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Athletes use postexercise hydrotherapy strategies to improve recovery and competition performance and to enhance adaptative responses to training. Using a randomized cross-over design, the acute effects of 3 postresistance exercise water immersion strategies on perceived recovery, neuromuscular performance, and hormone concentrations in junior international and subelite male volleyball athletes (n = 18) were investigated. After resistance exercise, subjects randomly completed either 15-minute passive control (CON), contrast water therapy (CWT), cold (CWI), or hot water immersion (HWI) interventions. A treatment effect occurred after HWI; reducing perceptions of fatigue (HWI > CWT: p = 0.05, g = 0.43); improved sleep quality, compared with CON (p < 0.001, g = 1.15), CWI (p = 0.017, g = 0.70), and CWT (p 5 0.018, g 5 0.51); as well as increasing testosterone concentration (HWI > CWT: p = 0.038, g = 0.24). There were trivial to small (p < 0.001-0.039, g = 0.02-0.34) improvements (treatment effect) in jump performance (i.e., squat jump and counter- movement jump) after all water immersion strategies, as compared with CON, with high variability in the individual responses. There were no significant differences (interaction effect, p > 0.05) observed between the water immersion intervention strategies and CON in performance (p = 0.153-0.99), hormone (p = 0.207-0.938), nor perceptual (p = 0.368-0.955) measures. To optimize recovery and performance responses, e.g., during an in-season competition phase, postresistance exercise HWI may assist with providing small-to-large improvements for up to 38 hours in perceived recovery (i.e., increased sleep quality and reduced fatigue) and increases in circulating testosterone concentration. Practitioners should consider individual athlete neuromuscular performance responses when prescribing postexercise hydrotherapy. These findings apply to athletes who aim to improve their recovery status, where postresistance exercise HWI optimizes sleep quality and next-day perceptions of fatigue. [ABSTRACT FROM AUTHOR]

Athletes use water immersion strategies to recover from training and competition. This study investigated the acute effects of postexercise water immersion after resistance exercise. Eighteen elite and subelite male volleyball athletes participated in an intervention using a randomized cross-over design. On separate occasions after resistance exercise, subjects completed 1 of 4 15-minute interventions: control (CON), cold water immersion (CWI), contrast watertherapy (CWT), or hot water immersion (HWI). Significance was accepted at p # 0.05. Resistance exercise induced significant temporal changes (time effect) for inflammatory, anthropometric, perceptual, and performance measures. Serum creatine kinase was reduced (g = 0.02-0.30) after CWI (p = 0.007), CWT (p = 0.006), or HWI (p < 0.001) vs. CON, whereas it increased significantly (g = 0.50) after CWI vs. HWI. Contrast water therapy resulted in significantly higher (g = 0.56) interleukin-6 concentrations vs. HWI. Thigh girth increased (g = 0.06-0.16) after CWI vs. CON (p = 0.013) and HWI (p < 0.001) and between CWT vs. HWI (p = 0.050). Similarly, calf girth increased (g = 0.01-0.12) after CWI vs. CON (p = 0.039) and CWT (p = 0.018), and HWI vs. CON (p = 0.041) and CWT (p = 0.018). Subject belief in a postexercise intervention strategy was associated with HSP72 ("believer">"nonbeliever," p = 0.026), muscle soreness ("believer">"nonbeliever," p = 0.002), and interleukin-4 ("nonbeliever">"believer," p = 0.002). There were no significant treatment x time (interaction effect) pairwise comparisons. Choice of postexercise water immersion strategy (i.e., cold, contrast, or hot) combined with a belief in the efficacy of that strategy to enhance recovery or performance improves biological and perceptual markers of muscle damage and soreness. On same or subsequent days where resistance exercise bouts are performed, practitioners should consider athlete beliefs when prescribing postexercise water immersion, to reduce muscle soreness. [ABSTRACT FROM AUTHOR]

