Chronic low-frequency rTMS of primary motor cortex diminishes exercise training-induced gains in maximal voluntary force in humans.

Although there is consensus that the central nervous system mediates the increases in maximal voluntary force (maximal voluntary contraction, MVC) produced by resistance exercise, the involvement of the primary motor cortex (M1) in these processes remains controversial. We hypothesized that 1-Hz repetitive transcranial magnetic stimulation (rTMS) of M1 during resistance training would diminish strength gains. Forty subjects were divided equally into five groups. Subjects voluntarily (Vol) abducted the first dorsal interosseus (FDI) (5 bouts x 10 repetitions, 10 sessions, 4 wk) at 70-80% MVC. Another group also exercised but in the 1-min-long interbout rest intervals they received rTMS [Vol+rTMS, 1 Hz, FDI motor area, 300 pulses/session, 120% of the resting motor threshold (rMT)]. The third group also exercised and received sham rTMS (Vol+Sham). The fourth group received only rTMS (rTMS_only). The 37.5% and 33.3% gains in MVC in Vol and Vol+Sham groups, respectively, were greater (P = 0.001) than the 18.9% gain in Vol+rTMS, 1.9% in rTMS_only, and 2.6% in unexercised control subjects who received no stimulation. Acutely, within sessions 5 and 10, single-pulse TMS revealed that motor-evoked potential size and recruitment curve slopes were reduced in Vol+rTMS and rTMS_only groups and accumulated to chronic reductions by session 10. There were no changes in rMT, maximum compound action potential amplitude (M(max)), and peripherally evoked twitch forces in the trained FDI and the untrained abductor digiti minimi. Although contributions from spinal sources cannot be excluded, the data suggest that M1 may play a role in mediating neural adaptations to strength training.

Effect of a general school-based physical activity intervention on bone mineral content and density: A cluster-randomized controlled trial.

Background: Specific physical loading leads to enhanced bone development during childhood. A general physical activity program mimicking a real-life situation was successful at increasing general physical health in children. Yet, it is not clear whether it can equally increase bone mineral mass. We performed a cluster-randomized controlled trial in children of both gender and different pubertal stages to determine whether a school-based physical activity (PA) program during one school-year influences bone mineral content (BMC) and density (BMD), irrespective of gender.Methods: Twenty-eight 1st and 5th grade (6-7 and 11-12 year-old) classes were cluster randomized to an intervention (INT, 16 classes, n = 297) and control (CON; 12 classes, n = 205) group. The intervention consisted of a multi-component PA intervention including daily physical education with at least 10 min of jumping or strength training exercises of various intensities. Measurements included anthropometry, and BMC and BMD of total body, femoral neck, total hip and lumbar spine using dual-energy X-ray absorptiometry (DXA). PA was assessed by accelerometers and Tanner stages by questionnaires. Analyses were performed by a regression model adjusted for gender, baseline height and weight, baseline PA, post-intervention pubertal stage, baseline BMC, and cluster.Results: 275 (72%) of 380 children who initially agreed to have DXA measurements had also post-intervention DXA and PA data. Mean age of prepubertal and pubertal children at baseline was 8.7 +/- 2.1 and 11.1 +/- 0.6 years, respectively. Compared to CON, children in INT showed statistically significant increases in BMC of total body, femoral neck, and lumbar spine by 5.5%, 5.4% and 4.7% (all p < 0.05), respectively, and BMD of total body and lumbar spine by 8.4% and 7.3% (both p < 0.01), respectively. There was no gender*group, but a pubertal stage*group interaction consistently favoring prepubertal children.Conclusion: A general school-based PA intervention can increase bone health in elementary school children of both genders, particularly before puberty. (C) 2010 Elsevier Inc. All rights reserved.

Le réentraînement à l'effort chez l'enfant atteint de paralysie cérébrale (PC)

Le réentraînement à l'effort est présenté aujourd'hui comme un moyen efficace de lutter et réduire des déficiences chroniques chez l'adulte atteint de pathologie chronique. Il a été proposé plus récemment chez le jeune (enfant ou adolescent) atteint de pathologies neurologiques, notamment la paralysie cérébrale. De nombreuses études à ce jour présentent des résultats encourageants dans l'amélioration de certains facteurs de qualité de vie chez des jeunes patients atteints de paralysie cérébrale. Tout d'abord, un entraînement à l'effort sur la base d'exercices réalisés en endurance permet d'améliorer les capacités aérobies ainsi que le périmètre et la vitesse de marche et la motricité globale. Un entraînement à base de renforcement musculaire favoriserait aussi l'augmentation de la masse musculaire et induirait une amélioration de la motricité globale. Enfin, il semble que le type d'exercice à privilégier actuellement soit un entraînement « mixte », à base d'exercices associant les deux modes d'entraînement précédents. Pour préciser les modalités pratiques de réalisation de ces entraînements, il faudra tenir compte de différents paramètres parmi lesquels la fatigue musculaire.

