time points (by 7.5% (CI95% = 3.9-11.2% and 8.7% (CI95% = 6.0-11.5%, respectively, while after the plyometric PAP treatment peak leg power remained unchanged. A significant negative correlation was found between leg strength (as expressed by 1-RM leg press performance and the change in peak leg power between baseline and after 12 min of recovery only in male fencers (r = -0.55, p < 0.05, suggesting that stronger individuals may show a greater decrease in peak leg power. Based on the above results we conclude that lower body power performance in international level fencers may be negatively affected after isometric contractions and thus they should be advised against using isometric exercises to induce PAP with the protocol prescribed in the present study. Furthermore, gender and strength level must be considered in the practical application of PAP

  16. When does stress help or harm? The effects of stress controllability and subjective stress response on Stroop performance.

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    Roselinde Kaiser Henderson

    2012-06-01

    Full Text Available The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing to clinical therapy. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, research suggests that the impact of stress on cognitive functioning depends on an individual’s response to stressors: moderate responses to stress can lead to improved performance while extreme (high or low responses can lead to impaired performance. The present studies tested the hypothesis that 1 learning to behaviorally control stressors leads to improved performance on a test of general executive functioning, the color-word Stroop, and that 2 this improvement emerges specifically for people who report moderate (subjective responses to stress. Experiment 1: Stroop performance, measured before and after a stress manipulation, was compared across groups of undergraduate participants (n=109. People who learned to control a noise stressor and received accurate performance feedback demonstrated reduced Stroop interference compared with people exposed to uncontrollable noise stress and feedback indicating an exaggerated rate of failure. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest reduction in Stroop interference. In contrast, in the group exposed to uncontrollable events, self-reported stress failed to predict performance. Experiment 2: In a second sample (n=90, we specifically investigated the role of controllability by keeping the rate of failure feedback constant across groups. In the group who learned behavioral control, those who reported moderate levels of stress

  17. Analysis of Tests Evaluating Sport Climbers’ Strength and Isometric Endurance

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    Ozimek Mariusz

    2016-12-01

    Full Text Available The present study was designed to determine which types of specific tests provide an effective evaluation of strength and endurance in highly trained competitive sport climbers. The research process consisted of three basic components: the measurement of selected somatic characteristics of the climbers, the assessment of their physical conditioning, and a search for correlations between the anthropometric and “conditioning” variables on the one hand, and climber’s performance on the other. The sample of subjects consisted of 14 experienced volunteer climbers capable of handling 7a- 8a+/b on-sight rock climbing grades. The strongest correlations (Spearman’s rank were found between climber’s competence and the relative results of the finger strength test (r = 0.7; much lower, but still statistically significant coefficients were found between the level of competence and the results of the muscle endurance tests (r = 0.53 – 0.57. Climbers aspiring to attain an elite level must have strong finger and forearm muscles, but most of all, they must be capable of releasing their potential during specific motor capability tests engaging these parts of the body. The forearm muscles of elite climbers must also be very resistant to fatigue. Since highly trained athletes vary only slightly in body mass, this variable does not have a major effect on their performance during strength and endurance tests.

  18. A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions

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    Nurhazimah Nazmi

    2016-08-01

    Full Text Available In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

  19. A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions

    Science.gov (United States)

    Nazmi, Nurhazimah; Abdul Rahman, Mohd Azizi; Yamamoto, Shin-Ichiroh; Ahmad, Siti Anom; Zamzuri, Hairi; Mazlan, Saiful Amri

    2016-01-01

    In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI) applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG) beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF) of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above. PMID:27548165

  20. Analysis of muscle fatigue induced by isometric vibration exercise at varying frequencies.

    Science.gov (United States)

    Mischi, M; Rabotti, C; Cardinale, M

    2012-01-01

    An increase in neuromuscular activity, measured by electromyography (EMG), is usually observed during vibration exercise. The underlying mechanisms are however unclear, limiting the possibilities to introduce and exploit vibration training in rehabilitation programs. In this study, a new training device is used to perform vibration exercise at varying frequency and force, therefore enabling the analysis of the relationship between vibration frequency and muscle fatigue. Fatigue is estimated by maximum voluntary contraction measurement, as well as by EMG mean-frequency and conduction-velocity analysis. Seven volunteers performed five isometric contractions of the biceps brachii with a load consisting of a baseline of 80% of their maximum voluntary contraction (MVC), with no vibration and with a superimposed 20, 30, 40, and 50 Hz vibrational force of 40 N. Myoelectric and mechanical fatigue were estimated by EMG analysis and by assessment of the MVC decay, respectively. A dedicated motion artifact canceler, making use of accelerometry, is proposed to enable accurate EMG analysis. Use of this canceler leads to better interpolation of myoelectric fatigue trends and to better correlation between mechanical and myoelectric fatigue. In general, our results suggest vibration at 30 Hz to be the most fatiguing exercise. These results contribute to the analysis of vibration exercise and motivate further research aiming at improved training protocols.

  1. Normalizing shoulder EMG: An optimal set of maximum isometric voluntary contraction tests considering reproducibility.

    Science.gov (United States)

    Schwartz, Cédric; Tubez, François; Wang, François-Charles; Croisier, Jean-Louis; Brüls, Olivier; Denoël, Vincent; Forthomme, Bénédicte

    2017-08-18

    Normalization of the electromyography (EMG) signal is often performed relatively to maximal voluntary activations (MVA) obtained during maximum isometric voluntary contraction (MVIC). The first aim was to provide an inter-session reproducible protocol to normalize the signal of eight shoulder muscles. The protocol should also lead to a level of activation >90% of MVA for >90% of the volunteers. The second aim was to evaluate the influence of the method used to extract the MVA from the EMG envelope on the normalized EMG signal. Thirteen volunteers performed 12 MVICs twice (one week interval). Several time constants (100ms to 2s) were compared when extracting the MVA from the EMG envelope. The EMG activity was also acquired during an arm elevation. Our results show that a combination of nine MVIC tests was required to meet our requirements including reproducibility. Both the number of MVIC tests and the size of the time constant influence the normalized EMG signal during the dynamic activity (variations up to 15%). A time constant of 1s was a good compromise to extract the MVA. These findings are valuable to improve the reproducibility of EMG signal normalization. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Electromyographic assessment of muscle fatigue during isometric vibration training at varying frequencies.

    Science.gov (United States)

    Mischi, M; Rabotti, C; Cardinale, M

    2010-01-01

    Resistance exercise is essential to improve or maintain muscle performance. Vibration training has been suggested as an alternative option for muscle conditioning, aiming especially at improving muscle strength and power. Several studies link the effects of vibration training to enhanced neuromuscular stimulation, measured by electromyography (EMG) and typically ascribed to involuntary reflex mechanisms. However, the underlying mechanisms are still unclear, limiting the use of vibration training. This paper proposes additional methods to analyze the mechanisms involved in vibration training. A dedicated measurement setup was realized to relate vibration parameters to muscle fatigue in the biceps brachii. Fatigue is estimated by EMG mean frequency and conduction velocity assessments as well as by maximum voluntary contraction (MVC) force measurements. A modified maximum likelihood algorithm is proposed for the conduction velocity estimation based on high-density EMG recording. Five volunteers performed four isometric contractions of 50 s at 80% MVC with no vibration (control) and with superimposed vibration at 20, 30, and 40 Hz. Fatigue was estimated from the decay of force, EMG mean frequency, and EMG conduction velocity. 30-Hz vibrations represented the most fatiguing stimulus. Our preliminary results also show a better correlation between force and conduction velocity decay than between force and mean frequency decay, indicating the former as a better EMG indicator of fatigue. The proposed methods provide important advancements for the analysis of vibration exercise and guidance towards the definition of optimal training protocols.

  3. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting.

    Science.gov (United States)

    Singh, Rabindarjeet; Hwa, Ooi Cheong; Roy, Jolly; Jin, Chai Wen; Ismail, Siti Musyrifah; Lan, Mohamad Faizal; Hiong, Loo Lean; Aziz, Abdul-Rashid

    2011-09-01

    To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month. Seven hundred and thirty-four (411 male and 323 female) Malaysian Junior-level Muslim athletes (mean age 16.3 ± 2.6 y) participated in the survey which was designed to establish the personal perception of their sport performance, sleep pattern, food and fluid intake during Ramadan fasting. The survey was conducted during and immediately after the month of Ramadan in 2009. Twenty-four percent of the athletes perceived that there was an adverse effect of the Ramadan fast on their sporting performance and 29.3% reported that quality of training during Ramadan was also negatively influenced. Majority (48.2%) of the athletes stated that Ramadan fasting did not affect their normal sleep pattern but 66.6% of them complained of sleepiness during the daytime. Half of the athletes (41.4%) maintained the caloric intake during Ramadan as they normally would with the majority of them (76.2%) reporting that they consumed more fluids during Ramadan. Overall, Malaysian Junior-level Muslim athletes showed diverse views in their perception of changes in their training, sleep and dietary patterns during Ramadan fast. These individual differences probably indicate differences in the athletes' adaptability and coping strategies during fasting and training in Ramadan.

  4. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting

    Science.gov (United States)

    Singh, Rabindarjeet; Hwa, Ooi Cheong; Roy, Jolly; Jin, Chai Wen; Ismail, Siti Musyrifah; Lan, Mohamad Faizal; Hiong, Loo Lean; Aziz, Abdul-Rashid

    2011-01-01

    Purpose To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month. Methods Seven hundred and thirty-four (411 male and 323 female) Malaysian Junior-level Muslim athletes (mean age 16.3 ± 2.6 y) participated in the survey which was designed to establish the personal perception of their sport performance, sleep pattern, food and fluid intake during Ramadan fasting. The survey was conducted during and immediately after the month of Ramadan in 2009. Results Twenty-four percent of the athletes perceived that there was an adverse effect of the Ramadan fast on their sporting performance and 29.3% reported that quality of training during Ramadan was also negatively influenced. Majority (48.2%) of the athletes stated that Ramadan fasting did not affect their normal sleep pattern but 66.6% of them complained of sleepiness during the daytime. Half of the athletes (41.4%) maintained the caloric intake during Ramadan as they normally would with the majority of them (76.2%) reporting that they consumed more fluids during Ramadan. Conclusions Overall, Malaysian Junior-level Muslim athletes showed diverse views in their perception of changes in their training, sleep and dietary patterns during Ramadan fast. These individual differences probably indicate differences in the athletes’ adaptability and coping strategies during fasting and training in Ramadan. PMID:22375236

  5. “How many sums can I do”? Performative strategies and diffractive thinking as methodological tools for rethinking mathematical subjectivity

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    Anna Palmer

    2011-12-01

    Full Text Available The aim of this article is to illustrate how the understanding of mathematical subjectivity changes when transiting theoretically and methodologically from a discursive and performative thinking, as suggested by Judith Butler (1990, 1993, 1997, to an agential realist and diffractive thinking, inspired by Karen Barad’s theories (2007, 2008. To show this I have examined narrative memory stories about mathematics written by students participating in Teacher Education maths courses. I provide examples of such stories and present an in-depth analysis of one such story. The first part of the analysis has been carried out using performative methodological strategies – in relation to Judith Butler’s theories – while the latter part of analysis has been performed with the aid of diffractive methodological thinking – in relation to Barad’s theoretical perspectives. When summarising the different analyses, it becomes evident that the understanding of data – and of me as researcher – changes when transiting from one theoretical and methodological arena to another. Depending on which questions we pose, what methodological strategies we use, and which theoretical fields we get involved in, we would see and understand this differently.

