Factors that influence the neurobiological effects of exercise likely extend beyond age and intensity in people with major depression.

We recently conducted a comprehensive systematic review of neurobiological effects of exercise on major depressive disorder. A subsequent letter suggested that we should consider children and adolescent and raised the importance of how intensity may mediate neurobiological response in people with depression. Here, we discuss these comments regarding our review, in addition to proposing that other factors, such type, duration, frequency, and adherence, may also importantly influence neurobiological response, based on recent meta-analyses demonstrating these other aspects of physical activity also moderate dropout rates and effect sizes from exercise upon depression.