Peak torque and knee kinematics during gait after eccentric isokinetic training of quadriceps in healthy subjects O pico de torque e a cinemática do joelho durante a marcha após treino isocinético excêntrico do quadríceps em sujeitos saudáveis

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PR Poletto

2008-08-01

Full Text Available OBJECTIVE: To evaluate the effects of eccentric isokinetic training on knee range of motion (ROM of healthy subjects. METHODS: The knee extensor and flexor isokinetic peak torques and ROM of flexion/extension and varus/valgus knee movements during gait of 18 healthy men (21.7±2.2 years; 1.73±0.10m; 68.7±9.4kg; body mass index: 22.6±2kg/m² were analyzed, before and after six weeks of bilateral eccentric isokinetic training of the knee extensors at 30º/s. RESULTS: The knee extensor torque increased in both limbs (right, from 229±54 to 304±53Nm; pOBJETIVO: Avaliar os efeitos do treino isocinético excêntrico sobre a amplitude de movimento (ADM do joelho em sujeitos saudáveis. MÉTODOS: Foram analisados os picos de torque isocinético dos extensores e flexores do joelho e a ADM de flexo/extensão e valgo/varo, durante a marcha, de 18 homens saudáveis (21,7±2,2 anos; 1,73±0,10m; 68,7±9,4kg; índice de massa corpórea: 22,6±2kg/m² antes e após seis semanas de treino isocinético excêntrico bilateral dos extensores do joelho a 30º/s. RESULTADOS: O torque extensor do joelho aumentou em ambos os membros, direito (de 229±54 para 304±53Nm; p<0,01 e esquerdo (de 228±59 para 311±63Nm; p<0,01 sem diferença de ganho de torque entre eles. O pico de torque flexor aumentou (de 114±30 para 123±22Nm; p<0,05, mas a razão isquiotibiais/quadríceps (I/Q diminuiu (de 0,5±0,08 para 0,39±0,07; p<0,01 após o treino. Não houve diferença para os movimentos de flexo/extensão e valgo/varo após o treino, exceto uma pequena mudança (4° no valgo para o joelho esquerdo. CONCLUSÕES: O treino isocinético excêntrico dos extensores do joelho aumentou o torque extensor e diminuiu a razão I/Q, entretanto o efeito sobre o padrão da marcha parece desprezível em sujeitos saudáveis. Um treino associado dos flexores, complementar ao treino dos extensores parece ser necessário para o equilíbrio entre agonistas e antagonistas do joelho.

Effects of hand grip exercise on shoulder joint internal rotation and external rotation peak torque.

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Lee, Dong-Rour; Jong-Soon Kim, Laurentius

2016-08-10

The goal of this study is to analyze the effects of hand grip training on shoulder joint internal rotation (IR)/external rotation (ER) peak torque for healthy people. The research was conducted on 23 healthy adults in their 20 s-30 s who volunteered to participate in the experiment. Hand grip power test was performed on both hands of the research subjects before/after the test to study changes in hand grip power. Isokinetic machine was used to measure the concentric IRPT (internal rotation peak torque) and concentric ERPT (external rotation peak torque) at the velocity of 60°/sec, 90°/sec, and 180°/sec before/after the test. Hand grip training was performed daily on the subject's right hand only for four weeks according to exercise program. Finally, hand grip power of both hands and the maximum torque values of shoulder joint IR/ER were measured before/after the test and analyzed. There was a statistically significant difference in the hand grip power of the right hand, which was subject to hand grip training, after the experiment. Also, statistically significant difference for shoulder ERPT was found at 60°/sec. Hand grip training has a positive effect on shoulder joint IRPT/ERPT and therefore can help strengthen muscles around the shoulder without using weight on the shoulder. Consequently, hand grip training would help maintain strengthen the muscles around the shoulder in the early phase of rehabilitation process after shoulder surgery.

ACL deficient potential copers and non-copers reveal different isokinetic quadriceps strength profiles in the early stage after injury

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Eitzen, I; Eitzen, TJ; Holm, I; Snyder-Mackler, L; Risberg, MA

2011-01-01

Background Isokinetic muscle strength tests using the peak torque value is the most frequently included quadriceps muscle strength measurement for anterior cruciate ligament (ACL) injured subjects. Aims The purpose of this study was to investigate quadriceps muscle performance during the whole isokinetic curve in ACL deficient subjects classified as potential copers or non-copers, and investigate whether these curve profiles were associated with single-leg hop performance. We hypothesized that quadriceps muscle torque at other knee flexion angles than peak torque would give more information about quadriceps muscle strength deficits. Furthermore, we hypothesized that there would be significant torque differences between potential copers and non-copers, and a significant relationship between angle specific torque values and single-leg hop performance. Study Design Cross-sectional study; Level of evidence, 2 Methods Seventy-six individuals with a complete unilateral ACL rupture within the last 3 months were included. The subjects were classified into potential copers and non-copers according to the criteria from Fitzgerald et al12. Isokinetic quadriceps muscle tests were performed at 60°/sec (Biodex 6000). Mean torque values were calculated for peak torque as well as for specific knee flexion angles. The one-leg hop and the 6 meter timed hop tests were included and symmetry indices were used. Results The peak torque value did not identify the largest quadriceps muscle strength deficit. Rather, these were established at knee flexion angles of less than 40°. There were significant differences in angle specific torque values between potential copers and non-copers (p<0.05). Moderate to strong associations were disclosed between angle specific torque values and single-leg hop performance, but only for non-copers (r≥0.32– 0.58). Conclusions Angle specific quadriceps muscle torque values of less than 40° of knee flexion provide more information on the quadriceps

Multilevel Models for the Analysis of Angle-Specific Torque Curves with Application to Master Athletes

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Carvalho Humberto M.

2015-12-01

Full Text Available The aim of this paper was to outline a multilevel modeling approach to fit individual angle-specific torque curves describing concentric knee extension and flexion isokinetic muscular actions in Master athletes. The potential of the analytical approach to examine between individual differences across the angle-specific torque curves was illustrated including between-individuals variation due to gender differences at a higher level. Torques in concentric muscular actions of knee extension and knee extension at 60°·s-1 were considered within a range of motion between 5°and 85° (only torques “truly” isokinetic. Multilevel time series models with autoregressive covariance structures with standard multilevel models were superior fits compared with standard multilevel models for repeated measures to fit anglespecific torque curves. Third and fourth order polynomial models were the best fits to describe angle-specific torque curves of isokinetic knee flexion and extension concentric actions, respectively. The fixed exponents allow interpretations for initial acceleration, the angle at peak torque and the decrement of torque after peak torque. Also, the multilevel models were flexible to illustrate the influence of gender differences on the shape of torque throughout the range of motion and in the shape of the curves. The presented multilevel regression models may afford a general framework to examine angle-specific moment curves by isokinetic dynamometry, and add to the understanding mechanisms of strength development, particularly the force-length relationship, both related to performance and injury prevention.

Influence of functional knee bracing on the isokinetic and functional tests of anterior cruciate ligament deficient patients.

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Niyousha Mortaza

Full Text Available Use of functional knee braces has been suggested to provide protection and to improve kinetic performance of the knee in Anterior cruciate ligament(ACL-injured patients. However, many athletes might refrain from wearing the braces because of the fear of performance hindrance in the playing field. The aim of this study was to examine the effect of three functional knee brace/sleeves upon the isokinetic and functional performance of ACL-deficient and healthy subjects. Six anterior cruciate ligament deficient (29.0 ± 5.3 yrs., 175.2 ± 5.4 cm, and 73.0 ± 10.0 kg and six healthy male subjects (27.2 ± 3.7 yrs., 176.4 ± 6.4 cm, and 70.3 ± 6.9 kg were selected. The effect of a custom-made functional knee brace, and two neoprene knee sleeves, one with four metal supports and one without support were examined via the use of isokinetic and functional tests in four sets (non-braced,wearing functional knee brace,and wearing the sleeves. Cross-over hop and single leg vertical jump test were performed and jump height, and hop distance were recorded. Peak torque to body weight ratio and average power in two isokinetic velocities(60°.s(-1,180°.s(-1 were recorded and the brace/sleeves effect was calculated as the changes in peak torque measured in the brace/sleeves conditions, expressed as a percentage of peak torque measured in non-braced condition. Frequency content of the isokinetic torque-time curves was also analyzed. Wilcoxon signed rank test was used to compare the measured values in four test conditions within each control and ACL-deficient group,and Mann-Whitney U test was used for the comparison between the two groups. No significant differences in peak torque, average power, torque-time curve frequency content, vertical-jump and hop measurements were found within the experimental and the non-braced conditions (p>0.05. Although the examined functional knee brace/sleeves had no significant effect on the knee muscle performance, there have been

Isokinetic assessment of knee flexor/extensor muscular strength in elderly women Avaliação isocinética do torque muscular flexor-extensor do joelho em mulheres com idade entre 75-83 anos

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Marcos de Amorim Aquino

2002-08-01

Full Text Available OBJECTIVE: To assess knee flexor-extensor muscular strength in elderly women with no previous history of musculoskeletal disorders on the lower limbs using an isokinetic dynamometer, in order to obtain data that could be used as a comparative parameter in the evaluation of elderly women with knee disorders, thus facilitating a better rehabilitation of these patients. METHODS: Twenty-six volunteers aged 75 to 83 years were studied using a Cybex® 6000 isokinetic dynamometer. The chosen angular velocity was 60 º/s, and concentric exercise was used for either flexion or extension. The studied parameters were: peak torque, angle of peak torque, and flexor-extensor torque rate. RESULTS: There were no differences between dominant (D and nondominant (ND knee peak torque values. This was true for both flexor (D = 42.46 ± 9.09 Nm / ND = 40.65 ± 9.38 Nm and extensor (D = 76.92 ± 13.97 Nm / ND = 77.65 ± 15.21 Nm movements. The descriptive statistical analysis of the values obtained for the flexor-extensor peak torque rate and for the angle of occurrence of peak torque was the same for the dominant and nondominant sides. CONCLUSIONS: The values of peak torque for the contralateral side can be used as a reference during rehabilitation of elderly women with acute disease of the knee, and the angular velocity of 60 º/s is proper and safe for isokinetic assessment of elderly people.OBJETIVO: Avaliar, isocineticamente, o torque dos músculos flexores e extensores dos joelhos de mulheres idosas sem afecções do sistema músculo-esquelético em membros inferiores, obtendo dados que possam servir como parâmetro de comparação na avaliação de mulheres idosas portadoras de afecções nos joelhos, colaborando para uma melhor reabilitação dessas pacientes. CASUÍSTICA E MÉTODOS: Vinte e seis voluntárias foram avaliadas. O estudo foi realizado através de um dinamômetro isocinético marca CYBEXâ modelo 6000 na velocidade angular de 60º/s. O tipo do

Assessment of isokinetic knee strength in elite young female basketball players: correlation with vertical jump.

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Rouis, M; Coudrat, L; Jaafar, H; Filliard, J-R; Vandewalle, H; Barthelemy, Y; Driss, T

2015-12-01

To explore the isokinetic concentric strength of the knee muscle groups, and the relationship between the isokinetic knee extensors strength and the vertical jump performance in young elite female basketball players. Eighteen elite female basketball players performed a countermovement jump, and an isokinetic knee test using a Biodex dynamometer. The maximal isokinetic peak torque of the knee extensor and flexor muscles was recorded at four angular velocities (90°/s, 180°/s, 240°/s and 300°/s) for the dominant and non-dominant legs. The conventional hamstring/quadriceps ratio (H/Q) was assessed at each angular velocity for both legs. There was no significant difference between dominant and non-dominant leg whatever the angular velocity (all P>0.05). However, the H/Q ratio enhanced as the velocity increased from 180°/s to 300°/s (Pvertical jump height. The highest one was found for the knee extensors peak torque at a velocity of 240°/s (r=0.88, Pvertical jump height. Interestingly, the H/Q ratio of the young elite female basketball players in the present study was unusual as it was close to that generally observed in regular sportsmen.

KNEE ISOKINETIC TORQUE IMBALANCE IN FEMALE FUTSAL PLAYERS

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Ana Carolina de Mello Alves Rodrigues

Full Text Available ABSTRACT Introduction: The specificity of sports training can lead to muscle specialization with a possible change in the natural hamstring/quadriceps torque ratio (HQ ratio, constituting a risk factor for muscle injury at the joint angles in which muscle imbalance may impair dynamic stability. Objective: The aim was to evaluate the torque distribution of the hamstrings and quadriceps and the HQ ratio throughout the range of motion in order to identify possible muscle imbalances at the knee of female futsal athletes. Methods: Nineteen amateur female futsal athletes had their dominant limb HQ ratio evaluated in a series of five maximum repetitions of flexion/extension of the knee at 180°/second in the total joint range of motion (30° to 80°. The peak flexor and extensor torque and the HQ ratio (% were compared each 5° of knee motion using one-way repeated measures ANOVA and Tukey’s post hoc test (p<0.05 to determine the joint angles that present muscular imbalance. Results: Quadriceps torque was higher than 50° to 60° of knee flexion, while hamstrings torque was higher than 55° to 65°. The HQ ratio presented lower values than 30° to 45° of knee flexion and four athletes presented values lower than 60%, which may represent a risk of injury. However, the HQ ratio calculated by the peak torque showed only one athlete with less than 60%. Conclusion: The HQ ratio analyzed throughout the knee range of motion allowed identifying muscle imbalance at specific joint angles in female futsal players.

Peak torque and rate of torque development in elderly with and without fall history.

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Bento, Paulo Cesar Barauce; Pereira, Gleber; Ugrinowitsch, Carlos; Rodacki, André Luiz Felix

2010-06-01

Falls are one of the greatest concerns among the elderly. A number of studies have described peak torque as one of the best fall-related predictor. No studies have comprehensively focused on the rate of torque development of the lower limb muscles among elderly fallers. Then, the aim of this study was to determine the relationship between muscle peak torque and rate of torque development of the lower limb joints in elderly with and without fall history. It was also aimed to determine whether these parameters of muscle performance (i.e., peak torque and rate of torque development) are related to the number of falls. Thirty-one women volunteered to participate in the study and were assigned in one of the groups according to the number of falls over the 12 months that preceded the present. Then, participants with no fall history (GI; n=13; 67.6[7.5] years-old), one fall (GII; n=8; 66.0[4.9] years-old) and two or more falls (GIII; n=10; 67.8[8.8] years-old) performed a number of lower limb maximal isometric voluntary contractions from which peak torque and rate of torque development were quantified. Primary outcomes indicated no peak torque differences between experimental groups in any lower limb joint. The rate of torque development of the knee flexor muscles observed in the non-fallers (GI) was greater than that observed in the fallers (Pfalls (Pelderly to rapidly reorganise the arrangement of the lower limb may play a significant role in allowing the elderly to recover balance after a trip. Thus, training stimulus aimed to improve the rate of torque development may be more beneficial to prevent falls among the elderly than other training stimulus, which are not specifically designed to improve the ability to rapidly produce large amounts of torque. Copyright (c) 2010. Published by Elsevier Ltd.

Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.

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Melo, Ruth C; Takahashi, Anielle C M; Quitério, Robison J; Salvini, Tânia F; Catai, Aparecida M

2016-01-01

Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p torque was the only exercise tested that showed an interaction effect between age and muscle length (p torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.

Association with isokinetic ankle strength measurements and normal clinical muscle testing in sciatica patients.

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Ustun, N; Erol, O; Ozcakar, L; Ceceli, E; Ciner, O Akar; Yorgancioglu, Z R

2013-01-01

Sensitive muscle strength tests are needed to measure muscle strength in the diagnosis and management of sciatica patients. The aim of this study was to assess the isokinetic muscle strength in sciatica patients' and control subjects' ankles that exhibited normal ankle muscle strength when measured clinically. Forty-six patients with L5 and/or S1 nerve compression, and whose age, sex, weight, and height matched 36 healthy volunteers, were recruited to the study. Heel-walking, toe-walking, and manual muscle testing were used to perform ankle dorsiflexion and plantar flexion strengths in clinical examination. Patients with normal ankle dorsiflexion and plantar flexion strengths assessed by manual muscle testing and heel-and toe-walking tests were included in the study. Bilateral isokinetic (concentric/concentric) ankle plantar-flexion-dorsiflexion measurements of the patients and controls were performed within the protocol of 30°/sec (5 repetitions). Peak torque and peak torque/body weight were obtained for each ankle motion of the involved limb at 30°/s speed. L5 and/or S1 nerve compression was evident in 46 patients (76 injured limbs). Mean disease duration was two years. The plantar flexion muscle strength of the patients was found to be lower than that of the controls (p=0.036). The dorsiflexion muscle strength of the patients was found to be the same as that of the controls (p=0.211). Isokinetic testing is superior to clinical muscle testing when evaluating ankle plantar flexion torque in sciatica patients. Therefore, isokinetic muscle testing may be helpful when deciding whether to place a patient into a focused rehabilitation program.

Comparison of isokinetic muscle strength and muscle power by types of warm-up.

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Sim, Young-Je; Byun, Yong-Hyun; Yoo, Jaehyun

2015-05-01

[Purpose] The purpose of this study was to clarify the influence of static stretching at warm-up on the isokinetic muscle torque (at 60°/sec) and muscle power (at 180°/sec) of the flexor muscle and extensor muscle of the knee joint. [Subjects and Methods] The subjects of this study were 10 healthy students with no medically specific findings. The warm-up group and warm-up with stretching group performed their respective warm-up prior to the isokinetic muscle torque evaluation of the knee joint. One-way ANOVA was performed by randomized block design for each variable. [Results] The results were as follows: First, the flexor peak torque and extensor peak torque of the knee joint tended to decrease at 60°/sec in the warm-up with stretching group compared with the control group and warm-up group, but without statistical significance. Second, extensor power at 180°/sec was also not statistically significant. However, it was found that flexor power increased significantly in the warm-up with stretching group at 180°/sec compared with the control group and warm-up group in which stretching was not performed. [Conclusion] Therefore, it is considered that in healthy adults, warm-up including two sets of stretching for 20 seconds per muscle group does not decrease muscle strength and muscle power.

The isokinetic strength profile of elite soccer players according to playing position.

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Robert Śliwowski

Full Text Available The aim of this study was to compare isokinetic strength performance profiles in elite soccer players across different field positions. A total of 111 elite international players of Polish Ekstraklasa (the top division in Poland were examined during the 2010-2015 seasons. The players were classified into six positional roles: central defenders (CD, external defenders (ED, central midfielders (CM, external midfielders (EM, forwards (F, and goalkeepers (G. The concentric isokinetic strength (peak torque [PT] of quadriceps and hamstrings, H/Q ratios was calculated for the dominant leg and the non-dominant leg at angular velocity of 1.05 rad ·s-1, whereas to assess isokinetic muscle endurance, the total work [TW] at angular velocity of 4.19 rad ·s-1, was taken into consideration. The results showed that isokinetic strength performance varies significantly among players in different playing positions. The analysis of PT for quadriceps (PT-Q and hamstrings (PT-H generally showed that the goalkeepers and central midfielders had lower strength levels compared to other playing positions. In the case of PT-H and hamstring/quadricep (H/Q peak torque ratios, statistically significant differences were also noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg. For TW for quadriceps (TW-Q and hamstrings (TW-H, statistically significant differences were noted only between playing positions. TW-Q values for goalkeepers were lower than for central defenders and external midfielders. TW-H values for goalkeepers were lower than for central midfielders, central defenders and external midfielders. This study showed that specific functional activity of players in individual positions on the field influences the varied profile of isokinetic strength performance.

Interseason variability in isokinetic strength and poor correlation with Nordic hamstring eccentric strength in football players.

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van Dyk, N; Witvrouw, E; Bahr, R

2018-04-25

In elite sport, the use of strength testing to establish muscle function and performance is common. Traditionally, isokinetic strength tests have been used, measuring torque during concentric and eccentric muscle action. A device that measures eccentric hamstring muscle strength while performing the Nordic hamstring exercise is now also frequently used. The study aimed to investigate the variability of isokinetic muscle strength over time, for example, between seasons, and the relationship between isokinetic testing and the new Nordic hamstring exercise device. All teams (n = 18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Qatar. Isokinetic strength was investigated for measurement error, and correlated to Nordic hamstring exercise strength. Of the 529 players included, 288 players had repeated tests with 1/2 seasons between test occasions. Variability (measurement error) between test occasions was substantial, as demonstrated by the measurement error (approximately 25 Nm, 15%), whether separated by 1 or 2 seasons. Considering hamstring injuries, the same pattern was observed among injured (n = 60) and uninjured (n = 228) players. A poor correlation (r = .35) was observed between peak isokinetic hamstring eccentric torque and Nordic hamstring exercise peak force. The strength imbalance between limbs calculated for both test modes was not correlated (r = .037). There is substantial intraindividual variability in all isokinetic test measures, whether separated by 1 or 2 seasons, irrespective of injury. Also, eccentric hamstring strength and limb-to-limb imbalance were poorly correlated between the isokinetic and Nordic hamstring exercise tests. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The Relationship between Isokinetic Relative Torque of Hip, Knee and Ankle Joints and the Height of Guide Leg Jump in Young Men

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Saeed Nikoukheslat

2016-06-01

Full Text Available Objective: The aim of this study was to investigate the relationship between isokinetic relative torques of hip, knee and ankle joints and the height of guide leg jump in young men. Methods: 27 college male athletes with mean age of 25±3.5 years, height 178.5±7.8 cm and weight of 75.7±10.7 kg voluntarily participated in this study. Isokinetic torque of hip, knee and ankle joints and the height of vertical jump were measured using BIODEX SYSTEM PRO 4 and digital vertical jumping tester systems respectively. Pearson correlation test at p<0.05 was used for statistical analysis. Results: Results showed that there were significant correlations between height of jump and hip joint flexion (p= 0.047 & r= 0.39 and extension (p= 0.003 & r= 0.55 torques of guide leg, hip joint extension torque of support leg (p= 0.020 & r=0.45 and knee joint flexion (p= 0.019 & r=0.45 and extension torques of support leg (p=0.006 & r=0.52. Conclusion: The results of this study show that flexion and extension torques of hip joint in guide leg and knee joint in support leg and also extension torque of hip joint in support leg have main effect on height of guide leg jump. Thus, in designing a specific training program for athletes in whom the nature of jump in their sports is guide leg jump, particular attention should be given to hip and knee joints strength.

Rotational and peak torque stiffness of rugby shoes.

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Ballal, Moez S; Usuelli, Federico Giuseppe; Montrasio, Umberto Alfieri; Molloy, Andy; La Barbera, Luigi; Villa, Tomaso; Banfi, Giuseppe

2014-09-01

Sports people always strive to avoid injury. Sports shoe designs in many sports have been shown to affect traction and injury rates. The aim of this study is to demonstrate the differing stiffness and torque in rugby boots that are designed for the same effect. Five different types of rugby shoes commonly worn by scrum forwards were laboratory tested for rotational stiffness and peak torque on a natural playing surface generating force patterns that would be consistent with a rugby scrum. The overall internal rotation peak torque was 57.75±6.26 Nm while that of external rotation was 56.55±4.36 Nm. The Peak internal and external rotational stiffness were 0.696±0.1 and 0.708±0.06 Nm/deg respectively. Our results, when compared to rotational stiffness and peak torques of football shoes published in the literature, show that shoes worn by rugby players exert higher rotational and peak torque stiffness compared to football shoes when tested on the same natural surfaces. There was significant difference between the tested rugby shoes brands. In our opinion, to maximize potential performance and lower the potential of non-contact injury, care should be taken in choosing boots with stiffness appropriate to the players main playing role. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hyperventilation-induced respiratory alkalosis falls short of countering fatigue during repeated maximal isokinetic contractions.

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Sakamoto, Akihiro; Naito, Hisashi; Chow, Chin Moi

2015-07-01

Hyperventilation, implemented during recovery of repeated maximal sprints, has been shown to attenuate performance decrement. This study evaluated the effects of hyperventilation, using strength exercises, on muscle torque output and EMG amplitude. Fifteen power-trained athletes underwent maximal isokinetic knee extensions consisting of 12 repetitions × 8 sets at 60°/s and 25 repetitions × 8 sets at 300°/s. The inter-set interval was 40 s for both speeds. For the control condition, subjects breathed spontaneously during the interval period. For the hyperventilation condition, subjects hyperventilated for 30 s before each exercise set (50 breaths/min, PETCO2: 20-25 mmHg). EMG was recorded from the vastus medialis and lateralis muscles to calculate the mean amplitude for each contraction. Hyperventilation increased blood pH by 0.065-0.081 and lowered PCO2 by 8.3-10.3 mmHg from the control values (P < 0.001). Peak torque declined with repetition and set numbers for both speeds (P < 0.001), but the declining patterns were similar between conditions. A significant, but small enhancement in peak torque was observed with hyperventilation at 60°/s during the initial repetition phase of the first (P = 0.032) and fourth sets (P = 0.040). EMG amplitude also declined with set number (P < 0.001) for both speeds and muscles, which was, however, not attenuated by hyperventilation. Despite a minor ergogenic effect in peak torque at 60°/s, hyperventilation was not effective in attenuating the decrement in torque output at 300°/s and decrement in EMG amplitude at both speeds during repeated sets of maximal isokinetic knee extensions.

Isokinetic Testing in Evaluation Rehabilitation Outcome After ACL Reconstruction.

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Cvjetkovic, Dragana Dragicevic; Bijeljac, Sinisa; Palija, Stanislav; Talic, Goran; Radulovic, Tatjana Nozica; Kosanovic, Milkica Glogovac; Manojlovic, Slavko

2015-02-01

Numerous rehab protocols have been used in rehabilitation after ACL reconstruction. Isokinetic testing is an objective way to evaluate dynamic stability of the knee joint that estimates the quality of rehabilitation outcome after ACL reconstruction. Our investigation goal was to show importance of isokinetic testing in evaluation thigh muscle strength in patients which underwent ACL reconstruction and rehabilitation protocol. In prospective study, we evaluated 40 subjects which were divided into two groups. Experimental group consisted of 20 recreational males which underwent ACL reconstruction with hamstring tendon and rehabilitation protocol 6 months before isokinetic testing. Control group (20 subjects) consisted of healthy recreational males. In all subjects knee muscle testing was performed on a Biodex System 4 Pro isokinetic dynamo-meter et velocities of 60°/s and 180°/s. We followed average peak torque to body weight (PT/BW) and classic H/Q ratio. In statistical analysis Student's T test was used. There were statistically significant differences between groups in all evaluated parameters except of the mean value of PT/BW of the quadriceps et velocity of 60°/s (p>0.05). Isokinetic testing of dynamic stabilizers of the knee is need in diagnostic and treatment thigh muscle imbalance. We believe that isokinetic testing is an objective parameter for return to sport activities after ACL reconstruction.

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

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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.

Single-Leg Hop Test Performance and Isokinetic Knee Strength After Anterior Cruciate Ligament Reconstruction in Athletes.

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Sueyoshi, Ted; Nakahata, Akihiro; Emoto, Gen; Yuasa, Tomoki

2017-11-01

Isokinetic strength and hop tests are commonly used to assess athletes' readiness to return to sport after knee surgery. The purpose of this study was to investigate the results of single-leg hop and isokinetic knee strength testing in athletes who underwent anterior cruciate ligament reconstruction (ACLR) upon returning to sport participation as well as to study the correlation between these 2 test batteries. The secondary purpose was to compare the test results by graft type (patellar tendon or hamstring). It was hypothesized that there would be no statistically significant limb difference in either isokinetic knee strength or single-leg hop tests, that there would be a moderate to strong correlation between the 2 test batteries, and that there would be no significant difference between graft types. Cross-sectional study; Level of evidence, 3. Twenty-nine high school and collegiate athletes who underwent ACLR participated in this study. At the time of return to full sport participation, a series of hop tests and knee extension/flexion isokinetic strength measurements were conducted. The results were analyzed using analysis of variance and Pearson correlation ( r ). The timed 6-m hop test was the only hop test that showed a significant difference between the involved and uninvolved limbs (2.3 and 2.2 seconds, respectively; P = .02). A significant difference between limbs in knee strength was found for flexion peak torque/body weight at 180 deg/s ( P = .03), flexion total work/body weight at 180 deg/s ( P = .04), and flexion peak torque/body weight at 300 deg/s ( P = .03). The strongest correlation between the hop tests and knee strength was found between the total distance of the hop tests and flexion total work/body weight at 300 deg/s ( r = 0.69) and between the timed 6-m hop test and flexion peak torque/body weight at 300 deg/s ( r = -0.54). There was no statistically significant difference in hop test performance or isokinetic knee strength between graft types

Isokinetic muscle performance of the hip and ankle muscles in women with fibromyalgia.

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Yetişgin, Alparslan; Tiftik, Tülay; Kara, Murat; Karabay, İlkay; Akkuş, Selami; Ersöz, Murat

2016-06-01

To compare isokinetic muscle performances of a proximal (hip) and a distal (ankle) muscle of fibromyalgia syndrome (FMS) patients with those of age- and body mass index (BMI)-matched healthy subjects. Thirty female patients with FMS (mean age: 41.5 ± 6.7 years [range, 27-54]) and 30 age- (mean age: 40.6 ± 6.0 years [range, 27-54]) and BMI-matched female healthy controls were consecutively enrolled. Demographic and clinical characteristics of the subjects were recorded. Isokinetic measurements of hip and ankle flexion and extension at angular velocities of 60°/s and 180°/s, peak torques, flexor-extensor torque ratios, muscle fatigue resistance values and average power were obtained. Mean disease duration of FMS patients was 2.4 ± 1.9 years. Mean weight, height and BMI values were 70.4 ± 12.5 kg, 159.5 ± 6.0 cm and 27.7 ± 4.7 kg/m² (FMS patients) and 69.3 ± 10.1 kg, 161.7 ± 6.2 cm and 26.6 ± 4.3 kg/m² (control subjects), respectively (all P > 0.05). All isokinetic values were statistically decreased in the FMS group when compared with the control group, except for the peak torques at angular velocity of 180°/s on flexion of the hip and extension of the ankle and the total work and average power on extension of the ankle. We did not find any correlation between isokinetic values and disease related parameters of FMS patients. In the light of our results, we may conclude that muscle strength and muscle fatigue seem to decrease in FMS patients' both proximal and distal lower extremity muscles. © 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

Efficacy of isokinetic exercise on functional capacity and pain in patellofemoral pain syndrome.

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Alaca, Ridvan; Yilmaz, Bilge; Goktepe, A Salim; Mohur, Haydar; Kalyon, Tunc Alp

2002-11-01

To assess the effect of an isokinetic exercise program on symptoms and functions of patients with patellofemoral pain syndrome. A total of 22 consecutive patients with the complaint of anterior knee pain who met the inclusion criteria were recruited to assess the efficacy of isokinetic exercise on functional capacity, isokinetic parameters, and pain scores in patients with patellofemoral pain syndrome. A total of 37 knees were examined. Six-meter hopping, three-step hopping, and single-limb hopping course tests were performed for each patient with the measurements of the Lysholm scale and visual analog scale. Tested parameters were peak torque, total work, average power, and endurance ratios. Statistical analyses revealed that at the end of the 6-wk treatment period, functional and isokinetic parameters improved significantly, as did pain scores. There was not statistically significant correlation between different groups of parameters. The isokinetic exercise treatment program used in this study prevented the extensor power loss due to patellofemoral pain syndrome, but the improvement in the functional capacity was not correlated with the gained power.

Isokinetic torque peak and hamstrings/quadriceps ratios in endurance athletes with anterior cruciate ligament laxity Pico de torque isocinético e relação ísquios-tibiais/quadríceps em atletas de endurance com frouxidão do ligamento cruzado anterior

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Eliane Magaieski Portes

2007-01-01

Full Text Available PURPOSE: To evaluate torque and the hamstring/quadriceps ratio of the knee of athletes with and without anterior cruciate ligament laxity. METHODS: Twenty-eight male athletes, 19 without anterior cruciate ligament laxity and 9 with anterior cruciate ligament laxity, were evaluated with an isokinetic machine model Cybex 770. The peak torque of quadriceps and hamstrings was compared, and the hamstring/quadriceps ratio on the constant angular speed of 60º per second were also compared. RESULTS: In athletes with anterior cruciate ligament laxity, the peak torque values (right and left knees of flexors (120 ± 15 and 116 ± 15 Nm and of extensors (218 ± 36 Nm and 207 ± 26 Nm were not different than those of athletes without laxity (109 ± 21 Nm and 111 ± 22 Nm; 191 ± 5 Nm and 188 ± 35 Nm. The hamstring/quadriceps ratio of athletes with laxity (right: 57 ± 6% and left: 56 ± 8% did not differ from those without anterior cruciate ligament laxity (right: 58 ± 9% and left: 58 ± 7%. CONCLUSIONS: The anterior cruciate ligament laxity of long distances running athletes did not significantly alter the peak torque of flexors and of extensors or the hamstring/quadriceps ratio.OBJETIVO: Avaliar o torque e a relação de forças entre ísquios-tibiais/quadríceps dos joelhos de atletas corredores de longas distâncias com e sem frouxidão do ligamento cruzado anterior. METODOLOGIA: Vinte e oito atletas do gênero masculino, 19 sem frouxidão do ligamento cruzado anterior e 9 com frouxidão do ligamento cruzado anterior foram avaliados com aparelho isocinético modelo Cybex 770. Comparou-se o pico de torque dos quadríceps e dos ísquios-tibiais e a relação ísquios-tibiais/quadríceps na velocidade angular constante de 60º por segundo. Os dados obtidos foram comparados por meio dos testes t de Student e para dados pareados (membros direito e esquerdo e o nível de significância estabelecido foi p < 0,05. RESULTADOS: Nos atletas com frouxidão do

A Ground-Based Comparison of the Muscle Atrophy Research and Exercise System (MARES) and a Standard Isokinetic Dynamometer

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Hackney, K. J.; English, K. L.; Redd, E.; DeWitt, J. K.; Ploutz-Snyder, R.; Ploutz-Snyder, L. L.

2010-01-01

PURPOSE: 1) To compare the test-to-test reliability of Muscle Atrophy Research and Exercise System (MARES) with a standard laboratory isokinetic dynamometer (ISOK DYN) and; 2) to determine if measures of peak torque and total work differ between devices. METHODS: Ten subjects (6M, 4F) completed two trials on both MARES and an ISOK DYN in a counterbalanced order. Peak torque values at 60 deg & 180 deg / s were obtained from five maximal repetitions of knee extension (KE) and knee flexion (KF). Total work at 180 deg / s was determined from the area under the torque vs. displacement curve during twenty maximal repetitions of KE and KF. Reliability of measures within devices was interpreted from the intraclass correlation coefficient (ICC) and compared between devices using the ratio of the within-device standard deviations. Indicators of agreement for the two devices were evaluated from: 1) a calculation of concordance (rho) and; 2) the correlation between the mean of measures versus the delta difference between measures (m u vs delta). RESULTS: For all outcome measures ICCs were high for both the ISOK DYN (0.95-0.99) and MARES (0.90-0.99). However, ratios of the within-device standard deviation were 1.3 to 4.3 times higher on MARES. On average, a wide range (3.3 to 1054 Nm) of differences existed between the values obtained. Only KE peak torque measured at 60 deg & 180 deg / s showed similarities between devices (rho = 0.91 & 0.87; Pearson's r for m u vs delta = -0.22 & -0.37, respectively). CONCLUSION: Although MARES was designed for use in microgravity it was quite reliable during ground-based testing. However, MARES was consistently more variable than an ISOK DYN. Future longitudinal studies evaluating a change in isokinetic peak torque or total work should be limited within one device.

Isokinetic Strength Profile of Elite Female Handball Players

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Xaverova Zuzana

2015-12-01

Full Text Available Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women’s Junior National Handball Team (JNT, n=8 or the Women’s National Handball Team (NT, n=9. The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric and 60°/s (eccentric. The Mann- Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02. However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

Isokinetic Strength Profile of Elite Female Handball Players.

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Xaverova, Zuzana; Dirnberger, Johannes; Lehnert, Michal; Belka, Jan; Wagner, Herbert; Orechovska, Karolina

2015-12-22

Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women's Junior National Handball Team (JNT, n=8) or the Women's National Handball Team (NT, n=9). The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric) and 60°/s (eccentric). The Mann-Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD) for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02). However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

Relation between isokinetic muscle strength and functional capacity in recreational athletes with chondromalacia patellae.

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Yildiz, Y; Aydin, T; Sekir, U; Cetin, C; Ors, F; Alp Kalyon, T

2003-12-01

To investigate the effects of isokinetic exercise on pain and functional test scores of recreational athletes with chondromalacia patellae (CMP) and to examine the correlation between isokinetic parameters and functional tests or pain score. The functional ability of 30 recreational athletes with unilateral CMP was evaluated using six different tests. Pain scores were assessed during daily activities before and after the treatment protocol. Isokinetic exercise sessions were carried out at angular velocities of 60 degrees /s (25-90 degrees range of flexion) and 180 degrees /s (full range). These sessions were repeated three times a week for six weeks. Quadriceps and hamstring peak torque, total work, and endurance ratios had improved significantly after the treatment, as did the functional parameters and pain scores. There was a poor correlation between the extensor endurance ratio and one leg standing test. A moderate correlation between the visual analogue scale and the extensor endurance ratio or flexion endurance ratio was also found. The isokinetic exercise programme used in this study had a positive effect on muscle strength, pain score, and functional ability of knees with CMP. The improvement in the functional capacity did not correlate with the isokinetic parameters.

Selected isokinetic tests in knee injury prevention

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W Pilis

2010-03-01

Full Text Available Ensuing from isokinetic measurements, the conventional Hcon/Qcon ratio of muscle balance is used as an index for comparing proper relations between the values of strength of knee flexors and extensor muscle. Its abnormal values might indicate pathology of the musculotendinous complex. The aim of the study was to present the possibility of using this ratio as one of the objective identifiers enabling the assessment of knee injury risk in sports. All participants (n=48 were divided into 3 groups: group A (n=16, healthy competitors, group B (n=16, athletes with minor injuries, group C (n=16, competitors with serious injuries, depending on the degree of knee injury. All subjects performed an isokinetic test for knee extensors and flexors at angular velocities of 60°/s and 120°/s. Average peak torque (APT value of knee flexors and extensors, and the value of Hcon/Qcon ratio was analyzed. Both values were calculated in relation to body mass (Nm/kg. Bilateral comparison of isokinetic test parameters confirmed the decrease of quadriceps muscle strength values for the injured extremity in groups B and C. Statistically significant difference was noted for Hcon/Qcon ratio between group A and C, as well as B and C. Hence, the value of conventional Hcon/Qcon ratio can be used for the prevention of sports related injuries.

Relative differences in strength and power from slow to fast isokinetic velocities may reflect dynapenia.

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Jenkins, Nathaniel D M; Housh, Terry J; Palmer, Ty B; Cochrane, Kristen C; Bergstrom, Haley C; Johnson, Glen O; Schmidt, Richard J; Cramer, Joel T

2015-07-01

We compared absolute and normalized values for peak torque (PT), mean power (MP), rate of velocity development, and electromyography (EMG) amplitude during maximal isometric and concentric isokinetic leg extension muscle actions, as well as the %decrease in PT and %increase in MP from 1.05 to 3.14 rad·s(-1) in younger versus older men. Measurements were performed twice for reliability. Isokinetic measurements were normalized to the isometric muscle actions. Absolute isometric PT, isokinetic PT and MP, and EMG amplitudes at 1.05 and 3.14 rad·s(-1) were greater in the younger men, although normalizing to isometric PT eliminated the age differences. The older men exhibited greater %decrease in PT (37.2% vs. 31.3%) and lower %increase in MP (87.6% vs. 126.4%) regardless of normalization. Normalization eliminated absolute differences in isokinetic strength and power, but the relative differences from slow to fast velocities may reflect dynapenia characterized by age-related decreases in fast-twitch fiber function. © 2014 Wiley Periodicals, Inc.

Isometric and isokinetic hip strength and agonist/antagonist ratios in symptomatic femoroacetabular impingement.

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Diamond, Laura E; Wrigley, Tim V; Hinman, Rana S; Hodges, Paul W; O'Donnell, John; Takla, Amir; Bennell, Kim L

2016-09-01

This study investigated isometric and isokinetic hip strength in individuals with and without symptomatic femoroacetabular impingement (FAI). The specific aims were to: (i) determine whether differences exist in isometric and isokinetic hip strength measures between groups; (ii) compare hip strength agonist/antagonist ratios between groups; and (iii) examine relationships between hip strength and self-reported measures of either hip pain or function in those with FAI. Cross-sectional. Fifteen individuals (11 males; 25±5 years) with symptomatic FAI (clinical examination and imaging (alpha angle >55° (cam FAI), and lateral centre edge angle >39° and/or positive crossover sign (combined FAI))) and 14 age- and sex-matched disease-free controls (no morphological FAI on magnetic resonance imaging) underwent strength testing. Maximal voluntary isometric contraction strength of hip muscle groups and isokinetic hip internal (IR) and external rotation (ER) strength (20°/s) were measured. Groups were compared with independent t-tests and Mann-Whitney U tests. Participants with FAI had 20% lower isometric abduction strength than controls (p=0.04). There were no significant differences in isometric strength for other muscle groups or peak isokinetic ER or IR strength. The ratio of isometric, but not isokinetic, ER/IR strength was significantly higher in the FAI group (p=0.01). There were no differences in ratios for other muscle groups. Angle of peak IR torque was the only feature correlated with symptoms. Individuals with symptomatic FAI demonstrate isometric hip abductor muscle weakness and strength imbalance in the hip rotators. Strength measurement, including agonist/antagonist ratios, may be relevant for clinical management of FAI. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Validity and reliability of isometric, isokinetic and isoinertial modalities for the assessment of quadriceps muscle strength in patients with total knee arthroplasty.

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Lienhard, K; Lauermann, S P; Schneider, D; Item-Glatthorn, J F; Casartelli, N C; Maffiuletti, N A

2013-12-01

Reliability of isometric, isokinetic and isoinertial modalities for quadriceps strength evaluation, and the relation between quadriceps strength and physical function was investigated in 29 total knee arthroplasty (TKA) patients, with an average age of 63 years. Isometric maximal voluntary contraction torque, isokinetic peak torque, and isoinertial one-repetition maximum load of the involved and uninvolved quadriceps were evaluated as well as objective (walking parameters) and subjective physical function (WOMAC). Reliability was good and comparable for the isometric, isokinetic, and isoinertial strength outcomes on both sides (intraclass correlation coefficient range: 0.947-0.966; standard error of measurement range: 5.1-9.3%). Involved quadriceps strength was significantly correlated to walking speed (r range: 0.641-0.710), step length (r range: 0.685-0.820) and WOMAC function (r range: 0.575-0.663), independent from the modality (P strength was also significantly correlated to walking speed (r range: 0.413-0.539), step length (r range: 0.514-0.608) and WOMAC function (r range: 0.374-0.554) (P 0.05). In conclusion, isometric, isokinetic, and isoinertial modalities ensure valid and reliable assessment of quadriceps muscle strength in TKA patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

Isokinetic Extension Strength Is Associated With Single-Leg Vertical Jump Height.

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Fischer, Felix; Blank, Cornelia; Dünnwald, Tobias; Gföller, Peter; Herbst, Elmar; Hoser, Christian; Fink, Christian

2017-11-01

Isokinetic strength testing is an important tool in the evaluation of the physical capacities of athletes as well as for decision making regarding return to sports after anterior cruciate ligament (ACL) reconstruction in both athletes and the lay population. However, isokinetic testing is time consuming and requires special testing equipment. A single-jump test, regardless of leg dominance, may provide information regarding knee extension strength through the use of correlation analysis of jump height and peak torque of isokinetic muscle strength. Cross-sectional study; Level of evidence, 3. A total of 169 patients who underwent ACL reconstruction were included in this study. Isokinetic testing was performed on the injured and noninjured legs. Additionally, a single-leg countermovement jump was performed to assess jump height using a jump accelerometer sensor. Extension strength values were used to assess the association between isokinetic muscle strength and jump height. The sample consisted of 60 female (mean age, 20.8 ± 8.3 years; mean weight, 61.7 ± 6.5 kg; mean height, 167.7 ± 5.3 cm) and 109 male (mean age, 23.2 ± 7.7 years; mean weight, 74.6 ± 10.2 kg; mean height, 179.9 ± 6.9 cm) patients. Bivariate correlation analysis showed an association ( r = 0.56, P jump height and isokinetic extension strength on the noninvolved side as well as an association ( r = 0.52, P jump height (beta = 0.49, P jump height having the strongest impact (beta = 0.49, P jump height. The study population encompassed various backgrounds, skill levels, and activity profiles, which might have affected the outcome. Even after controlling for age and sex, isokinetic strength was still moderately associated with jump height. Therefore, the jump technique and type of sport should be considered in future research.

Supervised dance intervention based on video game choreography increases quadriceps cross sectional area and peak of torque in community dwelling older women

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Elisângela Valevein Rodrigues

2018-06-01

Full Text Available Abstract AIMS the purpose of this study was to assess the effects of a supervised dance intervention based on video game choreography on isokinetic concentric and eccentric knee peak of torque (PT, quadriceps and hamstrings cross sectional area (CSA and functionality in community-dwelling older women. METHODS Forty-seven older women were allocated in Control Group (CG, n=25 and Intervention Group (IG, n=22. The IG performed dance based on video game choreography (Dance Central, XBOX 360®, Kinect, during 12 weeks, ~40 minutes, 3x/week, without foam (1-6week and with foam and visual disturbances (7-12 week. The pretest-training-posttest assessments included: isokinetic concentric and eccentric knee PT and CSA (Magnetic resonance imaging of quadriceps and hamstrings and functional tests. RESULTS The light-to-moderate-intensity 12-weeks training increased 8.5% the eccentric PT of quadriceps at 60°/s (p=0.04 and 1.3% quadriceps CSA (p=0.02. CONCLUSIONS These findings suggest that dance training based on video game choreography can enhance PT and induce hypertrophy in community-dwelling older women.

Effects of humeral head compression taping on the isokinetic strength of the shoulder external rotator muscle in patients with rotator cuff tendinitis.

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Kim, Moon-Hwan; Oh, Jae-Seop

2015-01-01

[Purpose] The purpose of this study was to examine the effects of humeral head compression taping (HHCT) on the strength of the shoulder external rotator muscle in patients with rotator cuff tendinitis. [Subjects and Methods] Twenty patients with rotator cuff tendinitis were recruited. The shoulder external rotator strength was measured using a Biodex isokinetic dynamometer system. A paired t-test was performed to evaluate within-group differences in the strength of the shoulder external rotator muscle. [Results] Significantly higher shoulder external rotator peak torque and peak torque per body weight were found in the HHCT condition than in the no-taping condition. [Conclusion] HHCT may effectively increase the shoulder external rotator muscle strength in patients with rotator cuff tendinitis.

Speed, not magnitude, of knee extensor torque production is associated with self-reported knee function early after anterior cruciate ligament reconstruction.

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Hsieh, Chao-Jung; Indelicato, Peter A; Moser, Michael W; Vandenborne, Krista; Chmielewski, Terese L

2015-11-01

To examine the magnitude and speed of knee extensor torque production at the initiation of advanced anterior cruciate ligament (ACL) reconstruction rehabilitation and the associations with self-reported knee function. Twenty-eight subjects who were 12 weeks post-ACL reconstruction and 28 age- and sex-matched physically active controls participated in this study. Knee extensor torque was assessed bilaterally with an isokinetic dynamometer at 60°/s. The variables of interest were peak torque, average rate of torque development, time to peak torque and quadriceps symmetry index. Knee function was assessed with the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). Peak torque and average rate of torque development were lower on the surgical side compared to the non-surgical side and controls. Quadriceps symmetry index was lower in subjects with ACL reconstruction compared to controls. On the surgical side, average rate of torque development was positively correlated with IKDC-SKF score (r = 0.379) while time to peak torque was negatively correlated with IKDC-SKF score (r = -0.407). At the initiation of advanced ACL reconstruction rehabilitation, the surgical side displayed deficits in peak torque and average rate of torque development. A higher rate of torque development and shorter time to peak torque were associated with better self-reported knee function. The results suggest that the rate of torque development should be addressed during advanced ACL reconstruction rehabilitation and faster knee extensor torque generation may lead to better knee function. III.

Relação entre a lesão condral e o pico de torque após reconstrução do ligamento cruzado anterior do joelho: estudo de casos Relationship between chondral lesion and peak torque following anterior cruciate ligament reconstruction of the knee: case study

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RF Traete

2007-06-01

Full Text Available CONTEXTUALIZAÇÃO: A associação entre lesão do ligamento cruzado anterior (LCA e desenvolvimento de osteoartrite (OA secundária tem sido objeto de vários estudos. A lesão ligamentar predispõe a lesões da cartilagem articular, influenciando, assim, o controle motor e o pico de torque. OBJETIVO: Avaliar a influência do grau de lesão condral no pico de torque da musculatura anterior e posterior da coxa após lesão e reconstrução do LCA. MÉTODO: Seis sujeitos do sexo masculino com lesão total e unilateral do LCA foram avaliados pré-cirurgia (24 horas antes da cirurgia e pós-cirurgia em dois momentos distintos, 4,66 ± 1,03 e 15,83 ± 2,63 meses, respectivamente. As avaliações isocinéticas foram realizadas no modo concêntrico de flexão e extensão do joelho, nas velocidades de 60º/s e 180º/s, em que foram a analisadas as variáveis PT dos isquiotibiais (PTI, PT do quadríceps (PTQ e a relação entre eles (I/Q. A escala histológica de Mankin modificada foi utilizada para avaliar o grau macroscópico de lesão condral. O teste estatístico ANOVA (pCONTEXT: The association between anterior cruciate ligament (ACL injury and the development of secondary osteoarthritis has been the subject of several studies. Ligament injury predisposes joint cartilage lesions, thus influencing motor control and peak torque. OBJECTIVE: To evaluate the influence of the degree of chondral lesion on peak torque of the anterior and posterior musculature of the thigh following ACL injury and reconstruction. METHOD: Six male subjects with total unilateral ACL injury were evaluated 24 hours before surgery and at two times after surgery (4.66 ± 1.03 and 15.83 ± 2.63 months, respectively. Isokinetic evaluations of knee flexion and extension were made in concentric mode, at velocities of 60º/s and 180º/s, and the variables of hamstring peak torque (HPT and quadriceps peak torque (QPT and hamstring/quadriceps ratio (H/Q were analyzed. The modified

Effect of isokinetic training on strength, functionality and proprioception in athletes with functional ankle instability.

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Sekir, Ufuk; Yildiz, Yavuz; Hazneci, Bulent; Ors, Fatih; Aydin, Taner

2007-05-01

The purpose of this study was to investigate the effects of isokinetic exercise on strength, joint position sense and functionality in recreational athletes with functional ankle instability (FAI). Strength, proprioception and balance of 24 recreational athletes with unilateral FAI were evaluated by using isokinetic muscle strength measurement, ankle joint position sense and one leg standing test. The functional ability was evaluated using five different tests. These were; single limb hopping course (SLHC), one legged and triple legged hop for distance (OLHD-TLHD), and six and cross six meter hop for time (SMHT-CSMHT). Isokinetic peak torque of the ankle invertor and evertor muscles were assessed eccentrically and concentrically at test speeds of 120 degrees /s. Isokinetic exercise protocol was carried out at an angular velocity of 120 degrees /s. The exercise session was repeated three times a week and lasted after 6 weeks. At baseline, concentric invertor strength was found to be significantly lower in the functionally unstable ankles compared to the opposite healthy ankles (p 0.05). Ankle joint position sense in the injured ankles declined significantly from 2.35 +/- 1.16 to 1.33 +/- 0.62 degrees for 10 degrees of inversion angle (p isokinetic exercise. One leg standing test score decreased significantly from 15.17 +/- 8.50 to 11.79 +/- 7.81 in the injured ankles (p isokinetic exercise protocol, all of the worsened functional test scores in the injured ankles as compared to the opposite healthy ankles displayed a significant improvement (p isokinetic exercise program used in this study had a positive effect on these parameters.

Absolute and relative reliability of isokinetic and isometric trunk strength testing using the IsoMed-2000 dynamometer.

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Roth, Ralf; Donath, Lars; Kurz, Eduard; Zahner, Lukas; Faude, Oliver

2017-03-01

The present study aimed to assess the between day reliability of isokinetic and isometric peak torque (PT) during trunk measurement on an isokinetic device (IsoMed 2000). Test-retest-protocol on five separate days. Fifteen healthy sport students (8 female and 7 male) aged 21 to 26. PT was assessed in isometric back extension and flexion as well as right and left rotation. Isokinetic strength was captured at a speed of 60°/s and 150°/s for all tasks. For none of the assessed parameters a meaningful variation in PT during test days was observed. Relative reliability (ICC = 0.85-0.96) was excellent for all tasks. Estimates of absolute reliability as Coefficient of Variation (CoV) and Standard Error of Measurement (SEM in Nm/kg lean body mass) remained stable for isometric (6.9% strength measurement in flexion and extension or trunk rotation in either isometric or isokinetic condition is highly reliable. Therefore, it seems possible to elucidate changes which are smaller than 10% due to intervention programs when a preceding familiarization condition was applied. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of the Competitive Season on the Isokinetic Muscle Parameters Changes in World-Class Handball Players.

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Maurelli, Olivier; Bernard, Pierre L; Dubois, Romain; Ahmaidi, Said; Prioux, Jacques

2018-05-25

Maurelli, O, Bernard, PL, Dubois, R, Ahmaidi, S, and Prioux, J. Effects of the competitive season on the isokinetic muscle parameters changes in world-class handball players. J Strength Cond Res XX(X): 000-000, 2018-The aim of this study is to investigate the effects of the competitive season on isokinetic muscular parameters of the lower limbs in world-class handball players. Nineteen, male, world-class, handball players (age, 26.6 ± 5.4 years) participated in the study. Two bilateral isokinetic tests of knee joint flexors (H; hamstring) and extensors (Q; quadriceps) were performed in the beginning and end of the competitive season to determine the peak torque (PT), the mean power, and agonist-antagonist ratio, dominant-nondominant ratio (DNDR), and combined ratio. The results showed a significant decrease in PT values at low angular velocity (60°·s) in concentric mode for Q on dominant leg (p handball players. Accordingly, this study should help trainers to modify their planning to maximize strength and power qualities of the lower limbs of their players in addition to avoiding injuries.

Isokinetic Evaluation of the Hip Flexor and Extensor Muscles: A Systematic Review.

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Zapparoli, Fabricio Yuri; Riberto, Marcelo

2017-11-01

Isokinetic dynamometry testing is a safe and reliable method accepted as the "gold standard" in the evaluation of muscle strength in the open kinetic chain. Isokinetic hip examinations face problems in the standardization of the position of the equipment axis, in the individual being examined, and in the adjustment of the lever arm and in stabilization strategies for the patients during the tests. Identification of the methodologic procedures with best reproducibility is also needed. To review the literature to evaluate the parameters used for the isokinetic evaluation of the hip flexor and extensor muscles and its reproducibility. This is a systematic literature review of the Cochrane, LILACS, PEDro, PubMed, and SciELO databases. The inclusion criteria were articles on the evaluation of hip flexor and/or extensor muscular strength with an isokinetic dynamometer and articles that analyzed the ICC or Pearson's reproducibility. The information extracted was positioning of the patient; positioning of the dynamometer axis; positioning of the lever arm; angular speed; sample size, pathology; type of contraction; and ICC and Pearson's results. 204 articles were found, from which 14 were selected that evaluated hip flexor and extensor muscles, involving 550 individuals who were submitted to an isokinetic hip evaluation. Five articles obtained the best result in reproducibility and had their methodology analyzed. To obtain better reproducibility of the isokinetic evaluation of the hip flexor and extensor muscles, the following recommendations must be followed: the individual must be positioned in the supine position and the dynamometer axis must be aligned with the greater trochanter of the femur. The positioning of the lever arm must be in the most distal region of the thigh possible. The angular speed used to analyze torque peak and muscle work was 60°/s, and to evaluate the muscle power it was 180°/s, with concentric and eccentric contractions being analyzed.

Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

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Natália Mariana Silva Luna

2012-09-01

Full Text Available OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and nonathletes. METHODS: Seventy-five males with a mean age of 30.26 (±6.5 years were divided into three groups: a triathlete group (n=26, a long-distance runner group (n = 23, and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. RESULTS: The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180º/s was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60º/s was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. CONCLUSIONS: The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners.

Influência do alongamento dos músculos isquiostibial e retofemoral no pico de torque e potência máxima do joelho Influence of stretching hamstring and quadriceps femoral muscles on knee peak torque and maximum power

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Gabriel Peixoto Leão Almeida

2009-12-01

the four-week study, as to knee range of motion (ROM flexion and extension, as well as to isokinetic dynamometry; variables analysed were knee ROM, peak torque and maximum power. Significant mean ROM differences were found between the three groups (p0.05. A and B groups showed increased ROM at the post-test, and only the C group showed significant increase in all isokinetic variables (p<0.05. Results then suggest that PNF stretching, performed with adequate duration and intensity, may be done before sports practice with no decrease in muscle strength.

Gender Differences in Isokinetic Strength after 60 and 90 d Bed Rest

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English, K. L.; Ploutz-Snyder, R. J.; Cromwell, R. L.; Ploutz-Snyder, L. L.

2010-01-01

Recent reports suggest that changes in muscle strength following disuse may differ between males and females. PURPOSE: To examine potential gender differences in strength changes following 60 and 90 d of experimental bed rest. METHODS: Isokinetic extensor and flexor strength of the knee (60deg and 180deg/s, concentric only), ankle (30deg/s, concentric and eccentric), and trunk (60deg/s, concentric only) were measured following 60 d (males: n=4, 34.5+/-9.6 y; females: n=4, 35.5+/-8.2 y) and 90 d (males: n=10, 31.4+/-4.8 y; females: n=5, 37.6+/-9.9 y) of 6-degree head-down-tilt bed rest (BR; N=23). Subjects were fed a controlled diet (55%/15%/ 30%, CHO/PRO/FAT) that maintained body weight within 3% of the weight recorded on Day 3 of bed rest. After a familiarization session, testing was conducted 6 d before BR and 2 d after BR completion. Peak torque and total work were calculated for the tests performed. To allow us to combine data from both 60- and 90-d subjects, we used a mixed-model statistical analysis in which time and gender were fixed effects and bed rest duration was a random effect. Log-transformations of strength measures were utilized when necessary in order to meet statistical assumptions. RESULTS: Main effects were seen for both time and gender (p<0.05), showing decreased strength in response to bed rest for both males and females, and males stronger than females for most strength measures. Only one interaction effect was observed: females exhibited a greater loss of trunk extensor peak torque at 60 d versus pre-BR, relative to males (p=0.004). CONCLUSION: Sixty and 90 d of BR induced significant losses in isokinetic muscle strength of the locomotor and postural muscles of the knee, ankle, and trunk. Although males were stronger than females for most of the strength measures that we examined, only changes in trunk extensor peak torque were greater for females than males at day 60 of bed rest

The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance

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Ratamess, Nicholas A.; Beller, Noah A.; Gonzalez, Adam M.; Spatz, Gregory E.; Hoffman, Jay R.; Ross, Ryan E.; Faigenbaum, Avery D.; Kang, Jie

2016-01-01

The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM) strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT) or a non-exercising control group (CTL). The IRT group underwent 6 weeks of training (2 days per week) consisting of 5 sets of 6-10 repetitions at 75-85% of subjects’ peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s-1 [3-sec concentric (CON) and 3-sec eccentric (ECC) phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey’s post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg), 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg), and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions) increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women. Key points Multiple-joint isokinetic resistance training increases dynamic maximal muscular strength, local muscular endurance, and maximal isokinetic strength in women. Multiple-joint isokinetic resistance training increased 1RM strength in the bench press

The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance.

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Ratamess, Nicholas A; Beller, Noah A; Gonzalez, Adam M; Spatz, Gregory E; Hoffman, Jay R; Ross, Ryan E; Faigenbaum, Avery D; Kang, Jie

2016-03-01

The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM) strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT) or a non-exercising control group (CTL). The IRT group underwent 6 weeks of training (2 days per week) consisting of 5 sets of 6-10 repetitions at 75-85% of subjects' peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s(-1) [3-sec concentric (CON) and 3-sec eccentric (ECC) phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey's post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg), 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg), and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions) increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women. Key pointsMultiple-joint isokinetic resistance training increases dynamic maximal muscular strength, local muscular endurance, and maximal isokinetic strength in women.Multiple-joint isokinetic resistance training increased 1RM strength in the bench press (by

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

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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.

ACUTE EFFECTS OF DIFFERENT STATIC STRETCHING PROTOCOLS ON PEAK TORQUE, CONVENTIONAL AND FUNCTIONAL HAMSTRINGS-TO-QUADRICEPS RATIOS IN ACTIVE WOMEN

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Ghada M. ALQaslah

2016-10-01

Full Text Available Background: This study might have been directed to some degree because of clashing results in the past studies regarding the impacts for different SS protocols on muscle strength and possibility for injury. The objective of the study was to investigate the acute effects of different static stretching (SS durations (20, 30, and 60s on isokinetic concentric quadriceps (Q and hamstrings (H peak torque (PT, eccentric H PT and conventional and functional H:Q ratios under different stretching conditions and angular velocities (60°and180°/s in active women. Methods: Isokinetic tests were performed on 108 active women. A HUMAC system was used to measure unilateral concentric Q and H PT, and eccentric H PT at 60 and 180º/s at baseline and after a bout of H-only, Q-only, and combined H and Q muscles SS. The data were statistically treated using five separate three-way (time x conditions x velocity ANOVA. Results: There were no significant differences among groups at baseline (P > 0.05. Significant reductions of all outcome measures have been shown to occur after 30 and 60s of SS (P 0.05. Conclusion: Short-lasting stretching can be done before exercises that require strength. However, since 30s or 60s stretching protocols adversely affect the muscle strength, performance and lower H:Q ratios they are not recommended prior to activities demanding the production of high forces.

The Effects of Multiple-Joint Isokinetic Resistance Training on Maximal Isokinetic and Dynamic Muscle Strength and Local Muscular Endurance

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Nicholas A. Ratamess, Noah A. Beller, Adam M. Gonzalez, Gregory E. Spatz, Jay R. Hoffman, Ryan E. Ross, Avery D. Faigenbaum, Jie Kang

2016-03-01

Full Text Available The transfer of training effects of multiple-joint isokinetic resistance training to dynamic exercise performance remain poorly understood. Thus, the purpose of the present study was to investigate the magnitude of isokinetic and dynamic one repetition-maximum (1RM strength and local muscular endurance increases after 6 weeks of multiple-joint isokinetic resistance training. Seventeen women were randomly assigned to either an isokinetic resistance training group (IRT or a non-exercising control group (CTL. The IRT group underwent 6 weeks of training (2 days per week consisting of 5 sets of 6-10 repetitions at 75-85% of subjects’ peak strength for the isokinetic chest press and seated row exercises at an average linear velocity of 0.15 m s-1 [3-sec concentric (CON and 3-sec eccentric (ECC phases]. Peak CON and ECC force during the chest press and row, 1RM bench press and bent-over row, and maximum number of modified push-ups were assessed pre and post training. A 2 x 2 analysis of variance with repeated measures and Tukey’s post hoc tests were used for data analysis. The results showed that 1RM bench press (from 38.6 ± 6.7 to 43.0 ± 5.9 kg, 1RM bent-over row (from 40.4 ± 7.7 to 45.5 ± 7.5 kg, and the maximal number of modified push-ups (from 39.5 ± 13.6 to 55.3 ± 13.1 repetitions increased significantly only in the IRT group. Peak isokinetic CON and ECC force in the chest press and row significantly increased in the IRT group. No differences were shown in the CTL group for any measure. These data indicate 6 weeks of multiple-joint isokinetic resistance training increases dynamic muscle strength and local muscular endurance performance in addition to specific isokinetic strength gains in women.

Degree of thoracic kyphosis and peak torque of trunk flexors and extensors among healthy women.

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Granito, Renata Neves; Aveiro, Mariana Chaves; Rennó, Ana Claudia Muniz; Oishi, Jorge; Driusso, Patricia

2014-01-01

The aim of this study was to analyze the effects of aging on the degree of thoracic kyphosis and peak torque of the trunk flexor and extensor muscles among women without a densitometric diagnosis of osteoporosis. Thirty women were selected to make up three groups: young women (n = 10; 24.60 ± 2.27 years of age); adults (n = 10; 43.50 ± 2.88); and elderly women (n = 10; 62.40 ± 2.67). Bone mineral density (BMD), degree of thoracic kyphosis and peak torque of the trunk flexors and extensors were evaluated. Differences between the groups were evaluated using the Kruskal-Wallis ANOVA and Mann-Whitney U tests. Pearson's correlation coefficient was used to assess correlations between the variables. The significance level was taken to be 5% (p ≤ 0.05). The elderly group presented a greater degree of thoracic kyphosis (p = 0.009) and lower peak torque of the trunk flexors and extensors than the young group. The adult group presented lower peak torque of the trunk than the young group. A negative correlation was observed between age and peak torque of the trunk flexors and extensors (p ≤ 0.001), and a positive correlation between age and the degree of thoracic kyphosis (r = 0.58; p ≤ 0.001). The elderly group presented higher values for the eccentric/concentric ratio of the peak torque for flexors (p = 0.03) and extensors (p = 0.02). This study suggests that physiological aging may be associated with a greater degree of thoracic kyphosis and lower muscle strength of the trunk flexors and extensors. Moreover, the elderly women showed a relative capacity for preservation of eccentric strength.

Degree of thoracic kyphosis and peak torque of trunk flexors and extensors among healthy women,

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Renata Neves Granito

2014-06-01

Full Text Available OBJECTIVE: The aim of this study was to analyze the effects of aging on the degree of thoracic kyphosis and peak torque of the trunk flexor and extensor muscles among women without a densitometric diagnosis of osteoporosis.METHODS: Thirty women were selected to make up three groups: young women (n = 10; 24.60 ± 2.27 years of age; adults (n = 10; 43.50 ± 2.88; and elderly women (n= 10; 62.40 ± 2.67. Bone mineral density (BMD, degree of thoracic kyphosis and peak torque of the trunk flexors and extensors were evaluated. Differences between the groups were evaluated using the Kruskal-Wallis ANOVA and Mann-Whitney U tests. Pearson's correlation coefficient was used to assess correlations between the variables. The significance level was taken to be 5% (p < 0.05.RESULTS: The elderly group presented a greater degree of thoracic kyphosis (p = 0.009 and lower peak torque of the trunk flexors and extensors than the young group. The adult group presented lower peak torque of the trunk than the young group. A negative correlation was observed between age and peak torque of the trunk flexors and extensors (p < 0.001, and a positive correlation between age and the degree of thoracic kyphosis (r = 0.58; p < 0.001. The elderly group presented higher values for the eccentric/concentric ratio of the peak torque for flexors (p = 0.03 and extensors (p = 0.02.CONCLUSION: This study suggests that physiological aging may be associated with a greater degree of thoracic kyphosis and lower muscle strength of the trunk flexors and extensors. Moreover, the elderly women showed a relative capacity for preservation of eccentric strength.

THE EFFICACY OF ANGLE-MATCHED ISOKINETIC KNEE FLEXOR AND EXTENSOR STRENGTH PARAMETERS IN PREDICTING AGILITY TEST PERFORMANCE.

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Greig, Matt; Naylor, James

2017-10-01

Agility is a fundamental performance element in many sports, but poses a high risk of injury. Hierarchical modelling has shown that eccentric hamstring strength is the primary determinant of agility performance. The purpose of this study was to investigate the relationship between knee flexor and extensor strength parameters and a battery of agility tests. Controlled laboratory study. Nineteen recreational intermittent games players completed an agility battery and isokinetic testing of the eccentric knee flexors (eccH) and concentric knee extensors (conQ) at 60, 180 and 300°·s -1 . Peak torque and the angle at which peak torque occurred were calculated for eccH and conQ at each speed. Dynamic control ratios (eccH:conQ) and fast:slow ratios (300:60) were calculated using peak torque values, and again using angle-matched data, for eccH and conQ. The agility test battery differentiated linear vs directional changes and prescriptive vs reactive tasks. Linear regression showed that eccH parameters were generally a better predictor of agility performance than conQ parameters. Stepwise regression showed that only angle-matched strength ratios contributed to the prediction of each agility test. Trdaitionally calculated strength ratios using peak torque values failed to predict performance. Angle-matched strength parameters were able to account for 80% of the variation in T-test performance, 70% of deceleration distance, 55% of 10m sprint performance, and 44% of reactive change of direction speed. Traditionally calculated strength ratios failed to predict agility performance, whereas angle-matched strength ratios had better predictive ability and featured in a predictive stepwise model for each agility task. 2c.

Isokinetic profile of elbow flexion and extension strength in elite junior tennis players.

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Ellenbecker, Todd S; Roetert, E Paul

2003-02-01

Descriptive study. To determine whether bilateral differences exist in concentric elbow flexion and extension strength in elite junior tennis players. The repetitive nature of tennis frequently produces upper extremity overuse injuries. Prior research has identified tennis-specific strength adaptation in the dominant shoulder and distal upper extremity musculature of elite players. No previous study has addressed elbow flexion and extension strength. Thirty-eight elite junior tennis players were bilaterally tested for concentric elbow flexion and extension muscle performance on a Cybex 6000 isokinetic dynamometer at 90 degrees/s, 210 degrees/s, and 300 degrees/s. Repeated-measures ANOVAs were used to test for differences between extremities, muscle groups, and speed. Significantly greater (Pelbow extension peak torque values were measured at 90 degrees/s, 210 degrees/s, and 300 degrees/s for males. Significantly greater (Pelbow flexion muscular performance in males and for elbow flexion or extension peak torque and single-repetition work values in females. No significant difference between extremities was measured in elbow flexion/extension strength ratios in females and significant differences between extremities in this ratio were only present at 210 degrees/s in males (Pelbow in male elite junior tennis players but not females. These data have ramifications for clinicians rehabilitating upper extremity injuries in patients from this population.

Isokinetic and isometric strength in osteoarthrosis of the knee. A comparative study with healthy women.

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Tan, J; Balci, N; Sepici, V; Gener, F A

1995-01-01

Dynamic stability of the knee joint depends on the appropriate strength ratio of quadriceps and hamstring muscles. The purpose of this investigation was to determine the maximum peak torque (MPT) and MPT ratios of hamstrings to quadriceps (H/Q) muscles in patients with knee osteoarthritis (OA). Two groups of patients were included in the study. The first group consisted of 30 patients (Group A) with the clinical and radiologic findings of knee OA. The second group consisted of 30 patients (Group B) exhibiting knee joint pain without roentgenologic findings of knee OA. The findings of two patient groups were compared with each other and also with 30 healthy subjects (Group C). Isokinetic (at 60 degrees/s and at 180 degrees/s) and isometric (at 30 degrees and at 60 degrees of knee flexion) tests were performed by the rate-limiting isokinetic dynamometer system. Isokinetic and isometric MPT loss of knee flexors and extensors was found in both patient groups with respect to controls, but MPT ratios of H/Q muscles did not show a statistically significant difference compared with the control group. This may be related to the equal strength loss of knee flexors and knee extensors in patients with knee OA. It is concluded that strengthening exercises of hamstring muscles is as important as quadriceps strengthening in rehabilitation of knee OA.

Degree of thoracic kyphosis and peak torque of trunk flexors and extensors among healthy women☆☆☆

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Granito, Renata Neves; Aveiro, Mariana Chaves; Rennó, Ana Claudia Muniz; Oishi, Jorge; Driusso, Patricia

2014-01-01

Objective The aim of this study was to analyze the effects of aging on the degree of thoracic kyphosis and peak torque of the trunk flexor and extensor muscles among women without a densitometric diagnosis of osteoporosis. Methods Thirty women were selected to make up three groups: young women (n = 10; 24.60 ± 2.27 years of age); adults (n = 10; 43.50 ± 2.88); and elderly women (n = 10; 62.40 ± 2.67). Bone mineral density (BMD), degree of thoracic kyphosis and peak torque of the trunk flexors and extensors were evaluated. Differences between the groups were evaluated using the Kruskal–Wallis ANOVA and Mann–Whitney U tests. Pearson's correlation coefficient was used to assess correlations between the variables. The significance level was taken to be 5% (p ≤ 0.05). Results The elderly group presented a greater degree of thoracic kyphosis (p = 0.009) and lower peak torque of the trunk flexors and extensors than the young group. The adult group presented lower peak torque of the trunk than the young group. A negative correlation was observed between age and peak torque of the trunk flexors and extensors (p ≤ 0.001), and a positive correlation between age and the degree of thoracic kyphosis (r = 0.58; p ≤ 0.001). The elderly group presented higher values for the eccentric/concentric ratio of the peak torque for flexors (p = 0.03) and extensors (p = 0.02). Conclusion This study suggests that physiological aging may be associated with a greater degree of thoracic kyphosis and lower muscle strength of the trunk flexors and extensors. Moreover, the elderly women showed a relative capacity for preservation of eccentric strength. PMID:26229814

Comparison of different passive knee extension torque-angle assessments

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Freitas, Sandro R; Vaz, João R; Bruno, Paula M; Valamatos, Maria J; Mil-Homens, Pedro

2013-01-01

Previous studies have used isokinetic dynamometry to assess joint torques and angles during passive extension of the knee, often without reporting upon methodological errors and reliability outcomes. In addition, the reliability of the techniques used to measure passive knee extension torque-angle and the extent to which reliability may be affected by the position of the subjects is also unclear. Therefore, we conducted an analysis of the intra- and inter-session reliability of two methods of assessing passive knee extension: (A) a 2D kinematic analysis coupled to a custom-made device that enabled the direct measurement of resistance to stretch and (B) an isokinetic dynamometer used in two testing positions (with the non-tested thigh either flexed at 45° or in the neutral position). The intra-class correlation coefficients (ICCs) of torque, the slope of the torque-angle curve, and the parameters of the mathematical model that were fit to the torque-angle data for the above conditions were measured in sixteen healthy male subjects (age: 21.4 ± 2.1 yr; BMI: 22.6 ± 3.3 kg m −2 ; tibial length: 37.4 ± 3.4 cm). The results found were: (1) methods A and B led to distinctly different torque-angle responses; (2) passive torque-angle relationship and stretch tolerance were influenced by the position of the non-tested thigh; and (3) ICCs obtained for torque were higher than for the slope and for the mathematical parameters that were fit to the torque-angle curve. In conclusion, the measurement method that is used and the positioning of subjects can influence the passive knee extension torque-angle outcome. (paper)

Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

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Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

2016-04-01

We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.

Profile of isokinetic eccentric-to-concentric strength ratios of shoulder rotator muscles in elite female team handball players.

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Andrade, Marilia Dos Santos; Fleury, Anna Maria; de Lira, Claudio Andre Barbosia; Dubas, Joao Paulo; da Silva, Antonio Carlos

2010-05-01

The purpose of this study was to establish the isokinetic profile of shoulder rotator muscles strength in female handball players. Twenty-seven handball players performed concentric and eccentric strength tests of both dominant and non-dominant upper limbs on an isokinetic dynamometer. Internal and external rotator muscles peak torque was assessed at 1.05, 3.14, and 5.23 rad . s(-1) in concentric mode and at 3.14 and 5.23 rad . s(-1) in eccentric mode. Concentric balance ratio and functional ratio were obtained. Bi-lateral deficiency was compared. Concentric strength for internal and external rotation was significantly greater for the dominant than for the non-dominant limb for all speeds (P muscles were stronger in the dominant than the non-dominant limb (P stronger than the non-dominant side, balance concentric ratios remained the same, with only the functional strength ratio different at 5.23 rad . s(-1). Our results suggest that concentric strength exercises be used for internal and external rotators on the non-dominant side, and functional exercise that improves eccentric rotation strength for prevention programmes.

Provocative mechanical tests of the peripheral nervous system affect the joint torque-angle during passive knee motion.

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Andrade, R J; Freitas, S R; Vaz, J R; Bruno, P M; Pezarat-Correia, P

2015-06-01

This study aimed to determine the influence of the head, upper trunk, and foot position on the passive knee extension (PKE) torque-angle response. PKE tests were performed in 10 healthy subjects using an isokinetic dynamometer at 2°/s. Subjects lay in the supine position with their hips flexed to 90°. The knee angle, passive torque, surface electromyography (EMG) of the semitendinosus and quadriceps vastus medialis, and stretch discomfort were recorded in six body positions during PKE. The different maximal active positions of the cervical spine (neutral; flexion; extension), thoracic spine (neutral; flexion), and ankle (neutral; dorsiflexion) were passively combined for the tests. Visual analog scale scores and EMG were unaffected by body segment positioning. An effect of the ankle joint was verified on the peak torque and knee maximum angle when the ankle was in the dorsiflexion position (P torque (P torque when the cervical and thoracic spines were flexed (P torque-angle response since different positions of head, upper trunk, and foot induce dissimilar knee mechanical responses during passive extension. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A Comparison of Isokinetic Knee Strength and Power Output Ratios Between Female Basketball and Volleyball Players

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Kabaciński Jarosław

2017-09-01

Full Text Available Purpose. Tests such as the counter movement jump (CMJ and squat jump (SJ allow for determining the ratio of maximal power output generated during SJ to CMJ (S/C. The isokinetic peak torque ratio of the hamstrings contracting eccentrically to the quadriceps contracting concentrically (H/Q is defined as functional H/Q. The purpose of this study was to compare the S/C and functional H/Q between female basketball and volleyball players. Methods. The total of 14 female basketball players (age, 19.8 ± 1.4 years and 12 female volleyball players (age, 22.3 ± 4.2 years participated in the study. A piezoelectric force platform was used for the CMJ and SJ. Moreover, isokinetic tests of the hamstrings and quadriceps muscle torque during eccentric and concentric contraction were performed. Results. The results of the S/C and functional H/Q at 90 deg · s-1/60 deg · s-1 velocities were higher in basketball players (87.3 ± 9.1% and 91.4 ± 9.3%, respectively than in volleyball players (83.1 ± 9.8% and 83.6 ± 16.5%, respectively. No significant differences in S/C or functional H/Q values between the two groups were found (p > 0.05. Conclusions. Decreasing the S/C may result from an improvement in the power output during CMJ and a better utilization of the stretch-shortening cycle effect. Balancing the functional H/Q through increasing the eccentric hamstrings strength can provide dynamic knee joint stabilization.

Test-Retest Reliability of Isokinetic Knee Strength Measurements in Children Aged 8 to 10 Years.

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Fagher, Kristina; Fritzson, Annelie; Drake, Anna Maria

Isokinetic dynamometry is a useful tool to objectively assess muscle strength of children and adults in athletic and rehabilitative settings. This study examined test-retest reliability of isokinetic knee strength measurements in children aged 8 to 10 years and defined limits for the minimum difference (MD) in strength that indicates a clinically important change. Isokinetic knee strength measurements (using the Biodex System 4) in children will provide reliable results. Descriptive laboratory study. In 22 healthy children, 5 maximal concentric (CON) knee extensor (KE) and knee flexor (KF) contractions at 2 angular velocities (60 deg/s and 180 deg/s) and 5 maximal eccentric (ECC) KE/KF contractions at 60 deg/s were assessed 7 days apart. The intraclass correlation coefficient (ICC 2.1 ) was used to examine relative reliability, and the MD was calculated on the basis of standard error of measurement. ICCs for CON KE/KF peak torque measurements were fair to excellent (range, 0.49-0.81). The MD% values for CON KE and KF ranged from 31% to 37% at 60 deg/s and from 34% to 39% at 180 deg/s. ICCs in the ECC mode were good (range, 0.60-0.70), but associated MD% values were high (>50%). There was no systematic error for CON KE/KF and ECC KE strength measurements at 60 deg/s, but systematic error was found for all other measurements. The dynamometer provides a reliable analysis of isokinetic CON knee strength measurements at 60 deg/s in children aged 8 to 10 years. Measurements at 180 deg/s and in the ECC mode were not reliable, indicating a need for more familiarization prior to testing. The MD values may help clinicians to determine whether a change in knee strength is due to error or intervention.

Peak torque and muscle balance in the knees of young U-15 and U-17 soccer athletes playing various tactical positions.

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Chiamonti Bona, Cleiton; Tourinho Filho, Hugo; Izquierdo, Mikel; Pires Ferraz, Ricardo M; Marques, Mário C

2017-01-01

Soccer is a sport that is practiced worldwide and has been investigated in its various aspects, particularly muscle strength, which is an essential motor skill for sports performance. The objective of this study was to investigate the peak torque and muscle balance on the knee extensor and flexor of young soccer players in the tactical positions of goalkeeper, defender, full back, midfielder, defensive midfielder and striker, as well as to determine which field position has the highest peak torque. Forty-nine male players were recruited and divided into two categories during the preparatory period of the season: the Under-15 (U-15) group (N.=23, mean age 14.7±0.5 years, body mass 58.2±10.5 kg, body height 168.5±7.6 cm), and the Under-17 (U-17) group (N.=26, mean age 16.8±0.4 years, body mass 69.2±7.9 kg, body height 176.2±6.6 cm). The U-17 athletes presented a higher peak torque in all the movements of flexion and extension in the two angular velocities (i.e. 60°/s and 300°/s), but only the dominant knee extensor at 300°/s was significantly different between the two categories as well as the percentage change in peak torque compared between U-15 and U-17 was always above 20%. The peak torque variation in the U-17 category (i.e. mostly above 20%) highlights a higher peak torque compared to U-15 athletes. The muscular deficit of the two categories presented a low average of 10-15%, indicating a good muscle balance between knee extensors and flexors. Finally, goalkeepers and defenders achieved the highest peak torque amongst the field positions.

Internal- and External-Rotation Peak Toque in Little League Baseball Players With Subacromial Impingement Syndrome: Improved by Closed Kinetic Chain Shoulder Training.

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Lee, Dong-Rour; Kim, Laurentius Jongsoon

2016-08-01

Many studies have explored closed kinetic chain (CKC) shoulder exercises (SEs) with a sling because they are safer and more effective than open-chain exercises, especially in early stages of treatment. However, the application of CKC SE in youth baseball players has rarely been attempted, although teenage baseball players also experience shoulder pain. To investigate the effects of CKC SE on the peak torque of shoulder internal rotation (IR) and external rotation (ER) in youth baseball players. Single-group pretest, posttest. Biomechanics laboratory. 23 Little League Baseball players with subacromial impingement syndrome. The CKC SE with a sling was CKC shoulder-flexion exercise, extension exercise, IR exercise, and ER exercise. This exercise regimen was conducted 2 or 3 times/wk for 8 wk. The peak torque of shoulder IR and ER was measured using an isokinetic dynamometer. Concentric shoulder rotation was performed, with 5 repetitions at an angular velocity of 60°/s and 15 at 180°/s. The IR and ER peak torque significantly increased at each angular velocity after the exercise program. In particular, the increase in IR and ER peak torque values was statistically significant at an angular velocity of 180°/s. CKC SE was effective in increasing shoulder IR and ER strength, demonstrating its potential benefits in the prevention and treatment of shoulder injury. In addition, increased IR peak torque appears to improve throwing velocity in baseball players.

The effect of isokinetic and proprioception training on strength, movement and gait parameters after acute supination injury of the ankle ligaments

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C. Mucha

2009-01-01

Full Text Available The effects of a three-week isokinetic training compared to typical proprio -ceptive training on parameters of strength, movement and gait function after acute ankle ligament sprain were investigated. Thirty-nine patients were randomly allocated to two comparison groups. In group 1 (n=20a proprioceptive training and in group 2 (n=19 an isokinetic strength training (Cybex 6000® were administered. Thepatients of both groups underwent training five times a week for three weeks. Before and at the end of the treatmentcourse, in both groups isokinetic strength was tested, the range of motion in the ankle joint was recorded and gait wasanalyzed (multicomponent strength measurement platform, Henschel-System®. The maximum isokinetic torque(60°/s [Nm] and the contact time (monopedal support time of the injured leg during gait cycle were the basis for evaluation.The data obtained show that in group 2 a significantly greater increase of the maximum isokinetic torque wasattained in almost all range of motion of the ankle joint in the course of treatment. A t the same time, in group 2 theshortening of the contact time in the stance phase of the injured leg could be compensated. The active range of motionin the ankle joint was less at the end of treatment in group 2 than in group 1. The isokinetic training obviously did notonly lead to better strength regeneration, but also to a functionally more stable ankle joint with a rhythmically moreevenly balanced stance phase of the gait cycle.  These results suggest that the used isokinetic training had positive effects on functional stability after acute ankle sprain.

Muscle recruitment patterns of the subscapularis, serratus anterior and other shoulder girdle muscles during isokinetic internal and external rotations.

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Gaudet, Sylvain; Tremblay, Jonathan; Begon, Mickael

2018-05-01

The aims of this study were to investigate the differences in peak muscle activity and recruitment patterns during high- and low-velocity, concentric and eccentric, internal and external isokinetic shoulder rotations. Electromyographic activity of the rotator cuff and eight superficial muscles of the shoulder girdle was recorded on 25 healthy adults during isokinetic internal and external shoulder rotation at 60°/s and 240°/s. Peak muscle activity, electromyographic envelopes and peak isokinetic moments were analyzed using three-factor ANOVA and statistical parametric mapping. The subscapularis and serratus anterior showed moderate to high peak activity levels during each conditions, while the middle and posterior deltoids, upper, middle and lower trapezius, infraspinatus and supraspinatus showed higher peak activity levels during external rotations (+36.5% of maximum voluntary activation (MVA)). The pectoralis major and latissimus dorsi were more active during internal rotations (+40% of MVA). Only middle trapezius and pectoralis major electromyographic activity decreased with increasing velocity. Peak muscle activity was similar or lower during eccentric contractions, although the peak isokinetic moment increased by 35% on average. The subscapularis and serratus anterior appear to be important stabilizers of the glenohumeral joint and scapula. Isokinetic eccentric training at high velocities may allow for faster recruitment of the shoulder girdle muscles, which could improve joint stability during shoulder internal and external rotations.

ANALYSIS OF ISOKINETIC KNEE EXTENSION / FLEXION IN MALE ELITE ADOLESCENT WRESTLERS

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Sanli Sadi Kurdak

2005-12-01

Full Text Available Wrestling requires strength of the upper and lower body musculature which is critical for the athletic performance. Evaluation of the adolescent's skeletal muscle is important to understand body movement, especially including those involved in sports. Strength, power and endurance capacity are defined as parameters of skeletal muscle biomechanical properties. The isokinetic dynamometer is an important toll for making this type of evaluation. However, load range phase of range of motion has to be considered to interpret the data correctly. With this in mind we aimed to investigate the lover body musculature contractile characteristics of adolescent wrestlers together with detailed analyses of load range phase of motion. Thirteen boys aged 12 - 14 years participated to this study. Concentric load range torque, work and power of knee extension and flexion were measured by a Cybex Norm dynamometer at angular velocities from 450°/sec to 30°/sec with 30°/sec decrements for each set. None of the wrestlers were able to attain load range for angular velocities above 390°/sec and 420°/sec for extension and flexion respectively. Detailed analyses of the load range resulted in statistically significant differences in the normalized load range peak torque for extension at 270°/sec (1.44 ± 0.28 Nm·kg-1 and 1.14 ± 0.28 Nm·kg-1 for total and load range peak torque respectively, p < 0.05, and for flexion at 300°/sec (1.26 ± 0.28 Nm·kg-1 and 1.03 ± 0.23 Nm·kg-1 for total and load range peak torque respectively, p < 0.05, compared to total peak torque data. Similarly, the significant difference was found for the work values at 90°/sec (1.91 ± 0.23 Nm·kg-1 and 1.59 ± 0.24 Nm·kg-1 for total and load range work respectively for extension and 1.73 ± 0.21 Nm·kg-1 and 1.49 ± 0.19 Nm·kg-1 for total and load range work respectively for flexion, p < 0.05, and was evident at higher angular velocities (p < 0.001 for both extension and flexion. At

Isokinetic knee strength qualities as predictors of jumping performance in high-level volleyball athletes: multiple regression approach.

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Sattler, Tine; Sekulic, Damir; Spasic, Miodrag; Osmankac, Nedzad; Vicente João, Paulo; Dervisevic, Edvin; Hadzic, Vedran

2016-01-01

Previous investigations noted potential importance of isokinetic strength in rapid muscular performances, such as jumping. This study aimed to identify the influence of isokinetic-knee-strength on specific jumping performance in volleyball. The secondary aim of the study was to evaluate reliability and validity of the two volleyball-specific jumping tests. The sample comprised 67 female (21.96±3.79 years; 68.26±8.52 kg; 174.43±6.85 cm) and 99 male (23.62±5.27 years; 84.83±10.37 kg; 189.01±7.21 cm) high- volleyball players who competed in 1st and 2nd National Division. Subjects were randomly divided into validation (N.=55 and 33 for males and females, respectively) and cross-validation subsamples (N.=54 and 34 for males and females, respectively). Set of predictors included isokinetic tests, to evaluate the eccentric and concentric strength capacities of the knee extensors, and flexors for dominant and non-dominant leg. The main outcome measure for the isokinetic testing was peak torque (PT) which was later normalized for body mass and expressed as PT/Kg. Block-jump and spike-jump performances were measured over three trials, and observed as criteria. Forward stepwise multiple regressions were calculated for validation subsamples and then cross-validated. Cross validation included correlations between and t-test differences between observed and predicted scores; and Bland Altman graphics. Jumping tests were found to be reliable (spike jump: ICC of 0.79 and 0.86; block-jump: ICC of 0.86 and 0.90; for males and females, respectively), and their validity was confirmed by significant t-test differences between 1st vs. 2nd division players. Isokinetic variables were found to be significant predictors of jumping performance in females, but not among males. In females, the isokinetic-knee measures were shown to be stronger and more valid predictors of the block-jump (42% and 64% of the explained variance for validation and cross-validation subsample, respectively

Determination of concentric and eccentric peak moment values for trunk flexion and extension in sedentary asymptomatic individuals by isokinetic dynamometry: a pilot study

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Rafaella Stradiotto Bernardelli

2017-11-01

Full Text Available The spine has a direct influence on postural alignment and movement of the whole body. Lumbar muscles constitute a critical element in trunk performance while weakness of these muscles has been associated with low back pain. Hence, strength profiling of trunk muscles is clinically significant. The objective of this research was to determine, by means of isokinetic dynamometry, peak moment (PM values during isokinetic concentric and eccentric efforts of trunk flexion and extension in sedentary asymptomatic individuals. The sample consisted of 100 asymptomatic sedentary volunteers, fifty from each sex, aging 22.2 ± 3.3 years old. The sample underwent concentric and eccentric isokinetic assessment of the trunk flexor and extensor muscles at an angular velocity of 60 degrees/sec for each mode of contraction. The mean concentric PM for trunk flexion and extension were 139.5 and 166.6 Nm, respectively, while the respective values for the eccentric efforts were 188.8 and 221.2 Nm. The PM flexion/extension ratio was 0.87 and 0.89 for the concentric and eccentric efforts, respectively. These values of concentric and eccentric PM and PM ratio will serve as comparison parameters for future research, as well as for the assessment of symptomatic patients, and to help in the creation of the trunk muscle rebalance protocols.

Isokinetic dynamometry of knee flexors and extensors: comparative study among non-athletes, jumper athletes and runner athletes

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Siqueira Cássio Marinho

2002-01-01

Full Text Available Participation in intensive sports activities leads to muscular specializations that may generate alterations in involved articular forces and cause static (posture and dynamic changes (alterations of articular stability, coordination, etc.. Prevention of injury requires specific functional muscular evaluation in all athletes and for any kind of sport. OBJECTIVE: To dynamically evaluate, through isokinetic tests, the peak torque, total work, and average power of the knee flexor and extensor muscles of jumper and runner athletes and compare them to those of a non-athletic population, evaluating dominance and balance between agonistic and antagonistic muscle groups. RESULTS: In the non-athlete group, we noted a higher asymmetry between the dominant and nondominant members. The jumpers had the highest values of the evaluated parameters of all groups, whereas parameters for the runners were intermediate between non-athletes and jumpers.

3D strength surfaces for ankle plantar- and dorsi-flexion in healthy adults: an isometric and isokinetic dynamometry study

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Sara J. Hussain

2016-11-01

Full Text Available Abstract Background The ankle is an important component of the human kinetic chain, and deficits in ankle strength can negatively impact functional tasks such as balance and gait. While peak torque is influenced by joint angle and movement velocity, ankle strength is typically reported for a single angle or movement speed. To better identify deficits and track recovery of ankle strength after injury or surgical intervention, ankle strength across a range of movement velocities and joint angles in healthy adults is needed. Thus, the primary goals of this study were to generate a database of strength values and 3-dimensional strength surface models for plantarflexion (PF and dorsiflexion (DF ankle strength in healthy men and women. Secondary goals were to develop a means to estimate ankle strength percentiles as well as examine predictors of maximal ankle strength in healthy adults. Methods Using an isokinetic dynamometer, we tested PF and DF peak torques at five joint angles (−10° [DF], 0° [neutral], 10° [PF], 20° [PF] and 30° [PF] and six velocities (0°/s, 30°/s, 60°/s, 90°/s, 120°/s and 180°/s in 53 healthy adults. These data were used to generate 3D plots, or “strength surfaces”, for males and females for each direction; surfaces were fit using a logistic equation. We also tested predictors of ankle strength, including height, weight, sex, and self-reported physical activity levels. Results Torque-velocity and torque-angle relationships at the ankle interact, indicating that these relationships are interdependent and best modeled using 3D surfaces. Sex was the strongest predictor of ankle strength over height, weight, and self-reported physical activity levels. 79 to 97 % of the variance in mean peak torque was explained by joint angle and movement velocity using logistic equations, for men and women and PF and DF directions separately. Conclusions The 3D strength data and surface models provide a more comprehensive dataset

3D strength surfaces for ankle plantar- and dorsi-flexion in healthy adults: an isometric and isokinetic dynamometry study.

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Hussain, Sara J; Frey-Law, Laura

2016-01-01

The ankle is an important component of the human kinetic chain, and deficits in ankle strength can negatively impact functional tasks such as balance and gait. While peak torque is influenced by joint angle and movement velocity, ankle strength is typically reported for a single angle or movement speed. To better identify deficits and track recovery of ankle strength after injury or surgical intervention, ankle strength across a range of movement velocities and joint angles in healthy adults is needed. Thus, the primary goals of this study were to generate a database of strength values and 3-dimensional strength surface models for plantarflexion (PF) and dorsiflexion (DF) ankle strength in healthy men and women. Secondary goals were to develop a means to estimate ankle strength percentiles as well as examine predictors of maximal ankle strength in healthy adults. Using an isokinetic dynamometer, we tested PF and DF peak torques at five joint angles (-10° [DF], 0° [neutral], 10° [PF], 20° [PF] and 30° [PF]) and six velocities (0°/s, 30°/s, 60°/s, 90°/s, 120°/s and 180°/s) in 53 healthy adults. These data were used to generate 3D plots, or "strength surfaces", for males and females for each direction; surfaces were fit using a logistic equation. We also tested predictors of ankle strength, including height, weight, sex, and self-reported physical activity levels. Torque-velocity and torque-angle relationships at the ankle interact, indicating that these relationships are interdependent and best modeled using 3D surfaces. Sex was the strongest predictor of ankle strength over height, weight, and self-reported physical activity levels. 79 to 97 % of the variance in mean peak torque was explained by joint angle and movement velocity using logistic equations, for men and women and PF and DF directions separately. The 3D strength data and surface models provide a more comprehensive dataset of ankle strength in healthy adults than previously reported. These

Kilohertz and Low-Frequency Electrical Stimulation With the Same Pulse Duration Have Similar Efficiency for Inducing Isometric Knee Extension Torque and Discomfort.

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Medeiros, Flávia Vanessa; Bottaro, Martim; Vieira, Amilton; Lucas, Tiago Pires; Modesto, Karenina Arrais; Bo, Antonio Padilha L; Cipriano, Gerson; Babault, Nicolas; Durigan, João Luiz Quagliotti

2017-06-01

To test the hypotheses that, as compared with pulsed current with the same pulse duration, kilohertz frequency alternating current would not differ in terms of evoked-torque production and perceived discomfort, and as a result, it would show the same current efficiency. A repeated-measures design with 4 stimuli presented in random order was used to test 25 women: (1) 500-microsecond pulse duration, (2) 250-microsecond pulse duration, (3) 500-microsecond pulse duration and low carrier frequency (1 kHz), (4) 250-microsecond pulse duration and high carrier frequency (4 kHz). Isometric peak torque of quadriceps muscle was measured using an isokinetic dynamometer. Discomfort was measured using a visual analog scale. Currents with long pulse durations induced approximately 21% higher evoked torque than short pulse durations. In addition, currents with 500 microseconds delivered greater amounts of charge than stimulation patterns using 250-microsecond pulse durations (P torque and discomfort. However, neuromuscular electrical stimulation (NMES) with longer pulse duration induces higher NMES-evoked torque, regardless of the carrier frequency. Pulse duration is an important variable that should receive more attention for an optimal application of NMES in clinical settings.

Análise isocinética da articulação do cotovelo em crianças com paralisia cerebral Isokinetic analysis of the elbow joint in children with cerebral palsy

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Patrícia Martins Franciulli

2012-03-01

Full Text Available A quantidade de torque aplicado na articulação é uma medida de aptidão física importante para crianças com paralisia cerebral. O presente estudo analisou parâmetros cinéticos na articulação do cotovelo em crianças saudáveis e com paralisia cerebral. Participaram 10 crianças com paralisia cerebral e 10 crianças sem comprometimento neurológico. Avaliou-se a média do pico de torque, média do ângulo do pico de torque, coeficiente de variação do torque e aceleração angular do movimento de flexo-extensão do cotovelo nas velocidades com um dinamômetro isocinético. A média de pico de torque (extensão, aceleração (flexão e coeficiente de variação (flexão e extensão são diferentes entre grupos. Conclui-se que o torque e aceleração sofreram interferências no movimento de flexo-extensão; as principais diferenças encontradas foram entre os extremos das velocidades; não houve diferenças no ângulo do pico de torque. A espasticidade não interferiu na força dos músculos agonistas do movimento de flexão da articulação do cotovelo.The joint torque is an important variable related to children with cerebral palsy. The present study analyzed kinetic parameters during elbow flexion and extension movements in healthy and cerebral palsy children. Ten healthy and 10 cerebral palsy children participated of the study. An isokinetic dynamometer was used to measure the elbow mean peak torque, mean angle peak torque, coefficient of variation and acceleration during flexion and extension movements at different angular speeds. The mean peak torque on extension movement in healthy children group was significant higher compared to the cerebral palsy group. The coefficient of variation on both flexion and extension movements was significantly higher in cerebral palsy group. However there were significantly difference on both groups compared the lowest and highest velocities. Although the results showed no difference in flexor peak

Isokinetic strength testing does not predict hamstring injury in Australian Rules footballers

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Bennell, K.; Wajswelner, H.; Lew, P.; Schall-Riaucour, A.; Leslie, S.; Plant, D.; Cirone, J.

1998-01-01

OBJECTIVE: To determine the relation of hamstring and quadriceps muscle strength and imbalance to hamstring injury using a prospective observational cohort study METHOD: A total of 102 senior male Australian Rules footballers aged 22.2 (3.6) years were tested at the start of a football season. Maximum voluntary concentric and eccentric torque of the hamstring and quadriceps muscles of both legs was assessed using a Kin-Com isokinetic dynamometer at angular velocities of 60 and 180 degre...

Cardiorespiratory Fitness and Peak Torque Differences between Vegetarian and Omnivore Endurance Athletes: A Cross-Sectional Study

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Heidi M. Lynch

2016-11-01

Full Text Available In spite of well-documented health benefits of vegetarian diets, less is known regarding the effects of these diets on athletic performance. In this cross-sectional study, we compared elite vegetarian and omnivore adult endurance athletes for maximal oxygen uptake (VO2 max and strength. Twenty-seven vegetarian (VEG and 43 omnivore (OMN athletes were evaluated using VO2 max testing on the treadmill, and strength assessment using a dynamometer to determine peak torque for leg extensions. Dietary data were assessed using detailed seven-day food logs. Although total protein intake was lower among vegetarians in comparison to omnivores, protein intake as a function of body mass did not differ by group (1.2 ± 0.3 and 1.4 ± 0.5 g/kg body mass for VEG and OMN respectively, p = 0.220. VO2 max differed for females by diet group (53.0 ± 6.9 and 47.1 ± 8.6 mL/kg/min for VEG and OMN respectively, p < 0.05 but not for males (62.6 ± 15.4 and 55.7 ± 8.4 mL/kg/min respectively. Peak torque did not differ significantly between diet groups. Results from this study indicate that vegetarian endurance athletes’ cardiorespiratory fitness was greater than that for their omnivorous counterparts, but that peak torque did not differ between diet groups. These data suggest that vegetarian diets do not compromise performance outcomes and may facilitate aerobic capacity in athletes.

INTERSESSION RELIABILITY OF UPPER EXTREMITY ISOKINETIC PUSH-PULL TESTING.

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Riemann, Bryan L; Davis, Sarah E; Huet, Kevin; Davies, George J

2016-02-01

Based on the frequency pushing and pulling patterns are used in functional activities, there is a need to establish an objective method of quantifying the muscle performance characteristics associated with these motions, particularly during the later stages of rehabilitation as criteria for discharge. While isokinetic assessment offers an approach to quantifying muscle performance, little is known about closed kinetic chain (CKC) isokinetic testing of the upper extremity (UE). To determine the intersession reliability of isokinetic upper extremity measurement of pushing and pulling peak force and average power at slow (0.24 m/s), medium (0.43 m/s) and fast (0.61 m/s) velocities in healthy young adults. The secondary purpose was to compare pushing and pulling peak force (PF) and average power (AP) between the upper extremity limbs (dominant, non-dominant) across the three velocities. Twenty-four physically active men and women completed a test-retest (>96 hours) protocol in order to establish isokinetic UE CKC reliability of PF and AP during five maximal push and pull repetitions at three velocities. Both limb and speed orders were randomized between subjects. High test-retest relative reliability using intraclass correlation coefficients (ICC2, 1) were revealed for PF (.91-.97) and AP (.85-.95) across velocities, limbs and directions. PF typical error (% coefficient of variation) ranged from 6.1% to 11.3% while AP ranged from 9.9% to 26.7%. PF decreased significantly (p pushing were significantly greater than pulling at all velocities, however the push-pull differences in PF became less as velocity increased. There were no significant differences identified between the dominant and nondominant limbs. Isokinetically derived UE CKC push-pull PF and AP are reliable measures. The lack of limb differences in healthy normal participants suggests that clinicians can consider bilateral comparisons when interpreting test performance. The increase in pushing PF and

Hamstrings strength imbalance in professional football (soccer) players in Australia.

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Ardern, Clare L; Pizzari, Tania; Wollin, Martin R; Webster, Kate E

2015-04-01

The aim of this study was to describe the isokinetic thigh muscle strength profile of professional male football players in Australia. Concentric (60° and 240°·s(-1)) and eccentric (30° and 120°·s(-1)) hamstrings and quadriceps isokinetic strength was measured with a HUMAC NORM dynamometer. The primary variables were bilateral concentric and eccentric hamstring and quadriceps peak torque ratios, concentric hamstring-quadriceps peak torque ratios, and mixed ratios (eccentric hamstring 30°·s(-1) ÷ concentric quadriceps 240°·s(-1)). Hamstring strength imbalance was defined as deficits in any 2 of: bilateral concentric hamstring peak torque ratio imbalance. Athletes with strength imbalance had significantly reduced concentric and eccentric bilateral hamstring peak torque ratios at all angular velocities tested; and reduced eccentric quadriceps peak torque (30°·s(-1)) in their stance leg, compared with those without strength imbalance. Approximately, 1 in 4 players had preseason hamstring strength imbalance; and all strength deficits were observed in the stance leg. Concentric and eccentric hamstrings strength imbalance may impact in-season football performance and could have implications for the future risk of injury.

Isokinetic force of under-twenties soccer players: comparison of players in different field positions

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Raphael Mendes Ritti Dias

2007-06-01

Full Text Available During a soccer match, countless movements involving muscular force are performed. While some studies have analyzed the force exerted by soccer players, their results have been divergent, particularly when force has been analyzed with respect to fi eld positions. The objective of this study was to compare peak torque, total muscular work, maximum power and isokinetic fatigue index of the knee fl exor and extensor muscles of soccer players in a variety of fi eld positions. Seventy-eight under-twenty soccer players were classifi ed according to the position they play: goalkeepers (n=7, full backs (n=14, wingers (n=16, defensive midfi elders (n=11, center midfi elders (n=14 and forwards (n=16. The concentric isokinetic force of knee fl exor and extensor muscles was evaluated using an isokinetic dynamometer, Cybex® brand Norm™ 6000 model (CSMI, USA. Data was analyzed in terms of non-parametric statistics and results expressed in medians and semi-interquartile range. The Kruskal-Wallis test was applied and when results were signifi cant to pRESUMO Durante uma partida de futebol são realizados inúmeros movimentos que envolvem a força muscular. Embora alguns estudos tenham analisado a força de jogadores de futebol, os resultados encontrados têm sido controversos, principalmente quando analisada a força em função da posição de jogo. O objetivo deste estudo foi comparar o pico de torque, trabalho muscular total, potência máxima e índice de fadiga isocinético dos músculos fl exores e extensores de joelho de jogadores de futebol que atuam em diferentes posições de jogo. Foram incluídos 78 atletas de futebol, pertencentes à categoria Sub-20, foram agrupados de acordo com a posição em campo de jogo: goleiros (n=7, zagueiros (n=14, laterais (n=16, volantes (n=11, meio campo (n=14 e atacantes (n=16. Foi realizada avaliação da força isocinética concêntrica dos músculos fl exores e extensores de joelho em dinamômetro isocin

Enhanced precision of ankle torque measure with an open-unit dynamometer mounted with a 3D force-torque sensor.

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Toumi, A; Leteneur, S; Gillet, C; Debril, J-F; Decoufour, N; Barbier, F; Jakobi, J M; Simoneau-Buessinger, Emilie

2015-11-01

Many studies have focused on maximum torque exerted by ankle joint muscles during plantar flexion. While strength parameters are typically measured with isokinetic or isolated ankle dynamometers, these devices often present substantial limitations for the measurement of torque because they account for force in only 1 dimension (1D), and the device often constrains the body in a position that augments torque through counter movements. The purposes of this study were to determine the contribution of body position to ankle plantar-flexion torque and to assess the use of 1D and 3D torque sensors. A custom designed 'Booted, Open-Unit, Three dimension, Transportable, Ergometer' (B.O.T.T.E.) was used to quantify plantar flexion in two conditions: (1) when the participant was restrained within the unit (locked-unit) and (2) when the participant's position was independent of the ankle dynamometer (open-unit). Ten young males performed maximal voluntary isometric plantar-flexion contractions using the B.O.T.T.E. in open and locked-unit mechanical configurations. The B.O.T.T.E. was reliable with ICC higher than 0.90, and CV lower than 7 %. The plantar-flexion maximal resultant torque was significantly higher in the locked-unit compared with open-unit configuration (P torque sensor significantly underestimated the proper capacity of plantar-flexion torque production (P torque should be performed with an open-unit dynamometer mounted with a 3D sensor that is exclusive of accessory muscles but inclusive of all ankle joint movements.

Dissociated time course between peak torque and total work recovery following bench press training in resistance trained men.

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Ferreira, Diogo V; Gentil, Paulo; Ferreira-Junior, João B; Soares, Saulo R S; Brown, Lee E; Bottaro, Martim

2017-10-01

To evaluate the time course of peak torque and total work recovery after a resistance training session involving the bench press exercise. Repeated measures with a within subject design. Twenty-six resistance-trained men (age: 23.7±3.7years; height: 176.0±5.7cm; mass: 79.65±7.61kg) performed one session involving eight sets of the bench press exercise performed to momentary muscle failure with 2-min rest between sets. Shoulder horizontal adductors peak torque (PT), total work (TW), delayed onset muscle soreness (DOMS) and subjective physical fitness were measured pre, immediately post, 24, 48, 72 and 96h following exercise. The exercise protocol resulted in significant pectoralis major DOMS that lasted for 72h. Immediately after exercise, the reduction in shoulder horizontal adductors TW (25%) was greater than PT (17%). TW, as a percentage of baseline values, was also less than PT at 24, 48 and 96h after exercise. Additionally, PT returned to baseline at 96h, while TW did not. Resistance trained men presented dissimilar PT and TW recovery following free weight bench press exercise. This indicates that recovery of maximal voluntary contraction does not reflect the capability to perform multiple contractions. Strength and conditioning professionals should be cautious when evaluating muscle recovery by peak torque, since it can lead to the repetition of a training session sooner than recommended. Copyright © 2017. Published by Elsevier Inc.

No Differences Between Alter G-Trainer and Active and Passive Recovery Strategies on Isokinetic Strength, Systemic Oxidative Stress and Perceived Muscle Soreness After Exercise-Induced Muscle Damage.

Science.gov (United States)

Cooke, Matthew B; Nix, Carrie M; Greenwood, Lori D; Greenwood, Mike C

2018-03-01

Cooke, MB, Nix, C, Greenwood, L, and Greenwood, M. No Differences Between Alter G-Trainer and Active and Passive Recovery Strategies on Isokinetic Strength, Systemic Oxidative Stress and Perceived Muscle Soreness After Exercise-Induced Muscle Damage. J Strength Cond Res 32(3): 736-747, 2018-The incidence of muscle injuries is prevalent in elite sport athletes and weekend warriors and strategies that safely and effectively hasten recovery are highly desirable. The purpose of this study was to examine the differences between 3 recovery methods after eliciting muscle damage in recreationally active men relative to maximal isokinetic contractions, perceived muscle soreness, and psychological mood states. Twenty-five recreationally active men (22.15 ± 3.53 years, 75.75 ± 11.91 kg, 180.52 ± 7.3 cm) were randomly matched by V[Combining Dot Above]O2 peak (53.86 ± 6.65 ml·kg·min) and assigned to one of 3 recovery methods: anti-gravity treadmill (G-Trainer) (N = 8), conventional treadmill (N = 8) or static stretching (N = 9). Recovery methods were performed 30 minutes, 24, 48, and 72 hours after a 45-minute downhill run. Following eccentrically biased running, no significant differences were noted in isokinetic knee flexion and extension peak torque, systemic markers of muscle damage, oxidative stress and lipid peroxidation such as serum creatine kinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA), respectively, and subjective ratings of perceived muscle soreness between recovery methods. The G-Trainer group did however display a higher mood state as indicated by the Profile of Mood State global scores at 24 hours postexercise when compared to the conventional treadmill recovery group (p = 0.035). The improved mood state after the use of the anti-gravity treadmill may provide clinical relevance to other populations.

Effects of a single whole body cryotherapy (-110°C) bout on neuromuscular performance of the elbow flexors during isokinetic exercise.

Science.gov (United States)

Ferreira-Junior, J B; Vieira, C A; Soares, S R S; Guedes, R; Rocha Junior, V A; Simoes, H G; Brown, L E; Bottaro, M

2014-12-01

It has been demonstrated that body cooling may decrease neuromuscular performance. However, the effect of a single session of whole body cryotherapy (-110°C) on neuromuscular performance has not been well documented. Thus, the aim of this study was to evaluate the effects of a single exposure of WBC on elbow flexor neuromuscular performance. Thirteen physically active, healthy young men (age=27.9±4.2 years, mass=79.4±9.7 kg, height=176.7±5.2 cm) were randomly exposed to 2 different experimental conditions separated by a minimum of 72 h: 1) whole body cryotherapy- 3 min at -110°C; 2) control- 3 min at 21°C. All subjects were tested for maximal isokinetic elbow flexion at 60°.s(-1) 30 min before and 10 min after each condition. There were no significant differences in peak torque, average power, total work or muscle activity between conditions. Peak torque was lower at post-test compared to pre-test in both conditions (F=6.58, p=0.025). However, there were no differences between pre-test and post-test for any other variables. These results indicate that strength specialists, athletic trainers and physical therapists might utilize whole body cryotherapy before training or rehabilitation without compromising neuromuscular performance of the elbow flexors. © Georg Thieme Verlag KG Stuttgart · New York.