  6. Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

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    Jaeyoung Song

    2017-11-01

    Full Text Available Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from external sources (e.g., vehicles make securing durable waterproofing challenging. While ASTM Guides, Korean Codes, and BS Practice Codes on below-grade waterproofing stress the importance of manufacturer specification for quality control, ensuring high quality waterproofing for the ever-changing scale of construction remains a challenge. This study proposes a new evaluation method and criteria which allow for the selection of waterproofing membranes based on specific performance attributes and workmanship. It subjects six different waterproofing membrane systems (installed on dry and wet surface conditioned mortar slab specimens with an artificial joint to different cyclic movement widths to 300 cycles in water to demonstrate that inadequate material properties and workmanship are key causes for leakages.

  7. Neurocognitive performance, subjective well-being, and psychosocial functioning after benzodiazepine withdrawal in patients with schizophrenia or bipolar disorder

    DEFF Research Database (Denmark)

    Baandrup, Lone; Fagerlund, Birgitte; Glenthoj, Birte

    2017-01-01

    Chronic benzodiazepine use is common in patients with mental illness and is associated with cognitive impairment. It is unclear whether benzodiazepine-induced cognitive impairment is reversible. Amelioration of cognitive dysfunction may be facilitated during benzodiazepine tapering by add......-on melatonin due to its anti-inflammatory and neuroprotective properties. We examined how melatonin and benzodiazepine withdrawal affect cognition, subjective well-being, and psychosocial functioning. Eighty patients with schizophrenia or bipolar disorder were randomized to add-on treatment once daily...... with either prolonged-release melatonin or placebo in a 24-week, double-blind clinical trial. All participants gradually tapered usual benzodiazepine dosage in a closely monitored treatment setting. We used the Brief Assessment of Cognition in Schizophrenia (BACS) to assess neurocognitive performance...

  8. Eccentric and Isometric Hip Adduction Strength in Male Soccer Players With and Without Adductor-Related Groin Pain An Assessor-Blinded Comparison

    DEFF Research Database (Denmark)

    Thorborg, Kristian; Branci, Sonia; Nielsen, Peter Martin

    2014-01-01

    BACKGROUND: Adductor-related pain is the most common clinical finding in soccer players with groin pain and can be a long-standing problem affecting physical function and performance. Hip adductor weakness has been suggested to be associated with this clinical entity, although it has never been...... investigated. PURPOSE: To investigate whether isometric and eccentric hip strength are decreased in soccer players with adductor-related groin pain compared with asymptomatic soccer controls. The hypothesis was that players with adductor-related groin pain would have lower isometric and eccentric hip adduction...... strength than players without adductor-related groin pain. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Male elite and subelite players from 40 teams were contacted. In total, 28 soccer players with adductor-related groin pain and 16 soccer players without adductor-related groin pain...

  9. Muscle shear elastic modulus is linearly related to muscle torque over the entire range of isometric contraction intensity.

    Science.gov (United States)

    Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine

    2015-08-01

    Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Optimal Normalization Tests for Muscle Activation of the Levator Scapulae, Pectoralis Minor, and Rhomboid Major: An Electromyography Study Using Maximum Voluntary Isometric Contractions.

    Science.gov (United States)

    Castelein, Birgit; Cagnie, Barbara; Parlevliet, Thierry; Danneels, Lieven; Cools, Ann

    2015-10-01

    To identify maximum voluntary isometric contraction (MVIC) test positions for the deeper-lying scapulothoracic muscles (ie, levator scapulae, pectoralis minor, rhomboid major), and to provide a standard set of a limited number of test positions that generate an MVIC in all scapulothoracic muscles. Cross-sectional study. Physical and rehabilitation medicine department. Healthy subjects (N=21). Not applicable. Mean peak electromyographic activity from levator scapulae, pectoralis minor, and rhomboid major (investigated with fine-wire electromyography) and from upper trapezius, middle trapezius, lower trapezius, and serratus anterior (investigated with surface electromyography) during the performance of 12 different MVICs. The results indicated that various test positions generated similar high mean electromyographic activity and that no single test generated maximum activity for a specific muscle in all subjects. The results of this study support using a series of test positions for normalization procedures rather than a single exercise to increase the likelihood of recruiting the highest activity in the scapulothoracic muscles. A standard set of 5 test positions was identified as being sufficient for generating an MVIC of all scapulothoracic muscles: seated T, seated U 135°, prone T-thumbs up, prone V-thumbs up, and supine V-thumbs up. A standard set of test positions for normalization of scapulothoracic electromyographic data that also incorporates the levator scapulae, pectoralis minor, and rhomboid major muscles is 1 step toward a more comprehensive understanding of normal and abnormal muscle function of these muscles and will help to standardize the presentation of scapulothoracic electromyographic muscle activity. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  11. The antihypertensive effects of aerobic versus isometric handgrip resistance exercise.

    Science.gov (United States)

    Ash, Garrett I; Taylor, Beth A; Thompson, Paul D; MacDonald, Hayley V; Lamberti, Lauren; Chen, Ming-Hui; Farinatti, Paulo; Kraemer, William J; Panza, Gregory A; Zaleski, Amanda L; Deshpande, Ved; Ballard, Kevin D; Mujtaba, Mohammadtokir; White, C Michael; Pescatello, Linda S

    2017-02-01

    Aerobic exercise reduces blood pressure (BP) on average 5-7 mmHg among those with hypertension; limited evidence suggests similar or even greater BP benefits may result from isometric handgrip (IHG) resistance exercise. We conducted a randomized controlled trial investigating the antihypertensive effects of an acute bout of aerobic compared with IHG exercise in the same individuals. Middle-aged adults (n = 27) with prehypertension and obesity randomly completed three experiments: aerobic (60% peak oxygen uptake, 30 min); IHG (30% maximum voluntary contraction, 4 × 2 min bilateral); and nonexercise control. Study participants were assessed for carotid-femoral pulse wave velocity pre and post exercise, and left the laboratory wearing an ambulatory BP monitor. SBP and DBP were lower after aerobic versus IHG (4.8 ± 1.8/3.1 ± 1.3 mmHg, P = 0.01/0.04) and control (5.6 ± 1.8/3.6 ± 1.3 mmHg, P = 0.02/0.04) over the awake hours, with no difference between IHG versus control (P = 0.80/0.83). Pulse wave velocity changes following acute exercise did not differ by modality (aerobic increased 0.01 ± 0.21 ms, IHG decreased 0.06 ± 0.15 ms, control increased 0.25 ± 0.17 ms, P > 0.05). A subset of participants then completed either 8 weeks of aerobic or IHG training. Awake SBP was lower after versus before aerobic training (7.6 ± 3.1 mmHg, P = 0.02), whereas sleep DBP was higher after IHG training (7.7 ± 2.3 mmHg, P = 0.02). Our findings did not support IHG as antihypertensive therapy but that aerobic exercise should continue to be recommended as the primary exercise modality for its immediate and sustained BP benefits.

  12. Digital Dynamometer and Goniometer in Analyzing Isometric Capacities and Tennis Serving

    Directory of Open Access Journals (Sweden)

    Liu Chia-Che

    2016-01-01

    Full Text Available The study was to investigate relation between tennis serving techniques and shoulder joint muscles in various skilled players in Taiwan. The study used Micro FET3 (Digital Manual Muscle Dynamometer and Goniometer which appraised the isometric capacity of the shoulder joint and perimeter muscle. The research consists of 13 collegiate male tennis players; 6 players were in elite groups and the other 7 players were in general groups. The tennis players performed 30 servers testing the range to appraise serve technique reflect. The application of t-test and Linear Regression analyzed the serve technique reflect interrelated with the shoulder joint muscle. The muscle strength and the serve accuracy predominate interrelated place where middle trapezius, shoulder internal rotator, and shoulder external rotator of favor hands were obvious. The muscle strength and the serve speed predominated interrelated place where shoulder internal rotator and shoulder external rotator of favor hands were obvious. This study also discovered triceps of favor hands, shoulder extensor, shoulder abductor, triceps, and middle trapezius of non- favor hands muscle strength didn't have any outstanding reference with tennis league table. The research confirmed that the shoulder joint muscle discipline increased shoulder internal rotator, shoulder external rotator, and middle trapezius that help the serve technique reflect.

  13. Type 2 diabetes mellitus patients manifest characteristic spatial EMG potential distribution pattern during sustained isometric contraction.

    Science.gov (United States)

    Watanabe, Kohei; Miyamoto, Toshiaki; Tanaka, Yoji; Fukuda, Kazuhito; Moritani, Toshio

    2012-09-01

    The purpose of the present study is to investigate spatial surface electromyography (SEMG) potential distribution pattern in type 2 diabetes mellitus (T2DM) patients. Nine T2DM patients and nine age-matched healthy men (CON) performed a sustained isometric knee extension at 10% of maximal voluntary contraction for 120s. Multi-channel SEMG was recorded from the vastus lateralis muscle by means of 64 electrodes. To characterize spatial SEMG potential distribution pattern, modified entropy and correlation coefficients between same electrode locations were calculated at 15, 60 and 120s for the root mean square values. At 60 and 120s, modified entropy in T2DM was significantly lower than those in CON (p<0.05). Correlation coefficients for T2DM were significantly higher than those for CON at 60 and 120s (p<0.05). From these results, we suggested that T2DM patients continue to recruit limited and same motor units during the sustained contraction at low force level. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  14. Effects of zeolite supplementation on parameters of intestinal barrier integrity, inflammation, redoxbiology and performance in aerobically trained subjects.