Success of a general school-based physical activity intervention on bone mineral content depends on pubertal stage but not on gender

Aims: We performed a randomised controlled trial in children of both gender and different pubertal stages to determine whether a school-based physical activity (PA) program during a full schoolyear influences bone mineral content (BMC) and whether there are differences in response for boys and girls before and during puberty. Methods: Twenty-eight 1st and 5th grade classes were cluster randomised to an intervention (INT, 16 classes, n=297) and control (CON; 12 classes, n=205) group. The intervention consisted of a multi-component PA intervention including daily physical education during a full school year. Each lesson was predetermined, included about ten minutes of jumping or strength training exercises of various intensity and was the same for all children. Measurements included anthropometry (height and weight), tanner stages (by self-assessment), PA (by accelerometry) and BMC for total body, femoral neck, total hip and lumbar spine using dualenergy X-ray absorptiometry (DXA). Bone parameters were normalized for gender and tanner stage (pre- vs. puberty). Analyses were performed by a regression model adjusted for gender, baseline height, baseline weight, baseline PA, post-intervention tanner stage, baseline BMC, and cluster. Researchers were blinded to group allocation. Children in the control group did not know about the intervention arm. Results: 217 (57%) of 380 children who initially agreed to have DXA measurements had also post-intervention DXA and PA data. Mean age of prepubertal and pubertal children at baseline was 9.0±2.1 and 11.2±0.6 years, respectively. 47/114 girls and 68/103 boys were prepubertal at the end of the intervention. Compared to CON, children in INT showed statistically significant increases in BMC of total body (adjusted z-score differences: 0.123; 95%>CI 0.035 to 0.212), femoral neck (0.155; 95%>CI 0.007 to 0.302), and lumbar spine (0.127; 95%>CI 0.026 to 0.228). Importantly, there was no gender*group, but a tanner*group interaction consistently favoring prepubertal children. Conclusions: Our findings show that a general, but stringent school-based PA intervention can improve BMC in elementary school children. Pubertal stage, but not gender seems to determine bone sensitivity to physical activity loading.

Conceptual framework for strengthening exercises to prevent hamstring strains

High-speed running accounts for the majority of hamstring strains in many sports. The terminal swing phase is believed to be the most hazardous as the hamstrings are undergoing an active lengthening contraction in a long muscle length position. Prevention-based strength training mainly focuses on eccentric exercises. However, it appears crucial to integrate other parameters than the contraction type. Therefore, the aim of this study is to present a conceptual framework based on six key parameters (contraction type, load, range of motion, angular velocity, uni-/bilateral exercises, kinetic chain) for the hamstring's strength exercise for strain prevention. Based on the biomechanical parameters of sprinting, it is proposed to use high-load eccentric contractions. The movement should be performed at a slow to moderate angular velocity and focused at the knee joint, while the hip is kept in a large flexion position in order to reach a greater elongation stress of the hamstrings than in the terminal swing phase. In this way, we believe that, during sprinting, athletes would be better trained to brake the knee extension effectively in the whole range of motion without overstretch of the hamstrings. Finally, based on its functional application, unilateral open kinetic chain should be preferred.

Evaluation et prise en charge des risques de blessure des ischio-jambiers chez le sprinteur

