Physical activity may buffer against depression and promote resilience after major life stressors

As many individuals experience potentially traumatic or stressful life events, understanding factors that are likely to promote resilience is imperative. Given the demonstrated efficacy of exercise for depression treatment, we examined if exercise buffers against the risk of developing psychiatric symptoms following life stressors. 1405 participants (61% female) from a longitudinal panel cohort experienced disability onset (43%), bereavement (26%), heart attack (20%), divorce (11%), and job loss (3%). They reported time spent exercising and depressive symptoms (Center for Epidemiologic Studies Depression scale) across three time points collected in two-year intervals: T0 (pre-stressor), T1 (acutely post-stressor), and T2 (post-stressor). Participants were classified in previously identified heterogeneous depression trajectories pre- to post-life stressor: resilient (69%), emerging (11.5%), chronic (10%), and improving (9.5%). Multinomial logistic regression found that more T0 exercise predicted likelihood of classification in resilient versus other groups (all p<.02). Controlling for covariates, only the higher likelihood of classification in resilient versus improving remained (p=.03). Follow-up repeated measures general linear model (GLM) assessed whether trajectory was associated with exercise at each time, controlling for covariates. GLM indicated significant within-subjects effects for time (p=.016, partial η²=.003) and time*trajectory (p=.020, partial η²=.005) on exercise and significant between-subjects effects of trajectory (p<.001, partial η²=.016) and all covariates. The resilient group showed consistent high exercise levels. The improving group had consistent moderate exercise. The emerging and chronic groups were associated with lower exercise post-stressor. Pre-stressor exercise may buffer against depression and ongoing exercise may be associated with lower depression levels following a major life stressor.