    Science.gov (United States)

    Lamprecht, Manfred; Bogner, Simon; Steinbauer, Kurt; Schuetz, Burkhard; Greilberger, Joachim F; Leber, Bettina; Wagner, Bernhard; Zinser, Erwin; Petek, Thomas; Wallner-Liebmann, Sandra; Oberwinkler, Tanja; Bachl, Norbert; Schippinger, Gert

    2015-01-01

    Zeolites are crystalline compounds with microporous structures of Si-tetrahedrons. In the gut, these silicates could act as adsorbents, ion-exchangers, catalysts, detergents or anti-diarrheic agents. This study evaluated whether zeolite supplementation affects biomarkers of intestinal wall permeability and parameters of oxidation and inflammation in aerobically trained individuals, and whether it could improve their performance. In a randomized, double-blinded, placebo controlled trial, 52 endurance trained men and women, similar in body fat, non-smokers, 20-50 years, received 1.85 g of zeolite per day for 12 weeks. Stool samples for determination of intestinal wall integrity biomarkers were collected. From blood, markers of redox biology, inflammation, and DNA damage were determined at the beginning and the end of the study. In addition, VO2max and maximum performance were evaluated at baseline and after 12 weeks of treatment. For statistical analyses a 2-factor ANOVA was used. At baseline both groups showed slightly increased stool zonulin concentrations above normal. After 12 weeks with zeolite zonulin was significantly (p zeolite group. There were no significant changes observed in the other measured parameters. Twelve weeks of zeolite supplementation exerted beneficial effects on intestinal wall integrity as indicated via decreased concentrations of the tight junction modulator zonulin. This was accompanied by mild anti-inflammatory effects in this cohort of aerobically trained subjects. Further research is needed to explore mechanistic explanations for the observations in this study.

  15. Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings.

    Science.gov (United States)

    Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

    2015-12-01

    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p instructional design research are discussed.

  16. How academic career and habits related to the school environment influence on academic performance in the physical education subject

    Directory of Open Access Journals (Sweden)

    Vizuete Carrizosa, Manuel

    2012-01-01

    Full Text Available The main objective of this study was to analyze the degree of influence of some school habits and scholar trayectory on academic achievement in physical education (PE students in secondary education (ESO in the city of Badajoz. A total sample of 1197 students in compulsory secondary education 49.9% men, and 50.1% women, participated in the study. They spent a questionnaire filled out by the river questions about major school habits, of which eight variables were analyzed also included the final course in the subject of EF as a variable for analysis of academic performance. Through statistical analysis with ANOVA, Mann-Whitney U, and Kruskal Wallis H, there are significant differences in PE scores in all variables analyzed (p d».001, among which being repetitive, being truant, the time to read and study daily. In the variable environment perceived in class, there is a degree of significance (p d».05. Pupils who were repeaters, missing more classes or were delayed more times than read and studied less and earned a worse environment in their classes, are those who obtained poorer performance on EF.

  17. Objective and subjective evaluation of the performance of medical contact lenses fitted using a contact lens selection algorithm.

    Science.gov (United States)

    Visser, Esther-Simone; Wisse, Robert P L; Soeters, Nienke; Imhof, Saskia M; Van der Lelij, Allegonda

    2016-08-01

    To evaluate the performance of medical contact lenses (CLs) for a wide range of clinical indications. Prospective cross-sectional study. A total of 281 eyes were evaluated in 281 consecutive patients (≥18 years of age; CL use ≥3 months) who visited the contact lens service in a tertiary academic clinic for a scheduled follow-up visit. The main outcome measured were clinical indications for CL wear; CL type; change in corrected distance visual acuity (CDVA) with CL use; CL wearing duration; CL wearing time; subjective performance measured using a visual analog scale (VAS) questionnaire (score range: 0-100); and effectiveness of the lens-selection algorithm. Wearing CLs significantly improved CDVA compared to wearing spectacles (median change: -0.15 logMAR, range: 1.00 to -2.10; Plenses and users of soft lenses. These results underscore the importance of prescribing scleral lenses and the need for tertiary eye clinics to offer patients a variety of CL types. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  18. A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia.

    Science.gov (United States)

    McKenna, Victoria S; Zhang, Bin; Haines, Morgan B; Kelchner, Lisa N

    2017-05-17

    This systematic review summarizes the effects of isometric lingual strength training on lingual strength and swallow function in adult populations. Furthermore, it evaluates the designs of the reviewed studies and identifies areas of future research in isometric lingual strength training for dysphagia remediation. A comprehensive literature search of 3 databases and additional backward citation search identified 10 studies for inclusion in the review. The review reports and discusses the isometric-exercise intervention protocols, pre- and postintervention lingual-pressure data (maximum peak pressures and lingual-palatal pressures during swallowing), and oropharyngeal swallowing measures such as penetration-aspiration scales, oropharyngeal residue and duration, lingual volumes, and quality-of-life assessments. Studies reported gains in maximum peak lingual pressures following isometric lingual strength training for both healthy adults and select groups of individuals with dysphagia. However, due to the variability in study designs, it remains unclear whether strength gains generalize to swallow function. Although isometric lingual strength training is a promising intervention for oropharyngeal dysphagia, the current literature is too variable to confidently report specific therapeutic benefits. Future investigations should target homogenous patient populations and use randomized controlled trials to determine the efficacy of this treatment for individuals with dysphagia.

  19. Relationship between lower extremity isometric muscle strength and standing balance in patients with multiple sclerosis.

    Science.gov (United States)

    Citaker, Seyit; Guclu-Gunduz, Arzu; Yazici, Gokhan; Bayraktar, Deniz; Nazliel, Bijen; Irkec, Ceyla

    2013-01-01

    Muscle strength and standing balance decrease in patients with Multiple Sclerosis (MS). The aim of the present study was to investigate the relationship between the lower extremity isometric muscle strength and standing balance in patients with MS. Forty-seven patients with MS and 10 healthy volunteers were included. Neurological disability level was assessed using Expanded Disability Status Scale (EDSS). Isometric strength of seven lower extremity muscles (hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor) was assessed using hand-held dynamometer. Duration of static one-leg standing balance was measured using digital chronometer. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength, and duration of one-leg standing balance were decreased in patients with MS when compared with controls (p leg standing balance in patients with MS. All assessed lower extremity isometric muscle strength (except ankle dorsal flexor) was related with EDSS. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength decreases in ambulatory MS patients. Lower extremity muscle weakness and neurological disability level are related with imbalance in MS population. Hip and knee region muscles weakness increases the neurological disability level. For the better balance and decrease neurological disability level whole lower extremity muscle strengthening should be included in rehabilitation programs.

  20. Psychomotor performance in relation to acute oral administration of Delta9-tetrahydrocannabinol and standardized cannabis extract in healthy human subjects.

    Science.gov (United States)

    Roser, Patrik; Gallinat, Jürgen; Weinberg, Gordon; Juckel, Georg; Gorynia, Inge; Stadelmann, Andreas M

    2009-08-01

    Abnormalities in psychomotor performance are a consistent finding in schizophrenic patients as well as in chronic cannabis users. The high levels of central cannabinoid (CB(1)) receptors in the basal ganglia, the cerebral cortex and the cerebellum indicate their implication in the regulation of motor activity. Based on the close relationship between cannabis use, the endogenous cannabinoid system and motor disturbances found in schizophrenia, we expected that administration of cannabinoids may change pattern of psychomotor activity like in schizophrenic patients. This prospective, double-blind, placebo-controlled cross-over study investigated the acute effects of cannabinoids on psychomotor performance in 24 healthy right-handed volunteers (age 27.9 +/- 2.9 years, 12 male) by comparing Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and standardized cannabis extract containing Delta(9)-THC and cannabidiol. Psychomotor performance was assessed by using a finger tapping test series. Cannabis extract, but not Delta(9)-THC, revealed a significant reduction of right-hand tapping frequencies that was also found in schizophrenia. As to the pure Delta(9)-THC condition, left-hand tapping frequencies were correlated with the plasma concentrations of the Delta(9)-THC metabolite 11-OH-THC. These effects are thought to be related to cannabinoid actions on CB(1) receptors in the basal ganglia, the cerebral cortex and the cerebellum. Our data further demonstrate that acute CB(1) receptor activation under the cannabis extract condition may also affect intermanual coordination (IMC) as an index of interhemispheric transfer. AIR-Scale scores as a measure of subjective perception of intoxication were dose-dependently related to IMC which was shown by an inverted U-curve. This result may be due to functional changes involving GABAergic and glutamatergic neurotransmission within the corpus callosum.

  1. Differences in cervical multifidus muscle thickness during isometric contraction of shoulder muscles: a comparison between patients with chronic neck pain and healthy controls.

    Science.gov (United States)

    Rahnama, Leila; Rezasoltani, Asghar; Zavieh, Minoo Khalkhali; NooriKochi, Farhang; Baghban, Alireza Akbarzadeh

    2015-01-01

    The purposes of this study were to (1) measure the thickness of cervical multifidus muscle (CMM) in different maximal voluntary contraction percentages of isometric contraction of shoulder muscles, (2) evaluate the differences of the CMM thickness in different directions of the shoulder movement, and (3) compare the changes in the CMM thickness of participants with neck pain and also of healthy individuals. Twenty healthy men (age, 27.45 ± 4.37 years; height, 177 ± 4.66 cm; weight, 72.85 ± 6.46 kg) and 20 men with chronic mechanical neck pain (age, 28.90 ± 5.53 years; height, 176 ± 5.98 cm; weight, 73.15 ± 7.82 kg) participated in the study. Both the right and left CMM thicknesses were measured using an ultrasound device while participants performed isometric contraction of shoulder muscles in 6 movement directions. In both groups, an increment of CMM thickness followed as the increase of isometric force (P pain participants (P = .03). Although no significant difference of CMM thickness was seen among the effects of the 6 force directions (P > .05), there was a significant difference of activity noted between the left and right sides (P = .047). The results of the present study indicate that isometric contraction of shoulder muscles caused an increase in the CMM thickness regardless of force direction. This increase was seen in both groups of healthy participants and patients with neck pain. However, less thickness changes were observed in participants with neck pain, which may be interpreted as reduced CMM activity in such people. Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.