La déchirure des ischio-jambiers est la blessure non-traumatique la plus fréquemment rencontrée dans les sports demandant une course à haute vitesse. Les ischio-jambiers sont particulièrement vulnérables lors de la fin de phase d'oscillation du sprint étant donné qu'ils se contractent excentriquement alors qu'ils sont en position d'allongement. Le renforcement excentrique a été montré comme étant une méthode efficace pour diminuer le risque de blessure. Cependant, les exercices classiquement utilisés comme le Nordic hamstring ne soumettent pas les ischio-jambiers à un niveau d'allongement spécifique au sprint. Dès lors, l'objectif de cette thèse était d'évaluer le fonctionnement des ischio-jambiers à différents niveaux d'allongement musculo- tendineux puis de transposer dans la pratique les résultats obtenus afin de concevoir des exercices plus spécifiques aux besoins des athlètes. Avant cela, une première partie avait pour but de proposer de nouvelles méthodes d'évaluation de terrain des ischio-jambiers. Les différents travaux réalisés pour cette thèse ont permis : 1) de proposer deux nouveaux outils de terrain pour l'évaluation de la flexibilité et de la force des ischio-jambiers ; 2) de montrer que le niveau d'allongement influence directement la force produite par les ischio-jambiers et de suggérer que ce niveau d'allongement semble être un stimulus au moins aussi déterminant que le mode de contraction musculaire pour générer des adaptations de l'architecture musculaire propices à la diminution du risque de blessure ; 3) de proposer des modalités spécifiques de renforcement des ischio-jambiers destinées aux sprinteurs dans une perspective de prévention des blessures et de montrer l'efficacité de ces recommandations sur l'amélioration d'un certain nombre de facteurs de risque de blessure. Finalement, ce travail a ouvert de nouvelles perspectives allant de la proposition d'exercices de renforcement de terrain au développement d'un système motorisé spécifique au sprint permettant le renforcement et l'évaluation de la force des ischio-jambiers en passant par différents projets de recherche. -- High-speed running sports accounts for the majority of hamstring strains. The terminal swing phase of the running cycle is believed to be the most hazardous as the hamstrings are undergoing an active lengthening contraction in a long muscle length position. Prevention-based strength training relies mainly on eccentric exercises. However, most hamstrings exercises like the Nordic hamstring are performed at an inadequately low hip-flexion angle. Thus, the objective of this thesis was to assess the hamstring function at different muscle lengths and depending on the obtained results to design strength exercises more specific to the athlete's need. Before that, a first part of this thesis aimed to develop new assessment methods of the hamstring on site. The different studies included in the present thesis allowed: 1) to propose two new methods to test the hamstring flexibility and strength on the field; 2) to show that the hamstring muscle length directly influences its level of strength, and to suggest that the training range of motion could be a dominant stimulus (as important than contraction type) for modifying the muscle architecture, which leads to a decrease in hamstring injury risk; 3) to define sprint specific parameters for prevention-based strength training, and to show the efficiency of these recommendations on the improvement of several injury risk factors for the hamstring. Finally, this thesis proposed new perspectives: 1) new strength exercises on site; 2) the development of a motorised device specific for the sprint which could be used to strength and to assess the hamstring; 3) several future research projects.

Vibration training elicits a mixed aerobic and resistance-type exercise in sedentary subjects.

Objective. Vibration training (VT) is a new exercise method, with good acceptance among sedentary subjects, due to its passive principle: the machine moves the subject, not the opposite. We hypothesize that untrained subjects can benefit from a greater cardiovascular and metabolic stimulation than trained athletes, resembling classical aerobic-type activity, in addition of eliciting strength gains shown in diverse studies. Methods. 3 group of male subjects, inactive (SED), endurance trained athletes (END) and strength trained athletes (STR) underwent fitness (VO2max) and lower-body strength tests (isokinetic). Subjects were submitted to a session of oscillating VT, composed of 3 exercises (isometric half-squat, dynamic squat, dynamic squat with added load), each of 3 minutes duration, and repeated at 3 frequencies. VO2, heart rate and Borg scale were monitored. Results. 27 healthy subjects (10 SED, 9 END and 8 STR), mean age 24.5 (SED), 25.0 (STR) and 29.8 (END) were included. VO2max was significantly different as expected (47.9 vs. 52.9 vs. 63.9 ml/kg/min, resp. for SED, STR and END). Isokinetic dominant leg extensors strength was higher in STR (3.32 Nm/kg vs. 2.60 and 2.74 in SED and END). During VT, peak oxygen consumption (% of VO2max) attained was 59.3 in SED, 50.8 in STR and 48.0 in END (P<0.001 between SED and other subjects). Peak heart rate (% of heart rate max) was 82.7 in SED, 80.4 in STR and 72.4 in END. In SED, dynamic exercises without extra load elicited 51.0% of VO2max and 72.1% of heart rate max, and perceived effort reached 15.1/20. Conclusions. VT is an unconventional type of exercise, which has been shown to enhance strength, bone density, balance and flexibility. Users are attracted by the relative passivity. In SED, we show that VT elicits sufficient cardiovascular response to benefit overall fitness in addition to the known strength effects. VT's higher acceptance as an exercise in sedentary people, compared to jogging or cycling for example, can lead to better adherence to physical activity. Although long-term effects of VT on health are not avalaible, we believe this type of combination of aerobic and resistance-type exercise can be beneficial on multiple health parameters, especially cardiovascular health.

