Differences in medial temporal network intrinsic connectivity after a single bout of exercise relate to fitness, memory, and affect.

Introduction: Chronic exercise has been linked to structural and functional changes in the hippocampus and surrounding areas. However, less is known about how a single session of exercise can induce immediate effects that may contribute to these long-term changes.

Objective/methods: Resting-state fMRI was used to investigate changes in brain networks 19 min after a 20-min bout of vigorous-intensity acute exercise. Fortyseven healthy young adults, aged 18-29, were recruited for the study.

Results: Whole-brain Independent Component Analysis revealed that only the medialtemporal network-including the bilateral hippocampus, amygdala, anterior temporal lobe, and parahippocampus-exhibited a reduction in intrinsic functional connectivity. All other brain networks remained unchanged. This reduction occurred specifically during the period following exercise and became less pronounced as more time elapsed since its completion. Additionally, the significance of this change was assessed using various correlates. The reduction was less pronounced in participants with higher levels of physical fitness, better performance in post-exercise memory tests, or a more positive post-exercise affective state compared to baseline.

Conclusions: A single bout of exercise leads to specific functional changes in the medial temporal network, which may be related to individual differences in the chronic changes resulting from repeated exercise bouts over time.