INTRODUCTION: We profiled the aetiology and recovery time-course of neuromuscular function in response to a mixed-content, standard training week in professional academy soccer players. We concurrently examined physical performance, cognitive function, and perceptual measures of mood and wellness states to identify a range of simple tests applied practitioners could use in the field as surrogate measures of neuromuscular function. METHODS: Sixteen professional academy soccer players completed a strenuous training day (pitch and strength sessions), followed by a moderate training day two days later. Pre-, post-, and at 24, 48, and 72 h post-strenuous day, participants completed a range of neuromuscular, physical, perceptual, mood, and cognitive function tests. Maximal voluntary contraction force (MVC) and twitch responses to electrical stimulation (femoral nerve) during isometric knee-extensor contractions and at rest were measured to assess central nervous system (voluntary activation, VA) and muscle contractile (potentiated twitch force, Qtw,pot) function. Fatigue and perceptions of wellness and mood states were assessed via visual analogue and likert scales. Cognitive function was assessed via the Stroop task. Countermovement jump, reactive strength index, and bilateral isometric adductor contraction (adductor squeeze) were assessed to profile the recovery of physical function. RESULTS: Strenuous training elicited decrements in MVC force post-session (-11%, P = 0.001) that remained unresolved at 72 h (-6%, P = 0.03). Voluntary activation (motor point stimulation) was reduced immediately post-training only (-4%, P = 0.03). No change in muscle contractile function (Qtw,pot) was observed post-training, though was reduced at 24 h (-13%, P = 0.01), and had not fully recovered 72 h after (-9%, P = 0.03). Perceptions of fatigue, muscle soreness, training difficulty and sleepiness increased post-training, and had recovered by 24 h (sleepiness) and 48 h (fatigue, muscle soreness, training difficulty). Perceived levels of energy and readiness to train were decreased at post-training, before recovering at 24 h (energy levels) and 48 h (readiness to train). Countermovement jump performance, though unchanged immediately post-training, declined at 24 h and took 48 h to recover. RSI decrements persisted at 48 h, before recovering by 72 h. No changes were evident in adductor squeeze measures, mood scores or cognitive function. CONCLUSION: Elite youth soccer training elicits substantial decrements in neuromuscular function, which are still present 72 h post-strenuous exercise. Though central processes contribute to post-exercise neuromuscular alterations, the magnitude and prolonged presence of impairments in contractile function indicates it is the restitution of muscular function (peripheral mechanisms) that explains recovery from strenuous training in academy soccer players. Collectively the findings could inform training, preparation and recovery activities to maximise longer-term player development and athletic progression at this critical point in their maturation.
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