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We examined the sensitivity and time‐course of recovery of neuromuscular and perceptual player monitoring measures to U‐18 English Premier League academy football match play. Eighteen players performed maximal posterior chain, hip adductor and abductor isometric strength tests, countermovement jumps (CMJ) and provided self‐report wellbeing scores around eight competitive league home games: 1 day before (MD‐1), pre‐match (MD‐PRE), post‐match (MD‐POST) and two (MD+2) and three (MD+3) days post‐match. A permutational multivariate analysis of variance and post hoc univariate analyses of variance were used to examine match‐induced responses to monitoring variables. Between MD‐1 and MD‐POST, we observed small to moderate reductions to the adductor and abductor peak force and maximal impulse and IPCS peak force; small reductions to CMJ jump height (JH) (flight time), eccentric peak force and eccentric deceleration rate of force development and moderate to large reductions to perceived fatigue, muscle soreness and mood. No match‐induced changes were observed for CMJ flight time: contraction time or eccentric duration. Posterior chain, abductor, CMJ and self‐report measures normalised by MD+3 but adductor peak force remained compromised at MD+3 (ES = small). Posterior chain, adductor and abductor peak isometric force and maximal impulse; CMJ JH, eccentric peak force and eccentric deceleration rate of force development and perceived fatigue, muscle soreness and mood are sensitive to match‐induced fatigue. Since adductor peak force remained compromised at MD+3, it is apparent that players might not achieve complete neuromuscular recovery within 3 days of match play, and that the adductor muscle group might be particularly vulnerable to match‐induced fatigue. Highlights: U‐18 English Premier League (EPL) academy football match play induced acute reductions to countermovement jump (jump height [flight time], eccentric peak force and eccentric deceleration rate of force development); isometric strength (abductor, adductor and posterior chain peak force and abductor and adductor maximal impulse) and athlete self‐report (perceived fatigue, muscle soreness and mood) measures.Match‐induced changes to countermovement jump, abductor, posterior chain and self‐report measures typically normalised between MD+2 and MD+3 but adductor peak force remained compromised at MD+3.No meaningful match‐induced changes were observed to widely used countermovement jump movement strategy measures (i.e., flight time: contraction time ratio or eccentric duration).U‐18 EPL academy football players might not achieve complete neuromuscular recovery by MD+3. The adductor muscle group might be particularly susceptible to match‐induced fatigue. [ABSTRACT FROM AUTHOR]

The aim was to determine the validity of an open-source algorithm for measuring jump height and frequency in ballet using a wearable accelerometer. Nine professional ballet dancers completed a routine ballet class whilst wearing an accelerometer positioned at the waist. Two investigators independently conducted time-motion analysis to identify time-points at which jumps occurred. Accelerometer data were cross-referenced with time-motion data to determine classification accuracy. To determine the validity of the measurement of jump height, five participants completed nine jetés, nine sautés and three double tour en l'air from a force plate. The jump height predicted by the accelerometer algorithm was compared to the force plate jump height to determine agreement. Across 1440 jumps observed in time-motion analysis, 1371 true positives, 34 false positives and 69 false negatives were identified by the algorithm, resulting in a sensitivity of 0.98, a precision of 0.95 and a miss rate of 0.05. For all jump types, mean absolute error was 2.6 cm and the repeated measures correlation coefficient was 0.97. Bias was 1.2 cm and 95% limits of agreement were −4.9 to 7.2 cm. The algorithm may be used to manage jump load, implement periodization strategies, or plan return-to-jump pathways for rehabilitating athletes. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to describe the relationships between dance exposure, dancer characteristics, and injury risk across five seasons in a professional ballet company. Methods: Dance exposure time and clinician-reported time-loss and medical attention injury data were prospectively collected from 118 professional dancers of The Royal Ballet between 2015/2016 and 2019/2020. Cox proportional hazards and shared frailty models were fitted to overuse and traumatic injuries; individualized robust Zscores for 7- and 28-d accumulated exposure, and week-to-week change in exposure, age, sex, company rank, and injury historywere included as time-varying covariates. Results: Across 381,710 h of exposure, 1332 medical attention and 427 time-loss injuries were observed. Positive relationships were observed between week-to-week change in exposure and overuse time-loss (+1 Z-score hazard ratio (HR), 1.27; 95% confidence interval (CI), 1.06-1.53) and medical attention injury risk (+1 Z-score HR, 1.17; 95% CI, 1.06-1.28). A negative relationship was observed between 7-d accumulated exposure and overuse medical attention injury risk (+1 Z-score HR, 0.74; 95% CI, 0.66-0.84). Overuse time-loss injury risk was greater in soloists compared with the corps de ballet (HR, 1.47; 95% CI, 1.01-2.15) and in dancers with a higher previous injury rate (+1 injury per 1000 h HR, 1.06; 95% CI, 1.02-1.10). Only age was associated with traumatic time-loss (+1-yr HR, 1.05; 95% CI, 1.01-1.09) or medical attention injury risk (+1-yr HR, 1.04; 95% CI, 1.01-1.07). Conclusions: Professional ballet companies should implement training principles such as periodization and progression, particularly in the case of senior-ranking dancers, older dancers, and dancers with high rates of previous injury. These findings provide a basis for future prospective investigations into specific causal injury pathways. [ABSTRACT FROM AUTHOR]