One of the largest studies to date on exercise and psychological distress shows that the optimal amount of physical activity for improved mental health may be from 2.5 to 7.5 hours of activity per week.

However, the cross-sectional observational study also showed that individuals who exercised more than 7.5 hours per week had diminished mental health.

Although the study has clear limitations, it raises interesting questions about the optimal amount of exercise needed for good mental health and the effect of excessive exercise on symptoms of depression and anxiety, researchers note.

“We know that 150 minutes per week of exercise is needed for improved cardiovascular health and reduced risk for diabetes, and greater amounts are needed for weight management. Yet there’s no clear data about the amount of exercise needed for mental health,” lead researcher Carol Ewing Garber, PhD, associate professor of biobehavioral science at Teachers College, Columbia University, in New York City, told Medscape Medical News. “There are also no data in large studies that show there can be detrimental effects of too much exercise,” Dr. Garber added.

However, she said that although high levels of exercise might lead to poorer mental health outcomes, it is hard to know whether the physical activity is actually causative.

“People who have a propensity for poor mental health may also be attracted to extreme levels of exercise,” Dr. Garber said.

The study was published online September 7 in Preventive Medicine. The study included self-reported data on physical activity and mental health symptoms from 7674 adults from the 2007 US Health Information National Trends Survey (HINTS).

Mental health was assessed using the 6-item HINTS questionnaire, which poses questions about psychological distress, depression, and anxiety over the past 30 days. Participants were also asked to report the frequency and duration of their participation in physical activity that caused an increase in breathing.

The researchers also looked at the association between mental health and other variables, such as age, employment, marital status, education, income, physical health, and race and ethnicity.

The investigators found that individuals who engaged in 2.5 to 7.5 hours of exercise per week were 1.39 times more likely to have better mental health, compared with those who exercised for less or greater amounts of time (P = .006).

Older age, college education, income over $50,000 per year, and better physical health were also associated with improved mental health.

Dr. Garber acknowledged that the findings of the study could be influenced by recall bias. “Still, the study is very supportive of the benefits of exercise for mental health,” she said.

Findings “Make Sense”

Commenting for Medscape Medical News, Emanuel Maidenberg, PhD, director of the University of California, Los Angeles (UCLA) Cognitive Behavior Therapy Clinic and associate clinical professor at the Semel Institute at UCLA, said, “The study’s findings do make sense.”

“If someone is exercising 10 to 15 hours a week, it’s likely to be at the expense of other activities that could bring his or her life into balance,” Dr. Maidenberg told Medscape Medical News. Dr. Garber noted that frequent exercise of 8 hours or more per week may come at the expense of other things important for mental health, such as social interaction, family ties, and relaxation time. “There are good data that rigorous physical activity for 30 minutes a day is fairly effective treatment for depression,” Dr. Maidenberg said.

Yet, when a person feels that frequent bouts of exercise are a need, rather than a choice, then physical activity has the potential to be compulsive, he noted.

When exercise is a compulsion, it is likely to be seen as part of a constellation of symptoms in a mental illness, such as anorexia or obsessive compulsive disorder, Dr. Maidenberg said. “If a patient says: ‘I need to work out for 2 hours a day, and if I don’t, I feel anxious,’ that’s an indication that their activity is driven by anxiety and not choice,” he said.

Dr. Garber and Dr. Maidenberg have disclosed no relevant financial relationships.

Prev Med. Published online September 7, 2012. Abstract Medscape Medical News © 2012 WebMD, LLC Send comments and news tips to news@medscape.net.

Cite this article: Optimal Amount of Exercise for Mental Health Revealed. Medscape. Oct 25, 2012. http://www.medscape.com/viewarticle/773331_print