Neuro-mechanical determinants of repeated treadmill sprints - Usefulness of an ‘hypoxic to normoxic recovery’ approach

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Olivier eGIRARD

2015-09-01

Full Text Available To improve our understanding of the limiting factors during repeated sprinting, we manipulated hypoxia severity during an initial set and examined the effects on performance and associated neuro-mechanical alterations during a subsequent set performed in normoxia. On separate days, thirteen active males performed eight 5-s sprints (recovery = 25 s on an instrumented treadmill in either normoxia near sea-level (SL; FiO2 = 20.9%, moderate (MH; FiO2 = 16.8% or severe normobaric hypoxia (SH; FiO2 = 13.3% followed, 6 min later, by four 5-s sprints (recovery = 25 s in normoxia. Throughout the first set, along with distance covered [larger sprint decrement score in SH (-8.2% compared to SL (-5.3% and MH (-7.2%; P<0.05], changes in contact time, step frequency and root mean square activity (surface electromyography of the quadriceps (rectus femoris muscle in SH exceeded those in SL and MH (P<0.05. During first sprint of the subsequent normoxic set, the distance covered (99.6%, 96.4% and 98.3% of sprint 1 in SL, MH and SH, respectively, the main kinetic (mean, horizontal and resultant forces and kinematic (contact time and step frequency variables as well as surface electromyogram of quadriceps and plantar flexor muscles were fully recovered, with no significant difference between conditions. Despite differing hypoxic severity levels during sprints 1 to 8, performance and neuro-mechanical patterns did not differ during the four sprints of the second set performed in normoxia. In summary, under the circumstances of this study (participant background, exercise-to-rest ratio, hypoxia exposure, sprint mechanical performance and neural alterations were largerly influenced by the hypoxia severity in an initial set of repeated sprints. However, hypoxia had no residual effect during a subsequent set performed in normoxia. Hence, the recovery of performance and associated neuro-mechanical alterations was complete after resting for 6 min near sea level, with a

Neuro-mechanical determinants of repeated treadmill sprints - Usefulness of an “hypoxic to normoxic recovery” approach

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Girard, Olivier; Brocherie, Franck; Morin, Jean-Benoit; Millet, Grégoire P.

2015-01-01

To improve our understanding of the limiting factors during repeated sprinting, we manipulated hypoxia severity during an initial set and examined the effects on performance and associated neuro-mechanical alterations during a subsequent set performed in normoxia. On separate days, 13 active males performed eight 5-s sprints (recovery = 25 s) on an instrumented treadmill in either normoxia near sea-level (SL; FiO2 = 20.9%), moderate (MH; FiO2 = 16.8%) or severe normobaric hypoxia (SH; FiO2 = 13.3%) followed, 6 min later, by four 5-s sprints (recovery = 25 s) in normoxia. Throughout the first set, along with distance covered [larger sprint decrement score in SH (−8.2%) compared to SL (−5.3%) and MH (−7.2%); P < 0.05], changes in contact time, step frequency and root mean square activity (surface electromyography) of the quadriceps (Rectus femoris muscle) in SH exceeded those in SL and MH (P < 0.05). During first sprint of the subsequent normoxic set, the distance covered (99.6, 96.4, and 98.3% of sprint 1 in SL, MH, and SH, respectively), the main kinetic (mean vertical, horizontal, and resultant forces) and kinematic (contact time and step frequency) variables as well as surface electromyogram of quadriceps and plantar flexor muscles were fully recovered, with no significant difference between conditions. Despite differing hypoxic severity levels during sprints 1–8, performance and neuro-mechanical patterns did not differ during the four sprints of the second set performed in normoxia. In summary, under the circumstances of this study (participant background, exercise-to-rest ratio, hypoxia exposure), sprint mechanical performance and neural alterations were largely influenced by the hypoxia severity in an initial set of repeated sprints. However, hypoxia had no residual effect during a subsequent set performed in normoxia. Hence, the recovery of performance and associated neuro-mechanical alterations was complete after resting for 6 min near sea level

Physiological and Biomechanical Mechanisms of Distance Specific Human Running Performance.

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Thompson, M A

2017-08-01

Running events range from 60-m sprints to ultra-marathons covering 100 miles or more, which presents an interesting diversity in terms of the parameters for successful performance. Here, we review the physiological and biomechanical variations underlying elite human running performance in sprint to ultramarathon distances. Maximal running speeds observed in sprint disciplines are achieved by high vertical ground reaction forces applied over short contact times. To create this high force output, sprint events rely heavily on anaerobic metabolism, as well as a high number and large cross-sectional area of type II fibers in the leg muscles. Middle distance running performance is characterized by intermediates of biomechanical and physiological parameters, with the possibility of unique combinations of each leading to high-level performance. The relatively fast velocities in mid-distance events require a high mechanical power output, though ground reaction forces are less than in sprinting. Elite mid-distance runners exhibit local muscle adaptations that, along with a large anaerobic capacity, provide the ability to generate a high power output. Aerobic capacity starts to become an important aspect of performance in middle distance events, especially as distance increases. In distance running events, V˙O2max is an important determinant of performance, but is relatively homogeneous in elite runners. V˙O2 and velocity at lactate threshold have been shown to be superior predictors of elite distance running performance. Ultramarathons are relatively new running events, as such, less is known about physiological and biomechanical parameters that underlie ultra-marathon performance. However, it is clear that performance in these events is related to aerobic capacity, fuel utilization, and fatigue resistance. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology 2017. This work is written by US Government employees and is in

Application of the Copenhagen Soccer Test in high-level women players - locomotor activities, physiological response and sprint performance.

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Bendiksen, Mads; Pettersen, Svein Arne; Ingebrigtsen, Jørgen; Randers, Morten B; Brito, João; Mohr, Magni; Bangsbo, Jens; Krustrup, Peter

2013-12-01

We evaluated the physiological response, sprint performance and technical ability in various phases of the Copenhagen Soccer Test for Women (CSTw) and investigated whether the locomotor activities of the CSTw were comparable to competitive match-play (CM). Physiological measurements and physical/technical assessments were performed during CSTw for eleven Norwegian high-level women soccer players. The activity pattern during CSTw and CM was monitored using the ZXY tracking system. No differences were observed between CSTw and CM with regards to total distance covered (10093±94 and 9674±191m), high intensity running (1278±67 and 1193±115m) or sprinting (422±55 and 372±46m) (p>.05). During CSTw, average HR was 85±2%HRmax with 35±2% playing time >90%HRmax. Blood lactate increased (ptest. Blood glucose was 5.4±0.3mM at rest and remained unaltered during CSTw. Sprint performance (2×20m) decreased (plocomotor activities during CSTw were comparable to that of high-level competitive match-play. The physiological demands of the CSTw were high, with no changes in heart rate, blood lactate or technical performance during the test, but a lowered sprint performance towards the end of the test. Copyright © 2013 Elsevier B.V. All rights reserved.

A Clustered Repeated-Sprint Running Protocol for Team-Sport Athletes Performed in Normobaric Hypoxia

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Jaime Morrison, Chris McLellan, Clare Minahan

2015-12-01

Full Text Available The present study compared the performance (peak speed, distance, and acceleration of ten amateur team-sport athletes during a clustered (i.e., multiple sets repeated-sprint protocol, (4 sets of 4, 4-s running sprints; i.e., RSR444 in normobaric normoxia (FiO2 = 0.209; i.e., RSN with normobaric hypoxia (FiO2 = 0.140; i.e., RSH. Subjects completed two separate trials (i. RSN, ii. RSH; randomised order between 48 h and 72 h apart on a non-motorized treadmill. In addition to performance, we examined blood lactate concentration [La-] and arterial oxygen saturation (SpO2 before, during, and after the RSR444. While there were no differences in peak speed or distance during set 1 or set 2, peak speed (p = 0.04 and 0.02, respectively and distance (p = 0.04 and 0.02, respectively were greater during set 3 and set 4 of RSN compared with RSH. There was no difference in the average acceleration achieved in set 1 (p = 0.45, set 2 (p = 0.26, or set 3 (p = 0.23 between RSN and RSH; however, the average acceleration was greater in RSN than RSH in set 4 (p < 0.01. Measurements of [La-] were higher during RSH than RSN immediately after Sprint 16 (10.2 ± 2.5 vs 8.6 ± 2.6 mM; p = 0.02. Estimations of SpO2 were lower during RSH than RSN, respectively, immediately prior to the commencement of the test (89.0 ± 2.0 vs 97.2 ± 1.5 %, post Sprint 8 (78.0 ± 6.3 vs 93.8 ± 3.6 % and post Sprint 16 (75.3 ± 6.3 vs 94.5 ± 2.5 %; all p < 0.01. In summary, the RSR444 is a practical protocol for the implementation of a hypoxic repeated-sprint training intervention into the training schedules of team-sport athletes. However, given the inability of amateur team-sport athletes to maintain performance in hypoxic (FiO2 = 0.140 conditions, the potential for specific training outcomes (i.e. speed to be achieved will be compromised, thus suggesting that the RSR444 should be used with caution.

Breaking the speed limit--comparative sprinting performance of brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta)

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Castro-Santos, Theodore; Sanz-Ronda, Francisco Javier; Ruiz-Legazpi, Jorge

2013-01-01

Sprinting behavior of free-ranging fish has long been thought to exceed that of captive fish. Here we present data from wild-caught brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta), volitionally entering and sprinting against high-velocity flows in an open-channel flume. Performance of the two species was nearly identical, with the species attaining absolute speeds > 25 body lengths·s−1. These speeds far exceed previously published observations for any salmonid species and contribute to the mounting evidence that commonly accepted estimates of swimming performance are low. Brook trout demonstrated two distinct modes in the relationship between swim speed and fatigue time, similar to the shift from prolonged to sprint mode described by other authors, but in this case occurring at speeds > 19 body lengths·s−1. This is the first demonstration of multiple modes of sprint swimming at such high swim speeds. Neither species optimized for distance maximization, however, indicating that physiological limits alone are poor predictors of swimming performance. By combining distributions of volitional swim speeds with endurance, we were able to account for >80% of the variation in distance traversed by both species.

High performance image processing of SPRINT

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DeGroot, T. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

This talk will describe computed tomography (CT) reconstruction using filtered back-projection on SPRINT parallel computers. CT is a computationally intensive task, typically requiring several minutes to reconstruct a 512x512 image. SPRINT and other parallel computers can be applied to CT reconstruction to reduce computation time from minutes to seconds. SPRINT is a family of massively parallel computers developed at LLNL. SPRINT-2.5 is a 128-node multiprocessor whose performance can exceed twice that of a Cray-Y/MP. SPRINT-3 will be 10 times faster. Described will be the parallel algorithms for filtered back-projection and their execution on SPRINT parallel computers.

Sprint cycling performance is maintained with short-term contrast water immersion.

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Crampton, David; Donne, Bernard; Egaña, Mikel; Egana, Mikel; Warmington, Stuart A

2011-11-01

Given the widespread use of water immersion during recovery from exercise, we aimed to investigate the effect of contrast water immersion on recovery of sprint cycling performance, HR and, blood lactate. Two groups completed high-intensity sprint exercise before and after a 30-min randomized recovery. The Wingate group (n = 8) performed 3 × 30-s Wingate tests (4-min rest periods). The repeated intermittent sprint group (n = 8) cycled for alternating 30-s periods at 40% of predetermined maximum power and 120% maximum power, until exhaustion. Both groups completed three trials using a different recovery treatment for each trial (balanced randomized application). Recovery treatments were passive rest, 1:1 contrast water immersion (2.5 min of cold (8°C) to 2.5 min of hot (40°C)), and 1:4 contrast water immersion (1 min of cold to 4 min of hot). Blood lactate and HR were recorded throughout, and peak power and total work for pre- and postrecovery Wingate performance and exercise time and total work for repeated sprinting were recorded. Recovery of Wingate peak power was 8% greater after 1:4 contrast water immersion than after passive rest, whereas both contrast water immersion ratios provided a greater recovery of exercise time (∼ 10%) and total work (∼ 14%) for repeated sprinting than for passive rest. Blood lactate was similar between trials. Compared with passive rest, HR initially declined more slowly during contrast water immersion but increased with each transition to a cold immersion phase. These data support contrast water immersion being effective in maintaining performance during a short-term recovery from sprint exercise. This effect needs further investigation but is likely explained by cardiovascular mechanisms, shown here by an elevation in HR upon each cold immersion.

Attentional and visual demands for sprint performance in non-fatigued and fatigued conditions: reliability of a repeated sprint test

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Diercks Ron L

2010-05-01

Full Text Available Abstract Background Physical performance measures are widely used to assess physical function, providing information about physiological and biomechanical aspects of motor performance. However they do not provide insight into the attentional and visual demands for motor performance. A figure-of-eight sprint test was therefore developed to measure the attentional and visual demands for repeated-sprint performance. The aims of the study were: 1 to assess test-retest reliability of the figure-of-eight sprint test, and 2 to study the attentional and visual demands for sprint performance in a non-fatigued and fatigued condition. Methods Twenty-seven healthy athletes were included in the study. To determine test-retest reliability, a subgroup of 19 athletes performed the figure-of-eight sprint test twice. The figure-of-eight sprint test consisted of nine 30-second sprints. The sprint test consisted of three test parts: sprinting without any restriction, with an attention-demanding task, and with restricted vision. Increases in sprint times with the attention-demanding task or restricted vision are reflective of the attentional and visual demands for sprinting. Intraclass correlation coefficients (ICCs and mean difference between test and retest with 95% confidence limits (CL were used to assess test-retest reliability. Repeated-measures ANOVA were used for comparisons between the sprint times and fatigue measurements of the test parts in both a non-fatigued and fatigued condition. Results The figure-of-eight sprint test showed good test-retest reliability, with ICCs ranging from 0.75 to 0.94 (95% CL: 0.40-0.98. Zero lay within the 95% CL of the mean differences, indicating that no bias existed between sprint performance at test and retest. Sprint times during the test parts with attention-demanding task (P = 0.01 and restricted vision (P Conclusions High ICCs and the absence of systematic variation indicate good test-retest reliability of the figure

Correlation between explosive strength, aerobic power and repeated sprint ability in elite basketball players.

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Stojanovic, M D; Ostojic, S M; Calleja-González, J; Milosevic, Z; Mikic, M

2012-08-01

The aim of this study was to examine the relationship between explosive strength and aerobic power with basketball-specific repeated sprint ability in elite male basketball players. Twenty-four elite basketball players (age 22.2±3.4 years, height 197.1±6.2 cm, weight 95.7±8.8 kg; training experience 11.0±3.1 years; mean±SD), participated in the study. Subjects performed countermovement jump (CMJ) test and incremental pseudo-ramp test protocol with measured CMJ height and VO2max, respectively. Specific repeated sprint ability (RSA) test was conducted, with total sprinting time (summation of 10 sprint times - RSAtot) and sprint decrement (fatigue index - RSAFI) calculated. Significant decrements in sprint performance from the eight 30-m sprint (Pbasketball players. It seems that coaches and strength and conditioning professionals should devote additional time for explosive strength development in elite basketball players during preparatory period to enhance RSA performance.

Significant molecular and systemic adaptations after repeated sprint training in hypoxia.

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Raphael Faiss

Full Text Available While intermittent hypoxic training (IHT has been reported to evoke cellular responses via hypoxia inducible factors (HIFs but without substantial performance benefits in endurance athletes, we hypothesized that repeated sprint training in hypoxia could enhance repeated sprint ability (RSA performed in normoxia via improved glycolysis and O(2 utilization. 40 trained subjects completed 8 cycling repeated sprint sessions in hypoxia (RSH, 3000 m or normoxia (RSN, 485 m. Before (Pre- and after (Post- training, muscular levels of selected mRNAs were analyzed from resting muscle biopsies and RSA tested until exhaustion (10-s sprint, work-to-rest ratio 1:2 with muscle perfusion assessed by near-infrared spectroscopy. From Pre- to Post-, the average power output of all sprints in RSA was increased (p<0.01 to the same extent (6% vs 7%, NS in RSH and in RSN but the number of sprints to exhaustion was increased in RSH (9.4±4.8 vs. 13.0±6.2 sprints, p<0.01 but not in RSN (9.3±4.2 vs. 8.9±3.5. mRNA concentrations of HIF-1α (+55%, carbonic anhydrase III (+35% and monocarboxylate transporter-4 (+20% were augmented (p<0.05 whereas mitochondrial transcription factor A (-40%, peroxisome proliferator-activated receptor gamma coactivator 1α (-23% and monocarboxylate transporter-1 (-36% were decreased (p<0.01 in RSH only. Besides, the changes in total hemoglobin variations (Δ[tHb] during sprints throughout RSA test increased to a greater extent (p<0.01 in RSH. Our findings show larger improvement in repeated sprint performance in RSH than in RSN with significant molecular adaptations and larger blood perfusion variations in active muscles.

Effects of coffee and caffeine anhydrous on strength and sprint performance.

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Trexler, Eric T; Smith-Ryan, Abbie E; Roelofs, Erica J; Hirsch, Katie R; Mock, Meredith G

2016-09-01

Caffeine and coffee are widely used among active individuals to enhance performance. The purpose of the current study was to compare the effects of acute coffee (COF) and caffeine anhydrous (CAF) intake on strength and sprint performance. Fifty-four resistance-trained males completed strength testing, consisting of one-rep max (1RM) and repetitions to fatigue (RTF) at 80% of 1RM for leg press (LP) and bench press (BP). Participants then completed five, 10-second cycle ergometer sprints separated by one minute of rest. Peak power (PP) and total work (TW) were recorded for each sprint. At least 48 hours later, participants returned and ingested a beverage containing CAF (300 mg flat dose; yielding 3-5 mg/kg bodyweight), COF (8.9 g; 303 mg caffeine), or placebo (PLA; 3.8 g non-caloric flavouring) 30 minutes before testing. LP 1RM was improved more by COF than CAF (p = .04), but not PLA (p = .99). Significant interactions were not observed for BP 1RM, BP RTF, or LP RTF (p > .05). There were no sprint × treatment interactions for PP or TW (p > .05). 95% confidence intervals revealed a significant improvement in sprint 1 TW for CAF, but not COF or PLA. For PLA, significant reductions were observed in sprint 4 PP, sprint 2 TW, sprint 4 TW, and average TW; significant reductions were not observed with CAF or COF. Neither COF nor CAF improved strength outcomes more than PLA, while both groups attenuated sprint power reductions to a similar degree. Coffee and caffeine anhydrous may be considered suitable pre-exercise caffeine sources for high-intensity exercise.

Muscle activity in sprinting: a review.

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Howard, Róisín M; Conway, Richard; Harrison, Andrew J

2018-03-01

The use of electromyography (EMG) is widely recognised as a valuable tool for enhancing the understanding of performance drivers and potential injury risk in sprinting. The timings of muscle activations relative to running gait cycle phases and the technology used to obtain muscle activation data during sprinting are of particular interest to scientists and coaches. This review examined the main muscles being analysed by surface EMG (sEMG), their activations and timing, and the technologies used to gather sEMG during sprinting. Electronic databases were searched using 'Electromyography' OR 'EMG' AND 'running' OR 'sprinting'. Based on inclusion criteria, 18 articles were selected for review. While sEMG is widely used in biomechanics, relatively few studies have used sEMG in sprinting due to system constraints. The results demonstrated a focus on the leg muscles, with over 70% of the muscles analysed in the upper leg. This is consistent with the use of tethered and data logging EMG systems and many sprints being performed on treadmills. Through the recent advances in wireless EMG technology, an increase in the studies on high velocity movements such as sprinting is expected and this should allow practitioners to perform the analysis in an ecologically valid environment.

Application of the Copenhagen Soccer Test in high-level women players - locomotor activities, physiological response and sprint performance

DEFF Research Database (Denmark)

Bendiksen, Mads; Pettersen, Svein Arne; Ingebrigtsen, Jørgen

2013-01-01

We evaluated the physiological response, sprint performance and technical ability in various phases of the Copenhagen Soccer Test for Women (CSTw) and investigated whether the locomotor activities of the CSTw were comparable to competitive match-play (CM). Physiological measurements and physical....../technical assessments were performed during CSTw for eleven Norwegian high-level women soccer players. The activity pattern during CSTw and CM was monitored using the ZXY tracking system. No differences were observed between CSTw and CM with regards to total distance covered (10093±94 and 9674±191m), high intensity...

Effect of Beta alanine and sodium bicarbonate supplementation on repeated-sprint performance.

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Ducker, Kagan J; Dawson, Brian; Wallman, Karen E

2013-12-01

This study aimed to investigate if combining beta alanine (BA) and sodium bicarbonate (NaHCO3) supplementation could lead to enhanced repeated-sprint performance in team-sport athletes, beyond what is possible with either supplement alone. Participants (n = 24) completed duplicate trials of a repeated-sprint test (3 sets; 6 × 20 m departing every 25 seconds, 4 minutes active recovery between sets) and were then allocated into 4 groups as follows: BA only (n = 6; 28 days BA, acute sodium chloride placebo); NaHCO3 only (n = 6; 28 days glucose placebo, acute NaHCO3); BA/NaHCO3 (n = 6; 28 days BA, acute NaHCO3); placebo only (n = 6; 28 days glucose placebo, acute sodium chloride placebo), then completed duplicate trials postsupplementation. Sodium bicarbonate alone resulted in moderate effect size (d = 0.40-0.71) and "likely" and "very likely" benefit for overall total sprint times (TST) and for each individual set and for first sprint (sets 2 and 3) and best sprint time (sets 2 and 3). Combining BA and NaHCO3 resulted in "possible" to "likely" benefits for overall TST and for sets 2 and 3. First sprint (set 3) and best sprint time (sets 2 and 3) also showed "likely" benefit after this trial. The BA and placebo groups showed no differences in performance after supplementation. In conclusion, these results indicate that supplementation with acute NaHCO3 improved repeated-sprint performance more than either a combination of NaHCO3 and BA or BA alone.

Pareto-Optimal Model Selection via SPRINT-Race.

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Zhang, Tiantian; Georgiopoulos, Michael; Anagnostopoulos, Georgios C

2018-02-01

In machine learning, the notion of multi-objective model selection (MOMS) refers to the problem of identifying the set of Pareto-optimal models that optimize by compromising more than one predefined objectives simultaneously. This paper introduces SPRINT-Race, the first multi-objective racing algorithm in a fixed-confidence setting, which is based on the sequential probability ratio with indifference zone test. SPRINT-Race addresses the problem of MOMS with multiple stochastic optimization objectives in the proper Pareto-optimality sense. In SPRINT-Race, a pairwise dominance or non-dominance relationship is statistically inferred via a non-parametric, ternary-decision, dual-sequential probability ratio test. The overall probability of falsely eliminating any Pareto-optimal models or mistakenly returning any clearly dominated models is strictly controlled by a sequential Holm's step-down family-wise error rate control method. As a fixed-confidence model selection algorithm, the objective of SPRINT-Race is to minimize the computational effort required to achieve a prescribed confidence level about the quality of the returned models. The performance of SPRINT-Race is first examined via an artificially constructed MOMS problem with known ground truth. Subsequently, SPRINT-Race is applied on two real-world applications: 1) hybrid recommender system design and 2) multi-criteria stock selection. The experimental results verify that SPRINT-Race is an effective and efficient tool for such MOMS problems. code of SPRINT-Race is available at https://github.com/watera427/SPRINT-Race.

Five Weeks of Sprint and High-Intensity Interval Training Improves Paddling Performance in Adolescent Surfers.

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Farley, Oliver R L; Secomb, Josh L; Parsonage, Joanna R; Lundgren, Lina E; Abbiss, Chris R; Sheppard, Jeremy M

2016-09-01

Farley, ORL, Secomb, JL, Parsonage, JR, Lundgren, LE, Abbiss, CR, and Sheppard, JM. Five weeks of sprint and high-intensity interval training improves paddling performance in adolescent surfers. J Strength Cond Res 30(9): 2446-2452, 2016-The purpose of our study was to examine the effects of sprint interval training (SIT; 10 seconds) and high-intensity interval training (HIT; 30 seconds) on surfing athletes paddling performance (400-m time trial and repeat-sprint paddle performance). Twenty-four competitive adolescent surfers (19 male, 5 female; age = 14.4 ± 1.3 years, mass: 50.1 ± 10.7 kg, and stature: 159.9 ± 10.3 cm) were assigned to perform either 5 weeks of SIT and HIT. Participants completed a repeated-sprint paddle ability test (RSPT, 15-m surfboard sprint paddle initiated every 40 seconds × 10 bouts) and 400-m endurance surfboard paddle time trial before and after training. High-intensity interval training decreased the total time to complete the 400 m by 15.8 ± 16.1 seconds (p = 0.03), and SIT decreased the total time to complete the RSPT by 6.5 ± 4.3 seconds (p = 0.02). Fatigue index during the RSPT (first-slowest effort) was lower after HIT and SIT (p ≤ 0.001 and p = 0.02, respectively). There were no significant differences in performance changes in the 400 m (total time) and RSPT (total time, fastest 15 m time, and peak velocity) between HIT and SIT. Our study indicates that HIT and SIT may be implemented to the training program of surfers to improve aerobic and repeat-sprint paddle ability, both of which are identified as key aspects of the sport. In addition, these findings indicate that 400-m paddle and RSPT can discriminate between aerobic and anaerobic training adaptations, with aerobic gains likely from HIT and anaerobic gains from SIT.

Effects of an In-season Plyometric Training Program on Repeated Change of Direction and Sprint Performance in the Junior Soccer Player.

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Hammami, Mehréz; Negra, Yassine; Aouadi, Ridha; Shephard, Roy J; Chelly, Mohamed Souhaiel

2016-12-01

Hammami, M, Negra, Y, Aouadi, R, Shephard, RJ, and Chelly, MS. Effects of an in-season plyometric training program on repeated change of direction and sprint performance in the junior soccer player. J Strength Cond Res 30(12): 3312-3320, 2016-We aimed to determine the gains in explosive movements of male junior soccer players induced by incorporating an 8-week plyometric training program (PTP) into a standard soccer conditioning regimen 5 months after the beginning of the competitive season. Our hypothesis was that PTP would enhance explosive movements, and thus sprint running, repeated shuttle sprint ability (RSSA), agility and the ability to make repeated changes of direction (RCOD). A group of junior soccer players were randomly divided into 2 groups: an experimental group (E, n = 15, age 15.7 ± 0.2 years) and a control group (C, n = 13, age 15.8 ± 0.2 years). The participants in E and C performed training exercises and matches together, but for an 8-week period in the latter part of the season, the experimental group replaced a part of the normal regimen (the tactical session) by a biweekly course of PTP (hurdle and drop jumps). Two familiarization sessions were held 2 weeks before definitive testing. The ability of the players was assessed by 3 agility tests (a sprint test with 180° turns, a 9-3-6-3-9 m sprint with backward and forward running, and a four 5-m sprint test with turns); 2 repeated sprint tests (RSSA and RCOD); and running times over 5-, 10-, 20-, 30-, and 40-m distances. Participants in E showed gains relative to C in sprint times (p ≤ 0.05 for 5, 10, and 20 m), and 2 of 3 the RCOD parameters (RCOD best, p ≤ 0.001; RCOD total, p ≤ 0.05). However, with the pattern of plyometric training that we adopted, and perhaps because participants were in good initial physical condition, the agility and RSSA test scores remained unchanged. Nevertheless, we conclude that our PTP can be commended to junior soccer players as a means of improving

Bases of technique of sprinting

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Valeriy Druz

2015-06-01

Full Text Available Purpose: to determine the biomechanical consistent patterns of a movement of a body providing the highest speed of sprinting. Material and Methods: the analysis of scientific and methodical literature on the considered problem, the anthropometrical characteristics of the surveyed contingent of sportsmen, the analysis of high-speed shootings of the leading runners of the world. Results: the biomechanical bases of technique of sprinting make dispersal and movement of the general center of body weight of the sportsman on a parabolic curve in a start phase taking into account the initial height of its stay in a pose of a low start. Its further movement happens on a cycloidal trajectory which is formed due to a pendulum movement of the extremities creating the lifting power which provides flight duration more in a running step, than duration of a basic phase. Conclusions: the received biomechanical regularities of technique of sprinting allow increasing the efficiency of training of sportsmen in sprinting.

Effects of sodium phosphate and caffeine ingestion on repeated-sprint ability in male athletes.

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Kopec, Benjamin J; Dawson, Brian T; Buck, Christopher; Wallman, Karen E

2016-03-01

To assess the effects of sodium phosphate (SP) and caffeine supplementation on repeated-sprint performance. Randomized, double-blind, Latin-square design. Eleven team-sport males participated in four trials: (1) SP (50mgkg(-1) of free fat-mass daily for six days) and caffeine (6mgkg(-1) ingested 1h before exercise); SP+C, (2) SP and placebo (for caffeine), (3) caffeine and placebo (for SP) and (4) placebo (for SP and caffeine). After loading, participants performed a simulated team-game circuit (STGC) consisting of 2×30min halves, with 6×20-m repeated-sprint sets performed at the start, half-time and end of the STGC. There were no interaction effects between trials for first-sprint (FS), best-sprint (BS) or total-sprint (TS) times (p>0.05). However, SP resulted in the fastest times for all sprints, as supported by moderate to large effect sizes (ES; d=0.51-0.83) and 'likely' to 'very likely' chances of benefit, compared with placebo. Compared with caffeine, SP resulted in 'possible' to 'likely' chances of benefit for FS, BS and TS for numerous sets and a 'possible' chance of benefit compared with SP+C for BS (set 2). Compared with placebo, SP+C resulted in moderate ES (d=0.50-0.62) and 'possible' to 'likely' benefit for numerous sprints, while caffeine resulted in a moderate ES (d=0.63; FS: set 3) and 'likely' chances of benefit for a number of sets. While not significant, ES and qualitative analysis results suggest that SP supplementation may improve repeated-sprint performance when compared with placebo. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Effects of Sprint Interval Training With Active Recovery vs. Endurance Training on Aerobic and Anaerobic Power, Muscular Strength, and Sprint Ability.

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Sökmen, Bülent; Witchey, Ronald L; Adams, Gene M; Beam, William C

2018-03-01

Sökmen, B, Witchey, RL, Adams, GM, and Beam, WC. Effects of sprint interval training with active recovery vs. endurance training on aerobic and anaerobic power, muscular strength, and sprint ability. J Strength Cond Res 32(3): 624-631, 2018-This study compared sprint interval training with active recovery (SITAR) to moderate-intensity endurance training (ET) in aerobic and anaerobic power, muscular strength, and sprint time results. Forty-two recreationally active adults were randomly assigned to a SITAR or ET group. Both groups trained 3× per week for 10 weeks at 75% of V[Combining Dot Above]O2max for 30 minutes weeks 1-4, with duration increasing to 35 minutes weeks 5-7 and 40 minutes weeks 8-10. While ET ran on a 400-m track without rest for the full training session, SITAR sprinted until the 200-m mark and recovered with fast walking or light jogging the second 200 m to the finish line in 3× original sprint time. Maximal oxygen consumption (V[Combining Dot Above]O2max), anaerobic treadmill run to exhaustion at 12.5 km·h at 20% incline, isokinetic leg extension and flexion strength at 60 and 300°·s, and 50 m sprint time were determined before and after training. Results showed a significant improvement (p ≤ 0.05) in absolute and relative V[Combining Dot Above]O2max, anaerobic treadmill run, and sprint time in both groups. Only SITAR showed significant improvements in isokinetic leg extension and flexion at 300°·s and decreases in body mass (p ≤ 0.05). SITAR also showed significantly greater improvement (p ≤ 0.05) over ET in anaerobic treadmill run and 50 m sprint time. These data suggest that SITAR is a time-efficient strategy to induce rapid adaptations in V[Combining Dot Above]O2max comparable to ET with added improvements in anaerobic power, isokinetic strength, and sprint time not observed with ET.

Muscle and Blood Metabolites during a Soccer Game: Implications for Sprint Performance

DEFF Research Database (Denmark)

Krustrup, Peter; Mohr, Magni; Steensberg, Adam

2006-01-01

Abstract: Purpose: To examine muscle and blood metabolites during soccer match play and relate it to possible changes in sprint performance. Methods: Thirty-one Danish fourth division players took part in three friendly games. Blood samples were collected frequently during the game, and muscle......, muscle pH, or total glycogen content. Conclusion: Sprint performance is reduced both temporarily during a game and at the end of a soccer game. The latter finding may be explained by low glycogen levels in individual muscle fibers. Blood lactate is a poor indicator of muscle lactate during soccer match...

Sled Towing Acutely Decreases Acceleration Sprint Time.

Science.gov (United States)

Wong, Megan A; Dobbs, Ian J; Watkins, Casey M; Barillas, Saldiam R; Lin, Anne; Archer, David C; Lockie, Robert G; Coburn, Jared W; Brown, Lee E

2017-11-01

Wong, MA, Dobbs, IJ, Watkins, C, Barillas, SR, Lin, A, Archer, DC, Lockie, RG, Coburn, JW, and Brown, LE. Sled towing acutely decreases acceleration sprint time. J Strength Cond Res 31(11): 3046-3051, 2017-Sled towing is a common form of overload training in sports to develop muscular strength for sprinting. This type of training leads to acute and chronic outcomes. Acute training potentially leads to postactivation potentiation (PAP), which is when subsequent muscle performance is enhanced after a preload stimulus. The purpose of this study was to determine differences between rest intervals after sled towing on acute sprint speed. Twenty healthy recreationally trained men (age = 22.3 ± 2.4 years, height = 176.95 ± 5.46 cm, mass = 83.19 ± 11.31 kg) who were currently active in a field sport twice a week for the last 6 months volunteered to participate. A maximal 30-meter (m) baseline (BL) body mass (BM) sprint was performed (with splits at 5, 10, 20, and 30 m) followed by 5 visits where participants sprinted 30 m towing a sled at 30% BM then rested for 2, 4, 6, 8, or 12 minutes. They were instructed to stand still during rest times. After the rest interval, they performed a maximal 30-m post-test BM sprint. Analysis of variance (ANOVA) revealed that post sled tow BM sprint times (4.47 ± 0.21 seconds) were less than BL times (4.55 ± 0.18 seconds) on an individualized rest interval basis. A follow-up 2 × 4 ANOVA showed that this decrease occurred only in the acceleration phase over the first 5 m (BL = 1.13 ± 0.08 seconds vs. Best = 1.08 ± 0.08 seconds), which may be the result of PAP and the complex relationship between fatigue and potentiation relative to the intensity of the sled tow and the rest interval. Therefore, coaches should test their athletes on an individual basis to determine optimal rest time after a 30-m 30% BM sled tow to enhance acute sprint speed.

Factors that Influence the Performance of Elite Sprint Cross-Country Skiers.

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Hébert-Losier, Kim; Zinner, Christoph; Platt, Simon; Stöggl, Thomas; Holmberg, Hans-Christer

2017-02-01

Sprint events in cross-country skiing are unique not only with respect to their length (0.8-1.8 km), but also in involving four high-intensity heats of ~3 min in duration, separated by a relatively short recovery period (15-60 min). Our aim was to systematically review the scientific literature to identify factors related to the performance of elite sprint cross-country skiers. Four electronic databases were searched using relevant medical subject headings and keywords, as were reference lists, relevant journals, and key authors in the field. Only original research articles addressing physiology, biomechanics, anthropometry, or neuromuscular characteristics and elite sprint cross-country skiers and performance outcomes were included. All articles meeting inclusion criteria were quality assessed. Data were extracted from each article using a standardized form and subsequently summarized. Thirty-one articles met the criteria for inclusion, were reviewed, and scored an average of 66 ± 7 % (range 56-78 %) upon quality assessment. All articles except for two were quasi-experimental, and only one had a fully-experimental research design. In total, articles comprised 567 subjects (74 % male), with only nine articles explicitly reporting their skiers' sprint International Skiing Federation points (weighted mean 116 ± 78). A similar number of articles addressed skating and classical techniques, with more than half of the investigations involving roller-skiing assessments under laboratory conditions. A range of physiological, biomechanical, anthropometric, and neuromuscular characteristics was reported to relate to sprint skiing performance. Both aerobic and anaerobic capacities are important qualities, with the anaerobic system suggested to contribute more to the performance during the first of repeated heats; and the aerobic system during subsequent heats. A capacity for high speed in all the following instances is important for the performance of sprint cross

Repeated sprint ability in young basketball players: multi-direction vs. one-change of direction (Part 1

Directory of Open Access Journals (Sweden)

Johnny ePadulo

2016-04-01

Full Text Available The aim of the present study was to examine the reliability of a novel multi-direction repeated sprint ability test (RSM; 10×(6×5-m compared with a repeated sprint ability test (RSA with one change of direction (10×(2×15-m, and the relationship of the RSM and RSA with Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1 and jump performances [squat jump (SJ and counter-movement-jump (CMJ]. Thirty-six (male, n=14, female n=22 young basketball players (age 16.0±0.9 yrs performed the RSM, RSA, Yo-Yo IR1, SJ and CMJ, and were re-tested only for RSM and RSA after one week. The absolute error of reliability (standard error of the measurement was lower than 0.212-s and 0.617-s for the time variables of the RSA and RSM test, respectively. Performance in the RSA and RSM test significantly correlated with CMJ and SJ. The best time, worst time and total time of the RSA and RSM test were negatively correlated with Yo-Yo IR1 distance. Based on these findings, consistent with previously published studies, it was concluded that the novel RSM test was valid and reliable.

A comparison of maximal squat strength and 5-, 10-, and 20-meter sprint times, in athletes and recreationally trained men.

Science.gov (United States)

Comfort, Paul; Bullock, Nathan; Pearson, Stephen J

2012-04-01

The purpose of this study was to identify whether there was a relationship between relative strength during a 1 repetition maximum (1RM) back squat and 5-, 10-, and 20-m sprint performances in both trained athletes and recreationally trained individuals. Professional rugby league players (n = 24) and recreationally trained individuals (n = 20) participated in this investigation. Twenty-meter sprint time and 1RM back squat strength, using free weights, were assessed on different days. There were no significant (p ≥ 0.05) differences between the well-trained and recreationally trained groups for 5-m sprint times. In contrast, the well-trained group's 10- and 20-m sprint times were significantly quicker (p = 0.004; p = 0.002) (1.78 + 0.06 seconds; 3.03 + 0.09 seconds) compared with the recreationally trained group (1.84 + 0.07 seconds; 3.13 + 0.11 seconds). The athletes were significantly stronger (170.63 + 21.43 kg) than the recreationally trained individuals (135.45 + 30.07 kg) (p = 0.01); however, there were no significant differences (p > 0.05) in relative strength between groups (1.78 + 0.27 kg/kg; 1.78 + 0.33 kg/kg, respectively). Significant negative correlations were found between 5-m sprint time and relative squat strength (r = -0.613, power = 0.96, p = 0.004) and between relative squat strength and 10- and 20-m sprint times in the recreationally trained group (r = -0.621, power = 0.51, p = 0.003; r = -0.604, power = 0.53, p = 0.005, respectively). These results, indicating that relative strength, are important for initial sprint acceleration in all athletes but more strongly related to sprint performance over greater distances in recreationally trained individuals.

Effects of the Nordic Hamstring exercise on sprint capacity in male football players: a randomized controlled trial.

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Ishøi, Lasse; Hölmich, Per; Aagaard, Per; Thorborg, Kristian; Bandholm, Thomas; Serner, Andreas

2018-07-01

This assessor-blinded, randomized controlled superiority trial investigated the efficacy of the 10-week Nordic Hamstring exercise (NHE) protocol on sprint performance in football players. Thirty-five amateur male players (age: 17-26 years) were randomized to a do-as-usual control group (CG; n = 17) or to 10-weeks of supervised strength training using the NHE in-season (IG; n = 18). A repeated-sprint test, consisting of 4 × 6 10 m sprints, with 15 s recovery period between sprints and 180 s between sets, was conducted to evaluate total sprint time as the primary outcome. Secondary outcomes were best 10 m sprint time (10mST) and sprint time during the last sprint (L10mST). Additionally, peak eccentric hamstring strength (ECC-P HS ) and eccentric hamstring strength capacity (ECC-CAP HS ) were measured during the NHE. Ten players were lost to follow-up, thus 25 players were analyzed (CG n = 14; IG n = 11). Between-group differences in mean changes were observed in favor of the IG for sprint performance outcomes; TST (-0.649 s, p = 0.056, d = 0.38), 10mST (-0.047 s, p = 0.005, d = 0.64) and L10mST (-0.052 s, p = 0.094, d = 0.59), and for strength outcomes; ECC-P HS (62.3 N, p = 0.006, d = 0.92), and ECC-CAP HS (951 N, p = 0.005, d = 0.95). In conclusion, the NHE showed small-to-medium improvements in sprint performance and large increases in peak eccentric hamstring strength and capacity. NCT02674919.

Postactivation Potentation Effects From Accommodating Resistance Combined With Heavy Back Squats on Short Sprint Performance.

Science.gov (United States)

Wyland, Timothy P; Van Dorin, Joshua D; Reyes, G Francis Cisco

2015-11-01

Applying accommodating resistance combined with isoinertial resistance has been demonstrated to be effective in improving neuromuscular attributes important for sport performance. The main purpose of this study was to determine whether short sprints can be acutely enhanced after several sets of back squats with or without accommodating resistance. Twenty recreationally resistance-trained males (age: 23.3 ± 4.4 years; height: 178.9 ± 6.5 cm; weight: 88.3 ± 10.8 kg) performed pre-post testing on 9.1-m sprint time. Three different interventions were implemented in randomized order between pre-post 9.1-m sprints. On 3 separate days, subjects either sat for 5 minutes (CTRL), performed 5 sets of 3 repetitions at 85% of their 1 repetition maximum (1RM) with isoinertial load (STND), or performed 5 sets of 3 repetitions at 85% of their 1RM, with 30% of the total resistance coming from elastic band tension (BAND) between pre-post 9.1-m sprint testing. Posttesting for 9.1-m sprint time occurred immediately after the last set of squats (Post-Immediate) and on every minute for 4 minutes after the last set of squats (Post-1min, Post-2min, Post-3min, and Post-4min). Repeated-measures analysis of variance statistical analyses revealed no significant changes in sprint time across posttesting times during the CTRL and STND condition. During the BAND condition, sprint time significantly decreased from Post-Immediate to Post-4min (p = 0.002). The uniqueness of accommodating resistance could create an optimal postactivation potentiation effect to increase neuromuscular performance. Coaches and athletes can implement heavy accommodating resistance exercises to their warm-up when improving acute sprint time is desired.

The Effect of Gender on Sprint Performance of 10-13 Aged Middle School Students

Directory of Open Access Journals (Sweden)

Serhat Turan

2016-04-01

Full Text Available The aim of the study was to investigate the effect of gender on the 30 m sprint performance of middle school students (10-13 ages. The study included 25 male and 25 female total 50 middle school students. The mean age of female students was found as 12,36 ± 0,48 (year, the mean body weight as 42,03 ± 3,63 (kg, and the mean height as 151,11 ±5,61 (cm, and the mean age of male students was found as 12,28 ± 0,45 (year, the mean height as 152,28 ± 5,04 (cm, and the mean body weight as 43,35 ± 1,88 (kg. The mean sprint performance of female students was calculated as 6,33 ± 0,53 seconds, and the mean sprint performance of the male students was 6,17 ± 0,47 seconds. As a result the effect of gender on sprint performance was found to be insignificant between the groups (p>0,05.

Mechanical Properties of Sprinting in Elite Rugby Union and Rugby League.

Science.gov (United States)

Cross, Matt R; Brughelli, Matt; Brown, Scott R; Samozino, Pierre; Gill, Nicholas D; Cronin, John B; Morin, Jean-Benoît

2015-09-01

To compare mechanical properties of overground sprint running in elite rugby union and rugby league athletes. Thirty elite rugby code (15 rugby union and 15 rugby league) athletes participated in this cross-sectional analysis. Radar was used to measure maximal overground sprint performance over 20 or 30 m (forwards and backs, respectively). In addition to time at 2, 5, 10, 20, and 30 m, velocity-time signals were analyzed to derive external horizontal force-velocity relationships with a recently validated method. From this relationship, the maximal theoretical velocity, external relative and absolute horizontal force, horizontal power, and optimal horizontal force for peak power production were determined. While differences in maximal velocity were unclear between codes, rugby union backs produced moderately faster split times, with the most substantial differences occurring at 2 and 5 m (ES 0.95 and 0.86, respectively). In addition, rugby union backs produced moderately larger relative horizontal force, optimal force, and peak power capabilities than rugby league backs (ES 0.73-0.77). Rugby union forwards had a higher absolute force (ES 0.77) despite having ~12% more body weight than rugby league forwards. In this elite sample, rugby union athletes typically displayed greater short-distance sprint performance, which may be linked to an ability to generate high levels of horizontal force and power. The acceleration characteristics presented in this study could be a result of the individual movement and positional demands of each code.

Push Characteristics in Wheelchair Court Sport Sprinting

NARCIS (Netherlands)

van der Slikke, Rienk M A; Berger, Monique; Bregman, Daan; Veeger, Dirkjan

2016-01-01

Short sprints are important components of most wheelchair court sports, since being faster than the opponent often determines keeping ball possession or not. Sprinting capacity is best measured during a field test, allowing the athlete to freely choose push strategies adapted to their own wheelchair

Push characteristics in wheelchair court sport sprinting

NARCIS (Netherlands)

van der Slikke, R.M.A.; Berger, Monique; Bregman, D.J.J.; Veeger, H.E.J.; van der Helm, FCT; Jansen, AJ

2016-01-01

Short sprints are important components of most wheelchair court sports, since being faster than the opponent often determines keeping ball possession or not. Sprinting capacity is best measured during a field test, allowing the athlete to freely choose push strategies adapted to their own

Effects of dry-land vs. resisted- and assisted-sprint exercises on swimming sprint performances.

Science.gov (United States)

Girold, Sébastien; Maurin, Didier; Dugué, Benoit; Chatard, Jean-Claude; Millet, Grégoire

2007-05-01

This study was undertaken to compare the effects of dry-land strength training with a combined in-water resisted- and assisted-sprint program in swimmer athletes. Twenty-one swimmers from regional to national level participated in this study. They were randomly assigned to 3 groups: the strength (S) group that was involved in a dry-land strength training program where barbells were used, the resisted- and assisted-sprint (RAS) group that got involved in a specific water training program where elastic tubes were used to generate resistance and assistance while swimming, and the control (C) group which was involved in an aerobic cycling program. During 12 weeks, the athletes performed 6 training sessions per week on separate days. All of them combined the same aerobic dominant work for their basic training in swimming and running with their specific training. Athletes were evaluated 3 times: before the training program started, after 6 weeks of training, and at the end of the training program. The outcome values were the strength of the elbow flexors and extensors evaluated using an isokinetic dynamometer, and the speed, stroke rate, stroke length, and stroke depth observed during a 50-meter sprint. No changes were observed after 6 weeks of training. At the end of the training period, we observed significant increases in swimming velocity, and strength of elbow flexors and extensors both in the S and RAS groups. However, stroke depth decreased both in the S and RAS groups. Stroke rate increased in the RAS but not in the S group. However, no significant differences in the swimming performances between the S and RAS groups were observed. No significant changes occurred in C. Altogether, programs combining swimming with dry-land strength or with in-water resisted- and assisted-sprint exercises led to a similar gain in sprint performance and are more efficient than traditional swimming training methods alone.

Comparison of sprinting vs non-sprinting to wean nasal continuous positive airway pressure off in very preterm infants.

Science.gov (United States)

Eze, N; Murphy, D; Dhar, V; Rehan, V K

2018-02-01

Though nasal continuous positive airway pressure (NCPAP) is commonly used for non-invasive neonatal respiratory support, the optimal method of weaning NCPAP is not established. In this prospective, two-center randomized control trial we hypothesize that gradually increasing spontaneous breathing time off NCPAP increases successful weaning from NCPAP in infants born 0.05). It took 1.3 (1 to 1.75) (median (IQR)) attempts and 7 (7 to 7) days to wean NCPAP off in the sprinting group vs 1.3 (1 to 1.75) attempts and 7 (7 to 10) days in the non-sprinting group (P>0.05). Additionally, no differences in the secondary outcomes of bronchopulmonary dysplasia, severe retinopathy of prematurity (⩾stage 3), periventricular leukomalacia and length of stay were noted between the two groups. Weaning NCPAP via sprinting or non-sprinting protocol is comparable, not only for successful weaning but also for the occurrence of common neonatal morbidities that impact the long-term outcome in premature infants (ClinicalTrials.gov number, NCT02819050).

Performance and Metabolic Demand of a New Repeated-Sprint Ability Test in Basketball Players: Does the Number of Changes of Direction Matter?

Science.gov (United States)

Zagatto, Alessandro M; Ardigò, Luca P; Barbieri, Fabio A; Milioni, Fabio; Dello Iacono, Antonio; Camargo, Bruno H F; Padulo, Johnny

2017-09-01

Zagatto, AM, Ardigò, LP, Barbieri, FA, Milioni, F, Dello Iacono, A, Camargo, BHF, and Padulo, J. Performance and metabolic demand of a new repeated-sprint ability test in basketball players: does the number of changes of direction matter? J Strength Cond Res 31(9): 2438-2446, 2017-This study compared 2 repeated-sprint ability (RSA) tests in basketball players. Both tests included 10 × 30-m sprints, with the difference that the previously validated test (RSA2COD) featured 2 changes of direction (COD) per sprint, whereas the experimental test (RSA5COD) featured 5 CODs per sprint. Test performances and metabolic demands were specifically assessed in 20 basketball players. First, RSA5COD test-retest reliability was investigated. Then, RSA2COD, RSA5COD sprint times, peak speeds, oxygen uptake (V[Combining Dot Above]O2) and posttest blood lactate concentration [La] were measured. The RSA5COD results showed to be reliable. RSA2COD performance resulted better than the RSA5COD version (p 0.05). Over whole bout, the RSA2COD was more demanding than the RSA5COD, considering overall metabolic power requirement (i.e., VO2-driven + [La]-driven components). Given that RSA5COD (a) mimics real game-play as sprint distance and action change frequency/direction and (b) has the same metabolic expenditure per task completion as metabolic cost, RSA5COD is a valuable option for players and coaches for training basketball-specific agility and assessing bioenergetic demands.

High-intensity sprint fatigue does not alter constant-submaximal velocity running mechanics and spring-mass behavior.

Science.gov (United States)

Morin, Jean-Benoit; Tomazin, Katja; Samozino, Pierre; Edouard, Pascal; Millet, Guillaume Y

2012-04-01

We investigated the changes in constant velocity spring-mass behavior after high intensity sprint fatigue in order to better interpret the results recently reported after ultra-long distance (ULD) exercises. Our hypothesis was that after repeated sprints (RS), subjects may likely experience losses of force such as after ULD, but the necessity to modify their running pattern to attenuate the overall impact at each step (such as after ULD) may not be present. Eleven male subjects performed four sets of five 6-s sprints with 24-s recovery between sprints and 3 min between sets, on a sprint treadmill and on a bicycle ergometer. For each session, their running mechanics and spring-mass characteristics were measured at 10 and 20 km h(-1) on an instrumented treadmill before and after RS. Two-way (period and velocity) ANOVAs showed that high-intensity fatigue did not induce any change in the constant velocity running pattern at low or high velocity, after both running and cycling RS, despite significant decreases (P < 0.001) in maximal power (-27.1 ± 8.2% after running RS and -15.4 ± 11.5 % after cycling RS) and knee extensors maximal voluntary force (-18.8 ± 6.7 % after running RS and -15.0 ± 7.6 % after cycling RS). These results bring indirect support to the hypothesis put forward in recent ULD studies that the changes in running mechanics observed after ULD are likely not related to the decrease in strength capabilities, but rather to the necessity for subjects to adopt a protective running pattern.

The recovery of repeated-sprint exercise is associated with PCr resynthesis, while muscle pH and EMG amplitude remain depressed.

Directory of Open Access Journals (Sweden)

Alberto Mendez-Villanueva

Full Text Available The physiological equivalents of power output maintenance and recovery during repeated-sprint exercise (RSE remain to be fully elucidated. In an attempt to improve our understanding of the determinants of RSE performance we therefore aimed to determine its recovery following exhaustive exercise (which affected intramuscular and neural factors concomitantly with those of intramuscular concentrations of adenosine triphosphate [ATP], phosphocreatine [PCr] and pH values and electromyography (EMG activity (a proxy for net motor unit activity changes. Eight young men performed 10, 6-s all-out sprints on a cycle ergometer, interspersed with 30 s of recovery, followed, after 6 min of passive recovery, by five 6-s sprints, again interspersed by 30 s of passive recovery. Biopsies of the vastus lateralis were obtained at rest, immediately after the first 10 sprints and after 6 min of recovery. EMG activity of the vastus lateralis was obtained from surface electrodes throughout exercise. Total work (TW, [ATP], [PCr], pH and EMG amplitude decreased significantly throughout the first ten sprints (P<0.05. After 6 min of recovery, TW during sprint 11 recovered to 86.3±7.7% of sprint 1. ATP and PCr were resynthesized to 92.6±6.0% and 85.3±10.3% of the resting value, respectively, but muscle pH and EMG amplitude remained depressed. PCr resynthesis was correlated with TW done in sprint 11 (r = 0.79, P<0.05 and TW done during sprints 11 to 15 (r = 0.67, P<0.05. There was a ∼2-fold greater decrease in the TW/EMG ratio in the last five sprints (sprint 11 to 15 than in the first five sprints (sprint 1 to 5 resulting in a disproportionate decrease in mechanical power (i.e., TW in relation to EMG. Thus, we conclude that the inability to produce power output during repeated sprints is mostly mediated by intramuscular fatigue signals probably related with the control of PCr metabolism.

Simulation of aperiodic bipedal sprinting.

Science.gov (United States)

Celik, Huseyin; Piazza, Stephen J

2013-08-01

Synthesis of legged locomotion through dynamic simulation is useful for exploration of the mechanical and control variables that contribute to efficient gait. Most previous simulations have made use of periodicity constraints, a sensible choice for investigations of steady-state walking or running. Sprinting from rest, however, is aperiodic by nature and this aperiodicity is central to the goal of the movement, as performance is determined in large part by a rapid acceleration phase early in the race. The purpose of this study was to create a novel simulation of aperiodic sprinting using a modified spring-loaded inverted pendulum (SLIP) biped model. The optimal control problem was to find the set of controls that minimized the time for the model to run 20 m, and this problem was solved using a direct multiple shooting algorithm that converts the original continuous time problem into piecewise discrete subproblems. The resulting nonlinear programming problem was solved iteratively using a sequential quadratic programming method. The starting point for the optimizer was an initial guess simulation that was a slow alternating-gait "jogging" simulation developed using proportional-derivative feedback to control trunk attitude, swing leg angle, and leg retraction and extension. The optimized aperiodic sprint simulation solution yielded a substantial improvement in locomotion time over the initial guess (2.79 s versus 6.64 s). Following optimization, the model produced forward impulses at the start of the sprint that were four times greater than those of the initial guess simulation, producing more rapid acceleration. Several gait features demonstrated in the optimized sprint simulation correspond to behaviors of human sprinters: forward trunk lean at the start; straightening of the trunk during acceleration; and a dive at the finish. Optimization resulted in reduced foot contact times (0.065 s versus 0.210 s), but contact times early in the optimized

Solar Sprint

Science.gov (United States)

Tabor, Richard; Anderson, Stephen

2007-01-01

In the "Solar Sprint" activity, students design, test, and race a solar-powered car built with Legos. The use of ratios is incorporated to simulate the actual work of scientists and engineers. This method encourages fourth-grade students to think about multiple variables and stimulates their curiosity when an activity doesn't come out as…

Does Vibration Warm-up Enhance Kinetic and Temporal Sprint Parameters?

Science.gov (United States)

Cochrane, D J; Cronin, M J; Fink, P W

2015-08-01

The aim of this study was to investigate the efficacy of vibration warm-up to enhance sprint performance. 12 males involved in representative team sports performed 4 warm-up conditions in a randomised order performed at least 24 h apart; VbX warm-up (VbX-WU); Neural activation warm-up (Neu-WU); Dynamic warm-up (Dyn-WU) and Control (No VbX). Participants completed 5 m sprint at 30 s, 2:30 min and 5 min post warm-up where sprint time, kinetics, and temporal components were recorded. There was no significant (p>0.05) main effect or interaction effect between the split sprint times of 1 m, 2.5 m, and 5 m. There was a condition effect where vertical mean force was significantly higher (p0.05) main and interaction effects in sprint kinetic and temporal parameters existed. Overall, all 4 warm-up conditions produced comparable results for sprint performance, and there was no detrimental effect on short-duration sprint performance using VbX-WU. Therefore, VbX could be useful for adding variety to the training warm-up or be included into the main warm-up routine as a supplementary modality. © Georg Thieme Verlag KG Stuttgart · New York.

A sled push stimulus potentiates subsequent 20-m sprint performance.

Science.gov (United States)

Seitz, Laurent B; Mina, Minas A; Haff, G Gregory

2017-08-01

The objective of this study was to examine the potentiating effects of performing a single sprint-style sled push on subsequent unresisted 20m sprint performance. Randomized crossover design. Following a familiarization session, twenty rugby league players performed maximal unresisted 20m sprints before and 15s, 4, 8 and 12min after a single sled push stimulus loaded with either 75 or 125% body mass. The two sled push conditions were performed in a randomized order over a one-week period. The fastest sprint time recorded before each sled push was compared to that recorded at each time point after to determine the post-activation potentiation (PAP) effect. After the 75% body mass sled push, sprint time was 0.26±1.03% slower at the 15s time point (effect size [ES]=0.07) but faster at the 4 (-0.95±2.00%; ES=-0.22), 8 (-1.80±1.43%; ES=-0.42) and 12 (-1.54±1.54%; ES=-0.36)min time points. Sprint time was slower at all the time points after the 125% body mass sled (1.36±2.36%-2.59±2.90%; ESs=0.34-0.64). Twenty-meter sprint performance is potentiated 4-12min following a sled push loaded with 75% body mass while it is impaired after a 125% body mass sled. These results are of great importance for coaches seeking to potentiate sprint performance with the sled push exercise. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Sprint performance and propulsion asymmetries on an ergometer in trained high- and low-point wheelchair rugby players.

Science.gov (United States)

Goosey-Tolfrey, V L; Vegter, R J K; Mason, B S; Paulson, T A W; Lenton, J P; van der Scheer, J W; van der Woude, L H V

2018-05-01

The purpose of this study was to examine the propulsion asymmetries of wheelchair athletes while sprinting on an instrumented, dual-roller ergometer system. Eighteen experienced wheelchair rugby players (8 low point (LP) (class ≤1.5) and 10 high point (HP) (class ≥2.0)) performed a 15-second sprint in their sports wheelchair on the instrumented ergometer. Asymmetry was defined as the difference in distance and power output (PO) between left and right sides when the best side reached 28 m. Propulsion techniques were quantified based on torque and velocity data. HP players covered an average 3 m further than the LP players (P = .002) and achieved faster sprint times than LP players (6.95 ± 0.89 vs 8.03 ± 0.68 seconds, P = .005) and at the time the best player finished (5.96 seconds). Higher peak POs (667 ± 108 vs 357 ± 78 W, P = .0001) and greater peak speeds that were also evident were for HP players (4.80 ± 0.71 vs 4.09 ± 0.45 m/s, P = .011). Greater asymmetries were found in HP players for distance (1.86 ± 1.43 vs 0.70 ± 0.65 m, P = .016), absolute peak PO (P = .049), and speed (0.35 ± 0.25 vs 0.11 ± 0.10 m/s, P = .009). Although HP players had faster sprint times over 28 m (achieved by a higher PO), high standard deviations show the heterogeneity within the two groups (eg, some LP players were better than HP players). Quantification of asymmetries is important not only for classifiers but also for sports practitioners wishing to improve performance as they could be addressed through training and/or wheelchair configuration. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effect of Different Training Methods on Stride Parameters in Speed Maintenance Phase of 100-m Sprint Running.

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Cetin, Emel; Hindistan, I Ethem; Ozkaya, Y Gul

2018-05-01

Cetin, E, Hindistan, IE, Ozkaya, YG. Effect of different training methods on stride parameters in speed maintenance phase of 100-m sprint running. J Strength Cond Res 32(5): 1263-1272, 2018-This study examined the effects of 2 different training methods relevant to sloping surface on stride parameters in speed maintenance phase of 100-m sprint running. Twenty recreationally active students were assigned into one of 3 groups: combined training (Com), horizontal training (H), and control (C) group. Com group performed uphill and downhill training on a sloping surface with an angle of 4°, whereas H group trained on a horizontal surface, 3 days a week for 8 weeks. Speed maintenance and deceleration phases were divided into distances with 10-m intervals, and running time (t), running velocity (RV), step frequency (SF), and step length (SL) were measured at preexercise, and postexercise period. After 8 weeks of training program, t was shortened by 3.97% in Com group, and 2.37% in H group. Running velocity also increased for totally 100 m of running distance by 4.13 and 2.35% in Com, and H groups, respectively. At the speed maintenance phase, although t and maximal RV (RVmax) found to be statistically unaltered during overall phase, t was found to be decreased, and RVmax was preceded by 10 m in distance in both training groups. Step length was increased at 60-70 m, and SF was decreased at 70-80 m in H group. Step length was increased with concomitant decrease in SF at 80-90 m in Com group. Both training groups maintained the RVmax with a great percentage at the speed maintenance phase. In conclusion, although both training methods resulted in an increase in running time and RV, Com training method was more prominently effective method in improving RV, and this improvement was originated from the positive changes in SL during the speed maintaining phase.

Differences in hamstring activation characteristics between the acceleration and maximum-speed phases of sprinting.

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Higashihara, Ayako; Nagano, Yasuharu; Ono, Takashi; Fukubayashi, Toru

2018-06-01

This study aimed to investigate activation characteristics of the biceps femoris long head (BFlh) and semitendinosus (ST) muscles during the acceleration and maximum-speed phases of sprinting. Lower-extremity kinematics and electromyographic (EMG) activities of the BFlh and ST muscles were examined during the acceleration sprint and maximum-speed sprint in 13 male sprinters during an overground sprinting. Differences in hamstring activation during each divided phases and in the hip and knee joint angles and torques at each time point of the sprinting gait cycle were determined between two sprints. During the early stance of the acceleration sprint, the hip extension torque was significantly greater than during the maximum-speed sprint, and the relative EMG activation of the BFlh muscle was significantly higher than that of the ST muscle. During the late stance and terminal mid-swing of maximum-speed sprint, the knee was more extended and a higher knee flexion moment was observed compared to the acceleration sprint, and the ST muscle showed higher activation than that of the BFlh. These results indicate that the functional demands of the medial and lateral hamstring muscles differ between two different sprint performances.

Sprint-based exercise and cognitive function in adolescents

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Simon B. Cooper

2016-12-01

Full Text Available Moderate intensity exercise has been shown to enhance cognition in an adolescent population, yet the effect of high-intensity sprint-based exercise remains unknown and was therefore examined in the present study. Following ethical approval and familiarisation, 44 adolescents (12.6 ± 0.6 y completed an exercise (E and resting (R trial in a counter-balanced, randomised crossover design. The exercise trial comprised of 10 × 10 s running sprints, interspersed by 50 s active recovery (walking. A battery of cognitive function tests (Stroop, Digit Symbol Substitution (DSST and Corsi blocks tests were completed 30 min pre-exercise, immediately post-exercise and 45 min post-exercise. Data were analysed using mixed effect models with repeated measures. Response times on the simple level of the Stroop test were significantly quicker 45 min following sprint-based exercise (R: 818 ± 33 ms, E: 772 ± 26 ms; p = 0.027 and response times on the complex level of the Stroop test were quicker immediately following the sprint-based exercise (R: 1095 ± 36 ms, E: 1043 ± 37 ms; p = 0.038, while accuracy was maintained. Sprint-based exercise had no immediate or delayed effects on the number of items recalled on the Corsi blocks test (p = 0.289 or substitutions made during the DSST (p = 0.689. The effect of high intensity sprint-based exercise on adolescents' cognitive function was dependant on the component of cognitive function examined. Executive function was enhanced following exercise, demonstrated by improved response times on the Stroop test, whilst visuo-spatial memory and general psycho-motor speed were unaffected. These data support the inclusion of high-intensity sprint-based exercise for adolescents during the school day to enhance cognition.

Postactivation potentiation of sprint acceleration performance using plyometric exercise.

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Turner, Anthony P; Bellhouse, Sam; Kilduff, Liam P; Russell, Mark

2015-02-01

Postactivation potentiation (PAP), an acute and temporary enhancement of muscular performance resulting from previous muscular contraction, commonly occurs after heavy resistance exercise. However, this method of inducing PAP has limited application to the precompetition practices (e.g., warm-up) of many athletes. Very few studies have examined the influence of plyometric activity on subsequent performance; therefore, we aimed to examine the influence of alternate-leg bounding on sprint acceleration performance. In a randomized crossover manner, plyometric-trained men (n = 23) performed seven 20-m sprints (with 10-m splits) at baseline, ∼15 seconds, 2, 4, 8, 12, and 16 minutes after a walking control (C) or 3 sets of 10 repetitions of alternate-leg bounding using body mass (plyometric, P) and body mass plus 10% (weighted plyometric, WP). Mean sprint velocities over 10 and 20 m were similar between trials at baseline. At ∼15 seconds, WP impaired 20-m sprint velocity by 1.4 ± 2.5% when compared with C (p = 0.039). Thereafter, 10- and 20-m sprint velocities improved in WP at 4 minutes (10 m: 2.2 ± 3.1%, p = 0.009; 20 m: 2.3 ± 2.6%, p = 0.001) and 8 minutes (10 m: 2.9 ± 3.6%, p = 0.002; 20 m: 2.6 ± 2.8%, p = 0.001) compared with C. Improved 10-m sprint acceleration performance occurred in P at 4 minutes (1.8 ± 3.3%, p = 0.047) relative to C. Therefore, sprint acceleration performance is enhanced after plyometric exercise providing adequate recovery is given between these activities; however, the effects may differ according to whether additional load is applied. This finding presents a practical method to enhance the precompetition practices of athletes.

The Effects of Muscular Fatigue on the Kinetics of Sprint Running.

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Sprague, Paul; Mann, Ralph V.

1983-01-01

To compare the kinematic and kinetic effects of fatigue on the biomechanics of sprint running, male subjects were filmed performing a short maximal exertion sprint and a long fatiguing sprint. Observable differences in the productive muscular activity of the better and the poorer sprinters occurred during the ground-phase of their strides.…

Spinal Cord Excitability and Sprint Performance Are Enhanced by Sensory Stimulation During Cycling

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Gregory E. P. Pearcey

2017-12-01

Full Text Available Spinal cord excitability, as assessed by modulation of Hoffmann (H- reflexes, is reduced with fatiguing isometric contractions. Furthermore, spinal cord excitability is reduced during non-fatiguing arm and leg cycling. Presynaptic inhibition of Ia terminals is believed to contribute to this suppression of spinal cord excitability. Electrical stimulation to cutaneous nerves reduces Ia presynaptic inhibition, which facilitates spinal cord excitability, and this facilitation is present during arm cycling. Although it has been suggested that reducing presynaptic inhibition may prolong fatiguing contractions, it is unknown whether sensory stimulation can alter the effects of fatiguing exercise on performance or spinal cord excitability. Thus, the aim of this experiment was to determine if sensory stimulation can interfere with fatigue-related suppression of spinal cord excitability, and alter fatigue rates during cycling sprints. Thirteen participants randomly performed three experimental sessions that included: unloaded cycling with sensory stimulation (CONTROL + STIM, sprints with sensory stimulation (SPRINT + STIM and sprints without stimulation (SPRINT. Seven participants also performed a fourth session (CONTROL, which consisted of unloaded cycling. During SPRINT and SPRINT + STIM, participants performed seven, 10 s cycling sprints interleaved with 3 min rest. For CONTROL and CONTROL + STIM, participants performed unloaded cycling for ~30 min. During SPRINT + STIM and CONTROL + STIM, participants received patterned sensory stimulation to nerves of the right foot. H-reflexes and M-waves of the right soleus were evoked by stimulation of the tibial nerve at multiple time points throughout exercise. Sensory stimulation facilitated soleus H-reflexes during unloaded cycling, whereas sprints suppressed soleus H-reflexes. While receiving sensory stimulation, there was less suppression of soleus H-reflexes and slowed reduction in average power output

Spinal Cord Excitability and Sprint Performance Are Enhanced by Sensory Stimulation During Cycling.

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Pearcey, Gregory E P; Noble, Steven A; Munro, Bridget; Zehr, E Paul

2017-01-01

Spinal cord excitability, as assessed by modulation of Hoffmann (H-) reflexes, is reduced with fatiguing isometric contractions. Furthermore, spinal cord excitability is reduced during non-fatiguing arm and leg cycling. Presynaptic inhibition of Ia terminals is believed to contribute to this suppression of spinal cord excitability. Electrical stimulation to cutaneous nerves reduces Ia presynaptic inhibition, which facilitates spinal cord excitability, and this facilitation is present during arm cycling. Although it has been suggested that reducing presynaptic inhibition may prolong fatiguing contractions, it is unknown whether sensory stimulation can alter the effects of fatiguing exercise on performance or spinal cord excitability. Thus, the aim of this experiment was to determine if sensory stimulation can interfere with fatigue-related suppression of spinal cord excitability, and alter fatigue rates during cycling sprints. Thirteen participants randomly performed three experimental sessions that included: unloaded cycling with sensory stimulation ( CONTROL + STIM ), sprints with sensory stimulation ( SPRINT + STIM ) and sprints without stimulation ( SPRINT ). Seven participants also performed a fourth session ( CONTROL ), which consisted of unloaded cycling. During SPRINT and SPRINT + STIM, participants performed seven, 10 s cycling sprints interleaved with 3 min rest. For CONTROL and CONTROL + STIM , participants performed unloaded cycling for ~30 min. During SPRINT + STIM and CONTROL + STIM , participants received patterned sensory stimulation to nerves of the right foot. H-reflexes and M-waves of the right soleus were evoked by stimulation of the tibial nerve at multiple time points throughout exercise. Sensory stimulation facilitated soleus H-reflexes during unloaded cycling, whereas sprints suppressed soleus H-reflexes. While receiving sensory stimulation, there was less suppression of soleus H-reflexes and slowed reduction in average power output, compared

Investigating the Relationship between Sprint and Jump Performances with Velocity and Power Parameters during Propulsive Phase of the Loaded-Squat Jump Exercise

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Can, Ibrahim

2018-01-01

The purpose of this study was to investigate the relationship between sprint and jump performance with velocity parameters in the loaded-squat jump exercise (SQ[subscript Loaded]). In accordance with this purpose, a total of 13 athletes competing in martial sports have participated in this study voluntarily. In this study, sprint tests, vertical…

Effects of caffeine and carbohydrate mouth rinses on repeated sprint performance.

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Beaven, C Martyn; Maulder, Peter; Pooley, Adrian; Kilduff, Liam; Cook, Christian

2013-06-01

Our purpose was to examine the effectiveness of carbohydrate and caffeine mouth rinses in enhancing repeated sprint ability. Previously, studies have shown that a carbohydrate mouth rinse (without ingestion) has beneficial effects on endurance performance that are related to changes in brain activity. Caffeine ingestion has also demonstrated positive effects on sprint performance. However, the effects of carbohydrate or caffeine mouth rinses on intermittent sprints have not been examined previously. Twelve males performed 5 × 6-s sprints interspersed with 24 s of active recovery on a cycle ergometer. Twenty-five milliliters of either a noncaloric placebo, a 6% glucose, or a 1.2% caffeine solution was rinsed in the mouth for 5 s prior to each sprint in a double-blinded and balanced cross-over design. Postexercise maximal heart rate and perceived exertion were recorded, along with power measures. A second experiment compared a combined caffeine-carbohydrate rinse with carbohydrate only. Compared with the placebo mouth rinse, carbohydrate substantially increased peak power in sprint 1 (22.1 ± 19.5 W; Cohen's effect size (ES), 0.81), and both caffeine (26.9 ± 26.9 W; ES, 0.71) and carbohydrate (39.1 ± 25.8 W; ES, 1.08) improved mean power in sprint 1. Experiment 2 demonstrated that a combination of caffeine and carbohydrate improved sprint 1 power production compared with carbohydrate alone (36.0 ± 37.3 W; ES, 0.81). We conclude that carbohydrate and (or) caffeine mouth rinses may rapidly enhance power production, which could have benefits for specific short sprint exercise performance. The ability of a mouth-rinse intervention to rapidly improve maximal exercise performance in the absence of fatigue suggests a central mechanism.