  2. Influence of obstructive sleep apnea syndrome in the fluctuation of the submaximal isometric torque of knee extensors in patients with early-grade osteoarthritis

    Science.gov (United States)

    Silva, Andressa; Mello, Marco T.; Serrão, Paula R.; Luz, Roberta P.; Bittencourt, Lia R.; Mattiello, Stela M.

    2015-01-01

    OBJECTIVE: The aim of this study was to investigate whether obstructive sleep apnea (OSA) alters the fluctuation of submaximal isometric torque of the knee extensors in patients with early-grade osteoarthritis (OA). METHOD: The study included 60 male volunteers, aged 40 to 70 years, divided into four groups: Group 1 (G1) - Control (n=15): without OA and without OSA; Group 2 (G2) (n=15): with OA and without OSA; Group 3 (G3) (n=15): without OA and with OSA; and Group 4 (G4) (n=15) with OA and with OSA. Five patients underwent maximal isometric contractions of 10 seconds duration each, with the knee at 60° of flexion to determine peak torque at 60°. To evaluate the fluctuation of torque, 5 submaximal isometric contractions (50% of maximum peak torque) of 10 seconds each, which were calculated from the standard deviation of torque and coefficient of variation, were performed. RESULTS: Significant differences were observed between groups for maximum peak torque, while G4 showed a lower value compared with G1 (p=0.005). Additionally, for the average torque exerted, G4 showed a lower value compared to the G1 (p=0.036). However, no differences were found between the groups for the standard deviation (p=0.844) and the coefficient of variation (p=0.143). CONCLUSION: The authors concluded that OSA did not change the parameters of the fluctuation of isometric submaximal torque of knee extensors in patients with early-grade OA. PMID:26443974

  3. The responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact sound: a pilot study

    National Research Council Canada - National Science Library

    Seok Hyeon Yun; Sang Jin Park; Chang Sun Sim; Joo Hyun Sung; Ahra Kim; Jang Myeong Lee; Sang Hyun Lee; Jiho Lee

    2017-01-01

    ...) may have the different effects on the human’s body and mind. The purpose of this study is to assess the responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact...

  4. Effects of one-night sleep deprivation on selective attention and isometric force in adolescent karate athletes.

    Science.gov (United States)

    Ben Cheikh, Ridha; Latiri, Imed; Dogui, Mohamed; Ben Saad, Helmi

    2017-06-01

    Most of the available literature related to aspects of sleep deprivation is primarily focused on memory and learning, and studies regarding its effects on selective attention and/or physical performance are scarce. Moreover, the available literature includes general population or people involved in team sports (e.g. volleyball). However, only few studies were performed on athletes involved in combat sports (e.g. karate). The aim of the present study was to determine the effects of a total one-night sleep deprivation (1NSD) on activation and inhibition processes of selective attention and on maximal isometric force in karate athletes. Twelve young karate athletes (mean age 16.9±0.8 years) were enrolled. The protocol consists of two successive sessions: a normal night's sleep (NNS) and a total 1NSD. After each night, athletes performed selective attention and muscle strength tests during the same following three times (T) of the day: T1NNS or T11NSD: 8-9 a.m.; T2NNS or T21NSD: 12 a.m.-1 p.m.; T3NNS or T31NSD: 4-5 p.m. Activation (simple [SRT] and choice reaction times [CRT]) and inhibition (negative priming) processes were evaluated using Superlab v. 4.5 software (Cedrus Corporation, San Pedro, CA, USA). Maximal force and maximal force time (MFT) of brachial biceps isometric contraction were evaluated (Ergo System®, Globus, Codognè, Italy). A non-parametric test was used to evaluate the sessions (NNS vs. SND for the same time period) and time (T1NNS vs. 1NSD) effects. All athletes completed all tests after a NNS. Twelve, eleven and four athletes completed all tests at T11NSD, T21NSD and T31NSD, respectively. As for sessions effects, no statistically significant difference was found. As for time effects, a significant increase in SRT at T21NSD vs. T1NNS (345±47 vs. 317±33 ms, respectively), a significant increase in MFT at T21NSD vs. T1NNS (2172±260 vs.1885±292 ms, respectively), and no significant changes in CRT and negative priming reaction time or MFT data

  5. Loss of knee extensor torque complexity during fatiguing isometric muscle contractions occurs exclusively above the critical torque.

    Science.gov (United States)

    Pethick, Jamie; Winter, Samantha L; Burnley, Mark

    2016-06-01

    The complexity of knee extensor torque time series decreases during fatiguing isometric muscle contractions. We hypothesized that because of peripheral fatigue, this loss of torque complexity would occur exclusively during contractions above the critical torque (CT). Nine healthy participants performed isometric knee extension exercise (6 s of contraction, 4 s of rest) on six occasions for 30 min or to task failure, whichever occurred sooner. Four trials were performed above CT (trials S1-S4, S1 being the lowest intensity), and two were performed below CT (at 50% and 90% of CT). Global, central, and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. The complexity of torque output was determined using approximate entropy (ApEn) and the detrended fluctuation analysis-α scaling exponent (DFA-α). The MVC torque was reduced in trials below CT [by 19 ± 4% (means ± SE) in 90%CT], but complexity did not decrease [ApEn for 90%CT: from 0.82 ± 0.03 to 0.75 ± 0.06, 95% paired-samples confidence intervals (CIs), 95% CI = -0.23, 0.10; DFA-α from 1.36 ± 0.01 to 1.32 ± 0.03, 95% CI -0.12, 0.04]. Above CT, substantial reductions in MVC torque occurred (of 49 ± 8% in S1), and torque complexity was reduced (ApEn for S1: from 0.67 ± 0.06 to 0.14 ± 0.01, 95% CI = -0.72, -0.33; DFA-α from 1.38 ± 0.03 to 1.58 ± 0.01, 95% CI 0.12, 0.29). Thus, in these experiments, the fatigue-induced loss of torque complexity occurred exclusively during contractions performed above the CT. Copyright © 2016 the American Physiological Society.

  6. Underground verification of the large deflection performance of fibre reinforced shotcrete subjected to high stresses and convergence and to dynamic loading.

    CSIR Research Space (South Africa)

    Joughin, WC

    2002-04-01

    Full Text Available Committee Final Project Report Underground verification of the large deflection performance of fibre reinforced shotcrete subjected to high stresses and convergence and to dynamic loading W.C. Joughin, J.L. Human and P.J. Terbrugge Research agency...: Steffen, Robertson and Kirsten Project number: GAP 710 Date: April 2002 2 Executive summary The underground verification of the performance of fibre reinforced shotcrete, subject to high stresses, convergence and dynamic loading, was identified...

  7. Capability and recruitment patterns of trunk during isometric uniaxial and biaxial upright exertion.

    Science.gov (United States)

    Sheikhzadeh, Ali; Parnianpour, Mohamad; Nordin, Margareta

    2008-06-01

    Work-related risk factors of low back disorders have been identified to be external moments, awkward postures, and asymmetrical dynamic lifting amongst others. The distinct role of asymmetry of load versus posture is hard to discern from the literature. Hence, the aim of this study is to measure isometric trunk exertions at upright standing posture at different exertion level and degree of asymmetry to further delineate the effects of exertion level and asymmetry on neuromuscular capability response. Fifteen healthy volunteers randomly performed trunk exertions at three levels (30%, 60%, and 100% of maximum voluntary exertion and five different angles (0 degrees , 45 degrees , 90 degrees , 135 degrees , and 180 degrees ) of normalized resultant moments. During each trial, the normalized EMG activity of 10 selected trunk muscles was quantified. The EMG activity of the 10 trunk muscles was significantly (Presultant moment, and their interactions. The controllability of the torque generation was reduced in biaxial exertions. The capability to generate and control the required trunk moments is significantly lowered during biaxial trunk exertions, while all muscles present higher EMG activity. These results suggest that the trunk muscles will be taxed higher while performing biaxial exertion tasks, increasing muscle fatigue possibly leading to a higher probability of low back injury. The prediction of biaxial trunk performance based on uniaxial data will result in an overestimation of capability and controllability of the trunk during physically demanding tasks. This study provides a better understanding of the potential mechanisms of injury during asymmetrical and biaxial trunk exertion during work-related tasks.

  8. Tribological performance evaluation of coated steels with TiNbCN subjected to tribo-chemical wear in Ringers solution

    Energy Technology Data Exchange (ETDEWEB)

    Caballero G, J.; Aperador, W. [Universidad Militar Nueva Granada, Volta Research Group, 101-80 Bogota (Colombia); Caicedo, J. C., E-mail: g.ing.materiales@gmail.com [Universidad del Valle, Tribology Polymers, Powder Metallurgy and Processing of Solid Recycled Research Group, Cali (Colombia)

    2016-11-01

    With the aim of generating solutions against the deterioration of the joint prostheses, it was studied the tribo-corrosive behavior of titanium niobium carbonitride (TiNbCN) deposited on stainless steel AISI 316 LVM using the technique of magnetron sputtering physical vapor deposition. The tests were performed in a balanced saline solution (Ringers solution) which represents the characteristics of the body fluids, using an equipment where the micro-abrasive wear is generated by the contact of micro particles in the system; the micro-abrasion-corrosion mechanism is described by means of the incorporation of an electrochemical cell consisting of three electrodes. Both the substrate and the coating, were subjected to micro-abrasive wear simultaneously with the electrochemical tests of Tafel polarization curves and electrochemical impedance spectroscopy (EIS); subsequently of the tests, the specimens were analyzed by optical microscopy and scanning electron microscopy characterizing the surface morphology. It was observed that the coating presents an increase in its corrosion and wear resistance with the presence of a simulated biological fluid. The samples were characterized via X-ray diffraction. (Author)

  9. Performance of Patient-Generated Subjective Global Assessment (PG-SGA) in Patients With Advanced Cancer in Palliative Care.

