Neuromuscular fatigue in English Premier League academy football players: Within- and cross-season responses

Objectives: To examine the within- and cross-season neuromuscular fatigue responses in English Premier League U-18 academy football players.

Design: Twenty-five players from the same team completed weekly countermovement jump and isometric adductor and posterior chain strength tests for a full competitive season.

Methods: Global positioning system measures of training and match total, high-metabolic load and sprint distance were recorded daily and converted into exponentially weighted moving average seven- and twenty-eight-day values.

Results: TD₂₈ (p < .001), HML₂₈ (p < .001), and SD₂₈ (p = .002) shared negative relationships with countermovement jump height, but there was no main cross-season effect (p = .137). TD₂₈ (p = .016) and HML₂₈ (p = .012) positively related to isometric posterior chain strength but there was no effect of SD₂₈ (p = .653), SD₇ (p = .549), TD₇ (p = .080) or HML₇ (p = .104). Cross season, isometric posterior chain strength followed a curvilinear response whereby performance increased across the beginning of the season and decreased towards the end of the season (p = .003). There was no effect of training load or time on isometric adductor strength performance (p > .094).

Conclusions: Neuromuscular status, signalled by countermovement jump height changes fluctuates across the season in response to sustained changes in training and match load, but there is no evidence of a main cross-season linear effect. Total training and match volume exert moderating effects on the internal training load dose, and in-turn, important moderating effects on neuromuscular fatigue, particularly when composed of high volumes of high-intensity and sprint distances. The posterior chain might be particularly susceptible to fatigue towards the end of the season.