Experimentally investigating the joint effects of physical activity and sedentary behavior on depression and anxiety: A randomized controlled trial

Abstract

Objective: To experimentally examine whether increasing sedentary behavior, among a young adult active population, for one week is still associated with increased depression and anxiety symptomology even when allowing for a moderate engagement in physical activity (PA).

Methods: Participants were confirmed as active via self-report and accelerometry during baseline and randomly assigned to one of three experimental groups. The No Exercise Group (n = 19) was instructed to reduce steps to less than 5000/day and were not allowed to exercise for one-week; the Reduced MVPA (moderate-to-vigorous PA) Group (n = 18) was instructed to reduce steps to less than 5000/day but exercised for 50% of their previously reported vigorous PA for one-week; and the Control Group (n = 20) maintained normal activity for one-week. PA, depression, and anxiety levels were assessed at baseline, post-intervention, and after one week of resumed normal activity for the intervention groups.

Results: The experiment was successful in altering physical activity levels among the intervention groups and maintaining activity habits in the control group (F_Interaction = 16.053, P < 0.001, η²_p = 0.391). Anxiety and depression symptomology remained constant across the two time periods in the control group. For both intervention groups (No Exercise Group and Reduced MVPA Group), depression statistically significantly increased during the inactive week and then resumed back to baseline levels after a week of resumed activity. However, there were no differential trends in anxiety (F_Interaction = 0.073, P = 0.897, η²_p = 0.002) or depression (F_Interaction = 0.276, P = 0.760, η²_p = 0.008) among these two intervention groups.

Conclusion: We provide experimental evidence that reducing habitual physical activity causes an increase in depression symptomology among young active adults. We did not, however, observe a joint effect of sedentary behavior and exercise on changes in anxiety and depression. At this point, it is still uncertain as to whether reduced MVPA or increased sedentary behavior were driving the observed changes in psychological function. Future research may help determine if these negative effects are from increased sedentary behavior or a reduction in MVPA.

Keywords: Accelerometry; Exercise; Exercise cessation; Exercise withdrawal; Interaction; Intervention; Mental health.