    Science.gov (United States)

    Wiegert, Emanuelly Varea Maria; Padilha, Patricia de Carvalho; Peres, Wilza Arantes Ferreira

    2017-10-01

    The purpose of this study was to evaluate the prognostic significance of the Patient-Generated Subjective Global Assessment (PG-SGA) in patients receiving palliative care for advanced cancer. The PG-SGA was used to assess nutrition status of 120 patients admitted to the Palliative Care Unit at the National Cancer Institute in Brazil. According to the PG-SGA, 94.2% (n = 113) of the patients were evaluated as malnourished. The PG-SGA evaluated that xerostomia was the only symptom associated with a short survival (odds ratio [OR], 2.54; 95% confidence interval [CI], 1.2-5.38; P = .014). Survival was found to be significantly higher in well-nourished (PG-SGA A) than malnourished (PG-SGA B [ P = .021] or C [ P = .013]) patients. Total PG-SGA score (hazard ratio [HR], 1.06; 95% CI, 1.001-1.09; P = .045) and Karnofsky Performance Status of 20%-30% (HR, 15.4; 95% CI, 1.63-92.9; P = .001) and 40%-50% (HR, 10.0; 95% CI, 1.22-64.9; P = .031) were found to be independent prognostic survival factors. The scored PG-SGA is an independent prognostic factor of survival and thus can be a useful tool for nutrition evaluation in palliative care.

  10. [Comparison of the effectiveness of isokinetic vs isometric therapeutic exercise in patients with osteoarthritis of knee].

    Science.gov (United States)

    Rosa, Uganet Hernández; Velásquez Tlapanco, Jorge; Lara Maya, Catalina; Villarreal Ríos, Enrique; Martínez González, Lidia; Vargas Daza, Emma Rosa; Galicia Rodríguez, Liliana

    2012-01-01

    Osteoarthritis is a chronic joint disease; isometric exercise leads to the development of mechanical work and isokinetic exercise leads to better joint mobility. To compare the effectiveness of isometric versus isokinetic therapeutic exercises in patients with knee osteoarthritis. Quasiexperimental study in a population of 45 to 75 year old patients with a diagnosis of knee osteoarthritis. Group 1 (experimental) was put under isokinetic exercises and group 2 (control) under isometric exercises. The sample size was of 33 patients per group; the allocation to the experimentation or control group was nonrandom, but stratified by degrees of knee osteoarthritis. The effectiveness of the exercise was measured in three dimensions: muscle strength, joint range and pain. The intervention lasted eight weeks and the physical activity was carried out every third day. The statistical analysis included averages, standard deviation, percentage, Chi square test, z test for two populations, t test for two independent populations and twin t test. The analysis of muscle strength comparing the categories independently demonstrates differences at 8 weeks; 33.3% of the isokinetic exercise is in the normal category and 15.2% in the isometric exercise (p= 0.04). There was not difference of joint range between groups, despite finding a stage I range in 100.0% of the isokinetic group and 97.0% in the isometric (p> 0.05) group. Pain was milder in the isokinetic exercise group at 8 weeks (p= 0.01) Isokinetic exercises have a greater effectiveness than isometric exercises for muscle strength and pain in patients with knee osteoarthritis. However, other studies with randomized designs are needed. Copyright © 2011 Elsevier España, S.L. All rights reserved.

  11. Cilnidipine but not amlodipine suppresses sympathetic activation elicited by isometric exercise in hypertensive patients.

    Science.gov (United States)

    Koike, Yumi; Kawabe, Tetsuya; Nishihara, Kanami; Iwane, Naomi; Hano, Takuzo

    2015-01-01

    Pupillometry was used to evaluate the effects of the calcium channel blockers cilnidipine (CL) and amlodipine (AM) on changes in autonomic nervous activity induced by isometric exercise in patients with hypertension. After handgrip exercise, the velocity of miosis increased in both the CL and AM groups. However, the velocity of mydriasis increased in only the AM group. Velocity slopes of miosis and mydriasis were smaller in the CL group than in the AM group. The low-to-high frequency ratio obtained from pulse wave analysis increased in only the AM group. Sympathetic activation elicited by isometric exercise was suppressed more effectively by CL than by AM.

  12. Intramuscular pressure, tissue oxygenation, and muscle fatigue of the multifidus during isometric extension in elite rowers with low back pain.

    Science.gov (United States)

    Dehner, Christoph; Schmelz, Andreas; Völker, Hans-Ullrich; Pressmar, Jochen; Elbel, Martin; Kramer, Michael

    2009-11-01

    Chronic low back pain (LBP) has been reported with a high incidence in elite rowers. It results in less effective training, long interruptions in training, and a drop in performance. The authors hypothesized that exercise-induced LBP in rowers is caused by a chronic functional compartment syndrome (CFCS) of the multifidus muscle. Controlled clinical trial. The rowers were tested in their training camp. The control group was tested at a university hospital. 14 volunteer elite rowers complaining of LBP and 16 healthy volunteer amateur athletes. Intramuscular pressure (IMP), tissue oxygenation pressure (pO2), and median frequency (MF) shift in the electromyographic power density spectrum during isometric fatiguing extension at 60% of maximum voluntary contraction. At the beginning (controls 186.6 mm Hg vs rowers 60.2 mm Hg, P = .002) and the end (controls 224.1 mm HG vs rowers 77.1 mm Hg, P pain generation during exercise in elite rowers.

  13. The effects of isometric contraction of shoulder muscles on cervical multifidus muscle dimensions in healthy office workers.

    Science.gov (United States)

    Rahnama, Leila; Rezasoltani, Asghar; Khalkhali Zavieh, Minoo; Noori Kochi, Farhang; Akbarzadeh Baghban, Alireza

    2014-07-01

    It is argued that cervical multifidus muscles (CMM) are responsible for providing neck stability. However, whether they are actually activated during the tasks performed by the upper extremities to the neck is still unknown. Therefore, the aim of this study was to examine the effects of isometric contraction of shoulder muscles on the dimensions of CMM. Twenty three healthy males voluntarily participated in this study. Ultrasonography imaging of CMM was conducted at rest and at 25%, 50%, 75%, and 100% of maximal voluntary contraction of shoulder muscles in 6 directions of shoulder movements. Anterior-posterior dimension (APD), lateral dimension (LD), shape ratio and multiplied linear dimension (MLD) of cervical multifidus were measured. The APD of CMM was increased while LD and shape ratio were decreased by shoulder muscles contraction (P < 0.01). Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Testing of Performance of Optical Fibers Under Irradiation in Intense Radiation Fields, When Subjected to Very High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Thomas [The Ohio State Univ., Columbus, OH (United States); Windl, Wolfgang [The Ohio State Univ., Columbus, OH (United States); Dickerson, Bryan [Luna Innovations, Inc. (United States)

    2013-01-03

    The primary objective of this project is to measure and model the performance of optical fibers in intense radiation fields when subjected to very high temperatures. This research will pave the way for fiber optic and optically based sensors under conditions expected in future high-temperature gas-cooled reactors. Sensor life and signal-to-noise ratios are susceptible to attenuation of the light signal due to scattering and absorbance in the fibers. This project will provide an experimental and theoretical study of the darkening of optical fibers in high-radiation and high-temperature environments. Although optical fibers have been studied for moderate radiation fluence and flux levels, the results of irradiation at very high temperatures have not been published for extended in-core exposures. Several previous multi-scale modeling efforts have studied irradiation effects on the mechanical properties of materials. However, model-based prediction of irradiation-induced changes in silica's optical transport properties has only recently started to receive attention due to possible applications as optical transmission components in fusion reactors. Nearly all damage-modeling studies have been performed in the molecular-dynamics domain, limited to very short times and small systems. Extended-time modeling, however, is crucial to predicting the long-term effects of irradiation at high temperatures, since the experimental testing may not encompass the displacement rate that the fibers will encounter if they are deployed in the VHTR. The project team will pursue such extended-time modeling, including the effects of the ambient and recrystallization. The process will be based on kinetic MC modeling using the concept of amorphous material consisting of building blocks of defect-pairs or clusters, which has been successfully applied to kinetic modeling in amorphized and recrystallized silicon. Using this procedure, the team will model compensation for rate effects, and

  15. Effects of repeated snowboard exercise in virtual reality with time lags of visual scene behind body rotation on head stability and subjective slalom run performance in healthy young subjects.

    Science.gov (United States)

    Wada, Yoshiro; Nishiike, Suetaka; Kitahara, Tadashi; Yamanaka, Toshiaki; Imai, Takao; Ito, Taeko; Sato, Go; Matsuda, Kazunori; Kitamura, Yoshiaki; Takeda, Noriaki

    2016-11-01

    After repeated snowboard exercises in the virtual reality (VR) world with increasing time lags in trials 3-8, it is suggested that the adaptation to repeated visual-vestibulosomatosensory conflict in the VR world improved dynamic posture control and motor performance in the real world without the development of motion sickness. The VR technology was used and the effects of repeated snowboard exercise examined in the VR world with time lags between visual scene and body rotation on the head stability and slalom run performance during exercise in healthy subjects. Forty-two healthy young subjects participated in the study. After trials 1 and 2 of snowboard exercise in the VR world without time lag, trials 3-8 were conducted with 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 s time lags of the visual scene that the computer creates behind board rotation, respectively. Finally, trial 9 was conducted without time lag. Head linear accelerations and subjective slalom run performance were evaluated. The standard deviations of head linear accelerations in inter-aural direction were significantly increased in trial 8, with a time lag of 0.6 s, but significantly decreased in trial 9 without a time lag, compared with those in trial 2 without a time lag. The subjective scores of slalom run performance were significantly decreased in trial 8, with a time lag of 0.6 s, but significantly increased in trial 9 without a time lag, compared with those in trial 2 without a time lag. Motion sickness was not induced in any subjects.

  16. Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

    National Research Council Canada - National Science Library

    Jaeyoung Song; Kyuhwan Oh; Byoungil Kim; Sangkeun Oh

    2017-01-01

    .... In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult...

  17. Reduced modulation of pain in older adults following isometric and aerobic exercise

    Science.gov (United States)

    Naugle, Kelly M.; Naugle, Keith E.; Riley, Joseph L.

