How Often Students Exercise May Matter More Than How Hard, Study Finds

When it comes to lowering the risk of depression and anxiety, how often college students exercise may matter more than how hard they push themselves, according to a large Norwegian study. Students who exercised infrequently were more likely to develop clinically defined depression, anxiety or another common mental disorder over the following year, the researchers found. The study, led by Michael Grasdalsmoen of Western Norway University of Applied Sciences, was published in the open-access journal PLOS One.

Depression and anxiety are leading causes of disability among young adults worldwide, and the transition into higher education, with its academic pressure, financial concerns and disrupted routines, is an important window for prevention. The researchers tracked 10,460 full-time Norwegian students aged 18 to 35, who reported how often, how hard, and how long they exercised at the start of the study. One year later, the students completed a diagnostic assessment for common mental disorders.

Students with lower overall activity levels were more likely to meet clinical criteria for anxiety or depression at follow-up, and exercise frequency produced the most consistent association of all the measures examined. Among women, lower exercise intensity predicted anxiety and depression; among men, shorter weekly exercise duration was the stronger risk factor.

The probability of developing a common mental disorder declined as total weekly exercise increased, continuing up to about 10 hours a week, though the researchers said that does not mean students need to exercise that much to benefit. The findings also supported the World Health Organization's recommendation of at least 150 minutes of moderate-to-vigorous physical activity per week, and suggest that regular activity may be more practical than occasional intense workouts for students with demanding schedules.

Because the study was observational, it cannot prove that exercise itself prevents mental illness; other factors may affect both activity levels and mental health, and early symptoms of depression or anxiety can themselves make it harder to exercise. "Supporting students to be physically active may contribute to better mental health and should be recognized as an important part of a healthy learning environment," the authors wrote.