Purpose: To establish the influence of athlete-dependent characteristics on the generation and timing of system and individual joint powers during a countermovement jump (CMJ). Methods: Male national representative athletes from volleyball (n = 7), basketball (n = 6), and rugby (n = 7) performed a set of 3 CMJs at relative barbell loads of 0%, 10%, 20%, 30%, and 40% of absolute back-squat strength. Ground-reaction forces and joint kinematics were captured using a 16-camera motion-capture system integrated with 2 in-ground force plates. Limb lengths and cross-sectional areas were defined using 3-dimensional photonic scans. A repeated-measures analysis of variance determined the interaction between system and joint load–power profiles, whereas a multiregression analysis defined the explained variance of athlete-dependent characteristics on the load that maximized system power. Results: System and isolated hip, knee, and ankle peak powers were maximized across a spectrum of loads between and within sports; power values were not significantly different across loads. A positive shift in the timing of hip and ankle peak powers corresponded to a significant (P <.05) positive shift in the timing of system peak power to occur closer to toe-off. An optimal 3-input combination of athlete-dependent characteristics accounted for 68% (P <.001) of the explained variance in the load that maximized system peak power. Conclusion: The load maximizing system power is athlete-dependent, with a mixture of training and heredity-related characteristics influencing CMJ load–power profiles. The authors recommend that a combination of relative loads be individually prescribed to maximize the generation and translation of system CMJ power. [ABSTRACT FROM AUTHOR]

Everett, KLA, Chapman, DW, Mitchell, JA, and Ball, N. Changes in loaded countermovement jumps during precompetition and competition training mesocycles in elite rowers. J Strength Cond Res 36(9): 2622–2627, 2022—To assess changes in velocity, displacement, and power as an indicator of neuromuscular fatigue (NMF) within and between precompetition and competition mesocycles in elite male rowers using loaded countermovement jumps (CMJs). Twenty highly trained rowers completed regular training (on-water rowing, rowing ergometer, and resistance training sessions) in 2 consecutive mesocycles. Athletes completed a single set of 6 loaded (20 kg) CMJs in the first and final week of each mesocycle. Countermovement jumps were assessed for jump height (JH), eccentric displacement, mean velocity (MV), eccentric MV (EMV), and mean power. Changes between time points were reported as Cohen's d effect sizes (95% confidence interval [CI]). The magnitude of the differences was also considered based on their relative strength levels using a linear mixed model. Within the precompetition mesocycle, trivial-to-small reductions for all variables (0.5–4.1%) were observed. During the competition mesocycle, trivial-to-small increases were shown for EMV (1.4%) and eccentric displacement (2.0%) with no change in JH and small reductions in MV (0.5%) and mean power (2.8%). No differences between the precompetition and competition mesocycles were shown. Only mean power showed a significant reduction in weaker athletes (3.2%) compared with stronger athletes (2.3%). Training completed during a precompetition and competitive mesocycle did not result in significant decreases in athlete's loaded CMJ performance, indicating that NMF was minimized. Alternatively, use of a loaded CMJ may not be sensitive enough to observe NMF in elite rowers during the mesocycle immediately leading into and during a competition mesocycle. [ABSTRACT FROM AUTHOR]

The purpose ot this study was to calculate the coefficients of variation in jump performance for individual participants in multiple trials over time to determine the extent to which there are real differences in the error of measurement between participants. The effect of training phase on measurement error was also investigated. Six subjects participated in a resistance-training intervention for 12 wk with mean power from a countermovement jump measured 6 d/wk. Using a mixed-model meta-analysis, differences between subjects, within-subject changes between training phases, and the mean error values during different phases of training were examined. Small, substantial factor differences of I. I I were observed between subjects; however, the finding was unclear based on the width of the confidence limits. The mean error was clearly higher during overload training than baseline training, by a factor of x/+ 1.3 (confidence limits 1.0-1.6). The random factor representing the interaction between subjects and training phases revealed further substantial differences of x/h- 1.2 (1.1-1.3), indicating that on average, the error of measurement in some subjects changes more than in others when overload training is introduced. The results from this study provide the first indication that within-subject variability in performance is substantially different between training phases and, possibly, different between individuals. The implications of these findings for monitoring individuals and estimating sample size are discussed. [ABSTRACT FROM AUTHOR]