Position statement--altitude training for improving team-sport players' performance: current knowledge and unresolved issues.

Despite the limited research on the effects of altitude (or hypoxic) training interventions on team-sport performance, players from all around the world engaged in these sports are now using altitude training more than ever before. In March 2013, an Altitude Training and Team Sports conference was held in Doha, Qatar, to establish a forum of research and practical insights into this rapidly growing field. A round-table meeting in which the panellists engaged in focused discussions concluded this conference. This has resulted in the present position statement, designed to highlight some key issues raised during the debates and to integrate the ideas into a shared conceptual framework. The present signposting document has been developed for use by support teams (coaches, performance scientists, physicians, strength and conditioning staff) and other professionals who have an interest in the practical application of altitude training for team sports. After more than four decades of research, there is still no consensus on the optimal strategies to elicit the best results from altitude training in a team-sport population. However, there are some recommended strategies discussed in this position statement to adopt for improving the acclimatisation process when training/competing at altitude and for potentially enhancing sea-level performance. It is our hope that this information will be intriguing, balanced and, more importantly, stimulating to the point that it promotes constructive discussion and serves as a guide for future research aimed at advancing the bourgeoning body of knowledge in the area of altitude training for team sports.

High-intensity intermittent training in hypoxia: a double-blinded, placebo-controlled field study in youth football players.

High-intensity intermittent training in hypoxia: A double-blinded, placebo-controlled field study in youth football players. J Strength Cond Res 29(1): 226-237, 2015-This study examined the effects of 5 weeks (∼60 minutes per training, 2 d·wk) of run-based high-intensity repeated-sprint ability (RSA) and explosive strength/agility/sprint training in either normobaric hypoxia repeated sprints in hypoxia (RSH; inspired oxygen fraction [FIO2] = 14.3%) or repeated sprints in normoxia (RSN; FIO2 = 21.0%) on physical performance in 16 highly trained, under-18 male footballers. For both RSH (n = 8) and RSN (n = 8) groups, lower-limb explosive power, sprinting (10-40 m) times, maximal aerobic speed, repeated-sprint (10 × 30 m, 30-s rest) and repeated-agility (RA) (6 × 20 m, 30-s rest) abilities were evaluated in normoxia before and after supervised training. Lower-limb explosive power (+6.5 ± 1.9% vs. +5.0 ± 7.6% for RSH and RSN, respectively; both p < 0.001) and performance during maximal sprinting increased (from -6.6 ± 2.2% vs. -4.3 ± 2.6% at 10 m to -1.7 ± 1.7% vs. -1.3 ± 2.3% at 40 m for RSH and RSN, respectively; p values ranging from <0.05 to <0.01) to a similar extent in RSH and RSN. Both groups improved best (-3.0 ± 1.7% vs. -2.3 ± 1.8%; both p ≤ 0.05) and mean (-3.2 ± 1.7%, p < 0.01 vs. -1.9 ± 2.6%, p ≤ 0.05 for RSH and RSN, respectively) repeated-sprint times, whereas sprint decrement did not change. Significant interactions effects (p ≤ 0.05) between condition and time were found for RA ability-related parameters with very likely greater gains (p ≤ 0.05) for RSH than RSN (initial sprint: 4.4 ± 1.9% vs. 2.0 ± 1.7% and cumulated times: 4.3 ± 0.6% vs. 2.4 ± 1.7%). Maximal aerobic speed remained unchanged throughout the protocol. In youth highly trained football players, the addition of 10 repeated-sprint training sessions performed in hypoxia vs. normoxia to their regular football practice over a 5-week in-season period was more efficient at enhancing RA ability (including direction changes), whereas it had no additional effect on improvements in lower-limb explosive power, maximal sprinting, and RSA performance.