Muscle response to pneumatic hand tool torque reaction forces.

Science.gov (United States)

Radwin, R G; VanBergeijk, E; Armstrong, T J

1989-06-01

Surface electromyography was used for studying the effects of torque reaction force acting against the hand, on forearm muscle activity and grip force for five subjects operating right angle, air shut-off nutrunners. Four tools having increasing spindle torque were operated using short and long torque reaction times. Nutrunner spindle torque ranged between 30 Nm and 100 Nm. Short torque reaction time was considered 0.5 s while long torque reaction time was 2 s. Peak horizontal force was the greatest component of the reaction force acting against the hand and accounted for more than 97% of the peak resultant hand force. Peak hand force increased from 89 N for the smallest tool to 202 N for the largest tool. Forearm muscle rms EMG, scaled for grip force, indicated average flexor activity during the Torque-reaction phase was more than four times greater than the Pre-start and Post Shut-off phases, and two times greater than the Run-down phase. Flexor EMG activity during the Torque-reaction phase increased for increasing tool peak spindle torque. Average flexor rms EMG activity, scaled for grip force, during the Torque-reaction phase increased from 372 N for the 30 Nm nutrunner to 449 N for the 100 Nm nutrunner. Flexor rms EMG activity averaged during the Torque-reaction phase and scaled for grip force was 390 N for long torque reaction times and increased to 440 N for short torque reaction times. Flexor rms EMG integrated over the torque reaction phase was 839 Ns for long torque reaction times and decreased to 312 Ns for short torque reaction times. The average latency between tool spindle torque onset and peak initial flexor rms EMG for long torque reaction times was 294 ms which decreased to 161 ms for short torque reaction times. The average latency between peak tool spindle torque, just prior to tool shut-off, and peak final rms EMG for long torque reaction times was 97 ms for flexors and 188 ms for extensors, which decreased for short torque reaction times to 47

Effect of voluntary vs. artificial activation on the relationship of muscle torque to speed

Science.gov (United States)

Dudley, Gary A.; Harris, Robert T.; Duvoisin, Marc R.; Hather, Bruce M.; Buchanan, Paul

1990-01-01

The suggestion by Phillips and Petrofsky (1980) and Wickiewicz et al. (1984) that artificial activation of the knee extensor muscles should result in greater relative changes in torque than those evident with maximal voluntary activation is examined by investigating the speed-torque relationship of the right knee extensor muscle group in eight human subjects in whom activation was achieved by 'maximal' voluntary effort or by electrical stimulation. Torque was measured at a specific knee angle during isokinetic concentric or eccentric actions at velocities between 0.17 and 3.66 rad/s and during isometric actions. It is shown that, with artificial activation, the relative changes in both eccentric and concentric torque were greater as the speed increased; the speed-torque relationship was independed of the extent of activation and was similar to that of an isolated muscle. On the other hand, activation by the central nervous system during maximal effort depended on the speed and the type of muscle action performed.

A 12-week rehabilitation program improves body composition, pain sensation, and internal/external torques of baseball pitchers with shoulder impingement symptom.

Science.gov (United States)

Cha, Jun-Youl; Kim, Jae-Hak; Hong, Ju; Choi, Young-Tae; Kim, Min-Ho; Cho, Ji-Hyun; Ko, Il-Gyu; Jee, Yong-Seok

2014-02-01

The aim of this study was to investigate the effects of a 12-week rehabilitation program on body composition, shoulder pain, and isokinetic internal/external torques of pitchers with impingement syndrome. A total of 30 pitchers were divided into 2 groups: experimental group (EG, n = 16) and control group (CG, n= 14). The rehabilitation program consisted of physical therapy, warm-up, work-out, and cool-down. As results, body weight and fat mass of EG were decreased whereas muscle mass of EG was significantly increased after the experiment. The pain degrees in resting, normal daily activity, and strenuous activity on the numeric pain rating scale were significantly decreased in the EG. The internal and external peak torques (PTs) of uninvolved and involved sides of EG were increased in EG after 12 weeks. Such results provide a deficit ratio of both sides in EG close to normal values. The ratios of internal/external PTs in EG were also close to the reference values. The internal and external total works of both sides in EG were similar to the values of PT. The fatigue indices of internal and external rotators of both sides in EG were decreased. As a conclusion, a 12-week rehabilitation program reduced the shoulder pain, improved the body composition and enhanced the isokinetic shoulder internal/external rotators in EG with impingement symptoms. Also the study suggested that the rehabilitation program evened out the ratio between internal and external rotators and lowered the fatigue level after the experiment.

Four-bar linkage-based automatic tool changer: Dynamic modeling and torque optimization

International Nuclear Information System (INIS)

Lee, Sangho; Seo, TaeWon; Kim, Jong-Won; Kim, Jongwon

2017-01-01

An Automatic tool changer (ATC) is a device used in a tapping machine to reduce process time. This paper presents the optimization of a Peak torque reduction mechanism (PTRM) for an ATC. It is necessary to reduce the fatigue load and energy consumed, which is related to the peak torque. The PTRM uses a torsion spring to reduce the peak torque and was applied to a novel ATC mechanism, which was modeled using inverse dynamics. Optimization of the PTRM is required to minimize the peak torque. The design parameters are the initial angle and stiffness of the torsion spring, and the objective function is the peak torque of the input link. The torque was simulated, and the peak torque was decreased by 10 %. The energy consumed was reduced by the optimization.

Four-bar linkage-based automatic tool changer: Dynamic modeling and torque optimization

Energy Technology Data Exchange (ETDEWEB)

Lee, Sangho; Seo, TaeWon [Yeungnam University, Gyeongsan (Korea, Republic of); Kim, Jong-Won; Kim, Jongwon [Seoul National University, Seoul (Korea, Republic of)

2017-05-15

An Automatic tool changer (ATC) is a device used in a tapping machine to reduce process time. This paper presents the optimization of a Peak torque reduction mechanism (PTRM) for an ATC. It is necessary to reduce the fatigue load and energy consumed, which is related to the peak torque. The PTRM uses a torsion spring to reduce the peak torque and was applied to a novel ATC mechanism, which was modeled using inverse dynamics. Optimization of the PTRM is required to minimize the peak torque. The design parameters are the initial angle and stiffness of the torsion spring, and the objective function is the peak torque of the input link. The torque was simulated, and the peak torque was decreased by 10 %. The energy consumed was reduced by the optimization.

The reliabilty of isokinetic strength measurement

OpenAIRE

Kadlec, Miroslav

2011-01-01

Title: Reliability of isometric and isokinetic strength testing in the knee flexion and extension Objectives: To compare the reliability of isometric and isokinetic testing of the knee strength in flexion and extension Methods: I used intraclass correlation coefficient and Pearson's correlation coefficient. Results: I have discovered that the reliability measured on isokinetic and isometric dynamometer is high. Furthermore the reliability of the maximum strength measurement was higher with-us...

Muscle torque of healthy individuals and individuals with spastic hemiparesis after passive static streching.

Science.gov (United States)

Tatsukawa DE Freitas, Sérgio Takeshi; DE Carvalho Abreu, Elizângela Márcia; Dos Reis, Mariane Cecilia; DE Souza Cunha, Bruna; Souza Moreira Prianti, Tamires; Pupio Silva Lima, Fernanda; Oliveira Lima, Mário

2016-01-01

Spasticity is one of the main causes of contracture, muscle weakness and subsequent functional incapacity. The passive static stretching can be included as having the purpose of increasing musculoskeletal flexibility, however, it also can influence the muscle torque. The objective is to verify the immediate effect of passive static stretching in the muscle strength of healthy and those who present spastic hemiparesis. There were assessed 20 subjects, 10 spastic hemiparetic (EG) and 10 healthy individuals (CG), including both sexes, aged between 22 and 78 years. The torque of extensor muscles of the knee was analyzed using isokinetic dynamometer. Results have shown that EG has less muscle torque compared to CG ( p torque after stretching ( p torque of CG after performing the program that was prescribed. Immediately after the passive stretch, a significant torque decrease can be seen in hypertonic muscle; it is believed that this reduction may be associated with the physiological overlap between actin and myosin filaments and so preventing the muscle to develop a maximum contraction.

The Relationship of Temperature to Strength and Power Production in Intact Human Skeletal Muscle.

Science.gov (United States)

1979-06-01

newton- meters (Nm). The use of the Cybex II isokinetic device has been similarly described by Thorstensson et al. (1976). The peak torque value, or the... isokinetic testing device at four lever arm speeds (0,60,180 and 300*/sec).Maximal knee exter- sions at the different lever arm speeds were evaluated for...Each subject was tested on the Cybex II isokinetic testing device at four lever arm speeds (0,60,180 and $Osec).Maximal knee exten- sions at the

Cardiorespiratory Fitness and Peak Torque Differences between Vegetarian and Omnivore Endurance Athletes: A Cross-Sectional Study.

Science.gov (United States)

Lynch, Heidi M; Wharton, Christopher M; Johnston, Carol S

2016-11-15

In spite of well-documented health benefits of vegetarian diets, less is known regarding the effects of these diets on athletic performance. In this cross-sectional study, we compared elite vegetarian and omnivore adult endurance athletes for maximal oxygen uptake (VO2 max) and strength. Twenty-seven vegetarian (VEG) and 43 omnivore (OMN) athletes were evaluated using VO2 max testing on the treadmill, and strength assessment using a dynamometer to determine peak torque for leg extensions. Dietary data were assessed using detailed seven-day food logs. Although total protein intake was lower among vegetarians in comparison to omnivores, protein intake as a function of body mass did not differ by group (1.2 ± 0.3 and 1.4 ± 0.5 g/kg body mass for VEG and OMN respectively, p = 0.220). VO2 max differed for females by diet group (53.0 ± 6.9 and 47.1 ± 8.6 mL/kg/min for VEG and OMN respectively, p vegetarian endurance athletes' cardiorespiratory fitness was greater than that for their omnivorous counterparts, but that peak torque did not differ between diet groups. These data suggest that vegetarian diets do not compromise performance outcomes and may facilitate aerobic capacity in athletes.

Pain severity is associated with muscle strength and peak oxygen uptake in adults with fibromyalgia

Directory of Open Access Journals (Sweden)

Hooten WM

2014-05-01

Full Text Available W Michael Hooten,1,2 Jolene M Smith,3 Jason S Eldrige,1 David A Olsen,3 W David Mauck,1 Susan M Moeschler11Department of Anesthesiology, 2Department of Psychiatry and Psychology, Mayo Clinic College of Medicine, 3Mayo School of Graduate Medical Education, Rochester, MN, USABackground: The associations between pain, lower extremity strength, and aerobic conditioning have not been widely investigated in adults with fibromyalgia (FM. The principle objective of this study was to investigate the relationship between pain severity and knee strength in patients seeking treatment for FM. A secondary objective was to investigate the relationship between pain scores and aerobic conditioning.Methods: Three measures of knee strength (isokinetic extensor, isokinetic flexor, isometric extensor were quantified in the dominant leg of 69 adults with FM using a dynamometer at speeds of 60 degrees per second (60°/s and 180°/s. Peak oxygen uptake (VO2 was assessed using a cycle ergometer, and pain was assessed using the pain severity subscale of the Multidimensional Pain Inventory.Results: In univariable linear regression analyses using pain severity as the dependent variable, lesser values of isokinetic knee extensor strength at 60°/s (P=0.041 and 180°/s (P=0.010, isokinetic knee flexor strength at 60°/s (P=0.028 and 180°/s (P=0.003, and peak VO2 uptake (P=0.031 were predictive of greater pain severity scores. In multiple variable linear regression models adjusted for age, sex, body mass index, and opioid use, the following associations retained statistical significance; isokinetic knee extensor strength at 60°/s (P=0.020 and 180°/s (P=0.003, isokinetic knee flexor strength at 60°/s (P=0.015 and 180°/s (P=0.001, and peak VO2 uptake (P=0.014. However, no significant associations were found between pain severity and isometric knee extensor strength.Conclusion: The main findings from this study were that lesser values of isokinetic knee strength and peak VO

The effect of warm-ups with stretching on the isokinetic moments of collegiate men.

Science.gov (United States)

Park, Hyoung-Kil; Jung, Min-Kyung; Park, Eunkyung; Lee, Chang-Young; Jee, Yong-Seok; Eun, Denny; Cha, Jun-Youl; Yoo, Jaehyun

2018-02-01

Performing warm-ups increases muscle temperature and blood flow, which contributes to improved exercise performance and reduced risk of injuries to muscles and tendons. Stretching increases the range of motion of the joints and is effective for the maintenance and enhancement of exercise performance and flexibility, as well as for injury prevention. However, stretching as a warm-up activity may temporarily decrease muscle strength, muscle power, and exercise performance. This study aimed to clarify the effect of stretching during warm-ups on muscle strength, muscle power, and muscle endurance in a nonathletic population. The subjects of this study consisted of 13 physically active male collegiate students with no medical conditions. A self-assessment questionnaire regarding how well the subjects felt about their physical abilities was administered to measure psychological readiness before and after the warm-up. Subjects performed a non-warm-up, warm-up, or warm-up regimen with stretching prior to the assessment of the isokinetic moments of knee joints. After the measurements, the respective variables were analyzed using nonparametric tests. First, no statistically significant intergroup differences were found in the flexor and extensor peak torques of the knee joints at 60°/sec, which were assessed to measure muscle strength. Second, no statistically significant intergroup differences were found in the flexor and extensor peak torques of the knee joints at 180°/sec, which were assessed to measure muscle power. Third, the total work of the knee joints at 240°/sec, intended to measure muscle endurance, was highest in the aerobic-stretch-warm-ups (ASW) group, but no statistically significant differences were found among the groups. Finally, the psychological readiness for physical activity according to the type of warm-up was significantly higher in ASW. Simple stretching during warm-ups appears to have no effect on variables of exercise physiology in nonathletes

Effect of plyometric training on lower limb biomechanics in females.

Science.gov (United States)

Baldon, Rodrigo de Marche; Moreira Lobato, Daniel F; Yoshimatsu, Andre P; dos Santos, Ana Flávia; Francisco, Andrea L; Pereira Santiago, Paulo R; Serrão, Fábio V

2014-01-01

To verify the effects of plyometric training on lower limb kinematics, eccentric hip and knee torques, and functional performance. Cohort study. Research laboratory. Thirty-six females were divided into a training group (TG; n = 18) that carried out the plyometric training for 8 weeks, and a control group (CG; n = 18) that carried out no physical training. Twenty-four plyometric training sessions during approximately 8 weeks with 3 sessions per week on alternate days. Lower limb kinematics (maximum excursion of hip adduction, hip medial rotation, and knee abduction during the single leg squat), eccentric hip (abductor, adductor, medial, and lateral rotator) isokinetic peak torques and knee (flexor and extensor) isokinetic peak torques, and functional performance (triple hop test and the 6-m timed hop test). After 8 weeks, only the TG significantly reduced the values for the maximum excursion of knee abduction (P = 0.01) and hip adduction (P Plyometric training alters lower limb kinematics and increases eccentric hip torque and functional performance, suggesting the incorporation of these exercises in preventive programs for ACL injuries.

Torque and mechanomyogram relationships during electrically-evoked isometric quadriceps contractions in persons with spinal cord injury.

Science.gov (United States)

Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Hasnan, Nazirah; Abdul Wahab, Ahmad Khairi; Islam, Md Anamul; Kean, Victor S P; Davis, Glen M

2016-08-01

The interaction between muscle contractions and joint loading produces torques necessary for movements during activities of daily living. However, during neuromuscular electrical stimulation (NMES)-evoked contractions in persons with spinal cord injury (SCI), a simple and reliable proxy of torque at the muscle level has been minimally investigated. Thus, the purpose of this study was to investigate the relationships between muscle mechanomyographic (MMG) characteristics and NMES-evoked isometric quadriceps torques in persons with motor complete SCI. Six SCI participants with lesion levels below C4 [(mean (SD) age, 39.2 (7.9) year; stature, 1.71 (0.05) m; and body mass, 69.3 (12.9) kg)] performed randomly ordered NMES-evoked isometric leg muscle contractions at 30°, 60° and 90° knee flexion angles on an isokinetic dynamometer. MMG signals were detected by an accelerometer-based vibromyographic sensor placed over the belly of rectus femoris muscle. The relationship between MMG root mean square (MMG-RMS) and NMES-evoked torque revealed a very high association (R(2)=0.91 at 30°; R(2)=0.98 at 60°; and R(2)=0.97 at 90° knee angles; Ptorque, between 0.65 and 0.79 for MMG-RMS, and from 0.67 to 0.73 for MMG-PTP. Their standard error of measurements (SEM) ranged between 10.1% and 31.6% (of mean values) for torque, MMG-RMS and MMG-PTP. The MMG peak frequency (MMG-PF) of 30Hz approximated the stimulation frequency, indicating NMES-evoked motor unit firing rate. The results demonstrated knee angle differences in the MMG-RMS versus NMES-isometric torque relationship, but a similar torque related pattern for MMG-PF. These findings suggested that MMG was well associated with torque production, reliably tracking the motor unit recruitment pattern during NMES-evoked muscle contractions. The strong positive relationship between MMG signal and NMES-evoked torque production suggested that the MMG might be deployed as a direct proxy for muscle torque or fatigue measurement during

Improvement of Torque Production in Single-Phase Induction Motors

African Journals Online (AJOL)

OLUWASOGO

PID controller. Simulation results show the starting torque of the motor increased by 75% under the developed drive scheme. In addition, torque pulsations reduced from 1.4 Nm peak-peak to 0.14 Nm peak-peak at steady state. It was observed that the accelerating time reduced by 30% compared to the accelerating time ...

Assessing the therapeutic effect of 625-nm light-emitting diodes

Science.gov (United States)

Mao, Zongzhen; Xu, Guodong; Yang, Yi

2014-09-01

To evaluate the effects of red Light-Emitting Diodes on elbow extensor and flexor strength and the recovery of exercise induced fatigue, the torque values from the isokinetic dynamometer as well as biochemistry parameters were used as outcome measures. A randomized double-blind placebo-controlled crossover trial was performed with twenty male young tennis athletes. Active LED therapy (LEDT, with wavelength 625nm, 10 minutes total irradiation time, irradiated area amount to 30cm2, and 900J of total energy irradiated) or an identical placebo was delivered under double-blinded conditions to the left elbow just before exercise. The isokinetic muscle strength was measured immediately after irradiation. The blood lactate levels were sampled pre-exercise and post-exercise. The peak torque values of elbow extensor strength were significantly different between two groups. As in elbow flexor strength, the difference of peak torque was not significant. The blood lactate concentration of LEDT group post-exercise was significantly lower than those of placebo group. The results indicate that 625nm LED therapy is effective in preventing muscle fatigue as it can significantly reduce peak torque value of elbow extensors and blood lactate concentration. It has no effect on the strength of left elbow flexor or backhand performance in tennis.

Preference and torque asymmetry for elbow joint Preferência e assimetria de torque na articulação do cotovelo

Directory of Open Access Journals (Sweden)

Felipe Pivetta Carpes

2012-06-01

Full Text Available Extensively unilateral recruitment for daily activities may determine performance asymmetries in favor of the preferred side eliciting functional adaptation. Our study evaluated asymmetries in elbow torque output between preferred and non-preferred limbs. Eighteen subjects performed maximal elbow flexor and extensor isometric contractions at five different elbow joint angles (0º, 30º, 60º, 90º, 120º and five different angular velocities (60, 120, 180, 240, 300º.s-1 on an isokinetic dynamometer. Higher flexor torque in favor of preferred arm was observed at 90º of flexion (pO frequente recrutamento unilateral de membros superiores pode determinar assimetrias de desempenho em favor do lado preferido, resultando em adaptação funcional. Assimetrias no torque gerado pelos músculos do cotovelo entre o membro preferido e não-preferido foram avaliadas. Dezoito sujeitos realizaram contrações máximas de flexo-extensão do cotovelo em cinco ângulos articulares (0º, 30º, 60º, 90º, 120º e cinco velocidades angulares (60, 120, 180, 240, 300º.s-1 em um dinamômetro isocinético. Torque flexor mais elevado em favor do lado preferido foi encontrado no ângulo de 90º (p<0,05, que também correspondeu ao ângulo de maior torque (p<0,05. O fato de o ângulo articular determinar assimetrias no torque (enquanto a velocidade angular não sugere que o recrutamento preferencial dos flexores do cotovelo em um ângulo de 90º nas tarefas da vida diária que requerem força elevada é responsável pela assimetria. Adaptação funcional a estímulos frequentes nesse ângulo articular pode explicar esses resultados em sujeitos saudáveis.

Isokinetic strength and endurance after percutaneous and open surgical repair of Achilles tendon ruptures.

Science.gov (United States)

Goren, David; Ayalon, Moshe; Nyska, Meir

2005-04-01

Reports on complete spontaneous Achilles tendon ruptures and associated treatment have become more frequent in the literature in the past two decades, as has the request for treatments that enable the finest possible functional recovery. The best available treatment is a matter of considerable controversy in the literature. The purpose of this study was to compare the isokinetic strength and endurance of the plantarflexor muscle-tendon unit in subjects who sustained rupture of the Achilles tendon and underwent either open surgery or closed percutaneous repair of the Achilles tendon. Twenty patients (18 males, 2 females) with spontaneous ruptures of the Achilles tendon were included in this study. Ten patients were treated by open surgery, and 10 patients were treated percutaneously. All patients had ruptured their Achilles tendon more than 6 months before the study, and all of the ruptures occurred 3.5 years or less before the day of the testing. All patients underwent an oriented physical examination. An isokinetic Biodex dynamometer (Biodex Medical System, Shirley, NY) was used to measure ankle joint angle, and in plantarflexion to calculate the torque at the ankle joint (Newton/meter), and the average work (jouls) for both maximal power and endurance. Each measurement was compared to the normal ankle. Biodex dynamometer evaluations at 90 deg/sec demonstrated a significant difference of maximal voluntary plantarflexor torque, endurance performance and range of motion at the ankle joint between the involved and uninvolved sides in patients treated by either mode of treatment. Yet, no statistically significant differences were revealed for the parameters mentioned above between the subjects that were treated either percutaneously or by an open surgery. In functional terms, the biomechanical outcomes of open surgery and percutaneous repair for acute ruptures of the Achilles tendon are both effective.

Estimation of Electrically-Evoked Knee Torque from Mechanomyography Using Support Vector Regression

Directory of Open Access Journals (Sweden)

Morufu Olusola Ibitoye

2016-07-01

Full Text Available The difficulty of real-time muscle force or joint torque estimation during neuromuscular electrical stimulation (NMES in physical therapy and exercise science has motivated recent research interest in torque estimation from other muscle characteristics. This study investigated the accuracy of a computational intelligence technique for estimating NMES-evoked knee extension torque based on the Mechanomyographic signals (MMG of contracting muscles that were recorded from eight healthy males. Simulation of the knee torque was modelled via Support Vector Regression (SVR due to its good generalization ability in related fields. Inputs to the proposed model were MMG amplitude characteristics, the level of electrical stimulation or contraction intensity, and knee angle. Gaussian kernel function, as well as its optimal parameters were identified with the best performance measure and were applied as the SVR kernel function to build an effective knee torque estimation model. To train and test the model, the data were partitioned into training (70% and testing (30% subsets, respectively. The SVR estimation accuracy, based on the coefficient of determination (R2 between the actual and the estimated torque values was up to 94% and 89% during the training and testing cases, with root mean square errors (RMSE of 9.48 and 12.95, respectively. The knee torque estimations obtained using SVR modelling agreed well with the experimental data from an isokinetic dynamometer. These findings support the realization of a closed-loop NMES system for functional tasks using MMG as the feedback signal source and an SVR algorithm for joint torque estimation.

ISOKINETIC COMPARISON OF THE ROTATOR CUFF BETWEEN WATERPOLO AND TENNIS PLAYERS/ COMPARAREA ISOKINETICĂ A COIFULUI ROTATORILOR ÎNTRE JUCĂTORII DE POLLO ŞI CEI DE TENIS

Directory of Open Access Journals (Sweden)

Linde FJ

Full Text Available Isokinetic evaluation is an objective method that allows rapid and reliable comparison of the relationship between the muscle groups of the rotator cuff, during dynamic exercise. At shoulder level, balance between the rotator cuff muscle groups is essential for keeping joint stability. The purpose of this study is to detect significant differences in muscular performance strength values of the muscles of the rotator cuff by isokinetic tests, in two overhead sport specialities: water polo and tennis. Comparison could be realized analyzing various parameters derivate of the test. Material and methods. We undertook an isokinetic study in a group of 36 high-level athletes: 30 water polo players (12 women and 18 men and 6 tennis players (2 women and 4 men. The parameters analyzed were: peak torque (PT, maximal repetition work (MRW, muscle asymmetry between dominant and no dominant shoulder, and ratio between external and internal rotators. Results. For all tested values of PT, the dominant limb has always been stronger than the no dominant in both sports, but differences in tennis players were much higher in favor of the dominant than water polo players with specific reference to IR. With regard to MRW, water polo players had values higher than tennis players in ER of both sides, but the IR of the dominant limb is greater in tennis players. Conclusions. In water polo players, due to the environment in which specific work is developed and the symmetrical content of simming, the ratios in both extremities were very symmetrical (related to PT; in tennis players, the dominant limb had more normal ratio values but this doesn’t happen in the no dominant possibly because it comes into play shortly.

Thermomagnetic torque in hydrogen isotopes

International Nuclear Information System (INIS)

Cramer, J.A.

1975-01-01

The thermomagnetic torque has been measured in parahydrogen and ortho and normal deuterium for pressures from 0.10 to 2.0 torr and temperatures from 100 to 370 K. Since the torque depends on the precession of the molecular rotational magnetic moment around the field direction, coupling of the molecular nuclear spin to the rotational moment can affect the torque. Evidence of spin coupling effects is found for the torque in both deuterium modifications. In para hydrogen the torque at all temperatures and pressures exhibits behavior expected of a gas of zero nuclear spin molecules. Additionally, earlier data for hydrogen deuteride and for normal hydrogen from 105 to 374 K are evaluated and discussed. The high pressure limiting values of torque peak heights and positions for all these gases are compared with theory

Shoulder rotator isokinetic strength profile in young swimmers

Directory of Open Access Journals (Sweden)

Nuno Miguel Prazeres Batalha

2012-08-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n5p545  Considering that some studies suggest that shoulder rotators muscle imbal­ances are related to joint pain and injury, and that there are no normative data for young swimmers, the aim of this study was: i to describe the muscle balance, fatigue and isokinetic strength profile of the shoulder rotators in young swimmers; ii to compare the results between swimmers and a group of young non-practitioners; iii to contribute to the acquisition of normative data of unilateral ratios of shoulder rotators. We evaluated the shoulder rotators concentric strength and unilateral ratios (ratio between torque of external and internal rotators of 60 swimmers (age: 14.55 ± 0.5 years old; body mass: 61.16 ± 7.08 kg and 60 non-practitioners (age: 14.62 ± 0.49 years old; body mass: 60.22 ± 10.01 kg. The evaluation was performed in the sitting position (90° abduction and elbow flexion at 60º.s-1 and 180º.s-1 angular speeds using an isokinetic dynamometer (Biodex System 3. The results of the fatigue ratios revealed no differences between the groups. Swimmers showed unilateral ratios of 73.39 ± 17.26% in the dominant limb (DL and 77.89 ± 15,23% in the non-dominant limb (NDL for assessments at 60º.s-1. At 180º.s-1, ratios were 74.77± 13.99% for DL and 70.11 ± 14.57% for NDL. Swimmers presented greater muscle imbalance, and differed from non-practitioners in the ability to produce power with the internal rotators, which was significantly higher in the former group.

Torque-onset determination: Unintended consequences of the threshold method.

Science.gov (United States)

Dotan, Raffy; Jenkins, Glenn; O'Brien, Thomas D; Hansen, Steve; Falk, Bareket

2016-12-01

Compared with visual torque-onset-detection (TOD), threshold-based TOD produces onset bias, which increases with lower torques or rates of torque development (RTD). To compare the effects of differential TOD-bias on common contractile parameters in two torque-disparate groups. Fifteen boys and 12 men performed maximal, explosive, isometric knee-extensions. Torque and EMG were recorded for each contraction. Best contractions were selected by peak torque (MVC) and peak RTD. Visual-TOD-based torque-time traces, electromechanical delays (EMD), and times to peak RTD (tRTD) were compared with corresponding data derived from fixed 4-Nm- and relative 5%MVC-thresholds. The 5%MVC TOD-biases were similar for boys and men, but the corresponding 4-Nm-based biases were markedly different (40.3±14.1 vs. 18.4±7.1ms, respectively; ptorque kinetics tended to be faster than the boys' (NS), but the 4-Nm-based kinetics erroneously depicted the boys as being much faster to any given %MVC (p<0.001). When comparing contractile properties of dissimilar groups, e.g., children vs. adults, threshold-based TOD methods can misrepresent reality and lead to erroneous conclusions. Relative-thresholds (e.g., 5% MVC) still introduce error, but group-comparisons are not confounded. Copyright © 2016 Elsevier Ltd. All rights reserved.

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios

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Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

2015-01-01

AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P hamstring muscle strength at both the 60°/s and 180°/s test speeds (P 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05). CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines. PMID:26495249

Body Mass Bias in a Combat Fitness Test

Science.gov (United States)

2011-02-07

Allometric scaling of isokinetic peak torque: The Nebraska Wrestling Study. European Journal of Applied Physiology, 80, 240–248. White, C. R...applied to the Movement and 3-mi run times after converting times to velocity (in meters ). The estimated metabolic rate mass coefficients were

Isokinetic imbalance of adductor-abductor hip muscles in professional soccer players with chronic adductor-related groin pain.

Science.gov (United States)

Belhaj, K; Meftah, S; Mahir, L; Lmidmani, F; Elfatimi, A

2016-11-01

This study aims to compare the isokinetic profile of hip abductor and adductor muscle groups between soccer players suffering from chronic adductor-related groin pain (ARGP), soccer players without ARGP and healthy volunteers from general population. Study included 36 male professional soccer players, who were randomly selected and followed-up over two years. Of the 21 soccer players eligible to participate in the study, 9 players went on to develop chronic ARGP and 12 players did not. Ten healthy male volunteers were randomly selected from the general population as a control group. Comparison between the abductor and adductor muscle peak torques for players with and without chronic ARGP found a statistically significant difference on the dominant and non-dominant sides (p muscle significantly stronger than the adductor muscle. In the group of healthy volunteers, the adductor muscle groups were significantly stronger than the abductor muscle groups on both dominant and non-dominant sides (p muscle strength was also significantly decreased on the affected side. This imbalance appears to be a risk factor for adductor-related groin injury. Therefore, restoring the correct relationship between these two agonist and antagonist hip muscles may be an important preventative measure that should be a primary concern of training and rehabilitation programmes.

Isokinetic and isometric strength-endurance after 6 hours of immersion and 6 degrees head-down tilt in men

Science.gov (United States)

Shaffer-Bailey, M.; Greenleaf, J. E.; Hutchinson, T. M.

1996-01-01

PURPOSE: To determine weight (water) loss levels for onset of muscular strength and endurance changes during deconditioning. METHODS: Seven men (27-40 yr) performed maximal shoulder-, knee-, and ankle-joint isometric (0 degree.s(-1) load) and isokinetic (60 degrees, 120 degrees, 180 degrees.s(-1) velocity) exercise tests during ambulatory control (AC), after 6 h of 6 degrees head-down tilt (HDT; dry-bulb temp. = 23.2 +/- SD 0.6 degrees C, relative humidity = 31.1+/- 11.1%) and after 6 h of 80 degrees foot-down head-out water immersion (WI; water temp. = 35.0 +/- SD 0.1 degree C) treatments. RESULTS: Weight (water) loss after HDT (1.10 +/- SE 0.14 kg, 1.4 +/- 0.2% body wt) and WI (1.54+/- 0.19 kg, 2.0 +/- 0.2% body wt) were not different, but urinary excretion with WI (1,354 +/- 142 ml.6 h(-1)) was 28% greater (p strength was unchanged except for three knee-joint peak torques: AC torque (120 degrees.s(-1), 285 +/- 20 Nm) decreased to 268 +/- 21 Nm (delta = -6%, p strength and endurance decrements is more than 2% body weight (water) loss, while significant reduction in knee-joint muscular strength-endurance occurred only at moderate (120 degrees.s(-1) and lighter (180 degrees.s(-1)) loads with body weight loss of 1.4-2.0% following WI or HDT, respectively. These weight (water) losses and knee-joint strength decrements are somewhat less than the mean weight loss of 2.6% and knee-joint strength decrements of 6-20% of American astronauts after Skylab flights to 84 d.

Seasonal variation in isokinetic strength of knee flexors and extensors in soccer players

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Michal Lehnert

2015-06-01

Full Text Available BACKGROUND: Muscle strength is an important factor in soccer from the performance and health perspective. There is a lack of knowledge about changes in muscle strength of the knee flexors and extensors and their ratios during annual training cycle. OBJECTIVES: The aim of this study was to evaluate the seasonal variability of the observed parameters of isokinetic strength of the knee flexors and extensors in soccer players, U19, from the performance and health perspective. METHODS: The strength of the knee flexors and extensors was measured in players U19 category (n = 9; the average age 18.5 ±0.4 years on the isokinetic dynamometer IsoMed 2000 in angular velocity 60° × s-1. Measurement was performed in concentric/concentric and excentric/excentric mode of muscle action at the beginning of the winter preparatory period, at the end of the preparatory period and at the end of the spring competitive period. Monitored parameters were absolute peak torque (PT, conventional H/Q ratio (H/QCON, functional H/Q ratio (H/QFUN and functional H/Q ratio in range 10-30° of knee flexion (H/QFUN_10-30. RESULTS: Significant change in PT (p < .05 was noted only in cases of the knee extensors of the nondominant leg in the concentric mode. The evaluation of imbalance of the knee flexors and extensors by H/QCON and H/QFUN ratios did not show any significant changes, but there was found a significant decrease of the H/QFUN_10-30 ratio in the dominant leg between measurements at the beginning and at the end of the winter preparatory period. CONCLUSIONS: The results of the current study indicate that throughout the monitored periods of the annual training cycle desirable changes in knee flexors and extensors strength did not occur. The values suggest the disruption of the dynamic stabilization of the knee joint and increase in injury risk. Different dynamics of the three observed ratios confirmed that they provide different information about the physical fitness of

Myocellular enzyme leakage, polymorphonuclear neutrophil activation and delayed onset muscle soreness induced by isokinetic eccentric exercise.

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Croisier, J L; Camus, G; Deby-Dupont, G; Bertrand, F; Lhermerout, C; Crielaard, J M; Juchmès-Ferir, A; Deby, C; Albert, A; Lamy, M

1996-01-01

To address the question of whether delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of the arachidonic acid derived product prostaglandin E2 (PGE2). 10 healthy male subjects were submitted to eccentric and concentric isokinetic exercises on a Kin Trex device at 60 degrees/s angular velocity. Exercise consisted of 8 stages of 5 maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases. There was an interval of at least 30 days between eccentric and concentric testing, and the order of the two exercise sessions was randomly assigned. The subjective presence and intensity of DOMS was evaluated using a visual analogue scale, immediately, following 24 h and 48 h after each test. Five blood samples were drawn from an antecubital vein: at rest before exercise, immediately after, after 30 min recovery, 24 h and 48 h after the tests. The magnitude of the acute inflammatory response to exercise was assessed by measuring plasma levels of polymorphonuclear elastase ([EL]), myeloperoxidase ([MPO]) and PGE2 ([PGE2]). Using two way analysis of variance, it appeared that only eccentric exercise significantly increased [EL] and DOMS, especially of the hamstring muscles. Furthermore, a significant decrease in eccentric peak torque of this muscle group only was observed on day 2 after eccentric work (- 21%; P < 0.002). Serum activity of creatine kinase and serum concentration of myoglobin increased significantly 24 and 48 h after both exercise tests. However, these variables reached significantly higher values following eccentric contractions 48 h after exercise. Mean [PGE2] in the two exercise modes remained unchanged over time and were practically equal at each time point. On the basis of these findings, we conclude that the magnitude of polymorphonuclear (PMN) activation, muscle damage, and DOMS are greater after eccentric than after concentric muscle

Lower extremity injury in female basketball players is related to a large difference in peak eversion torque between barefoot and shod conditions

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Jennifer M. Yentes

2014-09-01

Conclusion: It is possible that a large discrepancy between strength in barefoot and shod conditions can predispose an athlete to injury. Narrowing the difference in peak eversion torque between barefoot and shod could decrease propensity to injury. Future work should investigate the effect of restoration of muscular strength during barefoot and shod exercise on injury rates.

Recovery of pectoralis major and triceps brachii after bench press exercise.

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Ferreira, Diogo V; Gentil, Paulo; Soares, Saulo Rodrigo Sampaio; Bottaro, Martim

2017-11-01

The present study evaluated and compared the recovery of pectoralis major (PM) and triceps brachii (TB) muscles of trained men after bench press exercise. Eighteen volunteers performed eight sets of bench press exercise to momentary muscle failure and were evaluated for TB and PM peak torque and total work on an isokinetic dynamometer. PM peak torque and total work remained lower than baseline for 72 and 96 h, respectively. TB peak torque was only different from baseline immediately post training, while total work was significantly lower than baseline immediately and 48 h after training. Normalized peak torque values were only different between TB and PM at 48 h after training. Considering the small and nonsignificant difference between the recovery of TB and PM muscles, the results suggest that bench press exercise may promote a similar stress on these muscles. Muscle Nerve 56: 963-967, 2017. © 2016 Wiley Periodicals, Inc.

EFFECT OF DIFFERENT LEVELS OF LOCALIZED MUSCLE FATIGUE ON KNEE POSITION SENSE

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William S. Gear

2011-12-01

Full Text Available There is little information available regarding how proprioceptive abilities decline as the amount of exertion increases during exercise. The purpose of this study was to determine the role of different levels of fatigue on knee joint position sense. A repeated measures design was used to examine changes in active joint reposition sense (AJRS prior to and following three levels of fatigue. Eighteen participants performed knee extension and flexion isokinetic exercise until torque output was 90%, 70%, or 50% of the peak hamstring torque for three consecutive repetitions. Active joint reposition sense at 15, 30, or 45 degrees was tested following the isokinetic exercise session. Following testing of the first independent measure, participants were given a 20 minute rest period. Testing procedures were repeated for two more exercise sessions following the other levels of fatigue. Testing of each AJRS test angle was conducted on three separate days with 48 hours between test days. Significant main effect for fatigue was indicated (p = 0.001. Pairwise comparisons indicated a significant difference between the pre-test and following 90% of peak hamstring torque (p = 0.02 and between the pre-test and following 50% of peak hamstring torque (p = 0.02. Fatigue has long been theorized to be a contributing factor in decreased proprioceptive acuity, and therefore a contributing factor to joint injury. The findings of the present study indicate that fatigue may have an effect on proprioception following mild and maximum fatigue.

Reliability, Validity, and Sensitivity of a Novel Smartphone-Based Eccentric Hamstring Strength Test in Professional Football Players.

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Lee, Justin W Y; Cai, Ming-Jing; Yung, Patrick S H; Chan, Kai-Ming

2018-05-01

To evaluate the test-retest reliability, sensitivity, and concurrent validity of a smartphone-based method for assessing eccentric hamstring strength among male professional football players. A total of 25 healthy male professional football players performed the Chinese University of Hong Kong (CUHK) Nordic break-point test, hamstring fatigue protocol, and isokinetic hamstring strength test. The CUHK Nordic break-point test is based on a Nordic hamstring exercise. The Nordic break-point angle was defined as the maximum point where the participant could no longer support the weight of his body against gravity. The criterion for the sensitivity test was the presprinting and postsprinting difference of the Nordic break-point angle with a hamstring fatigue protocol. The hamstring fatigue protocol consists of 12 repetitions of the 30-m sprint with 30-s recoveries between sprints. Hamstring peak torque of the isokinetic hamstring strength test was used as the criterion for validity. A high test-retest reliability (intraclass correlation coefficient = .94; 95% confidence interval, .82-.98) was found in the Nordic break-point angle measurements. The Nordic break-point angle significantly correlated with isokinetic hamstring peak torques at eccentric action of 30°/s (r = .88, r 2  = .77, P hamstring strength measures among male professional football players.

Combined effects of myofeedback and isokinetic training on hand ...

African Journals Online (AJOL)

Combined effects of myofeedback and isokinetic training on hand function in spastic hemiplegic children. ... Both groups received a designed physical therapy program with isokinetic training for the triceps brachii muscle for 60 min, in addition group B received myofeedback training. Results: The post treatment results ...

The effects of a repeated bout of eccentric exercise on indices of muscle damage and delayed onset muscle soreness.

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Paddon-Jones, D; Muthalib, M; Jenkins, D

2000-03-01

This study examined markers of muscle damage following a repeated bout of maximal isokinetic eccentric exercise performed prior to full recovery from a previous bout. Twenty non-resistance trained volunteers were randomly assigned to a control (CON, n=10) or experimental (EXP, n=10) group. Both groups performed 36 maximal isokinetic eccentric contractions of the elbow flexors of the non-dominant arm (ECC1). The EXP group repeated the same eccentric exercise bout two days later (ECC2). Total work and peak eccentric torque were recorded during each set of ECC1 and ECC2. Isometric torque, delayed onset muscle soreness (DOMS), flexed elbow angle and plasma creatine kinase (CK) activity were measured prior to and immediately following ECC1 and ECC2. at 24h intervals for 7 days following ECC1 and finally on day 11. In both groups, all dependent variables changed significantly during the 2 days following ECC1. A further acute post-exercise impairment in isometric torque (30 +/- 5%) and flexed elbow angle (20 +/- 4%) was observed following ECC2 (p0.05). These findings suggest that when maximal isokinetic eccentric exercise is repeated two days after experiencing of contraction-induced muscle damage, the recovery time course is not significantly altered.

Efeitos de diferentes intervalos de recuperação no desempenho muscular isocinético em idosos Effects of different rest intervals on isokinetic muscle performance among older adults

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C Ernesto

2009-02-01

Full Text Available OBJETIVO: Comparar os efeitos de diferentes intervalos de recuperação (IR entre séries de contração isocinética no desempenho muscular em idosos. MÉTODOS: Vinte idosos voluntários (66,9±3,9 anos, 76,1±13,4kg, 169±5,2cm foram submetidos a três sessões de exercício resistido isocinético unilateral da musculatura extensora do joelho com diferentes IR (1 minuto, 2 minutos, e 3 minutos na velocidade de 60°•s-1. Cada sessão consistia em três séries de 10 repetições durante as quais foram avaliados o pico de torque (PT, trabalho total (TT e índice de fadiga (IF. ANOVA fatorial para medidas repetidas, com a análise de Post hoc por Bonferroni, foi utilizada para identificar possíveis diferenças entre os IR. O nível de significância estatístico utilizado foi de p0,05. Apesar de ter sido observado menor desempenho muscular na 3ª série em todos os IR, maiores quedas no PT, TT e IF foram observadas quando adotado o IR de 1minuto (pOBJECTIVE: To compare the effects of different rest intervals (RI between sets of isokinetic contractions on muscle performance in older adults. METHODS: Twenty older participants (66.9±3.9 years; 76.1±13.4kg; 169±5.2cm underwent three sessions of unilateral isokinetic training for the knee extensor muscles, with different RI (1 minute, 2 minutes and 3 minutes at an angular velocity of 60°•s-1. Each session consisted of three sets of 10 repetitions, during which the peak torque (PT, total work (TW and fatigue index (FI were evaluated. Factorial ANOVA for repeated measurements, with Bonferroni post-hoc analysis, was used to identify possible differences between the RI. The statistical significance level was set at p0.05. Although muscle performance was lower during the third sets with all RI, the greatest decreases in PT, TW and FI occurred with the 1 minute RI (p<0.05. CONCLUSIONS: The results showed that the RI variable has an important influence on isokinetic muscle performance in older

Changes in Muscle Strength in U19 Soccer Players During an Annual Training Cycle

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Lehnert Michal

2014-10-01

Full Text Available The aim of the study was to investigate the seasonal variation in isokinetic strength of the knee flexors and extensors, and conventional (H/QCONV and functional (H/QFUNC hamstring to quadriceps strength ratios in highly trained adolescent soccer players. The players (n=11; age 17.8±0.3 were measured at the end of the competitive season (autumn, at the beginning and the end of pre-season (winter and during the sixth week of a new competitive season. Isokinetic peak torque (concentric and eccentric was measured at 60°•s-1 in a sitting position with the hip flexed at 100°. The testing range of motion was set from 10 - 90° of knee flexion. The players performed a set of five maximum repetitions for both the dominant and non-dominant leg. Statistically significant differences (p<0.001 between the four seasonal measurements were noted for peak torque of the dominant leg knee flexors in concentric muscle action only. A post hoc analysis revealed a statistically significant increase in peak torque from the 1st to the 4th measurement (p<0.001; d=0.692 and from the 2nd to the 4th (p<0.01; d=0.564. The differences in the changes of peak torque of the knee flexors and extensors depending on type of muscle action and tendencies found in the H/Q ratios throughout the annual training cycle indicate that strength assessment of the knee flexors and extensors and their balance throughout the annual training cycle could be beneficial for elite male adolescent soccer players both in terms of performance and risk of injury.

Muscle strength and soccer practice as major determinants of bone mineral density in adolescents

DEFF Research Database (Denmark)

Seabra, André; Marques, Elisa; Brito, João

2012-01-01

into soccer players (SG; n=117) and control subjects (CG; n=34). Peak torque of knee extensors (PTE) and flexors (PTF) was measured during isokinetic knee joint movement (90°/s) of the dominant and non-dominant lower limbs. BMD and BMC of the whole-body, lumbar spine, dominant/non-dominant lower limb were...

Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

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Morin, Jean-Benoît; Gimenez, Philippe; Edouard, Pascal; Arnal, Pierrick; Jiménez-Reyes, Pedro; Samozino, Pierre; Brughelli, Matt; Mendiguchia, Jurdan

2015-01-01

Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability. PMID:26733889

Sprint acceleration mechanics: the major role of hamstrings in horizontal force production

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Jean-Benoit eMORIN

2015-12-01

Full Text Available Recent literature supports the importance of horizontal ground reaction force (GRF production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG activity of the vastus lateralis, rectus femoris, biceps femoris and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024 between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.

Effect of eccentric isokinetic strengthening in the rehabilitation of patients with knee osteoarthritis: Isogo, a randomized trial

Science.gov (United States)

2014-01-01

Background Femorotibial knee osteoarthritis is associated with muscle weakness in the lower limbs, particularly in the quadriceps, which results in disease progression. The interest of having muscular strengthening as part of the therapeutic arsenal for the medical treatment of knee osteoarthritis is now well established. The functional disability induced by knee osteoarthritis manifests itself principally when walking, notably downhill, during which the muscles are called upon to contract eccentrically. We can therefore think that eccentric muscular strengthening could bring a functional benefit that is superior to concentric muscular strengthening. Methods/Design This is a prospective, randomized, bicenter, parallel-group, international study. Eighty patients aged from 40 to 75 years old, suffering from medical-stage knee osteoarthritis, will undertake 6 weeks of isokinetic muscular strengthening. Randomization determines the mode of muscular strengthening: either exclusively eccentric or exclusively concentric. The principal objective is to demonstrate the superiority of the improvement in the quadriceps isokinetic torque after isokinetic muscular strengthening by the eccentric mode compared to the concentric mode. The following parameters are also evaluated: the variations in the level of pain, the parameters of walking (maximum speed over 10 and 200 meters, analysis on a computerized Gaitrite™ treadmill), static equilibrium (on a FUSYO™ force platform), and the functional status of the patient using the Western Ontario and MacMaster Universities osteoarthritis index (WOMAC) questionnaire after the strengthening period and at 6 months. Discussion A better knowledge of the most effective mode of muscular strengthening is needed to optimize the functional benefits to the patients. In case of superiority in terms of efficacy of the eccentric mode, the latter could be given priority in the rehabilitation treatment of knee osteoarthritis patients. Trial

Análise da correlação entre pico de torque, desempenho funcional e frouxidão ligamentar em indivíduos normais e com reconstrução do ligamento cruzado anterior Functional performance and knee laxity in normal individuals and in individuals submitted to anterior cruciate ligament reconstruction

Directory of Open Access Journals (Sweden)

Rodrigo Antunes de Vasconcelos

2009-04-01

Full Text Available OBJETIVO: Analisar a correlação entre os déficits musculares dos extensores e flexores do joelho através do pico de torque isocinético com os testes de salto monopodal, frouxidão ligamentar pós-operatória e questionário de função em indivíduos normais e indivíduos submetidos à reconstrução do LCA com enxerto autólogo do tendão patelar e dos tendões flexores. MÉTODOS: Foram recrutados 60 indivíduos, formando três grupos: 20 indivíduos sem lesões no joelho (grupo GC e dois grupos de 20 indivíduos submetidos à reconstrução do LCA com tendão patelar (grupo GTP ou tendões flexores (grupo GTF. RESULTADOS: Os resultados demonstraram correlação significativa entre déficits no pico de torque e testes funcionais no torque extensor nos grupos GTF e GC. Não foram observadas correlações significativas entre frouxidão ligamentar pós-operatória e questionário de Lysholm com os testes de salto e déficits no pico de torque. Em relação à diferença entre os grupos, foi observado que o grupo GTP demonstrou maior déficit do torque extensor, menor pontuação no questionário de Lysholm e maior percentagem dos indivíduos com índice de simetria entre membros (ISM OBJECTIVES: The aim of this study was to analyze the correlation between deficits in the isokinetic peak torque of the knee extensors and flexors with hop tests, postoperative knee laxity and functional scores in normal and ACL- reconstructed subjects with patellar tendon and hamstring tendon autografts. METHODS: Sixty male subjects were enrolled and subdivided into three groups: Twenty subjects without knee injuries (GC group and two groups of 20 subjects submitted to ACL reconstruction with patellar tendon (GTP group and hamstrings autograft (GTF group. RESULTS: The results showed significant correlation between knee extensors peak torque and performance in the hop tests for GTF and GC groups. There are no significantly correlations between post op knee laxity

Comparison of knee flexion isokinetic deficits between seated and prone positions after ACL reconstruction with hamstrings graft: Implications for rehabilitation and return to sports decisions.

Science.gov (United States)

Koutras, Georgios; Bernard, Manfred; Terzidis, Ioannis P; Papadopoulos, Pericles; Georgoulis, Anastasios; Pappas, Evangelos

2016-07-01

Hamstrings grafts are commonly used in ACL reconstruction, however, the effect of graft harvesting on knee flexion strength has not been longitudinally evaluated in functional positions. We hypothesized that greater deficits in knee flexion strength exist in the prone compared to the seated position and these deficits remain as rehabilitation progresses. Case series. Forty-two consecutive patients who underwent ACL reconstruction with a hamstrings graft were followed prospectively for 9 months. Isokinetic knee flexion strength at a slow and a fast speed were collected at 3, 4, 6, and 9 months in two different positions: conventional (seated) and functional (0° of hip flexion). Peak torque knee flexion deficits were higher in the prone position compared to the seated position by an average of 6.5% at 60°/s and 9.1% at 180°/s (p<0.001). Measuring knee flexion strength in prone demonstrates higher deficits than in the conventional seated position. Most athletes would not be cleared to return to sports even at 9 months after surgery with this method. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Explosive sport training and torque kinetics in children.

Science.gov (United States)

Dotan, Raffy; Mitchell, Cameron J; Cohen, Rotem; Gabriel, David; Klentrou, Panagiota; Falk, Bareket

2013-07-01

A high rate of force development (RFD) is often more important than maximal force in daily and sports activities. In children, resistance training has been shown to increase maximal force. It is unclear whether, or to what extent, can children improve RFD and force kinetics. For this study, we compared strength and force kinetics of boy gymnasts with those of untrained boys and untrained men. Eight boy gymnasts (age, 9.5 ± 1.2 y), 20 untrained boys (age, 10.1 ± 1.3 y), and 20 untrained men (age, 22.9 ± 4.4 y) performed maximal, explosive, isometric elbow flexions (EF) and knee flexions (KF). Peak torque (maximal voluntary contraction (MVC)), elapsed times to 10%-100% MVC, peak rate of torque development (RTDpk), and other kinetics parameters were determined. When gymnasts were compared with untrained boys, size-normalized EF MVC was 11%-20% higher, RTDpk was 32% higher, and times to 30% and 80% MVC were 16% and 55% shorter, respectively (p kinetics parameters were similar. These findings highlight the specificity of gymnastics training, which markedly elevated the torque kinetics of young, prepubertal boys to adult levels, but only moderately affected peak torque. It is suggested that neurologic adaptations, such as enhanced firing and activation rates or increased type II motor-unit recruitment, as well as changes in musculotendinous stiffness, could explain these findings.

Muscle Fatigue during Intermittent Exercise in Individuals with Mental Retardation

Science.gov (United States)

Zafeiridis, Andreas; Giagazoglou, Paraskevi; Dipla, Konstantina; Salonikidis, Konstantinos; Karra, Chrisanthi; Kellis, Eleftherios

2010-01-01

This study examined fatigue profile during intermittent exercise in 10 men with mild to moderate mental retardation (MR) and 10 men without mental retardation (C). They performed 4 x 30 s maximal knee extensions and flexions with 1-min rest on an isokinetic dynamometer. Peak torque of flexors (PTFL) and extensors (PTEX), total work (TW), and…

Effect of a Short Time Concentric Versus Eccentric Training Program on Electromyography Activity and Peak Torque of Quadriceps

DEFF Research Database (Denmark)

Carvalho, Alberto; Caserotti, Paolo; Carvalho, C.

2014-01-01

The purpose of this study was to examine the effect of an 8-week concentric (CON) versus eccentric (ECC) isokinetic training program on the electromyography (EMG) signal amplitude of vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF). Also, the isometric (ISO) and dynamic maximum...

Modelling dental implant extraction by pullout and torque procedures.

Science.gov (United States)

Rittel, D; Dorogoy, A; Shemtov-Yona, K

2017-07-01

Dental implants extraction, achieved either by applying torque or pullout force, is used to estimate the bone-implant interfacial strength. A detailed description of the mechanical and physical aspects of the extraction process in the literature is still missing. This paper presents 3D nonlinear dynamic finite element simulations of a commercial implant extraction process from the mandible bone. Emphasis is put on the typical load-displacement and torque-angle relationships for various types of cortical and trabecular bone strengths. The simulations also study of the influence of the osseointegration level on those relationships. This is done by simulating implant extraction right after insertion when interfacial frictional contact exists between the implant and bone, and long after insertion, assuming that the implant is fully bonded to the bone. The model does not include a separate representation and model of the interfacial layer for which available data is limited. The obtained relationships show that the higher the strength of the trabecular bone the higher the peak extraction force, while for application of torque, it is the cortical bone which might dictate the peak torque value. Information on the relative strength contrast of the cortical and trabecular components, as well as the progressive nature of the damage evolution, can be revealed from the obtained relations. It is shown that full osseointegration might multiply the peak and average load values by a factor 3-12 although the calculated work of extraction varies only by a factor of 1.5. From a quantitative point of view, it is suggested that, as an alternative to reporting peak load or torque values, an average value derived from the extraction work be used to better characterize the bone-implant interfacial strength. Copyright © 2017 Elsevier Ltd. All rights reserved.

Predictors of chronic ankle instability: Analysis of peroneal reaction time, dynamic balance and isokinetic strength.

