Hand, B.J.Opie, G.M.Sidhu, S.K.Semmler, J.G.2022-09-292022-09-292022Journal of Applied Physiology, 2022; 133(4):932-9448750-75871522-1601https://hdl.handle.net/2440/136511First published September 8, 2022Previous 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.en© 2022, Journal of Applied PhysiologyTranscranial magnetic stimulation; exercise; physical activity; plasticityJournal article10.1152/japplphysiol.00213.20222022-09-29621195Hand, B.J. [0000-0002-9778-343X]Opie, G.M. [0000-0001-7771-7569]Sidhu, S.K. [0000-0002-4797-8298]Semmler, J.G. [0000-0003-0260-8047]