    2016-01-01

    Laboratory based studies show that acute aerobic and isometric exercise reduces sensitivity to painful stimuli in young healthy individuals, indicative of a hypoalgesic response. However, little is known regarding the effect of aging on exercise-induced hypoalgesia (EIH). The purpose of this study was to examine age differences in EIH following submaximal isometric exercise, and moderate and vigorous aerobic exercise. Healthy older and younger adults completed one training session and four testing sessions consisting of either a submaximal isometric handgrip exercise, vigorous or moderate intensity stationary cycling, or quiet rest (control). The following measures were taken pre and post exercise/quiet rest: 1) pressure pain thresholds (PPTs), 2) suprathreshold pressure pain ratings, 3) pain ratings during 30-s of prolonged noxious heat stimulation, and 3) temporal summation of heat pain. The results revealed age differences in EIH following isometric and aerobic exercise, with younger adults experiencing greater EIH compared to older adults. The age differences in EIH varied across pain induction techniques and exercise type. These results provide evidence for abnormal pain modulation following acute exercise in older adults. PERSPECTIVE This article enhances our understanding of the influence of a single bout of exercise on pain sensitivity and perception in healthy older compared to younger adults. This knowledge could potentially help clinicians optimize exercise as a method of pain management. PMID:26993959

  18. Reduced Modulation of Pain in Older Adults After Isometric and Aerobic Exercise.

    Science.gov (United States)

    Naugle, Kelly M; Naugle, Keith E; Riley, Joseph L

    2016-06-01

    Laboratory-based studies show that acute aerobic and isometric exercise reduces sensitivity to painful stimuli in young healthy individuals, indicative of a hypoalgesic response. However, little is known regarding the effect of aging on exercise-induced hypoalgesia (EIH). The purpose of this study was to examine age differences in EIH after submaximal isometric exercise and moderate and vigorous aerobic exercise. Healthy older and younger adults completed 1 training session and 4 testing sessions consisting of a submaximal isometric handgrip exercise, vigorous or moderate intensity stationary cycling, or quiet rest (control). The following measures were taken before and after exercise/quiet rest: 1) pressure pain thresholds, 2) suprathreshold pressure pain ratings, 3) pain ratings during 30 seconds of prolonged noxious heat stimulation, and 4) temporal summation of heat pain. The results revealed age differences in EIH after isometric and aerobic exercise, with younger adults experiencing greater EIH compared with older adults. The age differences in EIH varied across pain induction techniques and exercise type. These results provide evidence for abnormal pain modulation after acute exercise in older adults. This article enhances our understanding of the influence of a single bout of exercise on pain sensitivity and perception in healthy older compared with younger adults. This knowledge could help clinicians optimize exercise as a method of pain management. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

  19. Effect of trunk inclination on isometric extensor and flexor torque of ...

    African Journals Online (AJOL)

    A Cybex 6000, dynamometer Trunk extension / flexion unit was used to measure maximal voluntary isometric strength of the lumbar flexor and extensor muscles at 0, 23, 46, 69 and 92 degrees of trunk flexion. ANOVA with post-hoc testing was applied to the flexion and extension data. Alpha was set at p < 0.05. Significant ...

  20. The Relationship Between Maximum Isometric Strength and Ball Velocity in the Tennis Serve

    Directory of Open Access Journals (Sweden)

    Baiget Ernest

    2016-12-01

    Full Text Available The aims of this study were to analyze the relationship between maximum isometric strength levels in different upper and lower limb joints and serve velocity in competitive tennis players as well as to develop a prediction model based on this information. Twelve male competitive tennis players (mean ± SD; age: 17.2 ± 1.0 years; body height: 180.1 ± 6.2 cm; body mass: 71.9 ± 5.6 kg were tested using maximum isometric strength levels (i.e., wrist, elbow and shoulder flexion and extension; leg and back extension; shoulder external and internal rotation. Serve velocity was measured using a radar gun. Results showed a strong positive relationship between serve velocity and shoulder internal rotation (r = 0.67; p < 0.05. Low to moderate correlations were also found between serve velocity and wrist, elbow and shoulder flexion – extension, leg and back extension and shoulder external rotation (r = 0.36 – 0.53; p = 0.377 – 0.054. Bivariate and multivariate models for predicting serve velocity were developed, with shoulder flexion and internal rotation explaining 55% of the variance in serve velocity (r = 0.74; p < 0.001. The maximum isometric strength level in shoulder internal rotation was strongly related to serve velocity, and a large part of the variability in serve velocity was explained by the maximum isometric strength levels in shoulder internal rotation and shoulder flexion.

  1. The effects of imagery training on fast isometric knee extensor torque development

    NARCIS (Netherlands)

    de Ruiter, Cornelis J.; Hutter, Vana; Icke, Chris; Groen, Bart; Gemmink, Anne; Smilde, Hiltsje; de Haan, Arnold

    2012-01-01

    We hypothesized that imagery training would improve the fast onset of neuromuscular activation and thereby fast knee extensor isometric torque development. Forty young healthy participants, not involved in strength training, were assigned to one of four groups: physical training, imagery training,

  2. Effects of age and content of augmented feedback on learning an isometric force-production task

    NARCIS (Netherlands)

    van Dijk, Henk; Mulder, Theo; Hermens, Hermie J.

    2007-01-01

    This study addressed the interaction between age and the informational content of feedback on learning an isometric force-production task. Healthy men and women (30 young adults: 20 to 35 years; 30 older adults: 55 to 70 years) were randomly assigned to a certain type of feedback: knowledge of

  3. Isometric muscle strength and mobility capacity in children with cerebral palsy

    NARCIS (Netherlands)

    Dallmeijer, Annet J.; Rameckers, Eugene A.; Houdijk, Han; de Groot, Sonja; Scholtes, Vanessa A.; Becher, Jules G.

    2017-01-01

    Purpose: To determine the relationship between isometric leg muscle strength and mobility capacity in children with cerebral palsy (CP) compared to typically developing (TD) peers. Method: Participants were 62 children with CP (6-13 years), able to walk with (n=10) or without (n=52) walking aids,

  4. Isometric behavior of the reconstructed medial patellofemoral ligament using two different femoral pulleys: a cadaveric study.

    Science.gov (United States)

    Triantafillopoulos, Ioannis K; Panagopoulos, Andreas; van Niekerk, Louw

    2007-09-01

    Several techniques have been described for reconstructing the medial patellofemoral ligament (MPFL). However, the anatomy of the medial patellar retinaculum and the isometry of both intact and reconstructed MPFL remain controversial. The purpose of this study was to investigate the isometric behavior of the reconstructed MPFL when two different pulleys are used for the reconstruction. Eight anatomical knees were dissected and the medial patellar retinaculum and MPFL were studied. A pilot technique for the reconstruction of the MPFL using a semitendinosus autograft was developed. A "dynamic" femoral fixation was chosen which utilized two different pulleys: the medial intermuscular septum (MIS) at the adductor's tendon insertion and the posterior third of the medial collateral ligament (MCL). The isometric behavior of the reconstructed MPFL and the stability of both pulleys were investigated. The MPFL was a thickened, band-like condensation of the superficial MPR layer extending from the MFE to the medial border of the patella. The reconstructed MPFL demonstrated the most isometric behavior when the MCL was used as a pulley. The average difference in graft length during knee flexion from 0 degrees to 90 degrees when the MCL or MIS were used as a pulley was 1 mm and 4 mm, respectively. The MIS pulley was more stable but less isometric than the MCL pulley. "Dynamic" MPFL reconstruction with a semitendinosus tendon autograft can restore patellofemoral stability without excessive soft-tissue dissection or implantation of hardware at the medial epicondyle, which can lead to symptoms of its own.

  5. Effects of age and content of augmented feedback on learning an isometric force-production task

    NARCIS (Netherlands)

    van Dijk, H; Mulder, T.; Hermens, Hermanus J.

    This study addressed the interaction between age and the informational content of feedback on learning an isometric force-production task. Healthy men and women (30 young adults: 20 to 35 years; 30 older adults: 55 to 70 years) were randomly assigned to a certain type of feedback: knowledge of

  6. Comparative study on anterior cruciate ligament reconstruction: determination of isometric points with and without navigation

    Directory of Open Access Journals (Sweden)

    Fabio J. Angelini

    2010-01-01

    Full Text Available OBJECTIVES: To compare the accuracy of tunnel placement and graft isometry for anterior cruciate ligament reconstruction performed using a computer-assisted navigation system (Orthopilot and using traditional instruments. METHODS: The anterior cruciate ligament was removed intact from 36 pairs of human cadaver knees. From each pair, one knee was randomized to Group 1 (conventional and the other to Group 2 (Orthopilot. An inelastic suture was then passed through the central points of the tibial and femoral tunnels. Neither of the tunnels was drilled. All knees were then dissected, and six parameters were obtained: distances from the tibial tunnel center to the 1 posterior cruciate ligament, 2 anterior horn of the lateral meniscus and 3 medial tibial spine; 4 distance from the femoral tunnel center to the posterior femoral cortex; 5 femoral tunnel coronal angle; and 6 variation of the distance from the femoral to the tibial tunnel with the knee extended and at 90 degrees of flexion. RESULTS: The variation of the distance from the femoral to the tibial tunnel during flexion and extension was smaller in the Orthopilot group (better isometry compared to the conventional group. There were no statistical differences in any other parameters between the groups, and all tunnels were considered to be in satisfactory positions. DISCUSSION: The results obtained for anterior cruciate ligament reconstruction depend on precise isometric point positioning, and a navigation system is a precision tool that can assist surgeons in tunnel positioning. CONCLUSION: No differences in tunnel position were observed between the groups. Nonetheless, better isometry was achieved in the Orthopilot group than with conventional instruments.

  7. Isometric muscle strength and mobility capacity in children with cerebral palsy.

    Science.gov (United States)

    Dallmeijer, Annet J; Rameckers, Eugene A; Houdijk, Han; de Groot, Sonja; Scholtes, Vanessa A; Becher, Jules G

    2017-01-01

    To determine the relationship between isometric leg muscle strength and mobility capacity in children with cerebral palsy (CP) compared to typically developing (TD) peers. Participants were 62 children with CP (6-13 years), able to walk with (n = 10) or without (n = 52) walking aids, and 47 TD children. Isometric muscle strength of five muscle groups of the leg was measured using hand-held dynamometry. Mobility capacity was assessed with the 1-min walk, the 10-m walk, sit-to-stand, lateral-step-up and timed-stair tests. Isometric strength of children with CP was reduced to 36-82% of TD. When adjusted for age and height, the percentage of variance in mobility capacity that was explained by isometric strength of the leg muscles was 21-24% (walking speed), 25% (sit-to-stand), 28% (lateral-step-up) and 35% (timed-stair) in children with CP. Hip abductors and knee flexors had the largest contribution to the explained variance, while knee extensors showed the weakest correlation. Weak or no associations were found between strength and mobility capacity in TD children. Isometric strength, especially hip abductor and knee flexor strength, is moderately related to mobility capacity in children with CP, but not in TD children. To what extent training of these muscle groups will lead to better mobility capacity needs further study. Implications for Rehabilitation Strength training in children with cerebral palsy (CP) may be targeted more specifically at hip abductors and knee flexors. The moderate associations imply that large improvements in mobility capacity may not be expected when strength increases.