Effect of small sided handball game on aerobic capacity and repeated sprint ability of male handball players

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CHITTIBABU, Balasubramanian

2014-01-01

The purpose of this study was to determine the effects of four and eight weeks small-sided handball game on aerobic capacity and repeated sprint ability of male handball players. Sixteen (16) male university handball players volunteered to act as subjects and were randomly assigned to small-sided handball game group (SSHG) and control group (CG).  Small-sided handball game was administered three days in a week for eight weeks. Subjects were measured on aerobic capacity, total sprint time and ...

EFFECTS OF A SAND RUNNING SURFACE ON THE KINEMATICS OF SPRINTING AT MAXIMUM VELOCITY

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P E Alcaraz

2011-05-01

Full Text Available Performing sprints on a sand surface is a common training method for improving sprint-specific strength. For maximum specificity of training the athlete’s movement patterns during the training exercise should closely resemble those used when performing the sport. The aim of this study was to compare the kinematics of sprinting at maximum velocity on a dry sand surface to the kinematics of sprinting on an athletics track. Five men and five women participated in the study, and flying sprints over 30 m were recorded by video and digitized using biomechanical analysis software. We found that sprinting on a sand surface was substantially different to sprinting on an athletics track. When sprinting on sand the athletes tended to ‘sit’ during the ground contact phase of the stride. This action was characterized by a lower centre of mass, a greater forward lean in the trunk, and an incomplete extension of the hip joint at take-off. We conclude that sprinting on a dry sand surface may not be an appropriate method for training the maximum velocity phase in sprinting. Although this training method exerts a substantial overload on the athlete, as indicated by reductions in running velocity and stride length, it also induces detrimental changes to the athlete’s running technique which may transfer to competition sprinting.

Relationships between ground reaction impulse and sprint acceleration performance in team sport athletes.

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Kawamori, Naoki; Nosaka, Kazunori; Newton, Robert U

2013-03-01

Large horizontal acceleration in short sprints is a critical performance parameter for many team sport athletes. It is often stated that producing large horizontal impulse at each ground contact is essential for high short sprint performance, but the optimal pattern of horizontal and vertical impulses is not well understood, especially when the sprints are initiated from a standing start. This study was an investigation of the relationships between ground reaction impulses and sprint acceleration performance from a standing start in team sport athletes. Thirty physically active young men with team sport background performed 10-m sprint from a standing start, whereas sprint time and ground reaction forces were recorded during the first ground contact and at 8 m from the start. Associations between sprint time and ground reaction impulses (normalized to body mass) were determined by a Pearson's correlation coefficient (r) analysis. The 10-m sprint time was significantly (p < 0.01) correlated with net horizontal impulse (r = -0.52) and propulsive impulse (r = -0.66) measured at 8 m from the start. No significant correlations were found between sprint time and impulses recorded during the first ground contact after the start. These results suggest that applying ground reaction impulse in a more horizontal direction is important for sprint acceleration from a standing start. This is consistent with the hypothesis of training to increase net horizontal impulse production using sled towing or using elastic resistance devices, which needs to be validated by future longitudinal training studies.

Carbohydrate mouth rinse does not improve repeated sprint performance

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Leandro Ricardo Altimari

2013-09-01

Full Text Available The objective of this study was to evaluate the effect of a carbohydrate mouth rinse on the repeated sprint ability (RSA of young soccer players. Nine youth soccer players (15.0 ± 1.5 years; 60.7 ± 4.84 kg; 1.72 ± 0.05 m; 20.5 ± 1.25 kg/m2 were selected. The athletes were submitted to an RSA test consisting of six sprints of 40 m (going/return = 20 m + 20 m, separated by 20 s of passive recovery, under three experimental conditions: carbohydrate mouth rinse (CHO or placebo (PLA and control (CON. The mouth rinses containing CHO or PLA were administered 5 min and immediately before the beginning of the test in doses of 100 mL. The best sprint time (RSAbest, mean sprint time (RSAmean, and drop-off in sprint performance (fatigue index were determined for the different treatments. One-not identify significant differences (p> 0.05 in RSAbest (CHO way ANOVA for repeated measures did = 7.30 ± 0.31 s; PLA = 7.30 ± 0.30 s; CON = 7.26 ±0.16 s, RSA mean (CHO = 7.71 ± 0.30 s; PLA = 7.71 ± 0.25 s; CON = 7.66 ± 0.24s, or fatigue index (CHO = 5.58 ± 2.16%; PLA = 5.77 ± 3.04%; CON = 5.55 ±3.72%. The results suggest that a carbohydrate mouth rinse does not improve the repeated sprint performance of young soccer players.

Three Days of Intermittent Fasting: Repeated-Sprint Performance Decreased by Vertical-Stiffness Impairment.

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Cherif, Anissa; Meeusen, Romain; Farooq, Abdulaziz; Ryu, Joong; Fenneni, Mohamed Amine; Nikolovski, Zoran; Elshafie, Sittana; Chamari, Karim; Roelands, Bart

2017-03-01

To examine the effects of 3 d of intermittent fasting (3d-IF: abstaining from eating/drinking from dawn to sunset) on physical performance and metabolic responses to repeated sprints (RSs). Twenty-one active males performed an RS test (2 sets: 5 × 5-s maximal sprints with 25 s of recovery between and 3 min of recovery between sets on an instrumented treadmill) in 2 conditions: counterbalanced fed/control session (CS) and fasting session (FS). Biomechanical and biochemical markers were assessed preexercise and postexercise. Significant main effects of IF were observed for sprints: maximal speed (P = .016), mean speed (P = .015), maximal power (P = .035), mean power (P = .049), vertical stiffness (P = .032), and vertical center-of-mass displacement (P = .047). Sprint speed and vertical stiffness decreased during the 1st (P = .003 and P = .005) and 2nd sprints (P = .046 and P = .048) of set 2, respectively. Postexercise insulin decreased in CS (P = .023) but not in FS (P = .230). Free-fatty-acid levels were higher in FS than in CS at preexercise (P < .001) and at postexercise (P = .009). High-density lipoprotein cholesterol (HDL-C) was higher at postexercise in FS (1.32 ± 0.22 mmol/L) than in CS (1.26 ± 0.21 mmol/L, P = .039). The triglyceride (TG) concentration was decreased in FS (P < .05) compared with CS. 3d-IF impaired speed and power through a decrease in vertical stiffness during the initial runs of the 2nd set of RS. The findings of the current study confirmed the benefits of 3d-IF: improved HDL-C and TG profiles while maintaining total cholesterol and low-density lipoprotein cholesterol levels. Moreover, improving muscle power might be a key factor to retain a higher vertical stiffness and to partly counteract the negative effects of intermittent fasting.

Development of a neuromuscular electrical stimulation protocol for sprint training.

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Russ, David W; Clark, Brian C; Krause, Jodi; Hagerman, Fredrick C

2012-09-01

Sprint training is associated with several beneficial adaptations in skeletal muscle, including an enhancement of sarcoplasmic reticulum (SR) Ca(2+) release. Unfortunately, several patient populations (e.g., the elderly, those with cardiac dysfunction) that might derive great benefit from sprint exercise are unlikely to tolerate it. The purpose of this report was to describe the development of a tolerable neuromuscular electrical stimulation (NMES) protocol that induces skeletal muscle adaptations similar to those observed with sprint training. Our NMES protocol was modeled after a published sprint exercise protocol and used a novel electrode configuration and stimulation sequence to provide adequate training stimulus while maintaining subject tolerance. Nine young, healthy subjects (four men) began and completed the training protocol of the knee extensor muscles. All subjects completed the protocol, with ratings of discomfort far less than those reported in studies of traditional NMES. Training induced significant increases in SR Ca(2+) release and citrate synthase activity (~16% and 32%, respectively), but SR Ca(2+) uptake did not change. The percentage of myosin heavy chain IIx isoform was decreased significantly after training. At the whole muscle level, neither central activation nor maximum voluntary isometric contraction force were significantly altered, although isometric force did exhibit a trend toward an increase (~3%, P = 0.055). Surprisingly, the NMES training produced a significant increase in muscle cross-sectional area (~3%, P = 0.04). It seems that an appropriately designed NMES protocol can mimic many of the benefits of sprint exercise training, with a low overall time commitment and training volume. These findings suggest that NMES has the potential to bring the benefits of sprint exercise to individuals who are unable to tolerate traditional sprint training.

Effects of Strength Training on Postpubertal Adolescent Distance Runners.

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Blagrove, Richard C; Howe, Louis P; Cushion, Emily J; Spence, Adam; Howatson, Glyn; Pedlar, Charles R; Hayes, Philip R

2018-06-01

Strength training activities have consistently been shown to improve running economy (RE) and neuromuscular characteristics, such as force-producing ability and maximal speed, in adult distance runners. However, the effects on adolescent (training on several important physiological and neuromuscular qualities associated with distance running performance. Participants (n = 25, 13 female, 17.2 ± 1.2 yr) were paired according to their sex and RE and randomly assigned to a 10-wk strength training group (STG) or a control group who continued their regular training. The STG performed twice weekly sessions of plyometric, sprint, and resistance training in addition to their normal running. Outcome measures included body mass, maximal oxygen uptake (V˙O2max), speed at V˙O2max, RE (quantified as energy cost), speed at fixed blood lactate concentrations, 20-m sprint, and maximal voluntary contraction during an isometric quarter-squat. Eighteen participants (STG: n = 9, 16.1 ± 1.1 yr; control group: n = 9, 17.6 ± 1.2 yr) completed the study. The STG displayed small improvements (3.2%-3.7%; effect size (ES), 0.31-0.51) in RE that were inferred as "possibly beneficial" for an average of three submaximal speeds. Trivial or small changes were observed for body composition variables, V˙O2max and speed at V˙O2max; however, the training period provided likely benefits to speed at fixed blood lactate concentrations in both groups. Strength training elicited a very likely benefit and a possible benefit to sprint time (ES, 0.32) and maximal voluntary contraction (ES, 0.86), respectively. Ten weeks of strength training added to the program of a postpubertal distance runner was highly likely to improve maximal speed and enhances RE by a small extent, without deleterious effects on body composition or other aerobic parameters.

The effect of hamstring flexibility on peak hamstring muscle strain in sprinting

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Xianglin Wan

2017-09-01

Conclusion: A potential for hamstring injury exists during the late swing phase of sprinting. Peak hamstring muscle strains in sprinting are negatively correlated to hamstring flexibility across individuals. The magnitude of peak muscle strains is different among hamstring muscles in sprinting, which may explain the different injury rate among hamstring muscles.

The physical characteristics of match-play in English schoolboy and academy rugby union.

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Read, Dale B; Jones, Ben; Phibbs, Padraic J; Roe, Gregory A B; Darrall-Jones, Joshua; Weakley, Jonathon J S; Till, Kevin

2018-03-01

The aim was to compare the physical characteristics of under-18 academy and schoolboy rugby union competition by position (forwards and backs). Using a microsensor unit, match characteristics were recorded in 66 players. Locomotor characteristics were assessed by maximum sprint speed (MSS) and total, walking, jogging, striding and sprinting distances. The slow component (<2 m · s -1 ) of PlayerLoad TM (PL slow ), which is the accumulated accelerations from the three axes of movement, was analysed as a measure of low-speed activity (e.g., rucking). A linear mixed-model was assessed with magnitude-based inferences. Academy forwards and backs almost certainly and very likely covered greater total distance than school forwards and backs. Academy players from both positions were also very likely to cover greater jogging distances. Academy backs were very likely to accumulate greater PL slow and the academy forwards a likely greater sprinting distance than school players in their respective positions. The MSS, total, walking and sprinting distances were greater in backs (likely-almost certainly), while forwards accumulated greater PL slow (almost certainly) and jogging distance (very likely). The results suggest that academy-standard rugby better prepares players to progress to senior competition compared to schoolboy rugby.

Relación entre la fuerza máxima en squat y acciones de salto, sprint y golpeo de balón. (Relationship among maximal strength in squat exercise, jump, sprint and kicking ball performance.

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Alfredo Arija Blázquez

2008-01-01

Full Text Available ResumenEl objetivo del presente estudio fue analizar las posibles relaciones entre la fuerza máxima en squat y accionesexplosivas de salto, sprint y golpeo de balón. Para ello, se contó con una muestra formada por estudiantes de Ciencias del Deporte (N= 16; 19,6 ± 1,7 años de sexo masculino (con escasa experiencia en el entrenamiento de fuerza, que llevaron a cabo un test de 1RM en squat (calculándose el peso levantado, la fuerza media total y la fuerza dinámica máxima, tests de salto vertical (SJ, CMJ y CMJa, un test de sprint de 20 m (con mediciones de tiempo cada 5 m, y un test de golpeo con el pie donde se calculaba la velocidad del balón. Se encontraron coeficientes de correlación moderados (entre 0,52 y 0,67 y significativos de las medidas de fuerza máxima y las alturas de salto, mientras que los coeficientes obtenidos entre los tiempos de sprint y dichas medidas de fuerza máxima se situaron entre -0,06 y -0,32, no siendo ninguno de ellos significativo; al igual que tampoco fueron significativos los coeficientes de correlación de las medidas de fuerza máxima y la velocidad de tiro, se situaron entre 0,25 y 0,34. Por tanto, la relación entre la fuerza máxima en squat y la altura de salto en sujetos con escasa experiencia en el entrenamiento de fuerza resultó moderada, mientras que no parece existir relación con el tiempo de sprint y la velocidad de tiro.AbstractThe purpose of the present study was to analyze the possible relationships between maximal strength insquat exercise and jump, sprint and kicking ball actions. Sixteen males sport science students (19,6 ± 1,7years, with little experience in strength training, performed a 1RM in squat exercise (from which liftedweight, the total average- and maximal-dynamic strength was assessed, vertical jump (SJ, CMJ and CMJa, a 20 m sprint test (with time measurement every 5 m, and a kicking ball test where the velocity of the ball was calculated. Moderate (0,52 - 0,67 and

Anthropometric factors related to sprint and agility performance in young male soccer players

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Mathisen G

2015-11-01

Full Text Available Gunnar Mathisen, Svein Arne Pettersen School of Sport Sciences, UiT The Arctic University of Norway, Tromsø, Norway Objective: To investigate the relationship between anthropometrics and sprint and agility performance and describe the development of sprint (acceleration and agility performance in 10- to 16-year-old male soccer players. Methods: One hundred and thirty-two participants were divided into three age groups, 10–12 years (mean 10.8±0.50, 13–14 years (mean 13.9±0.50, and 15–16 years (mean 15.5±0.24, with assessment of 20 m sprint with 10 m split time and agility performance related to body height and body mass within groups. Results: In the 10- to 12-year-olds, there were no significant correlations between height, weight, and the performance variables, except for body mass, which was correlated to 10–20 m sprint (r=0.30. In the 13- to 14-year-olds, body height was significantly correlated with 10 m sprint (r=0.50 and 20 m sprint (r=0.52, as well as 10–20 m sprint (r=0.50 and agility performance (r=0.28. In the 15- to 16-year-old group, body height was correlated to 20 m (r=0.38 and 10–20 m (r=0.45 sprint. Body mass was significantly correlated to 10 m spring (r=0.35 in the 13- to 14-year-olds, as well as 20 m (r=0.33 and 10–20 m (r=0.35 sprint in the 15- to 16-year-olds. Conclusion: Height and body mass were significantly correlated with sprint performance in 13- to 16-year-old male soccer players. However, the 10- to 12-year-olds showed no significant relationship between sprint performance and anthropometrics, except for a small correlation in 10–20 m sprint. This may be attributed to maturation, with large differences in body height and body mass due to different patterns in the growth spurt. The agility performance related to anthropometrics was insignificant apart from a moderate correlation in the 13- to 14-year-olds. Keywords: youth soccer, running speed, development, football, puberty, skills 

Repeated-Sprint Sequences During Female Soccer Matches Using Fixed and Individual Speed Thresholds.

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Nakamura, Fábio Y; Pereira, Lucas A; Loturco, Irineu; Rosseti, Marcelo; Moura, Felipe A; Bradley, Paul S

2017-07-01

Nakamura, FY, Pereira, LA, Loturco, I, Rosseti, M, Moura, FA, and Bradley, PS. Repeated-sprint sequences during female soccer matches using fixed and individual speed thresholds. J Strength Cond Res 31(7): 1802-1810, 2017-The main objective of this study was to characterize the occurrence of single sprint and repeated-sprint sequences (RSS) during elite female soccer matches, using fixed (20 km·h) and individually based speed thresholds (>90% of the mean speed from a 20-m sprint test). Eleven elite female soccer players from the same team participated in the study. All players performed a 20-m linear sprint test, and were assessed in up to 10 official matches using Global Positioning System technology. Magnitude-based inferences were used to test for meaningful differences. Results revealed that irrespective of adopting fixed or individual speed thresholds, female players produced only a few RSS during matches (2.3 ± 2.4 sequences using the fixed threshold and 3.3 ± 3.0 sequences using the individually based threshold), with most sequences composing of just 2 sprints. Additionally, central defenders performed fewer sprints (10.2 ± 4.1) than other positions (fullbacks: 28.1 ± 5.5; midfielders: 21.9 ± 10.5; forwards: 31.9 ± 11.1; with the differences being likely to almost certainly associated with effect sizes ranging from 1.65 to 2.72), and sprinting ability declined in the second half. The data do not support the notion that RSS occurs frequently during soccer matches in female players, irrespective of using fixed or individual speed thresholds to define sprint occurrence. However, repeated-sprint ability development cannot be ruled out from soccer training programs because of its association with match-related performance.

Sprinting performance on the Woodway Curve 3.0 is related to muscle architecture.

Science.gov (United States)

Mangine, Gerald T; Fukuda, David H; Townsend, Jeremy R; Wells, Adam J; Gonzalez, Adam M; Jajtner, Adam R; Bohner, Jonathan D; LaMonica, Michael; Hoffman, Jay R; Fragala, Maren S; Stout, Jeffrey R

2015-01-01

To determine if unilateral measures of muscle architecture in the rectus femoris (RF) and vastus lateralis (VL) were related to (and predictive of) sprinting speed and unilateral (and bilateral) force (FRC) and power (POW) during a 30 s maximal sprint on the Woodway Curve 3.0 non-motorized treadmill. Twenty-eight healthy, physically active men (n = 14) and women (n = 14) (age = 22.9 ± 2.4 years; body mass = 77.1 ± 16.2 kg; height = 171.6 ± 11.2 cm; body-fa t = 19.4 ± 8.1%) completed one familiarization and one 30-s maximal sprint on the TM to obtain maximal sprinting speed, POW and FRC. Muscle thickness (MT), cross-sectional area (CSA) and echo intensity (ECHO) of the RF and VL in the dominant (DOM; determined by unilateral sprinting power) and non-dominant (ND) legs were measured via ultrasound. Pearson correlations indicated several significant (p architecture. Stepwise regression indicated that POW(DOM) was predictive of ipsilateral RF (MT and CSA) and VL (CSA and ECHO), while POW(ND) was predictive of ipsilateral RF (MT and CSA) and VL (CSA); sprinting power/force asymmetry was not predictive of architecture asymmetry. Sprinting time was best predicted by peak power and peak force, though muscle quality (ECHO) and the bilateral percent difference in VL (CSA) were strong architectural predictors. Muscle architecture is related to (and predictive of) TM sprinting performance, while unilateral POW is predictive of ipsilateral architecture. However, the extent to which architecture and other factors (i.e. neuromuscular control and sprinting technique) affect TM performance remains unknown.

Effects of three warm-up regimens of equal distance on VO2 kinetics during supramaximal exercise in Thoroughbred horses.

Science.gov (United States)

Mukai, K; Hiraga, A; Takahashi, T; Ohmura, H; Jones, J H

2010-11-01

Several studies have indicated that even low-intensity warm-up increases O(2) transport kinetics and that high-intensity warm-up may not be needed in horses. However, conventional warm-up exercise for Thoroughbred races is more intense than those utilised in previous studies of equine warm-up responses. To test the hypothesis that warm-up exercise at different intensities alters the kinetics and total contribution of aerobic power to total metabolic power in subsequent supramaximal (sprint) exercise in Thoroughbred horses. Nine well-trained Thoroughbreds ran until fatigue at 115% of maximal oxygen consumption (VO2max) 10 min after warming-up under each of 3 protocols of equal running distance: 400 s at 30% VO2max (LoWU), 200 s at 60% VO2max (MoWU) and 120 s at 100% VO2max (HiWU). Variables measured during exercise were rates of O(2) and CO(2) consumption/production (VO2,VO2), respiratory exchange ratio (RER), heart rate, blood lactate concentration and accumulation rate and blood gas variables. VO2 was significantly higher in HiWU than in LoWU at the onset of the sprint exercise and HR was significantly higher in HiWU than in LoWU throughout the sprint. Accumulation of blood lactate, RER, P(a)CO(2) and PvCO2 in the first 60 s were significantly lower in HiWU than in LoWU and MoWU. There were no significant differences in stroke volume, run time or arterial-mixed venous O(2) concentration. These results suggest HiWU accelerates kinetics and reduces reliance on net anaerobic power compared with LoWU at the onset of the subsequent sprint. © 2010 EVJ Ltd.

On the Total Variation Distance of Semi-Markov Chains

DEFF Research Database (Denmark)

Bacci, Giorgio; Bacci, Giovanni; Larsen, Kim Guldstrand

2015-01-01

Semi-Markov chains (SMCs) are continuous-time probabilistic transition systems where the residence time on states is governed by generic distributions on the positive real line. This paper shows the tight relation between the total variation distance on SMCs and their model checking problem over...

Activity profiles in U17, U20 and senior women's Brazilian National soccer teams during international competitions: Are there meaningful differences?

Science.gov (United States)

Ramos, Guilherme P; Nakamura, Fábio Y; Penna, Eduardo M; Wilke, Carolina Franco; Pereira, Lucas A; Loturco, Irineu; Capelli, Luciano; Mahseredjian, Fábio; Silami-Garcia, Emerson; Coimbra, Cândido C

2017-07-31

The aim of this study was to compare locomotor activity profiles of Brazilian top-class female soccer players competing at distinct age brackets (U17, U20, and Senior). External match load of 14 U17, 14 U20, and 17 Senior female soccer players competing in 6-7 full official international matches were assessed using global positioning systems (GPS). Total distance covered, distance covered in high intensity (HID:15.6-20 kmh), distance covered in sprints (sprint:>20 kmh), number of accelerations (Acc)>1 ms, decelerations (Dec) >-1 ms, and Player Load generally increased across the age brackets (U17Senior). For all playing positions, Senior athletes presented greater total distance, accelerations, and decelerations than U20 players. For high-intensity distance and sprints, only central defender and midfielder senior players presented greater values than U20 players. Senior players demonstrated higher values in all locomotor activities in comparison to U17 players, irrespective of playing positions. Except for central defenders that presented similar total distance, sprint distance, and number of accelerations between U20 and U17, the majority of match external loads evaluated in all playing positions were greater in U20 than in U17 players. These results provide useful information for player development and should be used to establish appropriate match-specific conditioning drills according to age categories.

Step-to-step spatiotemporal variables and ground reaction forces of intra-individual fastest sprinting in a single session.

Science.gov (United States)

Nagahara, Ryu; Mizutani, Mirai; Matsuo, Akifumi; Kanehisa, Hiroaki; Fukunaga, Tetsuo

2018-06-01

We aimed to investigate the step-to-step spatiotemporal variables and ground reaction forces during the acceleration phase for characterising intra-individual fastest sprinting within a single session. Step-to-step spatiotemporal variables and ground reaction forces produced by 15 male athletes were measured over a 50-m distance during repeated (three to five) 60-m sprints using a long force platform system. Differences in measured variables between the fastest and slowest trials were examined at each step until the 22nd step using a magnitude-based inferences approach. There were possibly-most likely higher running speed and step frequency (2nd to 22nd steps) and shorter support time (all steps) in the fastest trial than in the slowest trial. Moreover, for the fastest trial there were likely-very likely greater mean propulsive force during the initial four steps and possibly-very likely larger mean net anterior-posterior force until the 17th step. The current results demonstrate that better sprinting performance within a single session is probably achieved by 1) a high step frequency (except the initial step) with short support time at all steps, 2) exerting a greater mean propulsive force during initial acceleration, and 3) producing a greater mean net anterior-posterior force during initial and middle acceleration.

Muscle Damage and Metabolic Responses to Repeated-Sprint Running With and Without Deceleration.

Science.gov (United States)

Minahan, Clare L; Poke, Daniel P; Morrison, Jaime; Bellinger, Phillip M

2018-04-04

Minahan, CL, Poke, DP, Morrison, J, and Bellinger, PM. Muscle damage and metabolic responses to repeated-sprint running with and without deceleration. J Strength Cond Res XX(X): 000-000, 2017-This study aimed to determine whether repeated-sprint running with deceleration aggravates markers of muscle damage or delays the recovery of performance compared with repeated-sprint running without deceleration. Fourteen male team-sport athletes performed 2 randomly ordered testing sessions on a nonmotorized treadmill with one session requiring participants to decelerate (TMd) within 4 seconds before stopping or immediately step to the side of the treadmill belt at the completion of each sprint (TMa). Peak and mean velocities, speed decrement, blood lactate concentrations, and oxygen uptake were monitored during the repeated-sprint running protocols. Countermovement vertical jump (CMJ) performance, perceived muscle soreness, sit-and-reach flexibility, plasma creatine kinase (CK), lactate dehydrogenase (LDH), and myoglobin (Mb) concentrations were quantified immediately before and after and 45 minutes, 24 and 48 hours after repeated-sprint running protocols. Although muscle damage was indicated by increases in CK, LDH, and Mb (p ≤ 0.05) in both groups, there was no significant effect of condition (TMa vs. TMd) on any of the measured performance or physiological variables (p > 0.05). The present study indicated that the removal of deceleration from repeated-sprint running on a nonmotorized treadmill has no effect on metabolism or performance during or after repeated-sprint running or markers of muscle damage.

Positional Match Running Performance in Elite Gaelic Football.

Science.gov (United States)

Malone, Shane; Solan, Barry; Collins, Kieran D; Doran, Dominic A

2016-08-01

Malone, S, Solan, B, Collins, KD, and Doran, DA. Positional match running performance in elite Gaelic football. J Strength Cond Res 30(8): 2292-2298, 2016-There is currently limited information available on match running performance in Gaelic football. The objective of the current study was to report on the match running profile of elite male Gaelic football and assess positional running performance. In this observational study, 50 elite male Gaelic football players wore 4-Hz global positioning systems units (VX Sports) across 30 competitive games with a total of 215 full game data sets collected. Activity was classed according to total distance, high-speed distance (≥17 km·h), sprint distance (≥22 km·h), mean velocity (km·h), peak velocity (km·h), and number of accelerations. The average match distance was 8,160 ± 1,482 m, reflective of a relative distance of 116 ± 21 m·min, with 1,731 ± 659 m covered at high speed, which is reflective of a relative high-speed distance of 25 ± 9 m·min. The observed sprint distance was 445 ± 169 m distributed across 44 sprint actions. The peak velocity was 30.3 ± 1.8 km·h with a mean velocity of 6.5 ± 1.2 km·h. Players completed 184 ± 40 accelerations, which represent 2.6 ± 0.5 accelerations per minute. There were significant differences between positional groups for both total running distance, high-speed running distance, and sprint distance, with midfielders covering more total and high-speed running distance, compared with other positions (p football match play.

Repeated sprint ability in young basketball players: one vs. two changes of direction (Part 2).

Science.gov (United States)

Attene, Giuseppe; Laffaye, Guillaume; Chaouachi, Anis; Pizzolato, Fabio; Migliaccio, Gian Mario; Padulo, Johnny

2015-01-01

The aim of this study was to compare the training effects based on repeated sprint ability (RSA) (with one change of direction) with an intensive repeated sprint ability (IRSA) (with two changes of direction) on jump performance and aerobic fitness. Eighteen male basketball players were assigned to repeated sprint ability and intensive repeated sprint ability training groups (RSAG and IRSAG). RSA, IRSA, squat jump (SJ), countermovement jump (CMJ) and Yo-Yo intermittent recovery level 1 test were assessed before and after four training weeks. The RSA and IRSA trainings consisted of three sets of six sprints (first two weeks) and eight sprints (second two weeks) with 4-min sets recovery and 20-s of sprints recovery. Four weeks of training led to an overall improvement in most of the measures of RSA, but little evidence of any differences between the two training modes. Jump performance was enhanced: CMJ of 7.5% (P training with one/two changes of direction promotes improvements in both RSA and IRSA respectively but the better increase on jump performance shown a few changes on sprint and endurance performances.

Development of Repeated Sprint Ability in Talented Youth Basketball Players

NARCIS (Netherlands)

te Wierike, Sanne C. M.; de Jong, Mark C.; Tromp, Eveline J. Y.; Vuijk, Pieter J.; Lemmink, Koen A. P. M.; Malina, Robert M.; Elferink-Gemser, Marije T.; Visscher, Chris

te Wierike, SCM, de Jong, MC, Tromp, EJY, Vuijk, PJ, Lemmink, KAPM, Malina, RM, Elferink-Gemser, MT, and Visscher, C. Development of repeated sprint ability in talented youth basketball players. J Strength Cond Res 28(4): 928-934, 2014-Factors affecting repeated sprint ability (RSA) were evaluated

Effects of Resisted Sprint Training and Traditional Power Training on Sprint, Jump, and Balance Performance in Healthy Young Adults: A Randomized Controlled Trial.

Science.gov (United States)

Prieske, Olaf; Krüger, Tom; Aehle, Markus; Bauer, Erik; Granacher, Urs

2018-01-01

Power training programs have proved to be effective in improving components of physical fitness such as speed. According to the concept of training specificity, it was postulated that exercises must attempt to closely mimic the demands of the respective activity. When transferring this idea to speed development, the purpose of the present study was to examine the effects of resisted sprint (RST) vs. traditional power training (TPT) on physical fitness in healthy young adults. Thirty-five healthy, physically active adults were randomly assigned to a RST ( n = 10, 23 ± 3 years), a TPT ( n = 9, 23 ± 3 years), or a passive control group ( n = 16, 23 ± 2 years). RST and TPT exercised for 6 weeks with three training sessions/week each lasting 45-60 min. RST comprised frontal and lateral sprint exercises using an expander system with increasing levels of resistance that was attached to a treadmill (h/p/cosmos). TPT included ballistic strength training at 40% of the one-repetition-maximum for the lower limbs (e.g., leg press, knee extensions). Before and after training, sprint (20-m sprint), change-of-direction speed (T-agility test), jump (drop, countermovement jump), and balance performances (Y balance test) were assessed. ANCOVA statistics revealed large main effects of group for 20-m sprint velocity and ground contact time (0.81 ≤ d ≤ 1.00). Post-hoc tests showed higher sprint velocity following RST and TPT (0.69 ≤ d ≤ 0.82) when compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to 4.5% for RST [90%CI: (-1.1%;10.1%), d = 1.23] and 2.6% for TPT [90%CI: (0.4%;4.8%), d = 1.59]. Additionally, ground contact times during sprinting were shorter following RST and TPT (0.68 ≤ d ≤ 1.09) compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to -6.3% for RST [90%CI: (-11.4%;-1.1%), d = 1.45) and -2.7% for TPT [90%CI: (-4.2%;-1.2%), d = 2.36]. Finally, effects for change

Neuromuscular adjustments of the quadriceps muscle after repeated cycling sprints.

Directory of Open Access Journals (Sweden)

Olivier Girard

Full Text Available PURPOSE: This study investigated the supraspinal processes of fatigue of the quadriceps muscle in response to repeated cycling sprints. METHODS: Twelve active individuals performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s, followed 6 min later by 5 × 6-s sprints (recovery = 30 s. Transcranial magnetic and electrical femoral nerve stimulations during brief (5-s and sustained (30-s isometric contractions of the knee extensors were performed before and 3 min post-exercise. RESULTS: Maximal strength of the knee extensors decreased during brief and sustained contractions (~11% and 9%, respectively; P0.05. While cortical voluntary activation declined (P 40% reduced (P<0.001 following exercise. CONCLUSION: The capacity of the motor cortex to optimally drive the knee extensors following a repeated-sprint test was shown in sustained, but not brief, maximal isometric contractions. Additionally, peripheral factors were largely involved in the exercise-induced impairment in neuromuscular function, while corticospinal excitability was well-preserved.

Acute and Post-Exercise Physiological Responses to High-Intensity Interval Training in Endurance and Sprint Athletes

Science.gov (United States)

Cipryan, Lukas; Tschakert, Gerhard; Hofmann, Peter

2017-01-01

The purpose of the presented study was to compare acute and post-exercise differences in cardiorespiratory, metabolic, cardiac autonomic, inflammatory and muscle damage responses to high-intensity interval exercise (HIIT) between endurance and sprint athletes. The study group consisted of sixteen highly-trained males (age 22.1 ± 2.5 years) participating in endurance (n = 8) or sprint (n = 8) sporting events. All the participants underwent three exercise sessions: short HIIT (work interval duration 30s), long HIIT (3min) and constant load exercise (CE). The exercise interventions were matched for mean power, total time and in case of HIIT interventions also for work-to-relief ratio. The acute cardiorespiratory (HR, V̇O2, RER) and metabolic (lactate) variables as well as the post-exercise changes (up to 3 h) in the heart rate variability, inflammation (interleukin-6, leucocytes) and muscle damage (creatine kinase, myoglobin) were monitored. Endurance athletes performed exercise interventions with moderately (CE) or largely (both HIIT modes) higher mean V̇O2. These differences were trivial/small when V̇O2 was expressed as a percentage of V̇O2max. Moderately to largely lower RER and lactate values were found in endurance athletes. Markers of cardiac autonomic regulation, inflammation and muscle damage did not reveal any considerable differences between endurance and sprint athletes. In conclusions, endurance athletes were able to perform both HIIT formats with increased reliance on aerobic metabolic pathways although exercise intensity was identical in relative terms for all the participants. However, other markers of the acute and early post-exercise physiological response to these HIIT interventions indicated similarities between endurance and sprint athletes. Key points The manner in which each training background (endurance vs. sprint) influences the response to HIIT is not well known. Despite the identical exercise intensity in relative terms, endurance

The reliability and validity of fatigue measures during multiple-sprint work: an issue revisited.

Science.gov (United States)

Glaister, Mark; Howatson, Glyn; Pattison, John R; McInnes, Gill

2008-09-01

The ability to repeatedly produce a high-power output or sprint speed is a key fitness component of most field and court sports. The aim of this study was to evaluate the validity and reliability of eight different approaches to quantify this parameter in tests of multiple-sprint performance. Ten physically active men completed two trials of each of two multiple-sprint running protocols with contrasting recovery periods. Protocol 1 consisted of 12 x 30-m sprints repeated every 35 seconds; protocol 2 consisted of 12 x 30-m sprints repeated every 65 seconds. All testing was performed in an indoor sports facility, and sprint times were recorded using twin-beam photocells. All but one of the formulae showed good construct validity, as evidenced by similar within-protocol fatigue scores. However, the assumptions on which many of the formulae were based, combined with poor or inconsistent test-retest reliability (coefficient of variation range: 0.8-145.7%; intraclass correlation coefficient range: 0.09-0.75), suggested many problems regarding logical validity. In line with previous research, the results support the percentage decrement calculation as the most valid and reliable method of quantifying fatigue in tests of multiple-sprint performance.

The Reliability and Validity of Fatigue Measures During Multiple-Sprint Work: An Issue Revisited

OpenAIRE

Glaister, Mark; Howatson, Glyn; Pattison, John R.; McInnes, Gill

2008-01-01

The ability to repeatedly produce a high-power output or sprint speed is a key fitness component of most field and court sports. The aim of this study was to evaluate the validity and reliability of eight different approaches to quantify this parameter in tests of multiple-sprint performance. Ten physically active men completed two trials of each of two multiple-sprint running protocols with contrasting recovery periods. Protocol 1 consisted of 12 × 30-m sprints repeated every 35 seconds; pro...

Comparison of Cardiorespiratory and Metabolic Responses in Kettlebell High-Intensity Interval Training Versus Sprint Interval Cycling.

Science.gov (United States)

Williams, Brian M; Kraemer, Robert R

2015-12-01

The purpose of this study was to determine the effectiveness of a novel exercise protocol we developed for kettlebell high-intensity interval training (KB-HIIT) by comparing the cardiorespiratory and metabolic responses to a standard sprint interval cycling (SIC) exercise protocol. Eight men volunteered for the study and completed 2 preliminary sessions, followed by two 12-minute sessions of KB-HIIT and SIC in a counterbalanced fashion. In the KB-HITT session, 3 circuits of 4 exercises were performed using a Tabata regimen. In the SIC session, three 30-second sprints were performed, with 4 minutes of recovery in between the first 2 sprints and 2.5 minutes of recovery after the last sprint. A within-subjects' design over multiple time points was used to compare oxygen consumption (V[Combining Dot Above]O2), respiratory exchange ratio (RER), tidal volume (TV), breathing frequency (f), minute ventilation (VE), caloric expenditure rate (kcal·min), and heart rate (HR) between the exercise protocols. Additionally, total caloric expenditure was compared. A significant group effect, time effect, and group × time interaction were found for V[Combining Dot Above]O2, RER, and TV, with V[Combining Dot Above]O2 being higher and TV and RER being lower in the KB-HIIT compared with the SIC. Only a significant time effect and group × time interaction were found for f, VE, kcal·min, and HR. Additionally, total caloric expenditure was found to be significantly higher during the KB-HIIT. The results of this study suggest that KB-HIIT may be more attractive and sustainable than SIC and can be effective in stimulating cardiorespiratory and metabolic responses that could improve health and aerobic performance.

Comparison of Sprint Fidelis and Riata defibrillator lead failure rates.

Science.gov (United States)

Fazal, Iftikhar A; Shepherd, Ewen J; Tynan, Margaret; Plummer, Christopher J; McComb, Janet M

2013-09-30

Sprint Fidelis and Riata defibrillator leads are prone to early failure. Few data exist on the comparative failure rates and mortality related to lead failure. The aims of this study were to determine the failure rate of Sprint Fidelis and Riata leads, and to compare failure rates and mortality rates in both groups. Patients implanted with Sprint Fidelis leads and Riata leads at a single centre were identified and in July 2012, records were reviewed to ascertain lead failures, deaths, and relationship to device/lead problems. 113 patients had Sprint Fidelis leads implanted between June 2005 and September 2007; Riata leads were implanted in 106 patients between January 2003 and February 2008. During 53.0 ± 22.3 months of follow-up there were 13 Sprint Fidelis lead failures (11.5%, 2.60% per year) and 25 deaths. Mean time to failure was 45.1 ± 15.5 months. In the Riata lead cohort there were 32 deaths, and 13 lead failures (11.3%, 2.71% per year) over 54.8 ± 26.3 months follow-up with a mean time to failure of 53.5 ± 24.5 months. There were no significant differences in the lead failure-free Kaplan-Meier survival curve (p=0.77), deaths overall (p=0.17), or deaths categorised as sudden/cause unknown (p=0.54). Sprint Fidelis and Riata leads have a significant but comparable failure rate at 2.60% per year and 2.71% per year of follow-up respectively. The number of deaths in both groups is similar and no deaths have been identified as being related to lead failure in either cohort. Copyright © 2012. Published by Elsevier Ireland Ltd.

The Association of Sprint Performance with Anthropometric Parameters in Youth Soccer Players

Directory of Open Access Journals (Sweden)

Arjan Hyka

2017-02-01

Full Text Available Several studies have investigated the association between strength and speed, showing that stronger athletes perform better during sprint performances (Baker & Nance, 1999. Moreover, the aim of this study was to evaluate the correlation between sprint performance and anthropometric parameters. Subjects were 32 youth soccer players. The age of participants was 15.1±0.3 years. Speed time (50 m sprint was evaluated during sprint test, and anthropometric parameters were measured (weight, height, percent body fat. Correlation analysis (Pearson test was performed to evaluate the correlation between speed and anthropometrics. Results showed correlation between body weight and speed (r=-0.041 Sig=0.834; BMI values and speed (r=0.231; Sig=0.236, body height and speed (r=-0.384; Sig=0.044; percent body fat and speed (r=0.440; Sig=0.019.In conclusion, the results of this study show no significance association between body weight and BMI with sprint performance and significance correlation between body height (negative correlation and percent body fat (positive correlation with speed.

Intermittent-sprint performance and muscle glycogen after 30 h of sleep deprivation.

Science.gov (United States)

Skein, Melissa; Duffield, Rob; Edge, Johann; Short, Michael J; Mündel, Toby

2011-07-01

The aim of this study was to determine the effects of 30 h of sleep deprivation on consecutive-day intermittent-sprint performance and muscle glycogen content. Ten male, team-sport athletes performed a single-day "baseline" session and two consecutive-day experimental trials separated either by a normal night's sleep (CONT1 and CONT2) or no sleep (SDEP1 and SDEP2). Each session included a 30-min graded exercise run and 50-min intermittent-sprint exercise protocol, including a 15-m maximal sprint every minute and self-paced exercise bouts of varying intensities. Muscle biopsies were extracted before and after exercise during the baseline session and before exercise on day 2 during experimental trials. Voluntary force and activation of the right quadriceps, nude mass, HR, core temperature, capillary blood lactate and glucose, RPE, and a modified POMS were recorded before, after, and during the exercise protocols. Mean sprint times were slower on SDEP2 (2.78±0.17 s) compared with SDEP1 (2.70±0.16 s) and CONT2 (2.74±0.15 s, PSleep loss did not affect RPE but negatively affected POMS ratings (PSleep loss and associated reductions in muscle glycogen and perceptual stress reduced sprint performance and slowed pacing strategies during intermittent-sprint exercise for male team-sport athletes.

The relationship between ventilatory threshold and repeated-sprint ability in competitive male ice hockey players

Directory of Open Access Journals (Sweden)

Matthew R. Lowery

2018-04-01

Full Text Available Background/objective: The relationship between ventilatory threshold (VT1, VT2 and repeated-sprint ability (RSA in competitive male ice hockey players was investigated. Methods: Forty-three male ice hockey players aged 18–23 years competing in NCAA Division I, NCAA Division III, and Junior A level participated. Participants performed an incremental graded exercise test on a skate treadmill to determine V˙O2peak, VT1, and VT2 using MedGraphics Breezesuit™ software (v-slope. Participants performed an on-ice repeated shift (RSA test consisting of 8-maximal skating bouts, lasting approximately 25 s and interspersed with 90 s of passive recovery, to determine first gate, second gate, and total sprint decrement (%dec. Pearson product-moment correlations and multiple regressions were used to assess relationships between ventilatory threshold variables (VT1, VT2, Stage at VT1, and Stage at VT2 and RSA (first gate, second gate, and total course decrement. Results: Stage at VT2 was the only variable substantially correlated with first gate (r = −0.35; P < 0.05, second gate (r = −0.58; P < 0.001 and total course decrement (r = −0.42; P < 0.05. Conclusion: The results of this study demonstrated that VT is substantially associated with RSA, and VT2 is more strongly correlated with RSA than V˙O2peak. This study suggests that longer duration high-intensity interval training at intensities that increase workrate at VT2 may lead to possible improvements in RSA. Keywords: Athletes, Aerobic capacity, Fatigue, Sprint decrement

Effects of Repeated-Sprint Training in Hypoxia on Sea-Level Performance: A Meta-Analysis.

Science.gov (United States)

Brocherie, Franck; Girard, Olivier; Faiss, Raphaël; Millet, Grégoire P

2017-08-01

Repeated-sprint training in hypoxia (RSH) is a recent intervention regarding which numerous studies have reported effects on sea-level physical performance outcomes that are debated. No previous study has performed a meta-analysis of the effects of RSH. We systematically reviewed the literature and meta-analyzed the effects of RSH versus repeated-sprint training in normoxia (RSN) on key components of sea-level physical performance, i.e., best and mean (all sprint) performance during repeated-sprint exercise and aerobic capacity (i.e., maximal oxygen uptake [[Formula: see text

Comparison of step-by-step kinematics in repeated 30m sprints in female soccer players.

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van den Tillaar, Roland

2018-01-04

The aim of this study was to compare kinematics in repeated 30m sprints in female soccer players. Seventeen subjects performed seven 30m sprints every 30s in one session. Kinematics were measured with an infrared contact mat and laser gun, and running times with an electronic timing device. The main findings were that sprint times increased in the repeated sprint ability test. The main changes in kinematics during the repeated sprint ability test were increased contact time and decreased step frequency, while no change in step length was observed. The step velocity increased in almost each step until the 14, which occurred around 22m. After this, the velocity was stable until the last step, when it decreased. This increase in step velocity was mainly caused by the increased step length and decreased contact times. It was concluded that the fatigue induced in repeated 30m sprints in female soccer players resulted in decreased step frequency and increased contact time. Employing this approach in combination with a laser gun and infrared mat for 30m makes it very easy to analyse running kinematics in repeated sprints in training. This extra information gives the athlete, coach and sports scientist the opportunity to give more detailed feedback and help to target these changes in kinematics better to enhance repeated sprint performance.

Increases in lower-body strength transfer positively to sprint performance: a systematic review with meta-analysis.

Science.gov (United States)

Seitz, Laurent B; Reyes, Alvaro; Tran, Tai T; Saez de Villarreal, Eduardo; Haff, G Gregory

2014-12-01

Although lower-body strength is correlated with sprint performance, whether increases in lower-body strength transfer positively to sprint performance remain unclear. This meta-analysis determined whether increases in lower-body strength (measured with the free-weight back squat exercise) transfer positively to sprint performance, and identified the effects of various subject characteristics and resistance-training variables on the magnitude of sprint improvement. A computerized search was conducted in ADONIS, ERIC, SPORTDiscus, EBSCOhost, Google Scholar, MEDLINE and PubMed databases, and references of original studies and reviews were searched for further relevant studies. The analysis comprised 510 subjects and 85 effect sizes (ESs), nested with 26 experimental and 11 control groups and 15 studies. There is a transfer between increases in lower-body strength and sprint performance as indicated by a very large significant correlation (r = -0.77; p = 0.0001) between squat strength ES and sprint ES. Additionally, the magnitude of sprint improvement is affected by the level of practice (p = 0.03) and body mass (r = 0.35; p = 0.011) of the subject, the frequency of resistance-training sessions per week (r = 0.50; p = 0.001) and the rest interval between sets of resistance-training exercises (r = -0.47; p ≤ 0.001). Conversely, the magnitude of sprint improvement is not affected by the athlete's age (p = 0.86) and height (p = 0.08), the resistance-training methods used through the training intervention, (p = 0.06), average load intensity [% of 1 repetition maximum (RM)] used during the resistance-training sessions (p = 0.34), training program duration (p = 0.16), number of exercises per session (p = 0.16), number of sets per exercise (p = 0.06) and number of repetitions per set (p = 0.48). Increases in lower-body strength transfer positively to sprint performance. The magnitude of sprint improvement is affected by numerous subject characteristics and resistance

On the Importance of "Front-Side Mechanics" in Athletics Sprinting.

Science.gov (United States)

Haugen, Thomas; Danielsen, Jørgen; Alnes, Leif Olav; McGhie, David; Sandbakk, Øyvind; Ettema, Gertjan

2018-05-16

Practitioners have, for many years, argued that athletic sprinters should optimize front-side mechanics (leg motions occurring in front of the extended line through the torso) and minimize back-side mechanics. This study aimed to investigate if variables related to front- and back-side mechanics can be distinguished from other previously highlighted kinematic variables (spatiotemporal variables and variables related to segment configuration and velocities at touchdown) in how they statistically predict performance. A total of 24 competitive sprinters (age: 23.1 [3.4] y, height: 1.81 [0.06] m, body mass: 75.7 [5.6] kg, and 100-m personal best: 10.86 [0.22] s) performed two 20-m starts from block and 2 to 3 flying sprints over 20 m. Kinematics were recorded in 3D using a motion tracking system with 21 cameras at a 250 Hz sampling rate. Several front- and back-side variables, including thigh (r = .64) and knee angle (r = .51) at lift-off and maximal thigh extension (r = .66), were largely correlated (P mechanics were crucial for sprint performance among the investigated sprinters.

The effects of precompetition massage on the kinematic parameters of 20-m sprint performance.

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Fletcher, Iain M

2010-05-01

The purpose of this study was to investigate what effect precompetition massage has on short-term sprint performance. Twenty male collegiate games players, with a minimum training/playing background of 3 sessions per week, were assigned to a randomized, counter-balanced, repeated-measures designed experiment used to analyze 20-m sprints performance. Three discrete warm-up modalities, consisting of precompetition massage, a traditional warm-up, and a precompetition massage combined with a traditional warm-up were used. Massage consisted of fast, superficial techniques designed to stimulate the main muscle groups associated with sprint running. Twenty-meter sprint performance and core temperature were assessed post warm-up interventions. Kinematic differences between sprints were assessed through a 2-dimensional computerized motion analysis system (alpha level p velocity were found to be significantly greater in the warm-up and massage combined with warm-up modalities when compared to massage alone. No significant differences were demonstrated in any measures when the warm-up and massage and warm-up combined conditions were compared. Massage as a preperformance preparation strategy seems to decrease 20-m sprint performance when compared to a traditional warm-up, although its combination with a normal active warm-up seems to have no greater benefit then active warm-up alone. Therefore, massage use prior to competition is questionable because it appears to have no effective role in improving sprint performance.

Reliability characteristics and applicability of a repeated sprint ability test in male young soccer players

DEFF Research Database (Denmark)

Castagna, Carlo; Francini, Lorenzo; Krustrup, Peter

2018-01-01

The aim of this study was to examine the usefulness and reliability characteristics of a repeated sprint ability test considering 5 line sprints of 30-m interspersed with 30-s of active recovery in non-elite outfield young male soccer players. Twenty-six (age 14.9±1.2 years, height 1.72±0.12 cm......, body mass 62.2±5.1 kg) players were tested 48 hours and 7 days apart for 5x30-m performance over 5 trials (T1-T5). Short- (T1-T2) and long-term reliability (T1-T3-T4-T5) were assessed with Intraclass Correlation Coefficient (ICC) and with typical error for measurement (TEM). Short- and long...... study revealed that the 5x30-m sprint test is a reliable field test in the short and long-term when the sum of sprint times and the best sprint performance are considered as outcome variables. Sprint performance decrements variables showed large variability across trials....

The influence of parachute-resisted sprinting on running mechanics in collegiate track athletes.

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Paulson, Sally; Braun, William A

2011-06-01

The influence of parachute-resisted sprinting on running mechanics in collegiate track athletes. The aim of this investigation was to compare the acute effects of parachute-resisted (PR) sprinting on selected kinematic variables. Twelve collegiate sprinters (mean age 19.58 ± 1.44 years, mass 69.32 ± 14.38 kg, height 1.71 ± 9.86 m) ran a 40-yd dash under 2 conditions: PR sprint and sprint without a parachute (NC) that were recorded on a video computer system (60 Hz). Sagittal plane kinematics of the right side of the body was digitized to calculate joint angles at initial ground contact (IGC) and end ground contact (EGC), ground contact (GC) time, stride rate (SR), stride length (SL), and the times of the 40-yd dashes. The NC 40-yd dash time was significantly faster than the PR trial (p 0.05). This study suggests that PR sprinting does not acutely affect GC time, SR, SL and upper extremity or lower extremity joint angles during weight acceptance (IGC) in collegiate sprinters. However, PR sprinting increased shoulder flexion by 23.5% at push-off and decreased speed by 4.4%. While sprinting with the parachute, the athlete's movement patterns resembled their mechanics during the unloaded condition. This indicates the external load caused by PR did not substantially overload the runner, and only caused a minor change in the shoulder during push-off. This sports-specific training apparatus may provide coaches with another method for training athletes in a sports-specific manner without causing acute changes to running mechanics.

Changes in Muscle and Cerebral Deoxygenation and Perfusion during Repeated Sprints in Hypoxia to Exhaustion

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Sarah J. Willis

2017-10-01

Full Text Available During supramaximal exercise, exacerbated at exhaustion and in hypoxia, the circulatory system is challenged to facilitate oxygen delivery to working tissues through cerebral autoregulation which influences fatigue development and muscle performance. The aim of the study was to evaluate the effects of different levels of normobaric hypoxia on the changes in peripheral and cerebral oxygenation and performance during repeated sprints to exhaustion. Eleven recreationally active participants (six men and five women; 26.7 ± 4.2 years, 68.0 ± 14.0 kg, 172 ± 12 cm, 14.1 ± 4.7% body fat completed three randomized testing visits in conditions of simulated altitude near sea-level (~380 m, FIO2 20.9%, ~2000 m (FIO2 16.5 ± 0.4%, and ~3800 m (FIO2 13.3 ± 0.4%. Each session began with a 12-min warm-up followed by two 10-s sprints and the repeated cycling sprint (10-s sprint: 20-s recovery test to exhaustion. Measurements included power output, vastus lateralis, and prefrontal deoxygenation [near-infrared spectroscopy, delta (Δ corresponds to the difference between maximal and minimal values], oxygen uptake, femoral artery blood flow (Doppler ultrasound, hemodynamic variables (transthoracic impedance, blood lactate concentration, and rating of perceived exertion. Performance (total work, kJ; −27.1 ± 25.8% at 2000 m, p < 0.01 and −49.4 ± 19.3% at 3800 m, p < 0.001 and pulse oxygen saturation (−7.5 ± 6.0%, p < 0.05 and −18.4 ± 5.3%, p < 0.001, respectively decreased with hypoxia, when compared to 400 m. Muscle Δ hemoglobin difference ([Hbdiff] and Δ tissue saturation index (TSI were lower (p < 0.01 at 3800 m than at 2000 and 400 m, and lower Δ deoxyhemoglobin resulted at 3800 m compared with 2000 m. There were reduced changes in peripheral [Δ[Hbdiff], ΔTSI, Δ total hemoglobin ([tHb

EL ENTRENAMIENTO DEL SPRINT CON MÉTODOS RESISTIDOS

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Pedro E. Alcaraz Ramón

2010-01-01

Full Text Available Para la mejora del rendimiento en el sprint se utilizan distintos métodos de entrenamiento, entre los más populares se encuentran los métodos resistidos. Un método resistido, para el sprint, se caracteriza por utilizar sprints con una sobrecarga o resistencia añadida. Dependiendo de las características del dispositivo, tanto la magnitud como la dirección de la resistencia va a ser diferente. Así, existen distintos tipos de métodos resistidos, estos son: arrastres de trineos o ruedas, lastres de chalecos o cinturones, arrastres de paracaídas, carreras cuesta arriba, e incluso carreras sobre la arena de la playa. El principal objetivo al usar métodos resistidos es mejorar la fuerza específica de los deportistas sin producir una modificación significativa de la técnica del deportista. En el presente trabajo se revisan las características y efectos de los métodos resistidos tanto de forma aguda, como sus efectos a corto, medio y largo plazo.

Space Radiation Intelligence System (SPRINTS), Phase I

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National Aeronautics and Space Administration — NextGen Federal Systems proposes an innovative SPace Radiation INTelligence System (SPRINTS) which provides an interactive and web-delivered capability that...

Comparison of step-by-step kinematics of resisted, assisted and unloaded 20-m sprint runs.

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van den Tillaar, Roland; Gamble, Paul

2018-03-26

This investigation examined step-by-step kinematics of sprint running acceleration. Using a randomised counterbalanced approach, 37 female team handball players (age 17.8 ± 1.6 years, body mass 69.6 ± 9.1 kg, height 1.74 ± 0.06 m) performed resisted, assisted and unloaded 20-m sprints within a single session. 20-m sprint times and step velocity, as well as step length, step frequency, contact and flight times of each step were evaluated for each condition with a laser gun and an infrared mat. Almost all measured parameters were altered for each step under the resisted and assisted sprint conditions (η 2  ≥ 0.28). The exception was step frequency, which did not differ between assisted and normal sprints. Contact time, flight time and step frequency at almost each step were different between 'fast' vs. 'slow' sub-groups (η 2  ≥ 0.22). Nevertheless overall both groups responded similarly to the respective sprint conditions. No significant differences in step length were observed between groups for the respective condition. It is possible that continued exposure to assisted sprinting might allow the female team-sports players studied to adapt their coordination to the 'over-speed' condition and increase step frequency. It is notable that step-by-step kinematics in these sprints were easy to obtain using relatively inexpensive equipment with possibilities of direct feedback.

Ball-Sport Endurance and Sprint Test (BEAST90): validity and reliability of a 90-minute soccer performance test.

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Williams, Jeremy D; Abt, Grant; Kilding, Andrew E

2010-12-01

The aim of this study was to determine the validity and reliability of a 90-minute soccer performance test: Ball-sport Endurance and Sprint Test (BEAST90). Fifteen healthy male amateur soccer players participated and attended 5 testing sessions over a 10-day period to perform physiologic and soccer-specific assessments. This included familiarization sessions and 2 full trials of the BEAST90, separated by 7 days. The total 90-minute distance, mean percent peak heart rate (HRpeak), and estimated percent peak oxygen uptake of the BEAST90 were 8,097 ± 458 m, 85 ± 5% and 82 ± 14%, respectively. Measures obtained from trial 1 and trial 2 were not significantly different (p > 0.05). Reliability of measures over 90 minutes ranged from 0.9-25.5% (% typical error). The BEAST90 protocol replicated soccer match play in terms of time, movement patterns, physical demands (volume and intensity), distances, and mean and HRpeak values, as well as having an aerobic load similar to that observed during a soccer match. Reproducibility of key physical measures during the BEAST90 were mostly high, suggesting good reliability. The BEAST90 could be used in studies that wish to determine the effects of training or nutritional interventions on prolonged intermittent physical performance.

Short- or long-rest intervals during repeated-sprint training in soccer?

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Iaia, F. Marcello; Fiorenza, Matteo; Larghi, Luca; Alberti, Giampietro; Millet, Grégoire P.; Girard, Olivier

2017-01-01

The present study compared the effects of two repeated-sprint training (RST) programs, differing in duration of the between-sprint rest intervals, on various soccer-related exercise performances. For 5 weeks during the competitive season, twenty-nine young trained male soccer players either replaced two of their habitual fitness conditioning sessions with RST characterized by short (5–15; n = 9) or long (5–30; n = 10) rest intervals, or served as control (n = 10). The 5–15 and 5–30 protocols consisted of 6 repetitions of 30-m (~5 s) straight-line sprints interspersed with 15 s or 30 s of passive recovery, respectively. 5–15 improved 200-m sprint time (2.0±1.5%; pRecovery Test Level 2 increased following 5–15 (11.4±5.0%; psoccer players, RST over a 5-week in-season period is an efficient means to simultaneously develop different components of fitness relevant to match performance, with different benefits induced by shorter compared to longer rest intervals. PMID:28199402

Kinetic Sprint Asymmetries on a non-motorised Treadmill in Rugby Union Athletes.

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Brown, Scott R; Cross, Matt R; Girard, Olivier; Brocherie, Franck; Samozino, Pierre; Morin, Jean-Benoît

2017-11-01

The purpose of this study was to present a potential link between sprint kinetic (vertical [F V ] and horizontal force [F H ]) asymmetries and athletic performance during acceleration and maximal velocity (v max ) sprinting. Thirty un-injured male rugby athletes performed 8-s sprints on a non-motorised treadmill. Kinetic data were divided into 'strong' and 'weak' legs based on individually averaged peak values observed during sprinting and were analysed to evaluate asymmetry. Large differences were found between the strong and weak legs in F H during acceleration (4.3 vs. 3.5 N·kg -1 ) and v max (3.7 vs. 2.8 N·kg -1 ) sprinting (both ES=1.2), but not in F V (21.8 vs. 20.8 N·kg -1 , ES=- 0.6 for acceleration; 23.9 vs. 22.8 N·kg -1 , ES=- 0.5 for v max , respectively). Group mean asymmetry was lower in F V compared to F H during acceleration (1.6 vs. 6.8%) and v max (1.6 vs. 8.2%). The range of asymmetry was much lower in F V (0.03-4.3%) compared to F H (0.2-28%). In un-injured rugby athletes, the magnitude and range of asymmetry scores in F H , occurring during acceleration and v max phases, where much greater than those found in F V . These findings highlight the potential for some un-injured athletes to possess kinetic asymmetries known as crucial components for acceleration performance in sprinting. © Georg Thieme Verlag KG Stuttgart · New York.

Sprint vs. intermittent training in young female basketball players.

Science.gov (United States)

Attene, G; Pizzolato, F; Calcagno, G; Ibba, G; Pinna, M; Salernitano, G; Padulo, J

2014-04-01

This study aimed at comparing the effects of intermittent and repeated sprint ability training on physiological variables. Sixteen young female basketball players were randomly allocated to intermittent training (IT=8) or repeated sprint ability training (RST=8) groups. The following outcomes were measured at baseline and after 6 weeks of training: Yo-Yo intermittent recovery (Yo-Yo) and repeated sprint ability (RSA) tests. For all the variables investigated the effect of training type showed a different trend respect at current knowledge. In the RSA, best time (BT) was a significant main effect of training time (pre- vs. post-) (Ptraining type/time (P=0.03). The RST showed a decrease in BT of 3.1% (P=0.005) while the IT showed a decrease of 6.2% (Ptraining methods used in this study can be an effective training strategy for inducing anaerobic and basketball-specific training schedules. Besides, even when IT training is not done at very high speed, it can increase the maximum speed of the RSA.

Effects of combined creatine and sodium bicarbonate supplementation on repeated sprint performance in trained men.

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Barber, James J; McDermott, Ann Y; McGaughey, Karen J; Olmstead, Jennifer D; Hagobian, Todd A

2013-01-01

Creatine and sodium bicarbonate supplementation independently increase exercise performance, but it remains unclear whether combining these 2 supplements is more beneficial on exercise performance. The purpose of this study was to evaluate the impact of combining creatine monohydrate and sodium bicarbonate supplementation on exercise performance. Thirteen healthy, trained men (21.1 ± 0.6 years, 23.5 ± 0.5 kg·m(-2), 66.7 ± 5.7 ml·(kg·m)(-1) completed 3 conditions in a double-blinded, crossover fashion: (a) Placebo (Pl; 20 g maltodextrin + 0.5 g·kg(-1) maltodextrin), (b) Creatine (Cr; 20 g + 0.5 g·kg(-1) maltodextrin), and (c) Creatine plus sodium bicarbonate (Cr + Sb; 20 g + 0.5 g·kg(-1) sodium bicarbonate). Each condition consisted of supplementation for 2 days followed by a 3-week washout. Peak power, mean power, relative peak power, and bicarbonate concentrations were assessed during six 10-second repeated Wingate sprint tests on a cycle ergometer with a 60-second rest period between each sprint. Compared with Pl, relative peak power was significantly higher in Cr (4%) and Cr + Sb (7%). Relative peak power was significantly lower in sprints 4-6, compared with that in sprint 1, in both Pl and Cr. However, in Cr + Sb, sprint 6 was the only sprint significantly lower compared with sprint 1. Pre-Wingate bicarbonate concentrations were significantly higher in Cr + Sb (10%), compared with in Pl and Cr, and mean concentrations remained higher after sprint 6, although not significantly. Combining creatine and sodium bicarbonate supplementation increased peak and mean power and had the greatest attenuation of decline in relative peak power over the 6 repeated sprints. These data suggest that combining these 2 supplements may be advantageous for athletes participating in high-intensity, intermittent exercise.

FAMILIARISATION AND RELIABILITY OF SPRINT TEST INDICES DURING LABORATORY AND FIELD ASSESSMENT

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Andrew Galbraith

2009-12-01

Full Text Available The aim of the study was to assess the reliability of sprint performance in both field and laboratory conditions. Twenty-one male (mean ± s: 19 ± 1 years, 1.79 ± 0.07 m, 77.6 ± 7.1 kg and seventeen female team sport players (mean ± s: 21 ± 4 years, 1.68 ± 0. 07 m, 62.7 ± 4.7 kg performed a maximal 20-metre sprint running test on eight separate occasions. Four trials were conducted on a non-motorised treadmill in the laboratory; the other four were conducted outdoors on a hard-court training surface with time recorded by single-beam photocells. Trials were conducted in random order with no familiarisation prior to testing. There was a significant difference between times recorded during outdoor field trials (OFT and indoor laboratory trials (ILT using a non-motorised treadmill (3.47 ± 0.53 vs. 6.06 ±1.17s; p < 0.001. The coefficient of variation (CV for time was 2.55-4.22% for OFT and 5.1-7.2% for ILT. During ILT peak force (420.9 ± 87.7N, mean force (147.2 ± 24.7N, peak power (1376.8 ± 451.9W and mean power (514.8 ± 164.4W, and were measured. The CV for all ILT variables was highest during trial 1-2 comparison. The CV (95% confidence interval for the trial 3-4 comparison yielded: 9.4% (7.7-12. 1%, 7.9% (6.4-10.2%, 10.1% (8.2-13.1% and 6.2% (5.1-8.0% for PF, MF, PP and MP and respectively. The results indicate that reliable data can be derived for single maximal sprint measures, using fixed distance protocols. However, significant differences in time/speed over 20-m exist between field and laboratory conditions. This is primarily due to the frictional resistance in the non- motorised treadmill. Measures of force and power during ILT require at least 3 familiarisations to reduce variability in test scores

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.

Acute Ingestion of Caffeinated Chewing Gum Improves Repeated Sprint Performance of Team Sport Athletes With Low Habitual Caffeine Consumption.

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Evans, Mark; Tierney, Peter; Gray, Nicola; Hawe, Greg; Macken, Maria; Egan, Brendan

2018-04-23

The effects of acute ingestion of caffeine on short-duration high-intensity performance are equivocal, while studies of novel modes of delivery and the efficacy of low doses of caffeine are warranted. The aims of the present study were to investigate the effect of acute ingestion of caffeinated chewing gum on repeated sprint performance (RSP) in team sport athletes, and whether habitual caffeine consumption alters the ergogenic effect, if any, on RSP. A total of 18 male team sport athletes undertook four RSP trials using a 40-m maximum shuttle run test, which incorporates 10 × 40-m sprints with 30 s between the start of each sprint. Each participant completed two familiarization sessions, followed by caffeine (CAF; caffeinated chewing gum; 200 mg caffeine) and placebo (PLA; noncaffeinated chewing gum) trials in a randomized, double-blind manner. RSP, assessed by sprint performance decrement (%), did not differ (p = .209; effect size = 0.16; N = 18) between CAF (5.00 ± 2.84%) and PLA (5.43 ± 2.68%). Secondary analysis revealed that low habitual caffeine consumers (130 mg/day, n = 6; 3.98 ± 2.57% vs. 3.80 ± 1.79%, respectively; p = .684; effect size = 0.08). The data suggest that a low dose of caffeine in the form of caffeinated chewing gum attenuates the sprint performance decrement during RSP by team sport athletes with low, but not moderate-to-high, habitual consumption of caffeine.

Effect of 2 soccer matches in a week on physical performance and injury rate.

Science.gov (United States)

Dupont, Gregory; Nedelec, Mathieu; McCall, Alan; McCormack, Derek; Berthoin, Serge; Wisløff, Ulrik

2010-09-01

Recovery duration may be too short during the congested fixtures of professional soccer players with regard to maintaining physical performance and a low injury rate. To analyze the effects of 2 matches per week on physical performance and injury rate in male elite soccer players. Cohort study; Level of evidence, 3. Match results, match-related physical performance, and injuries were monitored during 2 seasons (2007-2008 and 2008-2009) for 32 professional soccer players in a top-level team participating in the UEFA (Union of European Football Associations) Champions League. Total distance, high-intensity distance, sprint distance, and number of sprints were collected for 52 home matches. Injuries and player participation in matches and training were recorded throughout the full season. Physical performance, as characterized by total distance covered, high-intensity distance, sprint distance, and number of sprints, was not significantly affected by the number of matches per week (1 versus 2), whereas the injury rate was significantly higher when players played 2 matches per week versus 1 match per week (25.6 versus 4.1 injuries per 1000 hours of exposure; P physical performance tested but is not long enough to maintain a low injury rate. The present data highlight the need for player rotation and for improved recovery strategies to maintain a low injury rate among athletes during periods with congested match fixtures.

Effects of Cycling Versus Running Training on Sprint and Endurance Capacity in Inline Speed Skating

Science.gov (United States)

Stangier, Carolin; Abel, Thomas; Mierau, Julia; Hollmann, Wildor; Strüder, Heiko K.

2016-01-01

The purpose of this study was to compare the effects of running versus cycling training on sprint and endurance capacity in inline speed skating. Sixteen elite athletes (8 male, 8 female, 24 ± 8 yrs) were randomly assigned into 2 training groups performing either 2 session per week of treadmill running or ergometer cycling in addition to 3 skating specific sessions (technique, plyometrics, parkour) for 8 weeks. Training intensity was determined within non-specific (cycling or running) and effects on specific endurance capacity within a specific incremental exercise test. Before and after the intervention all athletes performed a specific (300m) and one non-specific (30s cycling or 200m running) all-out sprint test according to the group affiliation. To determine the accumulation of blood lactate (BLa) and glucose (BGL) 20 μl arterialized blood was drawn at rest, as well as in 1 min intervals for 10 min after the sprint test. The sport-specific peak oxygen uptake (VO2 peak) was significantly increased (+17%; p = 0.01) in both groups and highly correlated with the sprint performance (r = -0.71). BLa values decreased significantly (-18%, p = 0.02) after the specific sprint test from pre to post-testing without any group effect. However, BGL values only showed a significant decrease (-2%, p = 0.04) in the running group. The close relationship between aerobic capacity and sprint performance in inline speed skating highlights the positive effects of endurance training. Although both training programs were equally effective in improving endurance and sprint capacities, the metabolic results indicate a faster recovery after high intensity efforts for all athletes, as well as a higher reliance on the fat metabolism for athletes who trained in the running group. Key points In addition to a highly developed aerobic performance inline speed skaters also require a highly trained anaerobic capacity to be effective in the sprint sections such as the mass start, tactical attacks

Determining friction and effective loading for sled sprinting.

Science.gov (United States)

Cross, Matt R; Tinwala, Farhan; Lenetsky, Seth; Samozino, Pierre; Brughelli, Matt; Morin, Jean-Benoit

2017-11-01

Understanding the impact of friction in sled sprinting allows the quantification of kinetic outputs and the effective loading experienced by the athlete. This study assessed changes in the coefficient of friction (µ k ) of a sled sprint-training device with changing mass and speed to provide a means of quantifying effective loading for athletes. A common sled equipped with a load cell was towed across an athletics track using a motorised winch under variable sled mass (33.1-99.6 kg) with constant speeds (0.1 and 0.3 m · s -1 ), and with constant sled mass (55.6 kg) and varying speeds (0.1-6.0 m · s -1 ). Mean force data were analysed, with five trials performed for each condition to assess the reliability of measures. Variables were determined as reliable (ICC > 0.99, CV friction-force and speed/coefficient of friction relationships well fitted with linear (R 2  = 0.994-0.995) and quadratic regressions (R 2  = 0.999), respectively (P friction values determined at two speeds, and the range in values from the quadratic fit (µ k  = 0.35-0.47) suggested µ k and effective loading were dependent on instantaneous speed on athletics track surfaces. This research provides a proof-of-concept for the assessment of friction characteristics during sled towing, with a practical example of its application in determining effective loading and sled-sprinting kinetics. The results clarify effects of friction during sled sprinting and improve the accuracy of loading applications in practice and transparency of reporting in research.

