Physical Activity Moderates Effects of Stressor-Induced Rumination on Cortisol Reactivity
Published Web Locationhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3167008/
OBJECTIVE Physically active individuals have lower rates of morbidity and mortality, and recent evidence indicates that physical activity may be particularly beneficial to those experiencing chronic stress. The tendency to ruminate increases and prolongs physiological stress responses, including hypothalamic-pituitary adrenal (HPA) axis responses as indexed by cortisol reactivity to stressful experiences. We examined the association between ruminating in response to a laboratory stressor task and HPA axis reactivity and recovery, and whether a physically active lifestyle moderates the associations between rumination and cortisol output trajectories. METHODS Forty-six post-menopausal women underwent the Trier Social Stress Test while salivary cortisol was repeatedly measured. Twenty-five minutes after the end of the stressor, participants reported level of rumination in response to the stress. RESULTS Findings indicate that physical activity moderated the initial rate (B = −.10, SE = .04, p < .05) and curvature (B = −.03, SE = .01, p = .06) of the relationship between rumination and log-transformed cortisol trajectory. Among sedentary participants, those who responded to the stressor with higher levels of rumination had a more rapid initial increase in cortisol (0.26 vs 0.21, p < .001), a later peak (56 vs. 39 minutes), and a delayed recovery (curvature −0.07 vs. −0.08, p < .001) compared to those with lower levels of rumination. In active participants, cortisol trajectories were equivalent, regardless of level of rumination. CONCLUSIONS In sum, individuals who maintain a physically active lifestyle may be protected against the effects of rumination on HPA axis reactivity to and recovery from acute stress.