Motor cortex plasticity and visuomotor skill learning in upper and lower limbs of endurance-trained cyclists.

Abstract

Studies with transcranial magnetic stimulation (TMS) show that both acute and long-term exercise can influence TMS-induced plasticity within primary motor cortex (M1). However, it remains unclear how regular exercise influences skill training-induced M1 plasticity and motor skill acquisition. This study aimed to investigate whether skill training-induced plasticity and motor skill learning is modified in endurance-trained cyclists. In 16 endurance-trained cyclists (24.4 yrs; 4 female) and 17 sedentary individuals (23.9 yrs; 4 female), TMS was applied in 2 separate sessions: one targeting a hand muscle not directly involved in habitual exercise and one targeting a leg muscle that was regularly trained. Single- and paired-pulse TMS was used to assess M1 and intracortical excitability in both groups before and after learning a sequential visuomotor isometric task performed with the upper (pinch task) and lower (ankle dorsiflexion) limb. Endurance-trained cyclists displayed greater movement times (slower movement) compared with the sedentary group for both upper and lower limbs (all P < 0.05), but there was no difference in visuomotor skill acquisition between groups (P > 0.05). Furthermore, endurance-trained cyclists demonstrated a greater increase in M1 excitability and reduced modulation of intracortical facilitation in resting muscles of upper and lower limbs after visuomotor skill learning (all P < 0.005). Under the present experimental conditions, these results indicate that a history of regular cycling exercise heightens skill training-induced M1 plasticity in upper and lower limb muscles, but it does not facilitate visuomotor skill acquisition.