Dynamic factors and electromyographic activity in a sprint start

Directory of Open Access Journals (Sweden)

M Čoh

2009-07-01

Full Text Available The aim of the study was to establish the major dynamic parameters as well as the EMG activation of muscles in a sprint start as the first derivative of sprint velocity. The subject of the analysis was block velocity, the production of force in the front and rear starting blocks, the block acceleration in the first two steps and the electromyographic activity (EMG of the following muscles: the erector spinae muscle, gluteus maximus muscle, rectus femoris muscle, vastus medialis muscle, vastus lateralis muscle, biceps femoris muscle and gastrocnemius–medialis muscle. One international-class female sprinter participated in the experiment. She performed eight starts in constant laboratory conditions. The 3-D kinematic analysis was made using a system of nine Smart-e 600 cameras operating at a frame rate of 60 Hz. Dynamic parameters were established by means of two separate force platforms to which the starting blocks were fixed. A 16-channel electromyograph was used to analyse electromyographic activity (EMG. It was established that the block velocity depended on the absolute force produced in the front and rear starting blocks and that it was 2.84±0.21 m.s-1. The maximal force on the rear and front blocks was 628±34 N and 1023±30 N, respectively. In view of the total impulse (210±11 Ns the force production/time ratio in the rear and front blocks was 34%:66%. The erector spinae muscle, vastus lateralis muscle and gastrocnemius–medialis muscle generate the efficiency of the start. The block acceleration in the first two steps primarily depends on the activation of the gluteus maximus muscle, rectus femoris muscle, biceps femoris muscle and gastrocnemius–medialis muscle. A sprint start is a complex motor stereotype requiring a high degree of integration of the processes of central movement regulation and an optimal level of biomotor abilities.

Enhanced Strength and Sprint Levels, and Changes in Blood Parameters during a Complete Athletics Season in 800 m High-Level Athletes

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Beatriz Bachero-Mena

2017-08-01

Full Text Available The purpose of this study was to analyze changes in sprint, strength, hematological, and hormonal parameters in high-level 800 m athletes during a complete athletics season. Thirteen male athletes of national and international level in 800 m (personal best ranging from 1:43 to 1:58 min:ss participated in this study. A total of 5 tests were conducted during a complete athletics season. Athletes performed sprint tests (20 and 200 m, countermovement jump (CMJ, jump squat (JS, and full squat (SQ tests. Blood samples (red and white blood profile and hormones were collected in test 1 (T1, test 3 (T3, and test 5 (T5. A general increase in the performance of the strength and sprint parameters analyzed (CMJ, JS, SQ, 20 m, and 200 m during the season was observed, with a significant time effect in CMJ (P < 0.01, SQ (P < 0.01, and 200 m (P < 0.05. This improvement was accompanied by a significant enhancement of the 800 m performance from T3 to T5 (P < 0.01. Significant changes in some hematological variables: hematocrit (Hct (P < 0.01, mean corpuscular volume (MCV (P < 0.001, mean corpuscular hemoglobin content (MCHC (P < 0.001, white blood cells count (WBC (P < 0.05, neutrophils (P < 0.05, monocytes (P < 0.05, and mean platelet volume (MPV (P < 0.05 were observed throughout the season. The hormonal response and creatin kinase (CK did not show significant variations during the season, except for insulin-like growth factor I (IGF-1 (P < 0.05. In conclusion, our results suggest the importance of strength levels in middle-distance athletes. On the other hand, variations in some hematological parameters and a depression of the immune system occurred during the season. Therefore, monitoring of the mechanical, hematological and hormonal response in athletes may help coaches and athletes to optimize the regulation of training contents and may be useful to diagnose states of overreaching or overtraining in athletes throughout the season.

Pacing and sprint performance in speed skating during a competitive season.

Science.gov (United States)

Muehlbauer, Thomas; Schindler, Christian; Panzer, Stefan

2010-06-01

This study assessed the effect of time spent in several race sectors (S) on finishing time and determined the variance in distribution of skating time and in total race time for official 1000-m sprint races conducted during a competitive season. Total race and sector times for the first 200 m (S1) and the following two 400-m laps (S2 and S3) of 34 female and 31 male elite speed skaters performed during a series of World Cup Meetings were analyzed. Overall, skaters started fast, reached their peak in S2, and slowed down in S3, irrespective of race category considered (eg, rank of athlete, number of race, altitude of rink, starting lane). Regression analyses revealed that spending a shorter fraction of time in the last (women in S3: B = 239.1; P < .0001; men in S3: B = 201.5; P < .0001) but not in the first (women in S1: B = -313.1; P < .0001; men in S1: B = -345.6; P < .0001) race sector is associated with a short total race time. Upper- compared with lower-ranked skaters varied less in competition-to-competition sector and total race times (women: 0.02 to 0.33 vs 0.02 to 0.51; men: 0.01 to 0.15 vs 0.02 to 0.57). This study confirmed that skaters adopted a fast start pacing strategy during official 1000-m sprint races. However, analyses indicate that shortening time in the closing but not in the starting sector is beneficial for finishing fast. In addition, findings suggest that lower-ranked skaters should concentrate training on lowering their competition-to-competition variability in sector times.

Optimizing the physical conditioning of the NASCAR sprint cup pit crew athlete.

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Ferguson, David P; Davis, Adam M; Lightfoot, J Timothy

2015-03-01

Stock car racing is the largest spectator sport in the United States. As a result, National Association for Stock Car Automobile Racing (NASCAR) Sprint Cup teams have begun to invest in strength and conditioning programs for their pit crew athletes. However, there is limited knowledge regarding the physical characteristics of elite NASCAR pit crew athletes, how the NASCAR Sprint Cup season affects basic physiological parameters such as body composition, and what is the most appropriate physical training program that meets the needs of a pit crew athlete. We conducted 3 experiments involving Sprint Cup motorsport athletes to determine predictors of success at the elite level, seasonal physiological changes, and appropriate physical training programs. Our results showed that hamstring flexibility (p = 0.015) and the score on the 2-tire front run test (p = 0.012) were significant predictors of NASCAR Sprint Cup Pit Crew athlete performance. Additionally, during the off season, pit crew athletes lost lean body mass, which did not return until the middle of the season. Therefore, a strength and conditioning program was developed to optimize pit crew athlete performance throughout the season. Implementation of this strength and conditioning program in 1 NASCAR Sprint Cup team demonstrated that pit crew athletes were able to prevent lean body mass loss and have increased muscle power output from the start of the season to the end of the season.

SPRINT: A new parallel framework for R

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Scharinger Florian

2008-12-01

Full Text Available Abstract Background Microarray analysis allows the simultaneous measurement of thousands to millions of genes or sequences across tens to thousands of different samples. The analysis of the resulting data tests the limits of existing bioinformatics computing infrastructure. A solution to this issue is to use High Performance Computing (HPC systems, which contain many processors and more memory than desktop computer systems. Many biostatisticians use R to process the data gleaned from microarray analysis and there is even a dedicated group of packages, Bioconductor, for this purpose. However, to exploit HPC systems, R must be able to utilise the multiple processors available on these systems. There are existing modules that enable R to use multiple processors, but these are either difficult to use for the HPC novice or cannot be used to solve certain classes of problems. A method of exploiting HPC systems, using R, but without recourse to mastering parallel programming paradigms is therefore necessary to analyse genomic data to its fullest. Results We have designed and built a prototype framework that allows the addition of parallelised functions to R to enable the easy exploitation of HPC systems. The Simple Parallel R INTerface (SPRINT is a wrapper around such parallelised functions. Their use requires very little modification to existing sequential R scripts and no expertise in parallel computing. As an example we created a function that carries out the computation of a pairwise calculated correlation matrix. This performs well with SPRINT. When executed using SPRINT on an HPC resource of eight processors this computation reduces by more than three times the time R takes to complete it on one processor. Conclusion SPRINT allows the biostatistician to concentrate on the research problems rather than the computation, while still allowing exploitation of HPC systems. It is easy to use and with further development will become more useful as more

Sprint interval and sprint continuous training increases circulating CD34+ cells and cardio-respiratory fitness in young healthy women.

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Emma Harris

Full Text Available The improvement of vascular health in the exercising limb can be attained by sprint interval training (SIT. However, the effects on systemic vascular function and on circulating angiogenic cells (CACs which may contribute to endothelial repair have not been investigated. Additionally, a comparison between SIT and sprint continuous training (SCT which is less time committing has not been made.12 women (22±2 yrs completed 12 sessions of either SIT (n = 6 or work-matched SCT (n = 6 on 3 days/week. Pre and post-training assessments included brachial artery endothelial function and peripheral blood analysis for CAC number (CD34+/CD34+CD45dim. CAC function was measured by migration and adhesion assays. Cardio-respiratory fitness, carotid arterial stiffness and carotid-radial and brachial-foot pulse wave velocity (PWV were also evaluated.CD34+ CACs increased following training in both groups but CD34+CD45dim did not (Pre CD34+: 40±21/105 leukocytes, Post CD34+: 56±24/105 leukocytes, main time effect p0.05.SCT involving little time commitment is comparable to SIT in increasing CD34+ cell number and [Formula: see text]. An increased mobilisation of CD34+ CACs suggests that sprint training may be an effective method to enhance vascular repair.

An Analysis of Collaborative Problem-Solving Mechanisms in Sponsored Projects: Applying the 5-Day Sprint Model

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Raubenolt, Amy

2016-01-01

In May 2016, the office of Finance and Sponsored Projects at The Research Institute at Nationwide Children's Hospital conducted a 5-day design sprint session to re-evaluate and redesign a flawed final reporting process within the department. The department sprint was modeled after the design sprint sessions that occur routinely in software…

Low-Intensity Sprint Training With Blood Flow Restriction Improves 100-m Dash.

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Behringer, Michael; Behlau, Daniel; Montag, Johannes C K; McCourt, Molly L; Mester, Joachim

2017-09-01

Behringer, M, Behlau, D, Montag, JCK, McCourt, ML, and Mester, J. Low-intensity sprint training with blood flow restriction improves 100-m dash. J Strength Cond Res 31(9): 2462-2472, 2017-We investigated the effects of practical blood flow restriction (pBFR) of leg muscles during sprint training on the 100-m dash time in well-trained sport students. Participants performed 6 × 100-m sprints at 60-70% of their maximal 100-m sprinting speed twice a week for 6 weeks, either with (intervention group [IG]; n = 12) or without pBFR (control group [CG]; n = 12). The 100-m dash time significantly decreased more in the IG (-0.38 ± 0.24 seconds) than in the CG (-0.16 ± 0.17 seconds). The muscle thickness of the rectus femoris increased only in the IG, whereas no group-by-time interactions were found for the muscle thickness of the biceps femoris and the biceps brachii. The maximal isometric force, measured using a leg press, did not change in either group. However, the rate of force development improved in the IG. Growth hormone, testosterone, insulin-like growth factor 1, and cortisol concentrations did not significantly differ between both groups at any measurement time point (pre, 1 minute, 20 minutes, 120 minutes, and 24 hours after the 6 all-out sprints of the first training session). The muscle damage marker h-FABP increased significantly more in the CG than in the IG. The pBFR improved the 100-m dash time significantly more than low-intensity sprint interval training alone. Other noted benefits of training with pBFR were a decreased level of muscle damage, a greater increase of the rectus femoris muscle thickness, and a higher rate of force development. However, the tested hormones were unable to explain the additional beneficial effects.

Within-cycle characteristics of the wheelchair push in sprinting on a wheelchair ergometer

NARCIS (Netherlands)

Veeger, DirkJan (H. E. J.); van der Woude, L H; Rozendal, R H

To investigate power output and torque production in wheelchair sprinting, six able-bodied subjects performed nine 20-s sprint tests on a stationary wheelchair ergometer (load 0-8 kg). Ergometer data were analyzed and combined with kinematic data and surface electromyography. Of all power and torque

Adaptive Changes After 2 Weeks of 10-s Sprint Interval Training With Various Recovery Times

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Robert A. Olek

2018-04-01

Full Text Available Purpose: The aim of this study was to compare the effect of applying two different rest recovery times in a 10-s sprint interval training session on aerobic and anaerobic capacities as well as skeletal muscle enzyme activities.Methods: Fourteen physically active but not highly trained male subjects (mean maximal oxygen uptake 50.5 ± 1.0 mlO2·kg−1·min−1 participated in the study. The training protocol involved a series of 10-s sprints separated by either 1-min (SIT10:1 or 4-min (SIT10:4 of recovery. The number of sprints progressed from four to six over six sessions separated by 1–2 days rest. Pre and post intervention anthropometric measurements, assessment of aerobic, anaerobic capacity and muscle biopsy were performed. In the muscle samples maximal activities of citrate synthase (CS, 3-hydroxyacylCoA dehydrogenase (HADH, carnitine palmitoyl-transferase (CPT, malate dehydrogenase (MDH, and its mitochondrial form (mMDH, as well as lactate dehydrogenase (LDH were determined. Analysis of variance was performed to determine changes between conditions.Results: Maximal oxygen uptake improved significantly in both training groups, by 13.6% in SIT10:1 and 11.9% in SIT10:4, with no difference between groups. Wingate anaerobic test results indicated main effect of time for total work, peak power output and mean power output, which increased significantly and similarly in both groups. Significant differences between training groups were observed for end power output, which increased by 10.8% in SIT10:1, but remained unchanged in SIT10:4. Both training protocols induced similar increase in CS activity (main effect of time p < 0.05, but no other enzymes.Conclusion: Sprint interval training protocols induce metabolic adaptation over a short period of time, and the reduced recovery between bouts may attenuate fatigue during maximal exercise.

Acute and Post-Exercise Physiological Responses to High-Intensity Interval Training in Endurance and Sprint Athletes.

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Cipryan, Lukas; Tschakert, Gerhard; Hofmann, Peter

2017-06-01

The purpose of the presented study was to compare acute and post-exercise differences in cardiorespiratory, metabolic, cardiac autonomic, inflammatory and muscle damage responses to high-intensity interval exercise (HIIT) between endurance and sprint athletes. The study group consisted of sixteen highly-trained males (age 22.1 ± 2.5 years) participating in endurance (n = 8) or sprint (n = 8) sporting events. All the participants underwent three exercise sessions: short HIIT (work interval duration 30s), long HIIT (3min) and constant load exercise (CE). The exercise interventions were matched for mean power, total time and in case of HIIT interventions also for work-to-relief ratio. The acute cardiorespiratory (HR, V̇ O 2 , RER) and metabolic (lactate) variables as well as the post-exercise changes (up to 3 h) in the heart rate variability, inflammation (interleukin-6, leucocytes) and muscle damage (creatine kinase, myoglobin) were monitored. Endurance athletes performed exercise interventions with moderately (CE) or largely (both HIIT modes) higher mean V̇ O 2 . These differences were trivial/small when V̇ O 2 was expressed as a percentage of V̇ O 2max . Moderately to largely lower RER and lactate values were found in endurance athletes. Markers of cardiac autonomic regulation, inflammation and muscle damage did not reveal any considerable differences between endurance and sprint athletes. In conclusions, endurance athletes were able to perform both HIIT formats with increased reliance on aerobic metabolic pathways although exercise intensity was identical in relative terms for all the participants. However, other markers of the acute and early post-exercise physiological response to these HIIT interventions indicated similarities between endurance and sprint athletes.

Acute and Post-Exercise Physiological Responses to High-Intensity Interval Training in Endurance and Sprint Athletes

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Lukas Cipryan, Gerhard Tschakert, Peter Hofmann

2017-06-01

Full Text Available The purpose of the presented study was to compare acute and post-exercise differences in cardiorespiratory, metabolic, cardiac autonomic, inflammatory and muscle damage responses to high-intensity interval exercise (HIIT between endurance and sprint athletes. The study group consisted of sixteen highly-trained males (age 22.1 ± 2.5 years participating in endurance (n = 8 or sprint (n = 8 sporting events. All the participants underwent three exercise sessions: short HIIT (work interval duration 30s, long HIIT (3min and constant load exercise (CE. The exercise interventions were matched for mean power, total time and in case of HIIT interventions also for work-to-relief ratio. The acute cardiorespiratory (HR, V̇O2, RER and metabolic (lactate variables as well as the post-exercise changes (up to 3 h in the heart rate variability, inflammation (interleukin-6, leucocytes and muscle damage (creatine kinase, myoglobin were monitored. Endurance athletes performed exercise interventions with moderately (CE or largely (both HIIT modes higher mean V̇O2. These differences were trivial/small when V̇O2 was expressed as a percentage of V̇O2max. Moderately to largely lower RER and lactate values were found in endurance athletes. Markers of cardiac autonomic regulation, inflammation and muscle damage did not reveal any considerable differences between endurance and sprint athletes. In conclusions, endurance athletes were able to perform both HIIT formats with increased reliance on aerobic metabolic pathways although exercise intensity was identical in relative terms for all the participants. However, other markers of the acute and early post-exercise physiological response to these HIIT interventions indicated similarities between endurance and sprint athletes.

Oxidative stress response in trained men following repeated squats or sprints.

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Bloomer, Richard J; Falvo, Michael J; Fry, Andrew C; Schilling, Brian K; Smith, Webb A; Moore, Christopher A

2006-08-01

The purpose of this investigation was to measure the oxidative stress response to similarly matched work bouts of squat and sprint exercise. Twelve anaerobically trained men performed six 10-s sprints and, on a separate occasion, repeated barbell squats to approximately equal the amount of work performed during the sprints. Blood lactate, heart rate, and perceived exertion was measured before and following each exercise bout. Muscle soreness, muscle force, and creatine kinase activity was determined preexercise and through 48 h of recovery. Desmin cytoskeletal protein was determined via muscle biopsy of the vastus lateralis before and at 24 h following each exercise. Plasma protein carbonyls (PC) and malondialdehyde (MDA) were measured as biomarkers of oxidative stress. Heart rate and perceived exertion was not different between exercise sessions (P > 0.05), although lactate was higher following sprinting compared with squatting (P = 0.002). Muscle soreness was greater for squatting than sprinting (P = 0.003) and reached a peak immediately postexercise for both sessions (P = 0.0003). Muscle force was unaffected by either exercise session (P > 0.05), and creatine kinase activity was elevated to a similar extent following both sessions. Desmin-negative fibers were virtually nonexistent after either exercise bout, indicating no loss of this cytoskeletal protein. Neither PC nor MDA was affected by the exercise (P > 0.05). These results suggest that in anaerobically trained men, the oxidative stress and muscle injury response to similarly matched anaerobic exercise bouts is minimal, and not different between exercise modes. Furthermore, when compared with previous literature on untrained subjects, the response is significantly attenuated, possibly because of adaptations occurring as a result of chronic, strenuous anaerobic training.

Estimation of tensile force in the hamstring muscles during overground sprinting.

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Ono, T; Higashihara, A; Shinohara, J; Hirose, N; Fukubayashi, T

2015-02-01

The purpose of this study was to identify the period of the gait cycle during which the hamstring muscles were likely injured by estimating the magnitude of tensile force in each muscle during overground sprinting. We conducted three-dimensional motion analysis of 12 male athletes performing overground sprinting at their maximal speed and calculated the hamstring muscle-tendon length and joint angles of the right limb throughout a gait cycle during which the ground reaction force was measured. Electromyographic activity during sprinting was recorded for the biceps femoris long head, semitendinosus, and semimembranosus muscles of ipsilateral limb. We estimated the magnitude of tensile force in each muscle by using the length change occurred in the musculotendon and normalized electromyographic activity value. The study found a quick increase of estimated tensile force in the biceps femoris long head during the early stance phase of the gait cycle during which the increased hip flexion angle and ground reaction force occurred at the same time. This study provides quantitative data of tensile force in the hamstring muscles suggesting that the biceps femoris long head muscle is susceptible to a strain injury during the early stance phase of the sprinting gait cycle. © Georg Thieme Verlag KG Stuttgart · New York.

Sprint's Social Media Ninja Program: A Model for Teaching Consumer Relations

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Gilliland, Rebecca A.

2017-01-01

This study reviews the application of a new training model, Sprint's Social Media Ninja program, an innovative approach to using new media to initiate change. Sprint recognized change management must occur from employee ambassadors to relevant audiences including consumers and other employees. By teaching volunteer employees the strategic message…

Rock-dwelling lizards exhibit less sensitivity of sprint speed to increases in substrate rugosity.

Science.gov (United States)

Collins, Clint E; Self, Jessica D; Anderson, Roger A; McBrayer, Lance D

2013-06-01

Effectively moving across variable substrates is important to all terrestrial animals. The effects of substrates on lizard performance have ecological ramifications including the partitioning of habitat according to sprinting ability on different surfaces. This phenomenon is known as sprint sensitivity, or the decrease in sprint speed due to change in substrate. However, sprint sensitivity has been characterized only in arboreal Anolis lizards. Our study measured sensitivity to substrate rugosity among six lizard species that occupy rocky, sandy, and/or arboreal habitats. Lizards that use rocky habitats are less sensitive to changes in substrate rugosity, followed by arboreal lizards, and then by lizards that use sandy habitats. We infer from comparative phylogenetic analysis that forelimb, chest, and tail dimensions are important external morphological features related to sensitivity to changes in substrate rugosity. Copyright © 2013 Elsevier GmbH. All rights reserved.

Four weeks of running sprint interval training improves cardiorespiratory fitness in young and middle-aged adults.

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Willoughby, Taura N; Thomas, Matthew P L; Schmale, Matthew S; Copeland, Jennifer L; Hazell, Tom J

2016-01-01

The purpose of this study was to determine the effectiveness of a 4-week running sprint interval training protocol to improve both aerobic and anaerobic fitness in middle-aged adults (40-50 years) as well as compare the adaptations to younger adults (20-30 years). Twenty-eight inactive participants - 14 young 20-30-year-olds (n = 7 males) and 14 middle-aged 40-50-year-olds (n = 5 males) - completed 4 weeks of running sprint interval training (4 to 6, 30-s "all-out" sprints on a curved, self-propelled treadmill separated by 4 min active recovery performed 3 times per week). Before and after training, all participants were assessed for maximal oxygen consumption (VO2max), 2000 m time trial performance, and anaerobic performance on a single 30-s sprint. There were no interactions between group and time for any tested variable, although training improved relative VO2max (young = 3.9, middle-aged = 5.2%; P < 0.04), time trial performance (young = 5.9, middle-aged = 8.2%; P < 0.001), peak sprint speed (young = 9.3, middle-aged = 2.2%; P < 0.001), and average sprint speed (young = 6.8, middle-aged = 11.6%; P < 0.001) in both young and middle-aged groups from pre- to post-training on the 30-s sprint test. The current study demonstrates that a 4-week running sprint interval training programme is equally effective at improving aerobic and anaerobic fitness in younger and middle-aged adults.

Match-play activity profile in professional soccer players during official games and the relationship between external and internal load.

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Suarez-Arrones, L; Torreño, N; Requena, B; Sáez De Villarreal, E; Casamichana, D; Barbero-Alvarez, J C; Munguía-Izquierdo, D

2015-12-01

The aim was to quantify for the first time the physical and physiological profile of professional soccer players in official games using GPS and heart rate (HR) response. Thirty professional soccer players were investigated during a half in competitive club level matches (N.=348) using GPS devices. The relative total distance was 118.9±10.7 m∙min(-1) and player's Work-To-Rest Ratio was 2.1:1. Defenders covered the lowest total distance, while Second-Strikers (2(nd)S) and Wide-Midfielders (W-MD) traveled the greatest total distance. Defenders presented the lowest Work-To-Rest Ratio values. Playing position also impacted on all sprinting performance results, except in average sprint distance and time of sprint. The number of sprints and repeated-sprint sequences recorded by the W-MD and Strikers (S) were significantly greater than any other group. The average HR recorded was 87.1%HRmax and the relationship between the external and internal load value (Effindex) was 1.4 with significant differences in both between playing positions. W-MD recorded a significantly smaller average HR than any other group and Centre-Backs showed a significantly smaller Effindex value than any other group. Conversely, W-MD showed a significantly greater Effindex value than any other group, except the 2(nd)S. This study has verified a number of statistically significant differences between the different playing positions. Coaches should be focused on the specific physical and physiological requirements of the playing positions to optimize the training prescription in soccer. The relationships between external and internal load measures among position-specific indicates that players with less overall running performance during match-play were the worst in Effindex.

Book Sprint: A new model for rapid book authoring and content development

International Nuclear Information System (INIS)

Zennaro, M.; Canessa, E.; Fonda, C.; Belcher, M.; Flickenger, R.

2007-01-01

We discuss our experiences and successes with the new 'Book Sprint' methodology for use in rapid authoring and content development for technical books and documentation, using a distributed team and appropriate on-line collaborative technologies. A sprint begins by assembling a group of domain experts for a short period of time-intensive content creation. The outline, scope, and approximate length of the book are established, and key contributors are identified. This is followed by remote and distributed work over a period of a few months, focussing on the bulk of the book. The Sprint Book methodology has already been used in the 'Wireless Networking in the Developing World' and 'Bandwidth Optimization and Management' books. Both of these are freely available under a Creative Commons License. (author)

SPRINT RA 230: Methodology for knowledge based developments

International Nuclear Information System (INIS)

Wallsgrove, R.; Munro, F.

1991-01-01

SPRINT RA 230: A Methodology for Knowledge Based Developments, funded by the European Commission, was set up to investigate the use of KBS in the engineering industry. Its aim was to find out low KBS were currently used and what people's conceptions of them was, to disseminate current knowledge and to recommend further research into this area. A survey (by post and face to face interviews) was carried out under SPRINT RA 230 to investigate requirements for more intelligent software. In the survey we looked both at how people think about Knowledge Based Systems (KBS), what they find useful and what is not useful, and what current expertise problems or limitations of conventional software might suggest KBS solutions. (orig./DG)

The impact of dry-land sprint start training on the short track speed skating start.

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Haug, William B; Drinkwater, Eric J; Cicero, Nicholas J; Barthell, J Anthony; Chapman, Dale W

2017-05-05

This investigation sought to determine the effects of dry-land sprint start training on short track speed skating (STSS) start performance. Nine highly trained short track athletes completed a control period of normal STSS training followed by a four-week training intervention. Before and after the control and intervention periods, athletes performed three electronically timed dry-land and on-ice 14.43 m maximal sprint start efforts. The intervention consisted of two sprint sessions per week consisting of nine electronically timed 14.43 m dry-land sprint starts in addition to normal STSS training. The control period resulted in no substantial change in on-ice start performance (Mean Δ: -0.01 s, 95% Confidence Limits (CL): -0.08 to 0.05 s; Effect Size (ES): -0.05; Trivial) however, a small change was observed in dry-land start performance (Mean Δ: -0.07 s, 95% CL: -0.13 to -0.02 s; ES: -0.49). Following brief specific dry-land sprint start training a small improvement was observed in both on-ice (Mean Δ: -0.07 s, 95% CL: -0.13 to -0.01 s; ES: -0.33) and dry-land (Mean Δ: -0.04 s, 95% CL: -0.09 to 0.00 s; ES: -0.29) start performance. This investigation suggests STSS start performance can be improved through a brief dry-land sprint start training program.

The Influence of Serial Carbohydrate Mouth Rinsing on Power Output during a Cycle Sprint.

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Phillips, Shaun M; Findlay, Scott; Kavaliauskas, Mykolas; Grant, Marie Clare

2014-05-01

The objective of the study was to investigate the influence of serial administration of a carbohydrate (CHO) mouth rinse on performance, metabolic and perceptual responses during a cycle sprint. Twelve physically active males (mean (± SD) age: 23.1 (3.0) years, height: 1.83 (0.07) m, body mass (BM): 86.3 (13.5) kg) completed the following mouth rinse trials in a randomized, counterbalanced, double-blind fashion; 1. 8 x 5 second rinses with a 25 ml CHO (6% w/v maltodextrin) solution, 2. 8 x 5 second rinses with a 25 ml placebo (PLA) solution. Following mouth rinse administration, participants completed a 30 second sprint on a cycle ergometer against a 0.075 g·kg(-1) BM resistance. Eight participants achieved a greater peak power output (PPO) in the CHO trial, resulting in a significantly greater PPO compared with PLA (13.51 ± 2.19 vs. 13.20 ± 2.14 W·kg(-1), p 0.05). No significant between-trials difference was reported for fatigue index, perceived exertion, arousal and nausea levels, or blood lactate and glucose concentrations. Serial administration of a CHO mouth rinse may significantly improve PPO during a cycle sprint. This improvement appears confined to the first 5 seconds of the sprint, and may come at a greater relative cost for the remainder of the sprint. Key pointsThe paper demonstrates that repeated administration of a carbohydrate mouth rinse can significantly improve peak power output during a single 30 second cycle sprint.The ergogenic effect of the carbohydrate mouth rinse may relate to the duration of exposure of the oral cavity to the mouth rinse, and associated greater stimulation of oral carbohydrate receptors.The significant increase in peak power output with the carbohydrate mouth rinse may come at a relative cost for the remainder of the sprint, evidenced by non-significantly lower mean power output and a greater fatigue index in the carbohydrate vs. placebo trial.Serial administration of a carbohydrate mouth rinse may be beneficial for

Attentional and visual demands for sprint performance in non-fatigued and fatigued conditions : reliability of a repeated sprint test

NARCIS (Netherlands)

Reininga, Inge H. F.; Lemmink, Koen A. P. M.; Diercks, Ron L.; Buizer, Arina T.; Stevens, Martin

2010-01-01

Background: Physical performance measures are widely used to assess physical function, providing information about physiological and biomechanical aspects of motor performance. However they do not provide insight into the attentional and visual demands for motor performance. A figure-of-eight sprint

Relationship between Lower Limb Angular Kinematic Variables and the Effectiveness of Sprinting during the Acceleration Phase

Directory of Open Access Journals (Sweden)

Artur Struzik

2016-01-01

Full Text Available The ability to reach a high running velocity over a short distance is essential to a high playing performance in team games. The aim of this study was to determine the relationship between running time over a 10-meter section of a 30-meter sprint along a straight line and changes in the angle and angular velocity that were observed in the ankle, knee, and hip joints. The possible presence may help to optimize motion efficiency during acceleration sprint phase. Eighteen girls involved in team sports were examined in the study. The Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using the Noraxon MyoMotion system. Statistically significant relationships were found between running time over a 10-meter section and the kinematic variables of hip and ankle joints. An excessively large flexion in hip joints might have an unfavorable effect on running time during the acceleration phase. Furthermore, in order to minimize running time during the acceleration phase, stride should be maintained along a line (a straight line rather than from side to side. It is also necessary to ensure an adequate range of motion in the hip and ankle joints with respect to the sagittal axis.

Relationship between Lower Limb Angular Kinematic Variables and the Effectiveness of Sprinting during the Acceleration Phase.

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Struzik, Artur; Konieczny, Grzegorz; Stawarz, Mateusz; Grzesik, Kamila; Winiarski, Sławomir; Rokita, Andrzej

2016-01-01

The ability to reach a high running velocity over a short distance is essential to a high playing performance in team games. The aim of this study was to determine the relationship between running time over a 10-meter section of a 30-meter sprint along a straight line and changes in the angle and angular velocity that were observed in the ankle, knee, and hip joints. The possible presence may help to optimize motion efficiency during acceleration sprint phase. Eighteen girls involved in team sports were examined in the study. The Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using the Noraxon MyoMotion system. Statistically significant relationships were found between running time over a 10-meter section and the kinematic variables of hip and ankle joints. An excessively large flexion in hip joints might have an unfavorable effect on running time during the acceleration phase. Furthermore, in order to minimize running time during the acceleration phase, stride should be maintained along a line (a straight line) rather than from side to side. It is also necessary to ensure an adequate range of motion in the hip and ankle joints with respect to the sagittal axis.

Reduction in plasma leucine after sprint exercise is greater in males than in females

DEFF Research Database (Denmark)

Esbjörnsson, M; Rooyackers, O; Norman, B

2012-01-01

There is a pronounced gender difference in the accumulation of plasma ammonia after sprint exercise. Ammonia is a key intermediate in amino acid metabolism, which implies that gender-related differences in plasma and muscle amino acid concentrations after sprint exercise exist. To study this, three...

Ground Reaction Force and Cadence during Stationary Running Sprint in Water and on Land.

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Fontana, H de Brito; Ruschel, C; Haupenthal, A; Hubert, M; Roesler, H

2015-06-01

This study was aimed at analyzing the cadence (Cadmax) and the peak vertical ground reaction force (Fymax) during stationary running sprint on dry land and at hip and chest level of water immersion. We hypothesized that both Fymax and Cadmax depend on the level of immersion and that differences in Cadmax between immersions do not affect Fymax during stationary sprint. 32 subjects performed the exercise at maximum cadence at each immersion level and data were collected with force plates. The results show that Cadmax and Fymax decrease 17 and 58% from dry land to chest immersion respectively, with no effect of cadence on Fymax. While previous studies have shown similar neuromuscular responses between aquatic and on land stationary sprint, our results emphasize the differences in Fymax between environments and levels of immersion. Additionally, the characteristics of this exercise permit maximum movement speed in water to be close to the maximum speed on dry land. The valuable combination of reduced risk of orthopedic trauma with similar neuromuscular responses is provided by the stationary sprint exercise in water. The results of this study support the rationale behind the prescription of stationary sprinting in sports training sessions as well as rehabilitation programs. © Georg Thieme Verlag KG Stuttgart · New York.

The Effect of Acceleration Sprint and Zig-zag Drill Combination to Increase Students’ Speed and Agility

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Bana, O.; Mintarto, E.; Kusnanik, N. W.

2018-01-01

The purpose of this research is to analyze the following factors: (1) how far the effect of exercise acceleration sprint on the speed and agility (2) how much influence the zig-zag drill combination to the speed and agility (3) and is there any difference between the effects of exercise acceleration sprint and practice zig-zag drill combination of the speed and agility. This research is quantitative with quasi-experimental approach. The design of this study is matching only design.This study was conducted on 33 male students who take part in extracurricular and divided into 3 groups with 11 students in each group. Group 1 was given training of acceleration sprint, group 2 was given zig-zag training combination drills of conventional and exercises for group 3, for 8 weeks. The data collection was using sprint 30 meter to test the speed and agility t-test to test agility. Data were analyzed using t-test and analysis of variance. The conclusion of the research is (1) there is a significant effect of exercise acceleration sprint for the speed and agility, (2) there is a significant influence combination zig-zag drills, on speed and agility (3) and exercise acceleration sprint have more effect on the speed and agility.

TO COMPARE THE EFFECTS OF SPRINT AND PLYOMETRIC TRAINING PROGRAM ON ANAEROBIC POWER AND AGILITY IN COLLEGIATE MALE FOOTBALL PLAYERS

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K. Vadivelan

2015-06-01

Full Text Available Background: Football is the world’s most popular game and is played by men, women and children of all ages and levels of ability. Success as a player requires an appropriate mixture of mental, physical, technical and tactical ability. Many decisive moments are defined by anaerobic activities such as sprinting, jumping & contests for the football. Agility is an ability of the neuromuscular system to coordinate explosive changes of direction of an individual and/or multiple body segments in all planes of motion. Plyometric Training has been advocated for sports that require the athletes to have explosive power and agility. Similarly previous sprint training studies have shown improvement in the dynamic athletic lower body performance. Advanced technique such as plyometric training protocol has proven more effective but not much studies have been done to assess its effectiveness over Plyometric Training, namely Lower Body Power and Agility Methods: A total of 30 collegiate football players were taken with a mean age of 21.5 with a standard deviation of one. They were randomized into two groups (Group A – Sprint Training & Group B – Plyometric Training. Each group consist of 15 players were selected based on their selection criteria. Informed consent was obtained from the subjects. The study was conducted for six weeks (12 sessions with both the Groups. Evolution parameters are vertical jump height, 40 yard dash, illinois agility Test. Results: Independent t test was used to analysis data. On comparing VJH, Plyometric Training shows (49.26 which have the higher mean value is more effective than Sprint Training (44.93.On comparing Anaerobic power Plyometric Training shows (4150.8 which has the higher Mean value is more effective than Sprint Training (3782.4, on comparing 40 yard dash Plyometric Training shows (5.335 which has the lower Mean value is more effective than Sprint Training (5.490. Illinois Agility Test Plyometric Training shows (15

A Comparison of Isometric Midthigh-Pull Strength, Vertical Jump, Sprint Speed, and Change-of-Direction Speed in Academy Netball Players.

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Thomas, Christopher; Comfort, Paul; Jones, Paul A; Dos'Santos, Thomas

2017-08-01

To investigate the relationships between maximal isometric strength, vertical jump (VJ), sprint speed, and change-of-direction speed (CoDS) in academy netball players and determine whether players who have high performance in isometric strength testing would demonstrate superior performance in VJ, sprint speed, and CoDS measures. Twenty-six young female netball players (age 16.1 ± 1.2 y, height 173.9 ± 5.7 cm, body mass 66.0 ± 7.2 kg) from a regional netball academy performed isometric midthigh pull (IMTP), squat jumps (SJs), countermovement jumps (CMJs), 10-m sprints, and CoDS (505). IMTP measures displayed moderate to strong correlations with sprint and CoDS performance (r = -.41 to -.66). The VJs, which included SJs and CMJs, demonstrated strong correlations with 10-m sprint times (r = -.60 to -.65; P strength to enhance VJ, sprint, and CoDS performance in youth netball players, with stronger athletes demonstrating superior VJ, sprint, and CoDS performances.

The effect of hamstring flexibility on peak hamstring muscle strain in sprinting

OpenAIRE

Xianglin Wan; Feng Qu; William E. Garrett; Hui Liu; Bing Yu

2017-01-01

Background: The effect of hamstring flexibility on the peak hamstring muscle strains in sprinting, until now, remained unknown, which limited our understanding of risk factors of hamstring muscle strain injury (hamstring injury). As a continuation of our previous study, this study was aimed to examine the relationship between hamstring flexibility and peak hamstring muscle strains in sprinting. Methods: Ten male and 10 female college students participated in this study. Hamstring flexibili...

Shuttle-Run Sprint Training in Hypoxia for Youth Elite Soccer Players: A Pilot Study

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Hannes Gatterer

2014-12-01

Full Text Available The purposes of the present study were to investigate if a shuttle-run sprint training performed in a normobaric hypoxia chamber of limited size (4.75x2.25m is feasible, in terms of producing the same absolute training load, when compared to training in normoxia, and b if such training improves the repeated sprint ability (RSA and the Yo-Yo intermittent recovery (YYIR test outcome in young elite soccer players. Players of an elite soccer training Centre (age: 15.3 ± 0.5 years, height: 1.73 ± 0.07 m, body mass: 62.6 ± 6.6 kg were randomly assigned to a hypoxia or a normoxia training group. Within a 5-week period, players, who were not informed about the hypoxia intervention, performed at least 7 sessions of identical shuttle-run sprint training either in a normal training room (FiO2 = 20.95% or in a hypoxic chamber (FiO2 = 14.8%; approximately 3300m, both equipped with the same floor. Each training session comprised 3 series of 5x10s back and forth sprints (4.5m performed at maximal intensity. Recovery time between repetitions was 20s and between series 5min. Before and after the training period the RSA (6 x 40m shuttle sprint with 20 s rest between shuttles and the YYIR test were performed. The size of the chamber did not restrict the training intensity of the sprint training (both groups performed approximately 8 shuttles during 10s. Training in hypoxia resulted in a lower fatigue slope which indicates better running speed maintenance during the RSA test (p = 0.024. YYIR performance increased over time (p = 0.045 without differences between groups (p > 0.05. This study showed that training intensity of the shuttle-run sprint training was not restricted in a hypoxic chamber of limited size which indicates that such training is feasible. Furthermore, hypoxia compared to normoxia training reduced the fatigue slope during the RSA test in youth soccer players.

Effects of Cycling Versus Running Training on Sprint and Endurance Capacity in Inline Speed Skating

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Carolin Stangier, Thomas Abel, Julia Mierau, Wildor Hollmann, Heiko K. Strüder

2016-03-01

Full Text Available The purpose of this study was to compare the effects of running versus cycling training on sprint and endurance capacity in inline speed skating. Sixteen elite athletes (8 male, 8 female, 24 ± 8 yrs were randomly assigned into 2 training groups performing either 2 session per week of treadmill running or ergometer cycling in addition to 3 skating specific sessions (technique, plyometrics, parkour for 8 weeks. Training intensity was determined within non-specific (cycling or running and effects on specific endurance capacity within a specific incremental exercise test. Before and after the intervention all athletes performed a specific (300m and one non-specific (30s cycling or 200m running all-out sprint test according to the group affiliation. To determine the accumulation of blood lactate (BLa and glucose (BGL 20 μl arterialized blood was drawn at rest, as well as in 1 min intervals for 10 min after the sprint test. The sport-specific peak oxygen uptake (VO2 peak was significantly increased (+17%; p = 0.01 in both groups and highly correlated with the sprint performance (r = -0.71. BLa values decreased significantly (-18%, p = 0.02 after the specific sprint test from pre to post-testing without any group effect. However, BGL values only showed a significant decrease (-2%, p = 0.04 in the running group. The close relationship between aerobic capacity and sprint performance in inline speed skating highlights the positive effects of endurance training. Although both training programs were equally effective in improving endurance and sprint capacities, the metabolic results indicate a faster recovery after high intensity efforts for all athletes, as well as a higher reliance on the fat metabolism for athletes who trained in the running group.

The effect of 8-week plyometric training on leg power, jump and sprint performance in female soccer players.

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Ozbar, Nurper; Ates, Seda; Agopyan, Ani

2014-10-01

The aim of this study was to determine the effect of 8-week plyometric training (PT) on the leg power and jump and sprint performance in female soccer players. Eighteen female soccer players from Women Second League (age = 18.2 ± 2.3 years, height = 161.3 ± 5.4 cm, body mass = 56.6 ± 7.2 kg) were randomly assigned to control (n = 9) and plyometric (n = 9) groups. Both groups continued together with regular technical and tactical soccer training for 4 days a week. Additionally, the plyometric group underwent PT for 8 weeks, 1 day per week, 60-minute session duration. During the 8-week period, the control group was hindered from any additional conditioning training. All players' jumps (triple hop, countermovement jump, and standing broad jump), running speed (20 m), and peak power were evaluated before and after 8 weeks. No significant difference was found between the groups at pretest variables (p > 0.05). Significant improvements were found in the posttest of both the groups (p ≤ 0.05), except for 20-m sprint test in the control group (p > 0.05). Triple hop distance, countermovement jump, standing broad jump, peak power, and 20-m sprint test values were all significantly improved in the plyometric group, compared with the control group (p ≤ 0.05). We concluded that short duration PT is an improved important component of athletic performance in female soccer players. The results indicate that safe, effective, and alternative PT can be useful to strength and conditioning coaches, especially during competition season where less time is available for training.

Percentile Values for Running Sprint Field Tests in Children Ages 6-17 Years: Influence of Weight Status

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Castro-Pinero, Jose; Gonzalez-Montesinos, Jose Luis; Keating, Xiaofen D.; Mora, Jesus; Sjostrom, Michael; Ruiz, Jonatan R.

2010-01-01

The aim of this study was to provide percentile values for six different sprint tests in 2,708 Spanish children (1,234 girls) ages 6-17.9 years. We also examined the influence of weight status on sprint performance across age groups, with a focus on underweight and obese groups. We used the 20-m, 30-m, and 50-m running sprint standing start and…

The effects of maturation on jumping ability and sprint adaptations to plyometric training in youth soccer players.

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Asadi, Abbas; Ramirez-Campillo, Rodrigo; Arazi, Hamid; Sáez de Villarreal, Eduardo

2018-04-03

The aim of this study was to investigate the effects of maturation on power and sprint performance adaptations following 6 weeks of plyometric training in youth soccer players during pre-season. Sixty male soccer players were categorized into 3 maturity groups (Pre, Mid and Post peak height velocity [PHV]) and then randomly assigned to plyometric group and control group. Vertical jump, standing long jump, and 20-m sprint (with and without ball) tests were collected before- and after-intervention. After the intervention, the Pre, Mid and Post-PHV groups showed significant (P ≤ 0.05) and small to moderate effect size (ES) improvement in vertical jump (ES = 0.48; 0.57; 0.73), peak power output (E = 0.60; 0.64; 0.76), standing long jump (ES = 0.62; 0.65; 0.7), 20-m sprint (ES = -0.58; -0.66), and 20-m sprint with ball (ES = -0.44; -0.8; -0.55) performances. The Post-PHV soccer players indicated greater gains than Pre-PHV in vertical jump and sprint performance after training (P ≤ 0.05). Short-term plyometric training had positive effects on sprinting and jumping-power which are important determinants of match-winning actions in soccer. These results indicate that a sixty foot contact, twice per week program, seems effective in improving power and sprint performance in youth soccer players.

The Influence of Serial Carbohydrate Mouth Rinsing on Power Output during a Cycle Sprint

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Shaun M. Phillips, Scott Findlay, Mykolas Kavaliauskas, Marie Clare Grant

2014-06-01

Full Text Available The objective of the study was to investigate the influence of serial administration of a carbohydrate (CHO mouth rinse on performance, metabolic and perceptual responses during a cycle sprint. Twelve physically active males (mean (± SD age: 23.1 (3.0 years, height: 1.83 (0.07 m, body mass (BM: 86.3 (13.5 kg completed the following mouth rinse trials in a randomized, counterbalanced, double-blind fashion; 1. 8 x 5 second rinses with a 25 ml CHO (6% w/v maltodextrin solution, 2. 8 x 5 second rinses with a 25 ml placebo (PLA solution. Following mouth rinse administration, participants completed a 30 second sprint on a cycle ergometer against a 0.075 g·kg-1 BM resistance. Eight participants achieved a greater peak power output (PPO in the CHO trial, resulting in a significantly greater PPO compared with PLA (13.51 ± 2.19 vs. 13.20 ± 2.14 W·kg-1, p 0.05. No significant between-trials difference was reported for fatigue index, perceived exertion, arousal and nausea levels, or blood lactate and glucose concentrations. Serial administration of a CHO mouth rinse may significantly improve PPO during a cycle sprint. This improvement appears confined to the first 5 seconds of the sprint, and may come at a greater relative cost for the remainder of the sprint.

Exploiting parallel R in the cloud with SPRINT.

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Piotrowski, M; McGilvary, G A; Sloan, T M; Mewissen, M; Lloyd, A D; Forster, T; Mitchell, L; Ghazal, P; Hill, J

2013-01-01

Advances in DNA Microarray devices and next-generation massively parallel DNA sequencing platforms have led to an exponential growth in data availability but the arising opportunities require adequate computing resources. High Performance Computing (HPC) in the Cloud offers an affordable way of meeting this need. Bioconductor, a popular tool for high-throughput genomic data analysis, is distributed as add-on modules for the R statistical programming language but R has no native capabilities for exploiting multi-processor architectures. SPRINT is an R package that enables easy access to HPC for genomics researchers. This paper investigates: setting up and running SPRINT-enabled genomic analyses on Amazon's Elastic Compute Cloud (EC2), the advantages of submitting applications to EC2 from different parts of the world and, if resource underutilization can improve application performance. The SPRINT parallel implementations of correlation, permutation testing, partitioning around medoids and the multi-purpose papply have been benchmarked on data sets of various size on Amazon EC2. Jobs have been submitted from both the UK and Thailand to investigate monetary differences. It is possible to obtain good, scalable performance but the level of improvement is dependent upon the nature of the algorithm. Resource underutilization can further improve the time to result. End-user's location impacts on costs due to factors such as local taxation. Although not designed to satisfy HPC requirements, Amazon EC2 and cloud computing in general provides an interesting alternative and provides new possibilities for smaller organisations with limited funds.

MONITORING SWIMMING SPRINT PERFORMANCE DURING A TRAINING CYCLE

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Daniel A. Marinho

2009-12-01

Full Text Available The preparation for a major competition is an important concern of coaches and athletes. Therefore, the aim of this study was to evaluate the evolution in sprint performance during a training macro cycle in age-group swimmers of both genders. The sample comprised twenty four age-group swimmers (12.0 ± 0.72 years old, 41.43 ± 6.88 kg, 1.51 ± 0.09 m. The evaluations occurred during nine weeks of swimming training in the first macro cycle. During this period the subjects performed 54 training units (6 units per week. In all weeks, the performance in two trials of a 25 m front crawl all out test, with 15 min of rest, was recorded. Only the bestperformance was used to assess the effects of training. Comparisons between the first week and the following weeks were conducted using pair-sample t-test. The significance level was set at 5%. The sprint performance did not change during the first 6 weeks of preparation. In the last three weeks the performance in the 25 m front crawl test was improved when compared with the first week, although the major changes occurred at the last week of preparation.It seems that in age-group swimmers seven weeks of specific swimming training enables improving swimmer’s sprint performance, although some differences exists between male and female swimmers. Thesedata could be used by coaches to program the training season and the evolution of the load components.

Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body.

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van der Zwaard, Stephan; van der Laarse, Willem J; Weide, Guido; Bloemers, Frank W; Hofmijster, Mathijs J; Levels, Koen; Noordhof, Dionne A; de Koning, Jos J; de Ruiter, Cornelis J; Jaspers, Richard T

2018-04-01

Optimizing physical performance is a major goal in current physiology. However, basic understanding of combining high sprint and endurance performance is currently lacking. This study identifies critical determinants of combined sprint and endurance performance using multiple regression analyses of physiologic determinants at different biologic levels. Cyclists, including 6 international sprint, 8 team pursuit, and 14 road cyclists, completed a Wingate test and 15-km time trial to obtain sprint and endurance performance results, respectively. Performance was normalized to lean body mass 2/3 to eliminate the influence of body size. Performance determinants were obtained from whole-body oxygen consumption, blood sampling, knee-extensor maximal force, muscle oxygenation, whole-muscle morphology, and muscle fiber histochemistry of musculus vastus lateralis. Normalized sprint performance was explained by percentage of fast-type fibers and muscle volume ( R 2 = 0.65; P body.

Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase

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Martínez-Valencia María Asunción

2015-06-01

Full Text Available Resisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak, a peak rate of force development (RFDpeak and time to RFD (TRFD in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001 in sprint times (20 and 30 m sprint for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s−1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s−1, p ≤ 0.01. Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration.

The Effects of Psoas Major and Lumbar Lordosis on Hip Flexion and Sprint Performance

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Copaver, Karine; Hertogh, Claude; Hue, Olivier

2012-01-01

In this study, we analyzed the correlations between hip flexion power, sprint performance, lumbar lordosis (LL) and the cross-sectional area (CSA) of the psoas muscle (PM). Ten young adults performed two sprint tests and isokinetic tests to determine hip flexion power. Magnetic resonance imaging was used to determine LL and PM CSA. There were…

Muscle power and repeated sprint ability in soccer players DOI: 10.5007/1980-0037.2010v12n4p255

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Juliano Dal Pupo

2010-01-01

Full Text Available Muscle power is one of the most important physical qualities of soccer player performance and needs to be maintained during a match. Thus, the aim of this study was to investigate the levels of muscle power in soccer players before and after performing repeated sprints (RS, and the association between power and RS performance. Twenty soccer players from the under-20 category aged 18-20 years participated in this study. The study consisted of the execution of vertical jumps, execution of RS, new execution of vertical jumps, and collection of blood samples. The continuous jump (CJ test was performed on a piezoelectric force platform for the measurement of muscle power and the RAST test was used to evaluate RS ability. No significant difference in the levels of muscle power was observed after RS (p=0.57. Significant differences were observed in the first to fifth sprint times (p< 0.01, but not between the fifth and sixth sprint (p=0.06. CJ height before RS was correlated with first sprint time (r=-0.62, p< 0.01, best sprint time (r=-0.60, p< 0.01, and average sprint time (r= -0.54, p<0.01. In conclusion, the soccer players studied showed no significant reduction in muscle power after RS. A decrease in performance was observed from the first to the fifth sprint, but not between the fifth and sixth sprint. The muscle power of soccer players was a determinant factor to perform one maximum sprint, as well as successive sprints.

Jumping and Hopping in Elite and Amateur Orienteering Athletes and Correlations to Sprinting and Running

DEFF Research Database (Denmark)

Hébert-Losier, Kim; Jensen, Kurt; Holmberg, Hans-Christer

2014-01-01

PURPOSE: Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlatio...... and rapid generation of high relative maximal forces, especially vertically. These functional measures were more closely related to sprinting and/or running abilities, indicating benefits of lower-body training in orienteering.......PURPOSE: Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlations...... with sprinting and/or running have been examined in orienteering athletes. METHODS: We investigated squat jump (SJ), countermovement jump (CMJ), standing long jump (SLJ), and hopping performed by 8 elite and 8 amateur male foot-orienteering athletes (29 ± 7 y, 183 ± 5 cm, 73 ± 7 kg) and possible correlations...

Effect of squatting on sprinting performance and repeated exposure to complex training in male rugby players.

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Comyns, Thomas M; Harrison, Andrew J; Hennessy, Liam K

2010-03-01

This study was undertaken to examine the effect of a heavy weight training exercise on sprinting performance and on the effect of repeated exposure to a complex training protocol. Eleven male rugby union players (age 20.9 +/- 3.1 years) participated in the study, which involved 5 separate testing sessions. Back squat 3 repetition maximum (3RM) was established in session 1. Sessions 2-5 were identical and involved the subjects completing a 30-m sprint before and after a 3RM back squat protocol. Four minutes of rest was given between the back squatting and the posttest 30-m sprint. All sprint trials were measured with a laser measurement device (LAVEG, Jenoptik, Jena, Germany). Sprint time and instantaneous, average, and maximum velocity were the dependent variables. The criterion for significance was set at an alpha level of p > or = 0.05. No significant improvement was evident for any of the testing sessions (p > or = 0.05). In session 1, there was a significant increase in 30-m time and a significant reduction in average 30-m velocity and maximum velocity (p benefits in sprinting may not have been realized because of intra and intersubject variations in sprint technique. The session x phase interaction revealed a significant improvement in the pre to posttest changes in instantaneous velocity at 20 m (p = 0.035) and 30 m (p = 0.036) from session 1 to session 4. This indicates that the rugby players may be able to learn to apply the potentiation effects of complex training. From a practical perspective, players may need repeated exposure to this training modality to gain benefit from it, and this should be reflected in program planning.

Effects of Plyometric and Sprint Training on Physical and Technical Skill Performance in Adolescent Soccer Players.

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Sáez de Villarreal, Eduardo; Suarez-Arrones, Luis; Requena, Bernardo; Haff, Gregory G; Ferrete, Carlos

2015-07-01

To determine the influence of a short-term combined plyometric and sprint training (9 weeks) within regular soccer practice on explosive and technical actions of pubertal soccer players during the in-season. Twenty-six players were randomly assigned to 2 groups: control group (CG) (soccer training only) and combined group (CombG) (plyometric + acceleration + dribbling + shooting). All players trained soccer 4 times per week and the experimental groups supplemented the soccer training with a proposed plyometric-sprint training program for 40 minutes (2 days per weeks). Ten-meter sprint, 10-m agility with and without ball, CMJ and Abalakov vertical jump, ball-shooting speed, and Yo-Yo intermittent endurance test were measured before and after training. The experimental group followed a 9-week plyometric and sprint program (i.e., jumping, hurdling, bouncing, skipping, and footwork) implemented before the soccer training. Baseline-training results showed no significant differences between the groups in any of the variables tested. No improvement was found in the CG; however, meaningful improvement was found in all variables in the experimental group: CMJ (effect size [ES] = 0.9), Abalakov vertical jump (ES = 1.3), 10-m sprint (ES = 0.7-0.9), 10-m agility (ES = 0.8-1.2), and ball-shooting speed (ES = 0.7-0.8). A specific combined plyometric and sprint training within regular soccer practice improved explosive actions compared with conventional soccer training only. Therefore, the short-term combined program had a beneficial impact on explosive actions, such as sprinting, change of direction, jumping, and ball-shooting speed which are important determinants of match-winning actions in soccer performance. Therefore, we propose modifications to current training methodology for pubertal soccer players to include combined plyometric and speed training for athlete preparation in this sport.

Analysis of Surface Dose Refer to Distance between Beam Spoiler and Patient in Total Body Irradiation

International Nuclear Information System (INIS)

Choi, Jong Hwan; Kim, Jong Sik; Choi, Ji Min; Shin, Eun Hyuk; Song, Ki Won; Park, Young Hwan

2007-01-01

Total body irradiation is used to kill the total malignant cell and for immunosuppression component of preparatory regimens for bone-marrow restitution of patients. Beam spoiler is used to increase the dose to the superficial tissues. This paper finds the property of the distance between beam spoiler and patient. Set-up conditions are 6 MV-Xray, 300 MU, SAD = 400 cm, field size = 40 x 40 cm 2 . The parallel plate chamber located in surface, midpoint and exit of solid water phantom. The surface dose is measured while the distance between beam spoiler and patient is altered. Because it should be found proper distance. The solid water phantom is fixer and beam spoiler is moving. Central dose of phantom is 10.7 cGy and exit dose is 6.7 cGy. In case of distance of 50 cm to 60 cm between beam spoiler and solid water phantom, incidence dose is 14.58-14.92 cGy. Therefore, The surface dose was measured 99.4-101% with got near most to the prescription dose. In clinical case, distance between beam spoiler and patient affect surface dose. If once 50-60 cm of distance between beam spoiler and patient, surface dose of patient got near prescription dose. It would be taken distance between beam spoiler and patient into account in clinical therapy.

Validation of the short posttraumatic stress disorder rating interview (SPRINT-E in a sample of people affected by F-27 Chilean earthquake and tsunami

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Marcelo C. Leiva-Bianchi

2013-05-01

Full Text Available On February 27, 2010 (F-27 there was an earthquake and a tsunami m Chile that has caused a great impact on the mental health of the population of this country, specifically in the increase of cases of posttraumatic stress disorder (PTSD. In view of count better instruments to measure PTSD was applied for the first time since it was created, the SPRINTE scale in a population other than the U.S., specifically in 291 people who experienced the F-27. The analysis of reliability (α=. 916, concurrent validity (all items significantly correlated with the scale used as a criterion DTS and construct validity (CMIN=2.237, RMSEA=.092, NFI=.901, CFI=.942 and PNFI=.704 for two-factor model indicate that SPRINT-E is a valid and reliable scale to measure PTSD in this population. Finally, some reflections about new factor structure discovered in this analysis, which is consistent with the meaning of items and with theoretical models such as covert stimuli. It also reflects on the usefulness of a brief scale, proven valid and very good psychometric characteristics in a Spanish-speaking population prone to natural disasters such as Chilean F-27, Japan (March 11, 2011 or Spain (May 11, 2011.

Determinants of a simulated cross-country skiing sprint competition using V2 skating technique on roller skis.

Science.gov (United States)

Mikkola, Jussi; Laaksonen, Marko; Holmberg, Hans-Christer; Vesterinen, Ville; Nummela, Ari

2010-04-01

The present study investigated the performance-predicting factors of a simulated cross-country (XC) skiing sprint competition on roller skis, on a slow surface. Sixteen elite male XC skiers performed a simulated sprint competition (4 x 850 m heat with a 20-minute recovery) using V2 skating technique on an indoor tartan track. Heat velocities, oxygen consumption, and peak lactate were measured during or after the heats. Maximal skiing velocity was measured by performing a 30-m speed test. Explosive and maximal force production in the upper body was determined by bench press (BP). Subjects also performed maximal anaerobic skiing test (MAST) and the 2 x 2-km double poling (DP) test. The maximal velocity of MAST (VMAST) and velocities at 3 (V3), 5 (V5), 7 (V7) mmol.L lactate levels in MAST were determined. In the 2 x 2-km test, DP economy (VO2SUBDP) and maximal 2-km DP velocity (VDP2KM) were determined. The best single performance-predicting factors for the sprint performance were VDP2KM (r = 0.73, p < 0.01), V7 (r = 0.70, p < 0.01), and VO2SUBDP (r = -0.70, p < 0.01). Faster skiers in sprint simulation had a higher absolute VO2 (L.min) (p < 0.05-0.01) during sprint heats, and higher anaerobic skiing power (VMAST, p < 0.05) and better anaerobic skiing economy (V3, V5, V7, p < 0.05-0.001) than slower skiers. Faster skiers were also stronger in BP, with regard to both absolute (p < 0.01) and relative (p < 0.05) values. In addition, anaerobic characteristics seem to be of importance at the beginning of the XC skiing sprint competition, whereas the aerobic characteristics become more important as the XC skiing sprint competition progressed. This study indicates that sprint skiers should emphasize sport-specific upper body training, and training skiing economy at high speeds.

The Characteristics of Static Plantar Loading in the First-Division College Sprint Athletes

OpenAIRE

Tong-Hsien Chow

2016-01-01

Background: Plantar pressure measurement is an effective method for assessing plantar loading and can be applied to evaluating movement performance of the foot. The purpose of this study is to explore the sprint athletes' plantar loading characteristics and pain profiles in static standing. Methods: Experiments were undertaken on 80 first-division college sprint athletes and 85 healthy non-sprinters. 'JC Mat', the optical plantar pressure measurement was applied to examining the differences b...

Effect of the coefficient of friction of a running surface on sprint time in a sled-towing exercise.

Science.gov (United States)

Linthorne, Nicholas P; Cooper, James E

2013-06-01

This study investigated the effect of the coefficient of friction of a running surface on an athlete's sprint time in a sled-towing exercise. The coefficients of friction of four common sports surfaces (a synthetic athletics track, a natural grass rugby pitch, a 3G football pitch, and an artificial grass hockey pitch) were determined from the force required to tow a weighted sled across the surface. Timing gates were then used to measure the 30-m sprint time for six rugby players when towing a sled of varied weight across the surfaces. There were substantial differences between the coefficients of friction for the four surfaces (micro = 0.21-0.58), and in the sled-towing exercise the athlete's 30-m sprint time increased linearly with increasing sled weight. The hockey pitch (which had the lowest coefficient of friction) produced a substantially lower rate of increase in 30-m sprint time, but there were no significant differences between the other surfaces. The results indicate that although an athlete's sprint time in a sled-towing exercise is affected by the coefficient offriction of the surface, the relationship relationship between the athlete's rate of increase in 30-m sprint time and the coefficient of friction is more complex than expected.

Baseline strength can influence the ability of salivary free testosterone to predict squat and sprinting performance.

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Crewther, Blair T; Cook, Christian J; Gaviglio, Chris M; Kilduff, Liam P; Drawer, Scott

2012-01-01

The objective of this study was to determine if salivary free testosterone can predict an athlete's performance during back squats and sprints over time and the influence baseline strength on this relationship. Ten weight-trained male athletes were divided into 2 groups based on their 1 repetition maximum (1RM) squats, good squatters (1RM > 2.0 × body weight, n = 5) and average squatters (1RM squat 1RM and 10-m sprint times on 10 separate occasions over a 40-day period. A saliva sample was collected before testing and assayed for free testosterone and cortisol. The pooled testosterone correlations were strong and significant in the good squatters (r = 0.92 for squats, r = -0.87 for sprints, p squats, r = -0.18 for sprints). Cortisol showed no significant correlations with 1RM squat and 10-m sprint performance, and no differences were identified between the 2 squatting groups. In summary, these results suggest that free testosterone is a strong individual predictor of squat and sprinting performance in individuals with relatively high strength levels but a poor predictor in less strong individuals. This information can assist coaches, trainers, and performance scientists working with stronger weight-trained athletes, for example, the preworkout measurement of free testosterone could indicate likely training outcomes or a readiness to train at a certain intensity level, especially if real-time measurements are made. Our results also highlight the need to separate group and individual hormonal data during the repeated testing of athletes with variable strength levels.

Improvement of Ice Hockey Players' On-Ice Sprint With Combined Plyometric and Strength Training.

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Dæhlin, Torstein E; Haugen, Ole C; Haugerud, Simen; Hollan, Ivana; Raastad, Truls; Rønnestad, Bent R

2017-08-01

Combined plyometric and strength training has previously been suggested as a strategy to improve skating performance in ice hockey players. However, the effects of combined plyometric and strength training have not previously been compared with the effects of strength training only. To compare the effects of combined plyometric and strength training on ice hockey players' skating sprint performance with those of strength training only. Eighteen participants were randomly assigned to 2 groups that completed 5 strength-training sessions/wk for 8 wk. One group included plyometric exercises at the start of 3 sessions/wk (PLY+ST), and the other group included core exercises in the same sessions (ST). Tests of 10- and 35-m skating sprints, horizontal jumping, 1-repetition-maximum (1 RM) squat, skating multistage aerobic test (SMAT), maximal oxygen consumption, repeated cycle sprints, and body composition were performed before and after the intervention. The participants increased their 1RM squat, lean mass, and body mass (P plyometric and strength training for 8 wk was superior to strength training alone at improving 10-m on-ice sprint performance in high-level ice hockey players.

Effects of a contrast training programme on jumping, sprinting and agility performance of prepubertal basketball players.

Science.gov (United States)

Latorre Román, Pedro Ángel; Villar Macias, Francisco Javier; García Pinillos, Felipe

2018-04-01

The purpose of this study was to examine the effects of a 10 week contrast training (CT) programme (isometric + plyometric) on jumping, sprinting abilities and agility performance in prepubertal basketball players. Fifty-eight children from a basketball academy (age: 8.72 ± 0.97 years; body mass index: 17.22 ± 2.48 kg/m 2 ) successfully completed the study. Participants were randomly assigned to experimental groups (EG, n = 30) and control groups (CG, n = 28). The CT programme was included in the experimental group's training sessions - twice a week - as part of their usual weekly training regime. This programme included 3 exercises: 1 isometric and 2 plyometric. Jumping, sprinting and agility performance were assessed before and after the training programme. Significant differences were found in posttest between EG and CG in sprint and T-test: EG showed better results than CG. Furthermore, there were significant differences in posttest-pretest between EG and CG in squat jump, countermovement jump, drop jump, sprint and T-test with the EG showing better results than CG. The CT programme led to increases in vertical jump, sprint and agility levels, so that the authors suggest that prepubertal children exhibit high muscular strength trainability.

Relationship Between Jumping Ability, Agility and Sprint Performance of Elite Young Basketball Players: A Field-Test Approach

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Abbas Asadi

2016-05-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p177   The purpose of this study was to determine the relationships between sprint, agility and jump performance of elite young basketball players. Sixteen elite national level young male basketball players participated in this study. The jumping ability of each player was determined using countermovement jump (CMJ, and broad long jump (BLJ. The agility T test (TT and Illinois agility test (IAT were assessed to determine the agility, and 20-m sprint time was also measured to determine sprint performance. The results of Pearson Product Moment Correlation analysis indicated moderate correlation between training age and IAT (r = -0.57; p = 0.021. Strong correlations were found between CMJ and BLJ (r = 0.71; p = 0.002, and between TT and IAT (r = 0.70; p = 0.002. Similarly, 20-m sprint time was strong correlated with CMJ (r = -0.61; p = 0.011, BLJ (r = -0.76; p = 0.001, TT (r = 0.77; p = 0.001, and IAT (r = 0.68; p = 0.003. In addition, CMJ was strongly correlated with TT (r = -0.60; p = 0.013, and IAT (r = -0.64; p = 0.007, and also strong correlation between BLJ with TT (r = -0.85; p = 0.001 and IAT (r = -0.76; p = 0.001. The findings of the present study indicated significant correlation between sprint and agility, jumping ability and sprint performance and between jumping ability and agility performance in basketball players. Therefore, the results suggest that sprint, agility and jumping ability share common physiological and biomechanical determinants.

Can a 15m-overground wheelchair sprint be used to assess wheelchair-specific anaerobic work capacity?

NARCIS (Netherlands)

van der Scheer, Jan W.; de Groot, Sonja; Vegter, Riemer J. K.; Veeger, DirkJan (H. E. J. ); van der Woude, Lucas H. V.

OBJECTIVE: To evaluate whether outcomes based on stopwatch time and power output (PO) over a 15m-overground wheelchair sprint test can be used to assess wheelchair-specific anaerobic work capacity, by studying their relationship with outcomes on a Wingate-based 30s-wheelchair ergometer sprint

Can a 15m-overground wheelchair sprint be used to assess wheelchair-specific anaerobic work capacity?

NARCIS (Netherlands)

van der Scheer, J.W.; De Groot, S.; Vegter, R.J.K.; Veeger, H.E.J.; van der Woude, L.H.V.

2014-01-01

Objective: To evaluate whether outcomes based on stopwatch time and power output (PO) over a 15. m-overground wheelchair sprint test can be used to assess wheelchair-specific anaerobic work capacity, by studying their relationship with outcomes on a Wingate-based 30. s-wheelchair ergometer sprint

EFFECT OF MUSCLE ENERGY TECHNIQUE ON FLEXIBILITY OF HAMSTRING AND CALF MUSCLES AND SPRINTING PERFORMANCE IN SPRINTERS

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M. Prasad Naik

2015-10-01

Full Text Available Background: Muscle energy technique is used for restoring normal tone in hypertonic muscles, strengthening weak muscles, preparing muscle for subsequent stretching, one of the main uses of this method is to normalize joint range which may help in increase flexibility and performance in sprinters. The aim of the study is to evaluate the effect of muscle energy technique on flexibility of hamstrings and calf muscles and sprinting performance in sprinters. The objective of the study is to determine the muscle energy technique on hamstrings and calf muscle flexibility and sprinting performance in sprinters by using goniometer and timing of sprinting performance. Method: The study design is an experimental study in which 30 male sprinters were recruited in this study. The study sample included all male healthy sprinters, aged between 15 -30 years. All subjects received warm up, muscle energy technique and cool down exercises daily for a period of 6weeks.The outcome measures are 90°-90°popliteal angle for assessing hamstring flexibility and ROM of ankle joint for calf muscles by universal goniometer and sprinting performance time by using stopwatch. Results: Independent t-test and paired t- test are used to analyse the data. A significant difference was found between pre and post values of hamstring and calf muscle flexibility and sprinting performance after the analysis in this study. Conclusion: This study shows that there was a significant effect of MET on hamstring and calf muscle flexibility and sprinting performance.

Mechanical power, thrust power and propelling efficiency: relationships with elite sprint swimming performance.

Science.gov (United States)

Gatta, Giorgio; Cortesi, Matteo; Swaine, Ian; Zamparo, Paola

2018-03-01

The purpose of this study was to explore the relationships between mechanical power, thrust power, propelling efficiency and sprint performance in elite swimmers. Mechanical power was measured in 12 elite sprint male swimmers: (1) in the laboratory, by using a whole-body swimming ergometer (W' TOT ) and (2) in the pool, by measuring full tethered swimming force (F T ) and maximal swimming velocity (V max ): W' T  = F T  · V max . Propelling efficiency (η P ) was estimated based on the "paddle wheel model" at V max . V max was 2.17 ± 0.06 m · s -1 , η P was 0.39 ± 0.02, W' T was 374 ± 62 W and W' TOT was 941 ± 92 W. V max was better related to W' T (useful power output: R = 0.943, P swimming performance. The ratio W' T /W' TOT (0.40 ± 0.04) represents the fraction of total mechanical power that can be utilised in water (e.g., η P ) and was indeed the same as that estimated based on the "paddle wheel model"; this supports the use of this model to estimate η P in swimming.

Reference equation for prediction of a total distance during six-minute walk test using Indonesian anthropometrics.