Initial short-track speed-skating 14-m start performance has substantial influence on 500-m race outcome at the international level, yet the relationship has not been systematically quantified. The purpose of this investigation was to examine the relationship between rank position entering first corner (RPEFC) and race outcome and to understand how this relationship changes with competition round and absolute race intensity. Data were compiled from 2011-2014 World Cup seasons and 2010 and 2014 Olympic Winter Games. Association between RPEFC and race outcome was determined through Kendall tau-rank correlations. A visual comparison was made of how the relationship changes with relative competition level (race tau correlations were sorted by competition round) and with race intensity (race tau correlations were sorted by within-event winning time). A very large relationship between RPEFC and race outcome was observed (correlations for cohort, τ = .60; men, τ = .53; women, τ = .67). When examined by competition round (quarter- to A-finals), no substantial change in relationship was observed (men, τ = .57-.46; women, τ = .73-.53). However, when the start-performance relationship was considered by within-event winning time, the relationship strength increased with decreasing time (men, τ = .61 to .46; women, τ = .76 to .57; fastest to 7th- and 8th-fastest combined, respectively). These results establish and quantify RPEFC as an important aspect of elite short-track 500-m race outcome. RPEFC as an indicator of race outcome becomes increasingly important with absolute race intensity, suggesting that RPEFC capability is a discriminating factor for competitors of similar top speed and speed endurance. [ABSTRACT FROM AUTHOR]

Countermovement jumps loaded with a weighted vest are often used for the training of lower body power to improve jump performance. However, it is currently unknown how this added load affects the lower extremity kinematics and kinetics, in particular whether this results in an increased injury risk. Therefore, the purpose of this investigation was to determine how lower extremity kinematics and kinetics during landing are affected by loaded jumps as demonstrated in a volleyball block jump landing. Ten elite male volleyball players performed block jump landings in an unloaded and loaded (9.89 kg) condition. Kinematic and kinetic landing data from the three highest jumps were collected and assessed. Paired samples t test was used to establish whether load condition had a significant effect on lower extremity kinematics and kinetics. Hip flexion was significantly greater in the unloaded condition compared with the loaded condition (p = .004). There was no significant difference in any other kinematic or kinetic variables measures between the unloaded and loaded conditions. These results suggest that landing from loaded volleyball block jumps does not increase injury risk compared with unloaded jumps in elite male volleyball players. [ABSTRACT FROM AUTHOR]

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 4-week training intervention. Before and after the control and intervention periods, athletes performed 3 electronically timed dry-land and on-ice 14.43 m maximal sprint start efforts. The intervention consisted of 2 sprint sessions per week consisting of 9 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 seconds, 95% confidence limit [CL]: -0.08 to 0.05 seconds; effect size [ES]: -0.05; trivial); however, a small change was observed in dry-land start performance (mean Δ: -0.07 seconds, 95% CL: -0.13 to -0.02 seconds; ES: -0.49). After brief specific dry-land sprint start training, a small improvement was observed in both on-ice (Mean Δ: -0.07 seconds, 95% CL: -0.13 to -0.01 seconds; ES: -0.33) and dry-land (Mean Δ: -0.04 seconds, 95% CL: -0.09 to 0.00 seconds; ES: -0.29) start performance. This investigation suggests that STSS start performance can be improved through a brief dry-land sprint start training program. [ABSTRACT FROM AUTHOR]

