Antidepressive effects of physical exercise interventions Review of potential mechanisms of action

Background Due to an insufficient healthcare situation and an unsatisfactory efficacy of the standard treatment in major depressive disorders, research on additional low-threshold treatment options is necessary. Meta-analyses have shown an anti-depressive effect of physical exercise interventions; however, in order to develop the best possible treatment programs, it is important to understand the underlying mechanisms. Objective This review article provides an overview on the current state of research on probable biological and psychological mechanisms of physical exercise for major depressive disorders. Material and methods On the basis of the current literature, the best studied anti-depressive mechanisms of physical exercise are described and discussed. Studies involving patients with major depressive disorders are presented as well as studies with healthy participants and research on animal models. Results The following probable anti-depressive mechanisms are described: neuroplasticity, neuroendocrinological processes, anti-inflammatory processes and adaptation to oxidative stress as well as effects on self-efficacy and self-esteem. Comparative studies between, e.g. different types of sport or levels of intensity are mostly lacking. Conclusion Based on the findings from basic research, several mechanisms of physical exercise can be derived that are probably involved in anti-depressive effects; however, the state of research in clinical studies including patient samples is still insufficient. Thus, there is a substantial need for further research in this field.