Science.gov (United States)

Nusdwinuringtyas, Nury; Widjajalaksmi; Yunus, Faisal; Alwi, Idrus

2014-04-01

to develop a reference equation for prediction of the total distance walk using Indonesian anthropometrics of sedentary healthy subjects. Subsequently, the prediction obtained was compared to those calculated by the Caucasian-based Enright prediction equation. the cross-sectional study was conducted among 123 healthy Indonesian adults with sedentary life style (58 male and 65 female subjects in an age range between 18 and 50 years). Heart rate was recorded using Polar with expectation in the sub-maximal zone (120-170 beats per minute). The subjects performed two six-minute walk tests, the first one on a 15-meter track according to the protocol developed by the investigator. The second walk was carried out on Biodex®gait trainer as gold standard. an average total distance of 547±54.24 m was found, not significantly different from the gold standard of 544.72±54.11 m (p>0.05). Multiple regression analysis was performed to develop the new equation. the reference equation for prediction of the total distance using Indonesian anthropometrics is more applicable in Indonesia.

Differences in activation properties of the hamstring muscles during overground sprinting.

Science.gov (United States)

Higashihara, Ayako; Nagano, Yasuharu; Ono, Takashi; Fukubayashi, Toru

2015-09-01

The purpose of this study was to quantify activation of the biceps femoris (BF) and medial hamstring (MH) during overground sprinting. Lower-extremity kinematics and electromyography (EMG) of the BF and MH were recorded in 13 male sprinters performing overground sprinting at maximum effort. Mean EMG activity was calculated in the early stance, late stance, mid-swing, and late-swing phases. Activation of the BF was significantly greater during the early stance phase than the late stance phase (p<0.01). Activation of the BF muscle was significantly lower during the first half of the mid-swing phase than the other phases (p<0.05). The MH had significantly greater EMG activation relative to its recorded maximum values compared to that for the BF during the late stance (p<0.05) and mid-swing (p<0.01) phases. These results indicate that the BF shows high activation before and after foot contact, while the MH shows high activation during the late stance and mid-swing phases. We concluded that the activation properties of the BF and MH muscles differ within the sprinting gait cycle. Copyright © 2015 Elsevier B.V. All rights reserved.

Data Sprints: A Collaborative Format in Digital Controversy Mapping

DEFF Research Database (Denmark)

Munk, Anders Kristian; Tommaso, Venturini; Meunier, Axel

2017-01-01

driven by a desire to provide navigational aids to actors faced with the challenge of making sense of complicated techno-scientific problems. Natively digital media technologies have thus been re-appropriated by STS researchers specifically for the purpose of mapping controversies in a way that would...... experiences with various forms of public engagement and participation. Through a concrete reappropriation of a collaborative format that is indeed native to the digital domain - namely the hackathon - we will show how digital methods can make a difference in participatory STS research. The data sprint, as we...... in amsterdam. Through a mix of digital methods ranging from web cartography and text mining to scientometrics and social media analysis we took on questions related to climate adaptation funding, vulnerability assessment, project management, and dynamics of the international negotiations. The sprints hardwired...

A comparison of assisted, resisted, and common plyometric training modes to enhance sprint and agility performance.

Science.gov (United States)

Khodaei, Kazem; Mohammadi, Abbas; Badri, Neda

2017-10-01

The purpose of this study was to compare the effect of assisted, resisted and common plyometric training modes to enhance sprint and agility performance. Thirty active young males (age 20.67±1.12, height 174.83±4.69, weight 63.45±7.51) volunteered to participate in this study that 24 completed testing. The participants were randomly assigned into different groups: assisted, resisted and common plyometric exercises groups. Plyometric training involved three sessions per week for 4 weeks. The volume load of plyometric training modes was equated between the groups. The posttest was performed after 48 hours of the last training session. Between-group differences were analyzed with the ANCOVA and LSD post-hoc tests, and within-group differences were analyzed by a paired t-test. The findings of the present study indicated that 0-10-m, 20-30-m sprint time and the Illinois Agility Test time significantly decreased in the assisted and resisted plyometrics modes compared to the common plyometric training mode (P≤0.05). Also, the 0-10-m, 0-30-m sprint time and agility T-test time was significantly reduced with resisted plyometrics modes compared to the assisted and common plyometric modes (P≤0.05). There was no significant difference in the 10-20-m sprint time among the three plyometric training modes. The results of this study demonstrated that assisted and resisted plyometrics modes with elastic bands were effective methods to improve sprint and agility performance than common plyometric training in active males. Also, the resisted plyometrics mode was superior than the assisted plyometrics mode to improving sprint and agility tasks.

Adipose tissue extracts plasma ammonia after sprint exercise in women and men

DEFF Research Database (Denmark)

Esbjörnsson, Mona; Bülow, Jens; Norman, Barbara

2006-01-01

This study evaluates a possible contribution of adipose tissue to the elimination of plasma ammonia (NH(3)) after high-intensity sprint exercise. In 14 healthy men and women, repeated blood samples for plasma NH(3) analyses were obtained from brachial artery and from a subcutaneous abdominal vein......) with glutamate resulting in its conversion to glutamine. Adipose tissue may thus play an important physiological role in eliminating plasma NH(3) and thereby reducing the risk of NH(3) intoxication after high-intensity exercise.......This study evaluates a possible contribution of adipose tissue to the elimination of plasma ammonia (NH(3)) after high-intensity sprint exercise. In 14 healthy men and women, repeated blood samples for plasma NH(3) analyses were obtained from brachial artery and from a subcutaneous abdominal vein...... before and after three repeated 30-s cycle sprints separated by 20 min of recovery. Biopsies from subcutaneous abdominal adipose tissue were obtained and analyzed for glutamine and glutamate content. After exercise, both arterial and abdominal venous plasma NH(3) concentrations were lower in women than...

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.

The combination of plyometric and balance training improves sprint and shuttle run performances more often than plyometric-only training with children.

Science.gov (United States)

Chaouachi, Anis; Othman, Aymen Ben; Hammami, Raouf; Drinkwater, Eric J; Behm, David G

2014-02-01

Because balance is not fully developed in children and studies have shown functional improvements with balance only training studies, a combination of plyometric and balance activities might enhance static balance, dynamic balance, and power. The objective of this study was to compare the effectiveness of plyometric only (PLYO) with balance and plyometric (COMBINED) training on balance and power measures in children. Before and after an 8-week training period, testing assessed lower-body strength (1 repetition maximum leg press), power (horizontal and vertical jumps, triple hop for distance, reactive strength, and leg stiffness), running speed (10-m and 30-m sprint), static and dynamic balance (Standing Stork Test and Star Excursion Balance Test), and agility (shuttle run). Subjects were randomly divided into 2 training groups (PLYO [n = 14] and COMBINED [n = 14]) and a control group (n = 12). Results based on magnitude-based inferences and precision of estimation indicated that the COMBINED training group was considered likely to be superior to the PLYO group in leg stiffness (d = 0.69, 91% likely), 10-m sprint (d = 0.57, 84% likely), and shuttle run (d = 0.52, 80% likely). The difference between the groups was unclear in 8 of the 11 dependent variables. COMBINED training enhanced activities such as 10-m sprints and shuttle runs to a greater degree. COMBINED training could be an important consideration for reducing the high velocity impacts of PLYO training. This reduction in stretch-shortening cycle stress on neuromuscular system with the replacement of balance and landing exercises might help to alleviate the overtraining effects of excessive repetitive high load activities.

Improvement of Repeated-Sprint Ability and Horizontal-Jumping Performance in Elite Young Basketball Players With Low-Volume Repeated-Maximal-Power Training.

Science.gov (United States)

Gonzalo-Skok, Oliver; Tous-Fajardo, Julio; Arjol-Serrano, José Luis; Suarez-Arrones, Luis; Casajús, José Antonio; Mendez-Villanueva, Alberto

2016-05-01

To examine the effects of a low-volume repeated-power-ability (RPA) training program on repeated-sprint and change-of- direction (COD) ability and functional jumping performance. Twenty-two male elite young basketball players (age 16.2 ± 1.2 y, height 190.0 ± 10.0 cm, body mass 82.9 ± 10.1 kg) were randomly assigned either to an RPA-training group (n = 11) or a control group (n = 11). RPA training consisted of leg-press exercise, twice a week for 6 wk, of 1 or 2 blocks of 5 sets × 5 repetitions with 20 s of passive recovery between sets and 3 min between blocks with the load that maximized power output. Before and after training, performance was assessed by a repeated-sprint-ability (RSA) test, a repeated-COD-ability test, a hop for distance, and a drop jump followed by tests of a double unilateral hop with the right and left legs. Within-group and between-groups differences showed substantial improvements in slowest (RSAs) and mean time (RSAm) on RSA; best, slowest and mean time on repeated-COD ability; and unilateral right and left hop in the RPA group in comparison with control. While best time on RSA showed no improvement in any group, there was a large relationship (r = .68, 90% CI .43;.84) between the relative decrement in RSAm and RSAs, suggesting better sprint maintenance with RPA training. The relative improvements in best and mean repeated-COD ability were very largely correlated (r = .89, 90% CI .77;.94). Six weeks of lowvolume (4-14 min/wk) RPA training improved several physical-fitness tests in basketball players.

Lateral Squats Significantly Decrease Sprint Time in Collegiate Baseball Athletes

Directory of Open Access Journals (Sweden)

Jason B. White

2016-03-01

Full Text Available The purpose was to examine the effect of prior performance of dumbbell lateral squats (DBLS on an agility movement-into-a-sprint (AMS test. Twelve collegiate, resistance-trained, baseball athletes participated in three sessions separated by three days. Session One consisted of AMS baseline test, DBLS 5-RM test, and experimental protocol familiarization. Subjects were randomly assigned the protocol order for Sessions Two and Three, which consisted of warm up followed by 1-min sitting (no-DBLS or performing the DBLS for 1 × 5 repetitions @ 5RM for each leg. Four minutes of slow recovery walking preceded the AMS test, which consisted of leading off a base and waiting for a visual stimulus. In reaction to stimulus, subjects exerted maximal effort while moving to the right by either pivoting or drop stepping and sprinting for 10 yards (yd. In Session Three, subjects switched protocols (DBLS, no-DBLS. Foot contact time (FCT, stride frequency (SF, stride length (SL, and 10-yd sprint time were measured. There were no differences between conditions for FCT, SF, or SL. Differences existed between DBLS (1.85 ± 0.09 s and no-DBLS (1.89 ± 0.10 s for AMS (p = 0.03. Results from the current study support the use of DBLS for performance enhancement prior to performing the AMS test.

When Is a Sprint a Sprint? A Review of the Analysis of Team-Sport Athlete Activity Profile

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Alice J. Sweeting

2017-06-01

Full Text Available The external load of a team-sport athlete can be measured by tracking technologies, including global positioning systems (GPS, local positioning systems (LPS, and vision-based systems. These technologies allow for the calculation of displacement, velocity and acceleration during a match or training session. The accurate quantification of these variables is critical so that meaningful changes in team-sport athlete external load can be detected. High-velocity running, including sprinting, may be important for specific team-sport match activities, including evading an opponent or creating a shot on goal. Maximal accelerations are energetically demanding and frequently occur from a low velocity during team-sport matches. Despite extensive research, conjecture exists regarding the thresholds by which to classify the high velocity and acceleration activity of a team-sport athlete. There is currently no consensus on the definition of a sprint or acceleration effort, even within a single sport. The aim of this narrative review was to examine the varying velocity and acceleration thresholds reported in athlete activity profiling. The purposes of this review were therefore to (1 identify the various thresholds used to classify high-velocity or -intensity running plus accelerations; (2 examine the impact of individualized thresholds on reported team-sport activity profile; (3 evaluate the use of thresholds for court-based team-sports and; (4 discuss potential areas for future research. The presentation of velocity thresholds as a single value, with equivocal qualitative descriptors, is confusing when data lies between two thresholds. In Australian football, sprint efforts have been defined as activity >4.00 or >4.17 m·s−1. Acceleration thresholds differ across the literature, with >1.11, 2.78, 3.00, and 4.00 m·s−2 utilized across a number of sports. It is difficult to compare literature on field-based sports due to inconsistencies in velocity and

The acute effects of heavy back and front squats on speed during forty-meter sprint trials.

Science.gov (United States)

Yetter, Mike; Moir, Gavin L

2008-01-01

The purpose of the present study was to investigate the effects of performing heavy back squats (HBS) and heavy front squats (HFS) on the average speed during each 10-m interval of 40-m sprint trials. In a randomized, cross-over design, 10 strength-trained men performed a HBS, HFS, or control treatment before performing three 40-m sprint trials separated by 3 minutes. The HBS and HFS treatments consisted of performing parallel back or front squats with 30%, 50%, and 70% of the subject's 1 repetition maximum after 5 minutes of cycling. The control treatment consisted of cycling for 5 minutes. The sprint trials were performed 4 minutes after completing the HBS, HFS, or control treatments. Significant increases in speed were found during the 10- to 20-m interval for the HBS compared with the control treatment (mean difference, 0.12 m x s(-1); 95% likely range, 0.05-0.18 m x s(-1); P = 0.001). During the 30- to 40-m interval, HBS produced significantly greater speeds compared with the HFS treatment (mean difference, 0.24 m x s(-1); 95% likely range, 0.02-0.45 m x s(-1); P = 0.034) and the control treatment (mean difference, 0.18 m x s(-1); 95% likely range, 0.03-0.32 m x s(-1); P = 0.021). The differing effects of the treatments may reflect different levels of muscular activation or different mechanical aspects of the squat exercises. Similarly, the multidimensional nature of sprint running means that other specific exercises may confer improvements in sprinting performance during other intervals. It is suggested that coaches could incorporate HBS into the warm-up procedure of athletes to improve sprinting performance.

Neck-cooling improves repeated sprint performance in the heat

Directory of Open Access Journals (Sweden)

Caroline eSunderland

2015-11-01

Full Text Available The present study evaluated the effect of neck-cooling during exercise on repeated sprint ability in a hot environment. Seven team-sport playing males completed two experimental trials involving repeated sprint exercise (5 x 6 s before and after two 45 min bouts of a football specific intermittent treadmill protocol in the heat (33.0  0.2 ºC; 53 ± 2% relative humidity. Participants wore a neck-cooling collar in one of the trials (CC. Mean power output and peak power output declined over time in both trials but were higher in CC (540 ± 99 v 507 ± 122W, d = 0.32; 719 ± 158 v 680 ± 182 W, d = 0.24 respectively. The improved power output was particularly pronounced (d = 0.51 – 0.88 after the 2nd 45 min bout but the CC had no effect on % fatigue. The collar lowered neck temperature and the thermal sensation of the neck (P 0.05. There were no trial differences but interaction effects were demonstrated for prolactin concentration and rating of perceived exertion (RPE. Prolactin concentration was initially higher in the collar cold trial and then was lower from 45 minutes onwards (interaction trial x time P=0.04. RPE was lower during the football intermittent treadmill protocol in the collar cold trial (interaction trial x time P = 0.01. Neck-cooling during exercise improves repeated sprint performance in a hot environment without altering physiological or neuroendocrinological responses. RPE is reduced and may partially explain the performance improvement.

Kinematic analysis of competitive sprinting | Ansari | African Journal ...

African Journals Online (AJOL)

The results of the study showed that the kinematic variables i.e. knee angle, hip angle, ankle angle, shoulder rotation and extension had a significant influence on sprinting style. The results indicated that the kinematic variables of running style, knee angle at landing, hip flexion, ankle angle at landing, ankle angle at take-off, ...

Supervisory Presentation for Research, Information, Integration and Testing (SPRINT)

Science.gov (United States)

2015-03-29

in Microsoft Visual Studio and several third party developer libraries (See Figure 4). All distributed laboratory sites have similar hardware...Testing (SPRINT). 15. SUBJECT TERMS Supervisory Control, Multi-Modal Interfaces, Scalable Interfaces, Advanced Visualization , Augmented Symbology 16...23 Figure 9. Fusion Visual Framework Components

Sprint performance and propulsion asymmetries on an ergometer in trained high- and low-point wheelchair rugby players

NARCIS (Netherlands)

Goosey-Tolfrey, Victoria L; Vegter, Riemer J K; Mason, Barry S; Paulson, Thomas A W; Lenton, John P; van der Scheer, Jan W; van der Woude, Lucas H V

The purpose of this study was to examine the propulsion asymmetries of wheelchair athletes while sprinting on an instrumented, dual-roller ergometer system. Eighteen experienced wheelchair rugby players (8 low point (LP) (class 1.5) and 10 high point (HP) (class 2.0)) performed a 15-second sprint in

Acute Effects of Plyometric Intervention—Performance Improvement and Related Changes in Sprinting Gait Variability.

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Maćkała, Krzysztof; Fostiak, Marek

2015-07-01

The purpose of this study was to examine the effect of a short high-intensity plyometric program on the improvement of explosive power of lower extremities and sprint performance as well as changes in sprinting stride variability in male sprinters. Fourteen healthy male sprinters (mean ± SD: age: 18.07 ± 0.73 years, body mass: 73 ± 9.14 kg, height: 180.57 ± 8.16 cm, and best 100 m: 10.89 ± 0.23) participated in the experiment. The experimental protocol included vertical jumping such as squat jump, countermovement jump, and horizontal jumps; standing long jump and standing triple jumps to assess lower-body power, maximal running velocity; a 20-m flying start sprint that evaluated variability of 10 running steps and 60-m starting block sprint. All analyzed parameters were obtained using the new technology of OptoJump-Microgate (OptoJump, Italy). The short-term plyometric training program significantly increased the explosive power of lower extremities, both vertical and horizontal jumping improvement. However, the vertical jumps increased much more than the horizontal. The 20-m improvements were derived from an increase of stride frequency from 4.31 to 4.39 Hz because of a decrease of ground contact time from 138 to 133 milliseconds. This did not translate into step length changes. Therefore, the significantly increased frequency of stride (1.8%), which is a specific expression of ground contact time reduction during support phase, resulted in an increase of speed. The training volume of 2 weeks (with 6 sessions) using high-intensity (between 180 and 250 jumps per session) plyometric exercises can be recommended as the short-term strategy that will optimize one's probability of reaching strong improvements in explosive power and sprint velocity performance.

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

REPEATED SPRINT ABILITY AND RECOVERY PERIOD: COMPARISON OF TRAINED AND UNTRAINED INDIVIDUALS

OpenAIRE

Sultan

2016-01-01

The purpose of the study was to investigate the effects of training both in repeated sprint ability (RSA) and during the recovery after sprint. Soccer players playing in regional amateur league (n=14, age: 21.86±2.35 years, height: 180.14±4.54 cm, body mass: 72.57±5.03 kg, training age: 8.71±1.86 years) and students from faculty of sport sciences that played soccer in the past (n=13, age: 23.77±2.65 years, height: 178.54±4.67 cm, body mass: 74.54±10.52 kg) participated in this study as traine...

Paralympic Sprint Performance Between 1992 and 2012.

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Grobler, Lara; Ferreira, Suzanne; Terblanche, Elmarie

2015-11-01

The Paralympic Games have undergone many changes since their inception in 1960, one being the advances made in running-specific prostheses (RSPs) for track athletes with lower-limb amputations. To investigate the sprinting-performance changes in athletes with lower-limb amputations since 1992 to assess whether the influence of developments in RSP technology is evident. The results of the Olympic and Paralympic Games ranging between 1992 and 2012 for the 100-m and 200-m were collected, and performance trends, percentage change in performance, and competition density (CD) were calculated. The results indicate that the greatest performance increases were seen in athletes with lower-limb amputations (T42 = 26%, T44 = 14%). These performance improvements were greater than for Olympic athletes (Paralympic athletes from other selected classes (Paralympic sprint performances, RSP technology has played a noteworthy role in the progression of performances of athletes with amputations. It is also hypothesized that the difference in the performance improvements between the T42 and T44 classes is due to the level of disability and therefore the extent to which technology is required to enable locomotion. It is evident that RSP technology has played a significant role in the progression of performances in athletes with lower-limb amputations.

Lower limb joint kinetics and ankle joint stiffness in the sprint start push-off.

Science.gov (United States)

Charalambous, Laura; Irwin, Gareth; Bezodis, Ian N; Kerwin, David

2012-01-01

Sprint push-off technique is fundamental to sprint performance and joint stiffness has been identified as a performance-related variable during dynamic movements. However, joint stiffness for the push-off and its relationship with performance (times and velocities) has not been reported. The aim of this study was to quantify and explain lower limb net joint moments and mechanical powers, and ankle stiffness during the first stance phase of the push-off. One elite sprinter performed 10 maximal sprint starts. An automatic motion analysis system (CODA, 200 Hz) with synchronized force plates (Kistler, 1000 Hz) collected kinematic profiles at the hip, knee, and ankle and ground reaction forces, providing input for inverse dynamics analyses. The lower-limb joints predominately extended and revealed a proximal-to-distal sequential pattern of maximal extensor angular velocity and positive power production. Pearson correlations revealed relationships (P push-off in different ways, depending on the phase of stance considered.

Match-to-match variation in physical activity and technical skill measures in professional Australian Football.

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Kempton, Thomas; Sullivan, Courtney; Bilsborough, Johann C; Cordy, Justin; Coutts, Aaron J

2015-01-01

To determine the match-to-match variability in physical activity and technical performance measures in Australian Football, and examine the influence of playing position, time of season, and different seasons on these measures of variability. Longitudinal observational study. Global positioning system, accelerometer and technical performance measures (total kicks, handballs, possessions and Champion Data rank) were collected from 33 players competing in the Australian Football League over 31 matches during 2011-2012 (N=511 observations). The global positioning system data were categorised into total distance, mean speed (mmin(-1)), high-speed running (>14.4 kmh(-1)), very high-speed running (>19.9 kmh(-1)), and sprint (>23.0 kmh(-1)) distance while player load was collected from the accelerometer. The data were log transformed to provide coefficient of variation and the between subject standard deviation (expressed as percentages). Match-to-match variability was increased for higher speed activities (high-speed running, very high-speed running, sprint distance, coefficient of variation %: 13.3-28.6%) compared to global measures (speed, total distance, player load, coefficient of variation %: 5.3-9.2%). The between-match variability was relativity stable for all measures between and within AFL seasons, with only few differences between positions. Higher speed activities (high-speed running, very high-speed running, sprint distance), but excluding mean speed, total distance and player load, were all higher in the final third phase of the season compared to the start of the season. While global measures of physical performance are relatively stable, higher-speed activities and technical measures exhibit a large degree of between-match variability in Australian Football. However, these measures remain relatively stable between positions, and within and between Australian Football League seasons. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd

Isometric Mid-Thigh Pull Correlates With Strength, Sprint, and Agility Performance in Collegiate Rugby Union Players.

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Wang, Ran; Hoffman, Jay R; Tanigawa, Satoru; Miramonti, Amelia A; La Monica, Michael B; Beyer, Kyle S; Church, David D; Fukuda, David H; Stout, Jeffrey R

2016-11-01

Wang, R, Hoffman, JR, Tanigawa, S, Miramonti, AA, La Monica, MB, Beyer, KS, Church, DD, Fukuda, DH, and Stout, JR. Isometric mid-thigh pull correlates with strength, sprint, and agility performance in collegiate rugby union players. J Strength Cond Res 30(11): 3051-3056, 2016-The purpose of this investigation was to examine the relationships between isometric mid-thigh pull (IMTP) force and strength, sprint, and agility performance in collegiate rugby union players. Fifteen members of a champion-level university's club rugby union team (mean ± SD: 20.67 ± 1.23 years, 1.78 ± 0.06 m, and 86.51 ± 14.18 kg) participated in this investigation. One repetition maximum (1RM) squat, IMTP, speed (40 m sprint), and agility (proagility test and T-test) were performed during 3 separate testing sessions. Rate of force development (RFD) and force output at 30, 50, 90, 100, 150, 200, and 250 milliseconds of IMTP, as well as the peak value were determined. Pearson product-moment correlation analysis was used to examine the relationships between these measures. Performance in the 1RM squat was significantly correlated to the RFD between 90 and 250 milliseconds from the start of contraction (r's ranging from 0.595 to 0.748), and peak force (r = 0.866, p ≤ 0.05). One repetition maximum squat was also correlated to force outputs between 90 and 250 milliseconds (r's ranging from 0.757 to 0.816, p ≤ 0.05). Sprint time over the first 5 m in the 40 m sprint was significantly (p ≤ 0.05) correlated with peak RFD (r = -0.539) and RFD between 30 and 50 milliseconds (r's = -0.570 and -0.527, respectively). Time for the proagility test was correlated with peak RFD (r = -0.523, p ≤ 0.05) and RFD between 30 and 100 milliseconds (r's ranging from -0.518 to -0.528, p's strength, agility, and sprint performance. Future studies should examine IMTP as a potential tool to monitor athletic performance during the daily training of rugby union players.

Cognitive Function and Kidney Disease: Baseline Data From the Systolic Blood Pressure Intervention Trial (SPRINT).

Science.gov (United States)

Weiner, Daniel E; Gaussoin, Sarah A; Nord, John; Auchus, Alexander P; Chelune, Gordon J; Chonchol, Michel; Coker, Laura; Haley, William E; Killeen, Anthony A; Kimmel, Paul L; Lerner, Alan J; Oparil, Suzanne; Saklayen, Mohammad G; Slinin, Yelena M; Wright, Clinton B; Williamson, Jeff D; Kurella Tamura, Manjula

2017-09-01

Chronic kidney disease is common and is associated with cardiovascular disease, cerebrovascular disease, and cognitive function, although the nature of this relationship remains uncertain. Cross-sectional cohort using baseline data from the Systolic Blood Pressure Intervention Trial (SPRINT). Participants in SPRINT, a randomized clinical trial of blood pressure targets in older community-dwelling adults with cardiovascular disease, chronic kidney disease, or high cardiovascular disease risk and without diabetes or known stroke, who underwent detailed neurocognitive testing in the cognition substudy, SPRINT-Memory and Cognition in Decreased Hypertension (SPRINT-MIND). Urine albumin-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR). Cognitive function, a priori defined as 5 cognitive domains based on 11 cognitive tests using z scores, and abnormal white matter volume quantified by brain magnetic resonance imaging. Of 9,361 SPRINT participants, 2,800 participated in SPRINT-MIND and 2,707 had complete data; 637 had brain imaging. Mean age was 68 years, 37% were women, 30% were black, and 20% had known cardiovascular disease. Mean eGFR was 70.8±20.9mL/min/1.73m 2 and median urine ACR was 9.7 (IQR, 5.7-22.5) mg/g. In adjusted analyses, higher ACR was associated with worse global cognitive function, executive function, memory, and attention, such that each doubling of urine ACR had the same association with cognitive performance as being 7, 10, 6, and 14 months older, respectively. Lower eGFR was independently associated with worse global cognitive function and memory. In adjusted models, higher ACR, but not eGFR, was associated with larger abnormal white matter volume. Cross-sectional only, no patients with diabetes were included. In older adults, higher urine ACR and lower eGFR have independent associations with global cognitive performance with different affected domains. Albuminuria concurrently identifies a higher burden of abnormal brain

Effect of sprint training on resting serum irisin concentration - Sprint training once daily vs. twice every other day.

Science.gov (United States)

Tsuchiya, Yoshifumi; Ijichi, Toshiaki; Goto, Kazushige

2016-04-01

Exercise twice every other day has been shown to lead to increasing peroxisome proliferator receptor γ coactivator-1α (PGC-1α) expression (up-stream factor of irisin) via lowered muscle glycogen level during second of exercise compared with exercise once daily. This study determined the influence of 4weeks of sprint training (training once daily vs. twice every other day) on the serum irisin concentration. Twenty healthy males (20.9±1.3years) were assigned randomly to either the SINGLE or REPEATED group (n=10 per group). The subjects in the SINGLE group participated in a sprint training session once daily (5days per week), whereas those in the REPEATED group performed two consecutive training sessions on the same day with a 1-h rest between sessions (2-3days per week). Both groups completed 20 training sessions over 4weeks. Each training session consisted of three consecutive 30-s maximal pedaling exercises with a 10-min rest between sets. Blood samples were collected before and after training period (48h after completing the last training session). The serum irisin concentration decreased significantly after training in each group (SINGLE, 338.5±77.8 to 207.6±64.6ng/mL; REPEATED, 329.5±83.9 to 234.2±72.8ng/mL, pevery other day). Copyright © 2016 Elsevier Inc. All rights reserved.

Higher Drop in Speed during a Repeated Sprint Test in Soccer Players Reporting Former Hamstring Strain Injury

Science.gov (United States)

Røksund, Ola D.; Kristoffersen, Morten; Bogen, Bård E.; Wisnes, Alexander; Engeseth, Merete S.; Nilsen, Ann-Kristin; Iversen, Vegard V.; Mæland, Silje; Gundersen, Hilde

2017-01-01

Aim: Hamstring strain injury is common in soccer. The aim of this study was to evaluate the physical capacity of players who have and have not suffered from hamstring strain injury in a sample of semi-professional and professional Norwegian soccer players in order to evaluate characteristics and to identify possible indications of insufficient rehabilitation. Method: Seventy-five semi-professional and professional soccer players (19 ± 3 years) playing at the second and third level in the Norwegian league participated in the study. All players answered a questionnaire, including one question about hamstring strain injury (yes/no) during the previous 2 years. They also performed a 40 m maximal sprint test, a repeated sprint test (8 × 20 m), a countermovement jump, a maximal oxygen consumption (VO2max) test, strength tests and flexibility tests. Independent sample t-tests were used to evaluate differences in the physical capacity of the players who had suffered from hamstring strain injury and those who had not. Mixed between-within subject's analyses of variance was used to compare changes in speed during the repeated sprint test between groups. Results: Players who reported hamstring strain injury during the previous two years (16%) had a significantly higher drop in speed (0.07 vs. 0.02 s, p = 0.007) during the repeated sprint test, compared to players reporting no previous hamstring strain injury. In addition, there was a significant interaction (groups × time) (F = 3.22, p = 0.002), showing that speed in the two groups changed differently during the repeated sprint test. There were no significant differences in relations to age, weight, height, body fat, linear speed, countermovement jump height, leg strength, VO2max, or hamstring flexibility between the groups. Conclusion: Soccer players who reported hamstring strain injury during the previous 2 years showed significant higher drop in speed during the repeated sprint test compared to players with no hamstring

Repeated sprint ability and stride kinematics are altered following an official match in national-level basketball players.

Science.gov (United States)

Delextrat, A; Baliqi, F; Clarke, N

2013-04-01

The aim of the study was to investigate the effects of playing an official national-level basketball match on repeated sprint ability (RSA) and stride kinematics. Nine male starting basketball players (22.8±2.2 years old, 191.3±5.8 cm, 88±10.3 kg, 12.3±4.6% body fat) volunteered to take part. Six repetitions of maximal 4-s sprints were performed on a non-motorised treadmill, separated by 21-s of passive recovery, before and immediately after playing an official match. Fluid loss, playing time, and the frequencies of the main match activities were recorded. The peak, mean, and performance decrement for average and maximal speed, acceleration, power, vertical and horizontal forces, and stride parameters were calculated over the six sprints. Differences between pre- and post-match were assessed by student t-tests. Significant differences between pre- and post-tests were observed in mean speed (-3.3%), peak and mean horizontal forces (-4.3% and -17.4%), peak and mean vertical forces (-3.4% and -3.7%), contact time (+7.3%), stride duration (+4.6%) and stride frequency (-4.0%), (Pvertical force were significantly correlated to fluid loss and sprint, jump and shuffle frequencies (P<0.05). These results highlight that the impairment in repeated sprint ability depends on the specific activities performed, and that replacing fluid loss through sweating during a match is crucial.

Energy system contributions and determinants of performance in sprint cross-country skiing

DEFF Research Database (Denmark)

Andersson, E; Björklund, G; Holmberg, H-C

2017-01-01

To improve current understanding of energy contributions and determinants of sprint-skiing performance, 11 well-trained male cross-country skiers were tested in the laboratory for VO2max , submaximal gross efficiency (GE), maximal roller skiing velocity, and sprint time-trial (STT) performance...... during the STT was predicted from the submaximal relationships for GE against velocity and incline, allowing computation of metabolic rate and O2 deficit. The skiers completed the STT in 232 ± 10 s (distributed as 55 ± 3% DP and 45 ± 3% DS) with a mean power output of 324 ± 26 W. The anaerobic energy......-skiing has demonstrated an anaerobic energy contribution of 18%, with GE being the strongest predictor of performance....

Sex Comparison of Knee Extensor Size, Strength and Fatigue Adaptation to Sprint Interval Training.

Science.gov (United States)

Bagley, Liam; Al-Shanti, Nasser; Bradburn, Steven; Baig, Osamah; Slevin, Mark; McPhee, Jamie S

2018-03-12

Regular sprint interval training (SIT) improves whole-body aerobic capacity and muscle oxidative potential, but very little is known about knee extensor anabolic or fatigue resistance adaptations, or whether effects are similar for males and females. The purpose of this study was to compare sex-related differences in knee extensor size, torque-velocity relationship and fatigability adaptations to 12 weeks SIT. Sixteen males and fifteen females (mean (SEM) age: 41 (±2.5) yrs) completed measurements of total body composition assessed by DXA, quadriceps muscle cross-sectional area (CSAQ) assessed by MRI, the knee extensor torque-velocity relationship (covering 0 - 240°·sec) and fatigue resistance, which was measured as the decline in torque from the first to the last of 60 repeated concentric knee extensions performed at 180°·sec. SIT consisted of 4 x 20 second sprints on a cycle ergometer set at an initial power output of 175% of power at VO2max, three times per week for 12 weeks. CSAQ increased by 5% (p=0.023) and fatigue resistance improved 4.8% (p=0.048), with no sex differences in these adaptations (sex comparisons: p=0.140 and p=0.282, respectively). Knee extensor isometric and concentric torque was unaffected by SIT in both males and females (p>0.05 for all velocities). 12 weeks SIT, totalling 4 minutes very intense cycling per week, significantly increased fatigue resistance and CSAQ similarly in males and females, but did not significantly increase torque in males or females. These results suggest that SIT is a time-effective training modality for males and females to increase leg muscle size and fatigue resistance.

Development of repeated sprint ability in talented youth basketball players.

Science.gov (United States)

te Wierike, Sanne C M; de Jong, Mark C; Tromp, Eveline J Y; Vuijk, Pieter J; Lemmink, Koen A P M; Malina, Robert M; Elferink-Gemser, Marije T; Visscher, Chris

2014-04-01

Factors affecting repeated sprint ability (RSA) were evaluated in a mixed-longitudinal sample of 48 elite basketball players 14-19 years of age (16.1 ± 1.7 years). Players were observed on 6 occasions during the 2008-09 and 2009-10 seasons. Three following basketball-specific field tests were administered on each occasion: the shuttle sprint test for RSA, the vertical jump for lower body explosive strength (power), and the interval shuttle run test for interval endurance capacity. Height and weight were measured; body composition was estimated (percent fat, lean body mass). Multilevel modeling of RSA development curve was used with 32 players (16.0 ± 1.7 years) who had 2 or more observations. The 16 players (16.1 ± 1.8 years) measured on only 1 occasion were used as a control group to evaluate the appropriateness of the model. Age, lower body explosive strength, and interval endurance capacity significantly contributed to RSA (p ≤ 0.05). Repeated sprint ability improved with age from 14 to 17 years (p ≤ 0.05) and reached a plateau at 17-19 years. Predicted RSA did not significantly differ from measured RSA in the control group (p ≥ 0.05). The results suggest a potentially important role for the training of lower body explosive strength and interval endurance capacity in the development of RSA among youth basketball players. Age-specific reference values for RSA of youth players may assist basketball coaches in setting appropriate goals for individual players.

ENERGY EXPENDITURE AND HABITUAL PHYSICAL ACTIVITIES IN ADOLESCENT SPRINT ATHLETES

Directory of Open Access Journals (Sweden)

Dirk Aerenhouts

2011-06-01

Full Text Available This study aimed to assess total energy expenditure (TEE and specific habitual physical activities in adolescent sprint athletes. Two methods used to estimate TEE, an activity diary (AD and SenseWear armband (SWA, were compared. Sixteen athletes (6 girls, 10 boys, mean age 16.5 ± 1.6 yr simultaneously wore a SWA and completed an AD and food diary during one week. Basal energy expenditure as given by the SWA when taken off was corrected for the appropriate MET value using the AD. TEE as estimated by the AD and SWA was comparable (3196 ± 590 kcal and 3012 ± 518 kcal, p = 0.113 without day-to-day variations in TEE and energy expended in activities of high intensity. Daily energy intake (2569 ± 508 kcal did not match TEE according to both the AD and SWA (respectively p < 0.001 and p = 0.007. Athletes were in a supine position for a longer time on weekend days than on week days and slept longer on Sundays. Athletes reported a longer time of high-intensive physical activities in the AD than registered by the SWA on 4 out of 7 days. In addition to specific sprint activities on 3 to 7 days per week, 11 out of 16 athletes actively commuted to school where they participated in sports once or twice per week. The AD and the SWA are comparable in the estimation of TEE, which appears realistic and sustainable. The SWA offers an appropriate and objective method in the assessment of TEE, sleeping and resting in adolescent athletes on the condition that detailed information is given for the times the armband is not worn. The AD offers activity specific information but relies on the motivation, compliance and subjectivity of the individual, especially considering high-intensive intermittent training

Autonomic modulations of heart rate variability are associated with sports injury incidence in sprint swimmers.

Science.gov (United States)

Lima-Borges, Dayanne S; Martinez, Paula F; Vanderlei, Luiz Carlos M; Barbosa, Fernando S S; Oliveira-Junior, Silvio A

2018-03-28

Young athletes' participation in competitive sports is becoming increasingly common, and this increased involvement raises concerns about the occurrence of overtraining and sports injuries. Since these issues are poorly understood, this study analyzed heart rate variability, stress/recovery relationship, and sports injury incidence during a training macrocycle of young sprint and endurance swimmers. Thirty teenage swimmers (aged 12 to 17 years) were divided into two groups as follows: Sprint (n = 17) and Endurance (n = 13). Subjects were evaluated over 20 weeks, based on the following three schedules: general, specific, and competitive. In addition to heart rate variability and sports injury incidence, the Recovery-Stress-Questionnaire of Athletes was used to analyse stress/recovery states in athletes. All procedures were developed at the initial moment and at the end of each periodization step. The Sprint group presented a reduced standard deviation of normal-normal beats (73.0 ± 6.6 vs. 54.1 ± 3.5 ms; p sports injury than the Endurance group (0.0214 ± 0.0068 vs. 0.0136 ± 0.0050 cases/1000 hours). Sprint training was associated with progressive activation of the sympathetic nervous system as well as a higher incidence of sports injury in comparison to endurance swimming during a training macrocycle.

The locomotor activity of soccer players based on playing positions during the 2010 World Cup.

Science.gov (United States)

Soroka, Andrzej

2018-06-01

The aim of this study was to define the locomotor activity of footballer players during the 2010 World Cup and to assess what differences existed among different playing positions. Research was conducted using research material collected from the Castrol Performance Index, a kinematic game analysis system that records player movements during a game by use of semi-automatic cameras. A total of 599 players who participated in the championships were analyzed. The results were evaluated using one-way analysis of variance (ANOVA) and a post-hoc test that calculated the Honestly Significant Difference (HSD) in order to determine which mean values significantly differed among the player positions. It was found that midfielders covered on average the largest distance during a match (10,777.6 m, Plocomotor activity at high and sprint intensities (2936.8 m and 108.4 m, respectively). Additionally, midfielders also spent the largest amount of time at performing at a high intensity (10.6%). Strikers also featured high levels of the above parameters; the total length of distance covered with high intensities was found to be on average 2586.7 m, the distance covered at sprint intensity was 105 m. The footballers, playing at the championship level feature excellent locomotor preparation. This fact is undoubtedly supported by the aerobic training of high intensity. Such training allows footballers to extend the distance they cover during the match, increase the intensity of locomotor activities and sprint speed distance.

Skeletal Muscle Pyruvate Dehydrogenase Phosphorylation and Lactate Accumulation During Sprint Exercise in Normoxia and Severe Acute Hypoxia: Effects of Antioxidants

Directory of Open Access Journals (Sweden)

David Morales-Alamo

2018-03-01

Full Text Available Compared to normoxia, during sprint exercise in severe acute hypoxia the glycolytic rate is increased leading to greater lactate accumulation, acidification, and oxidative stress. To determine the role played by pyruvate dehydrogenase (PDH activation and reactive nitrogen and oxygen species (RNOS in muscle lactate accumulation, nine volunteers performed a single 30-s sprint (Wingate test on four occasions: two after the ingestion of placebo and another two following the intake of antioxidants, while breathing either hypoxic gas (PIO2 = 75 mmHg or room air (PIO2 = 143 mmHg. Vastus lateralis muscle biopsies were obtained before, immediately after, 30 and 120 min post-sprint. Antioxidants reduced the glycolytic rate without altering performance or VO2. Immediately after the sprints, Ser293- and Ser300-PDH-E1α phosphorylations were reduced to similar levels in all conditions (~66 and 91%, respectively. However, 30 min into recovery Ser293-PDH-E1α phosphorylation reached pre-exercise values while Ser300-PDH-E1α was still reduced by 44%. Thirty minutes after the sprint Ser293-PDH-E1α phosphorylation was greater with antioxidants, resulting in 74% higher muscle lactate concentration. Changes in Ser293 and Ser300-PDH-E1α phosphorylation from pre to immediately after the sprints were linearly related after placebo (r = 0.74, P < 0.001; n = 18, but not after antioxidants ingestion (r = 0.35, P = 0.15. In summary, lactate accumulation during sprint exercise in severe acute hypoxia is not caused by a reduced activation of the PDH. The ingestion of antioxidants is associated with increased PDH re-phosphorylation and slower elimination of muscle lactate during the recovery period. Ser293 re-phosphorylates at a faster rate than Ser300-PDH-E1α during the recovery period, suggesting slightly different regulatory mechanisms.

Acute effect of a complex training protocol of back squats on 30-m sprint times of elite male military athletes.

Science.gov (United States)

Ojeda, Álvaro Huerta; Ríos, Luis Chirosa; Barrilao, Rafael Guisado; Serrano, Pablo Cáceres

2016-03-01

[Purpose] The aim of this study was to determine the acute effect temporal of a complex training protocol on 30 meter sprint times. A secondary objective was to evaluate the fatigue indexes of military athletes. [Subjects and Methods] Seven military athletes were the subjects of this study. The variables measured were times in 30-meter sprint, and average power and peak power of squats. The intervention session with complex training consisted of 4 sets of 5 repetitions at 30% 1RM + 4 repetitions at 60% 1RM + 3 repetitions of 30 meters with 120-second rests. For the statistical analysis repeated measures of ANOVA was used, and for the post hoc analysis, student's t-test was used. [Results] Times in 30 meter sprints showed a significant reduction between the control set and the four experimental sets, but the average power and peak power of squats did not show significant changes. [Conclusion] The results of the study show the acute positive effect of complex training, over time, in 30-meter sprint by military athletes. This effect is due to the post activation potentiation of the lower limbs' muscles in the 30 meters sprint.

Características y efectos de los métodos resistidos en el sprint

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Pedro E. Alcaraz

2009-01-01

Full Text Available Para la mejora del rendimiento en el sprint se utilizan distintos métodos de entrenamiento, entre los más populares se encuentran los métodos resistidos. Un método resistido para el sprint se caracteriza por utilizar sprints con una sobrecarga o resistencia añadida. Dependiendo de las características del dispositivo, tanto la magnitud como la dirección de la resistencia va a ser diferente. Así, existen distintos tipos de métodos resistidos, estos son: arrastres de trineos o ruedas, lastres de chalecos o cinturones, arrastres de paracaídas, carreras cuesta arriba, e incluso carreras sobre la arena de la playa. El principal objetivo al usar métodos resistidos es mejorar la fuerza específica de los deportistas sin producir una modificación significativa de la técnica del deportista. En el presente trabajo se revisan las características y efectos de los métodos resistidos tanto de forma aguda, como sus efectos a corto, medio y largo plazo.

Repeated high-speed activities during youth soccer games in relation to changes in maximal sprinting and aerobic speeds.

Science.gov (United States)

Buchheit, M; Simpson, B M; Mendez-Villanueva, A

2013-01-01

The aim of this study was to examine in highly-trained young soccer players whether substantial changes in either maximal sprinting speed (MSS) or maximal aerobic speed (as inferred from peak incremental test speed, V(Vam-Eval)) can affect repeated high-intensity running during games. Data from 33 players (14.5±1.3 years), who presented substantial changes in either MSS or V(Vam-Eval) throughout 2 consecutive testing periods (~3 months) were included in the final analysis. For each player, time-motion analyses were performed using a global positioning system (1-Hz) during 2-10 international club games played within 1-2 months from/to each testing period of interest (n for game analyzed=109, player-games=393, games per player per period=4±2). Sprint activities were defined as at least a 1-s run at intensities higher than 61% of individual MSS. Repeated-sprint sequences (RSS) were defined as a minimum of 2 consecutive sprints interspersed with a maximum of 60 s of recovery. Improvements in both MSS and V(Vam-Eval) were likely associated with a decreased RSS occurrence, but in some positions only (e. g., - 24% vs. - 3% for improvements in MSS in strikers vs. midfielders, respectively). The changes in the number of sprints per RSS were less clear but also position-dependent, e. g., +7 to +12% for full-backs and wingers, - 5 to - 7% for centre-backs and midfielders. In developing soccer players, changes in repeated-sprint activity during games do not necessarily match those in physical fitness. Game tactical and strategic requirements are likely to modulate on-field players' activity patterns independently (at least partially) of players' physical capacities. © Georg Thieme Verlag KG Stuttgart · New York.

Acute and Post-Exercise Physiological Responses to High-Intensity Interval Training in Endurance and Sprint Athletes

OpenAIRE

Cipryan, Lukas; Tschakert, Gerhard; Hofmann, Peter

2017-01-01

The purpose of the presented study was to compare acute and post-exercise differences in cardiorespiratory, metabolic, cardiac autonomic, inflammatory and muscle damage responses to high-intensity interval exercise (HIIT) between endurance and sprint athletes. The study group consisted of sixteen highly-trained males (age 22.1 �� 2.5 years) participating in endurance (n = 8) or sprint (n = 8) sporting events. All the participants underwent three exercise sessions: short HIIT (work interval du...

Acute and Post-Exercise Physiological Responses to High-Intensity Interval Training in Endurance and Sprint Athletes

OpenAIRE

Lukas Cipryan, Gerhard Tschakert, Peter Hofmann

2017-01-01

The purpose of the presented study was to compare acute and post-exercise differences in cardiorespiratory, metabolic, cardiac autonomic, inflammatory and muscle damage responses to high-intensity interval exercise (HIIT) between endurance and sprint athletes. The study group consisted of sixteen highly-trained males (age 22.1 ± 2.5 years) participating in endurance (n = 8) or sprint (n = 8) sporting events. All the participants underwent three exercise sessions: short HIIT (work interval dur...

The influence of successive matches on match-running performance during an under-23 international soccer tournament: The necessity of individual analysis.

Science.gov (United States)

Varley, Matthew C; Di Salvo, Valter; Modonutti, Mattia; Gregson, Warren; Mendez-Villanueva, Alberto

2018-03-01

This study investigated the effects of successive matches on match-running in elite under-23 soccer players during an international tournament. Match-running data was collected using a semi-automated multi-camera tracking system during an international under-23 tournament from all participating outfield players. Players who played 100% of all group stage matches were included (3 matches separated by 72 h, n = 44). Differences in match-running performance between matches were identified using a generalised linear mixed model. There were no clear effects for total, walking, jogging, running, high-speed running and sprinting distance between matches 1 and 3 (effect size (ES); -0.32 to 0.05). Positional analysis found that sprint distance was largely maintained from matches 1 to 3 across all positions. Attackers had a moderate decrease in total, jogging and running distance between matches 1 and 3 (ES; -0.72 to -0.66). Classifying players as increasers or decreasers in match-running revealed that match-running changes are susceptible to individual differences. Sprint performance appears to be maintained over successive matches regardless of playing position. However, reductions in other match-running categories vary between positions. Changes in match-running over successive matches affect individuals differently; thus, players should be monitored on an individual basis.

On the performance of Usain Bolt in the 100 m sprint

Science.gov (United States)

Hernández Gómez, J. J.; Marquina, V.; Gómez, R. W.

2013-09-01

Many university texts on mechanics consider the effect of air drag force, using the slowing down of a parachute as an example. Very few discuss what happens when the drag force is proportional to both u and u2. In this paper we deal with a real problem to illustrate the effect of both terms on the speed of a runner: a theoretical model of the world-record 100 m sprint of Usain Bolt during the 2009 World Championships in Berlin is developed, assuming a drag force proportional to u and to u2. The resulting equation of motion is solved and fitted to the experimental data obtained from the International Association of Athletics Federations, which recorded Bolt's position with a laser velocity guard device. It is worth noting that our model works only for short sprints.

Sprint: The first flight demonstration of the external work system robots

Science.gov (United States)

Price, Charles R.; Grimm, Keith

1995-01-01

The External Works Systems (EWS) 'X Program' is a new NASA initiative that will, in the next ten years, develop a new generation of space robots for active and participative support of zero g external operations. The robotic development will center on three areas: the assistant robot, the associate robot, and the surrogate robot that will support external vehicular activities (EVA) prior to and after, during, and instead of space-suited human external activities respectively. The EWS robotics program will be a combination of technology developments and flight demonstrations for operational proof of concept. The first EWS flight will be a flying camera called 'Sprint' that will seek to demonstrate operationally flexible, remote viewing capability for EVA operations, inspections, and contingencies for the space shuttle and space station. This paper describes the need for Sprint and its characteristics.

Physiological and performance changes from the addition of a sprint interval program to wrestling training.

Science.gov (United States)

Farzad, Babak; Gharakhanlou, Reza; Agha-Alinejad, Hamid; Curby, David G; Bayati, Mahdi; Bahraminejad, Morteza; Mäestu, Jarek

2011-09-01

Increasing the level of physical fitness for competition is the primary goal of any conditioning program for wrestlers. Wrestlers often need to peak for competitions several times over an annual training cycle. Additionally, the scheduling of these competitions does not always match an ideal periodization plan and may require a modified training program to achieve a high level of competitive fitness in a short-time frame. The purpose of this study was to examine the effects of 4 weeks of sprint-interval training (SIT) program, on selected aerobic and anaerobic performance indices, and hormonal and hematological adaptations, when added to the traditional Iranian training of wrestlers in their preseason phase. Fifteen trained wrestlers were assigned to either an experimental (EXP) or a control (CON) group. Both groups followed a traditional preparation phase consisting of learning and drilling technique, live wrestling and weight training for 4 weeks. In addition, the EXP group performed a running-based SIT protocol. The SIT consisted of 6 35-m sprints at maximum effort with a 10-second recovery between each sprint. The SIT protocol was performed in 2 sessions per week, for the 4 weeks of the study. Before and after the 4-week training program, pre and posttesting was performed on each subject on the following: a graded exercise test (GXT) to determine VO(2)max, the velocity associated with V(2)max (νVO(2)max), maximal ventilation, and peak oxygen pulse; a time to exhaustion test (T(max)) at their νVO(2)max; and 4 successive Wingate tests with a 4-minute recovery between each trial for the determination of peak and mean power output (PPO, MPO). Resting blood samples were also collected at the beginning of each pre and posttesting period, before and after the 4-week training program. The EXP group showed significant improvements in VO(2)max (+5.4%), peak oxygen pulse (+7.7%) and T(max) (+32.2%) compared with pretesting. The EXP group produced significant increases

The influence of ego depletion on sprint start performance in athletes without track and field experience.

Science.gov (United States)

Englert, Chris; Persaud, Brittany N; Oudejans, Raôul R D; Bertrams, Alex

2015-01-01

We tested the assumption that ego depletion would affect the sprint start in a sample of N = 38 athletes without track and field experience in an experiment by applying a mixed between- (depletion vs. non-depletion) within- (T1: before manipulation of ego depletion vs. T2: after manipulation of ego depletion) subjects design. We assumed that ego depletion would increase the possibility for a false start, as regulating the impulse to initiate the sprinting movement too soon before the starting signal requires self-control. In line with our assumption, we found a significant interaction as there was only a significant increase in the number of false starts from T1 to T2 for the depletion group while this was not the case for the non-depletion group. We conclude that ego depletion has a detrimental influence on the sprint start in athletes without track and field experience.

Development of repeated sprint ability in talented youth basketball players

NARCIS (Netherlands)

te Wierike, Simon; Lemmink, Koen; de Jong, M.C.; Tromp, E.J.; Vuijk, P.J.; Malina, R.M.; Elferink-Gemser, Marije; Visscher, Chris

2013-01-01

Factors affecting repeated sprint ability (RSA) were evaluated in a mixed-longitudinal sample of 48 elite basketball players 14 to 19 years of age (16.1±1.7 years). Players were observed on six occasions during the 2008-2009 and 2009-2010 seasons. Three basketball-specific field tests were

Development of repeated sprint ability in talented youth basketball players.

NARCIS (Netherlands)

Koen A.P.M. Lemmink; P.J. Vuijk; S.C. te Wierike; C. Visscher; M.T. Elferink-Gemser; M.C. de Jong; R.M. Malina; E.J. Tromp

2013-01-01

Factors affecting repeated sprint ability (RSA) were evaluated in a mixed-longitudinal sample of 48 elite basketball players 14 to 19 years of age (16.1±1.7 years). Players were observed on six occasions during the 2008-2009 and 2009-2010 seasons. Three basketball-specific field tests were

Effects of in-season short-term aerobic and high-intensity interval training program on repeated sprint ability and jump performance in handball players.

Science.gov (United States)

Hermassi, Souhail; Ingebrigtsen, Jørgen; Schwesig, René; Fieseler, Georg; Delank, Karl-Stefan; Chamari, Karim; Shephard, Roy J; Chelly, Mohamed-Souhaiel

2018-01-01

This study examined the effects of a 7-week in-season aerobic and high-intensity interval-training program on performance tests linked to successful handball play (e.g., repeated sprint and jumping ability). Thirty participants (age 17.0±1.2 years, body mass 81.1±3.4 kg, height 1.82±0.07 m) performed a Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1), a squat (SJ) and a Countermovement Jump Test (CMJ), as well as a repeated Sprint Ability Test (RSA). From this, maximal aerobic speed (MAS, reached at the end of the Yo-Yo IR1), jumping ability, best time in a single sprint trial (RSAbest), total time (RSATT) and the performance decrement (RSAdec) during all sprints were calculated. Later, subjects were randomly assigned to a control group (CG; N.=15) performing their normal training schedule (5 weekly sessions of ~90 minutes of handball training) or an experimental group (EG; N.=15). The EG performed two 30 min sessions per week of high-intensity aerobic exercises at 100-130% of MAS in addition to their normal training schedule. A significant improvement in MAS (d=4.1), RSAbest (d=1.9), RSATT (d=1.5) and RSAdec (d=2.3) after the training period was demonstrated. Also, significant interaction effects (time x group) were found for all parameters as the EG significantly improved performances in all tests after training. The greatest interaction effects were observed in MAS (η2=0.811) and CMJ (η2=0.759). No relevant changes in test performances were found in the CG (mean d=-0.02). These results indicate that individually speed-controlled aerobic and interval training is effective for improving specific handball performance.

Effects of Different Post-Activation Potentiation Warm-Ups on Repeated Sprint Ability in Soccer Players from Different Competitive Levels

Directory of Open Access Journals (Sweden)

Sanchez-Sanchez Javier

2018-03-01

Full Text Available This study aimed to compare the effects of a traditional warm-up with two post-activation potentiation (PAP warm-up strategies on the repeated sprint ability (RSA of soccer players from national (NL and regional (RL competitive levels. Sixteen young players (NL, n = 8, age = 20.7 ± 1.4 y, body mass = 68.5 ± 7.0 kg, body height = 177.4 ± 5.2 cm; RL, n = 8, age = 20.8 ± 1.0 y, body mass = 68.7 ± 4.0 kg, body height = 176.6 ± 5.6 cm were recruited to complete a traditional warm-up (CONTROL, a PAP warm-up incorporating squats with a load (~60% 1RM that allowed a high speed (1 m/s of movement and a high number of repetitions (PAP-1, and a PAP warm-up with a load (~90% 1RM that allowed a moderate speed (0.5 m/s of movement and a reduced number of repetitions (PAP-0.5. A RSA test (six 20-m sprints with 20 s of recovery was performed 5 min after the PAP warm-up to assess the effects of the different protocols on the fastest sprint (RSAb and the mean time of all sprints (RSAm. A meaningful improvement of RSA performance was observed with PAP-0.5, attaining a large effect on NL (RSAb, ES = -1.5; RSAm, ES = -1.3 and only a small effect on RL athletes (RSAb and RSAm, ES = -0.2. Moreover, when each RSA sprint performance was compared between NL and RL players, after PAP-0.5 greater performance for all sprints was observed in the NL players. Therefore, adding a heavy strength-based conditioning exercise during the warm-up prior to a RSA test may induce significant performance improvements in NL, but only small effects in RL players.

Effects of Different Post-Activation Potentiation Warm-Ups on Repeated Sprint Ability in Soccer Players from Different Competitive Levels.

Science.gov (United States)

Sanchez-Sanchez, Javier; Rodriguez, Alejandro; Petisco, Cristina; Ramirez-Campillo, Rodrigo; Martínez, Cristian; Nakamura, Fábio Y

2018-03-01

This study aimed to compare the effects of a traditional warm-up with two post-activation potentiation (PAP) warm-up strategies on the repeated sprint ability (RSA) of soccer players from national (NL) and regional (RL) competitive levels. Sixteen young players (NL, n = 8, age = 20.7 ± 1.4 y, body mass = 68.5 ± 7.0 kg, body height = 177.4 ± 5.2 cm; RL, n = 8, age = 20.8 ± 1.0 y, body mass = 68.7 ± 4.0 kg, body height = 176.6 ± 5.6 cm) were recruited to complete a traditional warm-up (CONTROL), a PAP warm-up incorporating squats with a load (~60% 1RM) that allowed a high speed (1 m/s) of movement and a high number of repetitions (PAP-1), and a PAP warm-up with a load (~90% 1RM) that allowed a moderate speed (0.5 m/s) of movement and a reduced number of repetitions (PAP-0.5). A RSA test (six 20-m sprints with 20 s of recovery) was performed 5 min after the PAP warm-up to assess the effects of the different protocols on the fastest sprint (RSAb) and the mean time of all sprints (RSAm). A meaningful improvement of RSA performance was observed with PAP-0.5, attaining a large effect on NL (RSAb, ES = -1.5; RSAm, ES = -1.3) and only a small effect on RL athletes (RSAb and RSAm, ES = -0.2). Moreover, when each RSA sprint performance was compared between NL and RL players, after PAP-0.5 greater performance for all sprints was observed in the NL players. Therefore, adding a heavy strength-based conditioning exercise during the warm-up prior to a RSA test may induce significant performance improvements in NL, but only small effects in RL players.

The Physiological Mechanisms of Performance Enhancement with Sprint Interval Training Differ between the Upper and Lower Extremities in Humans

DEFF Research Database (Denmark)

Zinner, Christoph; Morales-Alamo, David; Ørtenblad, Niels

2016-01-01

To elucidate the mechanisms underlying the differences in adaptation of arm and leg muscles to sprint training, over a period of 11 days 16 untrained men performed six sessions of 4-6 × 30-s all-out sprints (SIT) with the legs and arms, separately, with a 1-h interval of recovery. Limb-specific V...

Sprint and jump performance in elite male soccer players following a 10-week Nordic Hamstring exercise Protocol

DEFF Research Database (Denmark)

Krommes, K.; Petersen, J.; Nielsen, M. B.

2017-01-01

OBJECTIVE: The preseason Nordic Hamstring Protocol (NHP) reduces hamstring strain injuries in football players. Despite persisting injury rates, elite clubs are reluctant to apply the NHP often over concerns of negative impacts on performance. This pilot study investigated if sprint or jump...... split times) and countermovement jump (CMJ height) was measured before the mid-seasonal break and again after 10 weeks of performing the NHP at the end of pre-season. Dropouts were due to transfers and injuries unrelated to performing NHP (NHP = 0, CG = 5). Sprint performance on the short split...... to negatively affect sprint and vertical jump performance outcomes in the present study, while in fact showing some promise for the more explosive characteristics such as the short 5 and 10 m split-times and maximal CMJ height, which all are highly relevant performance parameters in elite football....

Effects of four weeks of repeated sprint training on physiological indices in futsal players

Directory of Open Access Journals (Sweden)

Paulo Cesar do Nascimento

2014-12-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n1p91   The aim of this study was to investigate the effects of short repeated-sprint ability (RSA training on the neuromuscular and physiological indices in U17 futsal players during the competitive period. Fourteen players were divided into two groups: intervention group (n = 8 and control group (n = 6. Both groups performed a repeated maximal sprint test (40-m MST, intermittent shuttle-running test (Carminatti’s test and vertical jumps before and after the training period. The intervention group was submitted to an additional four-week repeated sprints program, twice a week, while the control group maintained their normal training routine. There was no significant interaction between time and groups for all variables analysed (p > 0.05. However, a significant main effect was observed for time (p < 0.01 indicating an increase on speed at heart rate deflection point (VHRDP and the continuous jump performance while the peak lactate (40m-LACpeak and sprint decrement decreased after training, in both groups. Still, based on effect sizes (ES the greater changes with practical relevance were verified for intervention group in important variables such as peak velocity (ES = 0,71, VHRDP (ES = 0,83 and 40m-LACpeak (ES = 1,00. This study showed that RSA-based and normal training routine are equally effective in producing changes in the analysed variables during a short period of intervention. However, the effect size suggests that four weeks of RSA training would be a minimum time that could induce the first changes of futsal player’s physical fitness.

Influence of physical development on start and countermovement jump performance in adolescent sprint athletes.

Science.gov (United States)

Aerenhouts, D; Debaere, S; Hagman, F; Van Gheluwe, B; Delecluse, C; Clarys, P

2013-02-01

The aim of the present study was to describe the effect of physical changes during adolescence on sprint start and countermovement jump (CMJ) performance. Twenty-eight girls and 25 boys (15.0±1.6 and 14.7±1.9 years at start respectively) were measured twice with a one year interval. Anthropometric data allowed skeletal muscle mass (SMM) estimation. Athletes performed a 10m sprint tracked from behind by a laser sensor, with starting blocks measuring propulsion forces. CMJ's were performed on a Kistler force plate. Between the two measurement occasions both genders increased in body height, weight and SMM. In girls and boys, impulse during the push-off, block leaving velocity and times at 5 and 10 m improved significantly. In both genders CMJ absolute power increased but not power.kg-1. Only in boys a higher CMJ was registered on occasion 2. For both genders on both occasions, impulse during the push-off correlated with body weight, SMM and CMJ power (r from .46 to .84), and in boys also with CMJ height and CMJ power.kg-1 (r from 0.43 to 0.76). Boys showed CMJ height and power to correlate with 5 and 10 m times (r from -0.42 to -0.79) and with block leaving velocity, however only on the first data collection (r=0.61 and 0.59, respectively). Sprint start performance is only partly related to muscular development and CMJ could predict start performance in boys only. Sprint start and CMJ rely on technical skills and, therefore, increasing muscularity should be accompanied with sufficient specific training to allow an optimal transfer to start performance.

Vertical and Horizontal Asymmetries are Related to Slower Sprinting and Jump Performance in Elite Youth Female Soccer Players.

Science.gov (United States)

Bishop, Chris; Read, Paul; McCubbine, Jermaine; Turner, Anthony

2018-02-27

Inter-limb asymmetries have been shown to be greater during vertical jumping compared to horizontal jumping. Notable inter-limb differences have also been established at an early age in male youth soccer players. Furthermore, given the multi-planar nature of soccer, establishing between-limb differences from multiple jump tests is warranted. At present, a paucity of data exists regarding asymmetries in youth female soccer players and their effects on physical performance. The aims of this study were to quantify inter-limb asymmetries from unilateral jump tests and examine their effects on speed and jump performance. Nineteen elite youth female soccer players performed a single leg countermovement jump (SLCMJ), single, triple, and crossover hops for distance and a 20 m sprint test. Test reliability was good to excellent (ICC = 0.81-0.99) and variability acceptable (CV = 1.74-5.42%). A one-way ANOVA highlighted larger asymmetries from the SLCMJ compared to all other jump tests (p jump performance (r = -0.47 to -0.58) and vertical asymmetries during the SLCMJ and vertical jump performance (r = -0.47 to -0.53). The results from this study highlight that the SLCMJ appears to be the most appropriate jump test for identifying between-limb differences with values ∼12% showing negative associations with sprint times. Furthermore, larger asymmetries are associated with reduced jump performance and would appear to be direction-specific. Practitioners can use this information as normative data to be mindful of when quantifying inter-limb asymmetries and assessing their potential impact on physical performance in youth female soccer players.

Distances in zero-divisor and total graphs from commutative rings–A survey

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T. Tamizh Chelvam

2016-12-01

Full Text Available There are so many ways to construct graphs from algebraic structures. Most popular constructions are Cayley graphs, commuting graphs and non-commuting graphs from finite groups and zero-divisor graphs and total graphs from commutative rings. For a commutative ring R with non-zero identity, we denote the set of zero-divisors and unit elements of R by Z(R and U(R, respectively. One of the associated graphs to a ring R is the zero-divisor graph; it is a simple graph with vertex set Z(R∖{0}, and two vertices x and y are adjacent if and only if xy=0. This graph was first introduced by Beck, where all the elements of R are considered as the vertices. Anderson and Badawi, introduced the total graph of R, as the simple graph with all elements of R as vertices, and two distinct vertices x and y are adjacent if and only if x+y∈Z(R. For a given graph G, the concept of connectedness, diameter and girth are always of great interest. Several authors extensively studied about the zero-divisor and total graphs from commutative rings. In this paper, we present a survey of results obtained with regard to distances in zero-divisor and total graphs.

Coffee and Caffeine Ingestion Have Little Effect on Repeated Sprint Cycling in Relatively Untrained Males

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Neil Clarke

2016-08-01

Full Text Available The present study investigated the effect of ingesting caffeine-dose-matched anhydrous caffeine or coffee on the performance of repeated sprints. Twelve recreationally active males (mean ± SD age: 22 ± 2 years, height: 1.78 ± 0.07 m, body mass: 81 ± 16 kg completed eighteen 4 s sprints with 116 s recovery on a cycle ergometer on four separate occasions in a double-blind, randomised, counterbalanced crossover design. Participants ingested either 3 mg·kg−1 of caffeine (CAF, 0.09 g·kg−1 coffee, which provided 3 mg·kg−1 of caffeine (COF, a taste-matched placebo beverage (PLA, or a control condition (CON 45 min prior to commencing the exercise protocol. Peak and mean power output and rating of perceived exertion (RPE were recorded for each sprint. There were no significant differences in peak power output (CAF: 949 ± 199 W, COF: 949 ± 174 W, PLA: 971 ± 149 W and CON: 975 ± 170 W; p = 0.872; η P 2 = 0.02 or mean power output (CAF: 873 ± 172 W, COF: 862 ± 44 W, PLA: 887 ± 119 W and CON: 892 ± 143 W; p = 0.819; η P 2 = 0.03 between experimental conditions. Mean RPE was similar for all trials (CAF: 11 ± 2, COF: 11 ± 2, PLA: 11 ± 2 and CON: 11 ± 2; p = 0.927; η P 2 = 0.01. Neither the ingestion of COF or CAF improved repeated sprint cycling performance in relatively untrained males.

Correlação entre o desempenho de jogadores de futebol no teste de sprint de 30m e no teste de salto vertical Correlation between performance of Soccer players in the 30-meter sprint test and in the vertical jump test

Directory of Open Access Journals (Sweden)

Daniel Barbosa Coelho

2011-03-01

Full Text Available O objetivo do estudo foi determinar o nível de correlação entre o desempenho nos 10m iniciais, dos 20m finais e no tempo total do teste de sprint de 30m, com o do salto vertical com contra-movimento (CMJ entre jogadores de futebol. Participaram do estudo 167 jogadores das categorias profissional (N. 94 e júnior (N. 73. Foram determinadas as velocidades dos jogadores em 10m (V10, 20m (V20 e no total de 30m (V30. A habilidade de salto foi avaliada através do CMJ. Para correlacionar os dados, foi utilizado o coeficiente de correlação de Pearson com nível de significância de pThe aim of the present study was to determine the association between the results in the counter movement jump (CMJ and the results in the first 10 meters, in the final 20 meters and the in the total 30 meters of a 30-meter sprint. One-hundred and sixty seven Soccer players from the professional (N. 93 and under twenty (N. 74 categories, from a Brazilian first division Soccer club participated in the study. The sprint test consisted of a 30-meter run timed at the 10-meter and at the 30-meter marks. The jump capacity was assessed through the CMJ. Pearson's correlation (r was used to determine the association between these variables. The significance level adopted was p<.05. The U-20 players presented faster V10 and slower V20 than the professionals (p<.05. The correlation (r between CMJ and V10, V20 and V30 were .239, .370 and .408, respectively, for the U20 group and .381, .381 and .470, respectively, for the professional group. Evaluating the two categories together the correlation were; r= 0,293, 0,386 and 0,441 to V10, V20 and V30 respectively. The correlation between CMJ and V10 was weak and moderate for V20 and V30. In the professional category the correlation between CMJ and all the other parameters was moderate. It is probable that higher correlation values for CMJ and V10 for the professionals could be attributed to specific training effects.

The effect of a sport development programme on sprinting and long ...

African Journals Online (AJOL)

The talented children in both groups then underwent a specific test battery designed for sprinting and long jump. Maturity was determined by means of a maturity questionnaire. The development programme contributed statistically significant to the improvement in flexibility, muscle endurance, 0-40 meter speed and ...

Increased oxidative stress and anaerobic energy release, but blunted Thr172-AMPKα phosphorylation, in response to sprint exercise in severe acute hypoxia in humans.

Science.gov (United States)

Morales-Alamo, David; Ponce-González, Jesús Gustavo; Guadalupe-Grau, Amelia; Rodríguez-García, Lorena; Santana, Alfredo; Cusso, Maria Roser; Guerrero, Mario; Guerra, Borja; Dorado, Cecilia; Calbet, José A L

2012-09-01

AMP-activated protein kinase (AMPK) is a major mediator of the exercise response and a molecular target to improve insulin sensitivity. To determine if the anaerobic component of the exercise response, which is exaggerated when sprint is performed in severe acute hypoxia, influences sprint exercise-elicited Thr(172)-AMPKα phosphorylation, 10 volunteers performed a single 30-s sprint (Wingate test) in normoxia and in severe acute hypoxia (inspired Po(2): 75 mmHg). Vastus lateralis muscle biopsies were obtained before and immediately after 30 and 120 min postsprint. Mean power output and O(2) consumption were 6% and 37%, respectively, lower in hypoxia than in normoxia. O(2) deficit and muscle lactate accumulation were greater in hypoxia than in normoxia. Carbonylated skeletal muscle and plasma proteins were increased after the sprint in hypoxia. Thr(172)-AMPKα phosphorylation was increased by 3.1-fold 30 min after the sprint in normoxia. This effect was prevented by hypoxia. The NAD(+)-to-NADH.H(+) ratio was reduced (by 24-fold) after the sprints, with a greater reduction in hypoxia than in normoxia (P exercise in human skeletal muscle is altered in severe acute hypoxia, which abrogated Thr(172)-AMPKα phosphorylation, likely due to lower LKB1 activation by SIRT1.