Science.gov (United States)

Sierra-Guzmán, Rafael; Jiménez, Fernando; Abián-Vicén, Javier

2018-05-01

Previous studies have reported the factors contributing to chronic ankle instability, which could lead to more effective treatments. However, factors such as the reflex response and ankle muscle strength have not been taken into account in previous investigations. Fifty recreational athletes with chronic ankle instability and 55 healthy controls were recruited. Peroneal reaction time in response to sudden inversion, isokinetic evertor muscle strength and dynamic balance with the Star Excursion Balance Test and the Biodex Stability System were measured. The relationship between the Cumberland Ankle Instability Tool score and performance on each test was assessed and a backward multiple linear regression analysis was conducted. Participants with chronic ankle instability showed prolonged peroneal reaction time, poor performance in the Biodex Stability System and decreased reach distance in the Star Excursion Balance Test. No significant differences were found in eversion and inversion peak torque. Moderate correlations were found between the Cumberland Ankle Instability Tool score and the peroneal reaction time and performance on the Star Excursion Balance Test. Peroneus brevis reaction time and the posteromedial and lateral directions of the Star Excursion Balance Test accounted for 36% of the variance in the Cumberland Ankle Instability Tool. Dynamic balance deficits and delayed peroneal reaction time are present in participants with chronic ankle instability. Peroneus brevis reaction time and the posteromedial and lateral directions of the Star Excursion Balance Test were the main contributing factors to the Cumberland Ankle Instability Tool score. No clear strength impairments were reported in unstable ankles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Isokinetic Testing in Evaluation Rehabilitation Outcome After ACL Reconstruction

OpenAIRE

Cvjetkovic, Dragana Dragicevic; Bijeljac, Sinisa; Palija, Stanislav; Talic, Goran; Radulovic, Tatjana Nozica; Kosanovic, Milkica Glogovac; Manojlovic, Slavko

2015-01-01

Introduction: Numerous rehab protocols have been used in rehabilitation after ACL reconstruction. Isokinetic testing is an objective way to evaluate dynamic stability of the knee joint that estimates the quality of rehabilitation outcome after ACL reconstruction. Our investigation goal was to show importance of isokinetic testing in evaluation thigh muscle strength in patients which underwent ACL reconstruction and rehabilitation protocol. Subjects and methods: In prospective study, we evalua...

Avaliação isocinética de 18 pacientes do sexo masculino submetidos à correção cirúrgica da luxação acromioclavicular aguda com seguimento mínimo de dois anos Isokinetic evaluation of eighteen male patients submitted to surgical corretion of acute acromioclavicular luxation with a minimum two-year follow-up

Directory of Open Access Journals (Sweden)

Flavio Almeida Salles

2002-06-01

Full Text Available Foram estudados 18 pacientes submetidos ao tratamento cirúrgico de luxação acromioclavicular aguda do grau III da classificação de ALLMAN-TOSSY, todos do sexo masculino com idade média de 36 anos, foram avaliados sob o ponto de vista isocinético com tempo de evolução variando de 24 até 127 meses. A avaliação isocinética foi realizada através de um dinamômetro computadorizado marca CYBEX® modelo 6000 na velocidade angular de 60º/segundo e demonstrou resultados significantes no movimento de abdução no plano neutro, com déficit no pico de torque do lado operado, quando comparado com o lado contra-lateral. Quando comparados os ombros com e sem subluxação, os com subluxação demonstraram défcit no trabalho total tanto na adução quanto na abdução no plano neutro.Eighteen male patients, mean age 36 years, submitted to surgical treatment of ALLMAN-TOSSY grade III acute acromioclavicular luxation were studied. They were isokinetically evaluated during an evolution period ranging from 24 to 127 months. The isokinetic evaluation was carried out with a Cybex® 6000 computerized dynamometer, at a 60º/s angular speed, showing significant results in vertical abduction, with a deficit in peak torque in the operated on shoulder as compared to the contralateral side. When the groups with and without subluxation were compared a deficit in total work was observed in the group with subluxation both in adduction and abduction.

Avaliação isocinética no joelho do atleta Isokinetic evaluation of athletes' knee

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Antonio Sérgio A.P. Terreri

2001-10-01

Full Text Available A avaliação isocinética tem sido usada nas últimas três décadas como método para se determinar o padrão funcional da força e do equilíbrio muscular. No nosso meio cresceu nos últimos 10 anos. É possível quantificar valores absolutos do torque, do trabalho e da potência de grupos musculares, bem como valores relativos, ou seja, da proporção agonista/antagonista de tais grupos. Outro recurso valioso consiste como método auxiliar na reabilitação das lesões esportivas. O exame é realizado com velocidade angular constante e predeterminada, seja lenta, intermediária e/ou rápida. O joelho é a articulação em que se observa maior aplicação e estudos isocinéticos. Na prática esportiva, temos por um lado a importância da proporção do equilíbrio muscular agonista/antagonista, ou seja, do equilíbrio flexor/extensor representado, respectivamente, pelos isquiotibiais/quadríceps. De outro, a comparação dos valores absolutos da função muscular entre os lados direito e esquerdo, quer seja para o quadríceps, ou para os isquiotibiais. Resultados alterados estão relacionados, geralmente, às lesões esportivas ou suas seqüelas. De interesse para o atleta e para a equipe multidisciplinar é poder dispor de um método de avaliação funcional muscular objetivo e seguro, que forneça dados confiáveis e reprodutíveis. Aspecto relevante reside no fato do resultado do teste isocinético poder ser útil nos critérios de retorno a atividade esportiva pós-lesão. Este artigo de revisão consiste em abordar alguns aspectos práticos da avaliação isocinética no joelho e sua utilização para os indivíduos que realizam atividade física.The isokinetic evaluation has been used in the last three decades as a method to determine both the strength functional pattern and the muscle balance. In our environment, this evaluation has been spread over the last 10 years. It is possible to quantify absolute values of torque, effort, and

Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

Science.gov (United States)

Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U

2017-06-01

To evaluate the effects of exercise velocity (60, 150, 240deg∙s -1 ) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO 2 ) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t 1/2 ) for oxygen uptake (V˙O 2 pulm), carbon dioxide output (V˙CO 2 pulm), and ventilation (V˙ E ). Significant differences of the t 1/2 values were identified between 60 and 150deg∙s -1 . Significant differences in the t 1/2 values were observed between V˙O 2 pulm and V˙CO 2 pulm and between V˙CO 2 pulm and V˙ E . The time to attain the first avDO 2 -peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O 2 pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O 2 pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.

Eccentric training for shoulder abductors improves pain, function and isokinetic performance in subjects with shoulder impingement syndrome: a case series Treino excêntrico para abdutores do ombro melhora dor, função e desempenho isocinético em sujeitos com síndrome do impacto: série de casos

Directory of Open Access Journals (Sweden)

Paula R. Camargo

2012-02-01

Full Text Available BACKGROUND: 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. OBJECTIVES: 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. METHODS: 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. RESULTS: DASH scores, peak torque, total work and acceleration time improved (pCONTEXTUALIZAÇÃO: Tratamentos conservadores têm sido propostos para pessoas com síndrome do impacto (SI do ombro, como fortalecimento do manguito rotador e dos músculos escapulares e alongamento dos tecidos moles do ombro. No entanto, são escassos os estudos que analisaram a eficácia do treinamento excêntrico no tratamento da SI. OBJETIVOS: Avaliar os efeitos do treinamento excêntrico para abdutores do ombro na dor, função e desempenho isocinético durante a abdução concêntrica e excêntrica do ombro em indivíduos com SI. MÉTODOS: Vinte indivíduos (sete

A laserterapia de baixa potência melhora o desempenho muscular mensurado por dinamometria isocinética em humanos Low-level laser therapy enhances muscular performance as measured by isokinetic dynamometry in humans

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Ernesto Cesar Pinto Leal Junior

2010-12-01

Full Text Available A fadiga muscular é uma nova área de pesquisa em laserterapia, com poucos estudos conduzidos. Embora a laserterapia de baixa potência (LBP previamente ao exercício tenha apresentado resultados positivos no retardo da fadiga musculoesquelética, ainda não foi estudada utilizando-se a dinamometria isocinética para mensurar desempenho e fadiga muscular. Este estudo tem o objetivo de avaliar os efeitos da LBP (655 nm, 50 mW, 2,4 J por ponto e 12 J de energia total sobre o desempenho e fadiga muscular do músculo tibial anterior, utilizando dinamometria isocinética (30 repetições de contração concêntrica em 14 indivíduos saudáveis sedentários do sexo masculino. Os voluntários foram avaliados ao efetuar 30 repetições isocinéticas de dorsiflexão de tornozelo à velocidade angular de 240°.seg-1. Os resultados mostram que, quando os voluntários foram tratados com LBP antes do exercício, os valores do pico de torque (30,91±5,86 N.m foram significativamente superiores, comparados a três medições anteriores sem a aplicação de LBP (24,92±7,45 N.m, pSkeletal muscle fatigue is a novel research area in laser therapy, there being few studies carried out. Though low-level laser therapy (LLLT applied prior to exercise has showed positive results in delaying skeletal muscle fatigue, no studies could be found that measured muscle performance and fatigue by means of isokinetic dynamometry. This clinical trial aims at assessing the effects of LLLT (655 nm, 50 mW and 12 J total energy delivered on anterior tibialis muscle performance and fatigue by means of isokinetic dynamometry (30 concentric-mode repetitions at 240º.sec-1 angular speed in 14 healthy male subjects. Results show that, when volunteers had been treated with LLLT prior to exercise, torque peak values (30.91±5.86 N.m were significantly higher than those of three previous measurements with no LLLT (24.92±7.45 N.m, p<0.001; 26.83±7.74 N.m, p<0.01; and 26.00±7.88 N.m, p<0

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.

Isokinetic Strength and Endurance Tests used Pre- and Post-Spaceflight: Test-Retest Reliability

Science.gov (United States)

Laughlin, Mitzi S.; Lee, Stuart M. C.; Loehr, James A.; Amonette, William E.

2009-01-01

To assess changes in muscular strength and endurance after microgravity exposure, NASA measures isokinetic strength and endurance across multiple sessions before and after long-duration space flight. Accurate interpretation of pre- and post-flight measures depends upon the reliability of each measure. The purpose of this study was to evaluate the test-retest reliability of the NASA International Space Station (ISS) isokinetic protocol. Twenty-four healthy subjects (12 M/12 F, 32.0 +/- 5.6 years) volunteered to participate. Isokinetic knee, ankle, and trunk flexion and extension strength as well as endurance of the knee flexors and extensors were measured using a Cybex NORM isokinetic dynamometer. The first weekly session was considered a familiarization session. Data were collected and analyzed for weeks 2-4. Repeated measures analysis of variance (alpha=0.05) was used to identify weekly differences in isokinetic measures. Test-retest reliability was evaluated by intraclass correlation coefficients (ICC) (3,1). No significant differences were found between weeks in any of the strength measures and the reliability of the strength measures were all considered excellent (ICC greater than 0.9), except for concentric ankle dorsi-flexion (ICC=0.67). Although a significant difference was noted in weekly endurance measures of knee extension (p less than 0.01), the reliability of endurance measure by week were considered excellent for knee flexion (ICC=0.97) and knee extension (ICC=0.96). Except for concentric ankle dorsi-flexion, the isokinetic strength and endurance measures are highly reliable when following the NASA ISS protocol. This protocol should allow accurate interpretation isokinetic data even with a small number of crew members.

Torque Split Strategy for Parallel Hybrid Electric Vehicles with an Integrated Starter Generator

OpenAIRE

Fu, Zhumu; Gao, Aiyun; Wang, Xiaohong; Song, Xiaona

2014-01-01

This paper presents a torque split strategy for parallel hybrid electric vehicles with an integrated starter generator (ISG-PHEV) by using fuzzy logic control. By combining the efficiency map and the optimum torque curve of the internal combustion engine (ICE) with the state of charge (SOC) of the batteries, the torque split strategy is designed, which manages the ICE within its peak efficiency region. Taking the quantified ICE torque, the quantified SOC of the batteries, and the quantified I...

Shoulder Rotator Muscle Dynamometry Characteristics: Side Asymmetry and Correlations with Ball-Throwing Speed in Adolescent Handball Players

Science.gov (United States)

Pontaga, Inese; Zidens, Janis

2014-01-01

The aim of the investigation was to: 1) compare shoulder external/internal rotator muscles’ peak torques and average power values and their ratios in the dominant and non-dominant arm; 2) determine correlations between shoulder rotator muscles’ peak torques, average power and ball-throwing speed in handball players. Fourteen 14 to 15-year-old male athletes with injury-free shoulders participated in the study (body height: 176 ± 7 cm, body mass 63 ± 9 kg). The tests were carried out by an isokinetic dynamometer system in the shoulder internal and external rotation movements at angular velocities of 60°/s, 90°/s and 240°/s during concentric contractions. The eccentric external– concentric internal rotator muscle contractions were performed at the velocity of 90°/s. The player threw a ball at maximal speed keeping both feet on the floor. The speed was recorded with reflected light rays. Training in handball does not cause significant side asymmetry in shoulder external/internal rotator muscle peak torques or the average power ratio. Positive correlations between isokinetic characteristics of the shoulder internal and external rotator muscles and ball-throwing speed were determined. The power produced by internal rotator muscles during concentric contractions after eccentric contractions of external rotator muscles was significantly greater in the dominant than in the non-dominant arm. Thus, it may be concluded that the shoulder eccentric external/concentric internal rotator muscle power ratio is significantly greater than this ratio in the concentric contractions of these muscles. PMID:25414738

Shoulder Rotator Muscle Dynamometry Characteristics: Side Asymmetry and Correlations with Ball-Throwing Speed in Adolescent Handball Players

Directory of Open Access Journals (Sweden)

Pontaga Inese

2014-10-01

Full Text Available The aim of the investigation was to: 1 compare shoulder external/internal rotator muscles’ peak torques and average power values and their ratios in the dominant and non-dominant arm; 2 determine correlations between shoulder rotator muscles’ peak torques, average power and ball-throwing speed in handball players. Fourteen 14 to 15- year-old male athletes with injury-free shoulders participated in the study (body height: 176 ± 7 cm, body mass 63 ± 9 kg. The tests were carried out by an isokinetic dynamometer system in the shoulder internal and external rotation movements at angular velocities of 60°/s, 90°/s and 240°/s during concentric contractions. The eccentric external- concentric internal rotator muscle contractions were performed at the velocity of 90°/s. The player threw a ball at maximal speed keeping both feet on the floor. The speed was recorded with reflected light rays. Training in handball does not cause significant side asymmetry in shoulder external/internal rotator muscle peak torques or the average power ratio. Positive correlations between isokinetic characteristics of the shoulder internal and external rotator muscles and ball-throwing speed were determined. The power produced by internal rotator muscles during concentric contractions after eccentric contractions of external rotator muscles was significantly greater in the dominant than in the non-dominant arm. Thus, it may be concluded that the shoulder eccentric external/concentric internal rotator muscle power ratio is significantly greater than this ratio in the concentric contractions of these muscles

Mechanical torque measurement in the proximal femur correlates to failure load and bone mineral density ex vivo

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Stefan Grote

2013-06-01

Full Text Available Knowledge of local bone quality is essential for surgeons to determine operation techniques. A device for intraoperative measurement of local bone quality has been developed by the AO-Research Foundation (DensiProbe®. We used this device to experimentally measure peak breakaway torque of trabecular bone in the proximal femur and correlated this with local bone mineral density (BMD and failure load. Bone mineral density of 160 cadaver femurs was measured by ex situ dual-energy X-ray absorptiometry. The failure load of all femurs was analyzed by side-impact analysis. Femur fractures were fixed and mechanical peak torque was measured with the DensiProbe® device. Correlation was calculated whereas correlation coefficient and significance was calculated by Fisher’s Z-transformation. Moreover, linear regression analysis was carried out. The unpaired Student’s t-test was used to assess the significance of differences. The Ward triangle region had the lowest BMD with 0.511 g/cm2 (±0.17 g/cm2, followed by the upper neck region with 0.546 g/cm2 (±0.16 g/cm2, trochanteric region with 0.685 g/cm2 (±0.19 g/cm2 and the femoral neck with 0.813 g/cm2 (±0.2 g/cm2. Peak torque of DensiProbe® in the femoral head was 3.48 Nm (±2.34 Nm. Load to failure was 4050.2 N (±1586.7 N. The highest correlation of peak torque measured by Densi Probe® and load to failure was found in the femoral neck (r=0.64, P<0.001. The overall correlation of mechanical peak torque with T-score was r=0.60 (P<0.001. A correlation was found between mechanical peak torque, load to failure of bone and BMD in vitro. Trabecular strength of bone and bone mineral density are different aspects of bone strength, but a correlation was found between them. Mechanical peak torque as measured may contribute additional information about bone strength, especially in the perioperative testing.

Resistive wall tearing mode generated finite net electromagnetic torque in a static plasma

International Nuclear Information System (INIS)

Hao, G. Z.; Wang, A. K.; Xu, M.; Qu, H. P.; Peng, X. D.; Wang, Z. H.; Xu, J. Q.; Qiu, X. M.; Liu, Y. Q.

2014-01-01

The MARS-F code [Y. Q. Liu et al., Phys. Plasmas 7, 3681 (2000)] is applied to numerically investigate the effect of the plasma pressure on the tearing mode stability as well as the tearing mode-induced electromagnetic torque, in the presence of a resistive wall. The tearing mode with a complex eigenvalue, resulted from the favorable averaged curvature effect [A. H. Glasser et al., Phys. Fluids 18, 875 (1975)], leads to a re-distribution of the electromagnetic torque with multiple peaking in the immediate vicinity of the resistive layer. The multiple peaking is often caused by the sound wave resonances. In the presence of a resistive wall surrounding the plasma, a rotating tearing mode can generate a finite net electromagnetic torque acting on the static plasma column. Meanwhile, an equal but opposite torque is generated in the resistive wall, thus conserving the total momentum of the whole plasma-wall system. The direction of the net torque on the plasma is always opposite to the real frequency of the mode, agreeing with the analytic result by Pustovitov [Nucl. Fusion 47, 1583 (2007)]. When the wall time is close to the oscillating time of the tearing mode, the finite net torque reaches its maximum. Without wall or with an ideal wall, no net torque on the static plasma is generated by the tearing mode. However, re-distribution of the torque density in the resistive layer still occurs

Comparisons in the Recovery Response From Resistance Exercise Between Young and Middle-Aged Men.

Science.gov (United States)

Gordon, Joseph A; Hoffman, Jay R; Arroyo, Eliott; Varanoske, Alyssa N; Coker, Nicholas A; Gepner, Yftach; Wells, Adam J; Stout, Jeffrey R; Fukuda, David H

2017-12-01

Gordon, JA III, Hoffman, JR, Arroyo, E, Varanoske, AN, Coker, NA, Gepner, Y, Wells, AJ, Stout, JR, and Fukuda, DH. Comparisons in the recovery response from resistance exercise between young and middle-aged men. J Strength Cond Res 31(12): 3454-3462, 2017-The purpose of this study was to compare the effects of a bout of high-volume isokinetic resistance exercise protocol (HVP) on lower-body strength and markers of inflammation and muscle damage during recovery between young and middle-aged adult men. Nineteen recreationally trained men were classified as either a young adult (YA: 21.8 ± 2.0 years; 90.7 ± 11.6 kg) or a middle-aged adult (MA: 47.0 ± 4.4 years; 96.0 ± 21.5 kg) group. The HVP consisted of 8 sets of 10 repetitions, with 1 minute of rest between each set, performed on an isokinetic dynamometer at 60°·s. Maximal voluntary isometric contractions and isokinetic peak torque (PKT) and average torque (AVGT) (measured at 240° and 60°·s, respectively) were assessed at baseline (BL), immediately post (IP), 120 minutes, 24, and 48 hours after HVP. Blood was obtained at BL, IP, 30, 60, 120 minute, 24, and 48 hours after HVP to assess muscle damage and inflammation. All performance data were analyzed using repeated measures analysis of covariance, whereas all inflammatory and muscle damage markers were analyzed using a 2-way (time × group) repeated measures analysis of variance. Results revealed no between-group differences for PKT, AVGT, or rate of torque development at 200 ms (RTD200). No between-group differences in myoglobin, creatine kinase, C-reactive protein, or interleukin-6 were observed. Although BL differences in muscle performance were observed between YA and MA, no between-group differences were noted in performance recovery measures from high-volume isokinetic exercise in recreationally trained men. These results also indicate that the inflammatory and muscle damage response from high-volume isokinetic exercise is similar between

Immediate effects of whole body vibration on patellar tendon properties and knee extension torque.

Science.gov (United States)

Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R

2016-03-01

Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length. Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling. The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°. The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.

Improvement of the Torque-Speed Performance and Drive Efficiency in an SRM Using an Optimal Torque Sharing Function

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Wei Ye

2018-05-01

Full Text Available In this paper, by evaluating the extreme value of the qth-power current, a torque sharing function (TSF family for reducing the torque ripples in the switched reluctance motor (SRM is proposed. The optimization criteria of the TSF has two secondary objectives, including the maximization of the torque-speed range and the minimization of copper loss. The evaluation indices in terms of the peak phase current, the rms (root mean square phase current, and the torque ripple factor are compared between the proposed TSF family and four conventional TSFs including linear, sinusoidal, exponential, and cubic TSFs. An optimization objective function that combines the maximum absolute value of the rate-of-change of the flux linkage (MAV-RCFL and the qth-power of current is proposed and a weighting factor is used to balance the influence of the two optimization objectives. An optimal TSF can be easily obtained by solving the optimization problem from the TSF family. The proposed TSF is validated by using simulations and experiments with a three-phase 6/4 SRM with 7.5 kW, 3000 rpm, and 270 V DC-link voltage. The dynamic simulation model is implemented in Matlab/Simulink. The results demonstrate the validity and superiority of the proposed control method; the optimal TSF provides better torque-speed performance, and a better reduction in copper loss and torque ripples at high speed, as compared to conventional TSFs.

Recovery Kinetics of Knee Flexor and Extensor Strength after a Football Match

Science.gov (United States)

Draganidis, Dimitrios; Chatzinikolaou, Athanasios; Avloniti, Alexandra; Barbero-Álvarez, José C.; Mohr, Magni; Malliou, Paraskevi; Gourgoulis, Vassilios; Deli, Chariklia K.; Douroudos, Ioannis I.; Margonis, Konstantinos; Gioftsidou, Asimenia; Fouris, Andreas D.; Jamurtas, Athanasios Z.; Koutedakis, Yiannis; Fatouros, Ioannis G.

2015-01-01

We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12h, 36h and 60h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12h, 36h and 60h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (Pfootball-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level. PMID:26043222

Effects of a whole body vibration training program on strength, power, and functional tests in the physically active elderly

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Renata Gonçalves da Silva

2009-04-01

Full Text Available The aim of this study was to investigate the effect of a whole body vibration training program on knee extensor isokinetic peak torque, average power, and functional tests in the physically active elderly. Forty-seven subjects, who participated in a training program for the elderly, were recruited. The subjects were divided into two groups: whole body vibration group (WBV (n=24, 70.7±5.8 years, 62.7±12.3 kg and 155.9±8.0 cm and control group (n=23. 70.0±5.7 years, 65.3±10.7 kg and 157.9±6.6 cm. The WBS group underwent whole body vibration exercise and their regular training program for 13 weeks, 2 times per week, whereas the control group performed the regular training program only. Whole body vibration training was not effective in increasing isokinetic peak torque, average power, or performance in the functional tests. On the other hand, the regular training program was effective in increasing elbow flexor strength endurance, distance covered in the 6-min walk test, and speed in the timed up and go test. The results suggest that vibration training is not effective in modifying functionality or muscle strength and power in the physically active elderly.

Efficacy of pre-exercise low-level laser therapy on isokinetic muscle performance in individuals with type 2 diabetes mellitus: study protocol for a randomized controlled trial.

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Gomes, Cid André Fidelis de Paula; Leal-Junior, Ernesto Cesar Pinto; Biasotto-Gonzalez, Daniela Aparecida; El-Hage, Yasmin; Politti, Fabiano; Gonzalez, Tabajara de Oliveira; Dibai-Filho, Almir Vieira; de Oliveira, Adriano Rodrigues; Frigero, Marcelo; Antonialli, Fernanda Colella; Vanin, Adriane Aver; de Tarso Camillo de Carvalho, Paulo

2014-04-09

Type 2 diabetes, also known non-insulin-dependent diabetes, is the most prevalent type of the disease and involves defects in the secretion and action of insulin. The aim of the proposed study is to evaluate the efficacy of pre-exercise low-level laser therapy (LLLT) on muscle performance of the quadriceps femoris in individuals with type 2 diabetes. A double-blind, randomized, controlled clinical trial will be carried out in two treatment phases. In the first phase, quadriceps muscle performance will be evaluated using an isokinetic dynamometer and the levels of creatine kinase and lactate dehydrogenase (biochemical markers of muscle damage) will be determined. The participants will then be allocated to four LLLT groups through a randomization process using opaque envelopes: Group A (4 Joules), Group B (6 Joules), Group C (8 Joules) and Group D (0 Joules; placebo). Following the administration of LLLT, the participants will be submitted to an isokinetic eccentric muscle fatigue protocol involving the quadriceps muscle bilaterally. Muscle performance and biochemical markers of muscle damage will be evaluated again immediately after as well as 24 and 48 hours after the experimental protocol. One week after the last evaluation the second phase will begin, during which Groups A, B and C will receive the LLLT protocol that achieved the best muscle performance in phase 1 for a period of 4 weeks. At the end of this period, muscle performance will be evaluated again. The protocol for this study is registered with the World Health Organization under Universal Trial Number U1111-1146-7109. The purpose of this randomized clinical trial is to evaluate the efficacy of pre-exercise LLLT on the performance of the quadriceps muscle (peak torque, total muscle work, maximum power and fatigue index - normalized by body mass) in individuals with DM-2. The study will support the practice of evidence-based to the use of LLLT in improving muscle performance in Individuals with DM-2

Characteristics of upper extremity's muscle strength in Turkish national wheelchair basketball players team.

Science.gov (United States)

Akınoğlu, Bihter; Kocahan, Tuğba

2017-02-01

The objective of this study was to reveal characteristics of muscle strength of upper extremities of wheelchair (WC) basketball players and to ensure more-specific training program preparation. Isokinetic muscle strength of 12 WC basketball players were assessed by ISOMED 2000 device. The assessment protocol was evaluated at 60°/sec velocity with 5 times repeated force and at 240°/sec with 15 times repeated force. This protocol was carried out individually for shoulder flexion-extension and wrist flexion-extension movements at the right and left extremities. The flexion/extension ratio was determined to be outside of the ratios accepted as normal for primarily shoulder joint and for wrist joint. The extension movement was stronger than flexion movement in the shoulders at both velocities and the flexion movement was stronger than ex-tension movement in the wrist. The repeat times where the peak torque occurred were 2-3 repeats at 60°/sec velocity during flexion and extension movements for the wrist and shoulders, and the peak torque occurred at an average of 5-6 repeats in the shoulders at 240°/sec velocity and it occurred at 3-4 repeats in the wrist. The angles where the peak torque of the shoulder flexion and extension occurred varied between 80°-115° at both velocities, and it varied between 5°-30° angles for the wrist. As this study revealed, determination of muscle strength characteristics of WC athletes and especially using objective isokinetic devices will guide the planning of the appropriate training and exercise programs and preventing sports injuries in long term.

The effect of sterilization and number of use on the accuracy of friction-style mechanical torque limiting devices for dental implants

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Ali Fayaz

2014-01-01

Full Text Available Background: Mechanical torque limiting devices (MTLDs are necessary tools to control a peak torque and achieving target values of screw component of dental implants. Due to probable effect of autoclaving and number of use on the accuracy of these devices, this study aimed to evaluate the effect of sterilization and number of use on the accuracy of friction-style mechanical torque limiting devices (F-S MTLDs in achieving their target torque values. Materials and Methods: Peak torque measurements of 15 new F-S MTLDs from three different manufacturers (Astra Tech, BioHorizons, Dr. Idhe were measured ten times before and after 100 steam sterilization using a digital torque gauge. To simulate the clinical situation of aging (number of use target torque application process was repeated 10 times after each sterilization cycle and the peak torque values were registered. Comparison of the mean differences with target torque in each cycle was performed using one sample t test. Considering the type of MTLDs as inter subject comparison, One-way repeated measure ANOVA was used to evaluate the absolute values of differences between devices of each manufacturer in each group (α = 0.05. Results: The results of this study in Dr. Idhe group showed that, mean of difference values significantly differed from the target torque (P = 0.002 until 75 cycles. In Astra Tech group, also mean of difference values with under estimation trend, showed a significant difference with the target torque (P < 0.001. Mean of difference values significantly differed from the target torque with under estimation trend during all the 100 cycles in BioHorizons group (P < 0.05. Conclusion: The torque output of each individual device stayed in 10% difference from target torque values before 100 sterilization cycles, but more than 10% difference from the target torque was seen in varying degrees during these consequent cycles.

Functional shoulder ratios with high velocities of shoulder internal rotation are most sensitive to determine shoulder rotation torque imbalance: a cross-sectional study with elite handball players and controls.

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Castro, Marcelo Peduzzi de; Fonseca, Pedro; Morais, Sara Tribuzi; Borgonovo-Santos, Márcio; Coelho, Eduardo Filipe Cruz; Ribeiro, Daniel Cury; Vilas-Boas, João Paulo

2017-12-04

The aim of the present study was to determine which approach to calculating shoulder ratios is the most sensitive for determining shoulder torque imbalance in handball players. Twenty-six participants (handball athletes, n = 13; healthy controls, n = 13) performed isokinetic concentric and eccentric shoulder internal rotation (IR) and external rotation (ER) assessment at 60, 180 and 300°/s. We used eight approaches to calculating shoulder ratios: four concentric (i.e. concentric ER torque divided by concentric IR torque), and four functional (i.e. eccentric ER torque divided by concentric IR torque) at the velocities of 60, 180 and 300°/s for both IR and ER, and combining 60°/s of ER and 300°/s of IR. A three factorial ANOVA (factors: shoulder ratios, upper limb sides, and groups) along with Tukey's post-hoc analysis, and effect sizes were calculated. The findings suggested the functional shoulder ratio combining 60°/s of ER and 300°/s of IR is the most sensitive to detect differences between upper limbs for handball players, and between players and controls for the dominant side. The functional shoulder ratio combining 60°/s of ER with 300°/s of IR seems to present advantages over the other approaches for identifying upper limb asymmetries and differences in shoulder torque balance related to throwing.

Pelvic rotation torque during fast-pitch softball hitting under three ball height conditions.

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Iino, Yoichi; Fukushima, Atsushi; Kojima, Takeji

2014-08-01

The purpose of this study was to investigate the relevance of hip joint angles to the production of the pelvic rotation torque in fast-pitch softball hitting and to examine the effect of ball height on this production. Thirteen advanced female softball players hit stationary balls at three different heights: high, middle, and low. The pelvic rotation torque, defined as the torque acting on the pelvis through the hip joints about the pelvic superior-inferior axis, was determined from the kinematic and force plate data using inverse dynamics. Irrespective of the ball heights, the rear hip extension, rear hip external rotation, front hip adduction, and front hip flexion torques contributed to the production of pelvic rotation torque. Although the contributions of the adduction and external rotation torques at each hip joint were significantly different among the ball heights, the contributions of the front and rear hip joint torques were similar among the three ball heights owing to cancelation of the two torque components. The timings of the peaks of the hip joint torque components were significantly different, suggesting that softball hitters may need to adjust the timings of the torque exertions fairly precisely to rotate the upper body effectively.

Neural and morphological adaptations of vastus lateralis and vastus medialis muscles to isokinetic eccentric training

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Rodrigo de Azevedo Franke

2014-09-01

Full Text Available Vastus lateralis (VL and vastus medialis (VM are frequently targeted in conditioning/rehabilitation programs due to their role in patellar stabilization during knee extension. This study assessed neural and muscular adaptations in these two muscles after an isokinetic eccentric training program. Twenty healthy men underwent a four-week control period followed by a 12-week period of isokinetic eccentric training. Ultrasound evaluations of VL and VM muscle thickness at rest and electromyographic evaluations during maximal isometric tests were used to assess the morphological and neural properties, respectively. No morphological and neural changes were found throughout the control period, whereas both muscles showed significant increases in thickness (VL = 6.9%; p .05 post-training. Isokinetic eccentric training produces neural and greater morphological adaptations in VM compared to VL, which shows that synergistic muscles respond differently to an eccentric isokinetic strength training program

Effects of the bilateral isokinetic strengthening training on functional parameters, gait, and the quality of life in patients with stroke.

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Büyükvural Şen, Sıdıka; Özbudak Demir, Sibel; Ekiz, Timur; Özgirgin, Neşe

2015-01-01

To evaluate the effects of the bilateral isokinetic strengthening training applied to knee and ankle muscles on balance, functional parameters, gait, and the quality of in stroke patients. Fifty patients (33 M, 17 F) with subacute-chronic stroke and 30 healthy subjects were included. Stroke patients were allocated into isokinetic and control groups. Conventional rehabilitation program was applied to all cases; additionally maximal concentric isokinetic strengthening training was applied to the knee-ankle muscles bilaterally to the isokinetic group 5 days a week for 3 weeks. Biodex System 3 Pro Multijoint System isokinetic dynamometer was used for isokinetic evaluation. The groups were assessed by Functional Independence Measure, Stroke Specific Quality of Life Scale, Timed 10-Meter Walk Test, Six-Minute Walk Test, Stair-Climbing Test, Timed up&go Test, Berg Balance Scale, and Rivermead Mobility Index. Compared with baseline, the isokinetic PT values of the knee and ankle on both sides significantly increased in all cases. PT change values were significantly higher in the isokinetic group than the control group (Pisokinetic group (Pisokinetic strengthening training in addition to conventional rehabilitation program after stroke seems to be effective on strengthening muscles on both sides, improving functional parameters, gait, balance and life quality.

Enthalpy-entropy compensation and the isokinetic temperature in ...

Indian Academy of Sciences (India)

Enthalpy-entropy compensation supposes that differences in activation enthalpy delta-H-++ for different reactions (or, typically inbiochemistry, the same reaction catalysed by enzymes obtained from different species) may be compensated for bydifferences in activation entropy delta-S-++. At the isokinetic temperature the ...

Isokinetic trunk muscle performance in pre-teens and teens with and without back pain.

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Bernard, J-C; Boudokhane, S; Pujol, A; Chaléat-Valayer, E; Le Blay, G; Deceuninck, J

2014-02-01

To assess with an isokinetic dynamometer the force and endurance of the spinal flexor and extensor muscles in pre-teens or teens aged 11 to 13 and 14 to 16 years with and without low back pain (LBP). The control group and the LBP group were homogeneous in terms of age, weight, height and Body Mass Index (BMI). Assessment was carried out with the isokinetic dynamometer Cybex Norm®. The spinal flexors and extensors were explored concentrically at speeds of 60°, 90° and 120°/sec. The parameters chosen were: maximal moment of force (MMF), mean power (MP), total work (TW), F/E ratios (between the flexors and the extensors for the aforesaid parameters). In the LBP groups, clinical information (pain, extensibility of the spinal and sub-pelvic muscles, sports practice) and sagittal radiological data were all measured. While no significant difference in isokinetic performance was found between asymptomatic and LBP children in the 11-to-13-year-old group, the isokinetic performances of the LBP children were influenced positively by BMI value, number of hours of physical activity and radiologic value of the lumbar lordosis. As regards these pre-teens, assessment with an isokinetic dynamometer does not highlight muscle characteristics that might explain LBP occurrence. As regards the 14-to-16-year-old group, muscle strength has been found to be correlated with age. LBP teens were showed to have weaker extensors and stronger flexors than the healthy teens. It is with regard to this age group that assessment with an isokinetic dynamometer clearly yields interesting results. Since we have yet to standardize our evaluation criteria (working speed, number of trials…), it is difficult to compare our results with those reported in the literature. This is a preliminary study involving a relatively low number of patients. That said, given the fact that numerous parameters are connected with the age and height of the subjects, assessment with an isokinetic dynamometer can be

Pneumatic tool torque reaction: reaction forces, displacement, muscle activity and discomfort in the hand-arm system.

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Kihlberg, S; Kjellberg, A; Lindbeck, L

1993-06-01

Reaction forces, hand-arm displacement, muscle activity and discomfort ratings were studied during the securing of threaded fasteners with three angle nutrunners with different shut-off mechanisms, but with the same spindle torque (72-74 Nm). The three tools were tested according to the method specified in ISO 6544. One of the tools had an almost instantaneous shut-off. Another had a more slowly declining torque curve. For the third tool the maximum torque was maintained for a while before shut-off. Twelve male subjects participated in the study. A force platform measured the reaction force between the subject and the floor. The option of the hand-arm system and the shoulder was measured with an optoelectronic measuring system. The muscle activity (EMG) in six muscles in the arm and shoulder was measured with surface electrodes. Significant differences in the arm movements and ground reaction forces were found between the three tools. The smallest values were found with the fast shut-off tool while the delayed shut-off tool caused the largest values. The EMG measures gave inconsistent response patterns. Discomfort ratings were highly correlated with the time for which the tool torque exceeded 90% of peak preset torque, but the time for which the tool torque exceeded 90% of peak calculated by the method specified in ISO 6544. Nutrunners with a shut-off mechanism that causes a slowly decreasing torque or a torque that is maintained for a while before shut-off should be avoided. If no substitutes are available, then a torque reaction bar should be mounted on the tool.

Pilot study: Effects of drinking hydrogen-rich water on muscle fatigue caused by acute exercise in elite athletes

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Aoki Kosuke

2012-07-01

Full Text Available Abstract Background Muscle contraction during short intervals of intense exercise causes oxidative stress, which can play a role in the development of overtraining symptoms, including increased fatigue, resulting in muscle microinjury or inflammation. Recently it has been said that hydrogen can function as antioxidant, so we investigated the effect of hydrogen-rich water (HW on oxidative stress and muscle fatigue in response to acute exercise. Methods Ten male soccer players aged 20.9 ± 1.3 years old were subjected to exercise tests and blood sampling. Each subject was examined twice in a crossover double-blind manner; they were given either HW or placebo water (PW for one week intervals. Subjects were requested to use a cycle ergometer at a 75 % maximal oxygen uptake (VO2 for 30 min, followed by measurement of peak torque and muscle activity throughout 100 repetitions of maximal isokinetic knee extension. Oxidative stress markers and creatine kinase in the peripheral blood were sequentially measured. Results Although acute exercise resulted in an increase in blood lactate levels in the subjects given PW, oral intake of HW prevented an elevation of blood lactate during heavy exercise. Peak torque of PW significantly decreased during maximal isokinetic knee extension, suggesting muscle fatigue, but peak torque of HW didn’t decrease at early phase. There was no significant change in blood oxidative injury markers (d-ROMs and BAP or creatine kinease after exercise. Conclusion Adequate hydration with hydrogen-rich water pre-exercise reduced blood lactate levels and improved exercise-induced decline of muscle function. Although further studies to elucidate the exact mechanisms and the benefits are needed to be confirmed in larger series of studies, these preliminary results may suggest that HW may be suitable hydration for athletes.

Carbohydrate vs protein supplementation for recovery of neuromuscular function following prolonged load carriage

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Fallowfield Joanne L

2010-01-01

Full Text Available Abstract Background This study examined the effect of carbohydrate and whey protein supplements on recovery of neuromuscular function after prolonged load carriage. Methods Ten male participants (body mass: 81.5 ± 10.5 kg, age: 28 ± 9 years, O2max: 55.0 ± 5.5 ml·kg-1·min-1 completed three treadmill walking tests (2 hr, 6.5 km·h-1, carrying a 25 kg backpack consuming 500 ml of either: (1 Placebo (flavoured water [PLA], (2 6.4% Carbohydrate Solution [CHO] or (3 7.0% Whey Protein Solution [PRO]. For three days after load carriage, participants consumed two 500 ml supplement boluses. Muscle performance was measured before and at 0, 24, 48 and 72 h after load carriage, during voluntary and electrically stimulated contractions. Results Isometric knee extension force decreased immediately after load carriage with no difference between conditions. During recovery, isometric force returned to pre-exercise values at 48 h for CHO and PRO but at 72 h for PLA. Voluntary activation decreased immediately after load carriage and returned to pre-exercise values at 24 h in all conditions (P = 0.086. During recovery, there were no differences between conditions for the change in isokinetic peak torque. Following reductions immediately after load carriage, knee extensor and flexor peak torque (60°·s-1 recovered to pre-exercise values at 72 h. Trunk extensor and flexor peak torque (15°·s-1 recovered to pre-exercise values at 24 h (P = 0.091 and 48 h (P = 0.177, respectively. Conclusion Recovery of neuromuscular function after prolonged load carriage is improved with either carbohydrate or whey protein supplementation for isometric contractions but not for isokinetic contractions.

An investigation of leg and trunk strength and reaction times of hard-style martial arts practitioners.

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Donovan, Oliver O; Cheung, Jeanette; Catley, Maria; McGregor, Alison H; Strutton, Paul H

2006-01-01

The purpose of this study was to investigate trunk and knee strength in practitioners of hard-style martial arts. An additional objective was to examine reaction times in these participants by measuring simple reaction times (SRT), choice reaction times (CRT) and movement times (MT). Thirteen high-level martial artists and twelve sedentary participants were tested under isokinetic and isometric conditions on an isokinetic dynamometer. Response and movement times were also measured in response to simple and choice auditory cues. Results indicated that the martial arts group generated a greater body-weight adjusted peak torque with both legs at all speeds during isokinetic extension and flexion, and in isometric extension but not flexion. In isokinetic and isometric trunk flexion and extension, martial artists tended to have higher peak torques than controls, but they were not significantly different (p > 0.05). During the SRT and CRT tasks the martial artists were no quicker in lifting their hand off a button in response to the stimulus [reaction time (RT)] but were significantly faster in moving to press another button [movement time (MT)]. In conclusion, the results reveal that training in a martial art increases the strength of both the flexors and extensors of the leg. Furthermore, they have faster movement times to auditory stimuli. These results are consistent with the physical aspects of the martial arts. Key PointsMartial artists undertaking hard-style martial arts have greater strength in their knee flexor and extensor muscles as tested under isokinetic testing. Under isometric testing conditions they have stronger knee extensors only.The trunk musculature is generally higher under both conditions of testing in the martial artists, although not significantly.The total reaction times of the martial artists to an auditory stimulus were significantly faster than the control participants. When analysed further it was revealed that the decrease in reaction time

Effect of stiffness and movement speed on selected dynamic torque characteristics of hydraulic-actuation joystick controls for heavy vehicles.

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Oliver, Michele; Rogers, Robert; Rickards, Jeremy; Tingley, Maureen; Biden, Edmund

2006-02-22

The purpose of this work was to quantify the effects of joystick stiffness and movement speed on the dynamic torque characteristics of hydraulic-actuation joystick controls, as found in off-road vehicles, as one of the initial steps towards the development of a joystick design protocol. Using a previously developed mathematical model in which a hydraulic-actuation joystick is assumed to rotate about two axes where the rotation origin is a universal joint, the dynamic torque characteristics incurred by an operator were predicted. Utilizing a laboratory mock-up of an excavator cab environment, three actuation torque characteristics (peak torque, angular impulse and deceleration at the hard endpoint) were quantified for nine unskilled joystick operators during the use of a commonly used North American hydraulic-actuation joystick. The six different experimental conditions included combinations of three joystick stiffnesses and two movement speeds. The highest instantaneous input torque over the course of the joystick movement (not including the hard endpoint) was evaluated using the peak torque value. Angular impulse provided an indication of the sustained exposure to force. The third indicator, deceleration at the hard endpoint, was included to provide a description of impact loading on the hand as the joystick came to a sudden stop. The most important result of this work is that the dynamic torque characteristics incurred during hydraulic-actuation joystick use are substantial. While the peak torque values were not very different between the fast and slow motion conditions, the high decelerations even for slow movements observed at maximum excursion of the joystick indicate that the dynamics do matter. On the basis of deceleration at the hard endpoint and peak torque, the joystick movements that require the highest values for a combination of torque variables are the side-to-side ones. This suggests that less stiff balance and return springs should be considered for

Torque Split Strategy for Parallel Hybrid Electric Vehicles with an Integrated Starter Generator

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Zhumu Fu

2014-01-01

Full Text Available This paper presents a torque split strategy for parallel hybrid electric vehicles with an integrated starter generator (ISG-PHEV by using fuzzy logic control. By combining the efficiency map and the optimum torque curve of the internal combustion engine (ICE with the state of charge (SOC of the batteries, the torque split strategy is designed, which manages the ICE within its peak efficiency region. Taking the quantified ICE torque, the quantified SOC of the batteries, and the quantified ICE speed as inputs, and regarding the output torque demanded on the ICE as an output, a fuzzy logic controller (FLC with relevant fuzzy rules has been developed to determine the optimal torque distribution among the ICE, the ISG, and the electric motor/generator (EMG effectively. The simulation results reveal that, compared with the conventional torque control strategy which uses rule-based controller (RBC in different driving cycles, the proposed FLC improves the fuel economy of the ISG-PHEV, increases the efficiency of the ICE, and maintains batteries SOC within its operation range more availably.

Isokinetic sampler; Amostrador isocinetico

Energy Technology Data Exchange (ETDEWEB)

Andrade, Luis Cesar C. de; Santos, Antonio Carlos dos [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Barrio, Lara B.A. del [AZ Armaturen do Brasil Ltda., Itatiba, SP (Brazil); Silva, Claudio B. da C. e; Silva, Ricardo R. da [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

2005-07-01

The Center of Research Leopoldo A. Miguez de Melo - CENPES - in association with AZ Armaturen Company do Brasil and TRANSPETRO developed and tested an Isokinetic sampler. This work presents the sampling principles and the results and performance of the tests realized in the 'Sitio de Testes de Atalaia' and in one of the terminals of bunker transfer of TRANSPETRO - 'Terminal Aquaviario da Baia de Guanabara'. In the 'Sitio de Testes' the products used were oil and water with BSW from 5% to 97% and in the terminal were tested samplings of bunker with ranges viscosities between (MF 180 to 380). (author)

ESTIMATION OF GRASPING TORQUE USING ROBUST REACTION TORQUE OBSERVER FOR ROBOTIC FORCEPS

OpenAIRE

塚本, 祐介

2015-01-01

Abstract— In this paper, the estimation of the grasping torque of robotic forceps without the use of a force/torque sensor is discussed. To estimate the grasping torque when the robotic forceps driven by a rotary motor with a reduction gear grasps an object, a novel robust reaction torque observer is proposed. In the case where a conventional reaction force/torque observer is applied, the estimated torque includes not only the grasping torque, namely the reaction torque, but also t...

Comparison Between a Reference Torque Standard Machine and a Deadweight Torque Standard Machine to BE Used in Torque Calibration

Science.gov (United States)

Meng, Feng; Zhang, Zhimin; Lin, Jing

The paper describes the reference torque standard machine with high accuracy and multifunction, developed by our institute, and introduces the structure and working principle of this machine. It has three main functions. The first function is the hydraulic torque wrench calibration function. The second function is torque multiply calibration function. The third function is reference torque standard machine function. We can calibrate the torque multipliers, hydraulic wrenches and transducers by this machine. A comparison experiment has been done between this machine and a deadweight torque standard machine. The consistency between the 30 kNm reference torque machine and the 2000 Nm dead-weight torque standard machine under the claimed uncertainties was verified.

Thoracic posture, shoulder muscle activation patterns and isokinetic ...

African Journals Online (AJOL)

Background. Shoulder injuries are the most severe injuries in rugby union players, accounting for almost 20% of injuries related to the sport and resulting in lost playing hours. Objective. To profile the thoracic posture, scapular muscle activation patterns and rotator cuff muscle isokinetic strength of semi-professional

Q-angle in patellofemoral pain: relationship with dynamic knee valgus, hip abductor torque, pain and function

Directory of Open Access Journals (Sweden)

Gabriel Peixoto Leão Almeida

2016-04-01

Full Text Available OBJECTIVE: To investigate the relationship between the q-angle and anterior knee pain severity, functional capacity, dynamic knee valgus and hip abductor torque in women with patellofemoral pain syndrome (PFPS. METHODS: This study included 22 women with PFPS. The q-angle was assessed using goniometry: the participants were positioned in dorsal decubitus with the knee and hip extended, and the hip and foot in neutral rotation. Anterior knee pain severity was assessed using a visual analog scale, and functional capacity was assessed using the anterior knee pain scale. Dynamic valgus was evaluated using the frontal plane projection angle (FPPA of the knee, which was recorded using a digital camera during step down, and hip abductor peak torque was recorded using a handheld dynamometer. RESULTS: The q-angle did not present any significant correlation with severity of knee pain (r = -0.29; p = 0.19, functional capacity (r = -0.08; p = 0.72, FPPA (r = -0.28; p = 0.19 or isometric peak torque of the abductor muscles (r = -0.21; p = 0.35. CONCLUSION: The q-angle did not present any relationship with pain intensity, functional capacity, FPPA, or hip abductor peak torque in the patients with PFPS.

THE EFFECTS OF ISOKINETIC KNEE STRENGTH ON THE PROMPTNESS OF SOCCER PLAYERS

OpenAIRE

Ali Kerim Yilmaz; Menderes Kabadayi; Muhammet Hakan Mayda; Murşit Ceyhun Birinci; Mustafa Özdal

2017-01-01

The purpose of this study is to examine the effects of isokinetic knee strength on promptness. 15 soccer players with an average age of 22,80±2,14 years and 15 controls with an average age of 21,60±1,40 years participated in the study. Body composition, isokinetic knee strength measurement at angular speeds of 60o, 180o, 240o and 10 m sprint test were conducted respectively in the study. General warm-up procedure was carried out on the groups before measurements. In statistical analyses, Shap...

Effect of axial tibial torque direction on ACL relative strain and strain rate in an in vitro simulated pivot landing.

Science.gov (United States)

Oh, Youkeun K; Kreinbrink, Jennifer L; Wojtys, Edward M; Ashton-Miller, James A

2012-04-01

Anterior cruciate ligament (ACL) injuries most frequently occur under the large loads associated with a unipedal jump landing involving a cutting or pivoting maneuver. We tested the hypotheses that internal tibial torque would increase the anteromedial (AM) bundle ACL relative strain and strain rate more than would the corresponding external tibial torque under the large impulsive loads associated with such landing maneuvers. Twelve cadaveric female knees [mean (SD) age: 65.0 (10.5) years] were tested. Pretensioned quadriceps, hamstring, and gastrocnemius muscle-tendon unit forces maintained an initial knee flexion angle of 15°. A compound impulsive test load (compression, flexion moment, and internal or external tibial torque) was applied to the distal tibia while recording the 3D knee loads and tibofemoral kinematics. AM-ACL relative strain was measured using a 3 mm DVRT. In this repeated measures experiment, the Wilcoxon signed-rank test was used to test the null hypotheses with p < 0.05 considered significant. The mean (±SD) peak AM-ACL relative strains were 5.4 ± 3.7% and 3.1 ± 2.8% under internal and external tibial torque, respectively. The corresponding mean (± SD) peak AM-ACL strain rates reached 254.4 ± 160.1%/s and 179.4 ± 109.9%/s, respectively. The hypotheses were supported in that the normalized mean peak AM-ACL relative strain and strain rate were 70 and 42% greater under internal than under external tibial torque, respectively (p = 0.023, p = 0.041). We conclude that internal tibial torque is a potent stressor of the ACL because it induces a considerably (70%) larger peak strain in the AM-ACL than does a corresponding external tibial torque. Copyright © 2011 Orthopaedic Research Society.

RELATIONSHIP BETWEEN ISOKINETIC KNEE STRENGTH AND JUMP CHARACTERISTICS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

Science.gov (United States)

Laudner, Kevin; Evans, Daniel; Wong, Regan; Allen, Aaron; Kirsch, Tom; Long, Brian; Meister, Keith

2015-06-01

Clinicians are often challenged when making return-to-play decisions following anterior cruciate ligament reconstruction (ACL-R). Isokinetic strength and jump performance testing are common tools used to make this decision. Unfortunately, vertical jump performance standards have not been clearly established and many clinicians do not have access to isokinetic testing equipment. To establish normative jump and strength characteristics in ACL-R patients cleared by an orthopedic physician to return-to-play and to determine if relationships exist between knee isokinetic strength measurements and jump characteristics described using an electronic jump map system. Descriptive laboratory study. Thirty-three ACL-R patients who had been cleared to return to athletic competition participated in this study. Twenty-six of these ACL-R participants were also matched to 26 asymptomatic athletes based on sex, limb, height, and mass to determine isokinetic strength and jump characteristic differences between groups. Jump tests consisted of single leg vertical, double leg vertical, and a 4-jump single leg vertical jump assessed using an electronic jump mat system. Independent t-tests were used to determine differences between groups and multiple regression analyses were used to identify any relationships between jump performance and knee strength (pjump capabilities and some bilateral knee strength deficiencies compared to the matched control group. The ACL-R group also showed several moderate-to-strong positive relationships for both knee extension and flexion strength with several jump performance characteristics, such as single and double leg vertical jump height. The current results indicate that ACL-R patients present with several knee strength and vertical jump differences compared to a matched control group at the time of return-to-play. Also, ACL-R patient's performance on an electronic jump mat system is strongly related to isokinetic knee strength measures. 2b.

Efeito do intervalo de recuperação entre séries de extensões isocinéticas de joelho em homens jovens destreinados Effect of recovery interval between sets of isokinetic knee extensions among untrained young men

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R Celes

2009-08-01

Full Text Available OBJETIVO: Avaliar o efeito de dois diferentes Intervalos de Recuperação (IR entre séries de extensões isocinéticas de joelho no Pico de Torque (PT e no Trabalho Total (TT em jovens destreinados. MÉTODOS: Dezoito homens (24,22±2,58 anos; 80,42±11,41 kg realizaram três séries de 10 extensões isocinéticas com o joelho direito a 60° e 180°/s. O IR entre as séries foram de 1 e 2 minutos, contrabalanceados entre os dois dias de teste, separados por, no mínimo, 48 horas. A taxa de trabalho-recuperação foi de 1:3 e 1:6 para 60°/s e 1:6 e 1:12 para 180°/s. Os voluntários não participavam de programas de treinamento resistido há pelo menos 6 meses. A análise estatística foi a ANOVA de medidas repetidas 2 x 3 [IR (1 e 2 minutos x série (1ª, 2ª e 3ª]. O nível de significância foi aOBJECTIVE: To assess the effect of two recovery intervals (RIs between sets of isokinetic knee extension exercises on peak torque (PT and total work (TW, among untrained young men. METHODS: Eighteen men (24.22±2.58 years; 80.42±11.41 kg performed three sets of ten isokinetic extensions of the right knee, at 60° and 180°/s. The RIs between the sets were one and two minutes long, spread over two test days separated by a minimum of 48 hours. The work-to-recovery ratio was 1:3 and 1:6 for 60°/s, and 1:6 and 1:12 for 180°/s. The subjects had not participated in any resistance training programs within the last six months. The statistical analysis consisted of 2 x 3 repeated-measures ANOVA [RI (one or two minutes x set (1st, 2nd or 3rd]. The significance level was a<0.05. RESULTS: Neither one minute nor two minutes RIs maintained the PT and TW throughout the three sets (p<0.05. However, at 60°/s, two minutes RIs enabled better PT and TW in the second and third sets than one minute RIs (p<0.05. At 180°/s, two minutes RIs were only better (p<0.05 than one minute RIs for TW in the third set. CONCLUSION: This study indicated that, during an isokinetic

Reliability of Concentric, Eccentric and Isometric Knee Extension and Flexion when using the REV9000 Isokinetic Dynamometer

DEFF Research Database (Denmark)

de Carvalho Froufe Andrade, Alberto César Pereira; Caserotti, Paolo; de Carvalho, Carlos Manuel Pereira

2013-01-01

The aim of this study was to assess the reliability of isokinetic and ISO knee extensor and flexor muscle strength when using the REV9000 (Technogym) isokinetic dynamometer. Moreover, the reliability of several strength imbalance indices and bilateral ratios were also examined. Twenty-four physic...

Reliability and relationships among handgrip strength, leg extensor strength and power, and balance in older men.

