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This study determined the acute changes in rotational work with thigh attached wearable resistance (WR) of 2% body mass during 50-m sprint-running. Fourteen athletes completed sprints with, and without, WR in a randomised order. Sprint times were measured via timing gates at 10-m and 50-m. Rotational kinematics were obtained over three phases (steps 1–2, 3–6 and 7–10) via inertial measurement unit attached to the left thigh. Quantification of thigh angular displacement and peak thigh angular velocity was subsequently derived to measure rotational work. The WR condition was found to increase sprint times at 10-m (1.4%, effect size [ES] 0.38, p 0.06) and 50-m (1.9%, ES 0.55, p 0.04). The WR condition resulted in trivial to small increases in angular displacement of the thigh during all phases (0.6–3.4%, ES 0.04–0.26, p 0.09–0.91). A significant decrease in angular velocity of the thigh was found in all step phases (−2.5% to −8.0%, ES 0.17–0.51, p < 0.001–0.04), except extension in step phase 1 with the WR. Rotational work was increased (9.8–18.8%, ES 0.35–0.53, p < 0.001) with WR in all phases of the sprint. Thigh attached WR provides a means to significantly increase rotational work specific to sprinting. [ABSTRACT FROM AUTHOR]

Motion of the rear leg during a tennis forehand was previously reported to influence the ball speed. However, impact of a kinetic measure such as the ground-reaction force (GRF) on forehand ball speed has not been investigated. The aim of this study was to investigate the influence of GRF on forehand ball speed and identify the most influential component of GRF related to overall higher ball speeds. Nine tennis players (eight males, one female) were invited to participate. Three testing sessions were conducted. Each session consisted of maximal forehand ball-speed testing and seven forehands at three ball speeds; fast (100%), medium (90%) and slow (80%). GRF and post-impact ball speed were measured for each stroke. Of all the individual GRF vectors, peak anterior-posterior force best explained the changes in ball speed, where 26% (R2 = 0.26) of ball speed variance can be explained by this force vector alone. In a stepwise fashion, adding peak lateral force to the model explained a further 7% (R2 = 0.33). Combining peak anterior-posterior, medial-lateral and vertical forces explained a total of 37% (R2 = 0.37). Peak anterior-posterior force appears to be the most influential ground-reaction force affecting forehand post-impact ball speed. [ABSTRACT FROM AUTHOR]

High-intensity, short-duration warm-up techniques improve acute physical performance, but sparse research has examined their consequence when followed by intermittent activity, which is pertinent to team sports. The authors compared a 5-repetition-maximum (5RM) leg-press, a small-sided game (SSG), and a current team-sport warm-up in 10 semiprofessional soccer players after 2 intermittent-activity protocols consisting of 15 repetitions of a 60-s circuit that included sprinting, slalom, walking, jogging, decelerations, changes of direction, backward running, and striding activities. There was a large improvement in countermovement-jump height in the 5RM after the 1st intermittent-activity protocol (mean, ±90% CL 6.0, ±4.0%, P = .03) and a small improvement after the 2nd (4.6, ±4.0%, P = .04) compared with team sport. Reactive agility was moderately faster via 5RM after the 1st intermittent-activity protocol (3.1, ±2.6%: P = .04) and the 2nd (5.7, ±2.7%, P = .001) than via SSG. There was a small improvement in reactive agility after the 1st intermittent-activity protocol in the 5RM, compared with team sport (3.3, ±2.9%, P = .04). There was a small improvement in mean 20-m-sprint times after both intermittent-activity protocols in the 5RM, compared with SSG (4.2, ±2.0%, P = .01, and 4.3, ±2.0%, P = .01) and, after the 1st intermittent-activity protocol only, compared with team sport (4.2, ±2.1%, P = 0.02). Small increases in blood lactate concentration were observed (46.7, ±18.6%, P = .01) in the 5RM compared with the SSG after the 2nd intermittent-activity protocol. Improved performances after the 5RM warm-up should encourage practitioners to reduce activity time and include high-intensity tasks in team-sport warm-ups aimed at inducing a potentiating effect. [ABSTRACT FROM AUTHOR]

