Memory loss is one of the most common complaints of older adults. Lifestyle interventions, including exercise, are increasingly popular to preserve brain health in older age. While there is ample empirical evidence to support the cognitive benefits of a physically active lifestyle, the neurophysiological mechanisms are difficult to determine conclusively in humans. Over months or years, it may not be possible to disentangle the independent effects of exercise from those attributed to factors such as social interactions and diet. However, if daily exercise accumulates to produce brain benefits over time, then it stands to reason that each session of exercise may produce effects from which these long-term adaptations occur.