High-Volume Light-Load Strength Training, but Not Low-Volume Heavy-Load Strength Training Increases Corticospinal Excitability

Purpose: To determine whether corticospinal excitability (CSE) and inhibition aredifferentially modulated following high-volume light-load strength training compared to low-volume heavy-load strength training. We hypothesised high-volume light-load strengthtraining would increase CSE and low-volume heavy-load strength training would reduceintracortical inhibition. Methods: Transcranial magnetic stimulation (TMS) was used to assess CSE, short-intervalintracortical inhibition (SICI), and silent period duration (SP) following high-volume light-loadstrength training (n = 9), low-volume heavy-load strength training (n = 8) compared to acontrol group (n = 10). Twenty-seven participants completed either (1) low-volume heavy-loadstrength training (80% one-repetition maximum [1RM]); (2) high-volume light-load strengthtraining (20% 1RM) or (3) a control condition. CSE, SICI and SP were measured using TMS atbaseline and four time-points over a 60 min post-exercise period. Results: CSE increased rapidly (within 5 min post-exercise) for high-volume light-loadstrength training and remained elevated for 60 min compared to low-volume heavy-loadstrength training and control groups. There were no differences following any training forreduced SICI or SP. Conclusion: These results suggest that high-volume light-load strength training increases theexcitability of corticospinal neurons and this increase is likely to be the predominantmechanism for increasing CSE for up to 60 min post training. It may be possible that agreater number of ST sessions are required to observe any differences in the excitability ofthe intrinsic inhibitory motor-network following high-volume light-load strength training andlow-volume heavy-load strength training