Multi Directional Repeated Sprint Is a Valid and Reliable Test for Assessment of Junior Handball Players

Directory of Open Access Journals (Sweden)

Amin Daneshfar

2018-04-01

Full Text Available The aim of the present study was to examine the validity and reliability of a 10 × (6 × 5 m multi-directional repeated sprint ability test (RSM in elite young team handball (TH players. Participants were members of the Iranian national team (n = 20, age 16.4 ± 0.7 years, weight 82.5 ± 5.5 kg, height 184.8 ± 4.6 cm, body fat 15.4 ± 4.3%. The validity of RSM was tested against a 10 × (15 + 15 m repeated sprint ability test (RSA, Yo-Yo Intermittent Recovery test Level 1 (Yo-Yo IR1, squat jump (SJ and countermovement jump (CMJ. To test the reliability of RSM, the participants repeated the testing sessions of RSM and RSA 1 week later. Both RSA and RSM tests showed good to excellent reliability of the total time (TT, best time (BT, and weakest time (WT. The results of the correlation analysis showed significant inverse correlations between maximum aerobic capacity and TT in RSA (r = −0.57, p ≤ 0.05 and RSM (r = −0.76, p ≤ 0.01. There was also a significant inverse correlation between maximum aerobic capacity with fatigue index (FI in RSA test (r = −0.64, p ≤ 0.01 and in RSM test (r = −0.53, p ≤ 0.05. BT, WT, and TT of RSA was largely-to-very largely correlated with BT (r = 0.58, p ≤ 0.01, WT (r = 0.62, p ≤ 0.01, and TT (r = 0.65, p ≤ 0.01 of RSM. BT in RSM was also correlated with FI in RSM (r = 0.88, p ≤ 0.01. In conclusion, based on the findings of the current study, the recently developed RSM test is a valid and reliable test and should be utilized for assessment of repeated sprint ability in handball players.

Multi Directional Repeated Sprint Is a Valid and Reliable Test for Assessment of Junior Handball Players

Science.gov (United States)

Daneshfar, Amin; Gahreman, Daniel E.; Koozehchian, Majid S.; Amani Shalamzari, Sadegh; Hassanzadeh Sablouei, Mozhgan; Rosemann, Thomas; Knechtle, Beat; Nikolaidis, Pantelis T.

2018-01-01

The aim of the present study was to examine the validity and reliability of a 10 × (6 × 5 m) multi-directional repeated sprint ability test (RSM) in elite young team handball (TH) players. Participants were members of the Iranian national team (n = 20, age 16.4 ± 0.7 years, weight 82.5 ± 5.5 kg, height 184.8 ± 4.6 cm, body fat 15.4 ± 4.3%). The validity of RSM was tested against a 10 × (15 + 15 m) repeated sprint ability test (RSA), Yo-Yo Intermittent Recovery test Level 1 (Yo-Yo IR1), squat jump (SJ) and countermovement jump (CMJ). To test the reliability of RSM, the participants repeated the testing sessions of RSM and RSA 1 week later. Both RSA and RSM tests showed good to excellent reliability of the total time (TT), best time (BT), and weakest time (WT). The results of the correlation analysis showed significant inverse correlations between maximum aerobic capacity and TT in RSA (r = −0.57, p ≤ 0.05) and RSM (r = −0.76, p ≤ 0.01). There was also a significant inverse correlation between maximum aerobic capacity with fatigue index (FI) in RSA test (r = −0.64, p ≤ 0.01) and in RSM test (r = −0.53, p ≤ 0.05). BT, WT, and TT of RSA was largely-to-very largely correlated with BT (r = 0.58, p ≤ 0.01), WT (r = 0.62, p ≤ 0.01), and TT (r = 0.65, p ≤ 0.01) of RSM. BT in RSM was also correlated with FI in RSM (r = 0.88, p ≤ 0.01). In conclusion, based on the findings of the current study, the recently developed RSM test is a valid and reliable test and should be utilized for assessment of repeated sprint ability in handball players. PMID:29670536

Match-play demands of elite youth Gaelic football using global positioning system tracking.

Science.gov (United States)

Reilly, Brian; Akubat, Ibrahim; Lyons, Mark; Collins, D Kieran

2015-04-01

Global positioning systems (GPS) technology has made athlete-tracking a convenient and accepted technique to specify movement patterns and physical demands in sport. The purpose of this study was to examine positional demands of elite youth Gaelic football match-play using portable GPS technology to examine movement patterns and heart rates across match periods. Fifty-six elite youth male Gaelic footballers (age, 15 ± 0.66 years) fitted with portable 4-Hz GPS units were observed during 6 competitive matches (60 minutes). Data provided from the GPS unit included total distance, high-intensity (≥17·km·h(-1)) distance, sprint (≥22 km·h(-1)) distance, and total number of sprints. Heart rate was monitored continuously throughout the games. Players covered a mean distance of 5732 ± 1047 m, and the mean intensity of match-play was 85% of the peak heart rate. There was a significant (p = 0.028) drop in the total distance covered in the second half (2783 ± 599 m) compared with the first half (2948 ± 580 m). In particular, there is a noticeable drop in the distance covered in the third quarter of the game (after half-time), which has implications for re-warming up at the end of the half-time interval. There was a highly significant (p < .001) difference in the distance traveled across the 5 positional groups with midfielders covering the greatest total distance (6740 ± 384 m). The significant differences found with respect to positional groups support the implementation of individual, position-specific strength and conditioning programs.

RELIABILITY AND ACCURACY OF 10 HZ GPS DEVICES FOR SHORT-DISTANCE EXERCISE

Directory of Open Access Journals (Sweden)

Julen Castellano

2011-03-01

al., 2009. Logan Plus v.4.0 software was used to synchronize the GPS files with the video, establishing the beginning of action when the participant crossed the initial photocell; this was then added to the duration obtained through the photoelectric cells.The accuracy of data within and between devices is shown in Table 1. The average values are close to those established in tests of 15 m and 30 m, with errors getting smaller when the devices were used over 30 m.The intra-device reliability is depicted in Figure 1, showing greater stability over 30 m than 15 m. The inter-device reliability yielded a CV = 1.3% and CV = 0.7% for sprints over 15 m and 30 m, respectively.To our knowledge this is the first study to assess the reliability and accuracy of GPS devices operating at a sampling frequency of 10 Hz. A further point of note is that studies of intra- and inter-device reliability for the same model of device (and therefore the same sampling rate have traditionally used only two devices (Duffield et al., 2010; Petersen et al., 2009, whereas here a total of nine devices were studied.The distance data were found to be highly accurate and only slightly underestimated by the GPS devices. Furthermore, high intra- and inter-device reliability was observed. Accuracy improved with increased distance, and the mean SEM of 10.9% when running 15 m was reduced by half over 30 m (Table 1. Using similar statistics and methodology, Petersen et al., 2009 found SEM values of between 5% and 24% for MinimaxX devices, and between 3% and 11% with SPI-Pro devices, both at a sampling frequency of 5 Hz. Here, only one device (number 1 produced values above 6% in the 15 m test, while another device (number 2 did so for runs of 30 m. We conclude that the increase in sampling frequency led to increased accuracy of the devices.As regards intra-device reliability, high values were obtained in all cases, and increased when used over 30 m (Figure 1. Some studies have reported differences between

Monte Carlo estimation of total variation distance of Markov chains on large spaces, with application to phylogenetics.

Science.gov (United States)

Herbei, Radu; Kubatko, Laura

2013-03-26

Markov chains are widely used for modeling in many areas of molecular biology and genetics. As the complexity of such models advances, it becomes increasingly important to assess the rate at which a Markov chain converges to its stationary distribution in order to carry out accurate inference. A common measure of convergence to the stationary distribution is the total variation distance, but this measure can be difficult to compute when the state space of the chain is large. We propose a Monte Carlo method to estimate the total variation distance that can be applied in this situation, and we demonstrate how the method can be efficiently implemented by taking advantage of GPU computing techniques. We apply the method to two Markov chains on the space of phylogenetic trees, and discuss the implications of our findings for the development of algorithms for phylogenetic inference.

Effect of cluster set warm-up configurations on sprint performance in collegiate male soccer players.

Science.gov (United States)

Nickerson, Brett S; Mangine, Gerald T; Williams, Tyler D; Martinez, Ismael A

2018-06-01

The purpose of this study was to determine if back squat cluster sets (CS) with varying inter-repetition rest periods would potentiate greater sprint performance compared with a traditional set parallel back squat in collegiate soccer players. Twelve collegiate male soccer players (age, 21.0 ± 2.0 years; height, 180.0 ± 9.0 cm; body mass, 79.0 ± 9.5 kg) performed a 20-m sprint prior to a potentiation complex and at 1, 4, 7, and 10 min postexercise on 3 separate, randomized occasions. On each occasion, the potentiation complex consisted of 1 set of 3 repetitions at 85% 1-repetition maximum (1RM) for the traditional parallel back squat. However, on 1 occasion the 3-repetition set was performed in a traditional manner (i.e., continuously), whereas on the other 2 occasions, 30s (CS 30 ) and 60 s (CS 60 ) of rest were allotted between each repetition. Repeated-measures ANOVA revealed greater (p = 0.022) mean barbell velocity on CS 60 compared with the traditional set. However, faster (p < 0.040) 20-m sprint times were observed for CS 30 (3.15 ± 0.16 s) compared with traditional (3.20 ± 0.17 s) only at 10 min postexercise. No other differences were observed. These data suggest that a single cluster set of 3 repetitions with 30-s inter-repetition rest periods at 85% 1RM acutely improves 20-m sprinting performance. Strength and conditioning professionals and their athletes might consider its inclusion during the specific warm-up to acutely improve athletic performance during the onset (≤10 min) of training or competition.

Does player unavailability affect football teams' match physical outputs? A two-season study of the UEFA champions league.

Science.gov (United States)

Windt, Johann; Ekstrand, Jan; Khan, Karim M; McCall, Alan; Zumbo, Bruno D

2018-05-01

Player unavailability negatively affects team performance in elite football. However, whether player unavailability and its concomitant performance decrement is mediated by any changes in teams' match physical outputs is unknown. We examined whether the number of players injured (i.e. unavailable for match selection) was associated with any changes in teams' physical outputs. Prospective cohort study. Between-team variation was calculated by correlating average team availability with average physical outputs. Within-team variation was quantified using linear mixed modelling, using physical outputs - total distance, sprint count (efforts over 20km/h), and percent of distance covered at high speeds (>14km/h) - as outcome variables, and player unavailability as the independent variable of interest. To control for other factors that may influence match physical outputs, stage (group stage/knockout), venue (home/away), score differential, ball possession (%), team ranking (UEFA Club Coefficient), and average team age were all included as covariates. Teams' average player unavailability was positively associated with the average number of sprints they performed in matches across two seasons. Multilevel models similarly demonstrated that having 4 unavailable players was associated with 20.8 more sprints during matches in 2015/2016, and with an estimated 0.60-0.77% increase in the proportion of total distance run above 14km/h in both seasons. Player unavailability had a possibly positive and likely positive association with total match distances in the two respective seasons. Having more players injured and unavailable for match selection was associated with an increase in teams' match physical outputs. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Gender differences in the physiological responses and kinematic behaviour of elite sprint cross-country skiers.

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Sandbakk, Oyvind; Ettema, Gertjan; Leirdal, Stig; Holmberg, Hans-Christer

2012-03-01

Gender differences in performance by elite endurance athletes, including runners, track cyclists and speed skaters, have been shown to be approximately 12%. The present study was designed to examine gender differences in physiological responses and kinematics associated with sprint cross-country skiing. Eight male and eight female elite sprint cross-country skiers, matched for performance, carried out a submaximal test, a test of maximal aerobic capacity (VO(2max)) and a shorter test of maximal treadmill speed (V (max)) during treadmill roller skiing utilizing the G3 skating technique. The men attained 17% higher speeds during both the VO(2max) and the V (max) tests (P differences that were reduced to 9% upon normalization for fat-free body mass. Furthermore, the men exhibited 14 and 7% higher VO(2max) relative to total and fat-free body mass, respectively (P gender groups. At the same absolute speed, men employed 11% longer cycles at lower rates, and at peak speed, 21% longer cycle lengths (P gender differences in performance and VO(2max) than those reported for comparable endurance sports. These differences reflect primarily the higher VO(2max) and lower percentage of body fat in men, since no gender differences in the ability to convert metabolic rate into work rate and speed were observed. With regards to kinematics, the gender difference in performance was explained by cycle length, not by cycle rate.

Generator exchange is associated with an increased rate of Sprint Fidelis lead failure.

Science.gov (United States)

Lovelock, Joshua D; Patel, Ayesha; Mengistu, Andenet; Hoskins, Michael; El-Chami, Mikhael; Lloyd, Michael S; Leon, Angel; DeLurgio, David; Langberg, Jonathan J

2012-10-01

The Medtronic Sprint Fidelis defibrillator lead is at an increased risk for failure and was recalled in October 2007. Approximately 268,000 leads were implanted, and more than 100,000 patients still have active Fidelis leads. A number of studies have examined the rate and clinical predictors of lead failure, but none has addressed the effect of an implantable cardioverter-defibrillator generator exchange on subsequent lead failure. Although the manufacturer asserts that "Sprint Fidelis performance after device change-out is similar to lead performance without device change-out," published data are lacking. To assess the effect of implantable cardioverter-defibrillator generator exchange on the rate of Fidelis lead failure. A chart review was conducted in patients who underwent implantation of a Fidelis lead. Patients with a functioning Fidelis lead at generator exchange were compared with controls with leads implanted for a comparable amount of time not undergoing ICD replacement. A total of 1366 patients received a Fidelis lead prior to the recall, of which 479 were still actively followed. Seventy-two patients with a functioning lead underwent generator exchange without lead replacement. Following generator replacement, 15 leads failed. Sixty percent of the Fidelis leads failed within 3 months. Generator exchange increased the rate of lead failure compared with matched controls (20.8% vs 2.54%; P exchange is associated with a higher than expected rate of Fidelis lead failure, often within 3 months. The risk-benefit ratio of Fidelis lead replacement at the time of generator exchange may be greater than appreciated. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Sprinting on a running track: a rare cause of a Lisfranc dislocation.

LENUS (Irish Health Repository)

Khan, F

2012-02-03

We present a case report of a young man who sustained a serious foot injury while sprinting in a straight line. We discuss the management of these injuries and emphasise the importance of a high index of suspicion amongst orthopaedic, casualty and radiology trainees.

Repeated Sprint Ability in Young Basketball Players: Multi-direction vs. One-Change of Direction (Part 1)

OpenAIRE

Padulo, Johnny; Bragazzi, Nicola L.; Nikolaidis, Pantelis T.; Dello Iacono, Antonio; Attene, Giuseppe; Pizzolato, Fabio; Dal Pupo, Juliano; Zagatto, Alessandro M.; Oggianu, Marcello; Migliaccio, Gian M.

2016-01-01

The aim of the present study was to examine the reliability of a novel multi-direction repeated sprint ability test (RSM; 10×(6×5-m)) compared with a repeated sprint ability test (RSA) with one change of direction (10×(2×15-m)), and the relationship of the RSM and RSA with Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) and jump performances [squat jump (SJ) and counter-movement-jump (CMJ)]. Thirty-six (male, n=14, female n=22) young basketball players (age 16.0±0.9 yrs) performed the RS...

Effect of sprint cycle training on activities of antioxidant enzymes in human skeletal muscle

DEFF Research Database (Denmark)

Hellsten, Ylva; Apple, F. S.; Sjödin, B.

1996-01-01

(P anaerobic capacity in the trained muscle. The present study demonstrates that intermittent sprint cycle training that induces an enhanced capacity for anaerobic energy generation also improves......The effect of intermittent sprint cycle training on the level of muscle antioxidant enzyme protection was investigated. Resting muscle biopsies, obtained before and after 6 wk of training and 3, 24, and 72 h after the final session of an additional 1 wk of more frequent training, were analyzed...... for activities of the antioxidant enzymes glutathione peroxidase (GPX), glutathione reductase (GR), and superoxide dismutase (SOD). Activities of several muscle metabolic enzymes were determined to assess the effectiveness of the training. After the first 6-wk training period, no change in GPX, GR, or SOD...

Effect of 8 days of a hypergravity condition on the sprinting speed and lower-body power of elite rugby players.

Science.gov (United States)

Barr, Matthew J; Gabbett, Tim J; Newton, Robert U; Sheppard, Jeremy M

2015-03-01

-Sprinting speed and lower-body power are considered to be key physical abilities for rugby players. A method of improving the lower-body power of athletes is simulated hypergravity. This method involves wearing a weighted vest at all times during the day for an extended period of time. There are no studies that have examined the effect of hypergravity on speed or the benefit for rugby players. An experimental group (n = 8) and a control group (n = 7) of national team rugby players took part in the study, which consisted of rugby, conditioning, speed, and strength sessions. The experimental group wore a weighted vest equating to 12% of their body mass for 8 days. All players were tested for speed and lower-body power before, 2 days after, and 9 days after the intervention. Speed testing involved the athletes completing 40-m sprints with timing lights and high-speed video cameras assessing acceleration and maximal velocity sprinting kinematics. Lower-body power was assessed using weighted countermovement jumps (CMJs). No group differences were found for sprinting speed at any point. The experimental group displayed a large decrease in acceleration ground contact time (-0.01 ± 0.005 s, d = 1.07) and a moderate increase in 15-kg CMJ velocity (0.07 ± 0.11 m·s, d = 0.71). Individual responses showed that players in the experimental group had both negative and positive speed and power responses to the training intervention. Simulated hypergravity for 8 days is likely ineffective at improving sprinting speed while undergoing standard rugby training.

Single-leg lateral, horizontal, and vertical jump assessment: reliability, interrelationships, and ability to predict sprint and change-of-direction performance.

Science.gov (United States)

Meylan, Cesar; McMaster, Travis; Cronin, John; Mohammad, Nur Ikhwan; Rogers, Cailyn; Deklerk, Melissa

2009-07-01

The purposes of this study were to determine the reliability of unilateral vertical, horizontal, and lateral countermovement jump assessments, the interrelationship between these tests, and their usefulness as predictors of sprint (10 m) and change-of-direction (COD) performance for 80 men and women physical education students. Jump performance was assessed on a contact mat and sprint, and COD performances were assessed using timing lights. With regard to the reliability statistics, the largest coefficient of variation (CV) was observed for the vertical jump (CV = 6.7-7.2%) of both genders, whereas the sprint and COD assessments had smallest variability (CV = 0.8 to 2.8%). All intraclass correlation coefficients (ICC) were greater than 0.85, except for the men's COD assessment with the alternate leg. The shared variance between the single-leg vertical, horizontal, and lateral jumps for men and women was less than 50%, indicating that the jumps are relatively independent of one another and represent different leg strength/power qualities. The ability of the jumps to predict sprint and COD performance was limited (R2 < 43%). It would seem that the ability to change direction with 1 leg is relatively independent of a COD with the other leg, especially in the women (R < 30%) of this study. However, if 1 jump assessment were selected to predict sprint and COD performance in a test battery, the single-leg horizontal countermovement jump would seem the logical choice, given the results of this study. Many of the findings in this study have interesting diagnostic and training implications for the strength and conditioning coach.

Precooling leg muscle improves intermittent sprint exercise performance in hot, humid conditions.

Science.gov (United States)

Castle, Paul C; Macdonald, Adam L; Philp, Andrew; Webborn, Anthony; Watt, Peter W; Maxwell, Neil S

2006-04-01

We used three techniques of precooling to test the hypothesis that heat strain would be alleviated, muscle temperature (Tmu) would be reduced, and as a result there would be delayed decrements in peak power output (PPO) during exercise in hot, humid conditions. Twelve male team-sport players completed four cycling intermittent sprint protocols (CISP). Each CISP consisted of twenty 2-min periods, each including 10 s of passive rest, 5 s of maximal sprint against a resistance of 7.5% body mass, and 105 s of active recovery. The CISP, preceded by 20 min of no cooling (Control), precooling via an ice vest (Vest), cold water immersion (Water), and ice packs covering the upper legs (Packs), was performed in hot, humid conditions (mean +/- SE; 33.7 +/- 0.3 degrees C, 51.6 +/- 2.2% relative humidity) in a randomized order. The rate of heat strain increase during the CISP was faster in Control than Water and Packs (P body or whole body cooling.

Improvement of Sprint Performance in Wheelchair Sportsmen With Caffeine Supplementation.

Science.gov (United States)

Graham-Paulson, Terri S; Perret, Claudio; Watson, Phil; Goosey-Tolfrey, Victoria L

2016-03-01

Caffeine can be beneficial during endurance and repeated-sprint exercise in able-bodied individuals performing leg or whole-body exercise. However, little evidence exists regarding its effects during upper-body exercise. This study therefore aimed to investigate the effects of caffeine on sprint (SPR) and 4-min maximal-push (PUSH) performance in wheelchair sportsmen. Using a double-blind, placebo-controlled, crossover design, 12 male wheelchair rugby players (age 30.0 ± 7.7 y, body mass 69.6 ± 15.3 kg, training 11.1 ± 3.5 h/wk) completed 2 exercise trials, separated by 7-14 d, 70 min after ingestion of 4 mg/kg caffeine (CAF) or dextrose placebo (PLA). Each trial consisted of four 4-min PUSHes and 3 sets of 3 × 20-m SPRs, each separated by 4 min rest. Participants responded to the Felt Arousal (a measure of perceived arousal), Feeling (a measure of the affective dimension of pleasure/displeasure), and rating-of-perceived-exertion (RPE) scales. Salivary caffeine secretion rates were measured. Average SPR times were faster during CAF than PLA during SPR 1 and SPR 2 (P = .037 and .016). There was no influence of supplementation on PUSHes 2-4 (P > .099); however, participants pushed significantly farther during PUSH 1 after CAF than after PLA (mean ± SD 677 ± 107 and 653 ± 118 m, P = .047). There was no influence of CAF on arousal or RPE scores (P > .132). Feeling scores improved over the course of the CAF trial only (P = .017) but did not significantly differ between trials (P > .167). Pre-warm-up (45 min postingestion) salivary CAF secretion rates were 1.05 ± 0.94 and 0.08 ± 0.05 μg/min for CAF and PLA, respectively. Acute CAF supplementation can improve both 20-m-sprint performance and a 1-off bout of short-term endurance performance in wheelchair sportsmen.

Effect of 8 weeks sprint interval training on serum levels of Adiponectin and insulin in overweight children

Directory of Open Access Journals (Sweden)

Abdolreza Kazemi

2016-04-01

Full Text Available Background: Scientific studies demonstrated that decreased blood Adiponectin level is associated with insulin resistance in obesity. Also it is well documented that exercise training exerts beneficial effects on obesity but there is few study regarding beneficial effects of sprint Interval training (SIT on childhood obesity. This study was intended to investigate the effect of SIT on serum levels of Adiponectin and insulin in overweight children. Material and Methods: In this study thirty-two obese boy (BMI=27 were randomly assigned to sprint Interval Training (SIT (N=16 and control group(C (N=16. Training protocol consisted of 30s and 90s all-out running that performed 3 sessions per week for 8 weeks. Blood samples were measured by ELISA analysis. Data were analyzed using Independent sample t-test. Results: 8 weeks SIT increase serum levels of Adiponectin (P=0.028 and decrease insulin level (P=0.00. This change was directly related to decrease in values of BMI (P=0.01, total cholesterol (P=0.00 and body weight (P=0.02, but significant change in serum levels of HDL (P=0.50, LDL (P=0.17 and TG (P=0.60 wasn’t observed. Conclusion: These findings suggest that SIT may ameliorate the metabolic abnormalities associated with obesity in children probably through elevation of serum Adiponectin level.

Relationship between lower limbs kinematic variables and effectiveness of sprint during maximum velocity phase.

Science.gov (United States)

Struzik, Artur; Konieczny, Grzegorz; Grzesik, Kamila; Stawarz, Mateusz; Winiarski, Sławomir; Rokita, Andrzej

2015-01-01

The aim of the study was to determine the relationships between time of running over a 15-25 m section of a 30-meter run along a straight line and changes in the angle and angular velocity observed in ankle, knee and hip joints. Therefore, the authors attempted to answer the question of whether a technique of lower limbs movement during the phase of sprint maximum velocity significantly correlates with the time of running over this section. A group of 14 young people from the Lower Silesia Voivodeship Team participated in the experiment. A Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using Noraxon MyoMotion system. There were observed statistically significant relationships between sprint time over a section from 15 to 25 m and left hip rotation (positive) and between this time and left and right ankle joint dorsi-plantar flexion (negative). During the maximum velocity phase of a 30 m sprint, the effect of dorsi-plantar flexion performed in the whole range of motion was found to be beneficial. This can be attributed to the use of elastic energy released in the stride cycle. Further, hip rotation should be minimized, which makes the stride aligned more along a line of running (a straight line) instead of from side to side.

Reliability and Usefulness of Linear Sprint Testing in Adolescent Rugby Union and League Players.

Science.gov (United States)

Darrall-Jones, Joshua D; Jones, Ben; Roe, Gregory; Till, Kevin

2016-05-01

The purpose of this study was to evaluate (a) whether there were differences in sprint times at 5, 10, 20, 30, and 40 m between rugby union and rugby league players, (b) determine the reliability and usefulness of linear sprint testing in adolescent rugby players. Data were collected on 28 rugby union and league academy players over 2 testing sessions, with 3-day rest between sessions. Rugby league players were faster at 5 m than rugby union players, with further difference unclear. Sprint time at 10, 20, 30, and 40 m was all reliable (coefficient of variation [CV] = 3.1, 1.8, 2.0, and 1.3%) but greater than the smallest worthwhile change (SWC [0.2 × between-subject SD]), rating the test as marginal for usefulness. Although the test was incapable of detecting the SWC, we recommend that practitioners and researchers use Hopkins' proposed method; whereby plotting the change score of the individual at each split (±typical error [TE] expressed as a CV) against the SWC and visually inspecting whether the TE crosses into the SWC are capable of identifying whether a change is both real (greater than the noise of the test, i.e., >TE) and of practical significance (>SWC). Researchers and practitioners can use the TE and SWC from this study to assess changes in performance of adolescent rugby players when using single beam timing gates.

Effect of sprint training: training once daily versus twice every second day.

Science.gov (United States)

Ijichi, Toshiaki; Hasegawa, Yuta; Morishima, Takuma; Kurihara, Toshiyuki; Hamaoka, Takafumi; Goto, Kazushige

2015-01-01

This study compared training adaptations between once daily (SINGLE) and twice every second day (REPEATED) sprint training, with same number of training sessions. Twenty physically active males (20.9 ± 1.3 yr) were assigned randomly to the SINGLE (n = 10) or REPEATED (n = 10) group. The SINGLE group trained once per day (5 days per week) for 4 weeks (20 sessions in total). The REPEATED group conducted two consecutive training sessions on the same day, separated by a rest period of 1 h (2-3 days per week) for 4 weeks (20 sessions in total). Each training session consisted of three consecutive 30-s maximal pedalling sets with a 10-min rest between sets. Before and after the training period, the power output during two bouts of 30-s maximal pedalling, exercise duration during submaximal pedalling and resting muscle phosphocreatine (PCr) levels were evaluated. Both groups showed significant increases in peak and mean power output during the two 30-s bouts of maximal pedalling after the training period (P every second day improved OBLA during endurance exercise more than the same training once daily.

Living at high altitude in combination with sea-level sprint training increases hematological parameters but does not improve performance in rats.

Science.gov (United States)

Martinez-Bello, Vladimir Essau; Sanchis-Gomar, Fabian; Nascimento, Ana Lucia; Pallardo, Federico V; Ibañez-Sania, Sandra; Olaso-Gonzalez, Gloria; Calbet, Jose Antonio; Gomez-Cabrera, Mari Carmen; Viña, Jose

2011-06-01

The regimen of aerobic training at sea level with recovery at high altitude has been used by athletes to improve performance. However, little is known about the effects of hypoxia when combined with sprint interval training on performance. The aim of the present study was to determine the effect of a "living high-sprint training low" strategy on hemoglobin, hematocrit and erythropoietin levels in rats. We also wanted to test whether the addition of a hypoxic stress to the program of daily treadmill running at high speeds induces expressional adaptations in skeletal muscle and affects performance. The protein content of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), cytochrome C, pyruvate dehydrogenase kinase (PDK1), heat shock protein 70 (HSP70), manganese superoxide dismutase (MnSOD) and citrate synthase activity were determined in different muscle fiber types in our animals (red and white gastrocnemius muscle). We also determined the maximal aerobic velocity (MAV) before and after the training period. A total of 24 male Wistar rats (3 month old) were randomly divided into four experimental groups: the normoxic control group (n = 6), the normoxic trained group (n = 6), the hypoxic control group (12 h pO(2) 12%/12 h pO(2) 21%) (n = 6) and the hypoxic trained group (12 h pO(2) 12%/12 h pO(2) 21%). Living in normobaric hypoxia condition for 21 days significantly increased hemoglobin, hematocrit and erythropoietin levels in both the rest and the trained groups. The trained animals (normoxia and hypoxia) significantly increased their maximal aerobic velocity. No changes were found in the skeletal muscle in PGC-1α, cytochrome C, PDK1, HSP70, MnSOD protein content and in the citrate synthase activity in any experimental group. Regardless of whether it is combined with sprint interval training or not, after 21 days of living at high altitude we found a significant increase in the hematological values determined in our study. However, contrary to

Comparative Effects of In-Season Full-Back Squat, Resisted Sprint Training, and Plyometric Training on Explosive Performance in U-19 Elite Soccer Players.

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de Hoyo, Moises; Gonzalo-Skok, Oliver; Sañudo, Borja; Carrascal, Claudio; Plaza-Armas, Jose R; Camacho-Candil, Fernando; Otero-Esquina, Carlos

2016-02-01

The aim of this study was to analyze the effects of 3 different low/moderate load strength training methods (full-back squat [SQ], resisted sprint with sled towing [RS], and plyometric and specific drills training [PLYO]) on sprinting, jumping, and change of direction (COD) abilities in soccer players. Thirty-two young elite male Spanish soccer players participated in the study. Subjects performed 2 specific strength training sessions per week, in addition to their normal training sessions for 8 weeks. The full-back squat protocol consisted of 2-3 sets × 4-8 repetitions at 40-60% 1 repetition maximum (∼ 1.28-0.98 m · s(-1)). The resisted sprint training was compounded by 6-10 sets × 20-m loaded sprints (12.6% of body mass). The plyometric and specific drills training was based on 1-3 sets × 2-3 repetitions of 8 plyometric and speed/agility exercises. Testing sessions included a countermovement jump (CMJ), a 20-m sprint (10-m split time), a 50-m (30-m split time) sprint, and COD test (i.e., Zig-Zag test). Substantial improvements (likely to almost certainly) in CMJ (effect size [ES]: 0.50-0.57) and 30-50 m (ES: 0.45-0.84) were found in every group in comparison to pretest results. Moreover, players in PLYO and SQ groups also showed substantial enhancements (likely to very likely) in 0-50 m (ES: 0.46-0.60). In addition, 10-20 m was also improved (very likely) in the SQ group (ES: 0.61). Between-group analyses showed that improvements in 10-20 m (ES: 0.57) and 30-50 m (ES: 0.40) were likely greater in the SQ group than in the RS group. Also, 10-20 m (ES: 0.49) was substantially better in the SQ group than in the PLYO group. In conclusion, the present strength training methods used in this study seem to be effective to improve jumping and sprinting abilities, but COD might need other stimulus to achieve positive effects.

EFFECT OF PRE-COOLING ON REPEAT-SPRINT PERFORMANCE IN SEASONALLY ACCLIMATISED MALES DURING AN OUTDOOR SIMULATED TEAM-SPORT PROTOCOL IN WARM CONDITIONS

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Carly J. Brade

2013-09-01

Full Text Available Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10. They performed two trials, one with precooling (PC; ice slushy and cooling jacket and another without (CONT. Trials began with a 30-min baseline/cooling period followed by an 80 min repeat-sprint protocol, comprising 4 x 20-min quarters, with 2 x 5-min quarter breaks and a 10-min half-time recovery/cooling period. A clear and substantial (negative; PC slower effect was recorded for first quarter circuit time. Clear and trivial effects were recorded for overall circuit time, third and fourth quarter sprint times and fourth quarter best sprint time, otherwise unclear and trivial effects were recorded for remaining performance variables. Core temperature was moderately lower (Cohen's d=0.67; 90% CL=-1.27, 0.23 in PC at the end of the precooling period and quarter 1. No differences were found for mean skin temperature, heart rate, thermal sensation, or rating of perceived exertion, however, moderate Cohen's d effect sizes suggested a greater sweat loss in PC compared with CONT. In conclusion, repeat- sprint performance was neither clearly nor substantially improved in seasonally acclimatised players by using a combination of internal and external cooling methods prior to and during exercise performed in the field in warm, dry conditions. Of practical importance, precooling appears unnecessary for repeat-sprint performance if athletes are seasonally acclimatised or artificially acclimated to heat, as it provides no additional benefit

Sprint Running Performance and Technique Changes in Athletes During Periodized Training: An Elite Training Group Case Study.

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Bezodis, Ian N; Kerwin, David G; Cooper, Stephen-Mark; Salo, Aki I T

2017-11-15

To understand how training periodization influences sprint performance and key step characteristics over an extended training period in an elite sprint training group. Four sprinters were studied during five months of training. Step velocities, step lengths and step frequencies were measured from video of the maximum velocity phase of training sprints. Bootstrapped mean values were calculated for each athlete for each session and 139 within-athlete, between-session comparisons were made with a repeated measures ANOVA. As training progressed, a link in the changes in velocity and step frequency was maintained. There were 71 between-session comparisons with a change in step velocity yielding at least a large effect size (>1.2), of which 73% had a correspondingly large change in step frequency in the same direction. Within-athlete mean session step length remained relatively constant throughout. Reductions in step velocity and frequency occurred during training phases of high volume lifting and running, with subsequent increases in step velocity and frequency happening during phases of low volume lifting and high intensity sprint work. The importance of step frequency over step length to the changes in performance within a training year was clearly evident for the sprinters studied. Understanding the magnitudes and timings of these changes in relation to the training program is important for coaches and athletes. The underpinning neuro-muscular mechanisms require further investigation, but are likely explained by an increase in force producing capability followed by an increase in the ability to produce that force rapidly.

Muscle oxygen changes following Sprint Interval Cycling training in elite field hockey players.

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Ben Jones

Full Text Available This study examined the effects of Sprint Interval Cycling (SIT on muscle oxygenation kinetics and performance during the 30-15 intermittent fitness test (IFT. Twenty-five women hockey players of Olympic standard were randomly selected into an experimental group (EXP and a control group (CON. The EXP group performed six additional SIT sessions over six weeks in addition to their normal training program. To explore the potential training-induced change, EXP subjects additionally completed 5 x 30s maximal intensity cycle testing before and after training. During these tests near-infrared spectroscopy (NIRS measured parameters; oxyhaemoglobin + oxymyoglobin (HbO2+ MbO2, tissue deoxyhaemoglobin + deoxymyoglobin (HHb+HMb, total tissue haemoglobin (tHb and tissue oxygenation (TSI % were taken. In the EXP group (5.34 ± 0.14 to 5.50 ± 0.14 m.s(-1 but not the CON group (pre = 5.37 ± 0.27 to 5.39 ± 0.30 m.s(-1 significant changes were seen in the 30-15 IFT performance. EXP group also displayed significant post-training increases during the sprint cycling: ΔTSI (-7.59 ± 0.91 to -12.16 ± 2.70%; ΔHHb+HMb (35.68 ± 6.67 to 69.44 ± 26.48 μM.cm; and ΔHbO2+ MbO2 (-74.29 ± 13.82 to -109.36 ± 22.61 μM.cm. No significant differences were seen in ΔtHb (-45.81 ± 15.23 to -42.93 ± 16.24. NIRS is able to detect positive peripheral muscle oxygenation changes when used during a SIT protocol which has been shown to be an effective training modality within elite athletes.

Isometric Mid-Thigh Pull Performance Is Associated With Athletic Performance And Sprinting Kinetics In Division I Men And Women's Basketball Players.

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Townsend, Jeremy R; Bender, David; Vantrease, William; Hudy, John; Huet, Kevin; Williamson, Cassie; Bechke, Emily; Serafini, Paul; Mangine, Gerald T

2017-07-31

To examine the relationships between isometric mid-thigh pull (IMTP) force, athletic performance measures, and sprint kinetics in Division I men's and women's basketball players. Twenty-three (male = 8, female = 15) division 1 basketball players completed a maximal 20-m sprint trial while tethered to a device which provided kinetic feedback (peak and average sprinting power, velocity and force). Additionally, one repetition-maximal (1RM) front squat, 1RM hang clean, vertical jump height, and agility (pro-agility and lane agility) tests were performed. Rate of force development (RFD) at 50ms, 100ms, 150ms, 200ms and 250ms of IMTP, as well as peak force (PF) were also collected. Pearson product-moment correlation analysis was used to examine the relationships between these measures. Significant (p training.

High-speed running and sprinting as an injury risk factor in soccer: Can well-developed physical qualities reduce the risk?

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Malone, Shane; Owen, Adam; Mendes, Bruno; Hughes, Brian; Collins, Kieran; Gabbett, Tim J

2018-03-01

This study investigated the association between high-speed running (HSR) and sprint running (SR) and injuries within elite soccer players. The impact of intermittent aerobic fitness as measured by the end speed of the 30-15 intermittent fitness test (30-15V IFT ) and high chronic workloads (average 21-day) as potential mediators of injury risk were also investigated. Observational Cohort Study. 37 elite soccer players from one elite squad were involved in a one-season study. Training and game workloads (session-RPE×duration) were recorded in conjunction with external training loads (using global positioning system technology) to measure the HSR (>14.4kmh -1 ) and SR (>19.8kmh -1 ) distance covered across weekly periods during the season. Lower limb injuries were also recorded. Training load and GPS data were modelled against injury data using logistic regression. Odds ratios (OR) were calculated with 90% confidence intervals based on 21-day chronic training load status (sRPE), aerobic fitness, HSR and SR distance with these reported against a reference group. Players who completed moderate HSR (701-750-m: OR: 0.12, 90%CI: 0.08-0.94) and SR distances (201-350-m: OR: 0.54, 90%CI: 0.41-0.85) were at reduced injury risk compared to low HSR (≤674-m) and SR (≤165-m) reference groups. Injury risk was higher for players who experienced large weekly changes in HSR (351-455-m; OR: 3.02; 90%CI: 2.03-5.18) and SR distances (between 75-105-m; OR: 6.12, 90%CI: 4.66-8.29). Players who exerted higher chronic training loads (≥2584 AU) were at significantly reduced risk of injury when they covered 1-weekly HSR distances of 701-750m compared to the reference group of soccer players. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Six Sessions of Sprint Interval Training Improves Running Performance in Trained Athletes.

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Koral, Jerome; Oranchuk, Dustin J; Herrera, Roberto; Millet, Guillaume Y

2018-03-01

Koral, J, Oranchuk, DJ, Herrera, R, and Millet, GY. Six sessions of sprint interval training improves running performance in trained athletes. J Strength Cond Res 32(3): 617-623, 2018-Sprint interval training (SIT) is gaining popularity with endurance athletes. Various studies have shown that SIT allows for similar or greater endurance, strength, and power performance improvements than traditional endurance training but demands less time and volume. One of the main limitations in SIT research is that most studies were performed in a laboratory using expensive treadmills or ergometers. The aim of this study was to assess the performance effects of a novel short-term and highly accessible training protocol based on maximal shuttle runs in the field (SIT-F). Sixteen (12 male, 4 female) trained trail runners completed a 2-week procedure consisting of 4-7 bouts of 30 seconds at maximal intensity interspersed by 4 minutes of recovery, 3 times a week. Maximal aerobic speed (MAS), time to exhaustion at 90% of MAS before test (Tmax at 90% MAS), and 3,000-m time trial (TT3000m) were evaluated before and after training. Data were analyzed using a paired samples t-test, and Cohen's (d) effect sizes were calculated. Maximal aerobic speed improved by 2.3% (p = 0.01, d = 0.22), whereas peak power (PP) and mean power (MP) increased by 2.4% (p = 0.009, d = 0.33) and 2.8% (p = 0.002, d = 0.41), respectively. TT3000m was 6% shorter (p training in the field significantly improved the 3,000-m run, time to exhaustion, PP, and MP in trained trail runners. Sprint interval training in the field is a time-efficient and cost-free means of improving both endurance and power performance in trained athletes.

Effects of synchronous versus asynchronous mode of propulsion on wheelchair basketball sprinting.

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Faupin, Arnaud; Borel, Benoit; Meyer, Christophe; Gorce, Philippe; Watelain, Eric

2013-11-01

This study aimed to first investigate synchronous (SYN) versus asynchronous (ASY) mode of propulsion and, second, investigate the wheel camber effects on sprinting performance as well as temporal parameters. Seven wheelchair basketball players performed four maximal eight-second sprints on a wheelchair ergometer. They repeated the test according to two modes of propulsion (SYN and ASY) and two wheel cambers (9° and 15°). The mean maximal velocity and push power output was greater in the synchronous mode compared to the asynchronous mode for both camber angles. However, the fluctuation in the velocity profile is inferior for ASY versus SYN mode for both camber angles. Greater push time/cycle time (Pt/Ct) and arm frequency (AF) for synchronous mode versus asynchronous mode and inversely, lesser Ct and rest time (Rt) values for the synchronous mode, for which greater velocity were observed. SYN mode leads to better performance than ASY mode in terms of maximal propulsion velocity. However, ASY propulsion allows greater continuity of the hand-rim force application, reducing fluctuations in the velocity profile. The camber angle had no effect on ASY and SYN mean maximal velocity and push power output. The study of wheelchair propulsion strategies is important for better understanding physiological and biomechanical impacts of wheelchair propulsion for individuals with disabilities. From a kinematical point of view, this study highlights synchronous mode of propulsion to be more efficient, with regards to mean maximal velocity reaching during maximal sprinting exercises. Even if this study focuses on well-trained wheelchair athletes, results from this study could complement the knowledge on the physiological and biomechanical adaptations to wheelchair propulsion and therefore, might be interesting for wheelchair modifications for purposes of rehabilitation.

Effects of the Nordic Hamstring exercise on sprint capacity in male football players

DEFF Research Database (Denmark)

Ishøi, Lasse; Hölmich, Per; Aagaard, Per

2018-01-01

This assessor-blinded, randomized controlled superiority trial investigated the efficacy of the 10-week Nordic Hamstring exercise (NHE) protocol on sprint performance in football players. Thirty-five amateur male players (age: 17-26 years) were randomized to a do-as-usual control group (CG; n = 1...

Beneficial Effects of New Zealand Blackcurrant Extract on Maximal Sprint Speed during the Loughborough Intermittent Shuttle Test

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Mark ET Willems

2016-08-01

Full Text Available New Zealand blackcurrant (NZBC extract has been shown to enhance high-intensity intermittent treadmill running. We examined the effects of NZBC extract during the Loughborough Intermittent Shuttle Test (LIST which involves 5 × 15 min blocks with intermittent 15-m maximal sprints, interspersed by moderate and high-intensity running to simulate team sport activity, and a subsequent run to exhaustion. Thirteen males (age: 22 ± 1 year, V ˙ O 2 max : 50 ± 5 mL·kg−1·min−1 participated in three indoor sessions (T: 24 ± 3 °C, humidity: 52% ± 9%. In the first session, a multistage fitness test was completed to determine peak running speed and estimate V ˙ O 2 max . Participants consumed NZBC extract in capsules (300 mg·day−1 CurraNZ™ or placebo (PL (300 mg·day−1 microcrystalline cellulose M102 for seven days in a double-blind, randomized, cross-over design (wash-out at least seven days. NZBC extract did not affect average 15-m sprint times in each block. NZBC reduced slowing of the fastest sprint between block 1 and 5 (PL: 0.12 ± 0.07 s; NZBC: 0.06 ± 0.12 s; p < 0.05. NZBC extract had no effect on heart rate, vertical jump power, lactate and time to exhaustion (PL: 13.44 ± 8.09 min, NZBC: 15.78 ± 9.40 min, p > 0.05. However, eight participants had higher running times to exhaustion when consuming NZBC extract. New Zealand blackcurrant extract may enhance performance in team sports with repeated maximal sprints.

Low dose creatine supplementation enhances sprint phase of 400 meters swimming performance.

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Anomasiri, Wilai; Sanguanrungsirikul, Sompol; Saichandee, Pisut

2004-09-01

This study demonstrated the effect of low dose creatine supplement (10 g. per day) on the sprinting time in the last 50 meters of 400 meters swimming competition, as well as the effect on exertion. Nineteen swimmers in the experimental group received creatine monohydrate 5 g with orange solution 15 g, twice per day for 7 days and nineteen swimmers in the control group received the same quantity of orange solution. The results showed that the swimmers who received creatine supplement lessened the sprinting time in the last 50 meters of 400 meters swimming competition than the control group. (p<0.05). The results of Wingate test (anaerobic power, anaerobic capacity and fatigue index) compared between pre and post supplementation. There was significant difference at p<0.05 in the control group from training effect whereas there was significant difference at p<0.000 from training effect and creatine supplement in the experiment group. Therefore, the creatine supplement in amateur swimmers in the present study enhanced the physical performance up to the maximum capacity.

78 FR 19158 - Safety Zone; USA Triathlon, Milwaukee Harbor, Milwaukee, WI

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2013-03-29

... have minimal impact on the economy, will not interfere with other agencies, will not adversely alter... Milwaukee Harbor due to the 2013 and 2014 Olympic and Sprint Distance National Championships. This proposed... the 2013 and 2014 Olympic and Sprint Distance National Championships. DATES: Comments and related...

A passive heat maintenance strategy implemented during a simulated half-time improves lower body power output and repeated sprint ability in professional Rugby Union players.

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Mark Russell

Full Text Available Reduced physical performance has been observed following the half-time period in team sports players, likely due to a decrease in muscle temperature during this period. We examined the effects of a passive heat maintenance strategy employed between successive exercise bouts on core temperature (Tcore and subsequent exercise performance. Eighteen professional Rugby Union players completed this randomised and counter-balanced study. After a standardised warm-up (WU and 15 min of rest, players completed a repeated sprint test (RSSA 1 and countermovement jumps (CMJ. Thereafter, in normal training attire (Control or a survival jacket (Passive, players rested for a further 15 min (simulating a typical half-time before performing a second RSSA (RSSA 2 and CMJ's. Measurements of Tcore were taken at baseline, post-WU, pre-RSSA 1, post-RSSA 1 and pre-RSSA 2. Peak power output (PPO and repeated sprint ability was assessed before and after the simulated half-time. Similar Tcore responses were observed between conditions at baseline (Control: 37.06±0.05°C; Passive: 37.03±0.05°C and for all other Tcore measurements taken before half-time. After the simulated half-time, the decline in Tcore was lower (-0.74±0.08% vs. -1.54±0.06%, p<0.001 and PPO was higher (5610±105 W vs. 5440±105 W, p<0.001 in the Passive versus Control condition. The decline in PPO over half-time was related to the decline in Tcore (r = 0.632, p = 0.005. In RSSA 2, best, mean and total sprint times were 1.39±0.17% (p<0.001, 0.55±0.06% (p<0.001 and 0.55±0.06% (p<0.001 faster for Passive versus Control. Passive heat maintenance reduced declines in Tcore that were observed during a simulated half-time period and improved subsequent PPO and repeated sprint ability in professional Rugby Union players.

Effect of formoterol, a long-acting β2-adrenergic agonist, on muscle strength and power output, metabolism and fatigue during maximal sprinting in men

DEFF Research Database (Denmark)

Kalsen, Anders; Hostrup, Morten; Backer, Vibeke

2016-01-01

The aim was to investigate the effect of the long-acting β2-adrenergic agonist formoterol on muscle strength and power output, muscle metabolism and phosphorylation of CaMKII Thr(287) and FXYD1 during maximal sprinting. In a double-blind crossover study, thirteen males (VO2max: 45.0±0.2 (mean±SE) m......L min(-1) kg(-1)) performed a 30-s cycle ergometer sprint after inhalation of either 54 µg formoterol (FOR) or placebo (PLA). Before and after the sprint, muscle biopsies were collected from vastus lateralis and maximal voluntary contraction (MVC) and contractile properties of quadriceps were measured...

The Effects of Land-Use Patterns on Home-Based Tour Complexity and Total Distances Traveled: A Path Analysis

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João de Abreu e Silva

2018-03-01

Full Text Available This work studies the relationships between the number of complex tours (with one or more intermediate stops and simple home-based tours, total distances traveled by mode, and land-use patterns both at the residence and at the workplace using path analysis. The model includes commuting distance, car ownership and motorcycle ownership, which are intermediate variables in the relationship between land use, tour complexity and distances traveled by mode. The dataset used here was collected in a region comprising four municipalities located in the north of Portugal that are made up of urban areas, their sprawling suburbs, and surrounding rural hinterland. The results confirm the association between complex tours and higher levels of car use. Land-use patterns significantly affect travelled distances by mode either directly and indirectly via the influence of longer-term decisions like vehicle ownership and commuting distance. The results obtained highlight the role of socioeconomic variables in influencing tour complexity; in particular, households with children, household income, and workers with a college degree tend to do more complex tours. Land-use patterns mediate the effects of tour complexity on the kilometers travelled by different modes. Increasing densities in central areas, and particularly the concentration of jobs, have relevant benefits by reducing car kilometers driven.

Recruitment strategies and challenges in a large intervention trial: Systolic Blood Pressure Intervention Trial (SPRINT)

Science.gov (United States)

Ramsey, Thomas M; Snyder, Joni K; Lovato, Laura C; Roumie, Christianne L; Glasser, Steven P; Cosgrove, Nora M; Olney, Christine M; Tang, Rocky H; Johnson, Karen C; Still, Carolyn H; Gren, Lisa H; Childs, Jeffery C; Crago, Osa L; Summerson, John H; Walsh, Sandy M; Perdue, Letitia H; Bankowski, Denise M; Goff, David C

2016-01-01

Background The Systolic Blood Pressure Intervention Trial (SPRINT) is a multicenter, randomized clinical trial of 9,361 participants with hypertension who are ≥ 50 years old. The trial is designed to evaluate the effect of intensive systolic blood pressure control (systolic blood pressure goal recruitment strategies and lessons learned during recruitment of the SPRINT cohort and five targeted participant subgroups: pre-existing cardiovascular disease, pre-existing chronic kidney disease, age ≥ 75 years, women, and minorities. Methods In collaboration with the National Institutes of Health Project Office and SPRINT Coordinating Center, five Clinical Center Networks oversaw clinical site selection, recruitment, and trial activities. Recruitment began November 8, 2010 and ended March 15, 2013 (about 28 months). Various recruitment strategies were used, including mass mailing, brochures, referrals from healthcare providers or friends, posters, newspaper ads, radio ads, and electronic medical record searches. Results Recruitment was scheduled to last 24 months to enroll a target of 9,250 participants; in just over 28 months, the trial enrolled 9,361 participants. The trial screened 14,692 volunteers, with 33% of initial screens originating from the use of mass mailing lists. Screening results show that participants also responded to recruitment efforts through referral by SPRINT staff, healthcare providers, or friends (45%); brochures or posters placed in clinic waiting areas (15%); and television, radio, newspaper, internet ads, or toll-free numbers (8%). The overall recruitment yield (number randomized /number screened) was 64% (9,361 randomized /14,692 screened), 77% for those with cardiovascular disease, 79% for those with chronic kidney disease, 70% for those age ≥ 75 years, 55% for women, and 61% for minorities. As recruitment was observed to lag behind expectations, additional clinics were included and inclusion criteria were broadened, keeping event rates

78 FR 31415 - Safety Zone; USA Triathlon; Milwaukee Harbor, Milwaukee, WI

Science.gov (United States)

2013-05-24

... minimal impact on the economy, will not interfere with other agencies, will not adversely alter the budget... due to the 2013 and 2014 Olympic and Sprint Distance National Championships. This safety zone is... Olympic and Sprint Distance National Championships. DATES: This final rule is effective from August 1...

Butterfly Sprint Swimming Technique, Analysis of Somatic and Spatial-Temporal Coordination Variables

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Strzała Marek

2017-12-01

Full Text Available The aim of this study was to investigate somatic properties and force production of leg extensor muscles measured in the countermovement jump test (CMJ, as well as to analyse kinematic variables of sprint surface butterfly swimming. Thirty-four male competitive swimmers were recruited with an average age of 19.3 ± 1.83 years. Their average body height (BH was 183.7 ± 5.93 cm, body fat content 10.8 ± 2.64% and body mass (BM 78.3 ± 5.0 kg. Length measurements of particular body segments were taken and a counter movement jump (CMJ as well as an all-out 50 m butterfly speed test were completed. The underwater movements of the swimmers’ bodies were recorded with a digital camera providing side-shots. We registered a significant relationship between body mass (r = 0.46, lean body mass (r = 0.48 and sprint surface butterfly swimming (VSBF. The anaerobic power measured in the CMJ test, total body length (TBL as well as upper and lower extremity length indices did not influence swimming speed significantly. The temporal entry-kick index (the time ratio between the first kick and arm entry significantly influenced VSBF (r = -0.45. Similarly, medium power of the coefficient was indicated between a stroke rate kinematics (SR, b duration of the first leg kick (LP1, c air phase duration of arm recovery (Fly-arm, and VSBF (r = 0.40; r = 0.40 and r = 0.41, respectively. The entry-kick temporal index showed that, in the butterfly cycle, an appropriately early executed initial kick when compared to arm entry was associated with a longer arm propulsion phase, which in turn was associated with minimizing resistive gliding phases and enabled relatively longer and less resistive air arm recovery (higher value of the fly-arm index. The higher value of SR kinematic was another important element of the best butterfly results in this study.

Mechanics of the human hamstring muscles during sprinting.

Science.gov (United States)

Schache, Anthony G; Dorn, Tim W; Blanch, Peter D; Brown, Nicholas A T; Pandy, Marcus G

2012-04-01

An understanding of hamstring mechanics during sprinting is important for elucidating why these muscles are so vulnerable to acute strain-type injury. The purpose of this study was twofold: first, to quantify the biomechanical load (specifically, musculotendon strain, velocity, force, power, and work) experienced by the hamstrings across a full stride cycle; and second, to determine how these parameters differ for each hamstring muscle (i.e., semimembranosus (SM), semitendinosus (ST), biceps femoris long head (BF), biceps femoris short head (BF)). Full-body kinematics and ground reaction force data were recorded simultaneously from seven subjects while sprinting on an indoor running track. Experimental data were integrated with a three-dimensional musculoskeletal computer model comprised of 12 body segments and 92 musculotendon structures. The model was used in conjunction with an optimization algorithm to calculate musculotendon strain, velocity, force, power, and work for the hamstrings. SM, ST, and BF all reached peak strain, produced peak force, and formed much negative work (energy absorption) during terminal swing. The biomechanical load differed for each hamstring muscle: BF exhibited the largest peak strain, ST displayed the greatest lengthening velocity, and SM produced the highest peak force, absorbed and generated the most power, and performed the largest amount of positive and negative work. As peak musculotendon force and strain for BF, ST, and SM occurred around the same time during terminal swing, it is suggested that this period in the stride cycle may be when the biarticular hamstrings are at greatest injury risk. On this basis, hamstring injury prevention or rehabilitation programs should preferentially target strengthening exercises that involve eccentric contractions performed with high loads at longer musculotendon lengths.

Cobalt-60 total body irradiation dosimetry at 220 cm source-axis distance

International Nuclear Information System (INIS)

Glasgow, G.P.; Mill, W.B.

1980-01-01

Adults with acute leukemia are treated with cyclophosphamide and total body irradiation (TBI) followed by autologous marrow transplants. For TBI, patients seated in a stand angled 45 0 above the floor are treated for about 2 hours at 220 cm source-axis distance (SAD) with sequential right and left lateral 87 cm x 87 cm fields to a 900 rad mid-pelvic dose at about 8 rad/min using a 5000 Ci cobalt unit. Maximum (lateral) to minimum (mid-plane) dose ratios are: hips--1.15, shoulders--1.30, and head--1.05, which is shielded by a compensator filter. Organ doses are small intestine, liver and kidneys--1100 rad, lung--1100 to 1200 rad, and heart--1300 rad. Verification dosimetry reveals the prescribed dose is delivered to within +-5%. Details of the dosimetry of this treatment are presented

Comparison of Sprint Reaction and Visual Reaction Times of Athletes in Different Branches

Science.gov (United States)

Akyüz, Murat; Uzaldi, Basar Basri; Akyüz, Öznur; Dogru, Yeliz

2017-01-01

The aims of this study are to analyse sprint reaction and visual reaction times of female athletes of different branches competing in Professional leagues and to show the differences between them. 42 voluntary female athletes from various branches of Professional leagues of Istanbul (volleyball, basketball, handball) were included in the…

Establishing a Practical Treadmill Sprint as an Alternative to the Wingate Anaerobic Test

Science.gov (United States)

McKie, Greg L.; Islam, Hashim; Townsend, Logan K.; Howe, Greg J.; Hazell, Tom J.

2018-01-01

This study examined the validity and reliability of a 30-second running sprint test using two non-motorized treadmills compared to the established Wingate Anaerobic Test. Twenty-four participants completed three sessions in a randomized order on a: (1) manual mode treadmill (Woodway); (2) specialized interval training treadmill (HiTrainer); and…

SAFIPA-Meraka Institute code-sprints program; a mechanism to enhance the development capacity of emerging developers – observations and lessons learned

CSIR Research Space (South Africa)

Coetzee, L

2010-05-01

Full Text Available -MERAKA code-sprints program, a possibility for development is identified. NAP, an initiative to enhance inclusion and empower persons with disabilities, has shown that initiatives need to come from within the community to succeed. A popular slogan... ownership of development efforts. This paper investigates the feasibility of the “ICT for Society through Society” paradigm at the hand of the SAFIPA-MERAKA code-sprints program, an analysis of the Information and Communications Technology...

Effect of Caffeine Contained in Sports Drink on Hormones Producing Energy Following Sprint Test Performance in Male Soccer Players

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Mohammad Fayiz Abumoh'd

2016-05-01

Full Text Available This study investigated the effect of caffeine contained in sports drink on hormones producing energy and sprint test performance in male soccer players. Twelve participants (25.97 ± 2.70 y performed the test under thre e conditions (one week apart: caffeine with sports drink (SD-CAF, sports drink (SD, and placebo (PLA. Using a double-blind, placebo-controlled, randomized, crossover protocol, participants performed SD-CAF trial (5 mg/kg of caffeine contained in 300 ml of sports drink 30 minutes prior to sprinting test (7 × 30 m, SD trial (solely 300 ml of sports drink 30 minutes prior to sprinting test, or placebo. Blood analysis indicated significantly higher level of free thyroxine in SD-CAF (21.450 ± 3.048 compared to SD (18.742 ± 1.151 and PLA (16.983 ± 1.783. Similar findings existed regarding insulin (P 0.05. No significant differences were observed between trials in first–fourth repetitions (P > 0.05. Time of fifth-seventh repetitions were significantly lower in SD-CAF compared to SD and PLA (P < 0.05, and were significantly lower in SD than that in PLA (P < 0.05. The time of 7th repetition was (4.331 ± 0.210, 4.610 ± 0.197, 4.81 6 ± 0.171 s for SD-CAF, SD, and PLA, respectively; P < 0.05. In conclusion, caffeine interferes hormones that are responsible for producing energy which in turn have a positive effect on repeated sprint bouts.

The role of a short post-lunch nap in improving cognitive, motor, and sprint performance in participants with partial sleep deprivation.

Science.gov (United States)

Waterhouse, J; Atkinson, G; Edwards, B; Reilly, T

2007-12-01

The aim of this study was to determine the effects of a post-lunch nap on subjective alertness and performance following partial sleep loss. Ten healthy males (mean age 23.3 years, s = 3.4) either napped or sat quietly from 13:00 to 13:30 h after a night of shortened sleep (sleep 23:00-03:00 h only). Thirty minutes after the afternoon nap or control (no-nap) condition, alertness, short-term memory, intra-aural temperature, heart rate, choice reaction time, grip strength, and times for 2-m and 20-m sprints were recorded. The afternoon nap lowered heart rate and intra-aural temperature. Alertness, sleepiness, short-term memory, and accuracy at the 8-choice reaction time test were improved by napping (P 0.05). Sprint times were improved. Mean time for the 2-m sprints fell from 1.060 s (s(x) = 0.018) to 1.019 s (s(x) = 0.019) (P = 0.031 paired t-test); mean time for the 20-m sprints fell from 3.971 s (s(x) = 0.054) to 3.878 s (s(x) = 0.047) (P = 0.013). These results indicate that a post-lunch nap improves alertness and aspects of mental and physical performance following partial sleep loss, and have implications for athletes with restricted sleep during training or before competition.

Mental skills comparison between elite sprint and endurance track and field runners according to their genetic polymorphism: a pilot study.

Science.gov (United States)

Znazen, Hela; Slimani, Maamer; Miarka, Bianca; Butovskaya, Marina; Siala, Hajer; Messaoud, Taieb; Chamari, Karim; Souissi, Nizar

2017-09-01

Achieving excellence in track and field athletes requires specific mental skills. The aim of the present study was to compare the mental skills between elite sprint and endurance athletes. Forty elite athletes (age 20.55±2.22 years, body mass 74.8±7.9 kg, height 1.70±0.1 m) participated in the present study. The athletes were classified into two groups according to their genetic polymorphism to physical activity: Endurance group (allele I, N.=20) and power group (allele D, N.=20). The mental skills were assessed by means of Ottawa Mental Skill Assessment Tool-3 inventory (OMSAT-3: based in foundation mental skills, psychosomatic skills, and cognitive skills subscales) before the competition period. Furthermore, genetic data were also collected. Sprint and endurance runners were participating in Tunisian National championship. The results showed a significant difference between elite sprint and endurance runners in the foundation mental and psychosomatic skills subscales (all, Pstudy revealed that goal setting, commitment, stress reactions, fear control, imagery, competition planning and mental practice were significantly higher among the elite sprint runners compared to the endurance runners (all, Pstudy could confirm the widely acclaimed research assumption that mental skills, such as goal setting, commitment and mental practice, are the predictor variables of power performances, while endurance performances are associated with different mental skills components. Finally, the results may inform applied practitioners regarding the differences in mental skill demands between power and endurance athletes and the genetic predisposition of practitioners.

Efectos del sistema de pedaleo no circular Q-Ring sobre el rendimiento en el sprint de la disciplina ciclista BMX

Directory of Open Access Journals (Sweden)

M. Mateo

2010-12-01

Full Text Available

El objetivo de este estudio ha sido evaluar los efectos de un sistema de plato no circular de desarrollo variable Q-Ring (Q frente a uno convencional (NQ sobre el rendimiento en el sprint ciclista de Bicicleta de Moto Cross (BMX. Catorce deportistas pertenecientes a la Selección Nacional Española han realizado un test de sprint, desde la rampa de salida, en una pista de BMX (3.95 s de duración; orden randomizado y contrabalanceado. El análisis de contraste prueba T para muestras relacionadas no muestra diferencias estadísticamente significativas para las variables Velocidad media (Vmedia y Tiempo en 31m (T31m entre Q y NQ cuando considera al grupo en su conjunto. Sin embargo, al dividir la muestra entre deportistas Expertos y Noveles, encontramos diferencias a favor de Q respecto de NQ entre los Expertos (Vmedia: 5.91±0.03 vs 5.81±0.05 m/s; T31m: 3.21±0.02 vs 3.23±0.02 s; P < 0.05, diferencias que se traducen hasta en 40 cm de ganancia en los 3.95 primeros segundos de carrera. Estos resultados sugieren que el sistema Q mejora el rendimiento en el sprint de la especialidad ciclista BMX siempre que el deportista posea la capacidad de mover adecuadamente su desarrollo.
Palabras clave: Eficiencia mecánica, plato no circular, pedaleo, rendimiento, sprint, BMX

Quantification of Competitive Game Demands of NCAA Division I College Football Players Using Global Positioning Systems.

Science.gov (United States)

Wellman, Aaron D; Coad, Sam C; Goulet, Grant C; McLellan, Christopher P

2016-01-01

The aim of the present study was to examine the competitive physiological movement demands of National Collegiate Athletic Association (NCAA) Division I college football players using portable global positioning system (GPS) technology during games and to examine positional groups within offensive and defensive teams, to determine if a player's physiological requirements during games are influenced by playing position. Thirty-three NCAA Division I Football Bowl Subdivision football players were monitored using GPS receivers with integrated accelerometers (GPSports) during 12 regular season games throughout the 2014 season. Individual data sets (n = 295) from players were divided into offensive and defensive teams and subsequent position groups. Movement profile characteristics, including total, low-intensity, moderate-intensity, high-intensity, and sprint running distances (m), sprint counts, and acceleration and deceleration efforts, were assessed during games. A one-way ANOVA and post-hoc Bonferroni statistical analysis were used to determine differences in movement profiles between each position group within offensive and defensive teams. For both offensive and defensive teams, significant (p ≤ 0.05) differences exist between positional groups for game physical performance requirements. The results of the present study identified that wide receivers and defensive backs completed significantly (p ≤ 0.05) greater total distance, high-intensity running, sprint distance, and high-intensity acceleration and deceleration efforts than their respective offensive and defensive positional groups. Data from the present study provide novel quantification of position-specific physical demands of college football games and support the use of position-specific training in the preparation of NCAA Division I college football players for competition.

Intensive Versus Standard Blood Pressure Control in SPRINT-Eligible Participants of ACCORD-BP.

Science.gov (United States)

Buckley, Leo F; Dixon, Dave L; Wohlford, George F; Wijesinghe, Dayanjan S; Baker, William L; Van Tassell, Benjamin W

2017-12-01

We sought to determine the effect of intensive blood pressure (BP) control on cardiovascular outcomes in participants with type 2 diabetes mellitus (T2DM) and additional risk factors for cardiovascular disease (CVD). This study was a post hoc, multivariate, subgroup analysis of ACCORD-BP (Action to Control Cardiovascular Risk in Diabetes Blood Pressure) participants. Participants were eligible for the analysis if they were in the standard glucose control arm of ACCORD-BP and also had the additional CVD risk factors required for SPRINT (Systolic Blood Pressure Intervention Trial) eligibility. We used a Cox proportional hazards regression model to compare the effect of intensive versus standard BP control on CVD outcomes. The "SPRINT-eligible" ACCORD-BP participants were pooled with SPRINT participants to determine whether the effects of intensive BP control interacted with T2DM. The mean baseline Framingham 10-year CVD risk scores were 14.5% and 14.8%, respectively, in the intensive and standard BP control groups. The mean achieved systolic BP values were 120 and 134 mmHg in the intensive and standard BP control groups ( P control reduced the composite of CVD death, nonfatal myocardial infarction (MI), nonfatal stroke, any revascularization, and heart failure (hazard ratio 0.79; 95% CI 0.65-0.96; P = 0.02). Intensive BP control also reduced CVD death, nonfatal MI, and nonfatal stroke (hazard ratio 0.69; 95% CI 0.51-0.93; P = 0.01). Treatment-related adverse events occurred more frequently in participants receiving intensive BP control (4.1% vs. 2.1%; P = 0.003). The effect of intensive BP control on CVD outcomes did not differ between patients with and without T2DM ( P > 0.62). Intensive BP control reduced CVD outcomes in a cohort of participants with T2DM and additional CVD risk factors. © 2017 by the American Diabetes Association.

Muscle variables of importance for physiological performance in competitive football

DEFF Research Database (Denmark)

Mohr, Magni; Thomassen, Martin; Girard, Olivier

2016-01-01

PURPOSE: To examine how match performance parameters in trained footballers relate to skeletal muscle parameters, sprint ability and intermittent exercise performance. METHODS: 19 male elite football players completed an experimental game with physical performance determined by video analysis...... and exercise capacity assessed by intermittent Yo-Yo IR1 and IR2 tests, and a repeated sprint test (RST). Muscle tissue was obtained for analysis of metabolic enzyme maximal activity and key muscle protein expression. RESULTS: Total game distance, distance deficit from first to second half and high......-intensity running in the final 15 min of the game were all correlated to the players' Yo-Yo IR1 performance (r = 0.55-0.87) and beta-hydroxyacyl-CoA-dehydrogenase (HAD) maximal activity (r = 0.55-0.65). Furthermore, platelet/endothelial cell adhesion molecule-1 (PECAM1) protein expression was weakly (r = 0...

Comparison of speech perception performance between Sprint/Esprit 3G and Freedom processors in children implanted with nucleus cochlear implants.

Science.gov (United States)

Santarelli, Rosamaria; Magnavita, Vincenzo; De Filippi, Roberta; Ventura, Laura; Genovese, Elisabetta; Arslan, Edoardo

2009-04-01

To compare speech perception performance in children fitted with previous generation Nucleus sound processor, Sprint or Esprit 3G, and the Freedom, the most recently released system from the Cochlear Corporation that features a larger input dynamic range. Prospective intrasubject comparative study. University Medical Center. Seventeen prelingually deafened children who had received the Nucleus 24 cochlear implant and used the Sprint or Esprit 3G sound processor. Cochlear implantation with Cochlear device. Speech perception was evaluated at baseline (Sprint, n = 11; Esprit 3G, n = 6) and after 1 month's experience with the Freedom sound processor. Identification and recognition of disyllabic words and identification of vowels were performed via recorded voice in quiet (70 dB [A]), in the presence of background noise at various levels of signal-to-noise ratio (+10, +5, 0, -5) and at a soft presentation level (60 dB [A]). Consonant identification and recognition of disyllabic words, trisyllabic words, and sentences were evaluated in live voice. Frequency discrimination was measured in a subset of subjects (n = 5) by using an adaptive, 3-interval, 3-alternative, forced-choice procedure. Identification of disyllabic words administered at a soft presentation level showed a significant increase when switching to the Freedom compared with the previously worn processor in children using the Sprint or Esprit 3G. Identification and recognition of disyllabic words in the presence of background noise as well as consonant identification and sentence recognition increased significantly for the Freedom compared with the previously worn device only in children fitted with the Sprint. Frequency discrimination was significantly better when switching to the Freedom compared with the previously worn processor. Serial comparisons revealed that that speech perception performance evaluated in children aged 5 to 15 years was superior with the Freedom than previous generations of Nucleus

Isometric strength, sprint power, and aerobic power in individuals with a spinal cord injury

NARCIS (Netherlands)

Janssen, T W; van Oers, C A; Hollander, A P; Veeger, DirkJan (H. E. J.); van der Woude, L H

This study investigated in rather specific wheelchair tests the relationships among estimates of isometric upper-body strength (Fiso), sprint power (P30), aerobic power (VO2peak), and maximal power output (POaer) in a group of 44 men (age 34 +/- 12 yr) with longstanding spinal cord injuries ranging

Precision Medicine for Hypertension Management in Chronic Kidney Disease: Relevance of SPRINT for Therapeutic Targets in Nondiabetic Renal Disease.

Science.gov (United States)

Ruzicka, Marcel; Burns, Kevin D; Hiremath, Swapnil

2017-05-01

In this review we evaluate the literature to determine if lower blood pressure (BP) targets are beneficial for patients with nondiabetic chronic kidney disease (CKD). Modification of Diet in Renal Disease (MDRD), African American Study of Kidney Disease and Hypertension (AASK), and Ramipril Efficacy in Nephropathy-2 (REIN-2), designed to assess the benefit of lower BP on progression of nondiabetic CKD, generally came to the same negative conclusion. They were not designed and powered to assess an effect of lower BP on cardiovascular outcomes. The Systolic Blood Pressure Intervention Trial (SPRINT) was the first trial designed and powered to address this issue, and showed a clear benefit of a lower targeted and achieved BP. SPRINT did not show any renal benefits from lower BP, and it was not designed to assess this outcome, and it enrolled patients with less "renal risk" per se. A distinguishing feature of SPRINT compared with other large trials is that it highlighted the importance of precise BP measurement methods in defining targets in hypertension treatment. Accordingly, we propose that SPRINT is truly a "game-changing" clinical trial that sets the bar for management of hypertension in select patients with nondiabetic CKD. In these patients, systolic BP target depends critically on the BP measurement method: < 140 mm Hg when derived from 3 readings using a mercury sphygmomanometer after 5 minutes of rest, < 130 mm Hg when calculated from at a minimum of 3 readings using an automated oscillometric device, and < 120 mm Hg when taken using an automated oscillometric device after 5 minutes of unattended rest. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

High accuracy subwavelength distance measurements: A variable-angle standing-wave total-internal-reflection optical microscope

International Nuclear Information System (INIS)

Haynie, A.; Min, T.-J.; Luan, L.; Mu, W.; Ketterson, J. B.

