Neuromuscular adjustments of the quadriceps muscle after repeated cycling sprints.

Abstract

PurposeThis study investigated the supraspinal processes of fatigue of the quadriceps muscle in response to repeated cycling sprints.MethodsTwelve active individuals performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 × 6-s sprints (recovery = 30 s). Transcranial magnetic and electrical femoral nerve stimulations during brief (5-s) and sustained (30-s) isometric contractions of the knee extensors were performed before and 3 min post-exercise.ResultsMaximal strength of the knee extensors decreased during brief and sustained contractions (~11% and 9%, respectively; P0.05). While cortical voluntary activation declined (P 40%) reduced (PConclusionThe capacity of the motor cortex to optimally drive the knee extensors following a repeated-sprint test was shown in sustained, but not brief, maximal isometric contractions. Additionally, peripheral factors were largely involved in the exercise-induced impairment in neuromuscular function, while corticospinal excitability was well-preserved.