This study aimed to investigate whether hip, knee, and ankle peak power is influenced by the relative load lifted, altering the joint and system load-power relationship during a countermovement jump (CMJ). Twenty-three male national representative athletes (age: 20.3 ± 3.1 years, squat 1 repetition maximum [1RM]: 133.8 ± 24.8 kg) completed 3 CMJs at relative barbell loads of 0, 10, 20, 30, and 40% of an athlete's estimated back squat 1RM. Ground reaction force and joint kinematics were captured using a 16 camera motion capture array integrated with 2 in-ground triaxial force plates. Hip ((Equation is included in full-text article.)= 20%, range 0 > 40%), knee ((Equation is included in full-text article.)= 0%, 0 > 20%), and ankle ((Equation is included in full-text article.)= 40%, 0 > 40%) peak power was maximized at different percentages of absolute strength, with an athlete-dependent variation in load-power profiles observed across all lower-body joints. A decrease in system (body + barbell mass) peak power was significantly (p ≤ 0.05, r = 0.45) correlated with a reduction in knee peak power. Timing of instantaneous system and hip peak power occurred significantly closer to toe-off as load increased. The findings highlight that the generation and translation of lower-body joint power is influenced by external load and athlete-dependent traits. This subsequently alters the load-power profile at a system level, explaining the broad spectrums of loads reported to optimize system power during a CMJ. When training, we recommend that a combination of barbell loads based on assorted percentages of the estimated 1RM be prescribed to optimize joint and system power during a CMJ. [ABSTRACT FROM AUTHOR]

The investigation sought to describe the current practices for monitoring and maximising power in the discipline of strength and conditioning. Thirty professional strength and conditioning coaches working within a national institute network agreed to complete a short online survey. Questions were posed in the areas of exercise and equipment selection, methods of calculation, load prescription, and measures of jump performance. The majority of respondents (67%) reported that a countermovement jump (CMJ) was their preferred exercise to monitor lower body neuromuscular performance. However, there was no consistency in the equipment, calculation methods, or loads prescribed to monitoring or maximise power during a CMJ. Additionally, more than half of respondents preferred measures of force, velocity, and jump height over external estimates of power to quantify CMJ performance. The investigation highlights a discrepancy in assessment techniques, calculation methods, and loads prescribed to monitor or maximise power. These findings are in contrast to anecdotal support for the use of and programming for power in published literature. Consequently, practitioners are recommended to continue in their use of direct kinetic and kinematic measures to assess neuromuscular performance, as they are practically obtainable, empirically supported, and easy to communicate. Furthermore, practitioners and researchers must also attempt to understand where the disconnect between theory and applied practice lies in order to improve the transference of research findings into applied practice. [ABSTRACT FROM AUTHOR]

This study aimed to (1) profile a professional boxer (23 years and 80 kg) with boxing-specific, muscle function, aerobic capacity and body composition tests, and (2) quantify how these measures varied during an 8-week preparation phase leading to, and post a state-Title Bout fought in the 76.2-kg class. A series of boxing-specific and muscle function tests were completed on 11 occasions: 9 prior and twice after the bout, each separated by approximately 2 weeks. The boxing test included 36 maximal punches (9 of each: lead and rear straights, lead and rear hooks) to a punching integrator measuring forces and velocity. Muscle function tests included countermovement jump, drop-jumps, isometric mid-thigh pull and isometric bench-press. Body composition was assessed using skin-fold measurements on three occasions and one dual energy X-ray absorptiometry scan. Aerobic capacity was assessed using 2 VO2M max tests. Leading up to the bout, performance decreased in isometric mid-thigh pull (8%), isometric bench-press (5%), countermovement jump (15%) and impact forces in 3 of 4 punches (4%-7%). Whereas measures of dynamic and isometric muscle function remained depressed or unchanged post competition, punching forces (6%-15%) and aerobic power (6%) increased. Data suggest the athlete may have super-compensated following rest as fatigue dissipated and further adaptation occurred. [ABSTRACT FROM AUTHOR]