Science.gov (United States)

Jenkins, Nathaniel D M; Buckner, Samuel L; Bergstrom, Haley C; Cochrane, Kristen C; Goldsmith, Jacob A; Housh, Terry J; Johnson, Glen O; Schmidt, Richard J; Cramer, Joel T

2014-10-01

To quantify the reliability of isometric leg extension torque (LEMVC), rate of torque development (LERTD), isometric handgrip force (HGMVC) and RFD (HGRFD), isokinetic leg extension torque and power at 1.05rad·s(-1) and 3.14rad·s(-1); and explore relationships among strength, power, and balance in older men. Sixteen older men completed 3 isometric handgrips, 3 isometric leg extensions, and 3 isokinetic leg extensions at 1.05rad·s(-1) and 3.14rad·s(-1) during two visits. Intraclass correlation coefficients (ICCs), ICC confidence intervals (95% CI), coefficients of variation (CVs), and Pearson correlation coefficients were calculated. LERTD demonstrated no reliability. The CVs for LERTD and HGRFD were ≤23.26%. HGMVC wasn't related to leg extension torque or power, or balance (r=0.14-0.47; p>0.05). However, moderate to strong relationships were found among isokinetic leg extension torque at 1.05rad·s(-1) and 3.14rad·s(-1), leg extension mean power at 1.05rad·s(-1), and functional reach (r=0.51-0.95; p≤0.05). LERTD and HGRFD weren't reliable and shouldn't be used as outcome variables in older men. Handgrip strength may not be an appropriate surrogate for lower body strength, power, or balance. Instead, perhaps handgrip strength should only be used to describe upper body strength or functionality, which may compliment isokinetic assessments of lower body strength, which were reliable and related to balance. Copyright © 2014 Elsevier Inc. All rights reserved.

Hip joint torques during the golf swing of young and senior healthy males.

Science.gov (United States)

Foxworth, Judy L; Millar, Audrey L; Long, Benjamin L; Way, Michael; Vellucci, Matthew W; Vogler, Joshua D

2013-09-01

Descriptive, laboratory study. To compare the 3-D hip torques during a golf swing between young and senior healthy male amateur golfers. The secondary purpose was to compare the 3-D hip joint torques between the trail leg and lead leg. The generation of hip torques from the hip musculature is an important aspect of the golf swing. Golf is a very popular activity, and estimates of hip torques during the golf swing have not been reported. Twenty healthy male golfers were divided into a young group (mean ± SD age, 25.1 ± 3.1 years) and a senior group (age, 56.9 ± 4.7 years). All subjects completed 10 golf swings using their personal driver. A motion capture system and force plates were used to obtain kinematic and kinetic data. Inverse dynamic analyses were used to calculate 3-D hip joint torques of the trail and lead limbs. Two-way analyses of covariance (group by leg), with club-head velocity as a covariate, were used to compare peak hip torques between groups and limbs. Trail-limb hip external rotator torque was significantly greater in the younger group compared to the senior group, and greater in the trail leg versus the lead leg. When adjusting for club-head velocity, young and senior healthy male amateur golfers generated comparable hip torques during a golf swing, with the exception of the trail-limb hip external rotator torque. The largest hip torque found was the trail-limb hip extensor torque.

Magnetic Field and Torque Output of Packaged Hydraulic Torque Motor

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Liang Yan

2018-01-01

Full Text Available Hydraulic torque motors are one key component in electro-hydraulic servo valves that convert the electrical signal into mechanical motions. The systematic characteristics analysis of the hydraulic torque motor has not been found in the previous research, including the distribution of the electromagnetic field and torque output, and particularly the relationship between them. In addition, conventional studies of hydraulic torque motors generally assume an evenly distributed magnetic flux field and ignore the influence of special mechanical geometry in the air gaps, which may compromise the accuracy of analyzing the result and the high-precision motion control performance. Therefore, the objective of this study is to conduct a detailed analysis of the distribution of the magnetic field and torque output; the influence of limiting holes in the air gaps is considered to improve the accuracy of both numerical computation and analytical modeling. The structure and working principle of the torque motor are presented first. The magnetic field distribution in the air gaps and the magnetic saturation in the iron blocks are analyzed by using a numerical approach. Subsequently, the torque generation with respect to the current input and assembly errors is analyzed in detail. This shows that the influence of limiting holes on the magnetic field is consistent with that on torque generation. Following this, a novel modified equivalent magnetic circuit is proposed to formulate the torque output of the hydraulic torque motor analytically. The comparison among the modified equivalent magnetic circuit, the conventional modeling approach and the numerical computation is conducted, and it is found that the proposed method helps to improve the modeling accuracy by taking into account the effect of special geometry inside the air gaps.

Characteristics of myogenic response and ankle torque recovery after lengthening contraction-induced rat gastrocnemius injury

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Song Hongsun

2012-10-01

Full Text Available Abstract Background Although muscle dysfunction caused by unfamiliar lengthening contraction is one of most important issues in sports medicine, there is little known about the molecular events on regeneration process. The purpose of this study was to investigate the temporal and spatial expression patterns of myogenin, myoD, pax7, and myostatin after acute lengthening contraction (LC-induced injury in the rat hindlimb. Methods We employed our originally developed device with LC in rat gastrocnemius muscle (n = 24. Male Wistar rats were anesthetized with isoflurane (aspiration rate, 450 ml/min, concentration, 2.0%. The triceps surae muscle of the right hindlimb was then electrically stimulated with forced isokinetic dorsi-flexion (180°/sec and from 0 to 45°. Tissue contents of myoD, myogenin, pax7, myostatin were measured by western blotting and localizations of myoD and pax7 was measured by immunohistochemistry. After measuring isometric tetanic torque, a single bout of LC was performed in vivo. Results The torque was significantly decreased on days 2 and 5 as compared to the pre-treatment value, and recovered by day 7. The content of myoD and pax7 showed significant increases on day 2. Myogenin showed an increase from day 2 to 5. Myostatin on days 5 and 7 were significantly increased. Immunohistochemical analysis showed that myoD-positive/pax7-positive cells increased on day 2, suggesting that activated satellite cells play a role in the destruction and the early recovery phases. Conclusion We, thus, conclude that myogenic events associate with torque recovery after LC-induced injury.

Effects of the bilateral isokinetic strengthening training on functional parameters, gait, and the quality of life in patients with stroke

OpenAIRE

Büyükvural Şen, Sıdıka; Özbudak Demir, Sibel; Ekiz, Timur; Özgirgin, Neşe

2015-01-01

Objective: To evaluate the effects of the bilateral isokinetic strengthening training applied to knee and ankle muscles on balance, functional parameters, gait, and the quality of in stroke patients. Methods: Fifty patients (33 M, 17 F) with subacute-chronic stroke and 30 healthy subjects were included. Stroke patients were allocated into isokinetic and control groups. Conventional rehabilitation program was applied to all cases; additionally maximal concentric isokinetic strengthening traini...

A magneto-rheological fluid-based torque sensor for smart torque wrench application

Science.gov (United States)

Ahmadkhanlou, Farzad; Washington, Gregory N.

2013-04-01

In this paper, the authors have developed a new application where MR fluid is being used as a sensor. An MR-fluid based torque wrench has been developed with a rotary MR fluid-based damper. The desired set torque ranges from 1 to 6 N.m. Having continuously controllable yield strength, the MR fluid-based torque wrench presents a great advantage over the regular available torque wrenches in the market. This design is capable of providing continuous set toque from the lower limit to the upper limit while regular torque wrenches provide discrete set torques only at some limited points. This feature will be especially important in high fidelity systems where tightening torque is very critical and the tolerances are low.

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

Spin-orbit torque opposing the Oersted torque in ultrathin Co/Pt bilayers

Energy Technology Data Exchange (ETDEWEB)

Skinner, T. D., E-mail: tds32@cam.ac.uk; Irvine, A. C.; Heiss, D.; Kurebayashi, H.; Ferguson, A. J., E-mail: ajf1006@cam.ac.uk [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Wang, M.; Hindmarch, A. T.; Rushforth, A. W. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2014-02-10

Current-induced torques in ultrathin Co/Pt bilayers were investigated using an electrically driven ferromagnetic resonance technique. The angle dependence of the resonances, detected by a rectification effect as a voltage, was analysed to determine the symmetries and relative magnitudes of the spin-orbit torques. Both anti-damping (Slonczewski) and field-like torques were observed. As the ferromagnet thickness was reduced from 3 to 1 nm, the sign of the sum of the field-like torque and Oersted torque reversed. This observation is consistent with the emergence of a Rashba spin orbit torque in ultra-thin bilayers.

Influence of visual feedback on knee extensor isokinetic concentric ...

African Journals Online (AJOL)

Isokinetic normative data can be invaluable in identifying an individual's strengths and weaknesses, and thus lead to a more effective use of the individual's time to minimise or overcome his weaknesses while maintaining or improving existing strength. However, visual feedback (VF) may significantly affect the result of ...

Strength and hypertrophy responses to constant and decreasing rest intervals in trained men using creatine supplementation.

Science.gov (United States)

Souza-Junior, Tácito P; Willardson, Jeffrey M; Bloomer, Richard; Leite, Richard D; Fleck, Steven J; Oliveira, Paulo R; Simão, Roberto

2011-10-27

The purpose of the current study was to compare strength and hypertrophy responses to resistance training programs that instituted constant rest intervals (CI) and decreasing rest intervals (DI) between sets over the course of eight weeks by trained men who supplemented with creatine monohydrate (CR). Twenty-two recreationally trained men were randomly assigned to a CI group (n = 11; 22.3 ± 1 years; 77.7 ± 5.4 kg; 180 ± 2.2 cm) or a DI group (n = 11; 22 ± 2.5 years; 75.8 ± 4.9 kg; 178.8 ± 3.4 cm). Subjects in both groups supplemented with CR; the only difference between groups was the rest interval instituted between sets; the CI group used 2 minutes rest intervals between sets and exercises for the entire 8-weeks of training, while the DI group started with a 2 minute rest interval the first two weeks; after which the rest interval between sets was decreased 15 seconds per week (i.e. 2 minutes decreasing to 30 seconds between sets). Pre- and post-intervention maximal strength for the free weight back squat and bench press exercises and isokinetic peak torque were assessed for the knee extensors and flexors. Additionally, muscle cross-sectional area (CSA) of the right thigh and upper arm was measured using magnetic resonance imaging. Both groups demonstrated significant increases in back squat and bench press maximal strength, knee extensor and flexor isokinetic peak torque, and upper arm and right thigh CSA from pre- to post-training (p ≤ 0.0001); however, there were no significant differences between groups for any of these variables. The total volume for the bench press and back squat were significantly greater for CI group versus the DI group. We report that the combination of CR supplementation and resistance training can increase muscular strength, isokinetic peak torque, and muscle CSA, irrespective of the rest interval length between sets. Because the volume of training was greater for the CI group versus the DI group, yet strength gains were

Strength and hypertrophy responses to constant and decreasing rest intervals in trained men using creatine supplementation

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Fleck Steven J

2011-10-01

Full Text Available Abstract Background The purpose of the current study was to compare strength and hypertrophy responses to resistance training programs that instituted constant rest intervals (CI and decreasing rest intervals (DI between sets over the course of eight weeks by trained men who supplemented with creatine monohydrate (CR. Methods Twenty-two recreationally trained men were randomly assigned to a CI group (n = 11; 22.3 ± 1 years; 77.7 ± 5.4 kg; 180 ± 2.2 cm or a DI group (n = 11; 22 ± 2.5 years; 75.8 ± 4.9 kg; 178.8 ± 3.4 cm. Subjects in both groups supplemented with CR; the only difference between groups was the rest interval instituted between sets; the CI group used 2 minutes rest intervals between sets and exercises for the entire 8-weeks of training, while the DI group started with a 2 minute rest interval the first two weeks; after which the rest interval between sets was decreased 15 seconds per week (i.e. 2 minutes decreasing to 30 seconds between sets. Pre- and post-intervention maximal strength for the free weight back squat and bench press exercises and isokinetic peak torque were assessed for the knee extensors and flexors. Additionally, muscle cross-sectional area (CSA of the right thigh and upper arm was measured using magnetic resonance imaging. Results Both groups demonstrated significant increases in back squat and bench press maximal strength, knee extensor and flexor isokinetic peak torque, and upper arm and right thigh CSA from pre- to post-training (p ≤ 0.0001; however, there were no significant differences between groups for any of these variables. The total volume for the bench press and back squat were significantly greater for CI group versus the DI group. Conclusions We report that the combination of CR supplementation and resistance training can increase muscular strength, isokinetic peak torque, and muscle CSA, irrespective of the rest interval length between sets. Because the volume of training was greater for the

Influência do volume de alongamento estático dos músculos isquiotibiais nas variavéis isocinéticas Influence of static stretching volume in isokinetic variables of harmstrings

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Anselmo Grego Neto

2009-04-01

trabalho ao longo de algumas repetições não é.Stretching exercises are commonly prescribed before training sessions and competitions aiming at performance improvement and reduction of injury risk. However, many studies have shown that muscular torque production capacity may be reduced just after stretching. Therefore, the stretching duration necessary to produce these acute force deficits, as well as the physiological mechanisms responsible for them are relevant issues. The aim of this work was to investigate the acute effects of static stretching protocols with different durations on the isokinetic hamstrings performance. Thirty-six young male volunteers took part in this study and were evenly distributed in three groups: E1, E2 and C. All of them performed a systemic warm-up for five minutes and went through active range of motion (AROM of hip flexion and isokinetic assessment. The participants of groups E1 and E2 performed static stretching protocols of 180s (4 x 45s and 360s (8 x 45s respectively, and were evaluated again. The participants of group C (control remained at rest for a period of 270s and were evaluated again. The variables considered were AROM, peak torque, maximum work and total work. Both stretching protocols were able to produce increase in AROM; however, only the longest protocol produced deficits on peak torque and maximum work. Total work was not affected by any of the stretching protocols, though. Therefore, these results suggest that changes in muscular stiffness, that caused AROM gain, would not be responsible alone for the force deficits. Moreover, one can conclude that the maximum muscular strength depends on the stretching duration, but the muscular work along some repetitions of an exercise does not.

A Computational Model of Torque Generation: Neural, Contractile, Metabolic and Musculoskeletal Components

Science.gov (United States)

Callahan, Damien M.; Umberger, Brian R.; Kent-Braun, Jane A.

2013-01-01

The pathway of voluntary joint torque production includes motor neuron recruitment and rate-coding, sarcolemmal depolarization and calcium release by the sarcoplasmic reticulum, force generation by motor proteins within skeletal muscle, and force transmission by tendon across the joint. The direct source of energetic support for this process is ATP hydrolysis. It is possible to examine portions of this physiologic pathway using various in vivo and in vitro techniques, but an integrated view of the multiple processes that ultimately impact joint torque remains elusive. To address this gap, we present a comprehensive computational model of the combined neuromuscular and musculoskeletal systems that includes novel components related to intracellular bioenergetics function. Components representing excitatory drive, muscle activation, force generation, metabolic perturbations, and torque production during voluntary human ankle dorsiflexion were constructed, using a combination of experimentally-derived data and literature values. Simulation results were validated by comparison with torque and metabolic data obtained in vivo. The model successfully predicted peak and submaximal voluntary and electrically-elicited torque output, and accurately simulated the metabolic perturbations associated with voluntary contractions. This novel, comprehensive model could be used to better understand impact of global effectors such as age and disease on various components of the neuromuscular system, and ultimately, voluntary torque output. PMID:23405245

Limited Angle Torque Motors Having High Torque Density, Used in Accurate Drive Systems

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R. Obreja

2011-01-01

Full Text Available A torque motor is a special electric motor that is able to develop the highest possible torque in a certain volume. A torque motor usually has a pancake configuration, and is directly jointed to a drive system (without a gear box. A limited angle torque motor is a torque motor that has no rotary electromagnetic field — in certain papers it is referred to as a linear electromagnet. The main intention of the authors for this paper is to present a means for analyzing and designing a limited angle torque motor only through the finite element method. Users nowadays require very high-performance limited angle torque motors with high density torque. It is therefore necessary to develop the highest possible torque in a relatively small volume. A way to design such motors is by using numerical methods based on the finite element method.

Pilates improves lower limbs strength and postural control during quite standing in a child with hemiparetic cerebral palsy: A case report study.

Science.gov (United States)

Dos Santos, Adriana Neves; Serikawa, Simoni Sayuri; Rocha, Nelci Adriana Cicuto Ferreira

2016-08-01

To verify the effect of Pilates exercises in a child with cerebral palsy (CP) with mild functional impairment. We evaluated average peak torque of ankle and knee extensors/flexors using a Biodex System, using concentric active-assisted test. We also evaluated amplitude of anterior-posterior and of medial-lateral displacement of the CoP and area of oscillation during quite standing with a BERTEC platform. We applied Pilates exercises for eight weeks. Peak torque/body weight of ankle and knee extensors/flexors of both affected and unaffected limbs increased after Pilates. Also, all kinetic variables decreased after Pilates' intervention. After one-month follow-up, isokinetic variable values were higher while kinetic variable values were lower than baseline values. Pilates may be an important rehabilitation technique for children with CP that present mild deficits in motor structures and high functional level, especially when the aims are to improve muscle strength and postural control during quite standing.

Acute effects of short and long duration dynamic stretching protocols on muscle strength

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Christiano Francisco dos Santos

Full Text Available Objective Compare the acute effects of dynamic stretching protocols on the isokinetic performance of the quadriceps and hamstring muscles at two velocities in adult males.Methodology Included the participation of 14 males (21 ± 2.6 years; 178 ± 0.4 cm; 73.2 ± 20.9 kg were assessed using an isokinetic dynamometer before and after following a short or long-duration dynamic stretching protocol or a control protocol. The results were assessed by a two-way ANOVA and a Scheffé’s post hoc test at a 5% significance level.Results No difference was found in the variables assessed at 180°/s after LDDS. At 60°/s, LDDS reduced the power of the knee flexors. The control protocol reduced the power of the knee flexors and increased the power of the extensors. At 60°/s, the work of the knee flexors exhibited a reduction after LDDS. The control protocol resulted in a reduction in the work of the flexors. The peak torque angle exhibited a reduction in the extensors and flexors after LDDS and SDDS.Conclusion Dynamic stretching did not cause any change in the peak torque, which points to its possible use in activities involving velocity and muscle strength. The executing dynamic stretching before physical activities such as running and high-intensity sports might be beneficial by promoting increases in heart rate and in body temperature.

The influence of professional status on maximal and rapid isometric torque characteristics in elite soccer referees.

Science.gov (United States)

Palmer, Ty B; Hawkey, Matt J; Smith, Doug B; Thompson, Brennan J

2014-05-01

The purpose of this study was to examine the effectiveness of maximal and rapid isometric torque characteristics of the posterior muscles of the hip and thigh and lower-body power to discriminate between professional status in full-time and part-time professional soccer referees. Seven full-time (mean ± SE: age = 36 ± 2 years; mass = 82 ± 4 kg; and height = 179 ± 3 cm) and 9 part-time (age = 34 ± 2 years; mass = 84 ± 2 kg; and height = 181 ± 2 cm) professional soccer referees performed 2 isometric maximal voluntary contractions (MVCs) of the posterior muscles of the hip and thigh. Peak torque (PT) and absolute and relative rate of torque development (RTD) were calculated from a torque-time curve that was recorded during each MVC. Lower-body power output was assessed through a vertical jump test. Results indicated that the rapid torque characteristics were greater in the full-time compared with the part-time referees for absolute RTD (p = 0.011) and relative RTD at 1/2 (p = 0.022) and 2/3 (p = 0.033) of the normalized torque-time curve. However, no differences were observed for PT (p = 0.660) or peak power (Pmax, p = 0.149) between groups. These findings suggest that rapid torque characteristics of the posterior muscles of the hip and thigh may be sensitive and effective measures for discriminating between full-time and part-time professional soccer referees. Strength and conditioning coaches may use these findings to help identify professional soccer referees with high explosive strength-related capacities and possibly overall refereeing ability.

Combined effects of myofeedback and isokinetic training on hand ...

African Journals Online (AJOL)

Khaled A. Olama

2012-04-25

Apr 25, 2012 ... Subjects and methods: Thirty spastic hemiplegic children from both sexes ranging in age from ... physical therapy program with isokinetic training for the triceps brachii muscle for 60 min, in ... The Egyptian Journal of Medical Human Genetics ... than a third of all cases of CP, and the resulting impairments.

Isokinetic hamstring and quadriceps muscle strength profiles of elite ...

African Journals Online (AJOL)

Football players are at risk of lower limb injuries, specifically hamstring muscle strains and ACL injuries due to muscle imbalances. This was a descriptive study assessing the isokinetic hamstring and quadriceps muscle strength and endurance in 28 elite, male, South African football players. Muscle strength was tested at 60 ...

Self-oscillation in spin torque oscillator stabilized by field-like torque

International Nuclear Information System (INIS)

Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi

2014-01-01

The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation

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...... healthy matched subjects, using an isokinetic dynamometer (Cybex II). Maximum isometric strength at various knee extension angles (90 degrees, 60 degrees and 30 degrees degrees) was significantly (p less than 0.001) lower in the fibrositis group than in controls, a reduction of approximately 58......-66%. Maximum isokinetic strength at various knee extension velocities (30-240 degrees per second) was also significantly (p less than 0.01) lower in the fibrositis group than in controls, the reduction being approximately 41-51%. In conclusion, isometric and isokinetic muscle strength is found to be lower...

Accuracy of Replicating Static Torque and its Effect on Shooting Accuracy in Young Basketball Players

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Struzik Artur

2014-12-01

Full Text Available Purpose. Accurate shooting in basketball is a prerequisite for success. Coordination ability, one of the abilities that determine the repeatability of accurate shooting, is based on kinesthetic differentiation. The aim of the study was to evaluate the strength component of kinesthetic differentiation ability and determine its relationship with shooting accuracy. Methods. Peak muscle torque of the elbow extensors under static conditions was measured in 12 young basketball players. Participants then reproduced the same movement at a perceived magnitude of 25%, 50%, and 75% of static peak torque, with error scores calculated as a measure of kinesthetic differentiation. The results were compared with players’ field goal percentages calculated during game play in a regional championship. Results. No statistically significant relationships were found between the level of kinesthetic differentiation ability and field goal percentage. Additionally, no upper limb asymmetry was found in the sample. Conclusions. The relatively high levels of elbow static peak torque suggest the importance of upper limb strength in contemporary basketball. The lack of a statistically significant difference between the right and left limbs decreases the risk of suffering injury. It is likely that choosing other suitable tests would demonstrate the relationships between field goal percentage and kinesthetic differentiation ability.

Accuracy of dental torque wrenches.

Science.gov (United States)

Wood, James S; Marlow, Nicole M; Cayouette, Monica J

2015-01-01

The aim of this in vitro study was to compare the actual torque of 2 manual wrench systems to their stated (target) torque. New spring- (Nobel Biocare USA, LLC) and friction-style (Zimmer Dental, Inc.) manual dental torque wrenches, as well as spring torque wrenches that had undergone sterilization and clinical use, were tested. A calibrated torque gauge was used to compare actual torque to target torque values of 15 and 35 N/cm. Data were statistically analyzed via mixed-effects regression model with Bonferroni correction. At a target torque of 15 N/cm, the mean torque of new spring wrenches (13.97 N/cm; SE, 0.07 N/cm) was significantly different from that of used spring wrenches (14.94 N/cm; SE, 0.06 N/cm; P torques of new spring and new friction wrenches (14.10 N/cm; SE, 0.07 N/cm; P = 0.21) were not significantly different. For torque measurements calibrated at 35 N/cm, the mean torque of new spring wrenches (35.29 N/cm; SE, 0.10 N/cm) was significantly different (P torque could impact the clinical success of screw-retained dental implants. It is recommended that torque wrenches be checked regularly to ensure that they are performing to target values.

Power and Torque Characteristics of Diesel Engine Fuelled by Palm-Kernel Oil Biodiesel

Directory of Open Access Journals (Sweden)

Oguntola J. ALAMU

2009-07-01

Full Text Available Short-term engine performance tests were carried out on test diesel engine fuelled with Palm kernel oil (PKO biodiesel. The biodiesel fuel was produced through transesterification process using 100g PKO, 20.0% ethanol (wt%, 1.0% potassium hydroxide catalyst at 60°C reaction temperature and 90min. reaction time. The diesel engine was attached to a general electric dynamometer. Torque and power delivered by the engine were monitored throughout the 24-hour test duration at 1300, 1500, 1700, 2000, 2250 and 2500rpm. At all engine speeds tested, results showed that torque and power outputs for PKO biodiesel were generally lower than those for petroleum diesel. Also, Peak torque for PKO biodiesel occurred at a lower engine speed compared to diesel.

Neuromuscular and muscle-tendon system adaptations to isotonic and isokinetic eccentric exercise.

Science.gov (United States)

Guilhem, G; Cornu, C; Guével, A

2010-06-01

To present the properties of an eccentric contraction and compare neuromuscular and muscle-tendon system adaptations induced by isotonic and isokinetic eccentric trainings. An eccentric muscle contraction is characterized by the production of muscle force associated to a lengthening of the muscle-tendon system. This muscle solicitation can cause micro lesions followed by a regeneration process of the muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase muscle strength and muscle mass in athletes. Indeed, eccentric training stimulates muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise. The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies. 2010 Elsevier Masson SAS. All rights reserved.

Barbell deadlift training increases the rate of torque development and vertical jump performance in novices.

Science.gov (United States)

Thompson, Brennan J; Stock, Matt S; Shields, JoCarol E; Luera, Micheal J; Munayer, Ibrahim K; Mota, Jacob A; Carrillo, Elias C; Olinghouse, Kendra D

2015-01-01

The primary purpose of this study was to examine the effects of 10 weeks of barbell deadlift training on rapid torque characteristics of the knee extensors and flexors. A secondary aim was to analyze the relationships between training-induced changes in rapid torque and vertical jump performance. Fifty-four subjects (age, mean ± SD = 23 ± 3 years) were randomly assigned to a control (n = 20) or training group (n = 34). Subjects in the training group performed supervised deadlift training twice per week for 10 weeks. All subjects performed isometric strength testing of the knee extensors and flexors and vertical jumps before and after the intervention. Torque-time curves were used to calculate rate of torque development (RTD) values at peak and at 50 and 200 milliseconds from torque onset. Barbell deadlift training induced significant pre- to post-increases of 18.8-49.0% for all rapid torque variables (p torque capacities in both the knee extensors and flexors. Changes in rapid torque were associated with improvements in vertical jump height, suggesting a transfer of adaptations from deadlift training to an explosive, performance-based task. Professionals may use these findings when attempting to design effective, time-efficient resistance training programs to improve explosive strength capacities in novices.

Two-Finger Tightness: What Is It? Measuring Torque and Reproducibility in a Simulated Model.

Science.gov (United States)

Acker, William B; Tai, Bruce L; Belmont, Barry; Shih, Albert J; Irwin, Todd A; Holmes, James R

2016-05-01

Residents in training are often directed to insert screws using "two-finger tightness" to impart adequate torque but minimize the chance of a screw stripping in bone. This study seeks to quantify and describe two-finger tightness and to assess the variability of its application by residents in training. Cortical bone was simulated using a polyurethane foam block (30-pcf density) that was prepared with predrilled holes for tightening 3.5 × 14-mm long cortical screws and mounted to a custom-built apparatus on a load cell to capture torque data. Thirty-three residents in training, ranging from the first through fifth years of residency, along with 8 staff members, were directed to tighten 6 screws to two-finger tightness in the test block, and peak torque values were recorded. The participants were blinded to their torque values. Stripping torque (2.73 ± 0.56 N·m) was determined from 36 trials and served as a threshold for failed screw placement. The average torques varied substantially with regard to absolute torque values, thus poorly defining two-finger tightness. Junior residents less consistently reproduced torque compared with other groups (0.29 and 0.32, respectively). These data quantify absolute values of two-finger tightness but demonstrate considerable variability in absolute torque values, percentage of stripping torque, and ability to consistently reproduce given torque levels. Increased years in training are weakly correlated with reproducibility, but experience does not seem to affect absolute torque levels. These results question the usefulness of two-finger tightness as a teaching tool and highlight the need for improvement in resident motor skill training and development within a teaching curriculum. Torque measuring devices may be a useful simulation tools for this purpose.

Measurement of maximal isometric torque and muscle quality of the knee extensors and flexors in healthy 50- to 70-year-old women.

Science.gov (United States)

Francis, Peter; Toomey, Clodagh; Mc Cormack, William; Lyons, Mark; Jakeman, Philip

2017-07-01

Muscle quality is defined as strength per unit muscle mass. The aim of this study was to measure the maximal voluntary isometric torque of the knee extensor and flexor muscle groups in healthy older women and to develop an index of muscle quality based on the combined knee extensor and flexor torque per unit lean tissue mass (LTM) of the upper leg. One hundred and thirty-six healthy 50- to 70-year-old women completed an initial measurement of isometric peak torque of the knee extensors and flexors (Con-Trex MJ; CMV AG, Dubendorf, Switzerland) that was repeated 7 days later. Subsequently, 131 women returned for whole- and regional-body composition analysis (iDXA ™ ; GE Healthcare, Chalfont St Giles, Buckinghamshire, UK). Isometric peak torque demonstrated excellent within-assessment reliability for both the knee extensors and flexors (ICC range: 0·991-1·000). Test-retest reliability was lower (ICC range: 0·777-0·828) with an observed mean increase of 5% in peak torque [6·2 (17·2) N m] on the second day of assessment (Ptorque (-12·2%; P = 0·001) was double that of the relative, non-significant, median difference in upper leg LTM (-5·3%; P = 0·102) between those in the 5th and 6th decade. The majority of difference in peak isometric torque came from the knee extensors (15·1 N m, Ptorque normalized for upper leg LTM (muscle quality) was 8% lower between decades (P = 0·029). These findings suggest strength per unit tissue may provide a better indication of age-related differences in muscle quality prior to change in LTM. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

The Effects of Isokinetic Strength Training on Strength at Different Angular Velocities: a Pilot Study

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Tuğba Kocahan

2017-09-01

Conclusion: It was shown that angular velocity is important in isokinetic training, and that training at high angular velocities provides strength increases at lower angular velocities, but would not increase strength at angular velocities above the training level. For this reason, it is thought that in the preparation of an isokinetic strength training protocol, angular velocities need to be taken into account. For any athlete, the force at the angular velocity required in her/his sports branch needs to be considered.

[Progress in isokinetic technology in testing and training for assessment of muscle function].

Science.gov (United States)

Huang, Ting-Ting; Fan, Li-Hua; Gao, Dong; Xia, Qing; Zhang, Min

2013-02-01

Isokinetic technology in testing and training is the most advanced practical technique in the evaluation of muscle function. This method is a continuous dynamic test in the full range of the joint motion which has strong pertinence at the aspect of assessing muscle strength, and is an objective and quantitative method for reflecting each point's muscle strength in the range of the joint motion. This article reviews the key concepts, brief history of development and influencing factors of isokinetic technology in testing and training, introduces the progress in the field of rehabilitation medicine and sport science, etc., and discusses the future exploration in forensic science.

Analysis of the association between isokinetic knee strength with offensive and defensive jumping capacity in high-level female volleyball athletes.

Science.gov (United States)

Sattler, Tine; Sekulic, Damir; Esco, Michael R; Mahmutovic, Ifet; Hadzic, Vedran

2015-09-01

Isokinetic-knee-strength was hypothesized to be an important factor related to jumping performance. However, studies examining this relation among elite female athletes and sport-specific jumps are lacking. This investigation determined the influence of isokinetic-knee flexor/extensor strength measures on spike-jump (offensive) and block-jump (defensive) performance among high-level female volleyball players. Cross-sectional laboratory study. Eighty-two female volleyball athletes (age = 21.3 ± 3.8 years, height = 175.4 ± 6.76 cm, and weight = 68.29 ± 8.53 kg) volunteered to participate in this study. The studied variables included spike-jump and block-jump performance and a set of isokinetic tests to evaluate the eccentric and concentric strength capacities of the knee extensors (quadriceps - Q), and flexors (hamstring - H) for both legs. Both jumping tests showed high intra-session reliability (ICC of 0.87 and 0.95 for spike-jump and block-jump, respectively). The athletes were clustered into three achievement-groups based on their spike-jump and block-jump performances. For the block-jump, ANOVA identified significant differences between achievement-groups for all isokinetic variables except the Right-Q-Eccentric-Strength. When observed for spike-jump, achievement-groups differed significantly in all tests but Right-H-Concentric-Strength. Discriminant canonical analysis showed that the isokinetic-strength variables were more associated with block-jump then spike-jump-performance. The eccentric isokinetic measures were relatively less important determinants of block-jump than for the spike-jump performance. Data support the hypothesis of the importance of isokinetic strength measures for the expression of rapid muscular performance in volleyball. The results point to the necessity of the differential approach in sport training for defensive and offensive duties. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Results and Conclusions from the NASA Isokinetic Total Water Content Probe 2009 IRT Test

Science.gov (United States)

Reehorst, Andrew; Brinker, David

2010-01-01

The NASA Glenn Research Center has developed and tested a Total Water Content Isokinetic Sampling Probe. Since, by its nature, it is not sensitive to cloud water particle phase nor size, it is particularly attractive to support super-cooled large droplet and high ice water content aircraft icing studies. The instrument comprises the Sampling Probe, Sample Flow Control, and Water Vapor Measurement subsystems. Results and conclusions are presented from probe tests in the NASA Glenn Icing Research Tunnel (IRT) during January and February 2009. The use of reference probe heat and the control of air pressure in the water vapor measurement subsystem are discussed. Several run-time error sources were found to produce identifiable signatures that are presented and discussed. Some of the differences between measured Isokinetic Total Water Content Probe and IRT calibration seems to be caused by tunnel humidification and moisture/ice crystal blow around. Droplet size, airspeed, and liquid water content effects also appear to be present in the IRT calibration. Based upon test results, the authors provide recommendations for future Isokinetic Total Water Content Probe development.

Reliability of a device for the knee and ankle isometric and isokinetic strength testing in older adults.

Science.gov (United States)

Bergamin, Marco; Gobbo, Stefano; Bullo, Valentina; Vendramin, Barbara; Duregon, Federica; Frizziero, Antonio; Di Blasio, Andrea; Cugusi, Lucia; Zaccaria, Marco; Ermolao, Andrea

2017-01-01

Lower extremity muscle mass, strength, power, and physical performance are critical determinants of independent functioning in later life. Isokinetic dynamometers are becoming very common in assessing different features of muscle strength, in both research and clinical practice; however, reliability studies are still needed to support the extended use of those devices. The purpose of this study is to assess the test-retest reliability of knee and ankle isokinetic and isometric strength testing protocols in a sample of older healthy subjects, using a new and untested isokinetic multi-joint evaluation system. Sixteen male and fourteen female older adults (mean age 65.2 ± 4.6 years) were assessed in two testing sessions. Each participant performed a randomized testing procedure that includes different isometric and isokinetic tests for knee and ankle joints. All participants concluded the trial safety and no subject reported any discomfort throughout the overall assessment. Coefficients of correlation between measures were calculated showing moderate to strong effects among all test-retest assessments and paired-sample t test showed only one significant difference (pisometric strength provided reliable test-retest measures in healthy older adults. Ib.

Torque and Muscle Activation Impairment Along With Insulin Resistance Are Associated With Falls in Women With Fibromyalgia.

Science.gov (United States)

Góes, Suelen M; Stefanello, Joice M F; Homann, Diogo; Lodovico, Angélica; Hubley-Kozey, Cheryl L; Rodacki, André L F

2016-11-01

Góes, SM, Stefanello, JMF, Homann, D, Lodovico, A, Hubley-Kozey, CL, and Rodacki, ALF. Torque and muscle activation impairment along with insulin resistance are associated with falls in women with fibromyalgia. J Strength Cond Res 30(11): 3155-3164, 2016-Fibromyalgia (FM) is a chronic pain condition associated with reduced muscle strength, which can lead to functional incapacity and higher risk of falls. The purpose of the study was to compare maximal ankle joint torque, muscle activation, and metabolic changes between women with and without FM. In addition, the relationship between those aspects and retrospectively reported falls in women with FM was determined. Twenty-nine middle-aged women with FM and 30 controls were recruited. Fall history, pain intensity, and pain threshold were assessed. Plasma glucose levels and insulin resistance (IR) were determined. Peak torque and rate of torque development (RTD) were calculated, and muscle activation was assessed from maximum isometric voluntary ankle dorsiflexion and plantar flexion contractions. In addition, voluntary muscle activation failure of the anterior tibialis muscle during maximal dorsiflexion was calculated. When compared to controls, women with FM reported higher number of retrospectively reported falls, exhibited higher IR, showed reduced plantar flexion and dorsiflexion RTD, had lower plantar flexion peak torque, and demonstrated more antagonist coactivation and higher muscle activation failure (p ≤ 0.05). Higher muscle activation failure was explained by glucose level and pain intensity (adj R = 0.28; p ≤ 0.05). Reduced plantar flexion and dorsiflexion peak torque explained 80% of retrospectively reported falls variance; also, high antagonist coactivation (odds ratio [OR] = 1.6; p ≤ 0.05) and high IR (OR = 1.8; p ≤ 0.05) increased the chance of falls in the FM group. A combination of metabolic factors and muscle function increased the odds of retrospectively reporting a fall in FM. Both aspects

Assessment of muscular strength of knee flexors and extensors in individuals with and without osteoarthritis

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Sebastião Iberes Lopes Melo

2008-01-01

The aim of this study was to evaluate concentric and eccentric torque in individuals with and without knee osteoarthritis, and who did and did not practice physical activity. Specifically: to compare concentric and eccentric torque between groups; to compare the torques of dominant and non-dominant limbs within groups; to compare the concentric hamstrings/quadriceps ratio between groups. Fifty-eight elderly people participated, 32 with knee osteoarthritis and 26 with healthy knees. An isokinetic KinCom dynamometer was used for data collection. Concentric and eccentric peak torques of the quadriceps and hamstrings, normalized for body weight and concentric peak torque hamstring/quadriceps ratio of both sides were the study variables. At the Biomechanics Laboratory the following procedures were carried out: 1 identification form; 2 anthropometry; 3 warm-up and stretching; 4 positioning of the individual in a seated position with knee flexion of 90º and the back supported; 5 familiarization with the equipment; 6 acquisition of three reciprocal maximal concentric and eccentric contractions at 60º/s. Descriptive statistics and the Wilcoxon and the U Mann-Whitney tests were used to analyze data, to p≤0.05. The majority of concentric and eccentric torques in the control group were higher than those in the knee osteoarthritis group, with the exception of the concentric torque of non-dominant hamstrings and the eccentric quadriceps of the non-dominant limb. Although not significant, dominance seems to be determinant of increased torques in individuals without knee osteoarthritis. No statistically significant differences were detected between those who did and those who did not take part in physical activity. The results demonstrate that osteoarthritis provokes decrease of force especially in quadriceps.

Development of high torque belt CVT with torque converter; Torque converter tsuki daiyoryogata belt CVT no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Kurosawa, M; Fujikawa, T; Yoshida, K; Kobayahi, M [Nissan Motor Co. Ltd., Tokyo (Japan)

1997-10-01

Nissan has successfully developed a new belt CVT (Continuously Variable Transmission) with torque converter and has installed it 2L-class vehicle for the first time in the world. This paper describes about the technology of high torque transmission, the need of torque converter, the importance of electronic control and the introduce of driving mode. As the result the CVT has improved driving performance and fuel economy for current CVT and 4 speed automatic transmission. 13 figs., 2 tabs.

Posture and isokinetic shoulder strength in female water polo players

African Journals Online (AJOL)

Background: Being overhead athletes, water polo players can present with muscular imbalances of the shoulder, between the internal rotators (IR) and external rotators (ER), leading to changes in posture and an increased risk of injury. Objectives: To assess posture and isokinetic shoulder strength of female club-level ...

Isometric and isokinetic muscle strength in the upper extremity can be reliably measured in persons with chronic stroke.

Science.gov (United States)

Ekstrand, Elisabeth; Lexell, Jan; Brogårdh, Christina

2015-09-01

To evaluate the test-retest reliability of isometric and isokinetic muscle strength measurements in the upper extremity after stroke. A test-retest design. Forty-five persons with mild to moderate paresis in the upper extremity > 6 months post-stroke. Isometric arm strength (shoulder abduction, elbow flexion), isokinetic arm strength (elbow extension/flexion) and isometric grip strength were measured with electronic dynamometers. Reliability was evaluated with intra-class correlation coefficients (ICC), changes in the mean, standard error of measurements (SEM) and smallest real differences (SRD). Reliability was high (ICCs: 0.92-0.97). The absolute and relative (%) SEM ranged from 2.7 Nm (5.6%) to 3.0 Nm (9.4%) for isometric arm strength, 2.6 Nm (7.4%) to 2.9 Nm (12.6%) for isokinetic arm strength, and 22.3 N (7.6%) to 26.4 N (9.2%) for grip strength. The absolute and relative (%) SRD ranged from 7.5 Nm (15.5%) to 8.4 Nm (26.1%) for isometric arm strength, 7.1 Nm (20.6%) to 8.0 Nm (34.8%) for isokinetic arm strength, and 61.8 N (21.0%) to 73.3 N (25.6%) for grip strength. Muscle strength in the upper extremity can be reliably measured in persons with chronic stroke. Isometric measurements yield smaller measurement errors than isokinetic measurements and might be preferred, but the choice depends on the research question.

Using torque switch settings and spring pack characteristics to determine actuator output torques

International Nuclear Information System (INIS)

Black, B.R.

1992-01-01

Actuator output torque of motor operated valves is often a performance parameter of interest. It is not always possible to directly measure this torque. Torque spring pack deflection directly reflects actuator output torque and can be directly measured on most actuators. The torque spring pack may be removed from the actuator and tested to determine its unique force-deflection relationship. Or, a representative force-deflection relationship for the particular spring pack model may be available. With either relationship, measurements of torque spring pack deflection may then be correlated to corresponding forces. If the effective length of the moment arm within the actuator is known, actuator output torque can then be determined. The output torque is simply the product of the effective moment arm length and the spring pack force. This paper presents the reliability of this technique as indicated by testing. TU Electric is evaluating this technique for potential use in the future. Results presented in this paper should be considered preliminary. Applicability of these results may be limited to actuators and their components in a condition similar to those for which test data have been examined

Identification of cardiac repercussions after intense and prolonged concentric isokinetic exercise in young sedentary people.

Science.gov (United States)

Le Goff, Caroline; Kaux, Jean-François; Couffignal, Vincent; Coubard, Romain; Mélon, Pierre; Cavalier, Etienne; Croisier, Jean-Louis

2015-09-01

Cardiopathies are the world's leading cause of mortality and morbidity. Although rare, cardiovascular accidents can occur during intense and infrequent sporting activity, particularly among those who are unaware of their heart condition. The development of cardiospecific biochemical markers has led to a reconsideration of the role of biology in the diagnosis of cardiovascular illnesses. The aim of this study therefore was, through the use of cardiac biomarker assays, to highlight the impact of sustained physical effort in the form of intense and prolonged concentric isokinetic exercise and to research potential cardiovascular risks. Eighteen subjects participated in a maximal concentric isokinetic exercise involving 30 knee flexion-extensions for each leg. Five blood tests were taken to study the kinetics of the cardiac biomarkers. Haemodynamic parameters were measured continuously using a Portapres, and respiratory parameters were measured using a Sensormedics Vmax 29C. The results showed significant increases in the creatine kinase, myoglobin, homocysteine and haemoglobin cardiac markers. Evolutionary trends were also observed for the following biomarkers: NT-proBNP, myeloperoxydase and C-reactive protein. All the physiological parameters measured presented statistically significant changes. Isokinetic effort leads to the release of cardiac markers in the blood, but these do not exceed the reference values in healthy subjects. Maximal concentric isokinetic exercise does not, therefore, lead to an increased risk of cardiovascular pathologies. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Quadriceps rate of torque development and disability in individuals with anterior cruciate ligament reconstruction.

Science.gov (United States)

Davis, Hope C; Troy Blackburn, J; Ryan, Eric D; Luc-Harkey, Brittney A; Harkey, Matthew S; Padua, Darin A; Pietrosimone, Brian

2017-07-01

The purpose of this study was to determine associations between self-reported function (International Knee Documentation Committee Index), isometric quadriceps strength and rate of torque development in individuals with a unilateral anterior cruciate ligament reconstruction. Forty-one individuals [31% male, BMI mean 25 (SD 4) kg/m 2 , months post anterior cruciate ligament reconstruction mean 49 (SD 40)] completed the self-reported function and isometric quadriceps function testing. Rate of torque development was assessed at 0-100ms (early), 100-200ms (late) ms, and peak following the onset of contraction. Associations were examined between rate of torque development, strength, and self-reported function. Linear regression was used to determine the unique amount of variance explained by the combination of rate of torque development and strength. Higher rate of torque development 100-200ms is weakly associated with higher self-reported function in individuals with a unilateral anterior cruciate ligament reconstruction (r=0.274, p=0.091); however, rate of torque development 100-200ms does not predict a significant amount of variance in self-reported function after accounting for strength (ΔR 2 =0.003, P=0.721). Quadriceps strength has a greater influence on self-reported function compared to rate of torque development in individuals with an anterior cruciate ligament reconstruction with time from surgery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficient micromagnetic modelling of spin-transfer torque and spin-orbit torque

Science.gov (United States)

Abert, Claas; Bruckner, Florian; Vogler, Christoph; Suess, Dieter

2018-05-01

While the spin-diffusion model is considered one of the most complete and accurate tools for the description of spin transport and spin torque, its solution in the context of dynamical micromagnetic simulations is numerically expensive. We propose a procedure to retrieve the free parameters of a simple macro-spin like spin-torque model through the spin-diffusion model. In case of spin-transfer torque the simplified model complies with the model of Slonczewski. A similar model can be established for the description of spin-orbit torque. In both cases the spin-diffusion model enables the retrieval of free model parameters from the geometry and the material parameters of the system. Since these parameters usually have to be determined phenomenologically through experiments, the proposed method combines the strength of the diffusion model to resolve material parameters and geometry with the high performance of simple torque models.

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

Twenty women with primary fibromyalgia syndrome and 20 age matched healthy women were investigated. The subjects performed maximum voluntary isokinetic contractions of the right quadriceps in an isokinetic dynamometer. Maximum voluntary isometric contractions of the right quadriceps were performed...... 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...... submaximal force application in primary fibromyalgia syndrome....

Optical Torque Wrench: Angular Trapping, Rotation, and Torque Detection of Quartz Microparticles

Science.gov (United States)

La Porta, Arthur; Wang, Michelle D.

2004-05-01

We describe an apparatus that can measure the instantaneous angular displacement and torque applied to a quartz particle which is angularly trapped. Torque is measured by detecting the change in angular momentum of the transmitted trap beam. The rotational Brownian motion of the trapped particle and its power spectral density are used to determine the angular trap stiffness. The apparatus features a feedback control that clamps torque or other rotational quantities. The torque sensitivity demonstrated is ideal for the study of known biological molecular motors.

Butterfly valve torque prediction methodology

International Nuclear Information System (INIS)

Eldiwany, B.H.; Sharma, V.; Kalsi, M.S.; Wolfe, K.

1994-01-01

As part of the Motor-Operated Valve (MOV) Performance Prediction Program, the Electric Power Research Institute has sponsored the development of methodologies for predicting thrust and torque requirements of gate, globe, and butterfly MOVs. This paper presents the methodology that will be used by utilities to calculate the dynamic torque requirements for butterfly valves. The total dynamic torque at any disc position is the sum of the hydrodynamic torque, bearing torque (which is induced by the hydrodynamic force), as well as other small torque components (such as packing torque). The hydrodynamic torque on the valve disc, caused by the fluid flow through the valve, depends on the disc angle, flow velocity, upstream flow disturbances, disc shape, and the disc aspect ratio. The butterfly valve model provides sets of nondimensional flow and torque coefficients that can be used to predict flow rate and hydrodynamic torque throughout the disc stroke and to calculate the required actuation torque and the maximum transmitted torque throughout the opening and closing stroke. The scope of the model includes symmetric and nonsymmetric discs of different shapes and aspects ratios in compressible and incompressible fluid applications under both choked and nonchoked flow conditions. The model features were validated against test data from a comprehensive flowloop and in situ test program. These tests were designed to systematically address the effect of the following parameters on the required torque: valve size, disc shapes and disc aspect ratios, upstream elbow orientation and its proximity, and flow conditions. The applicability of the nondimensional coefficients to valves of different sizes was validated by performing tests on 42-in. valve and a precisely scaled 6-in. model. The butterfly valve model torque predictions were found to bound test data from the flow-loop and in situ testing, as shown in the examples provided in this paper

Evoked EMG versus Muscle Torque during Fatiguing Functional Electrical Stimulation-Evoked Muscle Contractions and Short-Term Recovery in Individuals with Spinal Cord Injury

Science.gov (United States)

Estigoni, Eduardo H.; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M.; Davis, Glen M.

2014-01-01

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery. PMID:25479324

Shoulder rotator isokinetic strength profile in young swimmers. DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n5p545

Directory of Open Access Journals (Sweden)

Pablo Tomas-Carus

2012-09-01

Full Text Available Considering that some studies suggest that shoulder rotators muscle imbal­ances are related to joint pain and injury, and that there are no normative data for young swimmers, the aim of this study was: i to describe the muscle balance, fatigue and isokinetic strength profile of the shoulder rotators in young swimmers; ii to compare the results between swimmers and a group of young non-practitioners; iii to contribute to the acquisition of normative data of unilateral ratios of shoulder rotators. We evaluated the shoulder rotators concentric strength and unilateral ratios (ratio between torque of external and internal rotators of 60 swimmers (age: 14.55 ± 0.5 years old; body mass: 61.16 ± 7.08 kg and 60 non-practitioners (age: 14.62 ± 0.49 years old; body mass: 60.22 ± 10.01 kg. The evaluation was performed in the sitting position (90° abduction and elbow flexion at 60º.s-1 and 180º.s-1 angular speeds using an isokinetic dynamometer (Biodex System 3. The results of the fatigue ratios revealed no differences between the groups. Swimmers showed unilateral ratios of 73.39 ± 17.26% in the dominant limb (DL and 77.89 ± 15,23% in the non-dominant limb (NDL for assessments at 60º.s-1. At 180º.s-1, ratios were 74.77± 13.99% for DL and 70.11 ± 14.57% for NDL. Swimmers presented greater muscle imbalance, and differed from non-practitioners in the ability to produce power with the internal rotators, which was significantly higher in the former group.

Decoupled Speed and Torque Control of IPMSM Drives Using a Novel Load Torque Estimator

Directory of Open Access Journals (Sweden)

ZAKY, M.

2017-08-01

Full Text Available This paper proposes decoupled speed and torque control of interior permanent magnet synchronous motor (IPMSM drives using a novel load torque estimator (LTE. The proposed LTE is applied for computing a load torque and yielding a feed-forward value in the speed controller to separate the torque control from the speed control. Indirect flux weakening using direct current component is obtained for high speed operation of the IPMSM drive, and its value for maximum torque per ampere (MTPA control in constant torque region is also used. LTE uses values of direct and quadrature currents to improve the behavior of the speed controller under the reference tracking and torque disturbances. The complete IPMSM drive by Matlab/Simulink is built. The effectiveness of the proposed control scheme using an experimental setup of the complete drive system implemented on a DSP-DS1102 control board is confirmed. Extensive results over a wide speed range are verified. The efficacy of the proposed method is confirmed in comparison to a conventional PI controller under both the reference speed tracking and load torque disturbance.

The Potential Risk Factors Relevant to Lateral Epicondylitis by Wrist Coupling Posture.

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Su-Ya Lee

Full Text Available The use of awkward wrist postures and unskilled techniques might induce lateral epicondylitis. This study thus investigated the effects of wrist deviation combined with extension and movement velocity on the dynamic performances of the wrist muscles during the coupling posture via a custom-made bi-planar isokinetic dynamometer. Thirty subjects were recruited to perform the isokinetic testing. We measured the muscle strengths and activities for the wrist extensors and flexors during concentric and eccentric contractions at three movement velocities, 30°s-1, 90°s-1, and 180°s-1, combined with three wrist postures, neutral position (NP, radial deviation (RD, and ulnar deviation (UD. The root mean square (RMS of the electromyographic signal in the extensor digitorum communis (EDC, normalized peak torque of extensors, and ratio of normalized peak torque between wrist extensors and flexors, were all greater in the NP than RD and UD in both contractions. The ratio of RMS between EDC and flexor digitorum superficialis (FDS had a significantly greater value in RD than UD during the concentric contraction. The EDC showed significantly higher activity at the fast velocity in both contractions. Nevertheless, a significantly higher RMS of the electromyographic signal between EDC and FDS and the ratio of strength between wrist extensors and flexors were found at slow velocity in both contractions. The wrist deviation combined with extension and movement velocity of the wrist joint should thus be considered as influential factors which might alter the dynamic performances, and may result in further injury of the elbow joint.

The effects of knee extensor eccentric training on functional tests in healthy subjects Os efeitos do treino isocinético excêntrico dos extensores do joelho nos testes funcionais em sujeitos saudáveis

Directory of Open Access Journals (Sweden)

Heleodório H. Santos

2010-08-01

Full Text Available BACKGROUND: It is well known that eccentric training increases muscle strength and promotes greater neural activation, and therefore has been used in the recovery of knee extensors. The hypothesis of this study was that there would be a strong correlation between knee extensor torque and functional tests. OBJECTIVES: To investigate the relationship between knee extensor peak torque and functional tests of agility (runs and propulsion (hop for distance after short-term isokinetic eccentric training. METHODS: Twenty healthy and active male undergraduate students (age 22.5±2.1 years; height 1.72±0.10 m; weight 67.8±9.5 kg; body mass index: 22.5±2.0 kg/m², with no abnormalities or history of injury of the limbs, performed an isokinetic assessment of the knee extensors and flexors and also functional tests before and after isokinetic training, which consisted of 3 sets of 10 MVECs at 30º/s, with 3 minutes of rest between sets, twice a week for 6 weeks. RESULTS: The eccentric training increased the extensor peak torque (16, 27 and 17%; PCONTEXTUALIZAÇÃO: Sabe-se que o treino excêntrico aumenta a força muscular, promovendo uma maior ativação neural e, portanto, tem sido usado na recuperação do torque extensor. A hipótese deste estudo foi a de que possa existir uma forte correlação entre o torque extensor do joelho e os testes funcionais. OBJETIVOS: Correlacionar o torque extensor do joelho com os testes funcionais de agilidade (corridas e impulsão (saltos em distância após o treino isocinético excêntrico de curta duração. MÉTODOS: Vinte homens universitários, ativos e saudáveis (22,5±2,1 anos; 1,72±0,10 m; 67,8±9,5 kg; IMC 22,5±2,0 kg/m², sem reportar anormalidades ou história de lesão no membro inferior, realizaram avaliação isocinética do torque extensor e flexor do joelho e testes funcionais antes e depois do treino isocinético que consistiu em três séries de 10 CEVM a 30º/s, com 3 minutos de repouso entre as

Game programmer's guide to Torque under the hood of the Torque game engine

CERN Document Server

Maurina , Edward F

2006-01-01

game programmer working with the Torque game engine must have ""The Game Programmer's Guide To Torque"": it teaches everything needed to design your own game, using experiences of game makers and industry veterans well versed in Torque technology. A Torque Game engine demo is included on an accompanying cd while step-by-step examples tell how to use it. Its focus on all the basics makes for an exceptional coverage for all levels of game programmer. -Bookwatch, August 2006

Torque sensor

Science.gov (United States)

Fgeppert, E.

1984-09-01

Mechanical means for sensing turning torque generated by the load forces in a rotary drive system is described. The sensing means is designed to operate with minimal effect on normal operation of the drive system. The invention can be employed in various drive systems, e.g., automotive engine-transmission power plants, electric motor-operated tools, and metal cutting machines. In such drive systems, the torque-sensing feature may be useful for actuation of various control devices, such as electric switches, mechanical clutches, brake actuators, fluid control valves, or audible alarms. The torque-sensing function can be used for safety overload relief, motor de-energization, engine fuel control transmission clutch actuation, remote alarm signal, tool breakage signal, etc.

Correlation between Initial BIC and the Insertion Torque/Depth Integral Recorded with an Instantaneous Torque-Measuring Implant Motor: An in vivo Study.

