Motor cortex plasticity is greater in endurance-trained cyclists following acute exercise

Abstract

Previous research using transcranial magnetic stimulation (TMS) has shown that plasticity within primary motor cortex (M1) is greater in people who undertake regular exercise, and a single session of aerobic exercise can increase M1 plasticity in untrained participants. This study aimed to examine the effect of an acute bout of exercise on M1 plasticity in endurance-trained (cyclists) and sedentary individuals. 14 endurance-trained cyclists (mean ± SD; 23 ± 3.8 years) and 14 sedentary individuals (22 ± 1.8 years) performed two experimental sessions. One session included an acute bout of high-intensity interval training (HIIT) exercise involving stationary cycling, while another session involved no-exercise (control). Following exercise (or control), I-wave periodicity repetitive TMS (iTMS) was used (1.5 ms interval, 180 pairs) to induce plasticity within M1. Motor evoked potentials (MEP) induced by single and paired-pulse TMS over M1 were recorded from a hand muscle at baseline, after HIIT (or control) exercise, and after iTMS. Corticospinal and intracortical excitability was not influenced by HIIT exercise in either group (all P > 0.05). There was an increase in MEP amplitude after iTMS, and this was greater after HIIT exercise (compared with control) for all subjects (P < 0.001). However, the magnitude of this response was larger in endurance cyclists compared with the sedentary group (P < 0.05). These findings indicate that M1 plasticity induced by iTMS was greater in endurance-trained cyclists following HIIT. Prior history of exercise training is, therefore, an important consideration for understanding factors that contribute to exercise-induced plasticity.