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Purpose: This study aimed to explore the influence of differences in relative skeletal maturity on performance test outcomes in elite youth soccer players from the Middle East. Methods: We integrated skeletal age and performance assessments using mixed-longitudinal data available for 199 outfield players (chronological age range, 11.7 to 17.8 yr) enrolled as academy student-athletes (annual screening range, 1 to 5 visits). Skeletal age was determined as per the Tanner–Whitehouse II protocol. Relative maturity was calculated as the difference (∆) between Tanner–Whitehouse II skeletal age minus chronological age. Performance test outcomes of interest were 10-m sprinting, 40-m sprinting, countermovement jump height, and maximal aerobic speed. Separate random-effects generalized additive models quantified differences in performance test outcomes by relative skeletal maturity. Estimated differences were deemed practically relevant based on the location of the confidence interval (95% CI) against minimal detectable change values for each performance test outcome. Results: For 40-m sprinting, differences of +0.51 s (95% CI, +0.35 to +0.67 s) and +0.62 s (95% CI, +0.45 to +0.78 s) were practically relevant for relative maturity status of ∆ = −1.5 yr versus ∆ = +0.5 and ∆ = +1 yr, respectively. For countermovement jump height, a difference of −8 cm (95% CI, −10 to −5 cm) was practically relevant for ∆ = −1.5 yr versus ∆ = +1 yr relative maturity status comparison. Effects for 10-m sprinting and maximal aerobic speed were unclear. Conclusions: Integration of skeletal age and performance assessments indicated that conventional maturity status classification criteria were inconsistent to inform player development processes in our sample. Between-player differences in test performance may depend on a substantial delay in skeletal maturation (∆ ≤ −1.5 yr) and the performance outcome measure. [ABSTRACT FROM AUTHOR]

Research is presented that compares the effects of conventional, complex, and contrast protocols on lower-body power in 18 men, noting that static and dynamic contractions were manipulated and used as confounding variables. The protocols were based on repetitions or combination of countermovement jumps (CMJs), five-second static back squats, and rest periods. The finding is that a conventional protocol of three sets of four CMJs with a two-minute interval produced greater peak power output.

Objectives: Examine the influence of test modality, season stage, match load and physical qualities on the interpretation of neuromuscular function (NF) post Australian Rules Football (ARF) matches., Design: Repeated measures design., Methods: Thirty-two elite ARF players' NF was assessed 72h following competitive matches (7±2) via the counter movement jump (CMJ) and isometric mid-thigh pull (IMTP). Influence of season stage, external load parameters (GPS; 10Hz) and moderating influences of lower body strength (LBS), lower body power (LBP) and intermittent exercise capacity upon NF recovery were assessed using linear mixed effects models., Results: Moderate negative seasonal trends were evident for both rate of force development (RFD) 0-100ms (d=-0.86, 95%, CI: ±0.57) and 0-200ms (d=-0.76, CI: ±0.64). Significant but trivial effects of match load were observed between one standardised unit increase in high speed running (HSR) versus CMJ: Force at zero velocity (d=0.12, CI: ±0.12), and sum of high intensity accelerations and CMJ: Eccentric deceleration RFD (d=-0.18, CI: ±0.14). Accounting for baseline LBS better explained (weight of evidence: W=87%) seasonal trends observed in IMTP: peak force, with lower LBS showing greater capacity for improvement. Positive moderating influences were observed with baseline LBS and LBP (W=91 & 75%) on CMJ: eccentric mean power responses to HSR, and CMJ: jump height responses to very-HSR, respectively., Conclusions: Interpretation of athlete NF responses is complicated by the inconsistent and interacting influence of contextual factors (assessment modality, stage of season, load), in-particular higher baseline LBS and LBP may improve acute load related responses of NF., (Crown Copyright © 2021. Published by Elsevier Ltd. All rights reserved.)