Science.gov (United States)

Capparé, Paolo; Vinci, Raffaele; Di Stefano, Danilo Alessio; Traini, Tonino; Pantaleo, Giuseppe; Gherlone, Enrico Felice; Gastaldi, Giorgio

2015-10-01

Quantitative intraoperative evaluation of bone quality at implant placement site and postinsertion implant primary stability assessment are two key parameters to perform implant-supported rehabilitation properly. A novel micromotor has been recently introduced allowing to measure bone density at implant placement site and to record implant insertion-related parameters, such as the instantaneous, average and peak insertion torque values, and the insertion torque/depth integral. The aim of this study was to investigate in vivo if any correlation existed between initial bone-to-implant contact (BIC) and bone density and integral values recorded with the instrument. Twenty-five patients seeking for implant-supported rehabilitation of edentulous areas were consecutively treated. Before implant placement, bone density at the insertion site was measured. For each patient, an undersized 3.3 × 8-mm implant was placed, recording the insertion torque/depth integral values. After 15 minutes, the undersized implant was retrieved with a 0.5 mm-thick layer of bone surrounding it. Standard implants were consequently placed. Retrieved implants were analyzed for initial BIC quantification after fixation, dehydration, acrylic resin embedment, sections cutting and grinding, and toluidine-blue and acid fuchsine staining. Correlation between initial BIC values, bone density at the insertion site, and the torque/depth integral values was investigated by linear regression analysis. A significant linear correlation was found to exist between initial BIC and (a) bone density at the insertion site (R = 0.96, explained variance R(2)  = 0.92) and (b) torque/depth integral at placement (R = 0.81, explained variance R(2)  = 0.66). The system provided quantitative, reliable data correlating significantly with immediate postinsertion initial BIC, and could therefore represent a valuable tool both for clinical research and for the oral implantologist in his/her daily clinical

Effects of daily activity recorded by pedometer on peak oxygen consumption (VO2peak), ventilatory threshold and leg extension power in 30- to 69-year-old Japanese without exercise habit.

Science.gov (United States)

Zhang, Jian-Guo; Ohta, Toshiki; Ishikawa-Takata, Kazuko; Tabata, Izumi; Miyashita, Mitsumasa

2003-09-01

The relationships among walk steps, exercise habits and peak oxygen consumption (VO2peak), ventilatory threshold (VT) and leg extension power (LEP) were examined in 709 apparently healthy Japanese subjects (male 372, female 337) aged 30-69 years. Walk steps were evaluated using a pedometer. VO2peak and VT were assessed by a cycle ergometer test, while LEP was measured with an isokinetic leg extension system (Combi, Anaero Press 3500, Japan). Subjects who participated in exercise three times or more a week demonstrated significantly greater VO2peak and VT when compared with subjects without exercise habits. When a separate analysis was conducted on subjects who exercised fewer than three times per week, we found that the subgroup with the highest number of walk steps showed significantly greater VT in all male subjects and female subjects aged 30-49 years, but a significantly greater VO2peak only in females aged 30-49 years, when compared to the subgroup with the fewest walk steps. These results suggest that although some people exercise less than three times a week, if they are quite active in daily life, such activities might also confer benefits upon their fitness.

The reliability of data produced by isokinetic dynamometry (IKD) of ...

African Journals Online (AJOL)

To investigate the feasibility of using isolated knee performance to measure the f-v profile of human muscle in vivo, we were using isokinetic dynamometry (IKD) technique that span the entire f-v profile of skeletal muscle. With institutional ethics approval, eleven healthy males (mean ± SD: age, 24.9 ± 3.1 years; body mass, ...

Preseason physiological profile of soccer and basketball players in different divisions.

Science.gov (United States)

Metaxas, Thomas I; Koutlianos, Nikos; Sendelides, Thomas; Mandroukas, Athanasios

2009-09-01

The purpose of this study was to examine and compare the cardiorespiratory performance and isokinetic muscle strength between Greek soccer and basketball players of different divisions before starting the training season. Study participants included 100 soccer players and 61 basketball players, who were assigned according to the kind of sport and division. All participants underwent anthropometric measurements and performed an exercise test on a treadmill to determine maximal oxygen uptake (VO2max). Peak torque for quadriceps and hamstring muscles was measured on isokinetic dynamometer at angular velocity of 60 degrees/s(-1), 180 degrees/s(-1), and 300 degrees/s(-1). The statistical p value was set at p duration of the maintenance period and to the effect of the training session on each sport, respectively. Finally, a higher level of muscle strength would be preferable in soccer and basketball and would reduce the risk for injuries in the maintenance and rebuilding training periods.

Momentum confinement at low torque

Energy Technology Data Exchange (ETDEWEB)

Solomon, W M [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Burrell, K H [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); De Grassie, J S [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Budny, R [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Groebner, R J [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Kinsey, J E [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Kramer, G J [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Luce, T C [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Makowski, M A [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Mikkelsen, D [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Nazikian, R [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Petty, C C [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Politzer, P A [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Scott, S D [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Zeeland, M A Van [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Zarnstorff, M C [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States)

2007-12-15

Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized beta {beta}{sub N}, by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q{sub min} show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. GLF23 modeling suggests that the role of E x B shearing is quite different between the two plasmas, which may help to explain the different dependence of the momentum confinement on torque.

Low mass planet migration in magnetically torqued dead zones - I. Static migration torque

Science.gov (United States)

McNally, Colin P.; Nelson, Richard P.; Paardekooper, Sijme-Jan; Gressel, Oliver; Lyra, Wladimir

2017-12-01

Motivated by models suggesting that the inner planet forming regions of protoplanetary discs are predominantly lacking in viscosity-inducing turbulence, and are possibly threaded by Hall-effect generated large-scale horizontal magnetic fields, we examine the dynamics of the corotation region of a low-mass planet in such an environment. The corotation torque in an inviscid, isothermal, dead zone ought to saturate, with the libration region becoming both symmetrical and of a uniform vortensity, leading to fast inward migration driven by the Lindblad torques alone. However, in such a low viscosity situation, the material on librating streamlines essentially preserves its vortensity. If there is relative radial motion between the disc gas and the planet, the librating streamlines will no longer be symmetrical. Hence, if the gas is torqued by a large-scale magnetic field so that it undergoes a net inflow or outflow past the planet, driving evolution of the vortensity and inducing asymmetry of the corotation region, the corotation torque can grow, leading to a positive torque. In this paper, we treat this effect by applying a symmetry argument to the previously studied case of a migrating planet in an inviscid disc. Our results show that the corotation torque due to a laminar Hall-induced magnetic field in a dead zone behaves quite differently from that studied previously for a viscous disc. Furthermore, the magnetic field induced corotation torque and the dynamical corotation torque in a low viscosity disc can be regarded as one unified effect.

A method to accurately estimate the muscular torques of human wearing exoskeletons by torque sensors.

Science.gov (United States)

Hwang, Beomsoo; Jeon, Doyoung

2015-04-09

In exoskeletal robots, the quantification of the user's muscular effort is important to recognize the user's motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users' muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user's limb accurately from the measured torque. The user's limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user's muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions.

A Method to Accurately Estimate the Muscular Torques of Human Wearing Exoskeletons by Torque Sensors

Directory of Open Access Journals (Sweden)

Beomsoo Hwang

2015-04-01

Full Text Available In exoskeletal robots, the quantification of the user’s muscular effort is important to recognize the user’s motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users’ muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user’s limb accurately from the measured torque. The user’s limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user’s muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions.

Design of a new torque standard machine based on a torque generation method using electromagnetic force

International Nuclear Information System (INIS)

Nishino, Atsuhiro; Ueda, Kazunaga; Fujii, Kenichi

2017-01-01

To allow the application of torque standards in various industries, we have been developing torque standard machines based on a lever deadweight system, i.e. a torque generation method using gravity. However, this method is not suitable for expanding the low end of the torque range, because of the limitations to the sizes of the weights and moment arms. In this study, the working principle of the torque generation method using an electromagnetic force was investigated by referring to watt balance experiments used for the redefinition of the kilogram. Applying this principle to a rotating coordinate system, an electromagnetic force type torque standard machine was designed and prototyped. It was experimentally demonstrated that SI-traceable torque could be generated by converting electrical power to mechanical power. Thus, for the first time, SI-traceable torque was successfully realized using a method other than that based on the force of gravity. (paper)

Momentum Confinement at Low Torque

International Nuclear Information System (INIS)

Solomon, W.M.; Burrell, K.H.; deGrassie, J.S.; Budny, R.; Groebner, R.J.; Heidbrink, W.W.; Kinsey, J.E.; Kramer, G.J.; Makowski, M.A.; Mikkelsen, D.; Nazikian, R.; Petty, C.C.; Politzer, P.A.; Scott, S.D.; Van Zeeland, M.A.; Zarnstorff, M.C.

2007-01-01

Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized β N , by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co-neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q min show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. The relative importance of E x B shearing between the two is modeled using GLF23 and may suggest a possible explanation.

Electromagnetic torque on the toroidal plasma and the error-field induced torque

International Nuclear Information System (INIS)

Pustovitov, V. D.

2007-01-01

The electromagnetic torque on the toroidal plasma is calculated assuming a linear plasma response to the applied perturbation, which may be the error field or the field created by the correction coils, or both. The result is compared with recently published expressions for the error field induced torque (Zheng et al 2006 Nucl. Fusion 46 L9, Zheng and Kotschenreuther 2006 Phys. Rev. Lett. 97 165001), and the conclusions of these papers are revised. We resolve the problem of the torque resonance raised there. It is shown that the strong increase in the torque due to the static error field must occur at the resistive wall mode stability limit and not at the no-wall stability limit

Effects of isokinetic calf muscle exercise program on muscle strength and venous function in patients with chronic venous insufficiency.

Science.gov (United States)

Ercan, Sabriye; Çetin, Cem; Yavuz, Turhan; Demir, Hilmi M; Atalay, Yurdagül B

2018-05-01

Objective The aim of this study was to observe the change of the ankle joint range of motion, the muscle strength values measured with an isokinetic dynamometer, pain scores, quality of life scale, and venous return time in chronic venous insufficiency diagnosed patients by prospective follow-up after 12-week exercise program including isokinetic exercises. Methods The patient group of this study comprised 27 patients (23 female, 4 male) who were diagnosed with chronic venous insufficiency. An exercise program including isokinetic exercise for the calf muscle was given to patients three days per week for 12 weeks. At the end of 12 weeks, five of the patients left the study due to inadequate compliance with the exercise program. As a result, control data of 22 patients were included. Ankle joint range of active motion, isokinetic muscle strength, pain, quality of life, and photoplethysmography measurements were assessed before starting and after the exercise program. Results Evaluating changes of the starting and control data depending on time showed that all isokinetic muscle strength measurement parameters, range of motion, and overall quality of life values of patients improved. Venous return time values have also increased significantly ( p < 0.05). Conclusion In conclusion, increase in muscle strength has been provided with exercise therapy in patients with chronic venous insufficiency. It has been determined that the increase in muscle strength affected the venous pump and this ensured improvement in venous function and range of motion of the ankle. In addition, it has been detected that pain reduced and quality of life improved after the exercise program.

Influence of Joint Angle on EMG-Torque Model During Constant-Posture, Torque-Varying Contractions.

Science.gov (United States)

Liu, Pu; Liu, Lukai; Clancy, Edward A

2015-11-01

Relating the electromyogram (EMG) to joint torque is useful in various application areas, including prosthesis control, ergonomics and clinical biomechanics. Limited study has related EMG to torque across varied joint angles, particularly when subjects performed force-varying contractions or when optimized modeling methods were utilized. We related the biceps-triceps surface EMG of 22 subjects to elbow torque at six joint angles (spanning 60° to 135°) during constant-posture, torque-varying contractions. Three nonlinear EMG σ -torque models, advanced EMG amplitude (EMG σ ) estimation processors (i.e., whitened, multiple-channel) and the duration of data used to train models were investigated. When EMG-torque models were formed separately for each of the six distinct joint angles, a minimum "gold standard" error of 4.01±1.2% MVC(F90) resulted (i.e., error relative to maximum voluntary contraction at 90° flexion). This model structure, however, did not directly facilitate interpolation across angles. The best model which did so achieved a statistically equivalent error of 4.06±1.2% MVC(F90). Results demonstrated that advanced EMG σ processors lead to improved joint torque estimation as do longer model training durations.

Posterior Tibial Slope Angle Correlates With Peak Sagittal and Frontal Plane Knee Joint Loading During Robotic Simulations of Athletic Tasks

Science.gov (United States)

Bates, Nathaniel A.; Nesbitt, Rebecca J.; Shearn, Jason T.; Myer, Gregory D.; Hewett, Timothy E.

2017-01-01

Background Tibial slope angle is a nonmodifiable risk factor for anterior cruciate ligament (ACL) injury. However, the mechanical role of varying tibial slopes during athletic tasks has yet to be clinically quantified. Purpose To examine the influence of posterior tibial slope on knee joint loading during controlled, in vitro simulation of the knee joint articulations during athletic tasks. Study Design Descriptive laboratory study. Methods A 6 degree of freedom robotic manipulator positionally maneuvered cadaveric knee joints from 12 unique specimens with varying tibial slopes (range, −7.7° to 7.7°) through drop vertical jump and sidestep cutting tasks that were derived from 3-dimensional in vivo motion recordings. Internal knee joint torques and forces were recorded throughout simulation and were linearly correlated with tibial slope. Results The mean (6SD) posterior tibial slope angle was 2.2° ± 4.3° in the lateral compartment and 2.3° ± 3.3° in the medial compartment. For simulated drop vertical jumps, lateral compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee adduction (r = 0.60–0.65), flexion (r = 0.64–0.66), lateral (r = 0.57–0.69), and external rotation torques (r = 0.47–0.72) as well as inverse correlations with peak abduction (r = −0.42 to −0.61) and internal rotation torques (r = −0.39 to −0.79). Only frontal plane torques were correlated during sidestep cutting simulations. For simulated drop vertical jumps, medial compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee flexion torque (r = 0.64–0.69) and lateral knee force (r = 0.55–0.74) as well as inverse correlations with peak external torque (r = −0.34 to 20.67) and medial knee force (r = −0.58 to −0.59). These moderate correlations were also present during simulated sidestep cutting. Conclusion The investigation supported the theory that increased posterior

Electron spin torque in atoms

International Nuclear Information System (INIS)

Hara, Takaaki; Senami, Masato; Tachibana, Akitomo

2012-01-01

The spin torque and zeta force, which govern spin dynamics, are studied by using monoatoms in their steady states. We find nonzero local spin torque in transition metal atoms, which is in balance with the counter torque, the zeta force. We show that d-orbital electrons have a crucial effect on these torques. Nonzero local chirality density in transition metal atoms is also found, though the electron mass has the effect to wash out nonzero chirality density. Distribution patterns of the chirality density are the same for Sc–Ni atoms, though the electron density distributions are different. -- Highlights: ► Nonzero local spin torque is found in the steady states of transition metal atoms. ► The spin steady state is realized by the existence of a counter torque, zeta force. ► D-orbital electrons have a crucial effect on the spin torque and zeta force. ► Nonzero local chiral density is found in spite of the washout by the electron mass. ► Chiral density distribution have the same pattern for Sc–Ni atoms.

Adaptive Engine Torque Compensation with Driveline Model

Directory of Open Access Journals (Sweden)

Park Jinrak

2018-01-01

Full Text Available Engine net torque is the total torque generated by the engine side, and includes the fuel combustion torque, the friction torque, and additionally the starter motor torque in case of hybrid vehicles. The engine net torque is utilized to control powertrain items such as the engine itself, the transmission clutch, also the engine clutch, and it must be accurate for the precise powertrain control. However, this net torque can vary with the engine operating conditions like the engine wear, the changes of the atmospheric pressure and the friction torque. Thus, this paper proposes the adaptive engine net torque compensator using driveline model which can cope with the net torque change according to engine operating conditions. The adaptive compensator was applied on the parallel hybrid vehicle and investigated via MATLAB Simcape Driveline simulation.

Child–adult differences in the kinetics of torque development

Science.gov (United States)

DOTAN, RAFFY; MITCHELL, CAMERON; COHEN, ROTEM; GABRIEL, DAVID; KLENTROU, PANAGIOTA; FALK, BAREKET

2013-01-01

Children have lower size-normalised maximal voluntary force, speed, and power than adults. It has been hypothesised that these and other age-related performance differences are due to lesser type-II motor-unit utilisation in children. This should be manifested as slower force kinetics in explosive muscle contractions. The purpose of this study was to investigate the nature of child–adult force-kinetics differences and whether the latter could support that hypothesis. Untrained boys (n = 20) and men (n = 20) (10.1 ± 1.3 and 22.9 ± 4.4 years, respectively), performed maximal, explosive, isometric elbow flexions and knee extensions on a Biodex dynamometer. Peak torque (MVC), times to 10–100% MVC, and other kinetics parameters were determined. The boys’ body-mass-normalised knee extension MVC, peak rate of torque development, and %MVC at 100 ms were 26, 17 and 23% lower compared with the men and their times to 30% and 80% MVC were 24 and 48% longer, respectively. Elbow flexion kinetics showed similar or greater differences. The findings illuminate boys’ inherent disadvantage in tasks requiring speed or explosive force. It is demonstrated that the extent of the boys–men kinetics disparity cannot be explained by muscle-composition and/or musculo-tendinous-stiffness differences. We suggest therefore that the findings indirectly support children’s lower utilisation of type-II motor units. PMID:23320937

40 CFR 1065.310 - Torque calibration.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Torque calibration. 1065.310 Section... Conditions § 1065.310 Torque calibration. (a) Scope and frequency. Calibrate all torque-measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after major...

Installation Torque Tables for Noncritical Applications

Science.gov (United States)

Rivera-Rosario, Hazel T.; Powell, Joseph S.

2017-01-01

The objective of this project is to define torque values for bolts and screws when loading is not a concern. Fasteners require a certain torque to fulfill its function and prevent failure. NASA Glenn Research Center did not have a set of fastener torque tables for non-critical applications without loads, usually referring to hand-tight or wrench-tight torqueing. The project is based on two formulas, torque and pullout load. Torque values are calculated giving way to preliminary data tables. Testing is done to various bolts and metal plates, torqueing them until the point of failure. Around 640 torque tables were developed for UNC, UNF, and M fasteners. Different lengths of thread engagement were analyzed for the 5 most common materials used at GRC. The tables were put together in an Excel spreadsheet and then formatted into a Word document. The plan is to later convert this to an official technical publication or memorandum.

Nonparetic Knee Extensor Strength Is the Determinant of Exercise Capacity of Community-Dwelling Stroke Survivors

Directory of Open Access Journals (Sweden)

Wei-Te Wang

2014-01-01

Full Text Available Objective. To investigate the relationship among walking speed, exercise capacity, and leg strength in community dwelling stroke subjects and to evaluate which one was the leading determinant factor of them. Design. This is a descriptive, cross-sectional study. Thirty-five chronic stroke patients who were able to walk independently in their community were enrolled. Walking speed was evaluated by using the 12-meter walking test. A maximal exercise test was used to determine the stroke subjects’ exercise capacity. Knee extensor strength, measured as isokinetic torque, was assessed by isokinetic dynamometer. Results. The main walking speed of our subjects was 0.52 m/s. Peak oxygen uptake (VO2 peak was 1.21±0.43 L/min. Knee extensor strength, no matter whether paretic or nonparetic side, was significantly correlated to 12-meter walking speed and exercise capacity. Linear regression also showed the strength of the affected knee extensor was the determinant of walking speed and that of the nonparetic knee extensor was the determinant of exercise capacity in community dwelling stroke subjects. Conclusions. Walking speed and peak oxygen uptake were markedly decreased after stroke. Knee extensor strength of nonparetic leg was the most important determinant of exercise capacity of the community-dwelling stroke subjects. Knee extensor strengthening should be emphasized to help stroke patient to achieve optimal community living.

Nonparetic knee extensor strength is the determinant of exercise capacity of community-dwelling stroke survivors.

Science.gov (United States)

Wang, Wei-Te; Huang, Ling-Tzu; Chou, Ya-Hui; Wei, Ta-Sen; Lin, Chung-Che

2014-01-01

To investigate the relationship among walking speed, exercise capacity, and leg strength in community dwelling stroke subjects and to evaluate which one was the leading determinant factor of them. This is a descriptive, cross-sectional study. Thirty-five chronic stroke patients who were able to walk independently in their community were enrolled. Walking speed was evaluated by using the 12-meter walking test. A maximal exercise test was used to determine the stroke subjects' exercise capacity. Knee extensor strength, measured as isokinetic torque, was assessed by isokinetic dynamometer. The main walking speed of our subjects was 0.52 m/s. Peak oxygen uptake (VO₂ peak) was 1.21 ± 0.43 L/min. Knee extensor strength, no matter whether paretic or nonparetic side, was significantly correlated to 12-meter walking speed and exercise capacity. Linear regression also showed the strength of the affected knee extensor was the determinant of walking speed and that of the nonparetic knee extensor was the determinant of exercise capacity in community dwelling stroke subjects. Walking speed and peak oxygen uptake were markedly decreased after stroke. Knee extensor strength of nonparetic leg was the most important determinant of exercise capacity of the community-dwelling stroke subjects. Knee extensor strengthening should be emphasized to help stroke patient to achieve optimal community living.

Removal torque of nail interlocking screws is related to screw proximity to the fracture and screw breakage.

Science.gov (United States)

White, Alexander A; Kubacki, Meghan R; Samona, Jason; Telehowski, Paul; Atkinson, Patrick J

2016-06-01

Studies have shown that titanium implants can be challenging to explant due to the material's excellent biocompatibility and resulting osseointegration. Clinically, titanium alloy nail interlocking screws may require removal to dynamize a construct or revise the nail due to nonunion, infection, pain, or periprosthetic fracture. This study was designed to determine what variables influence the removal torque for titanium alloy interlocking screws. An intramedullary nail with four interlocking screws was used to stabilize a 1-cm segmental femoral defect in a canine model for 16 weeks. The animals were observed to be active following a several-day recovery after surgery. In six animals, the femora and implanted nail/screws were first tested to failure in torsion to simulate periprosthetic fracture of an implant after which the screws were then removed. In four additional animals, the screws were removed without mechanical testing. Both intraoperative insertional and extraction torques were recorded for all screws. Mechanical testing to failure broke 10/24 screws. On average, the intact screws required 70% of the insertional torque during removal while broken screws only required 16% of the insertional torque (p torque than the outboard distal screw (p torque was ∼80°. The peak axial load did not significantly correlate with the torque required to remove the screws. On average, the removal torque was lower than at the time of insertion, and less torque was required to remove broken screws and screws remote to the fracture. However, broken screws will require additional time to retrieve the remaining screw fragment. This study suggests that broken screws and screws in prematurely active patients will require less torque to remove. © IMechE 2016.

Neuromuscular Changes in Female Collegiate Athletes Resulting From a Plyometric Jump-Training Program.

Science.gov (United States)

Wilkerson, Gary B.; Colston, Marisa A.; Short, Nancy I.; Neal, Kristina L.; Hoewischer, Paul E.; Pixley, Jennifer J.

2004-03-01

OBJECTIVE: To assess performance changes induced by a 6- week plyometric jump-training program. DESIGN AND SETTING: We used a quasiexperimental design to compare groups formed on the basis of team membership. Testing was conducted in an athletic training research laboratory, both before and after a 6-week period of preseason basketball conditioning. SUBJECTS: Nineteen female collegiate basketball players from a National Collegiate Athletic Association Division I program (8 subjects) and a National Association of Intercollegiate Athletics Division II program (11 subjects) who had no history of anterior cruciate ligament injury and who had no history of any lower extremity injury during the preceding 6 months. MEASUREMENTS: The variables of primary interest were hamstrings and quadriceps isokinetic peak torque. Of secondary interest were 5 variables derived from step-down and lunging maneuvers performed on a computerized forceplate system and 4 variables derived from tracking the position of the body core during performance of a T-pattern agility drill with a computerized infrared tracking system. RESULTS: A significant group x trial interaction was found for hamstrings peak torque at 60 degrees.s(-1) (F(1,17) = 9.16, P =.008.), and the proportion of total variance attributable to the treatment effect produced by the jump-training program was relatively large (eta(2) =.35, omega(2) =.30). None of the other variables demonstrated statistically significant changes. CONCLUSIONS: Our primary results support plyometric jump training as a strategy for improving neuromuscular attributes that are believed to reduce the risk of anterior cruciate ligament injury in female college basketball players. They also provide the basis for reasonable isokinetic strength goals.

14 CFR 27.361 - Engine torque.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for maximum...

The effect of peculiar complex core balance training on isokinetic muscle functions of the knee and lumbus.

Science.gov (United States)

Lee, Myungsun; Han, Gunsoo

2016-04-01

[Purpose] This study aimed to investigate the effect of peculiar complex core balance training on the isokinetic muscle function of the knee joint and lumbus to provide fundamental data for establishing a training program that focuses on improving the performance and prevention of injury by developing the core and low extremity muscles. [Subjects and Methods] The participants in this study included a total of ten high school athletes involved in a throwing event for over five years. The subjects were randomly divided into two groups: The experimental group (N=5) and the control group (N=5). The experimental group underwent peculiar complex core balance training. [Results] According to the analysis of covariance, there was a significant effect of peculiar complex core balance training. Therefore, the isokinetic muscle function of the knee joint and lumbus in the experimental group participating in peculiar complex core balance training was significantly increased compared to the control group. [Conclusion] It is concluded that peculiar complex core balance training had a positive effect on the isokinetic muscle function of the knee and lumbus in throwing event athletes.

[Chronic chondromalacia of the patella: comparison of morphological (magnetic resonance) and functional findings (isokinetic parameters) after rehabilitation].

Science.gov (United States)

Felicetti, G; Avanza, F; Fiori, M; Brignoli, E; Rovescala, R

1996-01-01

The knee is a common site for injuries of the cartilage, capsule and ligament, which calls for the use of noninvasive techniques to assess injury severity properly and to plan adequate rehabilitation. Our study was aimed at comparing MR with isokinetic findings. To this purpose, 40 patients were examined; they were all affected with chondromalacia patellae, grades I-III, previously diagnosed at arthroscopy. Namely, 8 patients had grade I and 32 grades II and III chondromalacia. After MR and isokinetic exams, all patients were submitted to a standardized rehabilitation program. Our results indicate a marked decrease in quadriceps strength, especially in the most severe cases; in less severe cases, recovery was complete at 6 months, while the deficit remained in grades II and III injuries. MR yield was not relevant in 4 of 8 cases, while isokinetic findings were negative in one case. Both methods were positive in the most severe cases. At 6 months, both functional and MR findings were normal in grade I injuries, while some alterations remained in the others.

Charge-induced spin torque in Weyl semimetals

Science.gov (United States)

Kurebayashi, Daichi; Nomura, Kentaro

In this work, we present phenomenological and microscopic derivations of spin torques in magnetically doped Weyl semimetals. As a result, we obtain the analytical expression of the spin torque generated, without a flowing current, when the chemical potential is modulated. We also find that this spin torque is a direct consequence of the chiral anomaly. Therefore, observing this spin torque in magnetic Weyl semimetals might be an experimental evidence of the chiral anomaly. This spin torque has also a great advantage in application. In contrast to conventional current-induced spin torques such as the spin-transfer torques, this spin torque does not accompany a constant current flow. Thus, devices using this operating principle is free from the Joule heating and possibly have higher efficiency than devices using conventional current-induced spin torques. This work was supported by JSPS KAKENHI Grant Number JP15H05854 and JP26400308.

Isokinetic muscle strength and readiness to return to sport following anterior cruciate ligament reconstruction: is there an association? A systematic review and a protocol recommendation.

Science.gov (United States)

Undheim, Marit Baste; Cosgrave, Ciaran; King, Enda; Strike, Siobhán; Marshall, Brendan; Falvey, Éanna; Franklyn-Miller, Andrew

2015-10-01

Following anterior cruciate ligament reconstruction (ACLR), strength is a key variable in regaining full function of the knee. Isokinetic strength is commonly used as part of the return to sport (RTS) criteria. We systematically reviewed the isokinetic strength evaluation protocols that are currently being used following ACLR. A secondary aim was to suggest an isokinetic protocol that could meet RTS criteria. Articles were searched using ScienceDirect, PubMed and Sage Journals Online, combined with cross-checked reference lists of the publications. Protocol data and outcome measurements and RTS criteria were extracted from each article included in the review. 39 studies met the inclusion criteria and reported their isokinetic strength evaluation protocol following ACLR. The variables that were most commonly used were concentric/concentric mode of contraction (31 studies), angular velocity of 60°/s (29 studies), 3-5 repetitions (24 studies), range of motion of 0-90° (6 studies), and using gravity correction (9 studies). 8 studies reported strength limb symmetry index scores as part of their RTS criteria. There was no standardised isokinetic protocol following ACLR; isokinetic strength measures have not been validated as useful predictors of successful RTS. We propose a standard protocol to allow consistency of testing and accurate comparison of future research. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Relationships of Functional Tests Following ACL Reconstruction: Exploratory Factor Analyses of the Lower Extremity Assessment Protocol.

Science.gov (United States)

DiFabio, Melissa; Slater, Lindsay V; Norte, Grant; Goetschius, John; Hart, Joseph M; Hertel, Jay

2018-03-01

After ACL reconstruction (ACLR), deficits are often assessed using a variety of functional tests, which can be time consuming. It is unknown whether these tests provide redundant or unique information. To explore relationships between components of a battery of functional tests, the Lower Extremity Assessment Protocol (LEAP) was created to aid in developing the most informative, concise battery of tests for evaluating ACLR patients. Descriptive, cross-sectional. Laboratory. 76 ACLR patients (6.86±3.07 months postoperative) and 54 healthy participants. Isokinetic knee flexion and extension at 90 and 180 degrees/second, maximal voluntary isometric contraction for knee extension and flexion, single leg balance, 4 hopping tasks (single, triple, crossover, and 6-meter timed hop), and a bilateral drop vertical jump that was scored with the Landing Error Scoring System (LESS). Peak torque, average torque, average power, total work, fatigue indices, center of pressure area and velocity, hop distance and time, and LESS score. A series of factor analyses were conducted to assess grouping of functional tests on the LEAP for each limb in the ACLR and healthy groups and limb symmetry indices (LSI) for both groups. Correlations were run between measures that loaded on retained factors. Isokinetic and isometric strength tests for knee flexion and extension, hopping, balance, and fatigue index were identified as unique factors for all limbs. The LESS score loaded with various factors across the different limbs. The healthy group LSI analysis produced more factors than the ACLR LSI analysis. Individual measures within each factor had moderate to strong correlations. Isokinetic and isometric strength, hopping, balance, and fatigue index provided unique information. Within each category of measures, not all tests may need to be included for a comprehensive functional assessment of ACLR patients due to the high amount of shared variance between them.

THE EFFECT OF CREATINE SUPPLEMENTATION ON ATHLETE ISOKINETIC PERFORMANCE

OpenAIRE

Erkan Faruk ŞİRİN; Suzan YALÇIN

2009-01-01

The purpose of this study is to find the effects of Creatin Monohydrate (CrH2O) on athlete performance (isokinetic power measured as a total workout) used as an ergojenic aid in long-term (6 weeks) supplementation. There are 38 participants willing to join to the study. Their ages are between 20 and 27. All of them are choosed from active athletes. From the findings of this study; all the participants’ in the creatin group have increased the total workout production in all cycles of isokineti...

Spin Orbit Torque in Ferromagnetic Semiconductors

KAUST Repository

Li, Hang

2016-06-21

Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read\\' and `write\\' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall

A Comparison of Isotonic, Isokinetic, and Plyometric Training Methods for Vertical Jump Improvement.

Science.gov (United States)

Miller, Christine D.

This annotated bibliography documents three training methods used to develop vertical jumping ability and power: isotonic, isokinetics, and plyometric training. Research findings on all three forms of training are summarized and compared. A synthesis of conclusions drawn from the annotated writings is presented. The report includes a glossary of…

Use of isokinetic muscle strength as a measure of severity of rheumatoid arthritis

DEFF Research Database (Denmark)

Schiøttz-Christensen, Berit; Lyngberg, K; Keiding, N

2001-01-01

The aim of this study was to study the association between isokinetic muscle strength (IMS) and other clinical indicators of disability and disease activity in patients with rheumatoid arthritis (RA). A cohort of 36 RA patients was followed over a 1-year period with five measurements of disease...

Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

Science.gov (United States)

Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

1994-01-01

To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no-exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min periods.d-1, 5 d.week-1. Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p < 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9* +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.5%, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

Knee-Joint Proprioception During 30-Day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

Science.gov (United States)

Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

1994-01-01

To determine if daily isotonic exercise or isokinetic exercise training coupled with daily log proprioceptive training, would influence log proprioceptive tracking responses during Bed Rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a NO-Exercise (NOE) training control group (n = 5), and IsoTanic Exercise (ITE, n = 7) and IsoKinetic Exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min period / d, 5 d /week. Only the IKE group performed proprioceptive training using a now isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pro-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p less than 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9 +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.50, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both lsotonic exercise training (without additional propriaceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

Influence of the Dzyaloshinskii-Moriya interaction on the spin-torque diode effect

Energy Technology Data Exchange (ETDEWEB)

Tomasello, R., E-mail: tomasello@deis.unical.it [Department of Computer Science, Modelling, Electronics, and System Science, University of Calabria, Rende, CS (Italy); Carpentieri, M. [Department of Electrical and Information Engineering, Politecnico of Bari, via E. Orabona 4, I-70125 Bari (Italy); Finocchio, G. [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, I-98166 Messina (Italy)

2014-05-07

This paper predicts the effect of the Dzyaloshinskii-Moriya interaction (DMI) and spin Hall effect in the spin-torque diode response of a Magnetic Tunnel Junction built over a Tantalum strip. Our results indicate that, for a microwave current large enough, the DMI can change qualitatively the resonant response by splitting the ferromagnetic resonance peak. We also find out that the two modes have a non-uniform spatial distribution.

Influence of the Dzyaloshinskii-Moriya interaction on the spin-torque diode effect

International Nuclear Information System (INIS)

Tomasello, R.; Carpentieri, M.; Finocchio, G.

2014-01-01

This paper predicts the effect of the Dzyaloshinskii-Moriya interaction (DMI) and spin Hall effect in the spin-torque diode response of a Magnetic Tunnel Junction built over a Tantalum strip. Our results indicate that, for a microwave current large enough, the DMI can change qualitatively the resonant response by splitting the ferromagnetic resonance peak. We also find out that the two modes have a non-uniform spatial distribution

Improving the Q:H strength ratio in women using plyometric exercises.

Science.gov (United States)

Tsang, Kavin K W; DiPasquale, Angela A

2011-10-01

Plyometric training programs have been implemented in anterior cruciate ligament injury prevention programs. Plyometric exercises are designed to aid in the improvement of muscle strength and neuromuscular control. Our purpose was to examine the effects of plyometric training on lower leg strength in women. Thirty (age = 20.3 ± 1.9 years) recreationally active women were divided into control and experimental groups. The experimental group performed a plyometric training program for 6 weeks, 3 d·wk(-1). All subjects attended 4 testing sessions: before the start of the training program and after weeks 2, 4, and 6. Concentric quadriceps and hamstring strength (dominant leg) was assessed using an isokinetic dynamometer at speeds of 60 and 120°·s(-1). Peak torque, average peak torque, and average power (AvgPower) were measured. The results revealed a significant (p plyometric group than in the control group at testing session 4 and that AvgPower was greater in the plyometric group than in the control group in testing sessions 2-4. Our results indicate that the plyometric training program increased hamstring strength while maintaining quadriceps strength, thereby improving the Q:H strength ratio.

Measurement of fatigue in knee flexor and extensor muscles.

Science.gov (United States)

Kawabata, Y; Senda, M; Oka, T; Yagata, Y; Takahara, Y; Nagashima, H; Inoue, H

2000-04-01

In order to examine fatigue of the knee flexor and extensor muscles and to investigate the characteristics of muscular fatigue in different sports, a Cybex machine was used to measure muscle fatigue and recovery during isokinetic knee flexion and extension. Eighteen baseball players, 12 soccer players and 13 marathon runners were studied. Each subject was tested in the sitting position and made to perform 50 consecutive right knee bends and stretches at maximum strength. This was done 3 times with an interval of 10 min between each series. The peak torque to body weight ratio and the fatigue rate were determined in each case. In all subjects, the peak torque to body weight ratio was higher for extensors than flexors. Over the 3 trials, the fatigue rate of extensors showed little change, while that of flexors had a tendency to increase. In each subject, knee extensors showed a high fatigue rate but a quick recovery, while knee flexors showed a low fatigue rate but a slow recovery. As the marathon runners had the smallest fatigue rates for both flexors and extensors, we concluded that marathon runners had more stamina than baseball players and soccer players.

Home-based Exercise on Functional Outcome of the Donor Lower Extremity in Oral Cancer Patients after Fibula Flap Harvest

Directory of Open Access Journals (Sweden)

Ting-Yuan Liu

2013-04-01

Full Text Available Background: After harvesting the fibula flap, pain, sensory disturbance, weakness of donor leg, reduced walking endurance, ankle instability, and lower walking speed had been reported. The aim of this study was to quantitatively assess functional outcome of regular home-based exercise on donor ankle strength, endurance, and walking ability after free fibula flap for mandibular reconstruction. Methods: Fourteen patients were recruited. Objective isokinetic testing and a 6-min walk test (6MWT were used to evaluate ankle strength/endurance and walking ability, respectively. Results: There was a significant increase in the peak torque of ankle dorsiflexion/foot inversion of the healthy leg and ankle dorsiflexion/foot eversion of the donor leg after exercise (p < 0.05. After home-based exercise, there was reduced asymmetry in the peak torques of ankle dorsiflexion and foot eversion and the total work of foot eversion between the donor and healthy legs. In 6MWT, no significant difference was found between the walking distances before and after exercise. Conclusion: Regular home-based exercise could improve the strength of ankle dorsiflexion and foot eversion of the donor leg, and get more symmetric ankle motor function between the donor and healthy legs.

Initial intramuscular perfusion pressure predicts early skeletal muscle function following isolated tibial fractures

Directory of Open Access Journals (Sweden)

Haas Norbert P

2008-04-01

Full Text Available Abstract Background The severity of associated soft tissue trauma in complex injuries of the extremities guides fracture treatment and decisively determines patient's prognosis. Trauma-induced microvascular dysfunction and increased tissue pressure is known to trigger secondary soft tissue damage and seems to adversely affect skeletal muscle function. Methods 20 patients with isolated tibial fractures were included. Blood pressure and compartment pressure (anterior and deep posterior compartment were measured continuously up to 24 hours. Corresponding perfusion pressure was calculated. After 4 and 12 weeks isokinetic muscle peak torque and mean power of the ankle joint in dorsal and plantar flexion were measured using a Biodex dynamometer. Results A significant inverse correlation between the anterior perfusion pressure at 24 hours and deficit in dorsiflexion at 4 weeks was found for both, the peak torque (R = -0.83; p Conclusion The functional relationship between the decrease in intramuscular perfusion pressures and muscle performance in the early rehabilitation period indicate a causative and prognostic role of early posttraumatic microcirculatory derangements and skeletal muscle function. Therapeutic concepts aimed at effective muscle recovery, early rehabilitation, and decreased secondary tissue damage, should consider the maintenance of an adequate intramuscular perfusion pressure.

Measuring the uncertainty of tapping torque

DEFF Research Database (Denmark)

Belluco, Walter; De Chiffre, Leonardo

An uncertainty budget is carried out for torque measurements performed at the Institut for Procesteknik for the evaluation of cutting fluids. Thirty test blanks were machined with one tool and one fluid, torque diagrams were recorded and the repeatability of single torque measurements was estimat...

Real time implementation of viable torque and flux controllers and torque ripple minimization algorithm for induction motor drive

International Nuclear Information System (INIS)

Vasudevan, M.; Arumugam, R.; Paramasivam, S.

2006-01-01

Field oriented control (FOC) and direct torque control (DTC) are becoming the industrial standards for induction motors torque and flux control. This paper aims to give a contribution for a detailed comparison between these two control techniques, emphasizing their advantages and disadvantages. The performance of these two control schemes is evaluated in terms of torque and flux ripple and their transient response to step variations of the torque command. Moreover, a new torque and flux ripple minimization technique is also proposed to improve the performance of the DTC drive. Based on the experimental results, the analysis has been presented

Development of a Portable Torque Wrench Tester

Science.gov (United States)

Wang, Y.; Zhang, Q.; Gou, C.; Su, D.

2018-03-01

A portable torque wrench tester (PTWT) with calibration range from 0.5 Nm to 60 Nm has been developed and evaluated for periodic or on-site calibration of setting type torque wrenches, indicating type torque wrenches and hand torque screwdrivers. The PTWT is easy to carry with weight about 10 kg, simple and efficient operation and energy saving with an automatic loading and calibrating system. The relative expanded uncertainty of torque realized by the PTWT was estimated to be 0.8%, with the coverage factor k=2. A comparison experiment has been done between the PTWT and a reference torque standard at our laboratory. The consistency between these two devices under the claimed uncertainties was verified.

14 CFR 23.361 - Engine torque.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously with...

14 CFR 25.361 - Engine torque.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque...

Torque limit of PM motors for field-weakening region operation

Science.gov (United States)

Royak, Semyon [Beachwood, OH; Harbaugh, Mark M [Richfield, OH

2012-02-14

The invention includes a motor controller and technique for controlling a permanent magnet motor. In accordance with one aspect of the present technique, a permanent magnet motor is controlled by receiving a torque command, determining a physical torque limit based on a stator frequency, determining a theoretical torque limit based on a maximum available voltage and motor inductance ratio, and limiting the torque command to the smaller of the physical torque limit and the theoretical torque limit. Receiving the torque command may include normalizing the torque command to obtain a normalized torque command, determining the physical torque limit may include determining a normalized physical torque limit, determining a theoretical torque limit may include determining a normalized theoretical torque limit, and limiting the torque command may include limiting the normalized torque command to the smaller of the normalized physical torque limit and the normalized theoretical torque limit.

Effects of dance exergaming on depressive symptoms, fear of falling and musculoskeletal function in fallers and non-fallers community-dewlling older women.

Science.gov (United States)

Rodrigues, Elisângela Valevein; Gallo, Luiza Herminia; Guimarães, Ana Tereza Bittencourt; Melo Filho, Jarbas; Luna, Bruna Cavon; Gomes, Anna Raquel Silveira

2018-04-19

The aim of this study was to evaluate the effects of a pop dance exergaming protocol on fall risk factors-depressive symptoms, fear of falling and musculoskeletal function-in community-dwelling, older female fallers and non-fallers. There were 47 community-dwelling older women assigned to the Intervention Group [fallers (n=10, 69.8 ± 4.3 years); non-fallers (n = 12, 68.9 ± 3.3 years)] or the Control Group [fallers (n = 12, 73.6 ± 5.4 years); non-fallers (n = 13, 68.7 ± 4.8 years)]. The Control Group maintained their lifestyle and the Intervention Group performed a videogame dance training three times per week for 12 weeks. The Dance Central game for XBOX 360® and Kinect motion sensor was used. The primary outcomes were geriatric depressive symptoms, fear of falling, and concentric and eccentric isokinetic peak torque of quadriceps and hamstrings. Secondary outcomes included cross-sectional area of quadriceps and hamstrings muscles, functionality (Timed Up and Go test, gait speed, the Five Times Sit-to-Stand test) and a fall circumstances and outcomes inventory. The depressive symptoms decreased in the Intervention Fallers Group. The eccentric hamstrings peak torque at 180°/s increased in the Intervention Non-fallers Group. There were no significant differences between groups for the other variables analyzed. The training attendance was 83% for the Intervention Fallers Group and 88% for the Intervention Non-fallers Group. Dance exergaming can be indicated to decrease depressive symptoms in fallers and increase the peak torque in non-fallers among community-dwelling older women.

14 CFR 29.361 - Engine torque.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1) The...

Normative Quadriceps and Hamstring Muscle Strength Values for Female, Healthy, Elite Handball and Football Players.

Science.gov (United States)

Risberg, May A; Steffen, Kathrin; Nilstad, Agnethe; Myklebust, Grethe; Kristianslund, Eirik; Moltubakk, Marie M; Krosshaug, Tron

2018-05-23

Risberg, MA, Steffen, K, Nilstad, A, Myklebust, G, Kristianslund, E, Moltubakk, MM, and Krosshaug, T. Normative quadriceps and hamstring muscle strength values for female, healthy, elite handball and football players. J Strength Cond Res XX(X): 000-000, 2018-This study presents normative values for isokinetic knee extension and flexion muscle strength tests in 350 elite, female, handball (n = 150) and football (n = 200) players. Isokinetic concentric muscle strength tests at 60°·sec were recorded bilaterally using a dynamometer. Peak torque (in Newton meter [N·m]), body mass normalized peak torque (N·m·kg), and hamstring to quadriceps ratio (H:Q ratio) for dominant and nondominant legs were recorded. The female elite players were 20.9 ± 4.0 years, started playing at the elite level at the age of 18.2 ± 2.7 years, with a mean of 9.7 ± 2.2 hours of weekly in-season training. Handball players demonstrated greater quadriceps muscle strength compared with football players (11.0%) (p handball players only (p = 0.012).The H:Q ratio was significantly lower for handball players (0.58) compared with football players (0.60) (p handball and football players can be used to set rehabilitation goals for muscle strength after injury and enable comparison with uninjured legs. Significantly greater quadriceps muscle strength was found for handball players compared with football players, also when normalized to body mass.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

Experimental verification of air flow rate measurement for representative isokinetic air sampling in ventilation stacks

International Nuclear Information System (INIS)

Okruhlica, P.; Mrtvy, M.; Kopecky, Z.

2009-01-01

Nuclear facilities are obliged to monitor their discharge's influence on environment. Main monitored factions in NPP's ventilation stacks are usually noble gasses, particulates and iodine. These factions are monitored in air sampled from ventilation stack by means of sampling rosette and bypass followed with on-line measuring monitors and balance sampling devices with laboratory evaluations. Correct air flow rate measurement and representative iso-kinetic air sampling system is essential for physical correct and metrological accurate evaluation of discharge influence on environment. Pairs of measuring sensors (Anemometer, pressure gauge, thermometer and humidity meter) are symmetrically placed in horizontal projection of stack on positions based on measured air flow velocity distribution characteristic, Analogically diameter of sampling rosette nozzles and their placement in the middle of 6 - 7 annuluses are calculated for assurance of representative iso-kinetic sampling. (authors)

Experimental verification of air flow rate measurement for representative isokinetic air sampling in ventilation stacks

International Nuclear Information System (INIS)

Okruhlica, P.; Mrtvy, M.; Kopecky, Z.

2008-01-01

Nuclear facilities are obliged to monitor their discharge's influence on environment. Main monitored factions in NPP's ventilation stacks are usually noble gasses, particulates and iodine. These factions are monitored in air sampled from ventilation stack by means of sampling rosette and bypass followed with on-line measuring monitors and balance sampling devices with laboratory evaluations. Correct air flow rate measurement and representative iso-kinetic air sampling system is essential for physical correct and metrological accurate evaluation of discharge influence on environment. Pairs of measuring sensors (Anemometer, pressure gauge, thermometer and humidity meter) are symmetrically placed in horizontal projection of stack on positions based on measured air flow velocity distribution characteristic, Analogically diameter of sampling rosette nozzles and their placement in the middle of 6- 7 annuluses are calculated for assurance of representative iso-kinetic sampling. (authors)

TRAINING-INDUCED CHANGES IN THE TOPOGRAPHY OF MUSCLE TORQUES AND MAXIMAL MUSCLE TORQUES IN BASKETBALL PLAYERS

Directory of Open Access Journals (Sweden)

Krzysztof Buśko

2012-01-01

Full Text Available The aim of the study was to detect changes in the maximal muscle torques in male basketball players during a two-year training cycle. We verified the hypothesis that different workloads applied during the preparation and competition periods would result in changes in the maximal muscle torques of the athletes (increase during the former and decrease or no change during the latter period accompanied by no alteration of the percent muscle topography of all the muscle groups tested. The examinations were conducted on nine senior male basketball players from the Polish national team. Estimations of the muscle torques in static conditions were performed at the end of the preparation (measurements I and III and competition (measurements II and IV periods of a two-year training cycle. Eleven muscle groups were studied including flexors and extensors of the trunk and flexors and extensors of the shoulder, the elbow, the hip, the knee, and the ankle. Muscle torques of the shoulder and the elbow insignificantly decreased except for the muscle torque of the flexors of the shoulder. Muscle torques of the flexors and extensors of the trunk as well as of the flexors and extensors of the hip, the knee, and the ankle increased between measurements I and III and between measurements I and IV with the only exception being the muscle torque of the flexors of the knee (which significantly decreased by 7.4% In the case of the flexors and extensors of the trunk and the flexors and extensors of the hip, the changes appeared to be significant. The sum of the muscle torques of the upper limbs markedly decreased between the preparation (measurement I and competition (measurement IV periods. The sum of the muscle torques of the trunk and the lower limbs and the sum of the muscle torques of the eleven muscle groups significantly increased between measurements I and IV. Percent muscle topography significantly decreased for the flexors and extensors of the shoulder and the

The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures

Science.gov (United States)

Grollier, Julie

2013-03-01

Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.

Angular Acceleration without Torque?

Science.gov (United States)

Kaufman, Richard D.

2012-01-01

Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

EMG-Torque Dynamics Change With Contraction Bandwidth.

Science.gov (United States)

Golkar, Mahsa A; Jalaleddini, Kian; Kearney, Robert E

2018-04-01

An accurate model for ElectroMyoGram (EMG)-torque dynamics has many uses. One of its applications which has gained high attention among researchers is its use, in estimating the muscle contraction level for the efficient control of prosthesis. In this paper, the dynamic relationship between the surface EMG and torque during isometric contractions at the human ankle was studied using system identification techniques. Subjects voluntarily modulated their ankle torque in dorsiflexion direction, by activating their tibialis anterior muscle, while tracking a pseudo-random binary sequence in a torque matching task. The effects of contraction bandwidth, described by torque spectrum, on EMG-torque dynamics were evaluated by varying the visual command switching time. Nonparametric impulse response functions (IRF) were estimated between the processed surface EMG and torque. It was demonstrated that: 1) at low contraction bandwidths, the identified IRFs had unphysiological anticipatory (i.e., non-causal) components, whose amplitude decreased as the contraction bandwidth increased. We hypothesized that this non-causal behavior arose, because the EMG input contained a component due to feedback from the output torque, i.e., it was recorded from within a closed-loop. Vision was not the feedback source since the non-causal behavior persisted when visual feedback was removed. Repeating the identification using a nonparametric closed-loop identification algorithm yielded causal IRFs at all bandwidths, supporting this hypothesis. 2) EMG-torque dynamics became faster and the bandwidth of system increased as contraction modulation rate increased. Thus, accurate prediction of torque from EMG signals must take into account the contraction bandwidth sensitivity of this system.

Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship?

Science.gov (United States)

Lanza, Marcel B; Balshaw, Thomas G; Folland, Jonathan P

2017-08-01

What is the central question of the study? Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship? What is the main finding and its importance? Both agonist (quadriceps) and antagonist coactivation (hamstrings) differed with knee joint angle during maximal isometric knee extensions and thus both are likely to contribute to the angle-torque relationship. Specifically, two independent measurement techniques showed quadriceps activation to be lower at more extended positions. These effects might influence the capacity for neural changes in response to training and rehabilitation at different knee joint angles. The influence of joint angle on knee extensor neuromuscular activation is unclear, owing in part to the diversity of surface electromyography (sEMG) and/or interpolated twitch technique (ITT) methods used. The aim of the study was to compare neuromuscular activation, using rigorous contemporary sEMG and ITT procedures, during isometric maximal voluntary contractions (iMVCs) of the quadriceps femoris at different knee joint angles and examine whether activation contributes to the angle-torque relationship. Sixteen healthy active men completed two familiarization sessions and two experimental sessions of isometric knee extension and knee flexion contractions. The experimental sessions included the following at each of four joint angles (25, 50, 80 and 106 deg): iMVCs (with and without superimposed evoked doublets); submaximal contractions with superimposed doublets; and evoked twitch and doublet contractions whilst voluntarily passive, and knee flexion iMVC at the same knee joint positions. The absolute quadriceps femoris EMG was normalized to the peak-to-peak amplitude of an evoked maximal M-wave, and the doublet-voluntary torque relationship was used to calculate activation with the ITT. Agonist activation, assessed with both normalized EMG and the ITT, was reduced at the more extended compared with the more flexed

Avaliação isocinética em atletas paraolímpicos Isokinetic evaluation in paralympic athletes

Directory of Open Access Journals (Sweden)

Antônio Carlos Silva

2002-06-01

Full Text Available O equilíbrio dos parâmetros de força muscular nas articulações é de grande relevância, tanto no aspecto clínico como para o desempenho atlético. Informações sobre os valores desses parâmetros em atletas olímpicos e principalmente nos paraolímpicos são raras. Neste trabalho apresentamos os resultados da avaliação muscular isocinética (Cybex 6000 realizada na equipe brasileira que participou dos Jogos Paraolímpicos de Sidney 2000. Foram avaliados os músculos flexores e extensores dos joelhos de 11 jogadores de futebol (paralisia cerebral, idade 24,6 ± 4,8 anos; peso 67 ± 5,5kg; altura 177,7 ± 3,8cm e 12 de basquetebol (deficientes mentais, idade 24,7 ± 4,4 anos; peso 76,6 ± 13,4kg; altura 184,4 ± 10cm, e os músculos rotadores internos e rotadores externos de ombros de seis judocas (deficientes visuais, idade 29,8 ± 5,6 anos; peso 87 ± 21,6kg; altura 171,5 ± 6,9cm. Os jogadores de futebol apresentaram relação de equilíbrio muscular entre flexores e extensores de joelhos dentro dos parâmetros de normalidade apesar da fraqueza muscular imposta pela paralisia cerebral. Nos judocas o equilíbrio muscular entre rotadores externos e rotadores internos mostrou-se dentro dos limites de normalidade. A principal característica dos jogadores de basquetebol foi o valor de pico de torque próximo do esperado para indivíduos hígidos não atletas. Os valores numéricos estão apresentados no texto para serem usados como referência para profissionais da área.The balance between agonist and antagonist muscles in the joints is of great relevance to clinical practice and to sports performance. Information about these parameters amongst Olympic and especially Paralympic athletes is scarce. The purpose of this study was to present the results of the isokinetic evaluation (Cybex 6000 of the Brazilian team that participated in the Sydney Paralympic Games. The flexor and extensor muscles of the knee were evaluated in 11 soccer

A non-unity torque sharing function for torque ripple minimization of switched reluctance generators

DEFF Research Database (Denmark)

Park, Kiwoo; Liu, Xiao; Chen, Zhe

2013-01-01

This paper presents a new torque ripple minimization technique for a Switched Reluctance Generator (SRG). Although the SRG has many advantageous characteristics as a generator, it has not been widely employed in the industry. One of the most notorious disadvantages of the SRG is its high torque...

The Fate of the Iliopsoas Muscle in Long-term Follow-up After Open Reduction With a Medial Approach in Developmental Dysplasia of the Hip. Part 2: Isokinetic Muscle Strength Evaluation.

Science.gov (United States)

Yilmaz, Serdar; Aksahin, Ertugrul; Ersoz, Murat; Bicimoglu, Ali

2017-09-01

The impact on long-term weakness of hip flexion of complete iliopsoas tenotomy during open reduction of developmental hip dysplasia with a medial approach has not yet been fully clarified. The purpose of this study was to investigate the isokinetic muscle strength (IMS) of hip flexor and extensor muscles in these patients and also to analyze the effect of spontaneous reattachment of the iliopsoas muscle on IMS measurements. The study included 20 patients. Earlier magnetic resonance imaging examination of all the patients revealed spontaneous reattachment of the iliopsoas in 18 (90%) patients. IMS measurements were performed at 60 and 150 degrees/s. The peak torque, total work (TW), average power (AP), work fatigue, and agonist to antagonist muscle ratio of the operated and nonoperated hips were recorded separately for flexors and extensors. The effect of iliopsoas reattachment on IMS was also evaluated. The mean follow-up period was 16.65±2.16 (13 to 20) years. Total work (P=0.013) and average power (P=0.009) of the flexor muscles and work fatigue of the extensor muscles (P=0.030) of the operated hip were significantly decreased when compared with the nonoperated hips at 150 degrees/s. There was no significant difference between the flexor muscles of the operated and nonoperated hips (Phips. Flexor muscle strength was decreased in the operated hip against low resistance in long-term follow-up after iliopsoas tenotomy. This may reflect that hip muscle strength was decreased after prolonged activities such as sports. However, in forceful activities flexor muscle strength was retained due to iliopsoas reattachment. On the basis of this study we thought that spontaneous reattachment of the iliopsoas tendon substantially preserves muscle strength. Nonetheless possible efforts should be made to surgically reattach the psoas tendon to preserve strength of the muscle. Therapeutic level IV.