2009-01-01

We describe an extension of the total-internal-reflection microscopy technique that permits direct in-plane distance measurements with high accuracy (<10 nm) over a wide range of separations. This high position accuracy arises from the creation of a standing evanescent wave and the ability to sweep the nodal positions (intensity minima of the standing wave) in a controlled manner via both the incident angle and the relative phase of the incoming laser beams. Some control over the vertical resolution is available through the ability to scan the incoming angle and with it the evanescent penetration depth.

Relationships between Sprint, Jumping and Strength Abilities, and 800 M Performance in Male Athletes of National and International Levels.

Science.gov (United States)

Bachero-Mena, Beatriz; Pareja-Blanco, Fernando; Rodríguez-Rosell, David; Yáñez-García, Juan Manuel; Mora-Custodio, Ricardo; González-Badillo, Juan José

2017-09-01

This study analysed the relationships between sprinting, jumping and strength abilities, with regard to 800 m running performance. Fourteen athletes of national and international levels in 800 m (personal best: 1:43-1:58 min:ss) completed sprint tests (20 m and 200 m), a countermovement jump, jump squat and full squat test as well as an 800 m race. Significant relationships (p relationship between the first to the last 50 m interval times and the 800 m time tended to increase (1st 50 m: r = 0.71; 2nd 50 m: r = 0.72; 3rd 50 m: r = 0.81; 4th 50 m: r = 0.85). Performance in 800 m also correlated significantly (p < 0.01-0.05) with strength variables: the countermovement jump (r = -0.69), jump squat (r = -0.65), and full squat test (r = -0.58). Performance of 800 m in high-level athletes was related to sprint, strength and jumping abilities, with 200 m and the latest 50 m of the 200 m being the variables that most explained the variance of the 800 m performance.

The force, power and energy of the 100 meter sprint

OpenAIRE

Helene, O.; Yamashita, M. T.

2009-01-01

At the 2008 Summer Olympics in Beijing, Usain Bolt broke the world record for the 100 m sprint. Just one year later, at the 2009 World Championships in Athletics in Berlin he broke it again. A few months after Beijing, Eriksen [Am. J. Phys. 77, 224-228 (2009)] studied Bolt's performance and predicted that Bolt could have run about one-tenth of a second faster, which was confirmed in Berlin. In this paper we extend the analysis of Eriksen to model Bolt's velocity time dependence for the Beijin...

Advancing hypoxic training in team sports: from intermittent hypoxic training to repeated sprint training in hypoxia.

Science.gov (United States)

Faiss, Raphaël; Girard, Olivier; Millet, Grégoire P

2013-12-01

Over the past two decades, intermittent hypoxic training (IHT), that is, a method where athletes live at or near sea level but train under hypoxic conditions, has gained unprecedented popularity. By adding the stress of hypoxia during 'aerobic' or 'anaerobic' interval training, it is believed that IHT would potentiate greater performance improvements compared to similar training at sea level. A thorough analysis of studies including IHT, however, leads to strikingly poor benefits for sea-level performance improvement, compared to the same training method performed in normoxia. Despite the positive molecular adaptations observed after various IHT modalities, the characteristics of optimal training stimulus in hypoxia are still unclear and their functional translation in terms of whole-body performance enhancement is minimal. To overcome some of the inherent limitations of IHT (lower training stimulus due to hypoxia), recent studies have successfully investigated a new training method based on the repetition of short (<30 s) 'all-out' sprints with incomplete recoveries in hypoxia, the so-called repeated sprint training in hypoxia (RSH). The aims of the present review are therefore threefold: first, to summarise the main mechanisms for interval training and repeated sprint training in normoxia. Second, to critically analyse the results of the studies involving high-intensity exercises performed in hypoxia for sea-level performance enhancement by differentiating IHT and RSH. Third, to discuss the potential mechanisms underpinning the effectiveness of those methods, and their inherent limitations, along with the new research avenues surrounding this topic.

Acute effects of two different initial heart rates on testing the Repeated Sprint Ability in young soccer players.

Science.gov (United States)

Ruscello, B; Briotti, G; Tozzo, N; Partipilo, F; Taraborelli, M; Zeppetella, A; Padulo, J; D'Ottavio, S

2015-10-01

The aim of this paper was to investigate the acute effects of two different initial heart rates intensities when testing the repeated sprint ability (RSA) performances in young soccer players. Since there are many kinds of pre-match warm-ups, we chose to take as an absolute indicator of internal load the heart rate reached at the end of two different warm-up protocols (60 vs. 90% HRmax) and to compare the respective RSA performances. The RSA tests were performed on fifteen male soccer players (age: 17.9±1.5 years) with two sets of ten shuttle-sprints (15+15 m) with a 1:3 exercise to rest ratio, in different days (randomized order) with different HR% (60 & 90% HRmax). In order to compare the different sprint performances a Fatigue Index (FI%) was computed, while the blood lactate concentrations (BLa-) were measured before and after testing, to compare metabolic demand. Significant differences among trials within each sets (Psoccer player operates during a real match. This background may be partially reproduced by warming up protocols that, by duration and metabolic commitment, can reproduce conveniently the physiological conditions encountered in a real game (e.g. HRmax≈85-95%; BLa->4 mmol/L(-1)).

EL EFECTO DE LA SOBRECARGA CON CREATINA EN EL RENDIMIENTO F͍SICO EN SPRINT DE ATLETISMO, POSTERIOR A UN PROTOCOLO DE EJERCICIO INTERMITENTE Y PROLONGADO

Directory of Open Access Journals (Sweden)

Óscar Pablo Gutiérrez Sancho

2006-12-01

Full Text Available El estudio examina el efecto de la sobrecarga con Creatina (Cr sobre el rendimiento en 6 sprints (200m de atletismo realizados a máxima intensidad, después de haber ocasionado la fatiga (+ 1hr con ejercicio de carrera submáximo (60-85% de FCmáx. En un diseño de medidas repetidas y contrabalanceado 6 hombres activos pasaron por tres condiciones experimentales: condición control (CT; condición con creatina (CCr; y condición placebo (PL. En la condición CT no recibieron ningún tratamiento. En la condición CCr recibieron monohidrato de creatina (12 gr x d x 7 d, dividido en 2 dosis diarias. De igual dosis y duración se suministró un carbohidrato para la condición PL. Se registró el tiempo en cada sprint de las diferentes condiciones y seguidamente se utilizó una ANOVA de dos vías (condiciones x número de sprint para mediciones pareadas. El análisis estadístico identificó una interacción significativa (p < 0.05, posteriormente un análisis de seguimiento mostró que las condiciones CT y CCr ocasionaban la interacción (p < 0.05. Un segundo análisis de efecto simple indico diferencias significativas (p < 0.05, en todos los sprints. El post hoc de Tukey evidenció que las condiciones (CCr, PL, eran siempre diferentes a la condición CT, no así entre ellas. Excepto en el sprint 1: CT ( = 37.03 ± .77 s y CCr ( = 35.87 ± .99 s (p < 0.05; y entre CCr ( = 35.87 ± .99 s y PL ( = 36.72 ± .54 s. Hubo efectos simples de los tratamientos sobre el tiempo promedio (p= .001 y del número de sprint (p= .000, pero no fueron confirmados por la interacción. En conclusión hubo una mejora clara en la condición CCr solo en el primer sprint 1, y una tendencia a retardar la fatiga con la condición

Repeated Sprint Ability in Young Basketball Players (Part 2): The Chronic Effects of Multidirection and of One Change of Direction Are Comparable in Terms of Physiological and Performance Responses.

Science.gov (United States)

Attene, Giuseppe; Nikolaidis, Pantelis T; Bragazzi, Nicola L; Dello Iacono, Antonio; Pizzolato, Fabio; Zagatto, Alessandro M; Dal Pupo, Juliano; Oggianu, Marcello; Migliaccio, Gian M; Mannucci Pacini, Elena; Padulo, Johnny

2016-01-01

The aim of this study was to examine the effects of a 5-week training program, consisting of repeated 30-m sprints, on two repeated sprint ability (RSA) test formats: one with one change of direction (RSA) and the other with multiple changes of direction (RSM). Thirty-six young male and female basketball players (age 16.1 ± 0.9 years), divided into two experimental groups, were tested for RSA, RSM, squat jump, counter-movement jump, and the Yo-Yo Intermittent Recovery-Level-1 (Yo-Yo IR1) test, before and after a 4-week training program and 1 week of tapering. One group performed 30-m sprints with one change of direction (RSA group, RSAG), whereas the other group performed multidirectional 30-m sprints (RSM group, RSMG). Both groups improved in all scores in the post-intervention measurements (P basketball players, but have a different psycho-physiological impact.

A Modified T-Test for Football Referees to Test Agility, Quickness and Sprint Performances

Science.gov (United States)

Muniroglu, S.; Subak, E.

2018-01-01

The football referees perform many actions as jogging, running, sprinting, side steps and backward steps during a football match. Further, the football referees change match activities every 5-6 seconds. Many tests are being conducted to determine the physical levels and competences of football referees like 50 m running, 200 m running, 12 minutes…

The physiological stress response to high-intensity sprint exercise following the ingestion of sodium bicarbonate.

Science.gov (United States)

Peart, Daniel J; Kirk, Richard J; Hillman, Angela R; Madden, Leigh A; Siegler, Jason C; Vince, Rebecca V

2013-01-01

The purpose of this study was to investigate the effects of pre-exercise alkalosis on the physiological stress response to high-intensity exercise. Seven physically active males (age 22 ± 3 years, height 1.82 ± 0.06 m, mass 81.3 ± 8.4 kg and peak power output 300 ± 22 W) performed a repeated sprint cycle exercise following a dose of 0.3 g kg(-1) body mass of sodium bicarbonate (NaHCO(3)) (BICARB), or a placebo of 0.045 g kg(-1) body mass of sodium chloride (PLAC). Monocyte-expressed heat shock protein 72 (HSP72) and plasma thiobarbituric acid reactive substances (TBARS) were significantly attenuated in BICARB compared to PLAC (p = 0.04 and p = 0.039, respectively), however total anti-oxidant capacity, the ratio of oxidised to total glutathione, cortisol, interleukin 6 and interleukin 8 were not significantly induced by the exercise. In conclusion, monocyte-expressed HSP72 is significantly increased following high-intensity anaerobic exercise, and its attenuation following such exercise with the ingestion of NaHCO(3) is unlikely to be due to a decreased oxidative stress.

Fatigue and changes of ATP, creatine phosphate, and lactate during the 400-m sprint.

Science.gov (United States)

Hirvonen, J; Nummela, A; Rusko, H; Rehunen, S; Härkönen, M

1992-06-01

Fatigue during the 400-m sprint was studied by measuring muscle ATP, creatine phosphate (CP), lactate (M-La), and blood lactate (B-La) in six male runners before and after four experimental sprints (100, 200, 300, and 400 m). During the first 100 m, muscle CP decreased from 15.8 +/- 1.7 to 8.3 +/- 0.3 mmol/kg while M-La increased to 3.6 +/- 0.4 mmol/kg. After 200 m the CP had decreased to 6.5 +/- 0.5 mmol/kg and M-La had increased to 8.3 +/- 1.1 mmol/kg. At the end of the 400 meters, ATP and CP concentrations had decreased by 27% and 89%, respectively, and M-La had increased to 17.3 +/- 0.9 mmol/kg. It was concluded that after 200 m the speed of running decreased, although CP was not depleted and lactate concentration was not at maximum level. Complete fatigue occurred when CP stores were depleted and B-La and M-La attained an individual maximum.

Distance and total column density to the periodic radio star LSI + 61 deg 303

International Nuclear Information System (INIS)

Frail, D.A.; Hjellming, R.M.

1991-01-01

New observations toward the periodic radio star LSI + 61 deg 303 in the lines of H I at 21 cm and CO-18 at 2.7 mm are reported. Using the kinematic method, H I observations are interpreted in terms of the two-armed spiral shock model of Roberts (1972) to derive a distance to LSI + 61 deg 303 of 2.0 + or - 0.2 kpc. The results clearly show the presence of the Perseus arm shock and locate LSI + 61 deg 303 between this shock and the more distant postshock gas. In addition, by using the H I and CO-18 data, the total neutral and molecular gas column density is derived along the line of sight toward LSI + 61 deg 303. 32 refs

The effects of a single whole body cryotherapy exposure on physiological, performance and perceptual responses of professional academy soccer players following repeated sprint exercise

OpenAIRE

Russell, Mark; Birch, Jack; Love, Thomas; Cook, Christian; Bracken, Richard M.; Taylor, Tom; Swift, Eamon; Cockburn, Emma; Finn, Charlie; Cunningham, Daniel; Wilson, Laura; Kilduff, Liam P.

2017-01-01

In professional youth soccer players, the physiological, performance and perceptual effects of a single whole body cryotherapy (WBC) session performed shortly after repeated sprint exercise were investigated. In a randomized, counter-balanced and crossover design, 14 habituated English Premier League academy soccer players performed 15 x 30 m sprints (each followed by a 10 m forced deceleration) on two occasions. Within 20 min of exercise cessation, players entered a WBC chamber (Cryo: 30 s a...

Comparison of muscle strength, sprint power and aerobic capacity in adults with and without cerebral palsy

NARCIS (Netherlands)

de Groot, Sonja; Dallmeijer, Annet J.; Bessems, Paul J. C.; Lamberts, Marcel L.; van der Woude, Lucas H. V.; Janssen, Thomas W. J.

Objective: To compare: (i) muscle strength, sprint power and maximal aerobic capacity; and (ii) the correlations between these variables in adults with and without cerebral palsy. Design: Cross-sectional study. Subjects: Twenty adults with and 24 without cerebral palsy. Methods: Isometric and

Comparison of muscle strength, sprint power and aerobic capacity in adults with and without cerebral palsy

NARCIS (Netherlands)

de Groot, S.; Dallmeijer, A.J.; Bessems, P.J.C.; Lamberts, M.L.; van der Woude, L.H.V.; Janssen, T.W.J.

2012-01-01

Objective: To compare: (i) muscle strength, sprint power and maximal aerobic capacity; and (ii) the correlations between these variables in adults with and without cerebral palsy. Design: Cross-sectional study. Subjects: Twenty adults with and 24 without cerebral palsy. Methods: Isometric and

Maturation-related adaptations in running speed in response to sprint training in youth soccer players.

Science.gov (United States)

Moran, Jason; Parry, Dave A; Lewis, Ieuan; Collison, Jay; Rumpf, Michael C; Sandercock, Gavin R H

2018-05-01

This study investigated the effects of a previously recommended dose of sprint training (ST) in young male soccer players of differing maturity status. Quasi-experimental design. Male soccer players from two professional academies were divided into Pre-PHV (Training: n=12; Control: n=13) and Mid-PHV (Training: n=7; Control=10) groups. The training groups completed 16 sprints of 20m with 90s recovery, once per week for 8weeks. Between-group effect sizes (ES) were substantially larger in Pre-PHV (10m [1.54, CI: 0.74-2.23]; 20m [1.49, CI: 0.75-2.23]; 5-10-5 [0.92, CI: 0.23-1.61]) than in Mid-PHV (10m [-0.00, CI: -0.81 to 0.81]; 20m [-0.12, CI: -0.93 to 0.69]; 5-10-5 [-0.41, CI: -1.22 to 0.41]). Within-group effects demonstrated a similar, though less accentuated, trend which revealed ST to be effective in both Pre-PHV (10m [0.44, CI: -0.24 to 1.12]; 20m [0.45, CI: -0.23 to 1.13]; 5-10-5 [0.69, CI: 0.00-1.38]) and Mid-PHV (10m [0.51, CI: -0.38 to 1.40]; 20m [0.33, CI: -0.56 to 1.21]; 5-10-5 [0.43, CI: -0.46 to 1.32]). ST, in the amount of 16 sprints over 20m with a 90s rest, may be more effective in Pre-PHV youths than in Mid-PHV youths. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Relationship between the Handball-Specific Complex-Test and Intermittent Field Test performance in professional players.

Science.gov (United States)

Hermassi, Souhail; Hoffmeyer, Birgit; Irlenbusch, Lars; Fieseler, Georg; Noack, Frank; Delank, Karl-Stefan; Gabbett, Tim J; Souhaiel Chelly, Mohamed; Schwesig, René

2018-01-01

We investigated the relationship between the Handball Complex-Test (HBCT) and two selected field performance tests (the repeated sprint ability [RSA], and the Yo-Yo Intermittent Recovery Test) in elite handball players. Nineteen handball players (age: 25.7±5.1 years) were drawn from the First Professional German League. The HBCT consists of four activity series (AS): agility parcours, defensive action, sprint (10 m, 20 m) and throw-on-goal parcours; these activities were completed twice, with five active pauses of 30-35 s, and a follow-up of recovery over the subsequent 10 minutes. The RSA comprised 6 x (15+15 m) sprints starting every 20 s; scoring noted best time (RSAbest), total time (RSATT) and decrement (RSAdec). In the Yo-Yo Intermittent Recover, we recorded the total distance covered (TD). Heart rates (HR) were recorded throughout and recovery was assessed for measurements immediately post-test (R0) and 10 minutes after completing the test (R10). A strong correlation was found between HBCT and fastest 10 m and 20 m RSA sprint times (r=0.811, r=0.815, respectively). Also, the HBCT total 10 m and 20 m sprint times showed a strong positive association with RSATT (r=0.70; r=0.63, respectively), and the RSA heart rate post-test was strongly correlated with the HBCT heart rate after round two (r=0.865). Data from the match-specific HBCT Test shows a strong positive association with other more generic intermittent field test measurements. These observations support the validity of using the generic tests to monitor current fitness and responses to training in team handball players.

The Relationship between Repeated Sprint Performance and Velocity Values during Loaded-Squat Jump Exercise

Science.gov (United States)

Can, Ibrahim; Sadik, Seda; Bayrakdaroglu, Serdar

2018-01-01

The purpose of this study is to investigate the relationship between repeated sprint performance and velocity values during loaded-squat jump exercise. In accordance with this purpose, 23 kickboxing athletes (age: 21,1 ± 2,10 years; height: 178,7 ± 5,01 cm; weight: 70,8 ± 7,85 kg) participated voluntarily in this study. Participants were performed…

Effect of a typical in-season week on strength jump and sprint performances in national-level female basketball players.

Science.gov (United States)

Delextrat, A; Trochym, E; Calleja-González, J

2012-04-01

The aim of this study was to investigate the effect of a typical in-season week including four practice sessions and one competitive game on strength, jump and sprint performances in national-level female basketball players. Nine female basketball players (24.3±4.1 years old, 173.0±7.9 cm, 65.1±10.9 kg, 21.1±3.8% body fat) participated in ten testing sessions, before and immediately after practices and game (five pre- and five post-tests). Each session involved isokinetic peak torque measurements of the quadriceps and hamstrings of the dominant leg at 60º.s-1, countermovement jump (CMJ) and 20-m sprint. Fluid loss and subjective training load were measured during each practice session, while the frequencies of the main movements performed during the game were recorded. A two-way ANOVA was used to asses the effect of each practice/game and the effect of the day of the week on performances, and the relationship between performance variations and variables recorded during practices/game were analyzed by a Pearson correlation coefficient. Individual sessions induced significant decreases in lower limb strength (from 4.6 to 10.9%, Pjump ability, and monitor the recovery of their players' strength, sprint and jump capacities following specific sessions.

Sprint mechanics return to competition follow-up after hamstring injury on a professional soccer player: A case study with an inertial sensor unit based methodological approach.

Science.gov (United States)

Setuain, Igor; Lecumberri, Pablo; Izquierdo, Mikel

2017-10-03

The present research aimed to describe an inertial unit (IU)-based sprint mechanics evaluation model for assessing players' readiness to return to competition after suffering a grade I hamstring injury. A professional male football player (age 19years; height 177cm; weight 70kg, midfielder, Spanish, 3° Division) with a grade 1 biceps femoris injury was evaluated at pre-season, at return to play after injury and at the end of the competitive season. Sprint mechanics were analyzed via the use of an inertial orientation tracker (Xsens Technologies B.V. Enschede, Netherlands) attached over the L3-L4 region of the subject's lumbar spine. Sprint mechanics such as horizontal components of ground reaction force were assessed in both legs during sprinting actions. Findings and interpretation: Both the coefficient of the horizontal force application (SFV) and the ratio of forces (DRF) applied at increasing velocity were decreased in the injured limb compared with the contralateral healthy limb at the return to play evaluation (73% and 76% reductions, respectively) and returned to symmetrical levels at the end-season evaluation. Copyright © 2017 Elsevier Ltd. All rights reserved.

The relationship between muscle strength, anaerobic performance, agility, sprint ability and vertical jump performance in professional basketball players.

Science.gov (United States)

Alemdaroğlu, Utku

2012-03-01

The purpose of this study was to investigate the relationship between isokinetic knee strength, anaerobic performance, sprinting ability, agility and vertical jump performance in first division basketball players. Twelve male first division basketball players participated in this study. The mean age was 25.1 ± 1.7 yrs; mean body height 194.8 ± 5.7 cm; mean body mass 92.3± 9.8 kg; mean PBF 10.1± 5.1; and mean VO2max 50.55 ± 6.7 ml/kg/min Quadriceps and hamstrings were measured at 60° and 180°/s, anaerobic performance was evaluated using the Wingate anaerobic power test, sprint ability was determined by single sprint performance (10-30 m), jump performance was evaluated by countermovement (CMJ) and squat jump (SJ) tests and agility performance was measured using the T drill agility test. Quadriceps strength was significantly correlated with peak power at all contraction velocities. However, for mean power, significant correlation was only found between the 60° left and 180° right knee quadriceps measurements. No measure of strength was significantly related to the measurements from/results of field tests. Moreover, strong relations were found between the performance of athletes in different field tests (p< 0.05). The use of correlation analysis is the limitation of the this study.

Acute responses of circulating microRNAs to low-volume sprint interval cycling

Directory of Open Access Journals (Sweden)

Shu Fang eCui

2015-10-01

Full Text Available Low-volume high-intensity interval training is an efficient and practical method of inducing physiological responses in various tissues to develop physical fitness and may also change the expression of circulating microRNAs (miRNAs. The purpose of the present study was to examine whether miRNAs for muscle, heart, somatic tissue and metabolism were affected by 30-s intervals of intensive sprint cycling. We also examined the relationship of these miRNAs to conventional biochemical and performance indices. Eighteen healthy young males performed sprint interval cycling. Circulating miRNAs in plasma were detected using TaqMan-based quantitative PCR and normalized to Let-7d/g/i. In addition, we determined the levels of insulin-like growth factor-I, testosterone and cortisol, and anaerobic capacity. Compared to plasma levels before exercise muscle-specific miR-1 (0.12 ± 0.02 vs. 0.09 ± 0.02, miR-133a (0.46 ± 0.10 vs. 0.31 ± 0.06 and miR-133b (0.19 ± 0.02 vs. 0.10 ± 0.01 decreased (all P < 0.05, while miR-206 and miR-499 remained unchanged. The levels of metabolism related miR-122 (0.62 ± 0.07 vs. 0.34 ± 0.03 and somatic tissues related miR-16 (1.74 ± 0.27 vs. 0.94 ± 0.12 also decreased (both P < 0.05. The post-exercise IGF-1 and cortisol concentrations were significantly increased, while testosterone concentrations did not. Plasma levels of miR-133b correlated to peak power (r = 0.712, P = 0.001 and miR-122 correlated to peak power ratio (r = 0.665, P = 0.003. In conclusion sprint exercise provokes genetic changes for RNA related to specific muscle or metabolism related miRNAs suggesting that miR-133b and miR-122 may be potential useful biomarkers for actual physiological strain or anaerobic capacity. Together, our findings on the circulating miRNAs may provide new insight into the physiological responses that are being performed during exercise and delineate mechanisms by which exercise confers distinct phenotypes and improves performance.

Cold water immersion recovery following intermittent-sprint exercise in the heat.

Science.gov (United States)

Pointon, Monique; Duffield, Rob; Cannon, Jack; Marino, Frank E

2012-07-01

This study examined the effects of cold water immersion (CWI) on recovery of neuromuscular function following simulated team-sport exercise in the heat. Ten male team-sport athletes performed two sessions of a 2 × 30-min intermittent-sprint exercise (ISE) in 32°C and 52% humidity, followed by a 20-min CWI intervention or passive recovery (CONT) in a randomized, crossover design. The ISE involved a 15-m sprint every minute separated by bouts of hard running, jogging and walking. Voluntary and evoked neuromuscular function, ratings of perceived muscle soreness (MS) and blood markers for muscle damage were measured pre- and post-exercise, immediately post-recovery, 2-h and 24-h post-recovery. Measures of core temperature (Tcore), heart rate (HR), capillary blood and perceptions of exertion, thermal strain and thirst were also recorded at the aforementioned time points. Post-exercise maximal voluntary contraction (MVC) and activation (VA) were reduced in both conditions and remained below pre-exercise values for the 24-h recovery (P recovery period (P recovery rate of reduction in Tcore, HR and MS was enhanced with CWI whilst increasing MVC and VA (P recovery MVC and activation were significantly higher in CONT compared to CWI (P = 0.05). Following exercise in the heat, CWI accelerated the reduction in thermal and cardiovascular load, and improved MVC alongside increased central activation immediately and 2-h post-recovery. However, despite improved acute recovery CWI resulted in an attenuated MVC 24-h post-recovery.

What is the Safest Sprint Starting Position for American Football Players?

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Bruno Bonnechere, Benoit Beyer, Marcel Rooze, Jan Serge Van Sint

2014-06-01

Full Text Available The main objective of this study was to perform a biomechanical analysis of three different sprint start patterns to determine the safest position in term of neck injury and Sport-Related Concussion (SRC. The second objective was to collect data on the learning process effect between football players and non-players. Three different sprint initial positions adopted by football players were studied (i.e., 4-, 3- and 2-point positions. Twenty five young healthy males, including 12 football players, participated to this study. A stereophotogrammetric system (i.e., Vicon was used to record motion patterns and body segments positions. Various measurements related to head and trunk orientation, and player field-of-view were obtained (e.g., head height, trunk bending, time to reach upright position, head speed (vertical direction and body speed (horizontal direction. Learning process was found to have no influence on studied parameters. Head redress is also delayed when adopting a 4-point position leading to a reduce field-of-view during the start and increasing therefore the probability of collision. Concerning the three different positions, the 4-point position seems to be the more dangerous because leading to higher kinetic energy than the 2- and 3-point start positions. This study proposes a first biomechanical approach to understand risk/benefit balance for athletes for those three different start positions. Results suggested that the 4-point position is the most risky for football players.

Sprinting performance and resistance based training interventions: A systematic review with meta-analysis

OpenAIRE

Bolger, Richard; Kenny, Ian; Lyons, Mark; Harrison, Andrew J.

2014-01-01

peer-reviewed Introduction Much of the research which focuses on improving sprinting performance has been carried out with team sport athletes or endurance athletes (Berryman, Maurel, & Bosquet, 2010; Esteve-Lanao, Rhea, Fleck, & Lucia, 2008; Hanon, Bernard, Rabate, & Claire, 2012; Rhea, Kenn, & Dermody, 2009; Shalfawi, Haugen, Jakobsen, Enoksen, & T??nnessen, 2013; West et al., 2013). There is little consensus with the prescription of resistance based training within this body of resea...

Validity of the Pediatric Running-Based Anaerobic Sprint Test to Determine Anaerobic Performance in Healthy Children

NARCIS (Netherlands)

Bongers, Bart C.; Werkman, Maarten S.; Blokland, Donna; Eijsermans, Maria J. C.; van der Torre, Patrick; Bartels, Bart; Verschuren, Olaf; Takken, Tim

Purpose: To determine criterion validity of the pediatric running-based anaerobic sprint test (RAST) as a nonsophisticated field test for evaluating anaerobic performance in healthy children and adolescents. Methods: Data from 65. healthy children (28 boys and 37 girls between 6 and 18 years of age,

Dietary Acid-Base Balance in Adolescent Sprint Athletes: A Follow-up Study

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Peter Clarys

2011-02-01

Full Text Available Sprinters are advised to include additional protein sources in their diet. Basal metabolism and vigorous physical activities generate hydrogen ions that need to be buffered. The present follow-up study estimates the dietary potential renal acid load (PRAL and net endogenous acid production (NEAP in adolescent sprint athletes. Seven-day food diaries and anthropometrics of 60 adolescent sprint athletes (mean age at start 14.7 ± 1.9 years were collected every six months over a three year period. Comparisons were made between athletes with a negative (PRAL(− versus positive PRAL (PRAL(+. For the entire sample, mean PRAL values of up to 6 mEq/day were slightly positive despite a relatively high protein intake of around 1.5 g/kg. The NEAP ranging between 42 and 46 mEq/day remained stable during the study period. Athletes with a PRAL(− (−8 to −10 mEq/day consumed significantly more fruit and fruit juice than athletes with a PRAL(+ (+9 to 14 mEq/day. Athletes with a PRAL(+ did not consume more meat, fish and poultry than athletes with a PRAL(−. Grains and dairy products were only discriminative between the two groups on one measurement occasion. Lowering the PRAL can be obtained by increasing the consumption of potatoes, fruits, vegetables and vegetable soup.

EFFECTS OF COMBINED FOOT/ANKLE ELECTROMYOSTIMULATION AND RESISTANCE TRAINING ON THE IN-SHOE PLANTAR PRESSURE PATTERNS DURING SPRINT IN YOUNG ATHLETES

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François Fourchet

2011-06-01

Full Text Available Several studies have already reported that specific foot/ankle muscle reinforcement strategies induced strength and joint position sense performance enhancement. Nevertheless the effects of such protocols on sprint performance and plantar loading distribution have not been addressed yet. The objective of the study is to investigate the influence of a 5-wk foot/ankle strength training program on plantar loading characteristics during sprinting in adolescent males. Sixteen adolescent male athletes of a national training academy were randomly assigned to either a combined foot/ankle electromyostimulation and resistance training (FAST or a control (C group. FAST consisted of foot medial arch and extrinsic ankle muscles reinforcement exercises, whereas C maintained their usual training routine. Before and after training, in-shoe loading patterns were measured during 30-m running sprints using pressure sensitive insoles (right foot and divided into nine regions for analysis. Although sprint times remained unchanged in both groups from pre- to post- training (3.90 ± 0.32 vs. 3.98 ± 0.46 s in FAST and 3.83 ± 0.42 vs. 3.81 ± 0.44 s in C, changes in force and pressure appeared from heel to forefoot between FAST and C. In FAST, mean pressure and force increased in the lateral heel area from pre- to post- training (67.1 ± 44.1 vs. 82.9 ± 28.6 kPa [p = 0.06]; 25.5 ± 17.8 vs. 34.1 ± 14.3 N [p = 0.05] and did not change in the medial forefoot (151.0 ± 23.2 vs. 146.1 ± 30.0 kPa; 142.1 ± 29.4 vs. 136.0 ± 33.8; NS. Mean area increased in FAST under the lateral heel from pre- to post- (4.5 ± 1.3 vs. 5.7 ± 1.6 cm2 [p < 0.05] and remained unchanged in C (5.5 ± 2.8 vs. 5.0 ± 3.0 cm2. FAST program induced significant promising lateral and unwanted posterior transfer of the plantar loads without affecting significantly sprinting performance

PROGNOSTIC QUALITY OF MOTOR AND MORPHOLOGICAL FACTORS IN RELATION TO TRACK AND FIELD EVENTS OF SPRINT AND JUMPING TYPE

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Kemal Idrizović

2009-11-01

Full Text Available Assessment of the impact of motor manifestations and morphological features on the quality in the realization of track and field events of sprint and jumping type was the main issue of this research. The aim of the paper was to establish the impact of the ap- plied predictor systems of variables, motor and morphological ones, on the criteria va- riables, the results in track and field events: long jump and 60m sprint event. The results obtained in this research lead to the conclusion that this type of track and field events, or the quality of their realization in the motor sense mostly depends on the locomotive complexes of similar structure. However, in the morphological sense, such impact is va- riable.

Endurance, aerobic high-intensity, and repeated sprint cycling performance is unaffected by normobaric "Live High-Train Low"

DEFF Research Database (Denmark)

Bejder, Jacob; Andersen, Andreas Breenfeldt; Buchardt, Rie

2017-01-01

The aim was to investigate whether 6 weeks of normobaric "Live High-Train Low" (LHTL) using altitude tents affect highly trained athletes incremental peak power, 26-km time-trial cycling performance, 3-min all-out performance, and 30-s repeated sprint ability. In a double-blinded, placebo......-controlled cross-over design, seven highly trained triathletes were exposed to 6 weeks of normobaric hypoxia (LHTL) and normoxia (placebo) for 8 h/day. LHTL exposure consisted of 2 weeks at 2500 m, 2 weeks at 3000 m, and 2 weeks at 3500 m. Power output during an incremental test, ~26-km time trial, 3-min all...... conducted in a double-blinded, placebo-controlled cross-over design do not affect power output during an incremental test, a ~26-km time-trial test, or 3-min all-out exercise in highly trained triathletes. Furthermore, 30 s of repeated sprint ability was unaltered....

Effect of sodium bicarbonate and Beta-alanine on repeated sprints during intermittent exercise performed in hypoxia.

Science.gov (United States)

Saunders, Bryan; Sale, Craig; Harris, Roger C; Sunderland, Caroline

2014-04-01

To investigate the separate and combined effects of sodium bicarbonate and beta-alanine supplementation on repeated sprints during simulated match play performed in hypoxia. Study A: 20 recreationally active participants performed two trials following acute supplementation with either sodium bicarbonate (0.3 g·kg-1BM) or placebo (maltodextrin). Study B: 16 recreationally active participants were supplemented with either a placebo or beta-alanine for 5 weeks (6.4 g·day-1 for 4 weeks, 3.2 g·day-1 for 1 week), and performed one trial before supplementation (with maltodextrin) and two following supplementation (with sodium bicarbonate and maltodextrin). Trials consisted of 3 sets of 5 × 6 s repeated sprints performed during a football specific intermittent treadmill protocol performed in hypoxia (15.5% O2). Mean (MPO) and peak (PPO) power output were recorded as the performance measures. Study A: Overall MPO was lower with sodium bicarbonate than placebo (p = .02, 539.4 ± 84.5 vs. 554.0 ± 84.6 W), although there was no effect across sets (all p > .05). Study B: There was no effect of beta-alanine, or cosupplementation with sodium bicarbonate, on either parameter, although there was a trend toward higher MPO with sodium bicarbonate (p = .07). The effect of sodium bicarbonate on repeated sprints was equivocal, although there was no effect of beta-alanine or cosupplementation with sodium bicarbonate. Individual variation may have contributed to differences in results with sodium bicarbonate, although the lack of an effect with beta-alanine suggests this type of exercise may not be influenced by increased buffering capacity.

Giving students the run of sprinting models

Science.gov (United States)

Heck, André; Ellermeijer, Ton

2009-11-01

A biomechanical study of sprinting is an interesting task for students who have a background in mechanics and calculus. These students can work with real data and do practical investigations similar to the way sports scientists do research. Student research activities are viable when the students are familiar with tools to collect and work with data from sensors and video recordings and with modeling tools for comparing simulation and experimental results. This article describes a multipurpose system, named COACH, that offers a versatile integrated set of tools for learning, doing, and teaching mathematics and science in a computer-based inquiry approach. Automated tracking of reference points and correction of perspective distortion in videos, state-of-the-art algorithms for data smoothing and numerical differentiation, and graphical system dynamics based modeling are some of the built-in techniques that are suitable for motion analysis. Their implementation and their application in student activities involving models of running are discussed.

Effects of In-Season Explosive Strength Training on Maximal Leg Strength, Jumping, Sprinting, and Intermittent Aerobic Performance in Male Handball Athletes.

Science.gov (United States)

Hermassi, Souhail; Chelly, Mohamed Souhaiel; Fieseler, Georg; Bartels, Thomas; Schulze, Stephan; Delank, Karl-Stefan; Shephard, Roy J; Schwesig, René

2017-09-01

Background  Team handball is an intense ball sport with specific requirements on technical skills, tactical understanding, and physical performance. The ability of handball players to develop explosive efforts (e. g. sprinting, jumping, changing direction) is crucial to success. Objective  The purpose of this pilot study was to examine the effects of an in-season high-intensity strength training program on the physical performance of elite handball players. Materials and methods  Twenty-two handball players (a single national-level Tunisian team) were randomly assigned to a control group (CG; n = 10) or a training group (TG; n = 12). At the beginning of the pilot study, all subjects performed a battery of motor tests: one repetition maximum (1-RM) half-squat test, a repeated sprint test [6 × (2 × 15 m) shuttle sprints], squat jumps, counter movement jumps (CMJ), and the Yo-Yo intermittent recovery test level 1. The TG additionally performed a maximal leg strength program twice a week for 10 weeks immediately before engaging in regular handball training. Each strength training session included half-squat exercises to strengthen the lower limbs (80 - 95 % of 1-RM, 1 - 3 repetitions, 3 - 6 sets, 3 - 4 min rest between sets). The control group underwent no additional strength training. The motor test battery was repeated at the end of the study interventions. Results  In the TG, 3 parameters (maximal strength of lower limb: η² = 0.74; CMJ: η² = 0.70, and RSA best time: η² = 0.25) showed significant improvements, with large effect sizes (e. g. CMJ: d = 3.77). A reduction in performance for these same 3 parameters was observed in the CG (d = -0.24). Conclusions  The results support our hypothesis that additional strength training twice a week enhances the maximal strength of the lower limbs and jumping or repeated sprinting performance. There was no evidence of shuttle sprints ahead of regular

A Correlational Analysis of Tethered Swimming, Swim Sprint Performance and Dry-land Power Assessments.

Science.gov (United States)

Loturco, I; Barbosa, A C; Nocentini, R K; Pereira, L A; Kobal, R; Kitamura, K; Abad, C C C; Figueiredo, P; Nakamura, F Y

2016-03-01

Swimmers are often tested on both dry-land and in swimming exercises. The aim of this study was to test the relationships between dry-land, tethered force-time curve parameters and swimming performances in distances up to 200 m. 10 young male high-level swimmers were assessed using the maximal isometric bench-press and quarter-squat, mean propulsive power in jump-squat, squat and countermovement jumps (dry-land assessments), peak force, average force, rate of force development (RFD) and impulse (tethered swimming) and swimming times. Pearson product-moment correlations were calculated among the variables. Peak force and average force were very largely correlated with the 50- and 100-m swimming performances (r=- 0.82 and -0.74, respectively). Average force was very-largely/largely correlated with the 50- and 100-m performances (r=- 0.85 and -0.67, respectively). RFD and impulse were very-largely correlated with the 50-m time (r=- 0.72 and -0.76, respectively). Tethered swimming parameters were largely correlated (r=0.65 to 0.72) with mean propulsive power in jump-squat, squat-jump and countermovement jumps. Finally, mean propulsive power in jump-squat was largely correlated (r=- 0.70) with 50-m performance. Due to the significant correlations between dry-land assessments and tethered/actual swimming, coaches are encouraged to implement strategies able to increase leg power in sprint swimmers. © Georg Thieme Verlag KG Stuttgart · New York.

Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO2max during exercise.

Science.gov (United States)

Bagley, Liam; Slevin, Mark; Bradburn, Steven; Liu, Donghui; Murgatroyd, Chris; Morrissey, George; Carroll, Michael; Piasecki, Mathew; Gilmore, William S; McPhee, Jamie S

2016-01-01

The purpose of this study was to examine whether very short duration, very high intensity sprint interval training (SIT) leads to loss of body fat mass in association with improvements to VO 2 max and fatty acid oxidation, and to assess the extent of sex dimorphism in these physiological responses. A total of 24 men and 17 women (mean (SEM) age: 39 (±2) years; body mass index 24.6 (0.6)) completed measurements of the maximal rate of oxygen uptake (VO 2 max) and fatty acid oxidation (FATmax). Body fat and lean mass were measured by dual emission x-ray absorptiometry, and fasting blood lipid, glucose and insulin profiles were assessed before and after training. SIT consisted of 4×20 s sprints on a cycle ergometer at approximately 175% VO 2 max, three times per week for 12 weeks. Fat mass decreased by 1.0 kg, although men lost statistically significantly more fat than women both when expressed in Kg and as % body fat. VO 2 max increased by around 9%, but women improved VO 2 max significantly more than men. FATmax improved by around 13%, but fasting plasma glucose, insulin, total triglyceride, total cholesterol and high-density lipoprotein (HDL) did not change after training, while low-density lipoprotein decreased by 8% (p=0.028) and the HDL:Total Cholesterol ratio improved by 6%. There were no sex differences in these metabolic responses to training. These results show lower body fat %, and higher rates of fatty acid oxidation and VO 2 max after 12 weeks of training for just 4 min per week. Notably, women improved VO 2 max more than men, while men lost more fat than women.

Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO2max during exercise

Science.gov (United States)

Bagley, Liam; Slevin, Mark; Bradburn, Steven; Liu, Donghui; Murgatroyd, Chris; Morrissey, George; Carroll, Michael; Piasecki, Mathew; Gilmore, William S; McPhee, Jamie S

2016-01-01

Background The purpose of this study was to examine whether very short duration, very high intensity sprint interval training (SIT) leads to loss of body fat mass in association with improvements to VO2max and fatty acid oxidation, and to assess the extent of sex dimorphism in these physiological responses. Methods A total of 24 men and 17 women (mean (SEM) age: 39 (±2) years; body mass index 24.6 (0.6)) completed measurements of the maximal rate of oxygen uptake (VO2max) and fatty acid oxidation (FATmax). Body fat and lean mass were measured by dual emission x-ray absorptiometry, and fasting blood lipid, glucose and insulin profiles were assessed before and after training. SIT consisted of 4×20 s sprints on a cycle ergometer at approximately 175% VO2max, three times per week for 12 weeks. Results Fat mass decreased by 1.0 kg, although men lost statistically significantly more fat than women both when expressed in Kg and as % body fat. VO2max increased by around 9%, but women improved VO2max significantly more than men. FATmax improved by around 13%, but fasting plasma glucose, insulin, total triglyceride, total cholesterol and high-density lipoprotein (HDL) did not change after training, while low-density lipoprotein decreased by 8% (p=0.028) and the HDL:Total Cholesterol ratio improved by 6%. There were no sex differences in these metabolic responses to training. Conclusions These results show lower body fat %, and higher rates of fatty acid oxidation and VO2max after 12 weeks of training for just 4 min per week. Notably, women improved VO2max more than men, while men lost more fat than women. PMID:27900150

Thermal dependence of sprint performance in the lizard Psammodromus algirus along a 2200-meter elevational gradient: Cold-habitat lizards do not perform better at low temperatures.

Science.gov (United States)

Zamora-Camacho, Francisco Javier; Rubiño-Hispán, María Virtudes; Reguera, Senda; Moreno-Rueda, Gregorio

2015-08-01

Sprint speed has a capital relevance in most animals' fitness, mainly for fleeing from predators. Sprint performance is maximal within a certain range of body temperatures in ectotherms, whose thermal upkeep relies on exogenous thermal sources. Ectotherms can respond to diverse thermal environments either by shifting their thermal preferences or maintaining them through different adaptive mechanisms. Here, we tested whether maximum sprint speed of a lizard that shows conservative thermal ecology along a 2200-meter elevational gradient differs with body temperature in lizards from different elevations. Lizards ran faster at optimum than at suboptimum body temperature. Notably, high-elevation lizards were not faster than mid- and low-elevation lizards at suboptimum body temperature, despite their low-quality thermal environment. This result suggests that both preferred body temperature and thermal dependence of speed performance are co-adapted along the elevational gradient. High-elevation lizards display a number of thermoregulatory strategies that allow them to achieve high optimum body temperatures in a low thermal-quality habitat and thus maximize speed performance. As for reproductive condition, we did not find any effect of it on sprint speed, or any significant interaction with elevation or body temperature. However, strikingly, gravid females were significantly slower than males and non-gravid females at suboptimum temperature, but performed similarly well at optimal temperature. Copyright © 2015 Elsevier Ltd. All rights reserved.

Environmental differences in substrate mechanics do not affect sprinting performance in sand lizards (Uma scoparia and Callisaurus draconoides).

Science.gov (United States)

Korff, Wyatt L; McHenry, Matthew J

2011-01-01

Running performance depends on a mechanical interaction between the feet of an animal and the substrate. This interaction may differ between two species of sand lizard from the Mojave Desert that have different locomotor morphologies and habitat distributions. Uma scorparia possesses toe fringes and inhabits dunes, whereas the closely related Callisaurus draconoides lacks fringes and is found on dune and wash habitats. The present study evaluated whether these distribution patterns are related to differential locomotor performance on the fine sand of the dunes and the course sand of the wash habitat. We measured the kinematics of sprinting and characterized differences in grain size distribution and surface strength of the soil in both habitats. Although wash sand had a surface strength (15.4±6.2 kPa) that was more than three times that of dune sand (4.7±2.1 kPa), both species ran with similar sprinting performance on the two types of soil. The broadly distributed C. draconoides ran with a slightly (22%) faster maximum speed (2.2±0.2 m s(-1)) than the dune-dwelling U. scorparia (1.8±0.2 m s(-1)) on dune sand, but not on wash sand. Furthermore, there were no significant differences in maximum acceleration or the time to attain maximum speed between species or between substrates. These results suggest that differences in habitat distribution between these species are not related to locomotor performance and that sprinting ability is dominated neither by environmental differences in substrate nor the presence of toe fringes.

Sprint interval and moderate-intensity cycling training differentially affect adiposity and aerobic capacity in overweight young-adult women.

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Higgins, Simon; Fedewa, Michael V; Hathaway, Elizabeth D; Schmidt, Michael D; Evans, Ellen M

2016-11-01

The purpose of the study was to examine the effects of sprint interval training (SIT) and moderate-intensity continuous cycle training (MICT), with equal estimated energy expenditure during training on body composition and aerobic capacity. Body composition measured via dual-energy X-ray absorptiometry and aerobic capacity were assessed following 6 weeks of training in previously inactive overweight/obese young women (n = 52; age, 20.4 ± 1.5 years; body mass index, 30.3 ± 4.5 kg·m -2 , 67.3% white). Training was performed in a group-exercise format that mimicked cycling classes offered by commercial fitness facilities, and included 3 weekly sessions of either 30-s "all-out" sprints followed by 4 min of active recovery (SIT), or continuous cycling at 60%-70% heart rate reserve to expend a similar amount of energy. Participants were randomized to SIT or MICT, attended a similar number of sessions (15.0 ± 1.5 sessions vs. 15.8 ± 1.9 sessions, P = 0.097) and expended a similar amount of energy (541.8 ± 104.6 kJ·session -1 vs. 553.5 ± 138.1 kJ·session -1 , P = 0.250). Without significant changes in body mass (P > 0.05), greater relative reductions occurred in SIT than in MICT in total fat mass (3.6% ± 5.6% vs. 0.6% ± 3.9%, P = 0.007), and android fat mass (6.6% ± 6.9% vs. 0.7% ± 6.5%, P = 0.002). Aerobic capacity (mL·kg -1 ·min -1 ) increased significantly following both interventions (P interval cycling reduces adiposity and increases aerobic capacity more than continuous moderate-intensity cycling of equal estimated energy expenditure in overweight/obese young women.

Officiating Role Influences the Physical Match Activity Profiles of Rugby League Touch Judges and Referees

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Pearce Leesa

2017-08-01

Full Text Available This study investigated the effect of the officiating role on physical activity profiles of rugby league match officials during match-play. Physical performance indicators were collated from 23 match officials, resulting in 78 observations. Match officials were categorised into two groups: referees and touch judges. Microtechnology facilitated the quantification of total distance (m, relative distance (m⋅min-1, maximum velocity (m⋅s-1, the percentage of high intensity running distance (% total > 3.01 m⋅s-1, walking distance (5 m⋅s-1. Multivariate analysis modelled the main effect of the officiating role with follow up univariate analyses identifying significant differences. A significant effect was noted (V = 750; F(8, 66 = 24.71; p < 0.05 with referees covering a greater total distance (7767 ± 585 vs. 7022 ± 759 m, relative distance (90 ± 6 vs. 82 ± 8 m⋅min-1, jogging distance (3772 ± 752 vs. 3110 ± 553 m, and fast jogging distance (2565 ± 631 vs. 1816 ± 440 m compared to touch judges. Touch judges covered greater distances while sprinting (1012 ± 385 vs. 654 ± 241 m. Results provide important guidance in the development of training programs for match officials.

Proximal Neuromuscular Control Protects Against Hamstring Injuries in Male Soccer Players: A Prospective Study With Electromyography Time-Series Analysis During Maximal Sprinting.

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Schuermans, Joke; Danneels, Lieven; Van Tiggelen, Damien; Palmans, Tanneke; Witvrouw, Erik

2017-05-01

With their unremittingly high incidence rate and detrimental functional repercussions, hamstring injuries remain a substantial problem in male soccer. Proximal neuromuscular control ("core stability") is considered to be of key importance in primary and secondary hamstring injury prevention, although scientific evidence and insights on the exact nature of the core-hamstring association are nonexistent at present. The muscle activation pattern throughout the running cycle would not differ between participants based on injury occurrence during follow-up. Case-control study; Level of evidence, 3. Sixty amateur soccer players participated in a multimuscle surface electromyography (sEMG) assessment during maximal acceleration to full-speed sprinting. Subsequently, hamstring injury occurrence was registered during a 1.5-season follow-up period. Hamstring, gluteal, and trunk muscle activity time series during the airborne and stance phases of acceleration were evaluated and statistically explored for a possible causal association with injury occurrence and absence from sport during follow-up. Players who did not experience a hamstring injury during follow-up had significantly higher amounts of gluteal muscle activity during the front swing phase ( P = .027) and higher amounts of trunk muscle activity during the backswing phase of sprinting ( P = .042). In particular, the risk of sustaining a hamstring injury during follow-up lowered by 20% and 6%, with a 10% increment in normalized muscle activity of the gluteus maximus during the front swing and the trunk muscles during the backswing, respectively ( P hamstring injury occurrence in male soccer players. Higher amounts of gluteal and trunk muscle activity during the airborne phases of sprinting were associated with a lower risk of hamstring injuries during follow-up. Hence, the present results provide a basis for improved, evidence-based rehabilitation and prevention, particularly focusing on increasing neuromuscular

Sex-specific trade-offs and compensatory mechanisms: bite force and sprint speed pose conflicting demands on the design of geckos (Hemidactylus frenatus).

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Cameron, S F; Wynn, M L; Wilson, R S

2013-10-15

One of the more intuitive viability costs that can result from the possession of exaggerated sexually selected traits is increased predation pressure as a result of reduced locomotor capacity. Despite mixed empirical support for such locomotor costs, recent studies suggest that such costs may be masked by compensatory traits that effectively offset any detrimental effects. In this study, we provide a comprehensive assessment of the locomotor costs associated with improved male-male competitive ability by simultaneously testing for locomotor trade-offs and potential compensatory mechanisms in territorial male and non-territorial female geckos. Fighting capacity and escape performance of male Asian house geckos (Hemidactylus frenatus) are likely to pose conflicting demands on the optimum phenotype for each task. Highly territorial and aggressive males may require greater investment in head size/strength but such an enhancement may affect overall escape performance. Among male geckos, we found that greater biting capacity because of larger head size was associated with reduced sprint performance; this trade-off was further exacerbated when sprinting on an incline. Females, however, showed no evidence of this trade-off on either flat or inclined surfaces. The sex specificity of this trade-off suggests that the sexes differ in their optimal strategies for dealing with the conflicting requirements of bite force and sprint speed. Unlike males, female H. frenatus had a positive association between hind-limb length and head size, suggesting that they have utilised a compensatory mechanism to alleviate the possible locomotor costs of larger head sizes. It appears that there is greater selection on traits that improve fighting ability (bite force) for males, but it is viability traits (sprint speed) that appear to be of greater importance for females. Our results emphasise that only by examining both functional trade-offs and potential compensatory mechanisms is it possible

Research of the stopping distance for different road conditions

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Daniel LYUBENOV

2011-01-01

Full Text Available In this paper a modern method for determination of stopping distance is represented. Application of the non-contact VBOX 3i 100Hz GPS Data Logger speed and distance measurement system is represented. A description of the total stopping distance of vehicle main components - driver reaction time, vehicle reaction time and vehicle braking capability has been made. Research of the total stopping distance of a vehicle for different road conditions has been made. The results for the stopping distance can be very useful in the expert practice.

Total number of planetary nebulae in different galaxies and the PN distance scale.

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Peimbert, M.

1990-12-01

RESUMEN A partir de una muestra de quince galaxias se encuentra que la tasa de natalidad de nebulosas planetarias por unidad de luminosidad, , disminuye al aumentar la luminosidad y al aumentar (B - V)0. Se discuten posibles explicaciones para estos resultados. Se estima el valor de para la Galaxia y a partir de el se encuentra que el numero total de nebulosas planetarias en nuestra galaxia con R de 7200 j 1800. El valor galactico de implica que la mayorfa de las estrellas de masa intermedia pasa por la etapa de nebulosa planetaria. El valor galactico de , la tasa de mortalidad estelar por unidad de luminosidad y la tasa de natalidad de enanas blancas favorecen escalas de distancias largas para nebulosas planetarias, como la de Cudworth (1974) y la de Mallik y Peimbert (1988). ABSTRACT From a sample of fifteen galaxies it is found that the birth rate of PN per unit luminosity, , decreases with increasing luminosity and with increasing (B - V)0 possible reasons for these relationships are discussed. The value for the Galaxy is estimated and, from it, a total number of PN of 7200 # 1800 wid R < 0.64 pc is obtained. The galactic value implies that most of the intermediate mass stars go through the PN stage. The galactic value, the stellar death rate per unit luminosity and the white dwarf birth rate are in favor of long distance scales to PN like those of Cudworth (1974) and Mallik and (1988). Key wonis: NEBULAE.PLANETARY - STARS-EVOLUTION - STARS-SThLIAR STA. S

Protein characterization of pasteurized milk, cheese whey and their mixtures by using the CEM SprintTM analyzer

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Igor Moura Paiva

2016-06-01

Full Text Available In this work, the protein analyzer SprintTM was assessed regarding its capacity of predicting addition of whey in milk. This type of practice is relatively common in dairy plants, since whey, as it is a protein component, may be added with little loss of milk protein content. Besides,its incorrect elimination contributes to environmental pollution. Mixtures of milk and whey were prepared in different levels of addition and two methods of milk partition were tested. The results indicated that the concentration of trichloroacetic acid (TCA from the selected method was not suitable for the present purpose while the chosen method using glacial acetic acid (GAA has presented a satisfactory separation of the soluble and insoluble milk components. Even though the concentration of whey protein and casein are the essential parameters for determining whey addition in milk, the use of measurements from total protein was important in order to improve the linearity of the method due to the fact that the rates whey protein/total protein and casein/total protein presented the best results concerning fraud prediction capacity. Therefore, as the equipment is a rapid, safe and efficient platform, it can be used as an alternative to be implemented in laboratories of food quality control which perform or plan to perform assays to verify the whey addition in fluid milk.

The Effect of a Simulated Basketball Game on Players’ Sprint and Jump Performance, Temperature and Muscle Damage

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Pliauga Vytautas

2015-06-01

Full Text Available Despite extensive data regarding the demands of playing basketball, the relative importance of factors that cause fatigue and muscle potentiation has been explored only tentatively and remains unclear. The aim of this experimental field study was to assess changes in leg muscle power and relate these changes to body temperature modifications and indices of exercise-induced muscle damage in response to a simulated basketball game. College-level male basketball players (n=10 were divided into two teams to play a simulated basketball game. Ten-meter sprint and vertical counter-movement jump tests, core body temperature and creatine-kinase activity were measured within 48 h after the game. The participants’ body temperatures increased after a warm-up (1.9%, p200%, p30%, p<0.05 after the game, indicating damage to the players’ muscles. The basketball players’ sprint and jump performance appear to be at least in part associated with body temperature changes, which might contribute to counteract fatigue during the larger part of a basketball game.

The Effect of a Simulated Basketball Game on Players' Sprint and Jump Performance, Temperature and Muscle Damage.

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Pliauga, Vytautas; Kamandulis, Sigitas; Dargevičiūtė, Gintarė; Jaszczanin, Jan; Klizienė, Irina; Stanislovaitienė, Jūratė; Stanislovaitis, Aleksas

2015-06-27

Despite extensive data regarding the demands of playing basketball, the relative importance of factors that cause fatigue and muscle potentiation has been explored only tentatively and remains unclear. The aim of this experimental field study was to assess changes in leg muscle power and relate these changes to body temperature modifications and indices of exercise-induced muscle damage in response to a simulated basketball game. College-level male basketball players (n=10) were divided into two teams to play a simulated basketball game. Ten-meter sprint and vertical counter-movement jump tests, core body temperature and creatine-kinase activity were measured within 48 h after the game. The participants' body temperatures increased after a warm-up (1.9%, pjump height (3.8%, pbasketball game. There was a significant increase in creatine-kinase at 24 h (>200%, p30%, pbasketball players' sprint and jump performance appear to be at least in part associated with body temperature changes, which might contribute to counteract fatigue during the larger part of a basketball game.

The Effect of a Simulated Basketball Game on Players’ Sprint and Jump Performance, Temperature and Muscle Damage

Science.gov (United States)

Pliauga, Vytautas; Kamandulis, Sigitas; Dargevičiūtė, Gintarė; Jaszczanin, Jan; Klizienė, Irina; Stanislovaitienė, Jūratė; Stanislovaitis, Aleksas

2015-01-01

Despite extensive data regarding the demands of playing basketball, the relative importance of factors that cause fatigue and muscle potentiation has been explored only tentatively and remains unclear. The aim of this experimental field study was to assess changes in leg muscle power and relate these changes to body temperature modifications and indices of exercise-induced muscle damage in response to a simulated basketball game. College-level male basketball players (n=10) were divided into two teams to play a simulated basketball game. Ten-meter sprint and vertical counter-movement jump tests, core body temperature and creatine-kinase activity were measured within 48 h after the game. The participants’ body temperatures increased after a warm-up (1.9%, pjump height (3.8%, pbasketball game. There was a significant increase in creatine-kinase at 24 h (>200%, p30%, pbasketball players’ sprint and jump performance appear to be at least in part associated with body temperature changes, which might contribute to counteract fatigue during the larger part of a basketball game. PMID:26240660

A cost-effectiveness analysis of a proactive management strategy for the Sprint Fidelis recall: a probabilistic decision analysis model.

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Bashir, Jamil; Cowan, Simone; Raymakers, Adam; Yamashita, Michael; Danter, Matthew; Krahn, Andrew; Lynd, Larry D

2013-12-01

The management of the recall is complicated by the competing risks of lead failure and complications that can occur with lead revision. Many of these patients are currently undergoing an elective generator change--an ideal time to consider lead revision. To determine the cost-effectiveness of a proactive management strategy for the Sprint Fidelis recall. We obtained detailed clinical outcomes and costing data from a retrospective analysis of 341 patients who received the Sprint Fidelis lead in British Columbia, where patients younger than 60 years were offered lead extraction when undergoing generator replacement. These population-based data were used to construct and populate a probabilistic Markov model in which a proactive management strategy was compared to a conservative strategy to determine the incremental cost per lead failure avoided. In our population, elective lead revisions were half the cost of emergent revisions and had a lower complication rate. In the model, the incremental cost-effectiveness ratio of proactive lead revision versus a recommended monitoring strategy was $12,779 per lead failure avoided. The proactive strategy resulted in 21 fewer failures per 100 patients treated and reduced the chance of an additional complication from an unexpected surgery. Cost-effectiveness analysis suggests that prospective lead revision should be considered when patients with a Sprint Fidelis lead present for pulse generator change. Elective revision of the lead is justified even when 25% of the population is operated on per year, and in some scenarios, it is both less costly and provides a better outcome. © 2013 Heart Rhythm Society Published by Heart Rhythm Society All rights reserved.

Influence of training intensity on adaptations in acid/base transport proteins, muscle buffer capacity, and repeated-sprint ability in active men.

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McGinley, Cian; Bishop, David J

2016-12-01

McGinley C, Bishop DJ. Influence of training intensity on adaptations in acid/base transport proteins, muscle buffer capacity, and repeated-sprint ability in active men. J Appl Physiol 121: 1290-1305, 2016. First published October 14, 2016; doi:10.1152/japplphysiol.00630.2016-This study measured the adaptive response to exercise training for each of the acid-base transport protein families, including providing isoform-specific evidence for the monocarboxylate transporter (MCT)1/4 chaperone protein basigin and for the electrogenic sodium-bicarbonate cotransporter (NBCe)1. We investigated whether 4 wk of work-matched, high-intensity interval training (HIIT), performed either just above the lactate threshold (HIITΔ20; n = 8), or close to peak aerobic power (HIITΔ90; n = 8), influenced adaptations in acid-base transport protein abundance, nonbicarbonate muscle buffer capacity (βm in vitro ), and exercise capacity in active men. Training intensity did not discriminate between adaptations for most proteins measured, with abundance of MCT1, sodium/hydrogen exchanger (NHE) 1, NBCe1, carbonic anhydrase (CA) II, and CAXIV increasing after 4 wk, whereas there was little change in CAIII and CAIV abundance. βm in vitro also did not change. However, MCT4 protein content only increased for HIITΔ20 [effect size (ES): 1.06, 90% confidence limits × / ÷ 0.77], whereas basigin protein content only increased for HIITΔ90 (ES: 1.49, × / ÷ 1.42). Repeated-sprint ability (5 × 6-s sprints; 24 s passive rest) improved similarly for both groups. Power at the lactate threshold only improved for HIITΔ20 (ES: 0.49; 90% confidence limits ± 0.38), whereas peak O 2 uptake did not change for either group. Detraining was characterized by the loss of adaptations for all of the proteins measured and for repeated-sprint ability 6 wk after removing the stimulus of HIIT. In conclusion, 4 wk of HIIT induced improvements in each of the acid-base transport protein families, but, remarkably, a 40

Effects of inspiratory muscle training on respiratory function and repetitive sprint performance in wheelchair basketball players.

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Goosey-Tolfrey, V; Foden, E; Perret, C; Degens, H

2010-07-01

There is considerable evidence that respiratory muscle training improves pulmonary function, quality of life and exercise performance in healthy athletic populations. The benefits for wheelchair athletes are less well understood. Therefore, in the present study, influence of inspiratory muscle training (IMT) on respiratory function and repetitive propulsive sprint performance in wheelchair basketball players was examined. Using a placebo-controlled design, 16 wheelchair athletes were divided to an experimental (IMT; n=8) or placebo (sham-IMT; n=8) group based on selective grouping criteria. 30 dynamic breaths were performed by the IMT group twice daily at a resistance equivalent to 50% maximum inspiratory pressure (MIP), and 60 slow breaths were performed by the sham-IMT group once a day at 15% MIP for a period of 6 weeks. In the IMT group, both MIP and maximum expiratory pressure (17% and 23%, respectively; ptraining device suggested "less breathlessness" and "less tightness in the chest during the training". Although there was no improvement in sprint performance, an improved respiratory muscle function and quality of life were reported by participants in both the IMT and sham-IMT groups.

Jump Squat is More Related to Sprinting and Jumping Abilities than Olympic Push Press.

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Loturco, I; Kobal, R; Maldonado, T; Piazzi, A F; Bottino, A; Kitamura, K; Abad, C C C; Pereira, L A; Nakamura, F Y

2017-07-01

The aim of this study was to test the relationships between jump squat (JS) and Olympic push press (OPP) power outputs and performance in sprint, squat jump (SJ), countermovement jump (CMJ) and change of direction (COD) speed tests in elite soccer players. 27 athletes performed a maximum power load test to determine their bar mean propulsive power (MPP) and bar mean propulsive velocity (MPV) in the JS and OPP exercises. Magnitude-based inference was used to compare the exercises. The MPV was almost certainly higher in the OPP than in the JS. The MPP relative to body mass (MPP REL) was possibly higher in the OPP. Only the JS MPP REL presented very large correlations with linear speed ( r> 0.7, for speed in 5, 10, 20 and 30 m) and vertical jumping abilities ( r> 0.8, for SJ and CMJ), and moderate correlation with COD speed ( r= 0.45). Although significant (except for COD), the associations between OPP outcomes and field-based measurements (speed, SJ and CMJ) were all moderate, ranging from 0.40 to 0.48. In a group composed of elite soccer players, the JS exercise is more associated with jumping and sprinting abilities than the OPP. Longitudinal studies are needed to confirm if these strong relationships imply superior training effects in favor of the JS exercise. © Georg Thieme Verlag KG Stuttgart · New York.

Determinant Factors of the Squat Jump in Sprinting and Jumping Athletes

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González-Badillo Juan José

2017-08-01

Full Text Available The aim of this study was to assess the relationship between strength variables and maximum velocity (Vmax in the squat jump (SJ in sprinting and jumping athletes. Thirty-two sprinting and jumping athletes of national level (25.4 ± 4.5 years; 79.4 ± 6.9 kg and 180.4 ± 6.0 cm participated in the study. Vmax in the SJ showed significant relationships with peak force 1 (PF1 (r = 0.82, p ≤ 0.001, peak force 2 (PF2 (r = 0.68, p ≤ 0.001, PF2 by controlling for PF1 (r = 0.30, non-significant, the maximum rate of force development at peak force 1 (RFDmax1 (r = 0.62, p ≤ 0.001, mean RFD 1 (RFDmean1 (r = 0.48, p ≤ 0.01, mean RFD 2 (RFDmean2 (r = 0.70, p ≤ 0.001, force at RFDmax1 (r = 0.36, p ≤ 0.05, force at RFDmax2 (r = 0.83, p ≤ 0.001 and force at RFDmax2 by controlling for PF1 (r = 0.40, p ≤ 0.05. However, Vmax in the SJ was associated negatively with the ratio PF2/PF1 (r = -0.54, p ≤ 0.01, time at peak force 2 (Tp2 (r = -0.64, p ≤ 0.001 and maximum rate of force development at peak force 2 (RFDmax2 (r = -0.71, p ≤ 0.001. These findings indicate that the peak force achieved at the beginning of the movement (PF1 is the main predictor of performance in jumping, although the RFDmax values and the ratio PF2/PF1 are also variables to be taken into account when analyzing the determinant factors of vertical jumping.

SHORT DURATIONS OF STATIC STRETCHING WHEN COMBINED WITH DYNAMIC STRETCHING DO NOT IMPAIR REPEATED SPRINTS AND AGILITY

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Del P. Wong

2011-06-01

Full Text Available This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA and change of direction (COD. Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s. Three dynamic stretching exercises of 30 s duration were then performed (90 s total. Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p < 0.001. However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (< 90 s static stretching may not have provided sufficient stimulus to elicit performance impairments

Effects of small-sided games and high-intensity interval training on aerobic and repeated sprint performance and peripheral muscle oxygenation changes in elite junior basketball players.

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Delextrat, A; Gruet, M; Bieuzen, F

2018-03-06

The aim of the current study was to compare the effects of 6 weeks of small-sided game (SSG) and high-intensity interval training (HIIT) on aerobic fitness and muscle oxygenation during a repeated sprint (RS) sequence in elite male junior basketball players. Twenty participants (14.3 ± 0.5 years; 176.8 ± 12.5 cm; 74.5 ± 9.8 kg) performed pre- and post-tests interspersed by 6-weeks of SSG or HIIT training. Testing sessions consisted of the 30-15 Intermittent Fitness Test and a RS sequence (two bouts of 15-s). During RS, muscle oxygenation parameters (tissue saturation index (TSI, %), post-sprint muscle reoxygenation rate) were measured by near-infrared spectroscopy (NIRS). The results showed that both training interventions similarly improved maximal aerobic speed (VIFT, 3.4 and 4.1%, respectively for HIIT and SSG, Ptraining interventions also resulted in a greater ΔTSI during the second sprint (47.8% to 114%, Ptrainings are applicable methodologies to improve in-season aerobic and anaerobic fitness capacities in junior basketball players.

Muscle morphology of the vastus lateralis is strongly related to ergometer performance, sprint capacity and endurance capacity in Olympic rowers

NARCIS (Netherlands)

van der Zwaard, Stephan; Weide, Guido; Levels, Koen; Eikelboom, Michelle R.I.; Noordhof, Dionne A.; Hofmijster, Mathijs J.; van der Laarse, Willem J.; de Koning, Jos J.; de Ruiter, Cornelis J.; Jaspers, Richard T.

2018-01-01

Rowers need to combine high sprint and endurance capacities. Muscle morphology largely explains muscle power generating capacity, however, little is known on how muscle morphology relates to rowing performance measures. The aim was to determine how muscle morphology of the vastus lateralis relates

Final Project Closeout Report for Sprint Hydrogen Fuel Cell (HFC) Deployment Project in California, Gulf Coast and Eastern Seaboard Markets

Energy Technology Data Exchange (ETDEWEB)

Kenny, Kevin [Sprint, Reston, VA (United States); Bradley, Dwayne [Burns & McDonnell, Kansas City, MO (United States)

2015-09-01

Sprint is one of the telecommunications industry leaders in the deployment of hydrogen fuel cell (HFC) systems to provide backup power for their mission critical wireless network facilities. With several hundred fuel cells commissioned in California, states in the gulf coast region, and along the upper eastern seaboard. A strong incentive for advancing the integration of fuel cells into the Sprint network came through the award of a Department of Energy (DOE) grant focused on Market Transformation activities for project (EE0000486). This grant was funded by the 2009 American Recovery and Reinvestment Act (ARRA). The funding provided by DOE ($7.295M) was allocated to support the installation of 260 new HFC systems, equipped with an on-site refillable Medium Pressure Hydrogen Storage Solution (MPHSS), as well as for the conversion of 21 low pressure hydrogen systems to the MPHSS, in hopes of reducing barriers to market acceptance.

SPRINT-INTERVAL TRAINING INDUCES HEAT SHOCK PROTEIN 72 IN RAT SKELETAL MUSCLES

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Yuji Ogura

2006-06-01

Full Text Available Previous studies have demonstrated that endurance exercise training increases the level of heat shock proteins (HSPs in skeletal muscles. However, little attention has been drawn to the effects of high intensity-short duration exercise, or sprint- interval training (SIT on HSP72 level in rat skeletal muscles. This study performed to test the hypothesis that the SIT would induce the HSP72 in fast and slow skeletal muscles of rats. Young male Wistar rats (8 weeks old were randomly assigned to a control (CON or a SIT group (n = 8/group. Animals in the SIT group were trained (1 min/sprint, 6~10 sets/day and 5~6 days/week on a treadmill for 9 weeks. After the training period, HSP72 levels in the plantaris (fast and soleus (slow muscles were analyzed by Western blotting method. Enzyme activities (hexokinase, phosphofructokinase and citrate synthase and histochemical properties (muscle fiber type compositions and cross sectional area in both muscles were also determined. The SIT resulted in significantly (p < 0.05 higher levels of HSP72 in both the plantaris and soleus muscles compared to the CON group, with the plantaris producing a greater HSP72 increase than the soleus (plantaris; 550 ± 116%, soleus; 26 ± 8%, p < 0.05. Further, there were bioenergetic improvements, fast-to-slow shift of muscle fiber composition and hypertrophy in the type IIA fiber only in the plantaris muscle. These findings indicate that the SIT program increases HSP72 level of the rat hindlimb muscles, and the SIT-induced accumulation of HSP72 differs between fast and slow muscles

Feasibility and reliability of measuring strength, sprint power, and aerobic capacity in athletes and non-athletes with cerebral palsy

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De Groot, Sonja; Janssen, Thomas W. J.; Evers, Marijn; Van der Luijt, Pieter; Nienhuys, Kirsten N. G.; Dallmeijer, Annet J.