Micro-sensors were used to quantify macro kinematics of classical cross-country skiing techniques and measure cycle rates and cycle lengths during on-snow training. Data were collected from seven national level participants skiing at two submaximal intensities while wearing a micro-sensor unit (MinimaxX™). Algorithms were developed identifying double poling (DP), diagonal striding (DS), kick-double poling (KDP), tucking (Tuck), and turning (Turn). Technique duration (T-time), cycle rates, and cycle counts were compared to video-derived data to assess system accuracy. There was good reliability between micro-sensor and video calculated cycle rates for DP, DS, and KDP, with small mean differences (Mdiff% = −0.2 ± 3.2, −1.5 ± 2.2 and −1.4 ± 6.2) and trivial to small effect sizes (ES = 0.20, 0.30 and 0.13). Very strong correlations were observed for DP, DS, and KDP for T-time (r = 0.87–0.99) and cycle count (r = 0.87–0.99), while mean values were under-reported by the micro-sensor. Incorrect Turn detection was a major factor in technique cycle misclassification. Data presented highlight the potential of automated ski technique classification in cross-country skiing research. With further refinement, this approach will allow many applied questions associated with pacing, fatigue, technique selection and power output during training and competition to be answered. [ABSTRACT FROM PUBLISHER]

The article identifies differences in end range of motion (ROM) kinetic and kinematic strategies between highly resistance and vertical jump-trained athletes and controls. Identifying differences in end ROM jump kinetics and kinematics between groups may expose particular mechanismse. This may improve vertical jump performance and present weightlifting as a more effective modality of power development as compared with jump and resistance training alone.

The article cites a research study which examined the effect of rest interval duration on muscular power production in the lower body power profile. The study subjects were ten physically trained men who completed four experimental conditions in a crossover balanced design. The study found insubstantial differences in power output across incremental loads between the 1- to 4-minute rest interval conditions.

To determine if post-activation potentiation (PAP) can augment sports performance, it is pertinent that researchers be confident that any enhancement in performance is attributable to the PAP phenomenon. However, obtaining mechanistic measures of PAP in the daily training environment of highly trained athletes is impractical. We sought to validate jump squats as a practical measure with ecological validity to sports performance against a mechanistic measure of PAP. We assessed the evoked muscle twitch properties of the knee extensors and jump squat kinetics of 8 physically trained males in response to a 5-repetition-maximum back squat conditioning stimulus (CS). Evoked muscle twitch, followed by 3 jump squats, was assessed before and at 4, 8, and 12 min post CS. Time intervals were assessed on separate occasions using a Latin square design. Linear regression was used to determine the relationship between post-pre changes in kinetic variables and muscle twitch peak force (Ft) and twitch rate of force development (RFDt). Large correlations were observed for both concentric relative and absolute mean power and Ft ( r = 0.50 ± 0.30) and RFDt ( r = 0.56 ± 0.27 and r = 0.58 ± 0.26). Concentric rate of force development (RFD) showed moderate correlations with Ft ( r = 0.45 ± 0.33) and RFDt ( r = 0.49 ± 0.32). Small-to-moderate correlations were observed for a number of kinetic variables ( r = −0.42-0.43 ± 0.32-0.38). Jump squat concentric mean power and RFD are valid ecological measures of muscle potentiation, capable of detecting changes in athletic performance in response to the PAP phenomenon. [ABSTRACT FROM AUTHOR]

The article discusses research conducted in an effort to identify the peak mechanical power (Pmax) load ('optimal load') in the jump squat and to quantify small, moderate, large, and very large substantial differences in power output across a spectrum of loads to identify loads that are substantially different to the optimal, and lastly, to investigate the nature of power production (load-force-velocity profiles) in football and rugby players. Researchers were able to identify the load.

The article reports on research which was conducted to investigate the potential association with anthropometry and upper-body pulling strength with sprint kinematics of competitive surfers. Researchers evaluated 10 competitive male surfers. They found that there was a strong association between relative upper-body pulling strength and sprint paddling ability in surfers and concluded that coaches working with competitive surfers should implement strength training with the surfers.

The article presents the results of a study which investigated the muscle damage induced by differing velocities of eccentric exercise, a strength training technique in which the muscles are lengthened while contracting against a weight which exceeds their strength. An overview of related previous research is provided, along with details of the experimental protocol, which used slow-speed exercise to induce a repeated bout effect prior to high-velocity eccentric exercise.

