The effects of acute high-intensity aerobic exercise on motor cortical plasticity and motor learning

Background: Motor learning is mediated by plasticity of neural circuits involved in movement. As such, there is great interest in the development of strategies that maximize brain plasticity to promote motor learning. Aerobic exercise has emerged as an intervention with robust effects on the nervous system, including interactions with mechanisms of neuroplasticity and memory. Yet, the effects of acute aerobic exercise on plasticity and learning in the motor system are not well understood. Methods: The overall objective of this thesis was to examine the effects of a single bout of high-intensity aerobic exercise on motor cortical (M1) plasticity and motor learning for an upper limb muscle in young healthy individuals. The first three research chapters describe experiments evaluating the effects of acute high-intensity cycling on: M1 plasticity (Chapter 2), continuous motor sequence learning (Chapter 2), activity in cerebello-motor circuits (Chapter 3) and discrete motor sequence learning (Chapter 4). In Chapter 5, a study exploring relationships of genetic and epigenetic variation with acute aerobic exercise effects on M1 plasticity and motor learning is described. Summary of findings: In Chapter 2, M1 plasticity induced by paired associative stimulation was facilitated when preceded by exercise, compared to a period of rest. Further, continuous motor sequence learning was enhanced when exercise was performed prior to task practice. Transcranial magnetic stimulation assessments utilized in Chapter 3 suggested that modulation of activity in cerebello-motor circuits may contribute to exercise-induced facilitation of M1 plasticity. In Chapter 4, exercise prior to discrete motor sequence task practice enhanced the rate of improvement in task performance at a 24-hour retention test, suggesting an effect of aerobic exercise on motor memory retrieval. Finally, in Chapter 5 genetic variants and DNA methylation patterns impacting brain-derived neurotrophic factor and dopamine signaling pathways were associated with inter-individual variability in exercise effects on M1 plasticity and motor learning. Conclusions: This dissertation contributes new knowledge towards understanding the effects of acute high-intensity aerobic exercise on plasticity and learning in the motor system. The findings have implications for development of strategies to prime neuroplasticity and motor learning with acute aerobic exercise in sport or rehabilitation settings.Medicine, Faculty ofGraduat