It’s conventional wisdom that exercise can improve mental health, and possibly prevent depression. But how much ido you need to do to see a change? New research, published in the Lancet Psychiatry, says that just two hours of any form of exercise each week is enough to see changes.
“One of the nice things is the accessibility of this,” says study co-author Adam Chekroud, an assistant professor of psychiatry at Yale University. “It seems like some of the benefits are pretty in reach for most people.”
The study's authors said in the abstract, "Exercise is known to be associated with reduced risk of all-cause mortality, cardiovascular disease, stroke, and diabetes, but its association with mental health remains unclear. We aimed to examine the association between exercise and mental health burden in a large sample, and to better understand the influence of exercise type, frequency, duration, and intensity."
In the huge sampled study, they analyzed data from 1,237,194 people aged 18 years or older in the USA from the 2011, 2013, and 2015 Centers for Disease Control and Prevention Behavioral Risk Factors Surveillance System survey. They compared the number of days of bad self-reported mental health between individuals who exercised and those who did not, using "an exact non-parametric matching procedure" to balance the two groups in terms of age, race, gender, marital status, income, education level, body-mass index category, self-reported physical health, and previous diagnosis of depression. They then examined the effects of exercise type, duration, frequency, and intensity using regression methods adjusted for potential confounders, and did multiple sensitivity analyses.
There results suggested by the large US sample, are "that physical exercise was significantly and meaningfully associated with self-reported mental health burden in the past month. However more exercise was not always better." Differences as a function of exercise were large relative to other demographic variables such as education and income. "Specific types, durations, and frequencies of exercise might be more effective clinical targets than others for reducing mental health burden, and merit interventional study," they concluded.
Chekroud says people who don’t exercise miss out on the mood-boosting effects of fitness, which he says may actually change the way the brain functions.
“There’s a lot of literature suggesting that people who are depressed and taking antidepressants who also exercise generally do better than people who just take antidepressants,” he says. “I think there’s for sure something going on neurobiologically in people who have depression that’s being helped by exercise.”