The Effect of Self-Paced Exercise Intensity and Cardiorespiratory Fitness on Frontal Grey Matter Volume in Cognitively Normal Older Adults: A Randomised Controlled Trial

Objective: Exercise has been found to be important in maintaining neurocognitive health. However, the effect of exercise intensity level remains relatively underexplored. Thus, to test the hypothesis that self-paced high-intensity exercise and cardiorespiratory fitness (peak aerobic capacity; VO) increase grey matter (GM) volume, we examined the effect of a 6-month exercise intervention on frontal lobe GM regions that support the executive functions in older adults.

Methods: Ninety-eight cognitively normal participants (age = 69.06 ± 5.2 years; = 54 female) were randomised into either a self-paced high- or moderate-intensity cycle-based exercise intervention group, or a no-intervention control group. Participants underwent magnetic resonance imaging and fitness assessment pre-intervention, immediately post-intervention, and 12-months post-intervention.

Results: The intervention was found to increase fitness in the exercise groups, as compared with the control group ( = 9.88, = <0.001). Changes in pre-to-post-intervention fitness were associated with increased volume in the right frontal lobe ( = 0.29, = 0.036, = 0.27), right supplementary motor area ( = 0.30, = 0.031, = 0.29), and both right ( = 0.32, = 0.034, = 0.30) and left gyrus rectus ( = 0.30, = 0.037, = 0.29) for intervention, but not control participants. No differences in volume were observed across groups.

Conclusions: At an aggregate level, six months of self-paced high- or moderate-intensity exercise did not increase frontal GM volume. However, experimentally-induced changes in individual cardiorespiratory fitness was positively associated with frontal GM volume in our sample of older adults. These results provide evidence of individual variability in exercise-induced fitness on brain structure.