Torque scaling in small-gap Taylor-Couette flow with smooth or grooved wall

Science.gov (United States)

Zhu, Bihai; Ji, Zengqi; Lou, Zhengkun; Qian, Pengcheng

2018-03-01

The torque in the Taylor-Couette flow for radius ratios η ≥0.97 , with smooth or grooved wall static outer cylinders, is studied experimentally, with the Reynolds number of the inner cylinder reaching up to Rei=2 ×105 , corresponding to the Taylor number up to Ta =5 ×1010 . The grooves are perpendicular to the mean flow, and similar to the structure of a submersible motor stator. It is found that the dimensionless torque G , at a given Rei and η , is significantly greater for grooved cases than smooth cases. We compare our experimental torques for the smooth cases to the fit proposed by Wendt [F. Wendt, Ing.-Arch. 4, 577 (1993), 10.1007/BF02084936] and the fit proposed by Bilgen and Boulos [E. Bilgen and R. Boulos, J Fluids Eng. 95, 122 (1973), 10.1115/1.3446944], which shows both fits are outside their range for small gaps. Furthermore, an additional dimensionless torque (angular velocity flux) N uω in the smooth cases exhibits an effective scaling of N uω˜T a0.39 in the ultimate regime, which occurs at a lower Taylor number, Ta ≈3.5 ×107 , than the well-explored η =0.714 case (at Ta ≈3 ×108 ). The same effective scaling exponent, 0.39, is also evident in the grooved cases, but for η =0.97 and 0.985, there is a peak before this exponent appears.

Hamstring and Quadriceps Isokinetic Strength Deficits Are Weak Risk Factors for Hamstring Strain Injuries: A 4-Year Cohort Study.

Science.gov (United States)

van Dyk, Nicol; Bahr, Roald; Whiteley, Rodney; Tol, Johannes L; Kumar, Bhavesh D; Hamilton, Bruce; Farooq, Abdulaziz; Witvrouw, Erik

2016-07-01

A hamstring strain injury (HSI) has become the most common noncontact injury in soccer. Isokinetic muscle strength deficits are considered a risk factor for HSIs. However, underpowered studies with small sample sizes unable to determine small associations have led to inconclusive results regarding the role of isokinetic strength and strength testing in HSIs. To examine whether differences in isokinetic strength measures of knee flexion and extension represent risk factors for hamstring injuries in a large cohort of professional soccer players in an adequately powered study design. Cohort study; Level of evidence, 2. A total of 614 professional soccer players from 14 teams underwent isokinetic strength testing during preseason screening. Testing consisted of concentric knee flexion and extension at 60 deg/s and 300 deg/s and eccentric knee extension at 60 deg/s. A clustered multiple logistic regression analysis was used to identify variables associated with the risk of HSIs. Receiver operating characteristic (ROC) curves were calculated to determine sensitivity and specificity. Of the 614 players, 190 suffered an HSI during the 4 seasons. Quadriceps concentric strength at 60 deg/s (odds ratio [OR], 1.41; 95% CI, 1.03-1.92; P = .03) and hamstring eccentric strength at 60 deg/s (OR, 1.37; 95% CI, 1.01-1.85; P = .04) adjusted for bodyweight were independently associated with the risk of injuries. The absolute differences between the injured and uninjured players were 6.9 N·m and 9.1 N·m, with small effect sizes (d hamstring eccentric strength, respectively, indicating a failed combined sensitivity and specificity of the 2 strength variables identified in the logistic regression models. This study identified small absolute strength differences and a wide overlap of the absolute strength measurements at the group level. The small associations between lower hamstring eccentric strength and lower quadriceps concentric strength with HSIs can only be considered as weak

HAMSTRING ARCHITECTURAL AND FUNCTIONAL ADAPTATIONS FOLLOWING LONG VS. SHORT MUSCLE LENGTH ECCENTRIC TRAINING

Directory of Open Access Journals (Sweden)

Kenny Guex

2016-08-01

Full Text Available Most common preventive eccentric-based exercises, such as Nordic hamstring do not include any hip flexion. So, the elongation stress reached is lower than during the late swing phase of sprinting. The aim of this study was to assess the evolution of hamstring architectural (fascicle length and pennation angle and functional (concentric and eccentric optimum angles and concentric and eccentric peak torques parameters following a 3-week eccentric resistance program performed at long (LML versus short muscle length (SML. Both groups performed eight sessions of 3-5x8 slow maximal eccentric knee extensions on an isokinetic dynamometer: the SML group at 0° and the LML group at 80° of hip flexion. Architectural parameters were measured using ultrasound imaging and functional parameters using the isokinetic dynamometer. The fascicle length increased by 4.9% (p<0.01, medium effect size in the SML and by 9.3% (p<0.001, large effect size in the LML group. The pennation angle did not change (p=0.83 in the SML and tended to decrease by 0.7° (p=0.09, small effect size in the LML group. The concentric optimum angle tended to decrease by 8.8° (p=0.09, medium effect size in the SML and by 17.3° (p<0.01, large effect size in the LML group. The eccentric optimum angle did not change (p=0.19, small effect size in the SML and tended to decrease by 10.7° (p=0.06, medium effect size in the LML group. The concentric peak torque did not change in the SML (p=0.37 and the LML (p=0.23 groups, whereas eccentric peak torque increased by 12.9% (p<0.01, small effect size and 17.9% (p<0.001, small effect size in the SML and the LML group, respectively. No group-by-time interaction was found for any parameters. A correlation was found between the training-induced change in fascicle length and the change in concentric optimum angle (r=-0.57, p<0.01. These results suggest that performing eccentric exercises lead to several architectural and functional adaptations. However

Technology on precision measurement of torque and force

International Nuclear Information System (INIS)

2005-12-01

This book gives a descriptions on force standards system about movement of object, direction and structure. Next, it deals with torque standards, torque measuring instrument and torque wrench with how to use, explanations, unit and test. This book written by Korea Association of standards and testing organizations is for exact measurement and test of force and torque.

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.

Computerized Torque Control for Large dc Motors

Science.gov (United States)

Willett, Richard M.; Carroll, Michael J.; Geiger, Ronald V.

1987-01-01

Speed and torque ranges in generator mode extended. System of shunt resistors, electronic switches, and pulse-width modulation controls torque exerted by large, three-phase, electronically commutated dc motor. Particularly useful for motor operating in generator mode because it extends operating range to low torque and high speed.

Effects of the application of ankle functional rehabilitation exercise on the ankle joint functional movement screen and isokinetic muscular function in patients with chronic ankle sprain.

Science.gov (United States)

Ju, Sung-Bum; Park, Gi Duck

2017-02-01

[Purpose] This study was conducted to investigate the effects of ankle functional rehabilitation exercise on ankle joint functional movement screen results and isokinetic muscular function in patients with chronic ankle sprain patients. [Subjects and Methods] In this study, 16 patients with chronic ankle sprain were randomized to an ankle functional rehabilitation exercise group (n=8) and a control group (n=8). The ankle functional rehabilitation exercise centered on a proprioceptive sense exercise program, which was applied 12 times for 2 weeks. To verify changes after the application, ankle joint functional movement screen scores and isokinetic muscular function were measured and analyzed. [Results] The ankle functional rehabilitation exercise group showed significant improvements in all items of the ankle joint functional movement screen and in isokinetic muscular function after the exercise, whereas the control group showed no difference after the application. [Conclusion] The ankle functional rehabilitation exercise program can be effectively applied in patients with chronic ankle sprain for the improvement of ankle joint functional movement screen score and isokinetic muscular function.

Hybrid synchronous motor electromagnetic torque research

Directory of Open Access Journals (Sweden)

Suvorkova Elena E.

2014-01-01

Full Text Available Electromagnetic field distribution models in reluctance and permanent magnet parts were made by means of Elcut. Dependences of electromagnetic torque on torque angle were obtained.

Special-Purpose High-Torque Permanent-Magnet Motors

Science.gov (United States)

Doane, George B., III

1995-01-01

Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

Heat-driven spin torques in antiferromagnets

Science.gov (United States)

Białek, Marcin; Bréchet, Sylvain; Ansermet, Jean-Philippe

2018-04-01

Heat-driven magnetization damping, which is a linear function of a temperature gradient, is predicted in antiferromagnets by considering the sublattice dynamics subjected to a heat-driven spin torque. This points to the possibility of achieving spin torque oscillator behavior. The model is based on the magnetic Seebeck effect acting on sublattices which are exchange coupled. The heat-driven spin torque is estimated and the feasibility of detecting this effect is discussed.

Adaptive force regulation of muscle strengthening rehabilitation device with magnetorheological fluids.

Science.gov (United States)

Dong, Shufang; Lu, Ke-Qian; Sun, Jian Qiao; Rudolph, Katherine

2006-03-01

In rehabilitation from neuromuscular trauma or injury, strengthening exercises are often prescribed by physical therapists to recover as much function as possible. Strengthening equipment used in clinical settings range from low-cost devices, such as sandbag weights or elastic bands to large and expensive isotonic and isokinetic devices. The low-cost devices are incapable of measuring strength gains and apply resistance based on the lowest level of torque that is produced by a muscle group. Resistance that varies with joint angle can be achieved with isokinetic devices in which angular velocity is held constant and variable torque is generated when the patient attempts to move faster than the device but are ineffective if a patient cannot generate torque rapidly. In this paper, we report the development of a versatile rehabilitation device that can be used to strengthen different muscle groups based on the torque generating capability of the muscle that changes with joint angle. The device is low cost, is smaller than other commercially available machines, and can be programmed to apply resistance that is unique to a particular patient and that will optimize strengthening. The core of the device, a damper with smart magnetorheological fluids, provides passive exercise force. A digital adaptive control is capable of regulating exercise force precisely following the muscle strengthening profile prescribed by a physical therapist. The device could be programmed with artificial intelligence to dynamically adjust the target force profile to optimize rehabilitation effects. The device provides both isometric and isokinetic strength training and can be developed into a small, low-cost device that may be capable of providing optimal strengthening in the home.

Tailoring spin-orbit torque in diluted magnetic semiconductors

KAUST Repository

Li, Hang; Wang, Xuhui; Doǧan, Fatih; Manchon, Aurelien

2013-01-01

We study the spin orbit torque arising from an intrinsic linear Dresselhaus spin-orbit coupling in a single layer III-V diluted magnetic semiconductor. We investigate the transport properties and spin torque using the linear response theory, and we report here: (1) a strong correlation exists between the angular dependence of the torque and the anisotropy of the Fermi surface; (2) the spin orbit torque depends nonlinearly on the exchange coupling. Our findings suggest the possibility to tailor the spin orbit torque magnitude and angular dependence by structural design.

Tailoring spin-orbit torque in diluted magnetic semiconductors

KAUST Repository

Li, Hang

2013-05-16

We study the spin orbit torque arising from an intrinsic linear Dresselhaus spin-orbit coupling in a single layer III-V diluted magnetic semiconductor. We investigate the transport properties and spin torque using the linear response theory, and we report here: (1) a strong correlation exists between the angular dependence of the torque and the anisotropy of the Fermi surface; (2) the spin orbit torque depends nonlinearly on the exchange coupling. Our findings suggest the possibility to tailor the spin orbit torque magnitude and angular dependence by structural design.

Influence of Closed Stator Slots on Cogging Torque

DEFF Research Database (Denmark)

Ion, Trifu; Leban, Krisztina Monika; Ritchie, Ewen

2013-01-01

Cogging torque results due interaction of magnetic field of magnets and stator slots, and have negative effects on permanent magnet machines such as vibrations, noise, torque ripples and problems during turbine start-up and cut-in. In order to reduce cogging torque this paper presents a study...... of influence of closed stator slots on cogging torque using magnetic slot wedges....

Biomechanical Assessment of Motor Abilities in Male Handball Players During the Annual Training Macrocycle

Directory of Open Access Journals (Sweden)

Sacewicz Tomasz

2016-12-01

Full Text Available Introduction. The aim of the study was to determine the torque of the knee extensors and flexors of the lead lower limb, the torque of the shoulder extensors and flexors of the dominant upper limb, and the torque generated by the muscles of the kinematic chain going from the trail lower limb to the hand of the dominant limb in male handball players during the annual training macrocycle. Changes in jump height and throwing velocity were also investigated. Material and methods. The study involved 13 handball players from a Polish second-league team. The measurements were performed four times: at the beginning of the preparation period, at the beginning of the season, at the end of the first part of the season, and at the end of the second part of the season. Torque was measured in isokinetic and isometric conditions. Jumping ability was tested using a piezoelectric platform, and throwing velocity was measured with a speed radar gun. Results. The study found statistically significant differences between the relative torque values of the knee extensors (p < 0.002 and flexors (p < 0.003 of the lead leg measured in isokinetic conditions between the first three measurements and the final one. Isokinetic measurement of the torque of the muscles of the kinematic chain going from the trail leg to the hand of the dominant arm decreased in a statistically significant way at the end of the season. As for the results of the measurement of the torque of the shoulder extensors and flexors in static conditions, no statistically significant differences were observed between the four measurements. However, statistically significant differences were noted in jumping ability and throwing velocity in the annual training macrocycle. Conclusions. The results of the study indicate that there is a need to perform regular assessments of players’ strength and jumping ability during the competition period. There is a need to modify the training methods used during the

Electrostatic sensor modeling for torque measurements

Science.gov (United States)

Mika, Michał; Dannert, Mirjam; Mett, Felix; Weber, Harry; Mathis, Wolfgang; Nackenhorst, Udo

2017-09-01

Torque load measurements play an important part in various engineering applications, as for automotive industry, in which the drive torque of a motor has to be determined. A widely used measuring method are strain gauges. A thin flexible foil, which supports a metallic pattern, is glued to the surface of the object the torque is being applied to. In case of a deformation due to the torque load, the change in the electrical resistance is measured. With the combination of constitutive equations the applied torque load is determined by the change of electrical resistance. The creep of the glue and the foil material, together with the temperature and humidity dependence, may become an obstacle for some applications Kapralov and Fesenko (1984). Thus, there have been optical and magnetical, as well as capacitive sensors introduced). This paper discusses the general idea behind an electrostatic capacitive sensor based on a simple draft of an exemplary measurement setup. For better understanding an own electrostatical, geometrical and mechanical model of this setup has been developed.

Electrostatic sensor modeling for torque measurements

Directory of Open Access Journals (Sweden)

M. Mika

2017-09-01

Full Text Available Torque load measurements play an important part in various engineering applications, as for automotive industry, in which the drive torque of a motor has to be determined. A widely used measuring method are strain gauges. A thin flexible foil, which supports a metallic pattern, is glued to the surface of the object the torque is being applied to. In case of a deformation due to the torque load, the change in the electrical resistance is measured. With the combination of constitutive equations the applied torque load is determined by the change of electrical resistance. The creep of the glue and the foil material, together with the temperature and humidity dependence, may become an obstacle for some applications Kapralov and Fesenko(1984. Thus, there have been optical and magnetical, as well as capacitive sensors introduced . This paper discusses the general idea behind an electrostatic capacitive sensor based on a simple draft of an exemplary measurement setup. For better understanding an own electrostatical, geometrical and mechanical model of this setup has been developed.

Exploratory factor analysis for differentiating sensory and mechanical variables related to muscle-tendon unit elongation

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Mauro H. Chagas

2016-01-01

Full Text Available ABSTRACT Background Stretching exercises are able to promote adaptations in the muscle-tendon unit (MTU, which can be tested through physiological and biomechanical variables. Identifying the key variables in MTU adaptations is crucial to improvements in training. Objective To perform an exploratory factor analysis (EFA involving the variables often used to evaluate the response of the MTU to stretching exercises. Method Maximum joint range of motion (ROMMAX, ROM at first sensation of stretching (FSTROM, peak torque (torqueMAX, passive stiffness, normalized stiffness, passive energy, and normalized energy were investigated in 36 participants during passive knee extension on an isokinetic dynamometer. Stiffness and energy values were normalized by the muscle cross-sectional area and their passive mode assured by monitoring the EMG activity. Results EFA revealed two major factors that explained 89.68% of the total variance: 53.13% was explained by the variables torqueMAX, passive stiffness, normalized stiffness, passive energy, and normalized energy, whereas the remaining 36.55% was explained by the variables ROMMAX and FSTROM. Conclusion This result supports the literature wherein two main hypotheses (mechanical and sensory theories have been suggested to describe the adaptations of the MTU to stretching exercises. Contrary to some studies, in the present investigation torqueMAX was significantly correlated with the variables of the mechanical theory rather than those of the sensory theory. Therefore, a new approach was proposed to explain the behavior of the torqueMAX during stretching exercises.

Accuracy of mechanical torque-limiting devices for dental implants.

Science.gov (United States)

L'Homme-Langlois, Emilie; Yilmaz, Burak; Chien, Hua-Hong; McGlumphy, Edwin

2015-10-01

A common complication in implant dentistry is unintentional implant screw loosening. The critical factor in the prevention of screw loosening is the delivery of the appropriate target torque value. Mechanical torque-limiting devices (MTLDs) are the most frequently recommended devices by the implant manufacturers to deliver the target torque value to the screw. Two types of MTLDs are available: friction-style and spring-style. Limited information is available regarding the influence of device type on the accuracy of MTLDs. The purpose of this study was to determine and compare the accuracy of spring-style and friction-style MTLDs. Five MTLDs from 6 different dental implant manufacturers (Astra Tech/Dentsply, Zimmer Dental, Biohorizons, Biomet 3i, Straumann [ITI], and Nobel Biocare) (n=5 per manufacturer) were selected to determine their accuracy in delivering target torque values preset by their manufacturers. All torque-limiting devices were new and there were 3 manufacturers for the friction-style and 3 manufacturers for the spring-style. The procedure of target torque measurement was performed 10 times for each device and a digital torque gauge (Chatillon Model DFS2-R-ND; Ametek) was used to record the measurements. Statistical analysis used nonparametric tests to determine the accuracy of the MTLDs in delivering target torque values and Bonferroni post hoc tests were used to assess pairwise comparisons. Median absolute difference between delivered torque values and target torque values of friction-style and spring-style MTLDs were not significantly different (P>.05). Accuracy of Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly different than Biohorizons torque-limiting devices (Ptorque value. Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly more accurate than Biohorizons (C) torque-limiting devices (Ptorque-limiting devices fell within ±10% of the target torque value preset by the

Integral torque balance in tokamaks

International Nuclear Information System (INIS)

Pustovitov, V.D.

2011-01-01

The study is aimed at clarifying the balance between the sinks and sources in the problem of intrinsic plasma rotation in tokamaks reviewed recently by deGrassie (2009 Plasma Phys. Control. Fusion 51 124047). The integral torque on the toroidal plasma is calculated analytically using the most general magnetohydrodynamic (MHD) plasma model taking account of plasma anisotropy and viscosity. The contributions due to several mechanisms are separated and compared. It is shown that some of them, though, possibly, important in establishing the rotation velocity profile in the plasma, may give small input into the integral torque, but an important contribution can come from the magnetic field breaking the axial symmetry of the configuration. In tokamaks, this can be the error field, the toroidal field ripple or the magnetic perturbation created by the correction coils in the dedicated experiments. The estimates for the error-field-induced electromagnetic torque show that the amplitude of this torque is comparable to the typical values of torques introduced into the plasma by neutral beam injection. The obtained relations allow us to quantify the effect that can be produced by the existing correction coils in tokamaks on the plasma rotation, which can be used in experiments to study the origin and physics of intrinsic rotation in tokamaks. Several problems are proposed for theoretical studies and experimental tests.

TORQUE MEASUREMENT IN WORM AGLOMERATION MACHINE

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Marian DUDZIAK

2014-03-01

Full Text Available The paper presents the operating characteristics of the worm agglomeration machine. The paper indicates the need for continuous monitoring of the value of the torque due to the efficiency of the machine. An original structure of torque meter which is built in the standard drive system of briquetting machine was presented. A number of benefits arising from the application of the proposed solution were presented. Exemplary measurement results obtained by means of this torque meter were presented.

Effect of Active-Assisted Stretching of 30 Seconds and 60 Seconds in Muscle Force

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Mirian dos Santos Monteiro

2018-01-01

Full Text Available This study aims to analyze the interference of the active-assisted stretching technique in muscle strength. Participating in this study were 39 healthy and physically active individuals subdivided into three groups of active-assisted stretching G30 - 30 seconds, G60 - 60 seconds and CG - control. The muscular strength was evaluated using the isokinetic dynamometer, obtaining the analyzed conditions of torque peak, total work and agonist and antagonist relationship of the dorsiflexor and flexor muscles ankle. The values obtained were statistically analyzed by the SPSS from the “t-test for paired sample” (p ≤ 0.05. When analyzing the effect produced by the stretching, it was observed that the 30-second elongation showed a reduction of the average of the muscular torque in all conditions analyzed, with the exception of the relation between the agonist and the left antagonist and the total work of the right plantar flexors, the G60 - 60 seconds group had a reduction in average muscle torque in all conditions analyzed, except for the relation between agonist and left antagonist that obtained an increase in muscle torque and the CG - control group, there was a reduction in the average of the muscular torque in all the analyzed conditions, except for the torque and total work of the left plantar flexor muscles that presented increase. Thus, it can be concluded that there were differences between the groups of active-assisted stretching of 30 and 60 and that the effect produced by stretching did not present a significant reduction of muscle strength.

Improvements in remote equipment torquing and fastening

International Nuclear Information System (INIS)

Garin, J.

1978-01-01

Remote torquing and fastening is a requirement of generic interest for application in an environment not readily accessible to man. The developments over the last 30 years in torque-controlled equipment above 200 nm (150 ft/lb) have not been emphasized. The development of specialized subassemblies to torque and fasten equipment in a remotely controlled environment is an integral part of the Advanced Fuel Recycle Program at Oak Ridge National Laboratory. Commercially available subassemblies have been adapted into a system that would provide remote torquing and fastening in the range of 200 to 750 nm (150 to 550 ft/lb). 9 figures

Temperature dependence of spin-orbit torques in Cu-Au alloys

KAUST Repository

Wen, Yan; Wu, Jun; Li, Peng; Zhang, Qiang; Zhao, Yuelei; Manchon, Aurelien; Xiao, John Q.; Zhang, Xixiang

2017-01-01

We investigated current driven spin-orbit torques in Cu40Au60/Ni80Fe20/Ti layered structures with in-plane magnetization. We have demonstrated a reliable and convenient method to separate dampinglike torque and fieldlike torque by using the second harmonic technique. It is found that the dampinglike torque and fieldlike torque depend on temperature very differently. Dampinglike torque increases with temperature, while fieldlike torque decreases with temperature, which are different from results obtained previously in other material systems. We observed a nearly linear dependence between the spin Hall angle and longitudinal resistivity, suggesting that skew scattering may be the dominant mechanism of spin-orbit torques.

Temperature dependence of spin-orbit torques in Cu-Au alloys

KAUST Repository

Wen, Yan

2017-03-07

We investigated current driven spin-orbit torques in Cu40Au60/Ni80Fe20/Ti layered structures with in-plane magnetization. We have demonstrated a reliable and convenient method to separate dampinglike torque and fieldlike torque by using the second harmonic technique. It is found that the dampinglike torque and fieldlike torque depend on temperature very differently. Dampinglike torque increases with temperature, while fieldlike torque decreases with temperature, which are different from results obtained previously in other material systems. We observed a nearly linear dependence between the spin Hall angle and longitudinal resistivity, suggesting that skew scattering may be the dominant mechanism of spin-orbit torques.

Spin-torque generation in topological insulator based heterostructures

KAUST Repository

Fischer, Mark H.

2016-03-11

Heterostructures utilizing topological insulators exhibit a remarkable spin-torque efficiency. However, the exact origin of the strong torque, in particular whether it stems from the spin-momentum locking of the topological surface states or rather from spin-Hall physics of the topological-insulator bulk, remains unclear. Here, we explore a mechanism of spin-torque generation purely based on the topological surface states. We consider topological-insulator-based bilayers involving ferromagnetic metal (TI/FM) and magnetically doped topological insulators (TI/mdTI), respectively. By ascribing the key theoretical differences between the two setups to location and number of active surface states, we describe both setups within the same framework of spin diffusion of the nonequilibrium spin density of the topological surface states. For the TI/FM bilayer, we find large spin-torque efficiencies of roughly equal magnitude for both in-plane and out-of-plane spin torques. For the TI/mdTI bilayer, we elucidate the dominance of the spin-transfer-like torque. However, we cannot explain the orders of magnitude enhancement reported. Nevertheless, our model gives an intuitive picture of spin-torque generation in topological-insulator-based bilayers and provides theoretical constraints on spin-torque generation due to topological surface states.

Current-induced torques and interfacial spin-orbit coupling

KAUST Repository

Haney, Paul M.; Lee, Hyun-Woo; Lee, Kyung-Jin; Manchon, Aurelien; Stiles, M. D.

2013-01-01

In bilayer systems consisting of an ultrathin ferromagnetic layer adjacent to a metal with strong spin-orbit coupling, an applied in-plane current induces torques on the magnetization. The torques that arise from spin-orbit coupling are of particular interest. Here we use first-principles methods to calculate the current-induced torque in a Pt-Co bilayer to help determine the underlying mechanism. We focus exclusively on the analog to the Rashba torque, and do not consider the spin Hall effect. The details of the torque depend strongly on the layer thicknesses and the interface structure, providing an explanation for the wide variation in results found by different groups. The torque depends on the magnetization direction in a way similar to that found for a simple Rashba model. Artificially turning off the exchange spin splitting and separately the spin-orbit coupling potential in the Pt shows that the primary source of the “fieldlike” torque is a proximate spin-orbit effect on the Co layer induced by the strong spin-orbit coupling in the Pt.

Detecting Casimir torque with an optically levitated nanorod

Science.gov (United States)

Xu, Zhujing; Li, Tongcang

2017-09-01

The linear momentum and angular momentum of virtual photons of quantum vacuum fluctuations can induce the Casimir force and the Casimir torque, respectively. While the Casimir force has been measured extensively, the Casimir torque has not been observed experimentally though it was predicted over 40 years ago. Here we propose to detect the Casimir torque with an optically levitated nanorod near a birefringent plate in vacuum. The axis of the nanorod tends to align with the polarization direction of the linearly polarized optical tweezer. When its axis is not parallel or perpendicular to the optical axis of the birefringent crystal, it will experience a Casimir torque that shifts its orientation slightly. We calculate the Casimir torque and Casimir force acting on a levitated nanorod near a birefringent crystal. We also investigate the effects of thermal noise and photon recoils on the torque and force detection. We prove that a levitated nanorod in vacuum will be capable of detecting the Casimir torque under realistic conditions, and will be an important tool in precision measurements.

Reducing torque ripples in permanent magnet synchronous motor

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Rihab Abdelmoula

2017-09-01

Full Text Available Permanent magnet synchronous motors (PMSMs are exceptionally promising thanks to their many advantages compared with other types of electrical machines. Indeed, PMSMs are characterized by their important torque density, light weight, high air gap flux density, high acceleration, high efficiency and strong power-to-weight ratio. A surface-mounted PMSM (SPMSM is used in this work. The SPMSM is built using a 2D finite element method (FEM. Cogging torque, torque ripples and back-EMF are examined during the design process in order to obtain sinusoidal back-EMF and to minimise torque ripples which are one of the major problems with PMSMs. Two procedures are used to reduce the cogging torque of SPMSM: the effect of slot opening and the influence of skewing the stator laminations. Cogging torque factor tc and the torque ripples factor tr have been calculated to compare the two configurations (open slots and closed slots. Then, the configuration with closed slots is utilised with skewing the stator laminations for different angle 0°, 10° and 15°.

Current-induced torques and interfacial spin-orbit coupling

KAUST Repository

Haney, Paul M.

2013-12-19

In bilayer systems consisting of an ultrathin ferromagnetic layer adjacent to a metal with strong spin-orbit coupling, an applied in-plane current induces torques on the magnetization. The torques that arise from spin-orbit coupling are of particular interest. Here we use first-principles methods to calculate the current-induced torque in a Pt-Co bilayer to help determine the underlying mechanism. We focus exclusively on the analog to the Rashba torque, and do not consider the spin Hall effect. The details of the torque depend strongly on the layer thicknesses and the interface structure, providing an explanation for the wide variation in results found by different groups. The torque depends on the magnetization direction in a way similar to that found for a simple Rashba model. Artificially turning off the exchange spin splitting and separately the spin-orbit coupling potential in the Pt shows that the primary source of the “fieldlike” torque is a proximate spin-orbit effect on the Co layer induced by the strong spin-orbit coupling in the Pt.

Isokinetic strength effects of FIFA'a "The 11+" injury prevention training programme

DEFF Research Database (Denmark)

Brito, João; Figueiredo, Pedro; Fernandes, Luís

2010-01-01

The purpose of this study was to evaluate whether FIFA's Medical Assessment and Research Centre (F-MARC) injury prevention programme, "The 11+", improves isokinetic strength of the knee extensor and flexor muscles in sub-elite soccer players. Twenty players aged 22.3 ± 4.2 yr performed "The 11+" 3...... significantly improved the conventional H/Q ratio at 60°/s by 14.8{\\%} and the DCR by 13.8% in the non-dominant limb (pknee joint....

Isometric torque-angle relationship and movement-related activity of human elbow flexors: implications for the equilibrium-point hypothesis.

Science.gov (United States)

Hasan, Z; Enoka, R M

1985-01-01

Since the moment arms for the elbow-flexor muscles are longest at intermediate positions of the elbow and shorter at the extremes of the range of motion, it was expected that the elbow torque would also show a peak at an intermediate angle provided the activity of the flexor muscles remained constant. We measured the isometric elbow torque at different elbow angles while the subject attempted to keep constant the electromyographic activity (EMG) of the brachioradialis muscle. The torque-angle relationship thus obtained exhibited a peak, as expected, but the shape of the relationship varied widely among subjects. This was due in part to differences in the variation of the biceps brachii EMG with elbow angle among the different subjects. The implications of these observations for the equilibrium-point hypothesis of movement were investigated as follows. The subject performed elbow movements in the presence of an external torque (which tended to extend the elbow joint) provided by a weight-and-pulley arrangement. We found in the case of flexion movements that invariably there was a transient increase in flexor EMG, as would seem necessary for initiating the movement. However, the steady-state EMG after the movement could be greater or less than the pre-movement EMG. Specifically, the least flexor EMG was required for equilibrium in the intermediate range of elbow angles, compared to the extremes of the range of motion. The EMG-angle relationship, however, varied with the muscle and the subject. The observation that the directions of change in the transient and the steady-state EMG are independent of each other militates against the generality of the equilibrium-point hypothesis. However, a form of the hypothesis which includes the effects of the stretch reflex is not contradicted by this observation.

Aplicación de la dinamometría isocinética para establecer perfiles de riesgo de lesión isquiosural en futbolistas profesionales. [The use of isokinetic dynamometry to establish risk profiles of hamstring injury in professional football players].

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Victor Moreno-Perez

2013-10-01

torque of the hamstring musculature was found, are useful variables to establish risk profiles for hamstring injury in professional football players. Twenty players of a Second Division team of the Liga de Fútbol Profesional bilaterally performed an isokinetic test of eccentric knee flexion at 30º/s and concentric knee extension at 240º/s during the pre-season. The Flexexc30/Extcon240 ratio and the knee angle of peak torque were calculated, and the players’ injuries were registered throughout the season. The results showed that two of the five injured players had Flexexc30/Extcon240 ratios lower than 0.89, value that has been previously used to determine the imbalance between knee flexor and extensor strength and the risk of injury (Croisier, Ganteaume, Binet, Genty, and Ferret, 2008. In addition, another two injured players obtained ratios between 0.93 and 1.00. On the other hand, no differences in the knee angle of peak torque between injured and non-injured players were found. These results indicate that the Flexexc30/Extcon240 ratio may be a useful index to determine the risk of hamstring injury in professional football players.http://dx.doi.org/10.5232/ricyde2013.03403

Comparative analysis of quadriceps and hamstrings strength in knee osteoarthritis before and after total knee arthroplasty: a cross-sectional study

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Naasson Trindade Cavanellas

Full Text Available ABSTRACT Objective: Compare the maximal isokinetic muscle strength of knee extensor and flexor muscles between patients with knee osteoarthritis and patients submitted to total knee arthroplasty. Methods: Volunteers were divided into five groups (n = 20: Control; Ahlbäck I and II; Ahlbäck IV; six months after total knee arthroplasty; 12 months after total knee arthroplasty. An isokinetic knee strength evaluation was conducted for the quadriceps and hamstrings at 60°/s. Results: Significant differences in the peak torque of the quadriceps and hamstrings were found among the groups (p < 0.001. The Ahlbäck IV, six-month, and 12-month postoperative groups demonstrated lower values when compared to the Control and Ahlbäck I and II groups. When percentage values were compared to the Control group, mean differences ranged from 7% to 41%. Conclusion: Patients with healthy knees or early stage osteoarthritis have higher quadriceps and hamstrings strengths than those with a more advanced stage of the disease, even after knee replacement. These findings suggest that the traditional rehabilitation programs do not recover strength to levels observed in individuals without knee osteoarthritis.

Combined Effects of Lignosus rhinocerotis Supplementation and Resistance Training on Isokinetic Muscular Strength and Power, Anaerobic and Aerobic Fitness Level, and Immune Parameters in Young Males.

Science.gov (United States)

Chen, Chee Keong; Hamdan, Nor Faeiza; Ooi, Foong Kiew; Wan Abd Hamid, Wan Zuraida

2016-01-01

This study investigated the effects of Lignosus rhinocerotis (LRS) supplementation and resistance training (RT) on isokinetic muscular strength and power, anaerobic and aerobic fitness, and immune parameters in young males. Participants were randomly assigned to four groups: Control (C), LRS, RT, and combined RT-LRS (RT-LRS). Participants in the LRS and RT-LRS groups consumed 500 mg of LRS daily for 8 weeks. RT was conducted 3 times/week for 8 weeks for participants in the RT and RT-LRS groups. The following parameters were measured before and after the intervention period: Anthropometric data, isokinetic muscular strength and power, and anaerobic and aerobic fitness. Blood samples were also collected to determine immune parameters. Isokinetic muscular strength and power were increased ( P anaerobic power and capacity and aerobic fitness in this group. Similarly, RT group had increases ( P anaerobic power and capacity, aerobic fitness, T lymphocytes (CD3 and CD4), and B lymphocytes (CD19) counts were observed in the RT group. RT elicited increased isokinetic muscular strength and power, anaerobic and aerobic fitness, and immune parameters among young males. However, supplementation with LRS during RT did not provide additive benefits.

Estimating Torque Imparted on Spacecraft Using Telemetry

Science.gov (United States)

Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

2013-01-01

There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

Changes in muscle strength in patients with statin myalgia.

Science.gov (United States)

Panza, Gregory A; Taylor, Beth A; Roman, William; Thompson, Paul D

2014-10-15

Statins can produce myalgia or muscle pain, which may affect medication adherence. We measured the effects of statins on muscle strength in patients with previous statin myalgia. Leg isokinetic extension average power at 60° per second (-8.8 ± 10.5N-M, p = 0.02) and average peak torque at 60° per second (-14.0 ± 19.7N-M, p = 0.04) decreased slightly with statin use, but 8 of 10 other variables for leg strength did not change (all p >0.13). Handgrip, muscle pain, respiratory exchange ratio, and daily activity also did not change (all p >0.09). In conclusion, statin myalgia is not associated with reduced muscle strength or muscle performance. Published by Elsevier Inc.

Robust spin transfer torque in antiferromagnetic tunnel junctions

KAUST Repository

Saidaoui, Hamed Ben Mohamed

2017-04-18

We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling electrical manipulation of the Néel antiferromagnetic order parameter is out of plane, ∼n×p, while the torque competing with the antiferromagnetic exchange is in plane, ∼n×(p×n). Here, p and n are the Néel order parameter direction of the reference and free layers, respectively. Their bias dependence shows behavior similar to that in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias, while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than that in antiferromagnetic metallic spin valves due to the tunneling nature of spin transport.

Torque control for electric motors

Science.gov (United States)

Bernard, C. A.

1980-01-01

Method for adjusting electric-motor torque output to accomodate various loads utilizes phase-lock loop to control relay connected to starting circuit. As load is imposed, motor slows down, and phase lock is lost. Phase-lock signal triggers relay to power starting coil and generate additional torque. Once phase lock is recoverd, relay restores starting circuit to its normal operating mode.

Bevel gear driver and method having torque limit selection

Science.gov (United States)

Cook, Joseph S., Jr.

1994-08-01

This invention comprises a torque drive mechanism utilizing axially translatable, mutually engageable transmission members having mating crown gears, driven and driving members with a three-element drive train being biased together by resilient means or by a fluid actuator system, the apparatus being operable to transmit a precisely controlled degree of torque to a driven member. The apparatus is applicable for use in hand tools and as a replacement for impact torque drivers, torque wrenches, motorized screw drivers, or the like, wherein the applied torque must be precisely controlled or limited. The bevel torque drive includes a drive gear which is axially displaceable and rotatable within cylindrical driver housing, a rotatable intermediate gear, and an output gear. Key rotationally secures displaceable gear with respect to input shaft but permits axial movement therebetween. A thrust bearing is preferably connected to the lower end of shaft for support to reduce play and friction between shaft and a transmission joint disc during rotation of the gear train. Coaxially mounted coiled spring is footed against displaceable gear for biasing the displaceable gear toward and into engagement with the intermediate gear for driving intermediate gear and output gear. Torque control is achieved by the use of straight or spiral beveled gears which are of configurations adapted to withdraw from mutual engagement upon the torque exceeding a predetermined limit. The novel, advantageous features of the invention include the configuration of the mating, crown gear sets and the axially translatable, slidable drive gear. The mechanism is capable of transmitting a high degree of torque within a narrow, compact transmission housing. The compact size and narrow, elongated configuration of the housing is particularly applicable for use in hand tools and in multiple torque driver mechanisms in which it is necessary to drive multiple fasteners which are located in close proximity. Prior

Torque Measurement at the Single Molecule Level

Science.gov (United States)

Forth, Scott; Sheinin, Maxim Y.; Inman, James; Wang, Michelle D.

2017-01-01

Methods for exerting and measuring forces on single molecules have revolutionized the study of the physics of biology. However, it is often the case that biological processes involve rotation or torque generation, and these parameters have been more difficult to access experimentally. Recent advances in the single molecule field have led to the development of techniques which add the capability of torque measurement. By combining force, displacement, torque, and rotational data, a more comprehensive description of the mechanics of a biomolecule can be achieved. In this review, we highlight a number of biological processes for which torque plays a key mechanical role. We describe the various techniques that have been developed to directly probe the torque experienced by a single molecule, and detail a variety of measurements made to date using these new technologies. We conclude by discussing a number of open questions and propose systems of study which would be well suited for analysis with torsional measurement techniques. PMID:23541162

Angular dependence of spin-orbit spin-transfer torques

KAUST Repository

Lee, Ki-Seung

2015-04-06

In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

Angular dependence of spin-orbit spin-transfer torques

KAUST Repository

Lee, Ki-Seung; Go, Dongwook; Manchon, Aurelien; Haney, Paul M.; Stiles, M. D.; Lee, Hyun-Woo; Lee, Kyung-Jin

2015-01-01

In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

Avaliação muscular isocinética da articulação do joelho em atletas das seleções brasileiras infanto e juvenil de voleibol masculino Evaluación muscular isocinetica de la articulación de la rodilla en atletas de las selecciones brasileras infanto y juveniles de voleibol masculino Isokinetic muscle evaluation of the knee joint in athletes of the Under-19 and Under-21 Male Brazilian National Volleyball Team

Directory of Open Access Journals (Sweden)

Natalia Franco N. Bittencourt

2005-12-01

. El estudio presente puede servir así, como base para las comparaciones de estudios futuros que evalúen la función muscular isocinética en atletas del voleibol.The vertical jump is a basic volleyball practice that demands a high ability to generate strength and work in the muscles involved, mainly in the quadriceps muscle. Due to such demand, muscle imbalances between extensor and flexor muscles may be present, causing an overloading on the muscle-tendinous structures of the knee joint. Thus, the establishment of normal parameters for the muscle function related to that joint in volleyball athletes is necessary. Therefore, the purpose of this study was to assess through isokinetic dynamometry the peak torque, work peak, agonist/antagonist ratio, and fatigue index of the flexor and extensor of the knee among both volleyball athlete population. The isokinetic flexion and extension tests of the knees were performed in the concentric-concentric seat mode at 60 and 300º/sec. velocity in thirty-six athletes (20 under 19-under 21, and 16 under 21. The data allowed to set the parameters for the muscle function of the knee joint among athletes of the 2003 Under 19-Under 21 and Under 21 Brazilian National Team Selection of Male Volleyball. Athletes presented peak torque and work peak values normalized by the body mass to the upper quadriceps to the mean normal values for the athletes and non-athletes populations. Compared to other categories, the under 21 athletes presented significantly higher values for the agonist/antagonist ratio, and peak work ratio of the knee flexors at 60º/sec. velocity. Furthermore, the agonist/antagonist ratio was lower than the reference value expected for both categories, thus characterizing predominance in the extensor musculature over the flexor musculature. The fatigue index was close to what would be expected for the majority of athletes. The present study may be useful as comparison basis for future studies aiming evaluate the isokinetic

Dynamics of muscle strength improvement during isokinetic rehabilitation of athletes with ACL rupture and chondromalacia patellae.

Science.gov (United States)

Desnica Bakrac, N

2003-03-01

To assess quantitatively dynamics and extent of the increase in muscle strength during isokinetic rehabilitation. daily measurements of muscle strength; detailed testing at the beginning and at the end of rehabilitation. Cybex Rehabilitation Center, Zagreb. 44 athletes (31 m, 13 F, age 16-35), 3 injury-defined groups: athletes with ACL rupture (non-reconstructed and reconstructed) and chondromalacia patellae. all subjects underwent isokinetic rehabilitation on Cybex Orthotron KT2 device, using individually designed protocols (extension and flexion exercises, concentric muscle contractions, 15 treatments). monitoring of daily progress on rehabilitation device and detailed testing on diagnostic device. All patients showed considerable improvement. Muscle strength improved on average 141% (SD=110) in ACL-reconstructed group, 144% (SD=130) for chondromalacia patellae group and 150% (SD=74) for ACL-non-reconstructed group, comparing to initial strength. Dynamic status tested on Cybex Otrhotron diagnostic device prior and after rehabilitation strongly correlated with final progress monitored on the rehabilitation device. Isokinetic rehabilitation is a quick and effective method in treating knee injuries in athletes. Both types of objective criteria have shown significant increase in muscle strength. The improvement of muscle strength was on the average 149% (SD=101), which is about 10% daily for 15 treatments. The greatest progress, 19% per day, occurred during first five days. The athletes were able to resume their sport activities as follows: patients from chondromalacia patellae group, and most of them from the non-reconstructed ACL group were back in competition within a month, while 75% from the ACL reconstructed group came back within 3 months, and the rest of them within 5 months.

A New Circuit Model for Spin-Torque Oscillator Including Perpendicular Torque of Magnetic Tunnel Junction

Directory of Open Access Journals (Sweden)

Hyein Lim

2013-01-01

Full Text Available Spin-torque oscillator (STO is a promising new technology for the future RF oscillators, which is based on the spin-transfer torque (STT effect in magnetic multilayered nanostructure. It is expected to provide a larger tunability, smaller size, lower power consumption, and higher level of integration than the semiconductor-based oscillators. In our previous work, a circuit-level model of the giant magnetoresistance (GMR STO was proposed. In this paper, we present a physics-based circuit-level model of the magnetic tunnel junction (MTJ-based STO. MTJ-STO model includes the effect of perpendicular torque that has been ignored in the GMR-STO model. The variations of three major characteristics, generation frequency, mean oscillation power, and generation linewidth of an MTJ-STO with respect to the amount of perpendicular torque, are investigated, and the results are applied to our model. The operation of the model was verified by HSPICE simulation, and the results show an excellent agreement with the experimental data. The results also prove that a full circuit-level simulation with MJT-STO devices can be made with our proposed model.

40 CFR 91.306 - Dynamometer torque cell calibration.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Provisions § 91.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a force through a distance into a torque must be used in a horizontal position for horizontal shaft...

40 CFR 90.306 - Dynamometer torque cell calibration.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a force through a distance into a torque must be used in a horizontal position...

Differential Effects of 2 Rehabilitation Programs Following Anterior Cruciate Ligament Reconstruction

DEFF Research Database (Denmark)

Setuain, Igor; Izquierdo, Mikel; Idoate, Fernando

2017-01-01

in their recovery according to the current evidence-based principles. UCR group followed the national conventional approach for ACL rehabilitation. Main Outcome Measures- Concentric isokinetic knee joint flexor-extension torque assessments at 180º/s and Magnetic Resonance Imaging (MRI) evaluations were performed...

At return to play following hamstring injury the majority of professional football players have residual isokinetic deficits

NARCIS (Netherlands)

Tol, Johannes L.; Hamilton, Bruce; Eirale, Cristiano; Muxart, Patrice; Jacobsen, Philipp; Whiteley, Rod

2014-01-01

There is an ongoing debate regarding the optimal criteria for return to sport after an acute hamstring injury. Less than 10% isokinetic strength deficit is generally recommended but this has never been documented in professional football players after rehabilitation. Our aim was to evaluate

Analysis of a non-contact magnetoelastic torque transducer

International Nuclear Information System (INIS)

Andreescu, R.; Spellman, B.; Furlani, E.P.

2008-01-01

Results are presented for the performance of a magnetoelastic torque transducer that converts a torque-induced strain in a non-magnetic shaft into changes in a measurable magnetic field. The magnetic field is generated by a thin magnetostrictive layer that is coated onto the circumference of the shaft. The layer is magnetized and has an initial residual strain. The magnetization within the layer rotates in response to changes in the strain which occur when the shaft is torqued. The magnetic field produced by the layer changes with the magnetization and this can be sensed by a magnetometer to monitor the torque on the shaft. In this paper, a phenomenological theory is developed for predicting the performance of the transducer. The theory can be used to predict the magnetic field distribution of the transducer as a function of the physical properties of the magnetic coating, its residual strain, and the applied torque. It enables rapid parametric analysis of transducer performance, which is useful for the development and optimization of novel non-contact torque sensors

Multi-digit maximum voluntary torque production on a circular object

Science.gov (United States)

SHIM, JAE KUN; HUANG, JUNFENG; HOOKE, ALEXANDER W.; LATSH, MARK L.; ZATSIORSKY, VLADIMIR M.

2010-01-01

Individual digit-tip forces and moments during torque production on a mechanically fixed circular object were studied. During the experiments, subjects positioned each digit on a 6-dimensional force/moment sensor attached to a circular handle and produced a maximum voluntary torque on the handle. The torque direction and the orientation of the torque axis were varied. From this study, it is concluded that: (1) the maximum torque in the closing (clockwise) direction was larger than in the opening (counter clockwise) direction; (2) the thumb and little finger had the largest and the smallest share of both total normal force and total moment, respectively; (3) the sharing of total moment between individual digits was not affected by the orientation of the torque axis or by the torque direction, while the sharing of total normal force between the individual digit varied with torque direction; (4) the normal force safety margins were largest and smallest in the thumb and little finger, respectively. PMID:17454086

Spin-Stabilized Spacecrafts: Analytical Attitude Propagation Using Magnetic Torques

Directory of Open Access Journals (Sweden)

Roberta Veloso Garcia

2009-01-01

Full Text Available An analytical approach for spin-stabilized satellites attitude propagation is presented, considering the influence of the residual magnetic torque and eddy currents torque. It is assumed two approaches to examine the influence of external torques acting during the motion of the satellite, with the Earth's magnetic field described by the quadripole model. In the first approach is included only the residual magnetic torque in the motion equations, with the satellites in circular or elliptical orbit. In the second approach only the eddy currents torque is analyzed, with the satellite in circular orbit. The inclusion of these torques on the dynamic equations of spin stabilized satellites yields the conditions to derive an analytical solution. The solutions show that residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spacecraft's spin axis and the eddy currents torque causes an exponential decay of the angular velocity magnitude. Numerical simulations performed with data of the Brazilian Satellites (SCD1 and SCD2 show the period that analytical solution can be used to the attitude propagation, within the dispersion range of the attitude determination system performance of Satellite Control Center of Brazil National Research Institute.

PREFACE: The Science of Making Torque from Wind 2014 (TORQUE 2014)

Science.gov (United States)

Mann, Jakob; Bak, Christian; Bechmann, Andreas; Bingöl, Ferhat; Dellwik, Ebba; Dimitrov, Nikolay; Giebel, Gregor; Hansen, Martin O. L.; Jensen, Dorte Juul; Larsen, Gunner; Aagaard Madsen, Helge; Natarajan, Anand; Rathmann, Ole; Sathe, Ameya; Nørkær Sørensen, Jens; Nørkær Sørensen, Niels

2014-06-01

The 186 papers in this volume constitute the proceedings of the fifth Science of Making Torque from Wind conference, which is organized by the European Academy of Wind Energy (EAWE, www.eawe.eu). The conference, also called Torque 2014, is held at the Technical University of Denmark (DTU) 17-20 June 2014. The EAWE conference series started in 2004 in Delft, the Netherlands. In 2007 it was held in Copenhagen, in 2010 in Heraklion, Greece, and then in 2012 in Oldenburg, Germany. The global yearly production of electrical energy by wind turbines has grown approximately by 25% annually over the last couple of decades and covers now 2-3% of the global electrical power consumption. In order to make a significant impact on one of the large challenges of our time, namely global warming, the growth has to continue for a decade or two yet. This in turn requires research and education in wind turbine aerodynamics and wind resources, the two topics which are the main subjects of this conference. Similar to the growth in electrical power production by wind is the growth in scientific papers about wind energy. Over the last decade the number of papers has also grown by about 25% annually, and many research based companies all over the world are founded. Hence, the wind energy research community is rapidly expanding and the Torque conference series offers a good opportunity to meet and exchange ideas. We hope that the Torque 2014 will heighten the quality of the wind energy research, while the participants will enjoy each others company in Copenhagen. Many people have been involved in producing the Torque 2014 proceedings. The work by more than two hundred reviewers ensuring the quality of the papers is greatly appreciated. The timely evaluation and coordination of the reviews would not have been possible without the work of sixteen ''section editors'' all from DTU Wind Energy: Christian Bak, Andreas Bechmann, Ferhat Bingöl, Ebba Dellwik, Nikolay Dimitrov, Gregor Giebel, Martin

Study on Monitoring Rock Burst through Drill Pipe Torque

Directory of Open Access Journals (Sweden)

Zhonghua Li

2015-01-01

Full Text Available This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the analysis, a new device for testing drill pipe torque is developed and a series of experiments is performed under different conditions; the results show that drill pipe torque linearly increases with the increase of coal stress and coal strength; the faster the drilling speed, the larger the drill pipe torque, and vice versa. When monitoring rock burst by drill pipe torque method, the index of rock burst is regarded as a function in which coal stress index and coal strength index are principal variables. The results are important for the forecast of rock burst in coal mine.

FRICTION TORQUE IN THE SLIDE BEARINGS

Directory of Open Access Journals (Sweden)

BONDARENKO L. N.

2016-09-01

Full Text Available Summary. Problem statement. Until now slide bearings are used widely in engineering. But the calculation is made on obsolete method that is based on undetermined parameters such as wear of the bearing shell. It is accepted in the literature that if the shaft and liner material are homogeneous, the workpiece surface are cylindrical as they wear and contact between them occurs at all points contact arc. Research objective. The purpose of this study is determine a friction torque in the slide bearings of power-basis parameters. Conclusions. Since the friction is primarily responsible for wear of cinematic pairs “pin – liner” and “pivot – liner” slide bearings. It is shown that the friction torquesof angles wrap, that are obtained by the formulas and given in literature, are not only qualitatively but also quantitatively, namely, the calculation by literature to the formulas the friction torques are proportional to the angle wrap and the calculation by improved formulas the friction torques are inversely proportional to the angle wrap due to the reduction the normal pressure. Underreporting friction torque at large angle wrap is between 40 and 15 %. The difference in the magnitude of friction torque in the run-in and run-out cinematic pairs with real method of machining is 2...3 %, which it is possible to declare of reducing the finish of contacting surface of slide bearings.

Does external pneumatic compression treatment between bouts of overreaching resistance training sessions exert differential effects on molecular signaling and performance-related variables compared to passive recovery? An exploratory study.

Science.gov (United States)

Haun, Cody T; Roberts, Michael D; Romero, Matthew A; Osburn, Shelby C; Mobley, Christopher B; Anderson, Richard G; Goodlett, Michael D; Pascoe, David D; Martin, Jeffrey S

2017-01-01

We sought to compare the effects of external pneumatic compression (EPC) and sham when used concurrently with resistance training on performance-related outcomes and molecular measures related to recovery. Twenty (N = 20) resistance-trained male participants (aged 21.6±2.4 years) were randomized to balanced sham or EPC intervention groups. The protocol consisted of 3 consecutive days of heavy, voluminous back squat exercise followed by EPC/sham treatment (Days2-4) and 3 consecutive days of recovery (Days5-7) with EPC/sham only on Days5-6. On Day1 (PRE), and Days3-7, venipuncture, flexibility and pressure-to-pain threshold (PPT) measures were performed. Vastsus lateralis muscle tissue was biopsied at PRE, 1-h post-EPC/sham treatment on Day2 (POST1) and 24-h post-EPC/sham treatment on Day7 (POST2). Isokinetic peak torque was assessed at PRE and POST2. Peak isokinetic strength did not change from PRE to POST2 in either group. The PPT was significantly lower on Days3-6 with sham, indicating greater muscle soreness, though this was largely abolished in the EPC group. A significant decrease in flexibility with sham was observed on Day3 (+16.2±4.6% knee joint angle; P0.01). Vastus lateralis poly-ubiquitinated proteins significantly increased at the POST2 time point relative to PRE with sham (+66.6±24.6%; Pmuscle oxidative stress and proteolysis markers during recovery from heavy resistance exercise.

Magnon-mediated Dzyaloshinskii-Moriya torque in homogeneous ferromagnets

KAUST Repository

Manchon, Aurelien

2014-12-01

In thin magnetic layers with structural inversion asymmetry and spin-orbit coupling, the Dzyaloshinskii-Moriya interaction arises at the interface. When a spin-wave current jm flows in a system with a homogeneous magnetization m, this interaction produces an effective fieldlike torque of the form TFLm×(z×jm) as well as a dampinglike torque, TDLm×[(z×jm)×m], the latter only in the presence of spin-wave relaxation (z is normal to the interface). These torques mediated by the magnon flow can reorient the time-averaged magnetization direction and display a number of similarities with the torques arising from the electron flow in a magnetic two-dimensional electron gas with Rashba spin-orbit coupling. This magnon-mediated spin-orbit torque can be efficient in the case of magnons driven by a thermal gradient.

Comparison of whole-body vibration exercise and plyometric exercise to improve isokinetic muscular strength, jumping performance and balance of female volleyball players.

Science.gov (United States)

Kim, Yong-Youn; Park, Si-Eun

2016-11-01

[Purpose] The purpose of this study was to assess the effect of whole-body vibration exercise and plyometric exercise on female volleyball players. [Subjects and Methods] Subjects were randomly allocated to two exercise groups (whole-body vibration exercise group and plyometric exercise group). The exercise was conducted three times each week for 8 weeks. Isokinetic muscular strength, jumping performance, and balance were measured before starting the exercise and after finishing the 8 weeks of exercise. [Results] Measurements of isokinetic muscular strength revealed that the whole-body vibration exercise group showed significant increase after the exercise. However, the plyometric exercise group had no significant increase in lumbar flexion, extension, and knee flexion. Measurements of vertical jumping revealed that, the whole-body vibration exercise group had no significant increase after the exercise. However, the plyometric exercise group showed significant increase. Measurements of balance revealed that, the whole-body vibration exercise group showed significant increase. However, the plyometric exercise group showed no significant increase. [Conclusion] Although both whole-body vibration and plyometric exercises are effective intervention methods, the two methods have different effects on the improvement of isokinetic muscular strength, jumping performance, and balance of female volleyball players.