Cardiovascular and metabolic responses during isokinetic shoulder rotators strength testing in healthy subjects

Background: Although there have been many studies on isokinetic shoulder exercises in evaluation and rehabilitation programs, the cardiovascular and metabolic responses of those modes of muscle strength exercises have been poorly investigated. Objective: To analyze cardiovascular and metabolic responses during a standardized test used to study the internal (IR) and external (ER) rotators maximal isokinetic strength. Methods: Four days after an incremental exercise test on cycle ergometer, ten healthy subjects performed an isokinetic shoulder strength evaluation with cardiovascular (Heart rate, HR) and metabolic gas exchange (&Vdot;O_{2}) analysis. The IR and ER isokinetic strength, measured in seated position with 45° of shoulder abduction in scapular plane, was evaluated concentrically at 60, 120 and 240°/s and eccentrically at 60°/s, for both shoulder sides. An endurance test with 30 repetitions at 240°/s was performed at the end of each shoulder side testing. Results: There was a significant increase of mean HR with isokinetic exercise (P< 0.05). Increases of HR was 42-71% over the resting values. During endurance testing, increases of HR was 77-105% over the resting values, and corresponded to 85-86% of the maximal HR during incremental test. Increase of &Vdot;O_{2} during isokinetic exercises was from 6-11 ml/min/kg to 20-43 ml/min/kg. Conclusion: This study performed significant cardiovascular and metabolic responses to isokinetic exercise of rotators shoulder muscles. A warm-up should be performed before maximal high-intensity isokinetic shoulder testing. Our results indicated that observation and supervision are important during testing and/or training sessions, especially in subjects with risk for cardiovascular disorders.

Triathlon event distance specialization: training and injury effects.

We conducted a preliminary, questionnaire-based, retrospective analysis of training and injury in British National Squad Olympic distance (OD) and Ironman distance (IR) triathletes. The main outcome measures were training duration and training frequency and injury frequency and severity. The number of overuse injuries sustained over a 5-year period did not differ between OD and IR. However, the proportions of OD and IR athletes who were affected by injury to particular anatomical sites differed (p < 0.05). Also, fewer OD athletes (16.7 vs. 36.8%, p < 0.05) reported that their injury recurred. Although OD sustained fewer running injuries than IR (1.6 +/- 0.5 vs. 1.9 +/- 0.3, p < 0.05), more subsequently stopped running (41.7 vs. 15.8%) and for longer (33.5 +/- 43.0 vs. 16.7 +/- 16.6 days, p < 0.01). In OD, the number of overuse injuries sustained inversely correlated with percentage training time, and number of sessions, doing bike hill repetitions (r = -0.44 and -0.39, respectively, both p < 0.05). The IR overuse injury number correlated with the amount of intensive sessions done (r = 0.67, p < 0.01 and r = 0.56, p < 0.05 for duration of "speed run" and "speed bike" sessions). Coaches should note that training differences between triathletes who specialize in OD or IR competition may lead to their exhibiting differential risk for injury to specific anatomical sites. It is also important to note that cycle and run training may have a "cumulative stress" influence on injury risk. Therefore, the tendency of some triathletes to modify rather than stop training when injured-usually by increasing load in another discipline from that in which the injury first occurred-may increase both their risk of injury recurrence and time to full rehabilitation.

Whole-body vibration training: metabolic cost of synchronous, side-alternating or no vibrations.

Whole-body vibration training improves strength and can increase maximal oxygen consumption ([·V]O(2max)). No study has compared the metabolic demand of synchronous and side-alternating whole-body vibration. We measured [·V]O₂ and heart rate during a typical synchronous or side-alternating whole-body vibration session in 10 young female sedentary participants. The 20-min session consisted of three sets of six 45-s exercises, with 15 s recovery between exercises. Three conditions were randomly tested on separate days: synchronous at 35 Hz and 4 mm amplitude, side-alternating at 26 Hz and 7.5 mm amplitude (peak acceleration matched at 20 g in both vibration conditions), and no vibrations. Mean [·V]O₂ (expressed as %[·V]O(2max)) did not differ between conditions: 29.7 ± 4.2%, 32.4 ± 6.5%, and 28.7 ± 6.7% for synchronous, side-alternating, and no vibrations respectively (P = 0.103). Mean heart rate (% maximal heart rate) was 65.6 ± 7.3%, 69.8 ± 7.9%, and 64.7 ± 5.6% for synchronous, side-alternating, and no vibrations respectively, with the side-alternating vibrations being significantly higher (P = 0.019). When analysing changes over exercise sessions, mean [·V]O₂ was higher for side-alternating (P < 0.001) than for synchronous and no vibrations. In conclusion, side-alternating whole-body vibration elicits higher heart rate responses than synchronous or no vibrations, and could elevate [·V]O₂, provided the session lasts more than 20 min.

