Neuromuscular Fatigue and Recovery after Heavy Resistance, Jump, and Sprint Training

Purpose Training methods that require maximal intensity efforts against light- and heavy-resistance are commonly used for athletic development. Typically these sessions are separated by at least 48 hours recovery on the assumption that such efforts elicit marked fatigue of the central nervous system (CNS), but this posit has not been well-studied. The aim of the study was to assess the aetiology and recovery of fatigue after heavy-resistance (strength), jump, and sprint training methods. Methods Ten male athletes completed three training sessions requiring maximal efforts that varied in their loading characteristics; i) heavy resistance exercise (10 × 5 back squats at 80% 1RM) (STR); ii) jumping exercise (10 × 5 jump squats) (JUMP); iii) maximal sprinting (15 × 30 m) (SPR). Pre-, post- and at 24, 48 and 72 h post- participants completed a battery of tests to measure neuromuscular function using electrical stimulation of the femoral nerve, and single- and paired-pulse magnetic stimulation of the motor cortex, with evoked responses recorded from the knee extensors. Fatigue was self-reported at each time point using a visual analogue scale. Results Each intervention elicited fatigue that resolved by 48 (JUMP) and 72 h (STR & SPR). Decrements in muscle function (reductions in the potentiated quadriceps twitch force) persisted for 48 h after all exercise. Reductions in voluntary activation were present for 24 h after JUMP and SPRINT, and 48 h after STR. No other differences in CNS function were observed as a consequence of training. Conclusion Strength, jump, and sprint training requiring repeated maximum efforts elicits fatigue that requires up to 72 h to fully resolve, but this fatigue is not primarily underpinned by decrements in CNS function. Address for correspondence: Glyn Howatson, Faculty of Health and Life Science, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK. Tel: +44 191 227 4863, Fax: +44 191 227 4713. Email: glyn.howatson@northumbria.ac.uk Support for the study was provided by the United Kingdom Strength & Conditioning Association research grants programme. The authors have no conflict of interest to declare. The results of the study do not constitute endorsement by ACSM. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 14 July 2018 © 2018 American College of Sports Medicine

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