Pacing profiles of 19 elite and sub-elite 200-m kayak athletes were examined through stroke-by-stroke analysis, using GPS/accelerometer methodology. Stroke rates and lengths were also quantified across multiple race segments. Whilst athletes reached peak velocity at between 40 and 60 m, it was not possible to determine specifically whether an all-out or positive strategy was employed. Race times were strongly and negatively correlated with the acceleration over the first ~25% of race distance (r = −0.95 ± 0.04) as well as average velocity over the first 30 m of the race (r>-0.9), i.e. faster starts were associated with faster finishing times. Furthermore, the maintenance of velocity, stroke rate and stroke length after reaching their maxima were strongly associated with race times. Stroke rates were higher (Cohen's d = 5.19) in the elite than sub-elite athletes (group categorisation based on race times), but there were no substantial differences in stroke rates between athletes within the elite cohort. Nonetheless, longer stroke lengths were associated with faster race times within the elite cohort (r = −0.48 to −0.85). The current study suggests that faster rates of acceleration and the ability to exhibit greater stroke lengths at relatively high stroke rates are determinants of 200-m kayak race performance. [ABSTRACT FROM AUTHOR]

Horizontal force-velocity (F-V) profiling is a strategy to assess athletes' individual performance capabilities during sprinting. This study investigated the acute changes in F-V profiles during sprinting of fourteen collegiate male sprinters with a mean 100-m sprint time of 11.40 ± 0.39 s, from a split-stance starting position. The subjects sprinted 30-m with, and without, wearable resistance (WR) equivalent to 2% body mass, attached to their forearms. Sprinting time at 5, 10, 20, and 30-m was assessed using laser technology. External horizontal F-V relationships were calculated via velocity-time signals. Maximal theoretical velocity (V0), theoretical relative and absolute horizontal force (F0), and horizontal power (Pmax) were determined from the F-V relationship. Paired t-tests were used to determine statistical differences (p ≤ 0.05) in variables across conditions with Cohen's d as effect sizes (ES) calculated to assess practical changes. Sprint times at 10-m and beyond were significantly increased (1.9–3.3%, p 0.01–0.03, ES 0.46–0.60) with WR compared to unloaded sprinting. The only significant change in F-V with the WR condition was found in relative Pmaxsystem (−6.1%, p 0.01, ES 0.66). A small decrease was reported in V0 (−1.0%, p 0.11, ES 0.27), with small to medium ES decreases reported in F0 (−4.8% to −6.1%, p 0.07–0.21, ES 0.25-0.51) and Pmax (−4.3% to −4.6%, p 0.06–0.08, ES 0.32–0.45). The greater changes to F0 and Pmax suggest that forearm WR may be a possible training tool for athletes who wish to focus on force and power adaptation during sprint acceleration from a standing start. [ABSTRACT FROM AUTHOR]

This study investigated the effect of Vibram footwear, during a five-week training program on change-of-direction speed performance. Junior Australian Rules Footballers (n=20) were stratified into a Vibram shoe (n=9) and control shod group (n=11). Pre-post measurements of change-of-direction speed, extrinsic foot strength (plantar flexion) and intrinsic foot strength (greater toe flexion and lesser toe flexion) were examined. To determine the sensitivity of the effect, data were analysed using effect size (ES) statistics (90% CL) and percentage change. Vibram shoes provided a 'likely beneficial' improvement compared to control in the AFL agility test (-2.3% greater improvement, ES 0.38) including an 'unclear' enhancement in the agility T-test (-1.9%, ES 0.41), and a 'possibly trivial' change for the Pro agility shuttle (-0.1%, ES 0.01). Intrinsic foot strength showed an 'unclear' effect for both groups (greater toe flexion 8.3 ± 24.0%, ES:0.20 right and 19.2 ± 32.4%, ES:0.40 left lesser toe flexion 11.1 ± 30.4%, ES:0.20 right and 10.9 ± 36.1%, ES:0.23 left). Effects of the intervention on extrinsic foot strength were 'unclear' (plantar flexion -10.4 ± 18.5%, ES:0.43 right and -9.0 ± 13.1%, ES:0.29 left). Junior Australian Rules Footballers experienced 'likely beneficial' improvements with Vibram footwear for the AFL agility test greater than the control group. The effect of Vibram footwear on intrinsic and extrinsic foot strength was 'unclear' in the current cohort and warrants further investigation. These findings provide important information for coaches and athletes for the use of Vibram/minimalist footwear training for the improvement of sport-specific physical capacities with team-sport athletes. [ABSTRACT FROM AUTHOR]