INTRODUCTION: Hydrotherapy strategies such as cold, hot and contrast water immersion are used by athletes on completion of, and in preparation for, training and competition. The current study investigated the acute (<36 h) effects of post-exercise hydrotherapy on lower-body performance following a whole-body resistance exercise session. METHODS: Junior, international, male, volleyball athletes (n=15, 19.8 ± 3.7 y, 192.5 ± 11.8 cm, 80.2 ± 8.4 kg) were assessed for squat jump (SJ), counter-movement jump (CMJ) and isometric mid-thigh pull (IMTP) performance before and after a single whole-body resistance exercise and post-exercise hydrotherapy session. Athletes completed one of four 15min recovery strategies (control [CON]: passive seated rest at 23.7 ± 0.4°C; cold water immersion [CWI]: 14.8 ± 0.2°C; contrast water therapy [CWT]: 7 x 2 min, alternating hot 39.1 ± 0.5°C and cold 14.8 ± 0.2°C; and hot water immersion [HWI]: 39.1 ± 0.5°C), in a randomised crossover design, with >96 h between trials. SJ, CMJ and IMTP performance was assessed pre (-8 h) and at 0, 2, 4, 12 and 36 h post-resistance exercise. Mean percent change (%Δ) was calculated using a post-exercise (0 h) baseline. Jump height and vertical velocity was determined for SJ (SJ-HT%Δ and SJ-VEL%Δ) and CMJ (CMJ-HT%Δ and CMJ-VEL%Δ). Absolute (IMTP-PF%Δ) and relative (IMTP-relPF%Δ) peak force was determined for IMTP. Eccentric Utilization Ratio (EUR) and Dynamic Strength Index (DSI_SJ:IMTP and DSI_CMJ:IMTP) was calculated. Repeated-measures ANOVA was used to analyse main and interaction effects with significance accepted at p<0.10. The magnitude of change is interpreted using partial eta squared (ƞ²) and Cohen d effect size statistics. RESULTS: No significant main interactions were observed for SJ and CMJ variables (SJ-HT%Δ: p=0.679, ƞ²=0.039; SJ-VEL%Δ: p=0.642, ƞ²=0.041; CMJ-HT%Δ: p=0.545, ƞ²=0.043; CMJ-VEL%Δ: p=0.527, ƞ²=0.045). A significant main interaction was observed for IMTP-relPF%Δ (p=0.095, ƞ²=0.086) with relative IMTP peak force significantly (p=0.09, d=0.41) lower 12 h post-exercise in CWI (367.0 ± 52.6 N.kg-1) vs HWI (388.4 ± 60.1 N.kg-1), however there was no significant main interaction in IMTP-PF%Δ (p=0.43, ƞ²=0.051). No significant main interactions were observed for EUR (p=0.777, ƞ²=0.03), DSI-SJ:IMTP (p=0.242, ƞ²=0.083) or DSI-CMJ:IMTP (p=0.224, ƞ²=0.065). DISCUSSION: Previous research is inconsistent on the application of CWI as a post-exercise recovery strategy, with negative and positive effects on subsequent muscular performance. This research suggests that hydrotherapy strategies such as CWI and CWT do not appear to substantially influence post-exercise changes in SJ, CMJ and IMTP for <36 h following a single bout of resistance exercise. However, HWI optimises maximum isometric strength when compared with CWI at 12 h post-resistance exercise. PRACTICAL APPLICATION: Choice of hydrotherapy strategy may influence muscular contractions for up to 36 h post-exercise with small to medium interaction effects observed in dynamic strength indices. On days where multiple, same day resistance exercise bouts are performed, this data suggests that hydrotherapy would not be beneficial in between sessions. However, when resistance exercise is performed on subsequent days (~12 h apart), practitioners should prescribe post-exercise HWI to maximise isometric strength performance, while being cognisant of the effects that diurnal variation may have on muscular performance. [ABSTRACT FROM AUTHOR]