Vibration Training Elicits a Mixed Aerobic and Resistance-type Exercise in Sedentary Subjects

PURPOSE: We hypothesize that untrained subjects can benefit from a greater cardiovascular stimulation than trained athletes, resembling classical aerobic-type activity, in addition to eliciting strength gains.METHODS: 3 groups of male subjects, inactive (SED), endurance trained (END) and strength trained (STR) underwent fitness (VO2max) and lower-body strength tests (isokinetic). Subjects were submitted to a session of oscillating VT, composed of 3 exercises (isometric half-squat, dynamic squat, dynamic squat with added load), each of 3 minutes duration, and repeated at 3 vibration frequencies (20, 26 and 32 Hz). VO2, heart rate and Borg scale were monitored.RESULTS: 27 healthy subjects (10 SED, 9 END and 8 STR), mean age 24.5 (SED), 25.0 (STR) and 29.8 (END) were included. VO2max was significantly different as expected (47.9 vs. 52.9 vs. 63.9 mL?min-1?kg-1, resp. for SED, STR and END). Isokinetic dominant leg extensors strength was higher in STR (3.32 N?m?kg-1 vs. 2.60 and 2.74 in SED and END). During VT, peak oxygen consumption (% of VO2max) attained was 59.3 in SED, 50.8 in STR and 48.0 in END (P<0.001 between SED and other subjects). Peak heart rate (% of heart rate max) was 82.7 in SED, 80.4 in STR and 72.4 in END. In SED, dynamic exercises without extra load elicited 51.0 % of VO2max and 72.1 % of heart rate max, and perceived effort reached 15.1/20.CONCLUSIONS: VT is an unconventional type of exercise, known to enhance strength, bone density, balance and flexibility. Users are attracted by the relative passivity. In SED, VT elicits sufficient cardiovascular response to benefit overall fitness in addition to the strength effects. VT's higher acceptance as an exercise in sedentary people, compared to jogging or cycling, can lead to better adherence to physical activity. Although long-term effects of VT on health are not available, we believe this type of mixed aerobic and resistance-type exercise can be beneficial on multiple health parameters, especially cardiovascular health.

Influence on Strength and Flexibility of a Swing Phase-Specific Hamstring Eccentric Program in Sprinters' General Preparation

Guex, KJ, Lugrin, V, Borloz, S, and Millet, GP. Influence on strength and flexibility of a swing phase-specific hamstring eccentric program in sprinters' general preparation. J Strength Cond Res 30(2): 525-532, 2016-Hamstring injuries are common in sprinters and mainly occur during the terminal swing phase. Eccentric training has been shown to reduce hamstring injury rate by improving several risk factors. The aim of this study was to test the hypothesis that an additional swing phase-specific hamstring eccentric training in well-trained sprinters performed at the commencement of the winter preparation is more efficient to improve strength, ratio, optimum angle, and flexibility than a similar program without hamstring eccentric exercises. Twenty sprinters were randomly allocated to an eccentric (n = 10) or a control group (n = 10). Both groups performed their usual track and field training throughout the study period. Sprinters in the eccentric group performed an additional 6-week hamstring eccentric program, which was specific to the swing phase of the running cycle (eccentric high-load open-chain kinetic movements covering the whole hamstring length-tension relationship preformed at slow to moderate velocity). Isokinetic and flexibility measurements were performed before and after the intervention. The eccentric group increased hamstring peak torques in concentric at 60 degrees .s by 16% (p < 0.001) and at 240 degrees .s by 10% (p < 0.01), in eccentric at 30 degrees .s by 20% (p < 0.001) and at 120 degrees .s by 22% (p < 0.001), conventional and functional ratios by 12% (p < 0.001), and flexibility by 4 degrees (p < 0.01), whereas the control group increased hamstring peak torques only in eccentric at 30 degrees .s by 6% (p </= 0.05) and at 120 degrees .s by 6% (p < 0.01). It was concluded that an additional swing phase-specific hamstring eccentric training in sprinters seems to be crucial to address different risk factors for hamstring strain injuries, such as eccentric and concentric strength, hamstring-to-quadriceps ratio ratio, and flexibility.