Aim The aim of this study was to analyse the feasibility and reliability of the tests used to determine muscle strength, sprint power, and aerobic capacity in athletes and non-athletes with cerebral palsy (CP). Methods Twenty individuals with spastic CP (four females, 16 males; age range 1849y;

Selective Changes in the Mechanical Capacities of Lower-Body Muscles After Cycle-Ergometer Sprint Training Against Heavy and Light Resistances.

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García-Ramos, Amador; Torrejón, Alejandro; Pérez-Castilla, Alejandro; Morales-Artacho, Antonio J; Jaric, Slobodan

2018-03-01

To explore the feasibility of the linear force-velocity (F-V) modeling approach to detect selective changes of F-V parameters (ie, maximum force [F 0 ], maximum velocity [V 0 ], F-V slope [a], and maximum power [P 0 ]) after a sprint-training program. Twenty-seven men were randomly assigned to a heavy-load group (HLG), light-load group (LLG), or control group (CG). The training sessions (6 wk × 2 sessions/wk) comprised performing 8 maximal-effort sprints against either heavy (HLG) or light (LLG) resistances in leg cycle-ergometer exercise. Pre- and posttest consisted of the same task performed against 4 different resistances that enabled the determination of the F-V parameters through the application of the multiple-point method (4 resistances used for the F-V modeling) and the recently proposed 2-point method (only the 2 most distinctive resistances used). Both the multiple-point and the 2-point methods revealed high reliability (all coefficients of variation .80) while also being able to detect the group-specific training-related changes. Large increments of F 0 , a, and P 0 were observed in HLG compared with LLG and CG (effect size [ES] = 1.29-2.02). Moderate increments of V 0 were observed in LLG compared with HLG and CG (ES = 0.87-1.15). Short-term sprint training on a leg cycle ergometer induces specific changes in F-V parameters that can be accurately monitored by applying just 2 distinctive resistances during routine testing.

A Comparison Study on Motion/Force Transmissibility of Two Typical 3-DOF Parallel Manipulators: The Sprint Z3 and A3 Tool Heads

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Xiang Chen

2014-01-01

Full Text Available This paper presents a comparison study of two important three-degree-of-freedom (DOF parallel manipulators, the Sprint Z3 head and the A3 head, both commonly used in industry. As an initial step, the inverse kinematics are derived and an analysis of two classes of limbs is carried out via screw theory. For comparison, three transmission indices are then defined to describe their motion/force transmission performance. Based on the same main parameters, the compared results reveal some distinct characteristics in addition to the similarities between the two parallel manipulators. To a certain extent, the A3 head outperforms the common Sprint Z3 head, providing a new and satisfactory option for a machine tool head in industry.

Representing distance, consuming distance

DEFF Research Database (Denmark)

Larsen, Gunvor Riber

Title: Representing Distance, Consuming Distance Abstract: Distance is a condition for corporeal and virtual mobilities, for desired and actual travel, but yet it has received relatively little attention as a theoretical entity in its own right. Understandings of and assumptions about distance...... are being consumed in the contemporary society, in the same way as places, media, cultures and status are being consumed (Urry 1995, Featherstone 2007). An exploration of distance and its representations through contemporary consumption theory could expose what role distance plays in forming...

Feasibility and reliability of measuring strength, sprint power, and aerobic capacity in athletes and non-athletes with cerebral palsy

NARCIS (Netherlands)

de Groot, S.; Janssen, T.W.J.; Evers, M.; Van der Luijt, P.; Nienhuys, K.N.G.; Dallmeijer, A.J.

2012-01-01

Aim The aim of this study was to analyse the feasibility and reliability of the tests used to determine muscle strength, sprint power, and aerobic capacity in athletes and non-athletes with cerebral palsy (CP). Methods Twenty individuals with spastic CP (four females, 16 males; age range 18-49y;

Metabolic rate and gross efficiency at high work rates in world class and national level sprint skiers.

Science.gov (United States)

Sandbakk, Øyvind; Holmberg, Hans-Christer; Leirdal, Stig; Ettema, Gertjan

2010-06-01

The present study investigated metabolic rate (MR) and gross efficiency (GE) at moderate and high work rates, and the relationships to gross kinematics and physical characteristics in elite cross-country skiers. Eight world class (WC) and eight national level (NL) male sprint cross-country skiers performed three 5-min stages using the skating G3 technique, whilst roller skiing on a treadmill. GE was calculated by dividing work rate by MR. Work rate was calculated as the sum of power against gravity and frictional rolling forces. MR was calculated using gas exchange and blood lactate values. Gross kinematics, i.e. cycle length (CL) and cycle rate (CR) were measured by video analysis. Furthermore, the skiers were tested for time to exhaustion (TTE), peak oxygen uptake (VO(2peak)), and maximal speed (V(max)) on the treadmill, and maximal strength in the laboratory. Individual performance level in sprint skating was determined by FIS points. WC skiers did not differ in aerobic MR, but showed lower anaerobic MR and higher GE than NL skiers at a given speed (all P higher V(max) and TTE (all P better technique and to technique-specific power.

Recovery of voluntary and evoked muscle performance following intermittent-sprint exercise in the heat.

Science.gov (United States)

Duffield, Rob; King, Monique; Skein, Melissa

2009-06-01

This study investigated the effects of hot conditions on the acute recovery of voluntary and evoked muscle performance and physiological responses following intermittent exercise. Seven youth male and six female team-sport athletes performed two sessions separated by 7 d, involving a 30-min exercise protocol and 60-min passive recovery in either 22 degrees C or 33 degrees C and 40% relative humidity. The exercise protocol involved a 20-s maximal sprint every 5 min, separated by constant-intensity exercise at 100 W on a cycle ergometer. Maximal voluntary contraction (MVC) and a resting evoked twitch (Pf) of the right knee extensors were assessed before and immediately following exercise and again 15, 30, and 60 min postexercise, and capillary blood was obtained at the same time points to measure lactate, pH, and HCO3. During and following exercise, core temperature, heart rate and rating of perceived exertion (RPE) were also measured. No differences (P=0.73 to 0.95) in peak power during repeated sprints were present between conditions. Postexercise MVC was reduced (Pheat (83+/-10 vs 74+/-11% recovered). Both heart rate and core temperature were significantly higher (Precovery in the heat. Capillary blood values did not differ between conditions at any time point, whereas sessional RPE was higher 60 min postexercise in the heat. The current data suggests that passive recovery in warm temperatures not only delays cardiovascular and thermal recovery, but may also slow the recovery of MVC and RPE.

Análisis de los factores de rendimiento en triatlón distancia sprint

OpenAIRE

Cejuela Anta, Roberto; Pérez Turpin, José Antonio; Villa Vicente, José Gerardo; Cortell-Tormo, Juan M.; Rodríguez Marroyo, José Antonio

2007-01-01

El triatlón es un deporte combinado y de resistencia donde se desarrollan sin solución de continuidad natación, ciclismo y carrera a pie, siempre en ese orden y sin parar el cronometro. La distancia Sprint es la más corta según el reglamento y sobre la cual se disputan mayor número de pruebas (0’750 km, 20 km, 5 km). Determinar los factores de rendimiento es fundamental para optimizar el entrenamiento de una modalidad deportiva. La diversidad de distancias en este deporte, obliga a realizar d...

REPEATED SPRINT ABILITY IN PROFESSIONAL SOCCER vs. PROFESSIONAL FUTSAL PLAYERS [Capacidad de realizar esprints repetidos en jugadores profesionales de fútbol vs. Fútbol sala

Directory of Open Access Journals (Sweden)

V. Cuadrado-Peñafiel

2014-10-01

Full Text Available Purpose: To investigate the changes through repeated explosive effort sequences (20+20-m sprint with change of direction, jumping, metabolic response (lactate, as well as the relationship between these variables and fitness qualities (strength and endurance in professional futsal and soccer players. Methods: Male players (n =30, Twelve futsal and twenty soccer players completed three testing sessions. In the first session was measured VO2max on a motorized treadmill. In the second session was measured counter movement jump (CMJ and full squat RM in Smith Machine. Finally, in the third session six repeated-explosive effort sequences (RES was performed. Results: Similar values of lower limbs strength, CMJ height, LAC after RSA test and VO2max (95,12 vs. 94,73; 34,5 vs. 35,9; 13,65 vs. 14,33; 62,78 vs. 62,95 soccer vs. futsal respectively and significant differences when are analysed the loss of performance in velocity (total and between three first and three last and vertical jump height (2,67 vs. 4,4**; 1,28 vs. 2,1*; 2,88 vs. 6,1**; 9,71 vs. 14,3* soccer vs. futsal respectively. Conclusions: Professional futsal and soccer obtain significant differences in speed and vertical jump height (CMJ loss despite having similar values in squat, oxygen consumption, lactate after RSA test and CMJ height. Issue that could be attributed to the characteristics of the sport. This suggests that the volume should be increased oriented ability to perform repeated sprint actions over other type of training aimed at improving aerobic capacity especially at professional level.

Changes in Sprint and Jump Performances After Traditional, Plyometric, and Combined Resistance Training in Male Youth Pre- and Post-Peak Height Velocity.

Science.gov (United States)

Lloyd, Rhodri S; Radnor, John M; De Ste Croix, Mark B A; Cronin, John B; Oliver, Jon L

2016-05-01

The purpose of this study was to compare the effectiveness of 6-week training interventions using different modes of resistance (traditional strength, plyometric, and combined training) on sprinting and jumping performances in boys before and after peak height velocity (PHV). Eighty school-aged boys were categorized into 2 maturity groups (pre- or post-PHV) and then randomly assigned to (a) plyometric training, (b) traditional strength training, (c) combined training, or (d) a control group. Experimental groups participated in twice-weekly training programs for 6 weeks. Acceleration, maximal running velocity, squat jump height, and reactive strength index data were collected pre- and postintervention. All training groups made significant gains in measures of sprinting and jumping irrespective of the mode of resistance training and maturity. Plyometric training elicited the greatest gains across all performance variables in pre-PHV children, whereas combined training was the most effective in eliciting change in all performance variables for the post-PHV cohort. Statistical analysis indicated that plyometric training produced greater changes in squat jump and acceleration performances in the pre-PHV group compared with the post-PHV cohort. All other training responses between pre- and post-PHV cohorts were not significant and not clinically meaningful. The study indicates that plyometric training might be more effective in eliciting short-term gains in jumping and sprinting in boys who are pre-PHV, whereas those who are post-PHV may benefit from the additive stimulus of combined training.

PRONOUNCED MUSCLE DEOXYGENATION DURING SUPRAMAXIMAL EXERCISE UNDER SIMULATED HYPOXIA IN SPRINT ATHLETES

Directory of Open Access Journals (Sweden)

Kazuo Oguri

2008-12-01

Full Text Available The purpose of this study was to determine whether acute hypoxia alters the deoxygenation level in vastus lateralis muscle during a 30 s Wingate test, and to compare the muscle deoxygenation level between sprint athletes and untrained men. Nine male track sprinters (athletic group, VO2max 62.5 ± 4.1 ml/kg/min and 9 healthy untrained men (untrained group, VO2max 49.9 ± 5.2 ml·kg-1·min-1 performed a 30 s Wingate test under simulated hypoxic (FIO2 = 0.164 and PIO2 = 114 mmHg and normoxic conditions. During the exercise, changes in oxygenated hemoglobin (OxyHb in the vastus lateralis were measured using near infrared continuous wave spectroscopy. Decline in OxyHb, that is muscle deoxygenation, was expressed as percent change from baseline. Percutaneous arterial oxygen saturation (SpO2, oxygen uptake (VO2, and ventilation (VE were measured continuously. In both groups, there was significantly greater muscle deoxygenation, lower SpO2, lower peakVO2, and higher peakVE during supramaximal exercise under hypoxia than under normoxia, but no differences in peak and mean power output during the exercise. Under hypoxia, the athletic group experienced significantly greater muscle deoxygenation, lower SpO2, greater decrement in peakVO2 and increment in peakVE during the exercise than the untrained group. When the athletic and untrained groups were pooled, the increment of muscle deoxygenation was strongly correlated with lowest SpO2 in the 30 s Wingate test under hypoxia. These results suggest that acute exposure to hypoxia causes a greater degree of peripheral muscle deoxygenation during supramaximal exercise, especially in sprint athletes, and this physiological response would be explained mainly by lower arterial oxygen saturation

Repeated Sprint Ability in Young Basketball Players (Part 2): The Chronic Effects of Multidirection and of One Change of Direction Are Comparable in Terms of Physiological and Performance Responses

OpenAIRE

Attene, Giuseppe; Nikolaidis, Pantelis T.; Bragazzi, Nicola L.; Dello Iacono, Antonio; Pizzolato, Fabio; Zagatto, Alessandro M.; Dal Pupo, Juliano; Oggianu, Marcello; Migliaccio, Gian M.; Mannucci Pacini, Elena; Padulo, Johnny

2016-01-01

The aim of this study was to examine the effects of a 5-week training program, consisting of repeated 30-m sprints, on two repeated sprint ability (RSA) test formats: one with one change of direction (RSA) and the other with multiple changes of direction (RSM). Thirty-six young male and female basketball players (age 16.1 ± 0.9 years), divided into two experimental groups, were tested for RSA, RSM, squat jump, counter-movement jump, and the Yo-Yo Intermittent Recovery-Level-1 (Yo-Yo IR1) test...

Community-driven development for computational biology at Sprints, Hackathons and Codefests.

Science.gov (United States)

Möller, Steffen; Afgan, Enis; Banck, Michael; Bonnal, Raoul J P; Booth, Timothy; Chilton, John; Cock, Peter J A; Gumbel, Markus; Harris, Nomi; Holland, Richard; Kalaš, Matúš; Kaján, László; Kibukawa, Eri; Powel, David R; Prins, Pjotr; Quinn, Jacqueline; Sallou, Olivier; Strozzi, Francesco; Seemann, Torsten; Sloggett, Clare; Soiland-Reyes, Stian; Spooner, William; Steinbiss, Sascha; Tille, Andreas; Travis, Anthony J; Guimera, Roman; Katayama, Toshiaki; Chapman, Brad A

2014-01-01

Computational biology comprises a wide range of technologies and approaches. Multiple technologies can be combined to create more powerful workflows if the individuals contributing the data or providing tools for its interpretation can find mutual understanding and consensus. Much conversation and joint investigation are required in order to identify and implement the best approaches. Traditionally, scientific conferences feature talks presenting novel technologies or insights, followed up by informal discussions during coffee breaks. In multi-institution collaborations, in order to reach agreement on implementation details or to transfer deeper insights in a technology and practical skills, a representative of one group typically visits the other. However, this does not scale well when the number of technologies or research groups is large. Conferences have responded to this issue by introducing Birds-of-a-Feather (BoF) sessions, which offer an opportunity for individuals with common interests to intensify their interaction. However, parallel BoF sessions often make it hard for participants to join multiple BoFs and find common ground between the different technologies, and BoFs are generally too short to allow time for participants to program together. This report summarises our experience with computational biology Codefests, Hackathons and Sprints, which are interactive developer meetings. They are structured to reduce the limitations of traditional scientific meetings described above by strengthening the interaction among peers and letting the participants determine the schedule and topics. These meetings are commonly run as loosely scheduled "unconferences" (self-organized identification of participants and topics for meetings) over at least two days, with early introductory talks to welcome and organize contributors, followed by intensive collaborative coding sessions. We summarise some prominent achievements of those meetings and describe differences in how

Biomechanical comparison of the double-push technique and the conventional skate skiing technique in cross-country sprint skiing.

Science.gov (United States)

Stöggl, Thomas; Müller, Erich; Lindinger, Stefan

2008-09-01

The aims of the study were to: (1) adapt the "double-push" technique from inline skating to cross-country skiing; (2) compare this new skiing technique with the conventional skate skiing cross-country technique; and (3) test the hypothesis that the double-push technique improves skiing speed in a short sprint. 13 elite skiers performed maximum-speed sprints over 100 m using the double-push skate skiing technique and using the conventional "V2" skate skiing technique. Pole and plantar forces, knee angle, cycle characteristics, and electromyography of nine lower body muscles were analysed. We found that the double-push technique could be successfully transferred to cross-country skiing, and that this new technique is faster than the conventional skate skiing technique. The double-push technique was 2.9 +/- 2.2% faster (P push technique had a longer cycle length and a lower cycle rate, and it was characterized by higher muscle activity, higher knee extension amplitudes and velocities, and higher peak foot forces, especially in the first phase of the push-off. Also, the foot was more loaded laterally in the double-push technique than in the conventional skate skiing technique.

Traditional vs. Sport-Specific Vertical Jump Tests: Reliability, Validity, and Relationship With the Legs Strength and Sprint Performance in Adult and Teen Soccer and Basketball Players.

Science.gov (United States)

Rodríguez-Rosell, David; Mora-Custodio, Ricardo; Franco-Márquez, Felipe; Yáñez-García, Juan M; González-Badillo, Juan J

2017-01-01

Rodríguez-Rosell, D, Mora-Custodio, R, Franco-Márquez, F, Yáñez-García, JM, González-Badillo, JJ. Traditional vs. sport-specific vertical jump tests: reliability, validity, and relationship with the legs strength and sprint performance in adult and teen soccer and basketball players. J Strength Cond Res 31(1): 196-206, 2017-The vertical jump is considered an essential motor skill in many team sports. Many protocols have been used to assess vertical jump ability. However, controversy regarding test selection still exists based on the reliability and specificity of the tests. The main aim of this study was to analyze the reliability and validity of 2 standardized (countermovement jump [CMJ] and Abalakov jump [AJ]) and 2 sport-specific (run-up with 2 [2-LEGS] or 1 leg [1-LEG] take-off jump) vertical jump tests, and their usefulness as predictors of sprint and strength performance for soccer (n = 127) and basketball (n = 59) players in 3 different categories (Under-15, Under-18, and Adults). Three attempts for each of the 4 jump tests were recorded. Twenty-meter sprint time and estimated 1 repetition maximum in full squat were also evaluated. All jump tests showed high intraclass correlation coefficients (0.969-0.995) and low coefficients of variation (1.54-4.82%), although 1-LEG was the jump test with the lowest absolute and relative reliability. All selected jump tests were significantly correlated (r = 0.580-0.983). Factor analysis resulted in the extraction of one principal component, which explained 82.90-95.79% of the variance of all jump tests. The 1-LEG test showed the lowest associations with sprint and strength performance. The results of this study suggest that CMJ and AJ are the most reliable tests for the estimation of explosive force in soccer and basketball players in different age categories.

DISTANCES TO DARK CLOUDS: COMPARING EXTINCTION DISTANCES TO MASER PARALLAX DISTANCES

International Nuclear Information System (INIS)

Foster, Jonathan B.; Jackson, James M.; Stead, Joseph J.; Hoare, Melvin G.; Benjamin, Robert A.

2012-01-01

We test two different methods of using near-infrared extinction to estimate distances to dark clouds in the first quadrant of the Galaxy using large near-infrared (Two Micron All Sky Survey and UKIRT Infrared Deep Sky Survey) surveys. Very long baseline interferometry parallax measurements of masers around massive young stars provide the most direct and bias-free measurement of the distance to these dark clouds. We compare the extinction distance estimates to these maser parallax distances. We also compare these distances to kinematic distances, including recent re-calibrations of the Galactic rotation curve. The extinction distance methods agree with the maser parallax distances (within the errors) between 66% and 100% of the time (depending on method and input survey) and between 85% and 100% of the time outside of the crowded Galactic center. Although the sample size is small, extinction distance methods reproduce maser parallax distances better than kinematic distances; furthermore, extinction distance methods do not suffer from the kinematic distance ambiguity. This validation gives us confidence that these extinction methods may be extended to additional dark clouds where maser parallaxes are not available.

Effects of Pre - Season Short - Term Daily Undulating Periodized Training on Muscle Strength and Sprint Performance of Under - 20 Soccer Players

Directory of Open Access Journals (Sweden)

Charles Ricardo L OPES

2015-06-01

Full Text Available The aim of this study was to evaluate the effects of daily undulating training periodization designed for maximal lower limb muscle strength and sprint performance in under - 20 soccer players. Twenty - four male athletes (age = 19.1 ± 1.2 yr; mass = 71.1 ± 6. 8 kg; height = 178.0 ± 0.1 cm participated in four weeks of a daily undulating periodized (DUP training soccer program. During the pre - and post - training periods the subjects performed a one repetition maximum (1 RM half back squat test and a 15 - meter s print. Significant training - induced changes were observed in sprint times (pre = 2.38 ± 0.01 s; post = 2.31 ± 0.02 s and 1 RM tests (pre = 107.0 ± 2.0 kg; post = 128.0 ± 2.2 kg. These results indicate that a DUP program is efficient in promoting positive neuromuscular adaptations in soccer players, even with a short - term preseason training period.

The Effects of a Single Whole-Body Cryotherapy Exposure on Physiological, Performance, and Perceptual Responses of Professional Academy Soccer Players After Repeated Sprint Exercise.

Science.gov (United States)

Russell, Mark; Birch, Jack; Love, Thomas; Cook, Christian J; Bracken, Richard M; Taylor, Tom; Swift, Eamon; Cockburn, Emma; Finn, Charlie; Cunningham, Daniel; Wilson, Laura; Kilduff, Liam P

2017-02-01

Russell, M, Birch, J, Love, T, Cook, CJ, Bracken, RM, Taylor, T, Swift, E, Cockburn, E, Finn, C, Cunningham, D, Wilson, L, and Kilduff, LP. The effects of a single whole-body cryotherapy exposure on physiological, performance, and perceptual responses of professional academy soccer players after repeated sprint exercise. J Strength Cond Res 31(2): 415-421, 2017-In professional youth soccer players, the physiological, performance, and perceptual effects of a single whole-body cryotherapy (WBC) session performed shortly after repeated sprint exercise were investigated. In a randomized, counterbalanced, and crossover design, 14 habituated English Premier League academy soccer players performed 15 × 30 m sprints (each followed by a 10 m forced deceleration) on 2 occasions. Within 20 minutes of exercise cessation, players entered a WBC chamber (Cryo: 30 seconds at -60° C, 120 seconds at -135° C) or remained seated (Con) indoors in temperate conditions (∼25° C). Blood and saliva samples, peak power output (countermovement jump), and perceptual indices of recovery and soreness were assessed pre-exercise and immediately, 2-hour and 24-hour postexercise. When compared with Con, a greater testosterone response was observed at 2-hour (+32.5 ± 32.3 pg·ml, +21%) and 24-hour (+50.4 ± 48.9 pg·ml, +28%) postexercise (both P = 0.002) in Cryo (trial × treatment interaction: P = 0.001). No between-trial differences were observed for other salivary (cortisol and testosterone/cortisol ratio), blood (lactate and creatine kinase), performance (peak power output), or perceptual (recovery or soreness) markers (all trial × treatment interactions: P > 0.05); all of which were influenced by exercise (time effects: all P ≤ 0.05). A single session of WBC performed within 20 minutes of repeated sprint exercise elevated testosterone concentrations for 24 hours but did not affect any other performance, physiological, or perceptual measurements taken. Although unclear, WBC may be

Testing EDM of Total Stations

Directory of Open Access Journals (Sweden)

Cirbus Ján

2001-03-01

Full Text Available The paper is devoted to testing electrooptical distance measuring devices (EDM built in total stations, than can be used for various tasks in the contemporary geodetic works. A rich market offer and availability of these universal measuring systems with satisfying distance range, excellent accuracy and other parameters, make total stations as dominant terrestrial geodetic instruments.For succesfully applying these instruments, above all for relliable distance measurements, the stability of the modulation frequency is the most important pre-condition. In the article, therefore, there are given some methods to verify the modulation frequency stability. In addition, some ways for determining the EDM distance constant and periodical corrections of the phase measuring unit are introduced for 4 types of EDM : LEICA 1700L, TOPCON GTS6A, TOPCON GTS2, C.ZEISS ELTA50. It were also investigated their possibilities for precise distance survey. Values of the determined constants and periodical corrections are presented in Tab. 2.Based on the investigation results of the 4 EDM types and using the values m obtained for different distances S, equations of the a posteriori standard deviations in form : m = (a+b.S were derived too.

Hot and Hypoxic Environments Inhibit Simulated Soccer Performance and Exacerbate Performance Decrements When Combined

Science.gov (United States)

Aldous, Jeffrey W. F.; Chrismas, Bryna C. R.; Akubat, Ibrahim; Dascombe, Ben; Abt, Grant; Taylor, Lee

2016-01-01

The effects of heat and/or hypoxia have been well-documented in match-play data. However, large match-to-match variation for key physical performance measures makes environmental inferences difficult to ascertain from soccer match-play. Therefore, the present study aims to investigate the hot (HOT), hypoxic (HYP), and hot-hypoxic (HH) mediated-decrements during a non-motorized treadmill based soccer-specific simulation. Twelve male University soccer players completed three familiarization sessions and four randomized crossover experimental trials of the intermittent Soccer Performance Test (iSPT) in normoxic-temperate (CON: 18°C 50% rH), HOT (30°C; 50% rH), HYP (1000 m; 18°C 50% rH), and HH (1000 m; 30°C; 50% rH). Physical performance and its performance decrements, body temperatures (rectal, skin, and estimated muscle temperature), heart rate (HR), arterial blood oxygen saturation (SaO2), perceived exertion, thermal sensation (TS), body mass changes, blood lactate, and plasma volume were all measured. Performance decrements were similar in HOT and HYP [Total Distance (−4%), High-speed distance (~−8%), and variable run distance (~−12%) covered] and exacerbated in HH [total distance (−9%), high-speed distance (−15%), and variable run distance (−15%)] compared to CON. Peak sprint speed, was 4% greater in HOT compared with CON and HYP and 7% greater in HH. Sprint distance covered was unchanged (p > 0.05) in HOT and HYP and only decreased in HH (−8%) compared with CON. Body mass (−2%), temperatures (+2–5%), and TS (+18%) were altered in HOT. Furthermore, SaO2 (−8%) and HR (+3%) were changed in HYP. Similar changes in body mass and temperatures, HR, TS, and SaO2 were evident in HH to HOT and HYP, however, blood lactate (p physical performance during iSPT. Future interventions should address the increases in TS and body temperatures, to attenuate these decrements on soccer performance. PMID:26793122

Iterative method to compute the Fermat points and Fermat distances of multiquarks

International Nuclear Information System (INIS)

Bicudo, P.; Cardoso, M.

2009-01-01

The multiquark confining potential is proportional to the total distance of the fundamental strings linking the quarks and antiquarks. We address the computation of the total string distance and of the Fermat points where the different strings meet. For a meson the distance is trivially the quark-antiquark distance. For a baryon the problem was solved geometrically from the onset by Fermat and by Torricelli, it can be determined just with a rule and a compass, and we briefly review it. However we also show that for tetraquarks, pentaquarks, hexaquarks, etc., the geometrical solution is much more complicated. Here we provide an iterative method, converging fast to the correct Fermat points and the total distances, relevant for the multiquark potentials.

Iterative method to compute the Fermat points and Fermat distances of multiquarks

Energy Technology Data Exchange (ETDEWEB)

Bicudo, P. [CFTP, Departamento de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)], E-mail: bicudo@ist.utl.pt; Cardoso, M. [CFTP, Departamento de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

2009-04-13

The multiquark confining potential is proportional to the total distance of the fundamental strings linking the quarks and antiquarks. We address the computation of the total string distance and of the Fermat points where the different strings meet. For a meson the distance is trivially the quark-antiquark distance. For a baryon the problem was solved geometrically from the onset by Fermat and by Torricelli, it can be determined just with a rule and a compass, and we briefly review it. However we also show that for tetraquarks, pentaquarks, hexaquarks, etc., the geometrical solution is much more complicated. Here we provide an iterative method, converging fast to the correct Fermat points and the total distances, relevant for the multiquark potentials.

Poorer Intermittent Sprints Performance in Ramadan-Fasted Muslim Footballers despite Controlling for Pre-Exercise Dietary Intake, Sleep and Training Load

Science.gov (United States)

Aziz, Abdul Rashid; Che Muhamad, Ahmad Munir; Roslan, Siti Raifana; Ghulam Mohamed, Nazirah; Singh, Rabindarjeet; Chia, Michael Yong Hwa

2017-01-01

This study examines the effects of Ramadan fasting on sprint performance during prolonged intermittent exercise in trained Muslim footballers, under controlled pre-exercise conditions. A within-group, cross-over study design with two non-fasted or Control trials performed before (i.e., CON1) and after (CON2) the Ramadan month, and with the Ramadan-fasted (RAM) trials performed within the Ramadan month. After familiarization, 14 players completed a modified 60-min (4 × 15-min exercise blocks interspersed with 3-min intervals) of the Loughborough Intermittent Shuttle Test (mLIST) of fixed speeds of walking, jogging, running, but with all-out effort sprints. During the interval periods, capillary blood glucose and blood lactate measures were taken, rectal and skin temperatures were recorded and maximal voluntary isometric contractions (MVIC) of the dominant leg and hand-grip were performed to provide some indication to the cause(s) of ‘fatigue’ during exercise. Players were provided with standardized 24-h pre-packed meals prior to all trials. Sleep hours were objectively assessed and perceived training loads were monitored and these were equivalent between RAM and CON trials. Sprint times throughout mLIST were significantly faster in both CON1 and CON2 as compared to RAM trials (all P performance in RAM was observed as early as during the first 15-min of the mLIST. Blood markers, MVIC and thermoregulatory results were not substantially different between both CON and RAM trials. In conclusion, despite similarities in dietary intake, sleeping hours and training loads between conditions, results still indicate that Ramadan fasting had an adverse effect on prolonged intermittent performance. Nocebo effects plays a dominant role during exercise in the Ramadan-fasted state. PMID:29910364

Poorer Intermittent Sprints Performance in Ramadan-Fasted Muslim Footballers despite Controlling for Pre-Exercise Dietary Intake, Sleep and Training Load

Directory of Open Access Journals (Sweden)

Abdul Rashid Aziz

2017-01-01

Full Text Available This study examines the effects of Ramadan fasting on sprint performance during prolonged intermittent exercise in trained Muslim footballers, under controlled pre-exercise conditions. A within-group, cross-over study design with two non-fasted or Control trials performed before (i.e., CON1 and after (CON2 the Ramadan month, and with the Ramadan-fasted (RAM trials performed within the Ramadan month. After familiarization, 14 players completed a modified 60-min (4 × 15-min exercise blocks interspersed with 3-min intervals of the Loughborough Intermittent Shuttle Test (mLIST of fixed speeds of walking, jogging, running, but with all-out effort sprints. During the interval periods, capillary blood glucose and blood lactate measures were taken, rectal and skin temperatures were recorded and maximal voluntary isometric contractions (MVIC of the dominant leg and hand-grip were performed to provide some indication to the cause(s of ‘fatigue’ during exercise. Players were provided with standardized 24-h pre-packed meals prior to all trials. Sleep hours were objectively assessed and perceived training loads were monitored and these were equivalent between RAM and CON trials. Sprint times throughout mLIST were significantly faster in both CON1 and CON2 as compared to RAM trials (all P < 0.017; d = small to moderate, and this poorer performance in RAM was observed as early as during the first 15-min of the mLIST. Blood markers, MVIC and thermoregulatory results were not substantially different between both CON and RAM trials. In conclusion, despite similarities in dietary intake, sleeping hours and training loads between conditions, results still indicate that Ramadan fasting had an adverse effect on prolonged intermittent performance. Nocebo effects plays a dominant role during exercise in the Ramadan-fasted state.

Periodization and physical performance in elite female soccer players.

Science.gov (United States)

Mara, Jocelyn K; Thompson, Kevin G; Pumpa, Kate L; Ball, Nick B

2015-07-01

To investigate the variation in training demands, physical performance, and player well-being across a women's soccer season. Seventeen elite female players wore GPS tracking devices during every training session (N=90) throughout 1 national-league season. Intermittent high-speed-running capacity and 5-, 15-, and 25-m-sprint testing were conducted at the beginning of preseason, end of preseason, midseason, and end of season. In addition, subjective well-being measures were self-reported daily by players over the course of the season. Time over 5 m was lowest at the end of preseason (mean 1.148 s, SE 0.017 s) but then progressively deteriorated to the end of the season (Pperformance over 15 m improved by 2.8% (P=.013) after preseason training, while 25-m-sprint performance peaked at midseason, with a 3.1% (P=.05) improvement from the start of preseason, before declining at the end of season (P=.023). Training demands varied between phases, with total distance and high-speed distance greatest during preseason before decreasing (Pphysical performance in elite female soccer players allow coaches to ensure that training periodization goals are being met and related positive training adaptations are being elicited.

Injury Prevention and Performance Optimization in Soldiers of the Army 101st Airborne/Air Assault Division

Science.gov (United States)

2011-04-01

understanding and familiarity. A rest period of at least 60 de- gree/seconds was given prior to each strength test. Reciprocal concentric isokinetic ...of approxi- mately 84 cm, and the height of a window or a wall and the depth of a ditch can be close to a meter or more. Moreover, the maximum VGRF...drills, and agility drills. Shuttle runs and sprints used a fun- nel design, with the volume (total distance) progressing from high (274 meters (m)) to

THE EFFECTS OF THREE DIFFERENT REAR KNEE ANGLES ON KINEMATICS IN THE SPRINT START

Directory of Open Access Journals (Sweden)

C. Milanese

2014-08-01

Full Text Available The purpose of this study was to investigate the rear knee angle range in the set position that allows sprinters to reach greater propulsion on the rear block during the sprint start. Eleven university-track team sprinters performed the sprint start using three rear knee angle conditions: 90°, 115° and 135°. A motion capture system consisting of 8 digital cameras (250 Hz was used to record kinematic parameters at the starting block phase and the acceleration phase. The following variables were considered: horizontal velocity of the centre of mass (COM, COM height, block time, pushing time on the rear block, percentage of pushing time on the rear block, force impulse, push-off angle and length of the first two strides. The main results show that first, horizontal block velocity is significantly greater at 90° vs 115° and 135° rear knee angle (p<0.05 and p<0.001 respectively at block clearance and the first two strides; second, during the pushing phase, the percentage of pushing time of the rear leg is significantly greater at 90° vs 135° rear knee angle (p<0.01. No significant difference was found for block time among the conditions. These results indicate that block velocity is the main kinematic parameter affected by rear knee angle during the starting block phase and acceleration phase. Furthermore, the 90° rear knee angle allows for a better push-off of the rear leg than larger angles at the set position. The findings of this study provide some direction and useful practical advice in defining an efficient rear leg biomechanical configuration at the set position.

Alterations to the orientation of the ground reaction force vector affect sprint acceleration performance in team sports athletes.

Science.gov (United States)

Bezodis, Neil E; North, Jamie S; Razavet, Jane L

2017-09-01

A more horizontally oriented ground reaction force vector is related to higher levels of sprint acceleration performance across a range of athletes. However, the effects of acute experimental alterations to the force vector orientation within athletes are unknown. Fifteen male team sports athletes completed maximal effort 10-m accelerations in three conditions following different verbal instructions intended to manipulate the force vector orientation. Ground reaction forces (GRFs) were collected from the step nearest 5-m and stance leg kinematics at touchdown were also analysed to understand specific kinematic features of touchdown technique which may influence the consequent force vector orientation. Magnitude-based inferences were used to compare findings between conditions. There was a likely more horizontally oriented ground reaction force vector and a likely lower peak vertical force in the control condition compared with the experimental conditions. 10-m sprint time was very likely quickest in the control condition which confirmed the importance of force vector orientation for acceleration performance on a within-athlete basis. The stance leg kinematics revealed that a more horizontally oriented force vector during stance was preceded at touchdown by a likely more dorsiflexed ankle, a likely more flexed knee, and a possibly or likely greater hip extension velocity.

The Physiological Mechanisms of Performance Enhancement with Sprint Interval Training Differ between the Upper and Lower Extremities in Humans

Science.gov (United States)

Zinner, Christoph; Morales-Alamo, David; Ørtenblad, Niels; Larsen, Filip J.; Schiffer, Tomas A.; Willis, Sarah J.; Gelabert-Rebato, Miriam; Perez-Valera, Mario; Boushel, Robert; Calbet, Jose A. L.; Holmberg, Hans-Christer

2016-01-01

To elucidate the mechanisms underlying the differences in adaptation of arm and leg muscles to sprint training, over a period of 11 days 16 untrained men performed six sessions of 4–6 × 30-s all-out sprints (SIT) with the legs and arms, separately, with a 1-h interval of recovery. Limb-specific VO2peak, sprint performance (two 30-s Wingate tests with 4-min recovery), muscle efficiency and time-trial performance (TT, 5-min all-out) were assessed and biopsies from the m. vastus lateralis and m. triceps brachii taken before and after training. VO2peak and Wmax increased 3–11% after training, with a more pronounced change in the arms (P training, VO2 during the two Wingate tests was increased by 52 and 6% for the arms and legs, respectively (P intensity, HR, VO2, VCO2, VE, and Vt were all lower during arm-cranking than leg-pedaling, and oxidation of fat was minimal, remaining so after training. Despite the higher relative intensity, fat oxidation was 70% greater during leg-pedaling (P = 0.017). The aerobic energy contribution in the legs was larger than for the arms during the Wingate tests, although VO2 for the arms was enhanced more by training, reducing the O2 deficit after SIT. The levels of muscle glycogen, as well as the myosin heavy chain composition were unchanged in both cases, while the activities of 3-hydroxyacyl-CoA-dehydrogenase and citrate synthase were elevated only in the legs and capillarization enhanced in both limbs. Multiple regression analysis demonstrated that the variables that predict TT performance differ for the arms and legs. The primary mechanism of adaptation to SIT by both the arms and legs is enhancement of aerobic energy production. However, with their higher proportion of fast muscle fibers, the arms exhibit greater plasticity. PMID:27746738

Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale

DEFF Research Database (Denmark)

Cao, Haichuan; Chen, Ruirui; Wang, Libing

2016-01-01

Considering the extensive functional redundancy in microbial communities and great difficulty in elucidating it based on taxonomic structure, studies on the biogeography of soil microbial activity at large spatial scale are as important as microbial community structure. Eighty-four soil samples...... scaling clearly revealed that soil microbial activities showed distinct differentiation at different sites over a regional spatial scale, which were strongly affected by soil pH, total P, rainfall, temperature, soil type and location. In addition, microbial community structure was greatly influenced...... scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity....

Open Science & Open Data Global Sprint 2016 | 2–3 June 2016

CERN Multimedia

Achintya Rao

2016-01-01

Join us as we learn to collaboratively build projects transforming science on the web! Thursday 2 June 2016 8.00 a.m. – Friday 3 June 20.00 p.m. CERN (3179-R-E06) This two-day sprint event brings together researchers, coders, librarians and the public from around the globe to hack on open science and open data projects in their communities. This year, we have four tracks you can contribute to: tools, citizen science, curriculum and open data. CERN is hosting three projects: Everware Open Cosmics CrowdAI   You can also participate in any of the other mozsprint projects for 2016. For more information, please visit: https://indico.cern.ch/event/535760/

A Short-Range Distance Sensor with Exceptional Linearity

Science.gov (United States)

Simmons, Steven; Youngquist, Robert

2013-01-01

A sensor has been demonstrated that can measure distance over a total range of about 300 microns to an accuracy of about 0.1 nm (resolution of about 0.01 nm). This represents an exceptionally large dynamic range of operation - over 1,000,000. The sensor is optical in nature, and requires the attachment of a mirror to the object whose distance is being measured. This work resulted from actively developing a white light interferometric system to be used to measure the depths of defects in the Space Shuttle Orbiter windows. The concept was then applied to measuring distance. The concept later expanded to include spectrometer calibration. In summary, broadband (i.e., white) light is launched into a Michelson interferometer, one mirror of which is fixed and one of which is attached to the object whose distance is to be measured. The light emerging from the interferometer has traveled one of two distances: either the distance to the fixed mirror and back, or the distance to the moving mirror and back. These two light beams mix and produce an interference pattern where some wavelengths interfere constructively and some destructively. Sending this light into a spectrometer allows this interference pattern to be analyzed, yielding the net distance difference between the two paths. The unique feature of this distance sensor is its ability to measure accurately distance over a dynamic range of more than one million, the ratio of its range (about 300 microns) to its accuracy (about 0.1 nanometer). Such a large linear operating range is rare and arises here because both amplitude and phase-matching algorithms contribute to the performance. The sensor is limited by the need to attach a mirror of some kind to the object being tracked, and by the fairly small total range, but the exceptional dynamic range should make it of interest.

Metabolic Responses and Pacing Strategies during Successive Sprint Skiing Time Trials

DEFF Research Database (Denmark)

Andersson, Erik; Holmberg, Hans-Christer; Ørtenblad, Niels

2016-01-01

PURPOSE: To examine the metabolic responses and pacing strategies during the performance of successive sprint time trials (STTs) in cross-country skiing. METHODS: Ten well-trained male cross-country skiers performed four self-paced 1300-m STTs on a treadmill, each separated by 45 min of recovery...... to estimate the anaerobic energy supply. RESULTS: The individual trial-to-trial variability in STT performance time was 1.3%, where variations in O2 deficit and V˙O2 explained 69% (P 0.05) of the variation in performance. The first and last STTs were equally fast (228 ± 10 s), and ~ 1...... on the first than second course half. In addition, metabolic rates were substantially higher (~_30%) for uphill than for flat skiing, indicating that pacing was regulated to the terrain. CONCLUSIONS: The fastest STTs were characterized primarily by a greater anaerobic energy production, which also explained 69...

Total body irradiation

International Nuclear Information System (INIS)

Novack, D.H.; Kiley, J.P.

1987-01-01

The multitude of papers and conferences in recent years on the use of very large megavoltage radiation fields indicates an increased interest in total body, hemibody, and total nodal radiotherapy for various clinical situations. These include high dose total body irradiation (TBI) to destroy the bone marrow and leukemic cells and provide immunosuppression prior to a bone marrow transplant, high dose total lymphoid irradiation (TLI) prior to bone marrow transplantation in severe aplastic anemia, low dose TBI in the treatment of lymphocytic leukemias or lymphomas, and hemibody irradiation (HBI) in the treatment of advanced multiple myeloma. Although accurate provision of a specific dose and the desired degree of dose homogeneity are two of the physicist's major considerations for all radiotherapy techniques, these tasks are even more demanding for large field radiotherapy. Because most large field radiotherapy is done at an extended distance for complex patient geometries, basic dosimetry data measured at the standard distance (isocenter) must be verified or supplemented. This paper discusses some of the special dosimetric problems of large field radiotherapy, with specific examples given of the dosimetry of the TBI program for bone marrow transplant at the authors' hospital

The Effect of High Intensity Intermittent Exercise on Power Output for the Upper Body

Directory of Open Access Journals (Sweden)

Leonie Harvey

2015-06-01

Full Text Available The aim of the present study was to examine and measure high intensity, intermittent upper body performance, in addition to identifying areas of the body that affect the variance in total work done during the 5 × 6 s sprint test. Fifteen males completed an upper body 5 × 6 s sprint test on a modified electro-magnetically braked cycle ergometer, which consisted of five maximal effort sprints, each 6 s in duration, separated by 24 s of passive recovery. A fly wheel braking force corresponding to 5% of the participants’ body weight was used as the implemented resistance level. Body composition was measured using dual-energy X-ray absorptiometry (DEXA. Percent (% decrement was calculated as 100 − (Total work/ideal work × 100. Significant (P < 0.05 differences were found between sprints for both absolute and relative (W, W·kg−1, W·kg−1 Lean body mass (LBM and W·kg−1 Upper body lean body mass (UBLBM peak (PP and mean (MP power. The % decrement in total work done over the five sprints was 11.4%. Stepwise multiple linear regression analysis revealed that UBLBM accounts for 87% of the variance in total work done during the upper body 5 × 6 s sprint test. These results provide a descriptive analysis of upper body, high intensity intermittent exercise, demonstrating that PP and MP output decreased significantly during the upper body 5 × 6 s sprint test.

Relationship Between Jumping Ability, Agility and Sprint Performance of Elite Young Basketball Players: A Field-Test Approach

OpenAIRE

Abbas Asadi

2016-01-01

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p177   The purpose of this study was to determine the relationships between sprint, agility and jump performance of elite young basketball players. Sixteen elite national level young male basketball players participated in this study. The jumping ability of each player was determined using countermovement jump (CMJ), and broad long jump (BLJ). The agility T test (TT) and Illinois agility test (IAT) were assessed to determine the agilit...

Long-distance mountain biking does not disturb the measurement of total, free or complexed prostate-specific antigen in healthy men.

Science.gov (United States)

Herrmann, Markus; Scharhag, Jürgen; Sand-Hill, Marga; Kindermann, Wilfried; Herrmann, Wolfgang

2004-03-01

Mechanical manipulation of the prostate is a generally accepted interfering factor for the measurement of prostate-specific antigen (PSA). However, only few studies have focused on common daily mechanical manipulations, such as bicycle riding. Furthermore, physical exercise is also supposed to modulate PSA serum concentration. Long-distance mountain biking is an excellent model to study the combined effect of mechanical prostate manipulation by bicycle riding and strenuous endurance exercise on total, free and complexed PSA (tPSA, fPSA, cPSA). We investigated tPSA, fPSA and cPSA in 42 healthy male cyclists (mean age 35+/-6 years) before and after a 120 km off-road mountain bike race. Blood sampling was done before, 15 min and 3 h after the race. Mean race time was 342+/-65 min. All athletes had normal serum levels of tPSA, fPSA or cPSA. None of these parameters was modified by the race. In healthy men the measurement of tPSA, fPSA and cPSA is not disturbed by preceding long distance mountain biking or endurance exercise. Based on the present data, there is no evidence for a recommendation to limit bicycle riding or physical activity before the measurement of tPSA, fPSA or cPSA.

Effects of In-Season Short-term Plyometric Training Program on Sprint and Jump Performance of Young Male Track Athletes.

Science.gov (United States)

Chelly, Mohamed Souhaiel; Hermassi, Souhail; Shephard, Roy J

2015-08-01

We studied the effect of supplementing normal in-season training by a 10-week lower limb plyometric training program (hurdle and depth jumping), examining measures of competitive potential (peak power output [PP], sprint running velocity, squat jump [SJ], countermovement jump [CMJ], drop jump [DJ], and lower limb muscle volume). The subjects (27 male track athletes, aged 11.9 ± 1.0 years; body mass: 39.1 ± 6.1 kg; height: 1.56 ± 0.02 m; body fat: 12.8 ± 4.4%) were randomly assigned between a control (normal training) group (C; n = 13) and an experimental group (E; n = 14) who also performed plyometric training 3 times per week. A force-velocity ergometer test determined PP and SJ, and an Optojump apparatus evaluated CMJ height and DJ (height and power). A multiple-5-bound test assessed horizontal jumping, and video-camera analyses over a 40-m sprint yielded velocities for the first step (VS), the first 5 m (V5m), and between 35 and 40 m (Vmax). Leg muscle volume was estimated anthropometrically. Experimental group showed gains relative to C in SJ height (p plyometric training improved important components of athletic performance relative to standard in-season training in young runners.

THE ROLE OF AEROBIC CAPACITY IN HIGH-INTENSITY INTERMITTENT EFFORTS IN ICE-HOCKEY

Directory of Open Access Journals (Sweden)

A. Stanula

2014-08-01

Full Text Available The primary objective of this study was to determine a relationship between aerobic capacity ( ·VO2max and fatigue from high-intensity skating in elite male hockey players. The subjects were twenty-four male members of the senior national ice hockey team of Poland who played the position of forward or defence. Each subject completed an on-ice Repeated-Skate Sprint test (RSS consisting of 6 timed 89-m sprints, with 30 s of rest between subsequent efforts, and an incremental test on a cycle ergometer in the laboratory, the aim of which was to establish their maximal oxygen uptake ( ·VO2max. The analysis of variance showed that each next repetition in the 6x89 m test was significantly longer than the previous one (F5,138=53.33, p<0.001. An analysis of the fatigue index (FI calculated from the times recorded for subsequent repetitions showed that the value of the FI increased with subsequent repetitions, reaching its maximum between repetitions 5 and 6 (3.10±1.16%. The total FI was 13.77±1.74%. The coefficient of correlation between ·VO2max and the total FI for 6 sprints on the distance of 89 m (r =–0.584 was significant (p=0.003. The variance in the index of players’ fatigue in the 6x89 m test accounted for 34% of the variance in ·VO2max. The 6x89 m test proposed in this study offers a high test-retest correlation coefficient (r=0.78. Even though the test is criticized for being too exhaustive and thereby for producing highly variable results it still seems that it was well selected for repeated sprint ability testing in hockey players.

A prosthesis-specific multi-link segment model of lower-limb amputee sprinting.

Science.gov (United States)

Rigney, Stacey M; Simmons, Anne; Kark, Lauren

2016-10-03

Lower-limb amputees commonly utilize non-articulating energy storage and return (ESAR) prostheses for high impact activities such as sprinting. Despite these prostheses lacking an articulating ankle joint, amputee gait analysis conventionally features a two-link segment model of the prosthetic foot. This paper investigated the effects of the selected link segment model׳s marker-set and geometry on a unilateral amputee sprinter׳s calculated lower-limb kinematics, kinetics and energetics. A total of five lower-limb models of the Ottobock ® 1E90 Sprinter were developed, including two conventional shank-foot models that each used a different version of the Plug-in-Gait (PiG) marker-set to test the effect of prosthesis ankle marker location. Two Hybrid prosthesis-specific models were then developed, also using the PiG marker-sets, with the anatomical shank and foot replaced by prosthesis-specific geometry separated into two segments. Finally, a Multi-link segment (MLS) model was developed, consisting of six segments for the prosthesis as defined by a custom marker-set. All full-body musculoskeletal models were tested using four trials of experimental marker trajectories within OpenSim 3.2 (Stanford, California, USA) to find the affected and unaffected hip, knee and ankle kinematics, kinetics and energetics. The geometry of the selected lower-limb prosthesis model was found to significantly affect all variables on the affected leg (p prosthesis-specific spatial, inertial and elastic properties from full-body models significantly affects the calculated amputee gait characteristics, and we therefore recommend the implementation of a MLS model. Copyright © 2016 Elsevier Ltd. All rights reserved.

The relationship between running speed and measures of vertical jump in professional basketball players: a field-test approach.

Science.gov (United States)

Shalfawi, Shaher A I; Sabbah, Ammar; Kailani, Ghazi; Tønnessen, Espen; Enoksen, Eystein

2011-11-01

The purpose of this study was to examine the relationship between vertical jump measures and sprint speed over 10, 20, and 40 m in professional basketball players. Thirty-three professional basketball players aged (±SD) (27.4 ± 3.3 years), body mass (89.8 ± 11.1 kg), and stature (192 ± 8.2 cm) volunteered to participate in this study. All participants were tested on squat jump, countermovement jump, and 40-m running speed. The results show that all jump measures in absolute terms were correlated significantly to running performance over 10-, 20-, and 40-m sprint times. None of the jumping performance peak powers and reactive strength were found to have a correlation to running speed times in absolute term. Furthermore, all jump height measures relative to body mass except reactive strength had a marked and significant relationship with all sprint performance times. The results of this study indicate that while there is a strong and marked relationship between 10-, 20-, and 40-m sprint, there is also a considerable variation within the factors that contribute to performance over these distances. This may indicate that, separate training strategies could be implemented to improve running speed over these distances.

Energy intake over 2 days is unaffected by acute sprint interval exercise despite increased appetite and energy expenditure.

Science.gov (United States)

Beaulieu, Kristine; Olver, T Dylan; Abbott, Kolten C; Lemon, Peter W R

2015-01-01

A cumulative effect of reduced energy intake, increased oxygen consumption, and/or increased lipid oxidation could explain the fat loss associated with sprint interval exercise training (SIT). This study assessed the effects of acute sprint interval exercise (SIE) on energy intake, subjective appetite, appetite-related peptides, oxygen consumption, and respiratory exchange ratio over 2 days. Eight men (25 ± 3 years, 79.6 ± 9.7 kg, body fat 13% ± 6%; mean ± SD) completed 2 experimental treatments: SIE and recovery (SIEx) and nonexercise control. Each 34-h treatment consisted of 2 consecutive 10-h test days. Between 0800-1800 h, participants remained in the laboratory for 8 breath-by-breath gas collections, 3 buffet-type meals, 14 appetite ratings, and 4 blood samples for appetite-related peptides. Treatment comparisons were made using 2-way repeated measures ANOVA or t tests. An immediate, albeit short-lived (SIEx (P SIEx (P = 0.04), elicited by the 1491-kJ (22%) greater energy expenditure over the first 24 h (P = 0.01). Despite its effects on oxygen consumption, appetite, and PYY, acute SIE did not affect energy intake. Consequently, if these dietary responses to SIE are sustained with regular SIT, augmentations in oxygen consumption and/or a substrate shift toward increased fat use postexercise are most likely responsible for the observed body fat loss with this type of exercise training.

A Combination of Amino Acids and Caffeine Enhances Sprint Running Capacity in a Hot, Hypoxic Environment.

Science.gov (United States)

Eaton, Tom R; Potter, Aaron; Billaut, François; Panchuk, Derek; Pyne, David B; Gore, Christopher J; Chen, Ting-Ting; McQuade, Leon; Stepto, Nigel K

2016-02-01

Heat and hypoxia exacerbate central nervous system (CNS) fatigue. We therefore investigated whether essential amino acid (EAA) and caffeine ingestion attenuates CNS fatigue in a simulated team sport-specific running protocol in a hot, hypoxic environment. Subelite male team sport athletes (n = 8) performed a repeat sprint running protocol on a nonmotorized treadmill in an extreme environment on 4 separate occasions. Participants ingested one of four supplements: a double placebo, 3 mg.kg-1 body mass of caffeine + placebo, 2 x 7 g EAA (Musashi Create)+placebo, or caffeine + EAA before each exercise session using a randomized, double-blind crossover design. Electromyography (EMG) activity and quadriceps evoked responses to magnetic stimulation were assessed from the dominant leg at preexercise, halftime, and postexercise. Central activation ratio (CAR) was used to quantify completeness of quadriceps activation. Oxygenation of the prefrontal cortex was measured via near-infrared spectroscopy. Mean sprint work was higher (M = 174 J, 95% CI [23, 324], p beneficial) in the caffeine + EAA condition versus EAAs alone. The decline in EMG activity was less (M = 13%, 95% CI [0, 26]; p beneficial) in caffeine + EAA versus EAA alone. Similarly, the pre- to postexercise decrement in CAR was significantly less (M = -2.7%, 95% CI [0.4, 5.4]; p beneficial) when caffeine + EAA were ingested compared with placebo. Cerebral oxygenation was lower (M = -5.6%, 95% CI [1.0, 10.1]; p beneficial) in the caffeine + EAA condition compared with LNAA alone. Co-ingestion of caffeine and EAA appears to maintain muscle activation and central drive, with a small improvement in running performance.

Bioenergetic constraints on tactical decision making in middle distance running.

Science.gov (United States)

Jones, A M; Whipp, B J

2002-04-01

The highest velocity that a runner can sustain during middle distance races is defined by the intersection of the runner's individual velocity-time curve and the distance-time curve. The velocity-time curve is presumably fixed at the onset of a race; however, whereas the race distance is ostensibly fixed, the actual distance-time curve is not. That is, it is possible for a runner to run further than the race distance if he or she runs wide on bends in track races. In this instance, the point of intersection of the individual velocity-time curve and the distance-time curve will move downwards and to the right, reducing the best average velocity that can be sustained for the distance. To illustrate this point, the race tactics used by the gold and silver medallists at 800 m and 5000 m in the Sydney Olympics were analysed. The paths taken by the runners were carefully tracked and the total distance they covered during the races and the average velocity they sustained over the distances they actually covered were calculated. In both the Olympic 800 m and 5000 m finals, for example, the winner was not the runner who ran at the highest average velocity in the race. Rather, the winners of these races were able to husband their metabolic resources to better effect by running closer to the actual race distance. Race results in middle distance running events are dependent not just on the energetic potential of the runners at the start of the race and their strategy for pace allocation, but also on the effect of their tactical approach to positioning on the total distance covered in the race. Middle distance runners should be conscious of minimising the distance covered in races if they wish to optimise their performance.

Locomotor activity, enjoyment and perceived exertion from 7v7 football for patients with Parkinson’s disease

DEFF Research Database (Denmark)

Møller, Trine Kjeldgaard Tang; Madsen, Mads; Frederiksen, Jakob

’s disease. Methods: 14 men from a football team for patients with Parkinson’s disease carried out a 1-h training session , during which heart rate (HR), accelerations, effort and distances (total, high intensity and sprints) was measured with ZXY radio wave based technology. The participants were 63±6 years...... on a 40x40 m artificial turf football pitch with 1.5x3 m goals. After each activity perceived exertion for lower limbs and total body individually was rated on a visual analogue scale (0-10). After the whole session the participants filled out a PACES questionnaire to rate enjoyment of the session. Height...

Seasonal Strength Performance and Its Relationship with Training Load on Elite Runners

Directory of Open Access Journals (Sweden)

Carlos Balsalobre-Fernández

2015-01-01

Full Text Available The aim of this study was to analyze the time-course of force production of elite middle and long-distance runners throughout an entire season and at the end of the off-season, as well as its relationships with training load and hormonal responses. Training load was recorded daily throughout an entire season by measuring and evaluating the session distance (km, training zone and session-RPE in a group of 15 elite middle and long-distance runners (12 men, 3 women; age = 26.3 ± 5.1yrs, BMI = 19.7 ± 1.1. Also, basal salivary-free cortisol levels were measured weekly, and 50-metre sprints, mean propulsive velocity (MPV, mean propulsive power (MPP, repetition maximum (RM and peak rate of force development (RFD of half-squats were measured 4 times during the season, and once more after the off-season break. There were no significant variations in force production during the season or after the off-season break, except for the RFD (-30.2%, p = 0.005 values, which changed significantly from the beginning to the end of the season. Significant correlations were found between session-RPE and MPV (r = -0.650, p = 0.004, MPP (r = -0.602, p = 0.009, RM (r = -0.650, p = 0.004, and the 50-metre sprint (r = 0.560, p = 0.015. Meanwhile, salivary-free cortisol correlated significantly with the 50-metre sprint (r = 0.737, p < 0.001 and the RM ( r = -0.514, p = 0.025. Finally, the training zone correlated with the 50-metre sprint (r = -0.463, p = 0.041. Session-RPE, training zone and salivary-free cortisol levels are related to force production in elite middle and long-distance runners. Monitoring these variables could be a useful tool in controlling the training programs of elite athletes.

Similar inflammatory responses following sprint interval training performed in hypoxia and normoxia

Directory of Open Access Journals (Sweden)

Alan James Richardson

2016-08-01

Full Text Available Sprint interval training (SIT is an efficient intervention capable of improving aerobic capacity and exercise performance. This experiment aimed to determine differences in training adaptations and the inflammatory responses following 2 weeks of SIT (30s maximal work, 4 min recovery; 4-7 repetitions performed in normoxia or hypoxia. Forty-two untrained participants [(mean ± SD, age 21 ±1 yrs, body mass 72.1 ±11.4 kg and height 173 ±10 cm] were equally and randomly assigned to one of three groups; control (CONT; no training, n = 14, normoxic (NORM; SIT in FiO2: 0.21, n = 14 and normobaric hypoxic (HYP; SIT in FiO2: 0.15, n = 14. Participants completed a V̇O2peak test, a time to exhaustion (TTE trial (power = 80% V̇O2peak and had haematological [haemoglobin (Hb, haematocrit (Hct] and inflammatory markers [interleukin-6 (IL-6, tumor necrosis factor-α (TNFα] measured in a resting state, pre and post SIT. V̇O2peak (mL.kg-1.min-1 improved in HYP (+11.9% and NORM (+9.8%, but not CON (+0.9%. Similarly TTE improved in HYP (+32.2% and NORM (+33.0%, but not CON (+3.4% whilst the power at the anaerobic threshold (AT; W.kg-1 also improved in HYP (+13.3% and NORM (+8.0%, but not CON (-0.3%. AT (mL.kg-1.min-1 improved in HYP (+9.5%, but not NORM (+5% or CON (-0.3%. No between group change occurred in 30 s sprint performance or Hb and Hct. IL-6 increased in HYP (+17.4% and NORM (+20.1%, but not CON (+1.2% respectively. TNF-α increased in HYP (+10.8% NORM (+12.9% and CON (+3.4%.SIT in HYP and NORM increased VO2peak, power at AT and TTE performance in untrained individuals, improvements in AT occurred only when SIT was performed in HYP. Increases in IL-6 and TNFα reflect a training induced inflammatory response to SIT; hypoxic conditions do not exacerbate this.

Physical and physiological demands of U-19 basketball refereeing: Aerobic and anaerobic demands.

Science.gov (United States)

Nabli, Mohamed Ali; Ben Abdelkrim, Nidhal; Castagna, Carlo; Jabri, Imed; Batikh, Tahar; Chamari, Karim

2016-01-01

This study aimed to examine the physical and physiological demands of basketball refereeing. 16 elite-level basketball referees were studied during U-19 basketball games (n=8) for time-motion analyses, exercise heart rates (HR) and blood lactate concentration [La]. Game activities were considered as time spent and distance covered in five locomotors activities (standing, walking, jogging, running and sprinting). Referees spent more time (pbasketball refereeing is a moderate intensity activity where referees spent 81% of total game time at low-intensity with bouts of high-intensity activities throughout the game.

The Relationship between Field Tests of Anaerobic Power and 10-km Run Performance.

Science.gov (United States)

Sinnett, Aaron M.; Berg, Kris; Latin, Richard W.; Noble, John M.

2001-01-01

Investigated the relationship between several field tests of anaerobic power (e.g., +various sprints, vertical jumps, and a plyometric leap) and distance running performance in trained adult male and female runners. Results indicate that anaerobic power is significantly related to distance running performance and may explain a meaningful…

The effect of milk on recovery from repeat-sprint cycling in female team-sport athletes.

Science.gov (United States)

Rankin, Paula; Lawlor, Michael J; Hills, Frank A; Bell, Phillip G; Stevenson, Emma J; Cockburn, Emma

2018-02-01

The consumption of milk following eccentric exercise attenuates the effects of muscle damage in team-sport athletes. However, participation in team sport involves both concentric-eccentric loading and metabolic stress. Therefore, the aim of this study was to investigate the effects of postexercise milk consumption on recovery from a cycling protocol designed to simulate the metabolic demands of team sport. Ten female team-sport athletes participated in a randomised crossover investigation. Upon completion of the protocol participants consumed 500 mL of milk (MILK) or 500 mL of an energy-matched carbohydrate (CHO) drink. Muscle function (peak torque, rate of force development, countermovement jump, 20-m sprint), muscle soreness and tiredness, serum creatine kinase, high-sensitivity C-reactive protein, and measures of oxidative stress (protein carbonyls and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio) were determined at pre-exercise and 24 h, 48 h, and 72 h postexercise. MILK had a possible beneficial effect in attenuating losses in peak torque (180°/s) from baseline to 24 h (3.2% ± 7.8% vs. -6.2% ± 7.5%, MILK vs. CHO) and a possible beneficial effect in minimising soreness (baseline-48 h; baseline-72 h) and tiredness (baseline-24 h; baseline-72 h). There was no change in oxidative stress following the exercise protocol, though a likely benefit of milk was observed for GSH/GSSG ratio at baseline-24 h (0.369 ×/÷ 1.89, 1.103 ×/÷ 3.96, MILK vs. CHO). MILK had an unclear effect on all other variables. Consumption of 500 mL of milk after repeat sprint cycling had little to no benefit in minimising losses in peak torque or minimising increases in soreness and tiredness and had no effect on serum markers of muscle damage and inflammation.

Comparison of efficiency of distance measurement methodologies in mango (Mangifera indica) progenies based on physicochemical descriptors.

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Alves, E O S; Cerqueira-Silva, C B M; Souza, A M; Santos, C A F; Lima Neto, F P; Corrêa, R X

2012-03-14

We investigated seven distance measures in a set of observations of physicochemical variables of mango (Mangifera indica) submitted to multivariate analyses (distance, projection and grouping). To estimate the distance measurements, five mango progeny (total of 25 genotypes) were analyzed, using six fruit physicochemical descriptors (fruit weight, equatorial diameter, longitudinal diameter, total soluble solids in °Brix, total titratable acidity, and pH). The distance measurements were compared by the Spearman correlation test, projection in two-dimensional space and grouping efficiency. The Spearman correlation coefficients between the seven distance measurements were, except for the Mahalanobis' generalized distance (0.41 ≤ rs ≤ 0.63), high and significant (rs ≥ 0.91; P < 0.001). Regardless of the origin of the distance matrix, the unweighted pair group method with arithmetic mean grouping method proved to be the most adequate. The various distance measurements and grouping methods gave different values for distortion (-116.5 ≤ D ≤ 74.5), cophenetic correlation (0.26 ≤ rc ≤ 0.76) and stress (-1.9 ≤ S ≤ 58.9). Choice of distance measurement and analysis methods influence the.

Run don't walk: locomotor performance of geckos on wet substrates.

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Stark, Alyssa Y; Ohlemacher, Jocelyn; Knight, Ashley; Niewiarowski, Peter H

2015-08-01

The gecko adhesive system has been under particular scrutiny for over a decade, as the field has recently attracted attention for its application to bio-inspired design. However, little is known about how the adhesive system behaves in ecologically relevant conditions. Geckos inhabit a variety of environments, many of which are characterized by high temperature, humidity and rain. The van der Waals-based gecko adhesive system should be particularly challenged by wet substrates because water can disrupt the intimate contact necessary for adhesion. While a few previous studies have focused on the clinging ability of geckos on wet substrates, we tested a dynamic performance characteristic, sprint velocity. To better understand how substrate wettability and running orientation affect locomotor performance of multiple species on wet substrates, we measured average sprint velocity of five species of gecko on substrates that were either hydrophilic or intermediately wetting and oriented either vertically or horizontally. Surprisingly, we found no indication that wet substrates impact average sprint velocity over 1 m, and rather, in some species, sprint velocity was increased on wet substrates rather than reduced. When investigating physical characteristics and behavior that may be associated with running on wet substrates, such as total number of stops, slips and wet toes at the completion of a race, we found that there may be habitat-related differences between some species. Our results show that in general, unlike clinging and walking, geckos running along wet substrates suffer no significant loss in locomotor performance over short distances. © 2015. Published by The Company of Biologists Ltd.

Improvements in Attention and Cardiac Autonomic Modulation After a 2-Weeks Sprint Interval Training Program: A Fidelity Approach

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Arilson F. M. de Sousa

2018-03-01

Full Text Available This study aimed to: (1 investigate the influence of a 2-weeks sprint interval training (SIT program on aerobic capacity, cardiac autonomic control, and components of attention in young healthy university students; and (2 to ascertain whether training fidelity would influence these adaptations. One hundred and nine participants were divided into an experimental (EG and control (CG groups. The EG performed a SIT program that consisted of 6 sessions of 4 × 30 s “all-out” efforts on a cycle ergometer, interspersed with active rests of 4 min. The criterion for fidelity was achieving >90% of estimated maximum heart rate (HR during sprint bouts. After analyses, the EG was divided into HIGH (n = 26 and LOW (n = 46 fidelity groups. Components of attention were assessed using the Attention Network Test (ANT. Aerobic capacity (VO2max was estimated while the sum of skinfolds was determined. Autonomic control of HR was assessed by means of HR variability (HRV and HR complexity at rest and during ANT. Both HIGH and LOW significantly increased aerobic capacity, vagal modulation before and during ANT, and executive control, and decreased body fatness after SIT (p < 0.05. However, only participants from HIGH showed an increase in HR complexity and accuracy in ANT when compared to LOW (p < 0.05. Two weeks of SIT improved executive control, body fatness, aerobic fitness, and autonomic control in university students with better results reported in those individuals who exhibited high fidelity.

Comparison of ergometer- and track-based testing in junior track-sprint cyclists. Implications for talent identification and development.

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Tofari, Paul J; Cormack, Stuart J; Ebert, Tammie R; Gardner, A Scott; Kemp, Justin G

2017-10-01

Talent identification (TID) and talent development (TDE) programmes in track sprint cycling use ergometer- and track-based tests to select junior athletes and assess their development. The purpose of this study was to assess which tests are best at monitoring TID and TDE. Ten male participants (16.2 ± 1.1 year; 178.5 ± 6.0 cm and 73.6 ± 7.6 kg) were selected into the national TID squad based on initial testing. These tests consisted of two 6-s maximal sprints on a custom-built ergometer and 4 maximal track-based tests (2 rolling and 2 standing starts) using 2 gear ratios. Magnitude-based inferences and correlation coefficients assessed changes following a 3-month TDE programme. Training elicited meaningful improvements (80-100% likely) in all ergometer parameters. The standing and rolling small gear, track-based effort times were likely and very likely (3.2 ± 2.4% and 3.3 ± 1.9%, respectively) improved by training. Stronger correlations between ergometer- and track-based measures were very likely following training. Ergometer-based testing provides a more sensitive tool than track-based testing to monitor changes in neuromuscular function during the early stages of TDE. However, track-based testing can indicate skill-based improvements in performance when interpreted with ergometer testing. In combination, these tests provide information on overall talent development.

The Effects of Sprint Interval vs. Continuous Endurance Training on Physiological and Metabolic Adaptations in Young Healthy Adults

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Nalcakan Gulbin Rudarli

2014-12-01

Full Text Available The purpose of this study was to compare the effects of sprint interval training (SIT and continuous endurance training (CET on selected anthropometric, aerobic, and anaerobic performance indices as well as the blood lipid profile, inflammatory and muscle damage markers in healthy young males. Fifteen recreationally active male volunteers (age: 21.7 ±2.2 years, body mass: 83.0 ±8.0 kg, body height: 1.82 ±0.05 m were divided into two groups according to their initial VO2max levels. Training programs were conducted 3 times per week for 7 weeks. The SIT program consisted of 4-6 Wingate anaerobic sprints with a 4.5 min recovery, while CET consisted of 30-50 min cycling at 60% VO2max. Biochemical, anthropometric and fitness assessments were performed both pre and post-intervention. Significant improvements in VO2max, anaerobic power and capacity, and VO2 utilization during the submaximal workout and significant decreases in body fat and in waist circumference after the intervention occurred in both SIT and CET groups. Significantly greater gross efficiency was measured in the CET group. No differences in the lipid profile or serum levels of inflammatory, myocardial and skeletal muscle damage markers were observed after the training period. The study results agree with the effectiveness of a 30 s all-out training program with a reduced time commitment for anthropometric, aerobic and anaerobic adaptation and eliminate doubts about its safety as a model.

Performance on Functional Strength Measurement and Muscle Power Sprint Test confirm poor anaerobic capacity in children with Developmental Coordination Disorder.

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Aertssen, Wendy F M; Ferguson, Gillian D; Smits-Engelsman, Bouwien C M

2016-12-01

There is little and conflicting information about anaerobic performance and functional strength in children with Developmental Coordination Disorder (DCD). To investigate anaerobic capacity and functional strength in children with a clinical diagnosis of DCD (clin-DCD) and if differences were larger in older (age 7-10 years) compared to younger children (age 4-6 years). Furthermore to determine the percentage of children with clin-DCD that scored Strength Measurement. A clin-DCD group (36 boys, 11 girls, mean age: 7y 1mo, SD=2y 1mo) and a typically developing group (TD) (57 boys, 53 girls, mean age: 7y 5mo, SD=1y 10mo) were compared on Muscle Power Sprint Test (MPST) and Functional Strength Measurement (FSM). Children with clin-DCD performed poorer on the MPST and FSM, especially on the muscle endurance items of the FSM. The differences were larger in the older children compared to the younger on the cluster muscle endurance and the FSM total score. Over 50% of clin-DCD group scored tested on items requiring fast repetitive movements. Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinematic characteristics of a sprinting technique and morphofunctional structures of its providing

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V. A. Druz

2017-02-01

2Kazimierz Wielki University in Bydgoszcz     Abstract Introduction The overall performance of a coach and the efficiency of performances of sportsmen are defined completely by the depth of understanding of regularities which are the cornerstone of the mechanisms, which provide the performance of competitive exercises. The most comprehensive investigations of these questions in track and field athletics are devoted to studying of sprint that significantly promoted the improvement of the process of a coach (Yefremenko, 2013 -2015; Shesterova, Yanhao, 2014-2016. However, the uniform generalization in the received scientific results isn't reached. It considerably reduces the overall performance of a coach. The optimization of the training process and the efficiency of performance of a sportsman are defined by the depth of knowledge of the interdependent relations of kinematic and dynamic characteristics of the performed physical actions and their connections with the morphofunctional educations, which provide their implementation. At the same time the final result depends on the motive endowments of a sportsman, the level of preparedness and the current functional state. The purpose of the research. To present the uniform system of the interdependent relations of the biomechanical and physiological regularities which provide the fastest movement of the general center of body weight GCBW of a sportsman when passing by him the established distance of run and to establish the structure of creation of an optimum algorithm of the training process taking into account individual physical development of a sportsman on the basis of provisions of the theory of training. The achievement of the purpose defined the need of the solution of the following tasks: 1. To carry out the analysis of literature and to systematize scientific achievements on the considered problem. 2. To select the fundamental laws of mechanics which define kinematic and dynamic characteristics of movement

EFFECTIVENESS OF LEARNING PROCESS USING “WEB TECHNOLOGY” IN THE DISTANCE LEARNING SYSTEM

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Manoj KILLEDAR

2008-10-01

Full Text Available Web is a globally distributed, still highly personalized media for cost-effective delivery of multimedia information and services. Web is expected to have a strong impact on almost every aspect of how we learn. ‘Total Quality’ is the totality of features, as perceived by the customers of the product or service. Totality of features includes stated as well as implied needs and expectations of all types of customers. No quality improvement is possible without its unambiguous measurement. But, ‘Total Quality’ of the learning experience in ‘Open and Distance Education System’ cannot be measured unless it is expressed in measurable clear terms which include complete spectrum of student support and educational services. A model for ‘Total Quality’ of an open and distance education system was used to measure impact of the “Web Technology” on the ‘Total Quality’ of the learning experience in ‘Open and Distance Education System’. Evidence indicates that application of the proposed model for ‘Total Quality’ and ‘Web Technology’ can simultaneously optimize quality, access and cost. Thus, a better learning experience can be provided even in open and distance education system, which can be comparable with the best. This study found that it was difficult for the subjects to decide the clear cut superiority regarding the effectiveness of ‘Traditional Classroom’ or ‘Virtual Classroom’.

The effect of ramadan fasting on physical performances, mood state and perceived exertion in young footballers.

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Chtourou, Hamdi; Hammouda, Omar; Souissi, Hichem; Chamari, Karim; Chaouachi, Anis; Souissi, Nizar

2011-09-01

This study was designed to assess the effects of Ramadan fasting on the profile of mood state and perceived exertion in young soccer players and aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests. Twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests on three different occasions: one-week before Ramadan (BR), the second week (SWR) and the fourth week (ER) of Ramadan. The total distance (TD) covered and the estimated maximal aerobic velocity (MAV) during the Yo-Yo test were recorded. During the RSA test, peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) were calculated. During the Wingate test, peak (P(peak)) and mean (P(mean)) powers and fatigue index (FI) were recorded. TD and MAV (P=0.01) during the Yo-Yo test and PP (P=0.01, P=0.004, P=0.001, P=0.01, P=0.03 for sprints 1, 2, 3, 4, and 5, respectively) and Wtotal (P=0.02) during the RSA test were significantly higher during BR than ER. Furthermore, muscle fatigue during the RSA test increased significantly from BR to ER (P=0.01). P(peak) and P(mean) during the Wingate test decreased significantly from BR to SWR and ER (PRamadan in comparison with BR. The present study suggests that both aerobic and anaerobic performances during the Yo-Yo, the RSA and the Wingate tests were affected by Ramadan fasting in young soccer players.

Monitoring Elite Soccer Players' External Loads Using Real-Time Data.

Science.gov (United States)

Barrett, Steve

2017-11-01

To assess the validity of measuring locomotor activities and PlayerLoad using real-time (RT) data collection during soccer training. Twenty-nine English soccer players participated. Each player wore the same MEMS device (Micromechanical Electrical Systems; S5, Optimeye; CatapultSports, Melbourne, Australia) during 21 training sessions (N = 331 data sets) in the 2015-16 and 2016-17 seasons. An RT receiver (TRX; Catapultsports, Melbourne, Australia) was used to collect the locomotor activities and PlayerLoad data in RT and compared with the postevent downloaded (PED) data. PlayerLoad and locomotor activities (total distance covered; total high-speed running distance covered, >5.5#x00A0;m/s; total sprinting distance covered, >7 m/s; maximum velocity) were analyzed. Correlations were near perfect for all variables analyzed (r = .98-1.00), with a varied level of noise between RT and PED also (0.3-9.7% coefficient of variation). Locomotor activities and PlayerLoad can use both RT and PED concurrently to quantify a player's physical output during a training session. Caution should be taken with higher-velocity-based locomotor activities during RT compared to PED.

The relationship between anogenital distance, fatherhood, and fertility in adult men.

Science.gov (United States)

Eisenberg, Michael L; Hsieh, Michael H; Walters, Rustin Chanc; Krasnow, Ross; Lipshultz, Larry I

2011-05-11

Anogenital distance (AGD), a sexually dimorphic measure of genital development, is a marker for endocrine disruption in animal studies and may be shorter in infant males with genital anomalies. Given the correlation between anogenital distance and genital development, we sought to determine if anogenital distance varied in fertile compared to infertile adult men. A cross sectional study of consecutive men being evaluated for infertility and men with proven fertility was recruited from an andrology clinic. Anogenital distance (the distance from the posterior aspect of the scrotum to the anal verge) and penile length (PL) were measured using digital calipers. ANOVA and linear regression were used to determine correlations between AGD, fatherhood status, and semen analysis parameters (sperm density, motility, and total motile sperm count). A total of 117 infertile men (mean age: 35.3±17.4) and 56 fertile men (mean age: 44.8±9.7) were recruited. The infertile men possessed significantly shorter mean AGD and PL compared to the fertile controls (AGD: 31.8 vs 44.6 mm, PL: 107.1 vs 119.5 mm, pfatherhood, on both unadjusted and adjusted linear regression, AGD was significantly correlated with sperm density and total motile sperm count. After adjusting for demographic and reproductive variables, for each 1 cm increase in a man's AGD, the sperm density increases by 4.3 million sperm per mL (95% CI 0.53, 8.09, p = 0.03) and the total motile sperm count increases by 6.0 million sperm (95% CI 1.34, 10.58, p = 0.01). On adjusted analyses, no correlation was seen between penile length and semen parameters. A longer anogenital distance is associated with fatherhood and may predict normal male reproductive potential. Thus, AGD may provide a novel metric to assess reproductive potential in men.

Peak oxygen uptake in a sprint interval testing protocol vs. maximal oxygen uptake in an incremental testing protocol and their relationship with cross-country mountain biking performance.

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Hebisz, Rafał; Hebisz, Paulina; Zatoń, Marek; Michalik, Kamil

2017-04-01

In the literature, the exercise capacity of cyclists is typically assessed using incremental and endurance exercise tests. The aim of the present study was to confirm whether peak oxygen uptake (V̇O 2peak ) attained in a sprint interval testing protocol correlates with cycling performance, and whether it corresponds to maximal oxygen uptake (V̇O 2max ) determined by an incremental testing protocol. A sample of 28 trained mountain bike cyclists executed 3 performance tests: (i) incremental testing protocol (ITP) in which the participant cycled to volitional exhaustion, (ii) sprint interval testing protocol (SITP) composed of four 30 s maximal intensity cycling bouts interspersed with 90 s recovery periods, (iii) competition in a simulated mountain biking race. Oxygen uptake, pulmonary ventilation, work, and power output were measured during the ITP and SITP with postexercise blood lactate and hydrogen ion concentrations collected. Race times were recorded. No significant inter-individual differences were observed in regards to any of the ITP-associated variables. However, 9 individuals presented significantly increased oxygen uptake, pulmonary ventilation, and work output in the SITP compared with the remaining cyclists. In addition, in this group of 9 cyclists, oxygen uptake in SITP was significantly higher than in ITP. After the simulated race, this group of 9 cyclists achieved significantly better competition times (99.5 ± 5.2 min) than the other cyclists (110.5 ± 6.7 min). We conclude that mountain bike cyclists who demonstrate higher peak oxygen uptake in a sprint interval testing protocol than maximal oxygen uptake attained in an incremental testing protocol demonstrate superior competitive performance.

The physiological mechanisms of performance enhancement with sprint interval training differ between the upper and lower extremities in humans.

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Christoph Zinner

2016-09-01

Full Text Available To elucidate the mechanisms underlying the differences in adaptation of arm and leg muscles to sprint training, over a period of 11 days 16 untrained men performed six sessions of 4-6x30-sec all-out sprints (SIT with the legs and arms, separately, with a 1-h interval of recovery. Limb-specific VO2peak, sprint performance (two 30-sec Wingate tests with 4-min recovery, muscle efficiency and time-trial performance (TT, 5-min all-out were assessed and biopsies from the m. vastus lateralis and m. triceps brachii taken before and after training. VO2peak and Wmax increased 3-11% after training, with a more pronounced change in the arms (P < 0.05. Gross efficiency improved for the arms (+8.8%, P < 0.05, but not the legs (-0.6%. Wingate peak and mean power outputs improved similarly for the arms and legs, as did TT performance. After training, VO2 during the two Wingate tests was increased by 52% and 6% for the arms and legs, respectively (P < 0.001. In the case of the arms, VO2 was higher during the first than second Wingate test (64% vs. 44%, P < 0.05. During the TT, relative exercise intensity, HR, VO2, VCO2, VE, and Vt were all lower during arm-cranking than leg-pedaling, and oxidation of fat was minimal, remaining so after training. Despite the higher relative intensity, fat oxidation was 70% greater during leg-pedaling (P = 0.017. The aerobic energy contribution in the legs was larger than for the arms during the Wingate tests, although VO2 for the arms was enhanced more by training, reducing the O2 deficit after SIT. The levels of muscle glycogen, as well as the myosin heavy chain composition were unchanged in both cases, while the activities of 3-hydroxyacyl-CoA-dehydrogenase and citrate synthase were elevated only in the legs and capillarization enhanced in both limbs. Multiple regression analysis demonstrated that the variables that predict TT performance differ for the arms and legs. The primary mechanism of adaptation to SIT by both the arms

Recovery benefits of using a heat and moisture exchange mask during sprint exercise in cold temperatures.

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Seifert, John G; Frost, Jeremy; St Cyr, John A

2017-01-01

Breathing cold air can lead to bronchoconstriction and peripheral vasoconstriction, both of which could impact muscular performance by affecting metabolic demands during exercise. Successful solutions dealing with these physiological changes during exercise in the cold has been lacking; therefore, we investigated the influence of a heat and moisture exchange mask during exercise in the cold. There were three trial arms within this study: wearing the heat and moisture exchange mask during the rest periods in the cold, no-mask application during the rest periods in the cold, and a trial at room temperature (22°C). Eight subjects cycled in four 35 kJ sprint sessions with each session separated by 20 min rest period. Workload was 4% of body mass. Mean sprint times were faster with heat and moisture exchange mask and room temperature trial than cold, no-mask trial (133.8 ± 8.6, 134.9 ± 8.8, and 138.0 ± 8.4 s (p = 0.001)). Systolic blood pressure and mean arterial pressure were greater during the cold trial with no mask (15% and 13%, respectively), and heart rate was 10 bpm less during the third rest or recovery period during cold, no mask compared to the heat and moisture exchange mask and room temperature trials. Subjects demonstrated significant decreases in vital capacity and peak expiratory flow rate during the cold with no mask applied during the rest periods. These negative responses to cold exposure were alleviated by the use of a heat and moisture exchange mask worn during the rest intervals by minimizing cold-induced temperature stress on the respiratory system with subsequent maintenance of cardiovascular function.

Acute and chronic effects of sprint interval exercise on postprandial lipemia in women at-risk for the metabolic syndrome.

Science.gov (United States)

Freese, Eric C; Gist, Nicholas H; Acitelli, Rachelle M; McConnell, Whitni J; Beck, Catherine D; Hausman, Dorothy B; Murrow, Jonathan R; Cureton, Kirk J; Evans, Ellen M

2015-04-01

Individuals diagnosed with the metabolic syndrome (MetS) exhibit elevated postprandial lipemia (PPL). The aims of this investigation were to determine 1) if an acute bout of sprint interval training (SIT) attenuates PPL; and 2) if the attenuation of PPL following 6 wk of SIT is magnified compared with a single session of SIT prior to training in women at-risk for MetS (n = 45; 30-65 yr). Women were randomized to SIT (n = 22) or a nonexercise control (n = 23; CON) for 6 wk. Postprandial responses to a high-fat meal challenge (HFMC) were assessed in the CON group before (B-HFMC) and after (Post-HFMC) without prior exercise and in the SIT group at baseline (B-HFMC) without prior exercise, after an acute bout of SIT (four 30-s all-out sprints with 4-min recovery) prior to (Pre-HFMC), and after the 6-wk intervention (Post-HFMC). Responses to the HFMC were assessed by collecting venous blood samples in the fasted state and at 0, 30, 60, 120, and 180 min postprandial. Compared with baseline, an acute bout of SIT before (Pre-HFMC) and after the 6-wk intervention (Post-HFMC) significantly attenuated fasted TG (P exercise to reduce fasted and postprandial TG concentrations in women at-risk for MetS. Six weeks of SIT does not magnify the attenuation of PPL in response to a single session of SIT. Copyright © 2015 the American Physiological Society.

Short-Term Effects of Combined High-Intensity Strength and Sprint Interval Training on Anthropometric Characteristics and Physical Performance of Elite Team Handball Players.

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Hermassi, Souhail; Chelly, Mohamed Souhail; Fieseler, Georg; Bartels, Thomas; Schulze, Stephan; Delank, Karl-Stefan; Shepard, Roy J; Schwesig, René

2017-12-01

Muscular strength and speed are critical physical factors in determining the technical and tactical skills of elite team handball players. This study thus investigated the effect of high-intensity muscular strength and sprint interval training (SIT) on lower limb explosive performance and anthropometric characteristics in 22 male handball athletes aged 20.2 ± 0.1 years. A training group (TG, n = 12) and a control group (CG, n = 10) were followed over 8 weeks parallel to regular handball training. The TG received combined additional high-intensity muscular strength and interval training twice per week during this period. The muscular training was comprised of 3 - 4 sets of 70 - 85 % of 1-RM (repetition maximum) of dynamic back half squat exercise; followed immediately by a short sprint program with 4, 5, and 6 maximal intensity repetitions of 30 m runs. Strength (1-RM of the half back-squat and bench press), first step (V1S), first 5 m (V5 m), squat jumps (SJ), counter movement jumps (CMJ) and the Modified Agility Test (MAT) were tested at the beginning and end of the study. Significant interaction effects (group × time) were observed for all parameters (η² range: 0.531 (MAT) to 0.829 (First 5 m)). All 10 parameters showed relevant intervention effects (d> 0.5) in the TG (highest intervention effect: CMJ: d = 4.05), the mean effect size being d = 1.85. In contrast, scores for the CG either remained unchanged or decreased (d = -0.24). We conclude that combined high-intensity strength and sprint interval training during the competitive season should be recommended to elite male handball players as a means of improving handball-related performance characteristics without compromising other critical aspects of the individual's performance. © Georg Thieme Verlag KG Stuttgart · New York.

Ecologically Valid Carbohydrate Intake during Soccer-Specific Exercise Does Not Affect Running Performance in a Fed State

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Mark P. Funnell

2017-01-01

Full Text Available This study assessed the effect of carbohydrate intake on self-selected soccer-specific running performance. Sixteen male soccer players (age 23 ± 4 years; body mass 76.9 ± 7.2 kg; predicted VO2max = 54.2 ± 2.9 mL∙kg−1∙min−1; soccer experience 13 ± 4 years completed a progressive multistage fitness test, familiarisation trial and two experimental trials, involving a modified version of the Loughborough Intermittent Shuttle Test (LIST to simulate a soccer match in a fed state. Subjects completed six 15 min blocks (two halves of 45 min of intermittent shuttle running, with a 15-min half-time. Blocks 3 and 6, allowed self-selection of running speeds and sprint times, were assessed throughout. Subjects consumed 250 mL of either a 12% carbohydrate solution (CHO or a non-caloric taste matched placebo (PLA before and at half-time of the LIST. Sprint times were not different between trials (CHO 2.71 ± 0.15 s, PLA 2.70 ± 0.14 s; p = 0.202. Total distance covered in self-selected blocks (block 3: CHO 2.07 ± 0.06 km; PLA 2.09 ± 0.08 km; block 6: CHO 2.04 ± 0.09 km; PLA 2.06 ± 0.08 km; p = 0.122 was not different between trials. There was no difference between trials for distance covered (p ≥ 0.297 or mean speed (p ≥ 0.172 for jogging or cruising. Blood glucose concentration was greater (p < 0.001 at the end of half-time during the CHO trial. In conclusion, consumption of 250 mL of 12% CHO solution before and at half-time of a simulated soccer match does not affect self-selected running or sprint performance in a fed state.

A Total Factor Productivity Toolbox for MATLAB

NARCIS (Netherlands)

B.M. Balk (Bert); J. Barbero (Javier); J.L. Zofío (José)

2018-01-01

textabstractTotal Factor Productivity Toolbox is a new package for MATLAB that includes functions to calculate the main Total Factor Productivity (TFP) indices and their decompositions, based on Shephard’s distance functions and using Data Envelopment Analysis (DEA) programming techniques. The

PERBANDINGAN EUCLIDEAN DISTANCE DENGAN CANBERRA DISTANCE PADA FACE RECOGNITION

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Sendhy Rachmat Wurdianarto

2014-08-01

Full Text Available Perkembangan ilmu pada dunia komputer sangatlah pesat. Salah satu yang menandai hal ini adalah ilmu komputer telah merambah pada dunia biometrik. Arti biometrik sendiri adalah karakter-karakter manusia yang dapat digunakan untuk membedakan antara orang yang satu dengan yang lainnya. Salah satu pemanfaatan karakter / organ tubuh pada setiap manusia yang digunakan untuk identifikasi (pengenalan adalah dengan memanfaatkan wajah. Dari permasalahan diatas dalam pengenalan lebih tentang aplikasi Matlab pada Face Recognation menggunakan metode Euclidean Distance dan Canberra Distance. Model pengembangan aplikasi yang digunakan adalah model waterfall. Model waterfall beriisi rangkaian aktivitas proses yang disajikan dalam proses analisa kebutuhan, desain menggunakan UML (Unified Modeling Language, inputan objek gambar diproses menggunakan Euclidean Distance dan Canberra Distance. Kesimpulan yang dapat ditarik adalah aplikasi face Recognation menggunakan metode euclidean Distance dan Canverra Distance terdapat kelebihan dan kekurangan masing-masing. Untuk kedepannya aplikasi tersebut dapat dikembangkan dengan menggunakan objek berupa video ataupun objek lainnya.   Kata kunci : Euclidean Distance, Face Recognition, Biometrik, Canberra Distance

Muscle metabolism of professional athletes using 31P-spectroscopy

International Nuclear Information System (INIS)

Maeurer, J.; Soellner, O.; Ehrenstein, T.; Knollmann, F.; Vogl, T.J.; Felix, R.; Konstanczak, P.; Wolff, R.

1999-01-01

Purpose: The aim of the study was to examine muscle metabolism in athletes by 31 P-spectroscopy (MRS) and to evaluate to what degree the respective resonance spectrum correlates with the kind of muscle exercise. Material and Methods: Twelve runners and 12 young ice skaters were studied by 31 P-spectroscopy of the gastrocnemic medialis muscle and the vastus medialis muscle using a surface coil at 1.5 T. Results: Sprinters displayed a higher phosphocreatinine/inorganic phosphate (PCr/Pi) and PCr/β-ATP ratios than marathon runners. The respective parameters for middle distance runners were in between. Ice skaters could prospectively be divided into sprint- and long-distance runners by our results which correlated with the athletes' training performance. Conclusion: 31 P-spectroscopy can evaluate the distribution of muscle fiber types. Thus, the athlete's potential for sprint- or long-distance running can be determined. Additional studies will have to demonstrate to what extent training may change muscle fiber distribution. (orig.)

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility.

Science.gov (United States)

Wong, Del P; Chaouachi, Anis; Lau, Patrick W C; Behm, David G

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key pointsThe duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001).No significant differences in RSA and COD between the 3 stretching conditions.The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects.The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility

Science.gov (United States)

Wong, Del P.; Chaouachi, Anis; Lau, Patrick W.C.; Behm, David G.

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key points The duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). No significant differences in RSA and COD between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. PMID:24149890

Foam Rolling for Delayed-Onset Muscle Soreness and Recovery of Dynamic Performance Measures

Science.gov (United States)

Pearcey, Gregory E. P.; Bradbury-Squires, David J.; Kawamoto, Jon-Erik; Drinkwater, Eric J.; Behm, David G.; Button, Duane C.

2015-01-01

Context: After an intense bout of exercise, foam rolling is thought to alleviate muscle fatigue and soreness (ie, delayed-onset muscle soreness [DOMS]) and improve muscular performance. Potentially, foam rolling may be an effective therapeutic modality to reduce DOMS while enhancing the recovery of muscular performance. Objective: To examine the effects of foam rolling as a recovery tool after an intense exercise protocol through assessment of pressure-pain threshold, sprint time, change-of-direction speed, power, and dynamic strength-endurance. Design: Controlled laboratory study. Setting: University laboratory. Patients or Other Participants: A total of 8 healthy, physically active males (age = 22.1 ± 2.5 years, height = 177.0 ± 7.5 cm, mass = 88.4 ± 11.4 kg) participated. Intervention(s): Participants performed 2 conditions, separated by 4 weeks, involving 10 sets of 10 repetitions of back squats at 60% of their 1-repetition maximum, followed by either no foam rolling or 20 minutes of foam rolling immediately, 24, and 48 hours postexercise. Main Outcome Measure(s): Pressure-pain threshold, sprint speed (30-m sprint time), power (broad-jump distance), change-of-direction speed (T-test), and dynamic strength-endurance. Results: Foam rolling substantially improved quadriceps muscle tenderness by a moderate to large amount in the days after fatigue (Cohen d range, 0.59 to 0.84). Substantial effects ranged from small to large in sprint time (Cohen d range, 0.68 to 0.77), power (Cohen d range, 0.48 to 0.87), and dynamic strength-endurance (Cohen d = 0.54). Conclusions: Foam rolling effectively reduced DOMS and associated decrements in most dynamic performance measures. PMID:25415413

The relationship between anogenital distance, fatherhood, and fertility in adult men.

Directory of Open Access Journals (Sweden)

Michael L Eisenberg

Full Text Available BACKGROUND: Anogenital distance (AGD, a sexually dimorphic measure of genital development, is a marker for endocrine disruption in animal studies and may be shorter in infant males with genital anomalies. Given the correlation between anogenital distance and genital development, we sought to determine if anogenital distance varied in fertile compared to infertile adult men. METHODS: A cross sectional study of consecutive men being evaluated for infertility and men with proven fertility was recruited from an andrology clinic. Anogenital distance (the distance from the posterior aspect of the scrotum to the anal verge and penile length (PL were measured using digital calipers. ANOVA and linear regression were used to determine correlations between AGD, fatherhood status, and semen analysis parameters (sperm density, motility, and total motile sperm count. FINDINGS: A total of 117 infertile men (mean age: 35.3±17.4 and 56 fertile men (mean age: 44.8±9.7 were recruited. The infertile men possessed significantly shorter mean AGD and PL compared to the fertile controls (AGD: 31.8 vs 44.6 mm, PL: 107.1 vs 119.5 mm, p<0.01. The difference in AGD persisted even after accounting for ethnic and anthropomorphic differences. In addition to fatherhood, on both unadjusted and adjusted linear regression, AGD was significantly correlated with sperm density and total motile sperm count. After adjusting for demographic and reproductive variables, for each 1 cm increase in a man's AGD, the sperm density increases by 4.3 million sperm per mL (95% CI 0.53, 8.09, p = 0.03 and the total motile sperm count increases by 6.0 million sperm (95% CI 1.34, 10.58, p = 0.01. On adjusted analyses, no correlation was seen between penile length and semen parameters. CONCLUSION: A longer anogenital distance is associated with fatherhood and may predict normal male reproductive potential. Thus, AGD may provide a novel metric to assess reproductive potential in men.

Position-Specific Acceleration and Deceleration Profiles in Elite Youth and Senior Soccer Players.

Science.gov (United States)

Vigh-Larsen, Jeppe F; Dalgas, Ulrik; Andersen, Thomas B

2018-04-01

Vigh-Larsen, JF, Dalgas, U, and Andersen, TB. Position-specific acceleration and deceleration profiles in elite youth and senior soccer players. J Strength Cond Res 32(4): 1114-1122, 2018-The purpose of the study was to characterize and compare the position-specific activity profiles of young and senior elite soccer players with special emphasis put on accelerations and decelerations. Eight professional senior matches were tracked using the ZXY tracking system and analyzed for the number of accelerations and decelerations and running distances within different speed zones. Likewise, 4 U19 and 5 U17 matches were analyzed for comparison between youth and senior players. In senior players, the total distance (TD) was 10,776 ± 107 m with 668 ± 28 and 143 ± 10 m being high-intensity running (HIR) and sprinting, respectively. Number of accelerations and decelerations were 81 ± 2 and 84 ± 3, respectively, with central defenders performing the lowest and wide players the highest number. Declines were found between first and second halves for accelerations and decelerations (11 ± 3%), HIR (6 ± 4%), and TD (5 ± 1%), whereas sprinting distance did not differ. U19 players performed a higher number of accelerations, decelerations, and TD compared with senior players. In conclusion, differences in the number and distribution of accelerations and decelerations appeared between player positions, which is of importance when monitoring training and match loads and when prescribing specific training exercises. Furthermore, youth players performed as much high-intensity activities as senior players, indicating that this is not a discriminating physiological parameter between these players.

Reliability and accuracy of Cooper's test in male long distance runners

OpenAIRE

J.R. Alvero-Cruz; M.A. Giráldez García; E.A. Carnero

2017-01-01

Objective: Endurance capacity can be assessed by field test such as Cooper's test; however, reliability and accuracy are rarely reported in the literature. It was our aims to describe reliability and accuracy of Cooper's test in long distance runners. Method: Fifteen male long distance runners performed twice all-out Cooper's test in a 400 m track. Total distance covered, maximum heart rate (HR) and rate of perceived exertion were recorded. Bias correction factor (Bc) was used to describe ...

The Progression of Male 100 m Sprinting with a Lower-Limb Amputation 1976–2012

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Bryce Dyer

2015-02-01

Full Text Available Sprinting with a lower-limb amputation over 100 m has taken place in the Paralympic Games for over three decades. The aim of this paper is to statistically evaluate the performances and participation levels of such athletes during this period. The level of performance improvement over a 36-year period was proposed to be significantly greater than the able-bodied equivalent. Coupled with this, a major spike in amputee running performance improvement was shown to occur from 1984–1988. This supports previously recorded accounts of a major technological change being made at this time. Finally, whilst the average performance of the medallists has increased consistently over the 36-year history, the overall participation in the event fell significantly after 1988 and did not recover until 2012.

Physical Demands of Top-Class Soccer Friendly Matches in Relation to a Playing Position Using Global Positioning System Technology.

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Mallo, Javier; Mena, Esteban; Nevado, Fabio; Paredes, Víctor

2015-09-29

The aim of this study was to examine the physical demands imposed on professional soccer players during 11-a-side friendly matches in relation to their playing position, using global positioning system (GPS) technology. One hundred and eleven match performances of a Spanish "La Liga" team during the 2010-11 and 2011-12 pre-seasons were selected for analysis. The activities of the players were monitored using GPS technology with a sampling frequency of 1 Hz. Total distance covered, distance in different speed categories, accelerations, and heart rate responses were analyzed in relation to five different playing positions: central defenders (n=23), full-backs (n=20), central midfielders (n=22), wide midfielders (n=26), and forwards (n=20). Distance covered during a match averaged 10.8 km, with wide and central midfielders covering the greatest total distance. Specifically, wide midfielders covered the greatest distances by very high-intensity running (>19.8 km·h-1) and central midfielders by jogging and running (7.2-19.7 km·h-1). On the other hand, central defenders covered the least total distance and at high intensity, although carried out more (pwork rate profile of the players obtained with the GPS was very similar to that obtained with semi-automatic image technologies. However, when comparing results from this study with data available in the literature, important differences were detected in the amount of distance covered by sprinting, which suggests that caution should be taken when comparing data obtained with the GPS with other motion analysis systems, especially regarding high-intensity activities.

Encyclopedia of distances

CERN Document Server

Deza, Michel Marie

2016-01-01

This 4th edition of the leading reference volume on distance metrics is characterized by updated and rewritten sections on some items suggested by experts and readers, as well a general streamlining of content and the addition of essential new topics. Though the structure remains unchanged, the new edition also explores recent advances in the use of distances and metrics for e.g. generalized distances, probability theory, graph theory, coding theory, data analysis. New topics in the purely mathematical sections include e.g. the Vitanyi multiset-metric, algebraic point-conic distance, triangular ratio metric, Rossi-Hamming metric, Taneja distance, spectral semimetric between graphs, channel metrization, and Maryland bridge distance. The multidisciplinary sections have also been supplemented with new topics, including: dynamic time wrapping distance, memory distance, allometry, atmospheric depth, elliptic orbit distance, VLBI distance measurements, the astronomical system of units, and walkability distance. Lea...

Effect of increasing energy cost on arm coordination in elite sprint swimmers.

Science.gov (United States)

Komar, J; Leprêtre, P M; Alberty, M; Vantorre, J; Fernandes, R J; Hellard, P; Chollet, D; Seifert, L

2012-06-01

The purpose of this study was to analyze the changes in stroke parameters, motor organization and swimming efficiency with increasing energy cost in aquatic locomotion. Seven elite sprint swimmers performed a 6×300-m incremental swimming test. Stroke parameters (speed, stroke rate and stroke length), motor organization (arm stroke phases and arm coordination index), swimming efficiency (swimming speed squared and hand speed squared) and stroke index were calculated from aerial and underwater side-view cameras. The energy cost of locomotion was assessed by measuring oxygen consumption and blood lactate. Results showed that the increase in energy cost of locomotion was correlated to an increase in the index of coordination and stroke rate, and a decrease in stroke length (pstroke index did not change significantly with the speed increments (pstroke rate were observed, along with a decrease in stroke length, stroke index and hand speed squared with each increment, revealing an adaptation to the fatigue within the 300m. Copyright © 2011 Elsevier B.V. All rights reserved.

Distance Learning

National Research Council Canada - National Science Library

Braddock, Joseph

1997-01-01

A study reviewing the existing Army Distance Learning Plan (ADLP) and current Distance Learning practices, with a focus on the Army's training and educational challenges and the benefits of applying Distance Learning techniques...

Plyometric Training Improves Sprinting, Jumping and Throwing Capacities of High Level Female Volleyball Players Better Than Skill-Based Conditioning

Science.gov (United States)

Gjinovci, Bahri; Idrizovic, Kemal; Uljevic, Ognjen; Sekulic, Damir

2017-01-01

There is an evident lack of studies on the effectiveness of plyometric- and skill-based-conditioning in volleyball. This study aimed to evaluate effects of 12-week plyometric- and volleyball-skill-based training on specific conditioning abilities in female volleyball players. The sample included 41 high-level female volleyball players (21.8 ± 2.1 years of age; 1.76 ± 0.06 cm; 60.8 ± 7.0 kg), who participated in plyometric- (n = 21), or skill-based-conditioning-program (n = 20). Both programs were performed twice per week. Participants were tested on body-height, body-mass (BM), countermovement jump (CMJ), standing broad jump (SBJ), medicine ball throw, (MBT) and 20-m sprint (S20M). All tests were assessed at the study baseline (pre-) and at the end of the 12-week programs (post-testing). Two-way ANOVA for repeated measurements showed significant (pvolleyball players. Future studies should evaluate differential program effects in less experienced and younger players. Key points Plyometric- and skill-based-conditioning resulted in improvements in jumping and throwing capacities, but plyometric training additionally induced positive changes in anthropometrics and sprint-capacity The changes induced by plyometric training were larger in magnitude than those achieved by skill-based conditioning. The higher intensity together with possibility of more accurate adjustment of training load in plyometric training are probably the most important determinant of such differential influence. It is likely that the skill-based conditioning program did not result in changes of higher magnitude because of the players’ familiarity with volleyball-related skills. PMID:29238253

INVESTIGATING OF THE RELATIONSHIP BETWEEN SPRINT AND JUMP PERFORMANCE WITH POWER PARAMETERS DURING PROPULSIVE PHASE OF FULL BACK SQUAT EXERCISE

OpenAIRE

İbrahim; Hamit

2015-01-01

The basic purpose of this study was to investigate of the relationships with sprint and jump performance of power parameters during propulsive phase of full back squat exercise and to determine which variable was associated with which loading loading. For this purpose, thirty-two men amateur athletes (age: 20.4 ± 1.98 years; height: 179.3 ± 7.23 cm; weight: 73.5 ± 9.85 kg) who actively involved in sports and have a basic level of force participated in voluntarily to this study. In the study, ...

A comparison of base running start techniques in collegiate fastpitch softball athletes

OpenAIRE

Massey, Kelly P.; Brouillette, Kelly Miller; Martino, Mike

2018-01-01

This study examined the time difference between three different base running start techniques. Thirteen Division II collegiate softball players performed maximal sprints off a softball bag at two different distances. Sprint times at 4.57 and 18.29 meters for each technique were measured using Fusion Sport’s Smartspeed System. At both 4.57 and 18.29 meters, the rocking start (0.84 ± 0.10; 3.04 ± 0.16 s) was found to be significantly faster (in seconds) than both the split technique (1.01 ± 0.0...

Sprint running: how changes in step frequency affect running mechanics and leg spring behaviour at maximal speed.

Science.gov (United States)

Monte, Andrea; Muollo, Valentina; Nardello, Francesca; Zamparo, Paola

2017-02-01

The purpose of this study was to investigate the changes in selected biomechanical variables in 80-m maximal sprint runs while imposing changes in step frequency (SF) and to investigate if these adaptations differ based on gender and training level. A total of 40 athletes (10 elite men and 10 women, 10 intermediate men and 10 women) participated in this study; they were requested to perform 5 trials at maximal running speed (RS): at the self-selected frequency (SF s ) and at SF ±15% and ±30%SF s . Contact time (CT) and flight time (FT) as well as step length (SL) decreased with increasing SF, while k vert increased with it. At SF s , k leg was the lowest (a 20% decrease at ±30%SF s ), while RS was the largest (a 12% decrease at ±30%SF s ). Only small changes (1.5%) in maximal vertical force (F max ) were observed as a function of SF, but maximum leg spring compression (ΔL) was largest at SF s and decreased by about 25% at ±30%SF s . Significant differences in F max , Δy, k leg and k vert were observed as a function of skill and gender (P < 0.001). Our results indicate that RS is optimised at SF s and that, while k vert follows the changes in SF, k leg is lowest at SF s .

REPRESENTATIONS OF DISTANCE: DIFFERENCES IN UNDERSTANDING DISTANCE ACCORDING TO TRAVEL METHOD

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Gunvor Riber Larsen

2017-12-01

Full Text Available This paper explores how Danish tourists represent distance in relation to their holiday mobility and how these representations of distance are a result of being aero-mobile as opposed to being land-mobile. Based on interviews with Danish tourists, whose holiday mobility ranges from the European continent to global destinations, the first part of this qualitative study identifies three categories of representations of distance that show how distance is being ‘translated’ by the tourists into non-geometric forms: distance as resources, distance as accessibility, and distance as knowledge. The representations of distance articulated by the Danish tourists show that distance is often not viewed in ‘just’ kilometres. Rather, it is understood in forms that express how transcending the physical distance through holiday mobility is dependent on individual social and economic contexts, and on whether the journey was undertaken by air or land. The analysis also shows that being aeromobile is the holiday transportation mode that removes the tourists the furthest away from physical distance, resulting in the distance travelled by air being represented in ways that have the least correlation, in the tourists’ minds, with physical distance measured in kilometres.

Digital Collections Are a Sprint, Not a Marathon: Adapting Scrum Project Management Techniques to Library Digital Initiatives

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Michael Dulock

2015-12-01

Full Text Available This article describes a case study in which a small team from the digital initiatives group and metadata services department at the University of Colorado Boulder (CU-Boulder Libraries conducted a pilot of the Scrum project management framework. The pilot team organized digital initiatives work into short, fixed intervals called sprints—a key component of Scrum. Over a year of working in the modified framework yielded significant improvements to digital collection work, including increased production of digital objects and surrogate records, accelerated publication of digital collections, and an increase in the number of concurrent projects. Adoption of sprints has improved communication and cooperation among participants, reinforced teamwork, and enhanced their ability to adapt to shifting priorities.

Encyclopedia of distances

CERN Document Server

Deza, Michel Marie

2014-01-01

This updated and revised third edition of the leading reference volume on distance metrics includes new items from very active research areas in the use of distances and metrics such as geometry, graph theory, probability theory and analysis. Among the new topics included are, for example, polyhedral metric space, nearness matrix problems, distances between belief assignments, distance-related animal settings, diamond-cutting distances, natural units of length, Heidegger’s de-severance distance, and brain distances. The publication of this volume coincides with intensifying research efforts into metric spaces and especially distance design for applications. Accurate metrics have become a crucial goal in computational biology, image analysis, speech recognition and information retrieval. Leaving aside the practical questions that arise during the selection of a ‘good’ distance function, this work focuses on providing the research community with an invaluable comprehensive listing of the main available di...

Age and gender interactions in short distance triathlon performance.

Science.gov (United States)

Etter, Franziska; Knechtle, Beat; Bukowski, Arkadiusz; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2013-01-01

This study investigated the participation and performance trends as well as the age and gender interaction at the Olympic distance 'Zürich Triathlon' (1.5 km swim, 40 km cycle and 10 km run) from 2000 to 2010 in 7,939 total finishers (1,666 females and 6,273 males). Female triathletes aged from 40 to 54 years significantly (P distance triathlon performance increased after the age of 35 years, which appeared earlier compared to long distance triathlon as suggested by previous studies. Future investigations should compare gender difference in performance for different endurance events across age to confirm a possible effect of exercise duration on gender difference with advancing age.

Interface Simulation Distances

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Pavol Černý

2012-10-01

Full Text Available The classical (boolean notion of refinement for behavioral interfaces of system components is the alternating refinement preorder. In this paper, we define a distance for interfaces, called interface simulation distance. It makes the alternating refinement preorder quantitative by, intuitively, tolerating errors (while counting them in the alternating simulation game. We show that the interface simulation distance satisfies the triangle inequality, that the distance between two interfaces does not increase under parallel composition with a third interface, and that the distance between two interfaces can be bounded from above and below by distances between abstractions of the two interfaces. We illustrate the framework, and the properties of the distances under composition of interfaces, with two case studies.

Validity and reliability of the look Keo power pedal system for measuring power output during incremental and repeated sprint cycling.

Science.gov (United States)

Sparks, S Andy; Dove, Benjamin; Bridge, Craig A; Midgely, Adrian W; McNaughton, Lars R

2015-01-01

Power meters have traditionally been integrated into the crank set, but several manufacturers have designed new systems located elsewhere on the bike, such as inside the pedals. This study aimed to determine the validity and reliability of the Keo power pedals during several laboratory cycling tasks. Ten active male participants (mean ± SD age 34.0 ± 10.6 y, height 1.77 ± 0.04 m, body mass 76.5 ± 10.7 kg) familiar with laboratory cycling protocols completed this study. Each participant was required to complete 2 laboratory cycling trials on an SRM ergometer (SRM, Germany) that was also fitted with the Keo power pedals (Look, France). The trials consisted of an incremental test to exhaustion followed by 10 min rest and then three 10-s sprint tests separated by 3 min of cycling at 100 W. Over power ranges of 75 to 1147 W, the Keo power-pedal system produced typical error values of 0.40, 0.21, and 0.21 for the incremental, sprint, and combined trials, respectively, compared with the SRM. Mean differences of 21.0 and 18.6 W were observed between trials 1 and 2 with the Keo system in the incremental and combined protocols, respectively. In contrast, the SRM produced differences of 1.3 and 0.6 W for the same protocols. The power data from the Keo power pedals should be treated with some caution given the presence of mean differences between them and the SRM. Furthermore, this is exacerbated by poorer reliability than that of the SRM power meter.

Improved Maximum Strength, Vertical Jump and Sprint Performance after 8 Weeks of Jump Squat Training with Individualized Loads

Science.gov (United States)

Marián, Vanderka; Katarína, Longová; Dávid, Olasz; Matúš, Krčmár; Simon, Walker

2016-01-01

The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax) and rate of force development over 100ms (RFD100), countermovement jump (CMJ) and squat jump (SJ) height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg) were divided into experimental (EXP; n = 36) and control (CON, n = 32) groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions). Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, psquats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term. Key points Jump squat exercise is one of many exercises to develop explosive strength that has been the focus of several researches, while the load used during the training seem to be an important factor that affects training outcomes. Experimental group improved performance in all assessed parameters, such as Fmax, RFD100, CMJ, SJ and 50 m sprint time. However, improvements in CMJ and SJ were recorded after the entire power training period and thereafter plateau occurred. The portable FitroDyne could serve as a valuable device to individualize the load that maximizes mean power output and visual feedback can be provided to athletes during the training. PMID:27803628

Analysis of High-Intensity Skating in Top-Class Ice Hockey Match-Play in Relation to Training Status and Muscle Damage.

Science.gov (United States)

Lignell, Erik; Fransson, Dan; Krustrup, Peter; Mohr, Magni

2018-05-01

Lignell, E, Fransson, D, Krustrup, P, and Mohr, M. Analysis of high-intensity skating in top-class ice hockey match-play in relation to training status and muscle damage. J Strength Cond Res 32(5): 1303-1310, 2018-We examined high-intensity activities in a top-class ice-hockey game and the effect of training status. Male ice-hockey players (n = 36) from the National Hockey League participated. Match analysis was performed during a game and physical capacity was assessed by a submaximal Yo-Yo Intermittent Recovery Ice-hockey test, level 1 (YYIR1-IHSUB). Venous blood samples were collected 24-hour post-game to determine markers of muscle damage. Players performed 119 ± 8 and 31 ± 3 m·min of high intensity and sprint skating, respectively, during a game. Total distance covered was 4,606 ± 219 m (2,260-6,749 m), of which high-intensity distance was 2042 ± 97 m (757-3,026 m). Sprint-skating speed was 5-8% higher (p ≤ 0.05) in periods 1 and 2 vs. period 3 and overtime. Defensemen (D) covered 29% more (p ≤ 0.05) skating in total than forwards (F) and were on the ice 47% longer. However, F performed 54% more (p ≤ 0.05) high-intensity skating per minute than defensemen. Plasma creatine kinase (CK) was 338 ± 45 (78-757) U·L 24-hour post-game. Heart rate loading during YYIR1-IHSUB correlated inversely (p ≤ 0.05) to the frequency of high-intensity skating bouts (r = -0.55) and V[Combining Dot Above]O2max (r = -0.85) and positively to post-game CK (r = 0.49; p ≤ 0.05). In conclusion, ice hockey is a multiple-sprint sport that provokes fatigue in the latter half of a game. Forwards perform more intense skating than defensemen. Moreover, high-intensity game activities during top-class ice hockey are correlated with cardiovascular loading during a submaximal skating test. Taken together, training of elite ice-hockey players should improve the ability for repeated high-intensity skating, and testing should include the YYIR1-IHSUB test as an indicator for ice

Determinant Factors of Physical Performance and Specific Throwing in Handball Players of Different Ages.

Science.gov (United States)

Ortega-Becerra, Manuel; Pareja-Blanco, Fernando; Jiménez-Reyes, Pedro; Cuadrado-Peñafiel, Víctor; González-Badillo, Juan J

2018-06-01

Ortega-Becerra, M, Pareja-Blanco, F, Jiménez-Reyes, P, Cuadrado-Peñafiel, V, and González-Badillo, JJ. Determinant factors of physical performance and specific throwing in handball players of different ages. J Strength Cond Res 32(6): 1778-1786, 2018-This study aimed to analyze various fitness qualities in handball players of different ages and to determine the relationships between these parameters and throwing velocity. A total of 44 handball players participated, pooled by age groups: professional (ELITE, n = 13); under-18 (U18, n = 16); under-16 (U16, n = 15). The following tests were completed: 20-m running sprints; countermovement jumps (CMJs); jump squat to determine the load that elicited ∼20 cm jump height (JSLOAD-20 cm); a progressive loading test in full squat and bench press to determine the load that elicited ∼1 m·s (SQ-V1-LOAD and BP-V1-LOAD); and handball throwing (jump throw and 3-step throw). ELITE showed greater performance in almost all sprint distances, CMJ, JSLOAD-20 cm, and bench press strength than U18 and U16. The differences between U18 and U16 were unclear for these variables. ELITE also showed greater (p handball throwing velocity is strongly associated with lower-limb strength, although upper-limb strength, jumping and sprint capacities also play a relevant role in throwing performance, suggesting the need for coaches to include proper strength programs to improve handball players' throwing velocity.

Energy compensation after sprint- and high-intensity interval training.

Science.gov (United States)

Schubert, Matthew M; Palumbo, Elyse; Seay, Rebekah F; Spain, Katie K; Clarke, Holly E

2017-01-01

Many individuals lose less weight than expected in response to exercise interventions when considering the increased energy expenditure of exercise (ExEE). This is due to energy compensation in response to ExEE, which may include increases in energy intake (EI) and decreases in non-exercise physical activity (NEPA). We examined the degree of energy compensation in healthy young men and women in response to interval training. Data were examined from a prior study in which 24 participants (mean age, BMI, & VO2max = 28 yrs, 27.7 kg•m-2, and 32 mL∙kg-1∙min-1) completed either 4 weeks of sprint-interval training or high-intensity interval training. Energy compensation was calculated from changes in body composition (air displacement plethysmography) and exercise energy expenditure was calculated from mean heart rate based on the heart rate-VO2 relationship. Differences between high (≥ 100%) and low (high levels of energy compensation gained fat mass, lost fat-free mass, and had lower change scores for VO2max and NEPA. Linear regression results indicated that lower levels of energy compensation were associated with increases in ΔVO2max (p interval training. In agreement with prior work, increases in ΔVO2max and ΔNEPA were associated with lower energy compensation. Future studies should focus on identifying if a dose-response relationship for energy compensation exists in response to interval training, and what underlying mechanisms and participant traits contribute to the large variation between individuals.

The influence of the playing surface on the exercise intensity of small-sided recreational soccer games

DEFF Research Database (Denmark)

Brito, João; Krustrup, Peter; Rebelo, António

2012-01-01

This study aimed to analyze the influence of the playing surface on movement pattern, physical loading, perceived exertion, and fatigue development during small-sided recreational soccer games. Time-motion, heart rate, blood lactate, and perceived exertion were measured for 16 recreational players...... aged 22 (range: 19-35)yrs. During 5-a-side soccer games on 3 different field surfaces: sand, artificial turf, and asphalt. Jump and sprint tests were performed prior to and after each game. Total distance covered was higher on asphalt and turf than on sand (3.89±0.04 and 3.73±0.12 vs. 2.59±0.21km; p90...

Elite football on artificial turf versus natural grass: Movement patterns, technical standards, and player impressions

DEFF Research Database (Denmark)

Andersson, Helena; Ekblom, Björn; Krustrup, Peter

2008-01-01

The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed...... and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21...

Reducing the distance in distance-caregiving by technology innovation

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Lazelle E Benefield

2007-07-01

Full Text Available Lazelle E Benefield1, Cornelia Beck21College of Nursing, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; 2Pat & Willard Walker Family Memory Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USAAbstract: Family caregivers are responsible for the home care of over 34 million older adults in the United States. For many, the elder family member lives more than an hour’s distance away. Distance caregiving is a growing alternative to more familiar models where: 1 the elder and the family caregiver(s may reside in the same household; or 2 the family caregiver may live nearby but not in the same household as the elder. The distance caregiving model involves elders and their family caregivers who live at some distance, defined as more than a 60-minute commute, from one another. Evidence suggests that distance caregiving is a distinct phenomenon, differs substantially from on-site family caregiving, and requires additional assistance to support the physical, social, and contextual dimensions of the caregiving process. Technology-based assists could virtually connect the caregiver and elder and provide strong support that addresses the elder’s physical, social, cognitive, and/or sensory impairments. Therefore, in today’s era of high technology, it is surprising that so few affordable innovations are being marketed for distance caregiving. This article addresses distance caregiving, proposes the use of technology innovation to support caregiving, and suggests a research agenda to better inform policy decisions related to the unique needs of this situation.Keywords: caregiving, family, distance, technology, elders

The critical distance in laser-induced plasmas: an operative definition

International Nuclear Information System (INIS)

Side, D. Delle; Giuffreda, E.; Nassisi, V.

2016-01-01

We propose a method to estimate a precise value for the critical distance L cr after which three-body recombination stops to produce charge losses in an expanding laser-induced plasma. We show in particular that the total charge collected has a ''reversed sigmoid'' shape as a function of the target-to-detector distance. Fitting the total charge data with a logistic related function, we could consider as L cr the intercept of the tangent to this curve in its inflection point. Furthermore, this value scales well with theoretical predictions. From the application point of view, this could be of great practical interest, since it provide a reliable way to precisely determine the geometry of the extraction system in Laser Ion Sources.

The critical distance in laser-induced plasmas: an operative definition

Science.gov (United States)

Delle Side, D.; Giuffreda, E.; Nassisi, V.

2016-05-01

We propose a method to estimate a precise value for the critical distance Lcr after which three-body recombination stops to produce charge losses in an expanding laser-induced plasma. We show in particular that the total charge collected has a ``reversed sigmoid'' shape as a function of the target-to-detector distance. Fitting the total charge data with a logistic related function, we could consider as Lcr the intercept of the tangent to this curve in its inflection point. Furthermore, this value scales well with theoretical predictions. From the application point of view, this could be of great practical interest, since it provide a reliable way to precisely determine the geometry of the extraction system in Laser Ion Sources.

Censoring distances based on labeled cortical distance maps in cortical morphometry.

Science.gov (United States)

Ceyhan, Elvan; Nishino, Tomoyuki; Alexopolous, Dimitrios; Todd, Richard D; Botteron, Kelly N; Miller, Michael I; Ratnanather, J Tilak

2013-01-01

It has been demonstrated that shape differences in cortical structures may be manifested in neuropsychiatric disorders. Such morphometric differences can be measured by labeled cortical distance mapping (LCDM) which characterizes the morphometry of the laminar cortical mantle of cortical structures. LCDM data consist of signed/labeled distances of gray matter (GM) voxels with respect to GM/white matter (WM) surface. Volumes and other summary measures for each subject and the pooled distances can help determine the morphometric differences between diagnostic groups, however they do not reveal all the morphometric information contained in LCDM distances. To extract more information from LCDM data, censoring of the pooled distances is introduced for each diagnostic group where the range of LCDM distances is partitioned at a fixed increment size; and at each censoring step, the distances not exceeding the censoring distance are kept. Censored LCDM distances inherit the advantages of the pooled distances but also provide information about the location of morphometric differences which cannot be obtained from the pooled distances. However, at each step, the censored distances aggregate, which might confound the results. The influence of data aggregation is investigated with an extensive Monte Carlo simulation analysis and it is demonstrated that this influence is negligible. As an illustrative example, GM of ventral medial prefrontal cortices (VMPFCs) of subjects with major depressive disorder (MDD), subjects at high risk (HR) of MDD, and healthy control (Ctrl) subjects are used. A significant reduction in laminar thickness of the VMPFC in MDD and HR subjects is observed compared to Ctrl subjects. Moreover, the GM LCDM distances (i.e., locations with respect to the GM/WM surface) for which these differences start to occur are determined. The methodology is also applicable to LCDM-based morphometric measures of other cortical structures affected by disease.

Censoring Distances Based on Labeled Cortical Distance Maps in Cortical Morphometry

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Elvan eCeyhan

2013-10-01

Full Text Available It has been demonstrated that shape differences are manifested in cortical structures due to neuropsychiatric disorders. Such morphometric differences can be measured by labeled cortical distance mapping (LCDM which characterizes the morphometry of the laminar cortical mantle of cortical structures. LCDM data consist of signed/labeled distances of gray matter (GM voxels with respect to GM/white matter (WM surface. Volumes and other summary measures for each subject and the pooled distances can help determine the morphometric differences between diagnostic groups, however they do not reveal all the morphometric information con-tained in LCDM distances. To extract more information from LCDM data, censoring of the pooled distances is introduced for each diagnostic group where the range of LCDM distances is partitioned at a fixed increment size; and at each censoring step, the distances not exceeding the censoring distance are kept. Censored LCDM distances inherit the advantages of the pooled distances but also provide information about the location of morphometric differences which cannot be obtained from the pooled distances. However, at each step, the censored distances aggregate, which might confound the results. The influence of data aggregation is investigated with an extensive Monte Carlo simulation analysis and it is demonstrated that this influence is negligible. As an illustrative example, GM of ventral medial prefrontal cortices (VMPFCs of subjects with major depressive disorder (MDD, subjects at high risk (HR of MDD, and healthy control (Ctrl subjects are used. A significant reduction in laminar thickness of the VMPFC in MDD and HR subjects is observed compared to Ctrl subjects. Moreover, the GM LCDM distances (i.e., locations with respect to the GM/WM surface for which these differences start to occur are determined. The methodology is also applicable to LCDM-based morphometric measures of other cortical structures affected by disease.

Training for Distance Teaching through Distance Learning.

Science.gov (United States)

Cadorath, Jill; Harris, Simon; Encinas, Fatima

2002-01-01

Describes a mixed-mode bachelor degree course in English language teaching at the Universidad Autonoma de Puebla (Mexico) that was designed to help practicing teachers write appropriate distance education materials by giving them the experience of being distance students. Includes a course outline and results of a course evaluation. (Author/LRW)

Physical Demands of Top-Class Soccer Friendly Matches in Relation to a Playing Position Using Global Positioning System Technology

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Mallo Javier

2015-09-01

Full Text Available The aim of this study was to examine the physical demands imposed on professional soccer players during 11-a-side friendly matches in relation to their playing position, using global positioning system (GPS technology. One hundred and eleven match performances of a Spanish “La Liga” team during the 2010-11 and 2011-12 pre-seasons were selected for analysis. The activities of the players were monitored using GPS technology with a sampling frequency of 1 Hz. Total distance covered, distance in different speed categories, accelerations, and heart rate responses were analyzed in relation to five different playing positions: central defenders (n=23, full-backs (n=20, central midfielders (n=22, wide midfielders (n=26, and forwards (n=20. Distance covered during a match averaged 10.8 km, with wide and central midfielders covering the greatest total distance. Specifically, wide midfielders covered the greatest distances by very high-intensity running (>19.8 km·h-1 and central midfielders by jogging and running (7.2-19.7 km·h-1. On the other hand, central defenders covered the least total distance and at high intensity, although carried out more (p<0.05-0.01 accelerations than forwards, wide midfielders, and fullbacks. The work rate profile of the players obtained with the GPS was very similar to that obtained with semi-automatic image technologies. However, when comparing results from this study with data available in the literature, important differences were detected in the amount of distance covered by sprinting, which suggests that caution should be taken when comparing data obtained with the GPS with other motion analysis systems, especially regarding high-intensity activities.

Benefit and harm of intensive blood pressure treatment: Derivation and validation of risk models using data from the SPRINT and ACCORD trials.

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Sanjay Basu

2017-10-01

Full Text Available Intensive blood pressure (BP treatment can avert cardiovascular disease (CVD events but can cause some serious adverse events. We sought to develop and validate risk models for predicting absolute risk difference (increased risk or decreased risk for CVD events and serious adverse events from intensive BP therapy. A secondary aim was to test if the statistical method of elastic net regularization would improve the estimation of risk models for predicting absolute risk difference, as compared to a traditional backwards variable selection approach.Cox models were derived from SPRINT trial data and validated on ACCORD-BP trial data to estimate risk of CVD events and serious adverse events; the models included terms for intensive BP treatment and heterogeneous response to intensive treatment. The Cox models were then used to estimate the absolute reduction in probability of CVD events (benefit and absolute increase in probability of serious adverse events (harm for each individual from intensive treatment. We compared the method of elastic net regularization, which uses repeated internal cross-validation to select variables and estimate coefficients in the presence of collinearity, to a traditional backwards variable selection approach. Data from 9,069 SPRINT participants with complete data on covariates were utilized for model development, and data from 4,498 ACCORD-BP participants with complete data were utilized for model validation. Participants were exposed to intensive (goal systolic pressure < 120 mm Hg versus standard (<140 mm Hg treatment. Two composite primary outcome measures were evaluated: (i CVD events/deaths (myocardial infarction, acute coronary syndrome, stroke, congestive heart failure, or CVD death, and (ii serious adverse events (hypotension, syncope, electrolyte abnormalities, bradycardia, or acute kidney injury/failure. The model for CVD chosen through elastic net regularization included interaction terms suggesting that older

The Sprint/1 language for the dynamic evaluation of the mathematic formulas by direct communication with a computer; Le langage Sprint/1 pour l'evaluation dynamique des formules mathematiques par dialogue direct avec un ordinateur

Energy Technology Data Exchange (ETDEWEB)

Cavadia, I C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, direction des piles atomiques, direction du CEN-Saclay

1968-06-01

The Sprint/1 system is indented for real-time production of present day computers and can be used by persons without a special preparation in the programming field. All input operations (instructions, comments, data) and corresponding output operations (printing of results and diagnostics) are done by a type-writer. It assures a bidirectional communication between the user and his program during its execution, the user indicating to the computer each step that must be performed to resolve the problem. At the same time the machine immediately flags the detection of a syntax or semantic error which allows him to correct or to improve his program immediately. It should be emphasized that the language is an evolutive one. Each introduced instruction enriches the language, the user having the possibility to easily build complex structures from very simple expressions. Thus he can make a general study of the behaviour of a dynamic learning process of the machine which constitutes one of the characteristics of artificial intelligence. (author) [French] Le systeme SPRINT/1 est destine a l'exploitation en temps reel des ordinateurs actuels et peut etre utilise par des personnes sans une preparation speciale dans le domaine de la programmation. Toutes les operations d'entree (d'instructions, de commentaires et de donnees) et respectivement de sortie (impression des resultats et de diagnostics) sont realisees a l'aide d'une machine a ecrire. Elle assure une communication bidirectionnelle entre l'utilisateur et son programme pendant l'execution de celui-ci, l'utilisateur indiquant a l'ordinateur chaque etape qu'il doit entreprendre afin de resoudre le probleme. En meme temps la machine signale immediatement l'apparition d'une erreur de syntaxe ou de semantique ce qui permet de corriger ou d'ameliorer sur place le programme. Il faut souligner le fait que le langage est evolutif. Chaque instruction introduite enrichit le lexique, l'utilisateur ayant la possibilite de construire

Tourists consuming distance

DEFF Research Database (Denmark)

Larsen, Gunvor Riber

The environmental impact of tourism mobility is linked to the distances travelled in order to reach a holiday destination, and with tourists travelling more and further than previously, an understanding of how the tourists view the distance they travel across becomes relevant. Based on interviews...... contribute to an understanding of how it is possible to change tourism travel behaviour towards becoming more sustainable. How tourists 'consume distance' is discussed, from the practical level of actually driving the car or sitting in the air plane, to the symbolic consumption of distance that occurs when...... travelling on holiday becomes part of a lifestyle and a social positioning game. Further, different types of tourist distance consumers are identified, ranging from the reluctant to the deliberate and nonchalant distance consumers, who display very differing attitudes towards the distance they all travel...

Physical activity profile of 2014 FIFA World Cup players, with regard to different ranges of air temperature and relative humidity

Science.gov (United States)

Chmura, Paweł; Konefał, Marek; Andrzejewski, Marcin; Kosowski, Jakub; Rokita, Andrzej; Chmura, Jan

2017-04-01

The present study attempts to assess changes in soccer players' physical activity profiles under the simultaneous influence of the different combinations of ambient temperature and relative humidity characterising matches of the 2014 FIFA World Cup hosted by Brazil. The study material consisted of observations of 340 players representing 32 national teams taking part in the tournament. The measured indices included total distances covered; distances covered with low, moderate, or high intensity; numbers of sprints performed, and peak running speeds achieved. The analysis was carried out using FIFA official match data from the Castrol Performance Index system. Ultimately, consideration was given to a combination of three air temperature ranges, i.e. below 22 °C, 22-28 °C, and above 28 °C; and two relative humidity ranges below 60 % and above 60 %. The greatest average distance recorded (10.54 ± 0.91 km) covered by players at an air temperature below 22 °C and a relative humidity below 60 %, while the shortest (9.83 ± 1.08 km) characterised the same air temperature range, but conditions of relative humidity above 60 % ( p ≤ 0.001). Two-way ANOVA revealed significant differences ( p ≤ 0.001) in numbers of sprints performed by players, depending on whether the air temperature range was below 22 °C (40.48 ± 11.17) or above 28 °C (30.72 ± 9.40), but only where the relative humidity was at the same time below 60 %. Results presented indicate that the conditions most comfortable for physical activity on the part of players occur at 22 °C, and with relative humidity under 60 %.

Analytic processing of distance.

Science.gov (United States)

Dopkins, Stephen; Galyer, Darin

2018-01-01

How does a human observer extract from the distance between two frontal points the component corresponding to an axis of a rectangular reference frame? To find out we had participants classify pairs of small circles, varying on the horizontal and vertical axes of a computer screen, in terms of the horizontal distance between them. A response signal controlled response time. The error rate depended on the irrelevant vertical as well as the relevant horizontal distance between the test circles with the relevant distance effect being larger than the irrelevant distance effect. The results implied that the horizontal distance between the test circles was imperfectly extracted from the overall distance between them. The results supported an account, derived from the Exemplar Based Random Walk model (Nosofsky & Palmieri, 1997), under which distance classification is based on the overall distance between the test circles, with relevant distance being extracted from overall distance to the extent that the relevant and irrelevant axes are differentially weighted so as to reduce the contribution of irrelevant distance to overall distance. The results did not support an account, derived from the General Recognition Theory (Ashby & Maddox, 1994), under which distance classification is based on the relevant distance between the test circles, with the irrelevant distance effect arising because a test circle's perceived location on the relevant axis depends on its location on the irrelevant axis, and with relevant distance being extracted from overall distance to the extent that this dependency is absent. Copyright © 2017 Elsevier B.V. All rights reserved.

Tactical behaviour of winning athletes in major championship 1500-m and 5000-m track finals.

Science.gov (United States)

Aragón, Sonia; Lapresa, Daniel; Arana, Javier; Anguera, M Teresa; Garzón, Belén

2016-01-01

This article analyses the tactics employed by middle-distance (1500-m) and long-distance (5000-m) runners from an observational methodology perspective. The subject of investigation has received little attention from specialists in the field of athletics, with most research focusing on physiological studies of athlete performance. Using an ad hoc observation tool and a database containing systematically recorded data we detected time patterns (T-patterns) within the data recorded using the Theme software program (version 5.0), and analysed the tactics employed by winners of the men's 1500-m and 5000-m finals of the World Championships in Athletics [Edmonton 2001, Paris 2003, Helsinki 2005 (1500-m final only), Osaka 2007 (1500-m final only), Berlin 2009 and Daegu 2011], the European Athletics Championships (Munich 2002, Göteborg 2006, and Barcelona 2010) and the Olympic Games (Sydney 2000, Athens 2004, Beijing 2008 and London 2012). T-pattern detection and investigation of the relationship between category systems corresponding to the criteria comprising the observation tool revealed both similarities (starting lane and lane used during race, runner's position during race and sprint zone and lane) and differences (variations in pace, zones in which changes of pace occur, sprint initiation zone and winner's position at the start of the sprint) between the two disciplines.

Distancing, not embracing, the Distancing-Embracing model of art reception.

Science.gov (United States)

Davies, Stephen

2017-01-01

Despite denials in the target article, the Distancing-Embracing model appeals to compensatory ideas in explaining the appeal of artworks that elicit negative affect. The model also appeals to the deflationary effects of psychological distancing. Having pointed to the famous rejection in the 1960s of the view that aesthetic experience involves psychological distancing, I suggest that "distance" functions here as a weak metaphor that cannot sustain the explanatory burden the theory demands of it.

Distance-Based Functional Diversity Measures and Their Decomposition: A Framework Based on Hill Numbers

Science.gov (United States)

Chiu, Chun-Huo; Chao, Anne

2014-01-01

Hill numbers (or the “effective number of species”) are increasingly used to characterize species diversity of an assemblage. This work extends Hill numbers to incorporate species pairwise functional distances calculated from species traits. We derive a parametric class of functional Hill numbers, which quantify “the effective number of equally abundant and (functionally) equally distinct species” in an assemblage. We also propose a class of mean functional diversity (per species), which quantifies the effective sum of functional distances between a fixed species to all other species. The product of the functional Hill number and the mean functional diversity thus quantifies the (total) functional diversity, i.e., the effective total distance between species of the assemblage. The three measures (functional Hill numbers, mean functional diversity and total functional diversity) quantify different aspects of species trait space, and all are based on species abundance and species pairwise functional distances. When all species are equally distinct, our functional Hill numbers reduce to ordinary Hill numbers. When species abundances are not considered or species are equally abundant, our total functional diversity reduces to the sum of all pairwise distances between species of an assemblage. The functional Hill numbers and the mean functional diversity both satisfy a replication principle, implying the total functional diversity satisfies a quadratic replication principle. When there are multiple assemblages defined by the investigator, each of the three measures of the pooled assemblage (gamma) can be multiplicatively decomposed into alpha and beta components, and the two components are independent. The resulting beta component measures pure functional differentiation among assemblages and can be further transformed to obtain several classes of normalized functional similarity (or differentiation) measures, including N-assemblage functional generalizations of

Distance-based functional diversity measures and their decomposition: a framework based on Hill numbers.

Directory of Open Access Journals (Sweden)

Chun-Huo Chiu

Full Text Available Hill numbers (or the "effective number of species" are increasingly used to characterize species diversity of an assemblage. This work extends Hill numbers to incorporate species pairwise functional distances calculated from species traits. We derive a parametric class of functional Hill numbers, which quantify "the effective number of equally abundant and (functionally equally distinct species" in an assemblage. We also propose a class of mean functional diversity (per species, which quantifies the effective sum of functional distances between a fixed species to all other species. The product of the functional Hill number and the mean functional diversity thus quantifies the (total functional diversity, i.e., the effective total distance between species of the assemblage. The three measures (functional Hill numbers, mean functional diversity and total functional diversity quantify different aspects of species trait space, and all are based on species abundance and species pairwise functional distances. When all species are equally distinct, our functional Hill numbers reduce to ordinary Hill numbers. When species abundances are not considered or species are equally abundant, our total functional diversity reduces to the sum of all pairwise distances between species of an assemblage. The functional Hill numbers and the mean functional diversity both satisfy a replication principle, implying the total functional diversity satisfies a quadratic replication principle. When there are multiple assemblages defined by the investigator, each of the three measures of the pooled assemblage (gamma can be multiplicatively decomposed into alpha and beta components, and the two components are independent. The resulting beta component measures pure functional differentiation among assemblages and can be further transformed to obtain several classes of normalized functional similarity (or differentiation measures, including N-assemblage functional

Foundations of Distance Education. Third Edition. Routledge Studies in Distance Education.

Science.gov (United States)

Keegan, Desmond

This text gives an overview of distance education for students, administrators, and practitioners in distance education. Chapter 1 discusses the study of distance education. Chapter 2 analyzes forms of nonconventional education (open, nontraditional) that may have similarities to distance education but are not to be identified with it. Chapter 3…

modelling distances

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Robert F. Love

2001-01-01

Full Text Available Distance predicting functions may be used in a variety of applications for estimating travel distances between points. To evaluate the accuracy of a distance predicting function and to determine its parameters, a goodness-of-fit criteria is employed. AD (Absolute Deviations, SD (Squared Deviations and NAD (Normalized Absolute Deviations are the three criteria that are mostly employed in practice. In the literature some assumptions have been made about the properties of each criterion. In this paper, we present statistical analyses performed to compare the three criteria from different perspectives. For this purpose, we employ the ℓkpθ-norm as the distance predicting function, and statistically compare the three criteria by using normalized absolute prediction error distributions in seventeen geographical regions. We find that there exist no significant differences between the criteria. However, since the criterion SD has desirable properties in terms of distance modelling procedures, we suggest its use in practice.

Effect of tapering after a period of high-volume sprint interval training on running performance and muscular adaptations in moderately trained runners

DEFF Research Database (Denmark)

Skovgaard, Casper; Almquist, Nicki Winfield; Kvorning, Thue

2018-01-01

The effect of tapering following a period of high-volume sprint interval training (SIT) and a basic volume of aerobic training on performance and muscle adaptations in moderately trained runners was examined. Eleven (8 males, 3 females) runners (maximum oxygen uptake (VO2-max): 56.8±2.9 mL·min(-1...... running test at 90% of vVO2-max to exhaustion (RRT). In addition, a biopsy from m. vastus lateralis was obtained at rest. Performance during RRT was better (P... at 60% of vVO2-max was lower (P

Predictors of high-intensity running capacity in collegiate women during a soccer game.

Science.gov (United States)

McCormack, William P; Stout, Jeffrey R; Wells, Adam J; Gonzalez, Adam M; Mangine, Gerald T; Fragala, Maren S; Hoffman, Jay R

2014-04-01

The purpose of this investigation was to determine which physiological assessments best predicted high-intensity running (HIR) performance during a women's collegiate soccer game. A secondary purpose was to examine the relationships among physiological performance measures including muscle architecture on soccer performance (distance covered, HIR, and sprints during the game) during a competitive collegiate women's soccer game. Ten National Collegiate Athletic Association (NCAA) Division I women soccer players performed physiological assessments within a 2-week period before a competitive regulation soccer game performed during the spring season. Testing consisted of height, body mass, ultrasound measurement of dominant (DOMleg), and nondominant leg (NDOMleg) vastus lateralis for muscle thickness (MT) and pennation angle (PA), VO2max, running economy, and Wingate anaerobic test (WAnT) for peak power (PP), mean power (MP), and fatigue rate (FR). During the game, distance run, HIR, and sprints were measured using a 10-Hz global positioning system. Stepwise regression revealed that VO2max, dominant leg thickness, and dominant leg PA were the strongest predictors of HIR distance during the game (R = 0.989, SEE = 115.5 m, p = 0.001). V[Combining Dot Above]O2max was significantly correlated with total distance run (r = 0.831; p = 0.003), HIR (r = 0.755; p = 0.012), WAnTPP (r = -0.737; p = 0.015), WAnTPP·kg (r = -0.706; p = 0.022), and WAnTFR (r = -0.713; p = 0.021). DOMlegMT was significantly correlated with WAnTFR (r = 0.893; p = 0.001). DOMlegPA was significantly correlated with WAnTFR (r = 0.740; p = 0.023). The NDOMlegPA was significantly correlated to peak running velocity (r = 0.781; p = 0.013) and WAnT MP·kg (r = 0.801; p = 0.01). Results of this study indicate that V[Combining Dot Above]O2max and muscle architecture are important characteristics of NCAA Division I women soccer players and may predict HIR distance during a competitive contest.

EFFECTS OF DISTANCE SPECIALIZATION ON THE BACKSTROKE SWIMMING KINEMATICS

Directory of Open Access Journals (Sweden)

Cortesi Matteo