Evidence suggests that static stretching inhibits muscular power. However, research does not reflect practice whereby individuals follow up stretching with secondary activity. This study investigated muscular power following stretching, and after a second bout of activity. Participants (n = 13) completed 3 randomized testing sessions which included a 5 min warm-up, followed by a vertical jump (VJ) on a force platform; an intervention (static stretching, dynamic, or control), followed by a second VJ. Participants then completed a series of movements, followed by a VJ, up to 60 min post activity. Immediately following the intervention, there was a 10.7% difference in VJ between static and dynamic stretching. The second warm up bout increased VJ height following the dynamic intervention, whereas the static stretching condition did not show any differences. The novel finding from this study demonstrates a second exercise bout does not reverse the effects of static stretching and is still detrimental to VJ. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Enhanced lower-limb drive following acute warm-ups can increase counter-movement jump (CMJ) height, power output and sprint performance. However, the effects of high-intensity, short-duration warm-ups during the tennis serve are unknown. This study examined the effect of three post-activation potentiation (PAP) protocols on tennis serve velocity and accuracy. Despite the potential benefits of utilising PAP protocols during warm-ups, limited research has examined if lower-limb potentiation can be transferred through the kinetic chain to influence whole-body skill execution tasks. METHODS: Eight sub-elite tennis players (four male and four female), competing in national level tournaments each performed three sets of three parallel back-squats at 80% of 1-repetition-maximum, weighted counter-movement jump (CMJ) and band squats. Interventions were administered on separate days in a counterbalanced, crossover design. Following each PAP protocol, participants completed 24 tennis serves separated into four sets of six serves standing on a force platform. Ball velocity, service accuracy and ground-reaction forces (GRF) were measured. All variables were log-transformed. Log-transformed data were analyzed and expressed as standardized units (effect sizes) via Hopkins spreadsheets with uncertainty in changes expressed as 95% confidence intervals and interpreted using the non-clinical magnitude-based inference approach. RESULTS: The impact of PAP interventions on GRF was either unclear, trivial, or possibly negative. The effect of weighted CMJ and band trials on ball velocity was trivial compared to control (CMJ: -1.3 ± 1.4%; ES -0.08 ± 0.08; and band: -1.2 ± 2.3%; ES -0.07 ± 0.14), while the squat intervention had a possible negative effect compared to control (-3.5 ± 3.2%; ES -0.41 ± 0.20). The effect of PAP protocols on mean force was unclear (CMJ: 3.2 ± 13.8%; ES 0.11 ± 0.47; and squat: 5.2 ± 18.4%; ES 0.18 ± 0.61) or trivial (band: -3.1 ± 6.2%; ES -0.11 ± 0.22). DISCUSSION: Warm-up interventions used in this study did not improved service velocity, nor GRF in a sub-elite tennis cohort, whilst changes to service accuracy were unclear throughout trials. A combination of sub-optimal strength level, transfer of energy through kinetic chain and service proficiency may have contributed to these results. However, individual data suggest that participants with higher levels of strength training and service efficacy may be able to realize performance benefits via PAP. Further research with tennis players that display a highly efficient service action and have >1.75 back squat: body-mass ratio is warranted. PRACTICAL APPLICATIONS: This study reported that junior elite tennis players should focus on tennis-specific WU routines that do not include PAP focused warm-ups. Further research is warranted in its application to elite cohorts with highly refined skill sets, greater relative strength (back squat: body-mass ratio >1.75) and effective kinetic chain force transfer during service action. Establishing practical PAP interventions and individual recovery periods that can cause minimal fatigue to tennis athletes whilst maximizing potentiation, necessitates further investigation. [ABSTRACT FROM AUTHOR]

Introduction: This review aimed 1) to evaluate the current research that examines the efficacy of warm-up (WU) and re-warm-up (RWU) on physical performance; and 2) to highlight the WU and RWU characteristics that optimise subsequent performance in soccer players., Evidence Acquisition: A computerized search was performed in the PubMed, ScienceDirect and Google Scholar (from 1995 to December 2015) for English-language, peer-reviewed investigations using the terms "soccer" OR "football" AND "warm-up" OR "stretching" OR "post-activation potentiation" OR "pre-activity" OR "re-warm-up" AND "performance" OR "jump" OR "sprint" OR "running"., Evidence Synthesis: Twenty seven articles were retrieved. Particularly, 22 articles examined the effects of WU on soccer performance and 5 articles focused on the effects of RWU. Clear evidence exists supporting the inclusion of dynamic stretching or postactivation potentiation-based exercises within a WU as acute performance enhancements were reported (pooled estimate changes of +3.46% and +4.21%, respectively). The FIFA 11+ WU also significantly increases strength, jump, speed and explosive performances (changes from 1% to 20%). At half-time, active RWU protocols including postactivation potentiation practices and multidirectional speed drills attenuate temperature and performance reductions induced by habitual practice. The data obtained in the present review showed that the level of play did not moderate the effectiveness of WU and RWU on soccer performance., Conclusions: This review demonstrated that a static stretching WU reduced acute subsequent performance, while WU activities that include dynamic stretching, PAP-based exercises, and the FIFA 11+ can elicit positive effects in soccer players. The efficacy of an active RWU during half-time is also justified.