Acute neuromechanical modifications and 24-h recovery in quadriceps muscle after maximal stretch-shortening cycle...

In the present study we investigated the acute and the delayed changes in corticospinal excitability and in the neuromechanical properties of the quadriceps muscle after maximal intensity stretch-shortening cycle exercise. Ten young males performed 150 jumps to provoke fatigue and muscle damage. Voluntary force, various electrically evoked force variables, and corticospinal excitability were measured at baseline, immediately (IP) and at 24 h post-exercise. Voluntary force, single twitch force, and low frequency force decreased at IP (p < 0.05) but recovered at 24 h, although mild soreness developed in the quadriceps. High frequency force, voluntary activation, and corticospinal excitability remained unchanged. However, vastus lateralis myoelectric activity increased from baseline to IP (p < 0.05). The jumps selectively induced low frequency peripheral fatigue, and central mechanisms did not mediate the acute loss of voluntary force. Because soreness developed at 24 h post-exercise, all force variables recovered, and vastus lateralis electric activity increased, we argue that a dual process of muscle damage, and early neural adaptation as a compensation mechanism took place after the maximal stretch-shortening cycle exercise.