Women who get at least three and a half hours of leisure-time activity each week are less likely to be depressed, research from Australia shows.

In contrast, the amount of exercise women got on the job, doing housework, or going from place to place did not affect their mood, the researchers found, but some social factors did.

Women who were discouraged from exercising were more likely to be depressed, but those who exercised with a family member were happier.

The findings support the idea that "improvements in mental health following exercise are at least partly related to the mutual support and social relationships that are provided when participating in physical activity," Dr Megan Teychenne and colleagues from Deakin University in Burwood, Victoria write.

Physical activity is known to help reduce the risk of depression, but it isn't clear how much exercise is needed for this to occur, how intense exercise should be, or in what context it should happen, Teychenne and her team report in the International Journal of Behavioral Nutrition and Physical Activity.

To investigate, they surveyed 1501 women 18 to 65 years old. Thirty per cent had symptoms of depression.

As mentioned, women who reported at least three and a half hours a week of leisure-time physical activity were less likely to be depressed, the researchers found, and vigorous activity seemed to have a more powerful effect.

Study participants who reported being discouraged from exercising were more likely to be depressed - and the more frequently someone discouraged them, the greater their depression risk, the researchers found.

But women who belonged to sporting or recreational clubs, had a neighbourhood walking partner, or exercised with a family member were less likely to have symptoms of depression.

Having a dog to walk, working out with a friend or colleague, or exercising alone most of the time did not independently influence depression risk, however.

"It may be that the support for being physically active from family is more important for mental health among women than support from other sources," the researchers conclude.

Reuters Health