  8. Retraining and assessing hand movement after stroke using the MusicGlove: comparison with conventional hand therapy and isometric grip training.

    Science.gov (United States)

    Friedman, Nizan; Chan, Vicky; Reinkensmeyer, Andrea N; Beroukhim, Ariel; Zambrano, Gregory J; Bachman, Mark; Reinkensmeyer, David J

    2014-04-30

    It is thought that therapy should be functional, be highly repetitive, and promote afferent input to best stimulate hand motor recovery after stroke, yet patients struggle to access such therapy. We developed the MusicGlove, an instrumented glove that requires the user to practice gripping-like movements and thumb-finger opposition to play a highly engaging, music-based, video game. The purpose of this study was to 1) compare the effect of training with MusicGlove to conventional hand therapy 2) determine if MusicGlove training was more effective than a matched form of isometric hand movement training; and 3) determine if MusicGlove game scores predict clinical outcomes. 12 chronic stroke survivors with moderate hemiparesis were randomly assigned to receive MusicGlove, isometric, and conventional hand therapy in a within-subjects design. Each subject participated in six one-hour treatment sessions three times per week for two weeks, for each training type, for a total of 18 treatment sessions. A blinded rater assessed hand impairment before and after each training type and at one-month follow-up including the Box and Blocks (B & B) test as the primary outcome measure. Subjects also completed the Intrinsic Motivation Inventory (IMI). Subjects improved hand function related to grasping small objects more after MusicGlove compared to conventional training, as measured by the B & B score (improvement of 3.21±3.82 vs. -0.29±2.27 blocks; P=0.010) and the 9 Hole Peg test (improvement of 2.14±2.98 vs. -0.85±1.29 pegs/minute; P=0.005). There was no significant difference between training types in the broader assessment batteries of hand function. Subjects benefited less from isometric therapy than MusicGlove training, but the difference was not significant (P>0.09). Subjects sustained improvements in hand function at a one month follow-up, and found the MusicGlove more motivating than the other two therapies, as measured by the IMI. MusicGlove games scores correlated

  9. Age Differences in Noise and Variability of Isometric Force Production.

    Science.gov (United States)

    Deutsch, Katherine M.; Newell, Karl M.

    2001-01-01

    Examined whether age-related improvements in children's motor performance result from reduced noise in the output of the sensorimotor system. Found that performance improved with age. The force output signal exhibited increased irregularity and a more broadband frequency profile with increasing age under feedback. There were no age differences in…

  10. Isometric rate of force development, maximum voluntary contraction, and balance in women with and without joint hypermobility.

    Science.gov (United States)

    Mebes, Christine; Amstutz, Astrid; Luder, Gere; Ziswiler, Hans-Ruedi; Stettler, Matthias; Villiger, Peter M; Radlinger, Lorenz

    2008-11-15

    To determine differences between hypermobile subjects and controls in terms of maximum strength, rate of force development, and balance. We recruited 13 subjects with hypermobility and 18 controls. Rate of force development and maximal voluntary contraction (MVC) during single leg knee extension of the right knee were measured isometrically for each subject. Balance was tested twice on a force plate with 15-second single-leg stands on the right leg. Rate of force development (N/second) and MVC (N) were extracted from the force-time curve as maximal rate of force development (= limit Deltaforce/Deltatime) and the absolute maximal value, respectively. The hypermobile subjects showed a significantly higher value for rate of force development (15.2% higher; P = 0.038, P = 0.453, epsilon = 0.693) and rate of force development related to body weight (16.4% higher; P = 0.018, P = 0.601, epsilon = 0.834) than the controls. The groups did not differ significantly in MVC (P = 0.767, P = 0.136, epsilon = 0.065), and MVC related to body weight varied randomly between the groups (P = 0.921, P = 0.050, epsilon = 0.000). In balance testing, the mediolateral sway of the hypermobile subjects showed significantly higher values (11.6% higher; P = 0.034, P = 0.050, epsilon = 0.000) than that of controls, but there was no significant difference (4.9% difference; P = 0.953, P = 0.050, epsilon = 0.000) in anteroposterior sway between the 2 groups. Hypermobile women without acute symptoms or limitations in activities of daily life have a higher rate of force development in the knee extensors and a higher mediolateral sway than controls with normal joint mobility.

  11. Oral structure nonspeech motor control in normal, dysarthric, aphasic and apraxic speakers: isometric force and static position control.

    Science.gov (United States)

    McNeil, M R; Weismer, G; Adams, S; Mulligan, M

    1990-06-01

    This study investigated the isometric force and static position control of the upper lip, lower lip, tongue, jaw, and finger in four subject groups (normal control, apraxia of speech, conduction aphasia, and ataxic dysarthria) at two force and displacement levels. Results from both the force and position tasks suggested that the apraxic and dysarthric groups tended to produce significantly greater instability than the normal group, although the pattern of instability across articulators was not systematic within or across the force and position experiments for subjects within or between groups. The conduction aphasic group produced force and position stability that typically was not significantly different from any of the remaining three groups, suggesting that their force and position stability as indexed in the present study fell somewhere between that of the normal group and the apraxic and dysarthric groups. It is suggested that other analyses of force and position control, such as descriptive accounts of the trial-by-trial time histories, might shed additional light on the speech and orofacial sensorimotor control deficits in persons with apraxia, dysarthria, and conduction aphasia.

  12. COMPARISON BETWEEN POST ISOMETRIC RELAXATION AND RECIPROCAL INHIBITION MANUEVERS ON HAMSTRING FLEXIBILITY IN YOUNG HEALTHY ADULTS: RANDOMIZED CLINICAL TRIAL

    Directory of Open Access Journals (Sweden)

    Agrawal Sonal S

    2016-01-01

    Full Text Available Background & Purpose: Variations in the application of muscle energy technique (MET for increasing the extensibility of muscles have been advocated, but little evidence exists to support the relative merit of a particular approach. This study investigated two types of muscle energy techniques that have been advocated in the osteopathic literature that differ primarily in the muscle group targeted. Aim: To compare the efficacy of Post Isometric Relaxation (PIR and Reciprocal Inhibition (RI on hamstring length in young healthy adults Methodology: Randomized clinical trial 100 college students aged between 18-25 years were included. The subjects were randomly assigned to PIR and RI group. Each group consisted of 50 subjects (25 male, 25 female. Knee extension limitation was measured by using active knee extension test (AKET pre & post-intervention, i.e. after 3 weeks of stretching regimen, with the help of universal full circle goniometer. Results: There was significant improvement in hamstrings flexibility (p=0.000 in both PIR and RI groups. Statistical comparison of the results of both the technique showed that PIR group had greater improvement than the RI group (p=0.000 Conclusion: PIR and RI were both found to be effective in improving hamstring flexibility but, PIR is more effective therapeutic maneuver.

  13. Measuring Cognitive Load during Simulation-Based Psychomotor Skills Training: Sensitivity of Secondary-Task Performance and Subjective Ratings

    Science.gov (United States)

    Haji, Faizal A.; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

    2015-01-01

    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance…

  14. Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

    OpenAIRE

    Jaeyoung Song; Kyuhwan Oh; Byoungil Kim; Sangkeun Oh

    2017-01-01

    Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from...

  15. Silicon Carbide (SiC) Device and Module Reliability, Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field

    Science.gov (United States)

    2016-05-01

    magnitude and direction, which are generated from a transitory and spatial acceleration vector field and their impact on the dynamical performance of two...Heat Input to an Acceleration Field Kirk L. Yerkes (AFRL/RQQI) and James D. Scofield (AFRL/RQQE) Flight Systems Integration Branch (AFRL/RQQI...CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field 5a

  16. Being a SportParent: Buffering the effect of your talented child's poor performance on his or her subjective well-being

    NARCIS (Netherlands)

    Van Yperen, N.W.

    1998-01-01

    The focus of this longitudinal study was the process that can explain why poor performance (as assessed by the coach) may lead to less subjective well-being. The participants were 59 young, highly skilled male soccer players (mean age: 15.6 years) attending a prestigious soccer school. In line with

  17. Perceptions, Attitudes and Institutional Factors That Influence Academic Performance of Visual Arts Students in Ghana's Senior High School Core Curriculum Subjects

    Science.gov (United States)

    Opoku-Asare, Nana Afia; Tachie-Menson, Akosua; Essel, Harry Barton

    2015-01-01

    Senior High School (SHS) students in Ghana are required to pass all core and elective curricula subjects in the West Africa Senior School Certificate Examination (WASSCE) to qualify for higher education. Unfortunately, many Visual Arts students perform poorly or fail in English, Mathematics, Integrated Science and Social Studies, which constitute…

  18. Attitudes, subjective norms, and intention to perform routine oral examination for oropharyngeal candidiasis as perceived by primary health-care providers in Nairobi Province

    NARCIS (Netherlands)

    Koyio, L.N.; Kikwilu, E.N.; Mulder, J.; Frencken, J.E.F.M.

    2013-01-01

    Objectives: To assess attitudes, subjective norms, and intentions of primary health-care (PHC) providers in performing routine oral examination for oropharyngeal candidiasis (OPC) during outpatient consultations. Methods: A 47-item Theory of Planned Behaviour-based questionnaire was developed and

  19. Examining the Effects of Perceived Relevance and Work-Related Subjective Well-Being on Individual Performance for Co-Op Students

    Science.gov (United States)

    Drewery, Dave; Pretti, T. Judene; Barclay, Sage

    2016-01-01

    The purpose of this study was to examine the relationships between co-op students' perceived relevance of their work term, work-related subjective well-being (SWB), and individual performance at work. Data were collected using a survey of co-op students (n = 1,989) upon completion of a work term. Results of regression analyses testing a…

  20. Reliability of the Q Force; a mobile instrument for measuring isometric quadriceps muscle strength.

    Science.gov (United States)

    Douma, K W; Regterschot, G R H; Krijnen, W P; Slager, G E C; van der Schans, C P; Zijlstra, W

    2016-01-01

    The ability to generate muscle strength is a pre-requisite for all human movement. Decreased quadriceps muscle strength is frequently observed in older adults and is associated with a decreased performance and activity limitations. To quantify the quadriceps muscle strength and to monitor changes over time, instruments and procedures with a sufficient reliability are needed. The Q Force is an innovative mobile muscle strength measurement instrument suitable to measure in various degrees of extension. Measurements between 110 and 130° extension present the highest values and the most significant increase after training. The objective of this study is to determine the test-retest reliability of muscle strength measurements by the Q Force in older adults in 110° extension. Forty-one healthy older adults, 13 males and 28 females were included in the study. Mean (SD) age was 81.9 (4.89) years. Isometric muscle strength of the Quadriceps muscle was assessed with the Q Force at 110° of knee extension. Participants were measured at two sessions with a three to eight day interval between sessions. To determine relative reliability, the intraclass correlation coefficient (ICC) was calculated. To determine absolute reliability, Bland and Altman Limits of Agreement (LOA) were calculated and t-tests were performed. Relative reliability of the Q Force is good to excellent as all ICC coefficients are higher than 0.75. Generally a large 95 % LOA, reflecting only moderate absolute reliability, is found as exemplified for the peak torque left leg of -18.6 N to 33.8 N and the right leg of -9.2 N to 26.4 N was between 15.7 and 23.6 Newton representing 25.2 % to 39.9 % of the size of the mean. Small systematic differences in mean were found between measurement session 1 and 2. The present study shows that the Q Force has excellent relative test-retest reliability, but limited absolute test-retest reliability. Since the Q Force is relatively cheap and mobile it is suitable for

  1. Novel Use of the Nintendo Wii Board for Measuring Isometric Lower Limb Strength

    DEFF Research Database (Denmark)

    Gronbech Jorgensen, Martin; Andersen, Stig; Ryg, Jesper

    BACKGROUND: Portable, low-cost, objective and reproducible assessment of muscle strength in the lower limbs is important as it allows clinicians to precisly track progression of patients undergoing rehabilitation. The Nintendo Wii Balance Board (WBB) is portable, inexpensive, durable, available...... worldwide, and may serve the above function. OBJECTIVE: The purpose of the study was to evaluate (1) reproducibility and (2) concurrent validity of the WBB for measuring isometric muscle strength in the lower limb. METHODS: A custom hardware and software was developed to utilize the WBB for assessment...... the difference and the mean. CONCLUSIONS: A high relative and an acceptable absolute reproducibility combined with a good validity was found for the novel method using the WBB for measuring isometric lower limb strength in older adults. Further research using the WBB for assessing lower limb strength should...

  2. Cognitive performance and perceived effort in speech processing tasks: effects of different noise backgrounds in normal-hearing and hearing-impaired subjects.

    Science.gov (United States)

    Larsby, Birgitta; Hällgren, Mathias; Lyxell, Björn; Arlinger, Stig

    2005-03-01

    Cognitive tests of speech understanding were administered (presented as text, or in auditory or audiovisual modality) and perceived effort was rated. This was done in four background conditions: in silence, and in three types of noise (S/N=+10 dB) varying in temporal structure and meaningfulness. Four groups of 12 subjects each (young/elderly with normal hearing and young/elderly with hearing impairment) participated. The presence of noise had a negative effect on accuracy and speed of performance in the speech processing tasks, and resulted in higher scores of perceived effort, even when the stimuli were presented as text. Differences in performance between noise conditions existed. In the subjective scores, the noise with temporal variations, but without meaningful content, was the most disruptive of the three noise conditions. In the objective scores the hearing-impaired subjects showed poorer results in noise with temporal variations. The elderly subjects were more distracted by noise with temporal variations, and especially by noise with meaningful content. In noise, all subjects, particularly those with impaired hearing, were more dependent upon visual cues than in the quiet condition.

  3. The effects of aquatic, isometric strength-stretching and aerobic exercise on physical and psychological parameters of female patients with fibromyalgia syndrome.

    Science.gov (United States)

    Sevimli, Dilek; Kozanoglu, Erkan; Guzel, Rengin; Doganay, Ahmet

    2015-06-01

    [Purpose] There are various treatment modalities for fibromyalgia syndrome (FMS), which is characterized by widespread pain and fatigue. The aim of this study was to investigate the effects of aquatic, aerobic and isometric strength-stretching exercises on the physical and psychological parameters of patients with FMS. [Subjects and Methods] Seventy five female patients with FMS were randomly selected and divided into three groups. Patients (18-50 years) were treated for 3 months using one of three methods: a home-based isometric strength and stretching exercise program (ISSEP), a gym-based aerobic exercise program (AEP), and a pool-based aquatic aerobic exercise program (AAEP). Items evaluated were: the number of tender points, Visual Analog Scale (VAS), Fibromyalgia Impact Questionnaire (FIQ), the Six-Minute Walk Test (6MWT), SF-36 physical and mental health scores, and the Beck Depression Inventory (BDI). [Results] The results revealed that AAEP was the most effective treatment of the three. All of the groups showed significant improvements in all variables between pre-and post-test, except the mean values of VAS and BDI in ISSEP. [Conclusion] The results suggest that aquatic aerobic exercise program is more effective than AEP and ISSEP in the treatment of FMS.

  4. The COFU3 Study. Improvement in cognitive function, attention, mental performance with Pycnogenol® in healthy subjects (55-70) with high oxidative stress.

    Science.gov (United States)

    Belcaro, G; Dugall, M; Ippolito, E; Hu, S; Saggino, A; Feragalli, B

    2015-12-01

    This 12-month product registry study evaluated the effects of supplementation with French pine bark extract (Pycnogenol(®)) on cognitive function, attention, and mental performance in healthy subjects with high oxidative stress. Healthy subjects (age range 55-70) were screened - within a cardiovascular screening program - for oxidative stress. Out of 150 subjects, high oxidative stress was present in 44; the use of the supplement Pycnogenol(®) was suggested (100 mg/day). These subjects decided to use Pycnogenol(®) and accepted to be evaluated by assessing cognitive functions. A group of subjects with comparable oxidative stress was followed as a reference. IQ Code (Informant Questionnaire on Cognitive Decline in the Elderly), daily tasks, cognitive function, oxidative stress and the short Blessed tests (SBT) were used (in defined scales) to evaluate cognitive functions (COFU). As for the IQ Code, at 12 months there was a significantlty total lower score in Pycnogenol(®) patients and also a lower value (PPycnogenol(®) (-28.07%; PPycnogenol(®) group (PPycnogenol(®) were optimal with >97% of the doses of the supplement correctly used. No side effects were observed, recorded or described. Pycnogenol(®) supplementation for 12 months appears to improve cognitive function and oxidative stress in normal subjects between 55 and 70 years of age.

  5. Image Based Calculation of Perfusion and Oxyhemoglobin Saturation in Skeletal Muscle during Submaximal Isometric Contractions

    OpenAIRE

    Elder, Christopher P.; Cook, Ryan N.; Chance, Marti A.; Copenhaver, Elizabeth A.; Damon, Bruce M.

    2010-01-01

    The relative oxygen saturation of hemoglobin (%HbO2) and the rate of perfusion (θ̇) are important physiological quantities, particularly in organs such as skeletal muscle in which oxygen delivery and use are tightly coupled. The purpose of this study was to demonstrate the image-based calculation of %HbO2 and quantification of perfusion in skeletal muscle during isometric contractions. This was accomplished by establishing an empirical relationship between the rate of RF-reversible dephasing ...

  6. ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) INCREASES ISOMETRIC STRENGTH OF SHOULDER ROTATORS MUSCLES IN HANDBALL PLAYERS.

    Science.gov (United States)

    Hazime, Fuad Ahmad; da Cunha, Ronaldo Alves; Soliaman, Renato Rozenblit; Romancini, Ana Clara Bezerra; Pochini, Alberto de Castro; Ejnisman, Benno; Baptista, Abrahão Fontes

    2017-06-01

    Weakness of the rotator cuff muscles can lead to imbalances in the strength of shoulder external and internal rotators, change the biomechanics of the glenohumeral joint and predispose an athlete to injury. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has demonstrated promising results in a variety of health conditions. However few studies addressed its potential approach in the realm of athletics. The purpose of this study was to investigate if transcranial direct current stimulation (tDCS) technique increases the isometric muscle strength of shoulder external and internal rotators in handball athletes. Randomized, double-blind, placebo-controlled, crossover study. Eight female handball players aged between 17 and 21 years (Mean=19.65; SD=2.55) with 7.1 ± 4.8 years of experience in training, participating in regional and national competitions were recruited. Maximal voluntary isometric contraction (MVIC) of shoulder external and internal rotator muscles was evaluated during and after 30 and 60 minutes post one session of anodal and sham current (2mA; 0.057mA/cm2) with a one-week interval between stimulations. Compared to baseline, MVIC of shoulder external and internal rotators significantly increased after real but not sham tDCS. Between-group differences were observed for external and internal rotator muscles. Maximal voluntary isometric contraction of external rotation increased significantly during tDCS, and 30 and 60 minutes post-tDCS for real tDCS compared to that for sham tDCS. For internal rotation MVIC increased significantly during and 60 minutes post-tDCS. The results indicate that transcranial direct current stimulation temporarily increases maximal isometric contractions of the internal and external rotators of the shoulder in handball players. 2.

  7. Effect of slow rhythmic voluntary breathing pattern on isometric handgrip among health care students

    OpenAIRE

    Rajajeyakumar M, Janitha A, Madanmohan, Balachander J

    2014-01-01

    Introduction: Hand grip strength is a widely used test in experimental and epidemiologicalstudies. The measure of hand grip strength is influenced by several factors, including age; gender; different angle of the shoulder, elbow, forearm, and wrist; and posture.So we planned to study theeffect of slow voluntary breathing exercise (Savitri Pranayam) onthe various strengths of isometric hand grip (IHG) amongyoung health care students.Methods: The present study was conducted on 60 volunteers 17-...

  8. Reference values for isometric muscle force among workers for the Netherlands: a comparison of reference values</