When the body perceives a stressor, the hypothalamic-pituitary-adrenal (HPA) axis is activated leading to synthesis and release of cortisol from the adrenal cortex. Exercise is a physical stressor that increases cortisol levels in the body. Studies have considered exercise as a self-regulatory strategy to adapt to stressful events. Performance athletes have previously been shown to have higher baseline cortisol levels. The effects of exercise on cortisol levels in the general population is less clear. The aim of this study was to examine the relationship between exercise and physiological responses to stress in college students.
Stress was induced in the undergraduates (with the approval of the Union College Human Subjects in Research Committee) using the Trier Social Stress Test (TSST). Saliva samples were taken four times during the study; pre TSST, immediately post TSST, and 5 min and 30 min after the TSST. Salivary cortisol was measured using an enzyme-linked immunosorbent assay. In addition to physiological measures, participants completed the brief mood introspection scale, the revised undergraduate hassles scale, and a self-reported exercise survey describing the frequency and intensity of their exercise habits. Students also completed a perceived functional ability questionnaire (PFA) rating their ability to jog, walk or run over a given distance which reflects participants’ physical activity and fitness.
Participants were divided into two groups based on the mean PFA score (7.5). The results showed that participants with a PFA score above the mean had lower baseline cortisol on average, compared to participants with a PFA score below the mean. The results from this study suggest that physically active participants have lower baseline cortisol levels when compared to their peers who are less physically active. Together these data indicate the need for specific stress-reduction programs for college students that include physical activity as one aspect of the intervention.