Interaction torque contributes to planar reaching at slow speed

Directory of Open Access Journals (Sweden)

Hoshi Fumihiko

2008-10-01

Full Text Available Abstract Background How the central nervous system (CNS organizes the joint dynamics for multi-joint movement is a complex problem, because of the passive interaction among segmental movements. Previous studies have demonstrated that the CNS predictively compensates for interaction torque (INT which is arising from the movement of the adjacent joints. However, most of these studies have mainly examined quick movements, presumably because the current belief is that the effects of INT are not significant at slow speeds. The functional contribution of INT for multijoint movements performed in various speeds is still unclear. The purpose of this study was to examine the contribution of INT to a planer reaching in a wide range of motion speeds for healthy subjects. Methods Subjects performed reaching movements toward five targets under three different speed conditions. Joint position data were recorded using a 3-D motion analysis device (50 Hz. Torque components, muscle torque (MUS, interaction torque (INT, gravity torque (G, and net torque (NET were calculated by solving the dynamic equations for the shoulder and elbow. NET at a joint which produces the joint kinematics will be an algebraic sum of torque components; NET = MUS - G - INT. Dynamic muscle torque (DMUS = MUS-G was also calculated. Contributions of INT impulse and DMUS impulse to NET impulse were examined. Results The relative contribution of INT to NET was not dependent on speed for both joints at every target. INT was additive (same direction to DMUS at the shoulder joint, while in the elbow DMUS counteracted (opposed to INT. The trajectory of reach was linear and two-joint movements were coordinated with a specific combination at each target, regardless of motion speed. However, DMUS at the elbow was opposed to the direction of elbow movement, and its magnitude varied from trial to trial in order to compensate for the variability of INT. Conclusion Interaction torque was important at

Current-induced Rashba spin orbit torque in silicene

Energy Technology Data Exchange (ETDEWEB)

Chen, Ji, E-mail: muze7777@hdu.edu.cn [Department of Mathematics, School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China); Peng, Yingzi [Department of Physics, School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China); Center for Integrated Spintronic Devices, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhou, Jie [Department of Mathematics, School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)

2017-06-15

Highlights: • The spin dynamics of a ferromagnetic layer coupled to a silicene is investigated. • The Rashba spin orbit torque is obtained and the well-known LLG equation is modified. • The explicit forms of spin orbit torques in Domain Wall and vortex is also obtained. - Abstract: We study theoretically the spin torque of a ferromagnetic layer coupled to a silicene in the presence of the intrinsic Rashba spin orbit coupling (RSOC) effect. By using gauge field method, we find that under the applied current, the RSOC can induce an effective field which will result in the spin precession of conduction electron without applying any magnetic field. We also derive the spin torques due to the RSOC, which generalize the Landau-Lifshitz-Gilbert (LLG) equation. The spin torques are related to the applied current, the carrier density and Rashba strength of the system.

Manipulating the voltage dependence of tunneling spin torques

KAUST Repository

Manchon, Aurelien

2012-10-01

Voltage-driven spin transfer torques in magnetic tunnel junctions provide an outstanding tool to design advanced spin-based devices for memory and reprogrammable logic applications. The non-linear voltage dependence of the torque has a direct impact on current-driven magnetization dynamics and on devices performances. After a brief overview of the progress made to date in the theoretical description of the spin torque in tunnel junctions, I present different ways to alter and control the bias dependence of both components of the spin torque. Engineering the junction (barrier and electrodes) structural asymmetries or controlling the spin accumulation profile in the free layer offer promising tools to design effcient spin devices.

Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

Science.gov (United States)

Markley, F. Landis; Reynolds, Reid G.; Liu, Frank X.; Lebsock, Kenneth L.

2009-01-01

Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum that the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical strategies for distributing a prescribed torque or momentum among the n wheels are presented, with special emphasis on configurations of four, five, and six wheels.

Relation between knee extensors' strength, postural stability and variability of centre of pressure displacement during gait in adult women

Directory of Open Access Journals (Sweden)

Eliza C. de Souza

2017-03-01

Full Text Available Background: It has been shown that variability of walking is related to fall risk similarly as postural control and muscle strength. Joint potential of this group of variables for fall risk assessment is promising, however research interested in relations between them is lacking. Objective: The aim of this study was to investigate the relation between knee extensors' strength, centre of pressure (COP velocity during one-leg stance and variability of COP displacement during various phases of gait cycle in middle-age women. Methods: A single group of 40 healthy women (age 56 ± 4.2 years took part in the study. For assessment of knee extensors' strength (peak torque and average work during concentric and eccentric contractions an isokinetic dynamometer was used. Mean velocity of COP during one-leg stance in anterior-posterior (AP and medial-lateral (ML directions was assessed on a force plate on a rigid surface with eyes open (two 30 s trials. Variability of COP displacement was assessed for loading response, midstance, terminal stance and preswing gait cycle phases (determined by vertical ground reaction force in AP and ML directions. It was measured by two force plates positioned in the middle of an 8 m walkway (5 trials at a self-selected speed. For statistical analysis of relationships between variables Pearson correlation was applied. Results: Our results showed significant correlations between eccentric peak torque and COP velocity in AP direction during one-leg stance, eccentric and concentric peak torque and COP variability during loading response in both ML and AP directions and during terminal stance in AP direction. Conclusion: Loading response and terminal stance seems to be more related to knee extensors' strength. Variables derived from postural stability assessment during one-leg stance are independent from variables derived from assessment of COP displacement variability during walking.

Analysis of thrust/torque signature of MOV

International Nuclear Information System (INIS)

Ryu, Ho Geun; Park, Seong Keun; Kim, Dae Woong

2001-01-01

For the evaluation of operability of MOV(Motor Operated Valve), the precision prediction of thrust/torque acting on the valve is important. In this paper, the analytical prediction method of thrust/torque was proposed. The design basis stem thrust calculation typically considers the followings: packing thrust, stem rejection load, design basis differential pressure load. In general, test results show that temperature, pressure, fluid type, and differential pressure, independently and combination, all have an effect on the friction factor. The prediction results of thrust/torque are well agreement with dynamic test results

Corotation torques in the solar nebula - the cutoff function

International Nuclear Information System (INIS)

Ward, W.R.

1989-01-01

The behavior of high-order corotation resonances in a disk of finite thickness is examined. The torque exerted at an mth-order resonance is determined by employing a vertically averaged disturbing function, and the ratio of this torque to that exerted on a cold, two-dimensional disk is identified as the so-called torque cutoff function. This function is then used to calculate contributions from the corotation torques to eccentricity variations of a perturber's orbit assumed orbiting in the disk. 11 references

Towards Scalable Strain Gauge-Based Joint Torque Sensors

Science.gov (United States)

D’Imperio, Mariapaola; Cannella, Ferdinando; Caldwell, Darwin G.; Cuschieri, Alfred

2017-01-01

During recent decades, strain gauge-based joint torque sensors have been commonly used to provide high-fidelity torque measurements in robotics. Although measurement of joint torque/force is often required in engineering research and development, the gluing and wiring of strain gauges used as torque sensors pose difficulties during integration within the restricted space available in small joints. The problem is compounded by the need for a scalable geometric design to measure joint torque. In this communication, we describe a novel design of a strain gauge-based mono-axial torque sensor referred to as square-cut torque sensor (SCTS), the significant features of which are high degree of linearity, symmetry, and high scalability in terms of both size and measuring range. Most importantly, SCTS provides easy access for gluing and wiring of the strain gauges on sensor surface despite the limited available space. We demonstrated that the SCTS was better in terms of symmetry (clockwise and counterclockwise rotation) and more linear. These capabilities have been shown through finite element modeling (ANSYS) confirmed by observed data obtained by load testing experiments. The high performance of SCTS was confirmed by studies involving changes in size, material and/or wings width and thickness. Finally, we demonstrated that the SCTS can be successfully implementation inside the hip joints of miniaturized hydraulically actuated quadruped robot-MiniHyQ. This communication is based on work presented at the 18th International Conference on Climbing and Walking Robots (CLAWAR). PMID:28820446

Effects of a low volume injury prevention program on the hamstring torque angle relationship

OpenAIRE

Naclerio Ayllón, Fernando José; Faigenbaum, Avery D.; Larumbe Zabala, Eneko; Goss-Sampson, Mark; Pérez-Bilbao, Txomin; Jiménez Gutiérrez, Alfonso; Beedie, Chris

2013-01-01

The effects of a 4-week lower body injury prevention program on knee muscle torque-angle relationship were examined in soccer players. Twenty men were randomly allocated to either a control (n = 10) or training group (n = 10). The training group underwent three training sessions per week, comprising 3 sets of 8 repetitions of one open-chain exercise (Nordic curl) and two closed-chain exercises-forward lunges on a Bosu balance trainer and eccentric single leg dead lifts. Maximal peak knee flex...

Technical Errors May Affect Accuracy of Torque Limiter in Locking Plate Osteosynthesis.

Science.gov (United States)

Savin, David D; Lee, Simon; Bohnenkamp, Frank C; Pastor, Andrew; Garapati, Rajeev; Goldberg, Benjamin A

2016-01-01

In locking plate osteosynthesis, proper surgical technique is crucial in reducing potential pitfalls, and use of a torque limiter makes it possible to control insertion torque. We conducted a study of the ways in which different techniques can alter the accuracy of torque limiters. We tested 22 torque limiters (1.5 Nm) for accuracy using hand and power tools under different rotational scenarios: hand power at low and high velocity and drill power at low and high velocity. We recorded the maximum torque reached after each torque-limiting event. Use of torque limiters under hand power at low velocity and high velocity resulted in significantly (P torque and subsequent complications. For torque limiters, the most reliable technique involves hand power at slow velocity or drill power with careful control of insertion speed until 1 torque-limiting event occurs.

Calculation of Cogging Torque in Hybrid Stepping Motors | Agber ...

African Journals Online (AJOL)

When the windings of a hybrid stepping motor are unexcited the permanent magnet's flux produces cogging torque. This torque has both desirable and undesirable features depending on the application that the motor is put into. This paper formulates an analytical method for predicting cogging torque using measured ...

A comparison of muscle stiffness and musculoarticular stiffness of the knee joint in young athletic males and females.

Science.gov (United States)

Wang, Dan; De Vito, Giuseppe; Ditroilo, Massimiliano; Fong, Daniel T P; Delahunt, Eamonn

2015-06-01

The objective of this study was to investigate the gender-specific differences in peak torque (PT), muscle stiffness (MS) and musculoarticular stiffness (MAS) of the knee joints in a young active population. Twenty-two male and twenty-two female recreational athletes participated. PT of the knee joint extensor musculature was assessed on an isokinetic dynamometer, MS of the vastus lateralis (VL) muscle was measured in both relaxed and contracted conditions, and knee joint MAS was quantified using the free oscillation technique. Significant gender differences were observed for all dependent variables. Females demonstrated less normalized PT (mean difference (MD)=0.4Nm/kg, p=0.005, η(2)=0.17), relaxed MS (MD=94.2N/m, pjoint injury incidence and prevalence in females when compared to males. Copyright © 2015 Elsevier Ltd. All rights reserved.

Isokinetic strength assessment offers limited predictive validity for detecting risk of future hamstring strain in sport: a systematic review and meta-analysis.

Science.gov (United States)

Green, Brady; Bourne, Matthew N; Pizzari, Tania

2018-03-01

To examine the value of isokinetic strength assessment for predicting risk of hamstring strain injury, and to direct future research into hamstring strain injuries. Systematic review. Database searches for Medline, CINAHL, Embase, AMED, AUSPORT, SPORTDiscus, PEDro and Cochrane Library from inception to April 2017. Manual reference checks, ahead-of-press and citation tracking. Prospective studies evaluating isokinetic hamstrings, quadriceps and hip extensor strength testing as a risk factor for occurrence of hamstring muscle strain. Independent search result screening. Risk of bias assessment by independent reviewers using Quality in Prognosis Studies tool. Best evidence synthesis and meta-analyses of standardised mean difference (SMD). Twelve studies were included, capturing 508 hamstring strain injuries in 2912 athletes. Isokinetic knee flexor, knee extensor and hip extensor outputs were examined at angular velocities ranging 30-300°/s, concentric or eccentric, and relative (Nm/kg) or absolute (Nm) measures. Strength ratios ranged between 30°/s and 300°/s. Meta-analyses revealed a small, significant predictive effect for absolute (SMD=-0.16, P=0.04, 95% CI -0.31 to -0.01) and relative (SMD=-0.17, P=0.03, 95% CI -0.33 to -0.014) eccentric knee flexor strength (60°/s). No other testing speed or strength ratio showed statistical association. Best evidence synthesis found over half of all variables had moderate or strong evidence for no association with future hamstring injury. Despite an isolated finding for eccentric knee flexor strength at slow speeds, the role and application of isokinetic assessment for predicting hamstring strain risk should be reconsidered, particularly given costs and specialised training required. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Remote calibration of torque wrenches in a hostile environment

Science.gov (United States)

Griffin, D. M.

1982-03-01

A relatively simple device is described which provides the capability for remote comparison of torque wrenches over a limited range. The device, properly used, provides calibration capability for most inch pound and foot pound range torque wrenches. For purposes of this discussion, the device itself was developed specifically for adapting an existing torque measuring system with torque wrenches in hostile environment. A gloved access port is utilized to manipulate the fixture while a viewing window and mirror are used to make visual comparisons. Click type wrenches do not require use of the mirror.

Advanced single tooth torquing plier with high precision: A clinical innovation

Directory of Open Access Journals (Sweden)

Jitendra Raghuwanshi

2017-01-01

Full Text Available Torque is the force which gives the operator control over the movements of roots of teeth in bilateral direction. There are various pliers available to apply torque in individual tooth, but none of the pliers are capable of measuring accurately the degrees of torque incorporated, so we have attempted to make a modified torquing plier to incorporate and measure the degrees of incorporated torque precisely.

Chronic pain and difficulty in relaxing postural muscles in patients with fibromyalgia and chronic whiplash associated disorders.

Science.gov (United States)

Elert, J; Kendall, S A; Larsson, B; Månsson, B; Gerdle, B

2001-06-01

To investigate if muscle tension according to the surface electromyogram (EMG) of the shoulder flexors is increased in consecutive patients with fibromyalgia (FM) or chronic whiplash associated disorders (WAD). A total of 59 consecutive patients with FM (n = 36) or chronic WAD (n = 23) performed 100 maximal isokinetic contractions combined with surface electromyography of the trapezius and infraspinatus. A randomized group of pain-free female (n = 27) subjects served as control group. Peak torque initially (Pti) and absolute and relative peak torque at endurance level (PTe, PTer) were registered as output variables, together with the EMG level of unnecessary muscle tension, i.e., the signal amplitude ratio (SAR). The patient groups had a higher level of unnecessary tension initially and at the endurance level. The patients had lower absolute output (PTi and PTe), but the relative levels (PTer) did not differ comparing all 3 groups. Subjects with FM had significantly higher body mass index (BMI) than the other groups. BMI did not influence the SAR but correlated positively with PTi. The results confirmed earlier findings that groups of patients with chronic pain have increased muscle tension and decreased output during dynamic activity compared to pain-free controls. However, the results indicated there is heterogeneity within groups of patients with the same chronic pain disorder and that not all patients with chronic pain have increased muscle tension.

Learning effect of isokinetic measurements in healthy subjects, and reliability and comparability of Biodex and Lido dynamometers

DEFF Research Database (Denmark)

Lund, Hans; Søndergaard, K; Zachariassen, T

2005-01-01

The aim of this study was to examine the learning effect during a set of isokinetic measurements, to evaluate the reliability of the Biodex System 3 PRO dynamometer, and to compare the Biodex System 3 PRO and the Lido Active dynamometers on both extension and flexion over the elbow and the knee a...

Direct Torque Control of Matrix Converter Fed Induction Motor Drive

Directory of Open Access Journals (Sweden)

JAGADEESAN Karpagam

2011-10-01

Full Text Available This paper presents the Direct TorqueControl (DTC of induction motor drive using matrixconverters. DTC is a high performance motor controlscheme with fast torque and flux responses. However,the main disadvantage of conventional DTC iselectromagnetic torque ripple. In this paper, directtorque control for Induction Motors using MatrixConverters is analysed and points out the problem ofthe electromagnetic torque ripple which is one of themost important drawbacks of the Direct TorqueControl. Besides, the matrix converter is a single-stageac-ac power conversion device without dc-link energystorage elements. Matrix converter (MC may becomea good alternative to voltage-source inverter (VSI.This work combines the advantages of the matrixconverter with those of the DTC technique, generatingthe required voltage vectors under unity input powerfactor operation. Simulation results demonstrates theeffectiveness of the torque control.

Static stretching vs. dynamic warm-ups: a comparison of their effects on torque and electromyography output of the quadriceps and hamstring muscles.

Science.gov (United States)

Williams, N; Coburn, J; Gillum, T

2015-11-01

The aim of this paper was to determine if two different warm-up protocols differently affect torque of the quadriceps and hamstrings, and electromyography (EMG) output of the rectus femoris (RF) and vastus lateralis (VL) when completing 30 maximal leg extensions and curls. Twenty-one healthy male (N.=8) and female (N.=13) subjects volunteered to participate in a familiarization session and three testing sessions. The three testing sessions control, dynamic, and static were completed in a counterbalanced order on non-consecutive days. First, subjects warmed-up on a treadmill for five minutes before completing six dynamic movements, six static-stretches, or no stretches. They then rested for five minutes before completing 30 maximal leg extensions and curls at a speed of 60 s-1. A significant decrease in quadriceps torque output over time was determined for the dynamic protocol when compared to the control (Phamstring torque or EMG output of the RF and VL. Short duration static-stretching has the ability to increase peak and average torque of the leg extensors, while some types of anaerobic exercise involving maximal contractions to fatigue may be hindered by performing dynamic movements as part of the warm-up.

Diffusion of torqued active particles

Science.gov (United States)

Sandoval, Mario; Lauga, Eric

2012-11-01

Motivated by swimming microorganisms whose trajectories are affected by the presence of an external torque, we calculate the diffusivity of an active particle subject to an external torque and in a fluctuating environment. The analytical results are compared with Brownian dynamics simulations showing excellent agreement between theory and numerical experiments. This work was funded in part by the Consejo Nacional de Ciencia y Tecnologia of Mexico (Conacyt postdoctoral fellowship to M. S.) and the US National Science Foundation (Grant CBET-0746285 to E.L.).

Application of Space Vector Modulation in Direct Torque Control of PMSM

Directory of Open Access Journals (Sweden)

Michal Malek

2008-01-01

Full Text Available The paper deals with an improvement of direct torque control method for permanent magnet synchronous motor drives. Electrical torque distortion of the machine under original direct torque control is relatively high and if proper measures are taken it can be substantially decreased. The proposed solution here is to combine direct torque control with the space vector modulation technique. Such approach can eliminate torque distortion while preserving the simplicity of the original method.

Intrinsic magnetic torque at low magnetic induction

International Nuclear Information System (INIS)

Doria, M.M.; Oliveira, I.G. de.

1993-01-01

Using anisotropic London theory the intrinsic magnetic torque for extreme type II uniaxial superconductors for any value of the magnetic induction is obtained. It is considered the vortex lines straight and take into account the contribution of the supercurrents flowing inside the vortex core within the London theory. It is shown that the interline and intra line free energies give opposite torque contributions, the first drives the magnetic induction parallel to the superconductor's axis of symmetry and the second orthogonal to it. At high magnetic induction torque expression obtained generalizes V. Kogan's formula since it has no free parameters other than the anisotropy γ = m 1 /m 3 and the Ginzburg-Landau parameter κ. At low magnetic induction it is proposed a way to observe vortex chains effects in the total torque based on the fact that London theory is linear and the energy to make a single vortex line in space is independent of the magnetic induction. (author)

Excitable particles in an optical torque wrench

Science.gov (United States)

Pedaci, Francesco; Huang, Zhuangxiong; van Oene, Maarten; Barland, Stephane; Dekker, Nynke H.

2011-03-01

The optical torque wrench is a laser trapping technique capable of applying and directly measuring torque on microscopic birefringent particles using spin momentum transfer, and has found application in the measurement of static torsional properties of biological molecules such as single DNAs. Motivated by the potential of the optical torque wrench to access the fast rotational dynamics of biological systems, a result of its all-optical manipulation and detection, we focus on the angular dynamics of the trapped birefringent particle, demonstrating its excitability in the vicinity of a critical point. This links the optical torque wrench to nonlinear dynamical systems such as neuronal and cardiovascular tissues, nonlinear optics and chemical reactions, all of which display an excitable binary (`all-or-none') response to input perturbations. On the basis of this dynamical feature, we devise and implement a conceptually new sensing technique capable of detecting single perturbation events with high signal-to-noise ratio and continuously adjustable sensitivity.

Low mass planet migration in magnetically torqued dead zones - II. Flow-locked and runaway migration, and a torque prescription

Science.gov (United States)

McNally, Colin P.; Nelson, Richard P.; Paardekooper, Sijme-Jan

2018-04-01

We examine the migration of low mass planets in laminar protoplanetary discs, threaded by large scale magnetic fields in the dead zone that drive radial gas flows. As shown in Paper I, a dynamical corotation torque arises due to the flow-induced asymmetric distortion of the corotation region and the evolving vortensity contrast between the librating horseshoe material and background disc flow. Using simulations of laminar torqued discs containing migrating planets, we demonstrate the existence of the four distinct migration regimes predicted in Paper I. In two regimes, the migration is approximately locked to the inward or outward radial gas flow, and in the other regimes the planet undergoes outward runaway migration that eventually settles to fast steady migration. In addition, we demonstrate torque and migration reversals induced by midplane magnetic stresses, with a bifurcation dependent on the disc surface density. We develop a model for fast migration, and show why the outward runaway saturates to a steady speed, and examine phenomenologically its termination due to changing local disc conditions. We also develop an analytical model for the corotation torque at late times that includes viscosity, for application to discs that sustain modest turbulence. Finally, we use the simulation results to develop torque prescriptions for inclusion in population synthesis models of planet formation.

Modified Direct Torque Control of Three-Phase Induction Motor Drives with Low Ripple in Flux and Torque

Directory of Open Access Journals (Sweden)

Vinay KUMAR

2011-06-01

Full Text Available This paper proposes an algorithm for direct flux and torque controlled three phase induction motor drive systems. This method is based on control of slip speed and decoupled between amplitude and angle of reference stator flux for determining required stator voltage vector. In this proposes model, integrator unit is not required to generate the reference stator flux angle for calculating required stator voltage vector, hence it eliminates the initial values problems in real time. Within the given sampling time, flux as well as torque errors are controlled by stator voltage vector which is evaluated from reference stator flux. The direct torque control is achieved by reference stator flux angle which is generates from instantaneous slip speed angular frequency and stator flux angular frequency. The amplitude of the reference stator flux is kept constant at rated value. This technique gives better performance in three-phase induction motor than conventional technique. Simulation results for 3hp induction motor drive, for both proposed and conventional techniques, are presented and compared. From the results it is found that the stator current, flux linkage and torque ripples are decreased with proposed technique.

Spin-transfer torque in spin filter tunnel junctions

KAUST Repository

Ortiz Pauyac, Christian

2014-12-08

Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green\\'s function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

Eddy Current Sensing of Torque in Rotating Shafts

Science.gov (United States)

Varonis, Orestes J.; Ida, Nathan

2013-12-01

The noncontact torque sensing in machine shafts is addressed based on the stress induced in a press-fitted magnetoelastic sleeve on the shaft and eddy current sensing of the changes of electrical conductivity and magnetic permeability due to the presence of stress. The eddy current probe uses dual drive, dual sensing coils whose purpose is increased sensitivity to torque and decreased sensitivity to variations in distance between probe and shaft (liftoff). A mechanism of keeping the distance constant is also employed. Both the probe and the magnetoelastic sleeve are evaluated for performance using a standard eddy current instrument. An eddy current instrument is also used to drive the coils and analyze the torque data. The method and sensor described are general and adaptable to a variety of applications. The sensor is suitable for static and rotating shafts, is independent of shaft diameter and operational over a large range of torques. The torque sensor uses a differential eddy current measurement resulting in cancellation of common mode effects including temperature and vibrations.

Spin-transfer torque in spin filter tunnel junctions

KAUST Repository

Ortiz Pauyac, Christian; Kalitsov, Alan; Manchon, Aurelien; Chshiev, Mairbek

2014-01-01

Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green's function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

Cogging Torque Reduction Techniques for Spoke-type IPMSM

Science.gov (United States)

Bahrim, F. S.; Sulaiman, E.; Kumar, R.; Jusoh, L. I.

2017-08-01

A spoke-type interior permanent magnet synchronous motor (IPMSM) is extending its tentacles in industrial arena due to good flux-weakening capability and high power density. In many of the application, high strength of permanent magnet causes the undesirable effects of high cogging torque that can aggravate performance of the motor. High cogging torque is significantly produced by IPMSM due to the similar length and the effectiveness of the magnetic air-gap. The address of this study is to analyze and compare the cogging torque effect and performance of four common techniques for cogging torque reduction such as skewing, notching, pole pairing and rotor pole pairing. With the aid of 3-D finite element analysis (FEA) by JMAG software, a 6S-4P Spoke-type IPMSM with various rotor-PM configurations has been designed. As a result, the cogging torque effect reduced up to 69.5% for skewing technique, followed by 31.96%, 29.6%, and 17.53% by pole pairing, axial pole pairing and notching techniques respectively.

Standard practice for torque calibration of testing machines and devices

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This practice covers procedures and requirements for the calibration of torque for static and quasi-static torque capable testing machines or devices. These may, or may not, have torque indicating systems and include those devices used for the calibration of hand torque tools. Testing machines may be calibrated by one of the three following methods or combination thereof: 1.1.1 Use of standard weights and lever arms. 1.1.2 Use of elastic torque measuring devices. 1.1.3 Use of elastic force measuring devices and lever arms. 1.1.4 Any of the methods require a specific uncertainty of measurement and a traceability derived from national standards of mass and length. 1.2 The procedures of 1.1.1, 1.1.2, and 1.1.3 apply to the calibration of the torque-indicating systems associated with the testing machine, such as a scale, dial, marked or unmarked recorder chart, digital display, etc. In all cases the buyer/owner/user must designate the torque-indicating system(s) to be calibrated and included in the repor...

Hamstring and Quadriceps Isokinetic Strength Deficits Are Weak Risk Factors for Hamstring Strain Injuries: A 4-Year Cohort Study

NARCIS (Netherlands)

van Dyk, Nicol; Bahr, Roald; Whiteley, Rodney; Tol, Johannes L.; Kumar, Bhavesh D.; Hamilton, Bruce; Farooq, Abdulaziz; Witvrouw, Erik

2016-01-01

A hamstring strain injury (HSI) has become the most common noncontact injury in soccer. Isokinetic muscle strength deficits are considered a risk factor for HSIs. However, underpowered studies with small sample sizes unable to determine small associations have led to inconclusive results regarding

Dynamics of domain wall driven by spin-transfer torque

International Nuclear Information System (INIS)

Chureemart, P.; Evans, R. F. L.; Chantrell, R. W.

2011-01-01

Spin-torque switching of magnetic devices offers new technological possibilities for data storage and integrated circuits. We have investigated domain-wall motion in a ferromagnetic thin film driven by a spin-polarized current using an atomistic spin model with a modified Landau-Lifshitz-Gilbert equation including the effect of the spin-transfer torque. The presence of the spin-transfer torque is shown to create an out-of-plane domain wall, in contrast to the external-field-driven case where an in-plane wall is found. We have investigated the effect of the spin torque on domain-wall displacement, domain-wall velocity, and domain-wall width, as well as the equilibration time in the presence of the spin-transfer torque. We have shown that the minimum spin-current density, regarded as the critical value for domain-wall motion, decreases with increasing temperature.

Spin current and spin transfer torque in ferromagnet/superconductor spin valves

Science.gov (United States)

Moen, Evan; Valls, Oriol T.

2018-05-01

Using fully self-consistent methods, we study spin transport in fabricable spin valve systems consisting of two magnetic layers, a superconducting layer, and a spacer normal layer between the ferromagnets. Our methods ensure that the proper relations between spin current gradients and spin transfer torques are satisfied. We present results as a function of geometrical parameters, interfacial barrier values, misalignment angle between the ferromagnets, and bias voltage. Our main results are for the spin current and spin accumulation as functions of position within the spin valve structure. We see precession of the spin current about the exchange fields within the ferromagnets, and penetration of the spin current into the superconductor for biases greater than the critical bias, defined in the text. The spin accumulation exhibits oscillating behavior in the normal metal, with a strong dependence on the physical parameters both as to the structure and formation of the peaks. We also study the bias dependence of the spatially averaged spin transfer torque and spin accumulation. We examine the critical-bias effect of these quantities, and their dependence on the physical parameters. Our results are predictive of the outcome of future experiments, as they take into account imperfect interfaces and a realistic geometry.

Drag and Torque on Locked Screw Propeller

Directory of Open Access Journals (Sweden)

Tomasz Tabaczek

2014-09-01

Full Text Available Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades. The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.

Spin-Orbit Torques in Co/Pd Multilayer Nanowires

KAUST Repository

Jamali, Mahdi; Narayanapillai, Kulothungasagaran; Qiu, Xuepeng; Loong, Li Ming; Manchon, Aurelien; Yang, Hyunsoo

2013-01-01

Current induced spin-orbit torques have been studied in ferromagnetic nanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic anisotropy. Using Hall voltage and lock-in measurements, it is found that upon injection of an electric current both in-plane (Slonczewski-like) and perpendicular (fieldlike) torques build up in the nanowire. The torque efficiencies are found to be as large as 1.17 and 5 kOe at 108  A/cm2 for the in-plane and perpendicular components, respectively, which is surprisingly comparable to previous studies in ultrathin (∼1  nm) magnetic bilayers. We show that this result cannot be explained solely by spin Hall effect induced torque at the outer interfaces, indicating a probable contribution of the bulk of the Co/Pd multilayer.

Spin-Orbit Torques in Co/Pd Multilayer Nanowires

KAUST Repository

Jamali, Mahdi

2013-12-09

Current induced spin-orbit torques have been studied in ferromagnetic nanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic anisotropy. Using Hall voltage and lock-in measurements, it is found that upon injection of an electric current both in-plane (Slonczewski-like) and perpendicular (fieldlike) torques build up in the nanowire. The torque efficiencies are found to be as large as 1.17 and 5 kOe at 108  A/cm2 for the in-plane and perpendicular components, respectively, which is surprisingly comparable to previous studies in ultrathin (∼1  nm) magnetic bilayers. We show that this result cannot be explained solely by spin Hall effect induced torque at the outer interfaces, indicating a probable contribution of the bulk of the Co/Pd multilayer.

Current induced torques and interfacial spin-orbit coupling: Semiclassical modeling

KAUST Repository

Haney, Paul M.

2013-05-07

In bilayer nanowires consisting of a ferromagnetic layer and a nonmagnetic layer with strong spin-orbit coupling, currents create torques on the magnetization beyond those found in simple ferromagnetic nanowires. The resulting magnetic dynamics appear to require torques that can be separated into two terms, dampinglike and fieldlike. The dampinglike torque is typically derived from models describing the bulk spin Hall effect and the spin transfer torque, and the fieldlike torque is typically derived from a Rashba model describing interfacial spin-orbit coupling. We derive a model based on the Boltzmann equation that unifies these approaches. We also consider an approximation to the Boltzmann equation, the drift-diffusion model, that qualitatively reproduces the behavior, but quantitatively differs in some regimes. We show that the Boltzmann equation with physically reasonable parameters can match the torques for any particular sample, but in some cases, it fails to describe the experimentally observed thickness dependencies.

Spin-torque generation in topological insulator based heterostructures

KAUST Repository

Fischer, Mark H.; Vaezi, Abolhassan; Manchon, Aurelien; Kim, Eun-Ah

2016-01-01

Heterostructures utilizing topological insulators exhibit a remarkable spin-torque efficiency. However, the exact origin of the strong torque, in particular whether it stems from the spin-momentum locking of the topological surface states or rather

Robust spin transfer torque in antiferromagnetic tunnel junctions

KAUST Repository

Saidaoui, Hamed Ben Mohamed; Waintal, Xavier; Manchon, Aurelien

2017-01-01

We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque

Acute Postexercise Time Course Responses of Hypertrophic vs. Power-Endurance Squat Exercise Protocols on Maximal and Rapid Torque of the Knee Extensors.

Science.gov (United States)

Conchola, Eric C; Thiele, Ryan M; Palmer, Ty B; Smith, Doug B; Thompson, Brennan J

2015-05-01

The aim of this study was to examine the effects of a medium-intensity high-volume vs. explosive squat protocol on the postexercise time course responses of maximal and rapid strength of the knee extensors. Seventeen resistance-trained men (mean ± SD: age = 22.0 ± 2.6 years) performed maximal voluntary contractions (MVCs) of the knee extensors before and after performing a squat workout using either a low-intensity fast velocity (LIFV) (5 × 16 at 40% 1 repetition maximum) or a traditional high-intensity slow velocity (TISV) (5 × 8 at 80% 1RM) exercise protocol. For each MVC, peak torque (PT), peak rate of torque development (RTDpeak), absolute (RTDabs), and relative RTD (RTDnorm) at early (0-50 milliseconds) and late (100-200 milliseconds) phases of muscle contraction were examined at pre- (Pre) and post-exercise at 0, 7, 15, and 30 (Post0...30) minutes. There were no intensity × time interactions for any variables (p = 0.098-0.832). Peak torque was greater at Pre than Post0 and Post7 (p = 0.001-0.016) but was not greater than Post15 and Post30 (p = 0.010-0.189). RTDpeak and early absolute RTD (RTD50abs) were greater at Pre than all postexercise time phases (p = 0.001-0.050); however, later absolute RTD (RTD100-200abs) was only greater at Pre than Post0 and Post30 (p = 0.013-0.048). Early relative RTD (RTD50norm) was only higher at Pre compared with Post0 (p = 0.023), whereas no differences were observed for later relative RTD (RTD100-200norm) (p = 0.920-0.990). Low-intensity fast velocity and TISV squat protocols both yielded acute decreases in maximal and rapid strength capacities following free-weight squats, with rapid strength showing slower recovery characteristics than maximal strength.

THE MID - TERM EFFECT OF KINESIO TAPING ON PEAK POWER OF QUADRICEPS AND HAMSTRING MUSCLES AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Directory of Open Access Journals (Sweden)

Amel Khabazan Mahdi

2017-01-01

Full Text Available Purpose: The aim of this study was to assess mid- term effect of Kinesio tape on peak power of quadriceps and hamstrings muscles after ACL reconstruction 24 hours after taping. Material: Thirty six men who had undergone ACL reconstruction and completed physiotherapy periods (6 months were assigned to no taping, placebo and taping groups. Peak power was tested before and 24 hours after taping by Isokinetic dynamometry. Data was analyzed by SPSS software 19. ANOVA and post hoc test (LSD were used for interpretive analysis. Results: The results showed that the effect of Kinesio tape on peak power of quadriceps muscles at velocities of 180°/s and 300°/s was significant. In the hamstring muscles, significant effects were obtained at velocities of 60°/s, 180°/s & 300°/s. Conclusion: Positive impacts of Kinesio tape on muscular peak power among athletes who had ACL reconstruction were observed. Regardless of psychological effect and reducing re - injury fear, Kinesio - tape causes to stabilize and increase effective range of motion of the knee, so it is recommended that in the explosive training, athletes who have ACL reconstruction should use tape to reduce the probability of re-injury and increase muscle power.

How joint torques affect hamstring injury risk in sprinting swing-stance transition.

Science.gov (United States)

Sun, Yuliang; Wei, Shutao; Zhong, Yunjian; Fu, Weijie; Li, Li; Liu, Yu

2015-02-01

The potential mechanisms of hamstring strain injuries in athletes are not well understood. The study, therefore, was aimed at understanding hamstring mechanics by studying loading conditions during maximum-effort overground sprinting. Three-dimensional kinematics and ground reaction force data were collected from eight elite male sprinters sprinting at their maximum effort. Maximal isometric torques of the hip and knee were also collected. Data from the sprinting gait cycle were analyzed via an intersegmental dynamics approach, and the different joint torque components were calculated. During the initial stance phase, the ground reaction force passed anteriorly to the knee and hip, producing an extension torque at the knee and a flexion torque at the hip joint. Thus, the active muscle torque functioned to produce flexion torque at the knee and extension torque at the hip. The maximal muscle torque at the knee joint was 1.4 times the maximal isometric knee flexion torque. During the late swing phase, the muscle torque counterbalanced the motion-dependent torque and acted to flex the knee joint and extend the hip joint. The loading conditions on the hamstring muscles were similar to those of the initial stance phase. During both the initial stance and late swing phases, the large passive torques at both the knee and hip joints acted to lengthen the hamstring muscles. The active muscle torques generated mainly by the hamstrings functioned to counteract those passive effects. As a result, during sprinting or high-speed locomotion, the hamstring muscles may be more susceptible to high risk of strain injury during these two phases.

Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals

KAUST Repository

Li, Hang; Wang, Xuhui; Manchon, Aurelien

2016-01-01

We study spin-orbit torques in two-dimensional hexagonal crystals such as graphene, silicene, germanene, and stanene. The torque possesses two components, a fieldlike term due to inverse spin galvanic effect and an antidamping torque originating from Berry curvature in mixed spin-k space. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. The valley imbalance can be as high as 100% by tuning the bias voltage or magnetization angle. These findings open new venues for the development of current-driven spin-orbit torques by structural design.

Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals

KAUST Repository

Li, Hang

2016-01-11

We study spin-orbit torques in two-dimensional hexagonal crystals such as graphene, silicene, germanene, and stanene. The torque possesses two components, a fieldlike term due to inverse spin galvanic effect and an antidamping torque originating from Berry curvature in mixed spin-k space. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. The valley imbalance can be as high as 100% by tuning the bias voltage or magnetization angle. These findings open new venues for the development of current-driven spin-orbit torques by structural design.

ROLE OF HAMSTRING MUSCLES IN KNEE JOINT STABILITY PROVIDING AND INJURY PREVENTION

OpenAIRE

Pontaga, Inese

2016-01-01

The aim of our investigation was to determine the ratio of maximal torque values and the torques in the certain positions of range of movements (ROM) between hamstring (H) and quadriceps femoris (Q) muscles at medium and high velocity of movement in concentric (CC) and eccentric (ECC) action of hamstring muscles. The knee muscles of 15 amateur female short and middle distance runners were tested by the dynamometer system in the isokinetic movements with the angular velocity of 90º/s and 240º...

Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

Science.gov (United States)

Hernandez, Alan; Hess, Daniel P.

2016-01-01

This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

Tennis in hot and cool conditions decreases the rapid muscle torque production capacity of the knee extensors but not of the plantar flexors

Science.gov (United States)

Girard, Olivier; Racinais, Sébastien; Périard, Julien D

2014-01-01

Objectives To assess the time course of changes in rapid muscle force/torque production capacity and neuromuscular activity of lower limb muscles in response to prolonged (∼2 h) match-play tennis under heat stress. Methods The rates of torque development (RTD) and electromyographic activity (EMG; ie, root mean square) rise were recorded from 0 to 30, –50, –100 and –200 ms during brief (3–5 s) explosive maximal isometric voluntary contractions (MVC) of the knee extensors (KE) and plantar flexors (PF), along with the peak RTD within the entirety of the torque-time curve. These values were recorded in 12 male tennis players before (prematch) and after (postmatch, 24 and 48 h) match-play in HOT (∼37°C) and COOL (∼22°C) conditions. Results The postmatch core temperature was greater in the HOT (∼39.4°C) vs COOL (∼38.7°C) condition (ptorque. Furthermore, the rate of KE EMG activity rise remained unchanged. Conversely, the PF contractile RTD and rate of EMG activity rise were unaffected by the exercise or environmental conditions. Conclusions In the KE, a reduction in maximal torque production capacity following prolonged match-play tennis appears to account for the decrease in the rate of torque development, independent of environmental conditions, while remaining unchanged in the PF. PMID:24668381

Manipulating the voltage dependence of tunneling spin torques

KAUST Repository

Manchon, Aurelien

2012-01-01

Voltage-driven spin transfer torques in magnetic tunnel junctions provide an outstanding tool to design advanced spin-based devices for memory and reprogrammable logic applications. The non-linear voltage dependence of the torque has a direct impact

[Correlations Between Joint Proprioception, Muscle Strength, and Functional Ability in Patients with Knee Osteoarthritis].

Science.gov (United States)

Chen, Yoa; Yu, Yong; He, Cheng-qi

2015-11-01

To establish correlations between joint proprioception, muscle flexion and extension peak torque, and functional ability in patients with knee osteoarthritis (OA). Fifty-six patients with symptomatic knee OA were recruited in this study. Both proprioceptive acuity and muscle strength were measured using the isomed-2000 isokinetic dynamometer. Proprioceptive acuity was evaluated by establishing the joint motion detection threshold (JMDT). Muscle strength was evaluated by Max torque (Nm) and Max torque/weight (Nm/ kg). Functional ability was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index physical function (WOMAC-PF) questionnaire. Correlational analyses were performed between proprioception, muscle strength, and functional ability. A multiple stepwise regression model was established, with WOMAC-PF as dependent variable and patient age, body mass index (BMI), visual analogue scale (VAS)-score, mean grade for Kellgren-Lawrance of both knees, mean strength for quadriceps and hamstring muscles of both knees, and mean JMDT of both knees as independent variables. Poor proprioception (high JMDT) was negatively correlated with muscle strength (Pcoefficient (B) = 0.385, P<0.50 and high VAS-scale score (B=0.347, P<0.05) were significant predictors of WOMAC-PF score. Patients with poor proprioception is associated with poor muscle strength and limitation in functional ability. Patients with symptomatic OA of knees commonly endure with moderate to considerable dysfunction, which is associated with poor proprioception (high JMDT) and high VAS-scale score.

Magnon-mediated Dzyaloshinskii-Moriya torque in homogeneous ferromagnets

KAUST Repository

Manchon, Aurelien; Ndiaye, Papa Birame; Moon, Jung-Hwan; Lee, Hyun-Woo; Lee, Kyung-Jin

2014-01-01

the time-averaged magnetization direction and display a number of similarities with the torques arising from the electron flow in a magnetic two-dimensional electron gas with Rashba spin-orbit coupling. This magnon-mediated spin-orbit torque can

Reconstruction of Twist Torque in Main Parachute Risers

Science.gov (United States)

Day, Joshua D.

2015-01-01

The reconstruction of twist torque in the Main Parachute Risers of the Capsule Parachute Assembly System (CPAS) has been successfully used to validate CPAS Model Memo conservative twist torque equations. Reconstruction of basic, one degree of freedom drop tests was used to create a functional process for the evaluation of more complex, rigid body simulation. The roll, pitch, and yaw of the body, the fly-out angles of the parachutes, and the relative location of the parachutes to the body are inputs to the torque simulation. The data collected by the Inertial Measurement Unit (IMU) was used to calculate the true torque. The simulation then used photogrammetric and IMU data as inputs into the Model Memo equations. The results were then compared to the true torque results to validate the Model Memo equations. The Model Memo parameters were based off of steel risers and the parameters will need to be re-evaluated for different materials. Photogrammetric data was found to be more accurate than the inertial data in accounting for the relative rotation between payload and cluster. The Model Memo equations were generally a good match and when not matching were generally conservative.

Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers

Science.gov (United States)

Pease, Christopher; Etheridge, J.; Wijesinghe, H. S.; Pierce, C. J.; Prikockis, M. V.; Sooryakumar, R.

Chains of micro-magnetic particles are often rotated with external magnetic fields for many lab-on-a-chip technologies such as transporting beads or mixing fluids. These applications benefit from faster responses of the actuated particles. In a rotating magnetic field, the magnetization of superparamagnetic beads, created from embedded magnetic nano-particles within a polymer matrix, is largely characterized by induced dipoles mip along the direction of the field. In addition there is often a weak dipole mop that orients out-of-phase with the external rotating field. On a two-bead dimer, the simplest chain of beads, mop contributes a torque Γm in addition to the torque from mip. For dimers with beads unbound to each other, mop rotates individual beads which generate an additional hydrodynamic torque on the dimer. Whereas, mop directly torques bound dimers. Our results show that Γm significantly alters the average frequency-dependent dimer rotation rate for both bound and unbound monomers and, when mop exceeds a critical value, increases the maximum dimer rotation frequency. Models that include magnetic and hydrodynamics torques provide good agreement with the experimental findings over a range of field frequencies.

Torque control of underactuated tendon-driven fingers

Directory of Open Access Journals (Sweden)

M. E. Abdallah

2011-02-01

Full Text Available Given an underactuated tendon-driven finger, the finger posture is underdetermined and can move freely ("flop" in a region of slack tendons. This work shows that such an underactuated finger can be operated in tendon force control (rather than position control with effective performance. The force control eliminates the indeterminate slack while commanding a parameterized space of desired torques. The torque will either push the finger to the joint limits or wrap around an external object with variable torque – behavior that is sufficient for primarily gripping fingers. In addition, introducing asymmetric joint radii to the design allows the finger to command an expanded range of joint torques and to scan an expanded set of external surfaces. This study is motivated by the design and control of the secondary fingers of the NASA-GM R2 humanoid hand.

This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

How Joint Torques Affect Hamstring Injury Risk in Sprinting Swing–Stance Transition

Science.gov (United States)

SUN, YULIANG; WEI, SHUTAO; ZHONG, YUNJIAN; FU, WEIJIE; LI, LI; LIU, YU

2015-01-01

ABSTRACT Purpose The potential mechanisms of hamstring strain injuries in athletes are not well understood. The study, therefore, was aimed at understanding hamstring mechanics by studying loading conditions during maximum-effort overground sprinting. Methods Three-dimensional kinematics and ground reaction force data were collected from eight elite male sprinters sprinting at their maximum effort. Maximal isometric torques of the hip and knee were also collected. Data from the sprinting gait cycle were analyzed via an intersegmental dynamics approach, and the different joint torque components were calculated. Results During the initial stance phase, the ground reaction force passed anteriorly to the knee and hip, producing an extension torque at the knee and a flexion torque at the hip joint. Thus, the active muscle torque functioned to produce flexion torque at the knee and extension torque at the hip. The maximal muscle torque at the knee joint was 1.4 times the maximal isometric knee flexion torque. During the late swing phase, the muscle torque counterbalanced the motion-dependent torque and acted to flex the knee joint and extend the hip joint. The loading conditions on the hamstring muscles were similar to those of the initial stance phase. Conclusions During both the initial stance and late swing phases, the large passive torques at both the knee and hip joints acted to lengthen the hamstring muscles. The active muscle torques generated mainly by the hamstrings functioned to counteract those passive effects. As a result, during sprinting or high-speed locomotion, the hamstring muscles may be more susceptible to high risk of strain injury during these two phases. PMID:24911288

High torque DC motor fabrication and test program

Science.gov (United States)

Makus, P.

1976-01-01

The testing of a standard iron and standard alnico permanent magnet two-phase, brushless dc spin motor for potential application to the space telescope has been concluded. The purpose of this study was to determine spin motor power losses, magnetic drag, efficiency and torque speed characteristics of a high torque dc motor. The motor was designed and built to fit an existing reaction wheel as a test vehicle and to use existing brass-board commutation and torque command electronics. The results of the tests are included in this report.

Predictive torque and flux control of an induction machine drive ...

Indian Academy of Sciences (India)

Finite-state model predictive control; fuzzy decision making; multi-objective optimization; predictive torque control. Abstract. Among the numerous direct torque control techniques, the finite-state predictive torque control (FS-PTC) has emerged as a powerful alternative as it offers the fast dynamic response and the flexibility to ...

Electrode position markedly affects knee torque in tetanic, stimulated contractions.

Science.gov (United States)

Vieira, Taian M; Potenza, Paolo; Gastaldi, Laura; Botter, Alberto

2016-02-01

The purpose of this study was to investigate how much the distance between stimulation electrodes affects the knee extension torque in tetanic, electrically elicited contractions. Current pulses of progressively larger amplitude, from 0 mA to maximally tolerated intensities, were delivered at 20 pps to the vastus medialis, rectus femoris and vastus lateralis muscles of ten, healthy male subjects. Four inter-electrode distances were tested: 32.5% (L1), 45.0% (L2), 57.5% (L3) and 70% (L4) of the distance between the patella apex and the anterior superior iliac spine. The maximal knee extension torque and the current leading to the maximal torque were measured and compared between electrode configurations. The maximal current tolerated by each participant ranged from 60 to 100 mA and did not depend on the inter-electrode distance. The maximal knee extension torque elicited did not differ between L3 and L4 (P = 0.15) but, for both conditions, knee torque was significantly greater than for L1 and L2 (P torque elicited for L3 and L4 was two to three times greater than that obtained for L1 and L2. The current leading to maximal torque was not as sensitive to inter-electrode distance. Except for L1 current intensity did not change with electrode configuration (P > 0.16). Key results presented here revealed that for a given stimulation intensity, knee extension torque increased dramatically with the distance between electrodes. The distance between electrodes seems therefore to critically affect knee torque, with potential implication for optimising exercise protocols based on electrical stimulation.

Towards measuring quantum electrodynamic torque with a levitated nanorod

Science.gov (United States)

Xu, Zhujing; Bang, Jaehoon; Ahn, Jonghoon; Hoang, Thai M.; Li, Tongcang

2017-04-01

According to quantum electrodynamics, quantum fluctuations of electromagnetic fields give rise to a zero-point energy that never vanishes, even in the absence of electromagnetic sources. The interaction energy will not only lead to the well-known Casimir force but will also contribute to the Casimir torque for anisotropic materials. We propose to use an optically levitated nanorod in vacuum and a birefringent substrate to experimentally investigate the QED torque. We have previously observed the libration of an optically levitated non-spherical nanoparticle in vacuum and found it to be an ultrasensitive torque sensor. A nanorod with a long axis of 300nm and a diameter of 60nm levitated in vacuum at 10 (- 8) torr will have a remarkable torque detection sensitivity on the order of 10 (- 28) Nm/ √Hz, which will be sufficient to detect the Casimir torque. This work is partially supported by the National Science Foundation under Grant No.1555035-PHY.

Direct shaft torque measurements in a transient turbine facility

International Nuclear Information System (INIS)

Beard, Paul F; Povey, Thomas

2011-01-01

This paper describes the development and implementation of a shaft torque measurement system for the Oxford Turbine Research Facility (formerly the Turbine Test Facility (TTF) at QinetiQ, Farnborough), or OTRF. As part of the recent EU TATEF II programme, the facility was upgraded to allow turbine efficiency measurements to be performed. A shaft torque measurement system was developed as part of this upgrade. The system is unique in that, to the authors' knowledge, it provided the first direct measurement of shaft torque in a transient turbine facility although the system has wider applicability to rotating test facilities in which power measurement is a requirement. The adopted approach removes the requirement to quantify bearing friction, which can be difficult to accurately calibrate under representative operating conditions. The OTRF is a short duration (approximately 0.4 s run time) isentropic light-piston facility capable of matching all of the non-dimensional parameters important for aerodynamic and heat studies, namely Mach number, Reynolds number, non-dimensional speed, stage pressure ratio and gas-to-wall temperature ratio. The single-stage MT1 turbine used for this study is a highly loaded unshrouded design, and as such is relevant to modern military, or future civil aero-engine design. Shaft torque was measured directly using a custom-built strain gauge-based torque measurement system in the rotating frame of reference. This paper describes the development of this measurement system. The system was calibrated, including the effects of temperature, to a traceable primary standard using a purpose-built facility. The bias and precision uncertainties of the measured torque were ±0.117% and ±0.183%, respectively. To accurately determine the shaft torque developed by a turbine in the OTRF, small corrections due to inertial torque (associated with changes in the rotational speed) and aerodynamic drag (windage) are required. The methods for performing these

Heat Control via Torque Control in Friction Stir Welding

Science.gov (United States)

Venable, Richard; Colligan, Kevin; Knapp, Alan

2004-01-01

In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

Hip abduction-adduction strength and one-leg hop tests: test-retest reliability and relationship to function in elite ice hockey players.

Science.gov (United States)

Kea, J; Kramer, J; Forwell, L; Birmingham, T

2001-08-01

Single group, test-retest. To determine: (1) hip abduction and adduction torques during concentric and eccentric muscle actions, (2) medial and lateral one-leg hop distances, (3) the test-retest reliability of these measurements, and (4) the relationship between isokinetic measures of hip muscle strength and hop distances in elite ice hockey players. The skating motion used in ice hockey requires strong contractions of the hip and knee musculature. However, baseline scores for hip strength and hop distances, their test-retest reliability, and measures of the extent to which these tests are related for this population are not available. The dominant leg of 27 men (mean age 20 +/- 3 yrs) was tested on 2 occasions. Hip abduction and adduction movements were completed at 60 degrees.s(-1) angular velocity, with the subject lying on the non-test side and the test leg moving vertically in the subject's coronal plane. One-leg hops requiring jumping from and landing on the same leg without losing balance were completed in the medial and lateral directions. Hip adduction torques were significantly greater than abduction torques during both concentric and eccentric muscle actions, while no significant difference was observed between medial and lateral hop distances. Although hop test scores produced excellent ICCs (> 0.75) when determined using scores on 1 occasion, torques needed to be averaged over 2 test occasions to reach this level. Correlations between the strength and hop tests ranged from slight to low (r = -0.26 to 0.27) and were characterized by wide 95% confidence intervals (-0.54 to 0.61). Isokinetic tests of hip abduction and adduction did not provide a strong indication of performance during sideways hop tests. Although isokinetic tests can provide a measure of muscular strength under specific test conditions, they should not be relied upon as a primary indicator of functional abilities or readiness to return to activity.

Anomalous magnetic torque in the heavy-fermion superconductor UBe13

International Nuclear Information System (INIS)

Schmiedeshoff, G.M.; Fisk, Z.; Smith, J.L.

1994-01-01

Measurements of the magnetic torque acting upon a single crystal of the heavy-fermion superconductor UBe 13 have been made at temperatures from 0.5 K to 30.0 K and in magnetic fields to 23 T using a capacitive magnetometer. We find that a large, anomalous contribution to the magnetic torque appears in at low temperatures and in high fields. The anomalous torque coexists with the superconducting state at low temperature. We propose that the anomalous torque reflects the existence of a field-induced magnetic phase transition. (orig.)

Smooth torque speed characteristic of switched reluctance motors

DEFF Research Database (Denmark)

Zeng, Hui; Chen, Zhe; Chen, Hao

2014-01-01

The torque ripple of switched reluctance motors (SRMs) is the main disadvantage that limits the industrial application of these motors. Although several methods for smooth-toque operation (STO) have been proposed, STO works well only within a certain torque and speed range because...

Spin-transfer torque in tunnel junctions with ferromagnetic layer of finite thickness

International Nuclear Information System (INIS)

Wilczynski, M.

2011-01-01

Two components of the spin torque exerted on a free ferromagnetic layer of finite thickness and a half-infinite ferromagnetic electrode in single tunnel junctions have been calculated in the spin-polarized free-electron-like one-band model. It has been found that the torque oscillates with the thickness of ferromagnetic layer and can be enhanced in the junction with the special layer thickness. The bias dependence of torque components also significantly changes with layer thickness. It is non-symmetric for the normal torque, in contrast to the symmetric junctions with two identical half-infinite ferromagnetic electrodes. The asymmetry of the bias dependence of the normal component of the torque can be also observed in the junctions with different spin splitting of the electron bands in the ferromagnetic electrodes. - Research highlights: → The torque oscillates with the thickness of ferromagnetic layer. → Bias dependence of the torque changes with the layer thickness. → Bias dependence of the normal torque can be asymmetric.

Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes