Relationship between exercise intensity and stress levels among U.S. medical students

BACKGROUND: Physical activity may protect the mental health of medical students, yet it is unknown which types and intensities of physical activity have the greatest potential to improve medical student well-being. OBJECTIVE: We characterize the relationship between exercise intensity and stress levels of U.S. medical students, thereby informing the design of future well-being interventions. DESIGN: Two cross-sectional validated surveys assessing stress and physical activity were administered one year apart at the David Geffen School of Medicine at UCLA. A total of 1,046 out of 1,392 medical students responded (75%). An ordered logistic regression was used to determine the association between stress and each level of exercise intensity (inactivity, moderate-activity, and health-enhancing physical activity [HEPA]). These exercise intensity groupings were compared to the CDC guidelines for aerobic exercise. RESULTS: While achieving either moderate-activity or HEPA is compliant with the CDC guidelines for aerobic exercise, the additional intensity of exercise required to achieve HEPA was associated with a 26% increase in the probability of being in the lowest stress quartile and a 22% decrease in the probability of being in the highest stress quartile. Medical student physical activity levels were on-par with the national average per the CDC exercise guidelines (65% vs. 58%), but medical student HEPA levels were significantly lower than the national average (27% vs. 64%; OR 0.21; 95% CI 0.12–0.37). CONCLUSIONS: There is a large disparity in rates of the highest intensity physical activity (HEPA) between medical students and the age-adjusted national average, which has previously been overlooked by the binary CDC exercise guidelines. The fact that HEPA levels are not optimized and more strongly associated with lower stress levels relative to less intense forms of exercise makes it a promising new target for future well-being interventions among medical trainees.