Active kids are 'less likely' to get depressed

Children who get more exercise may have fewer symptoms of depression than their less active peers, a recent study suggests.

Researchers used activity trackers to see how much physical activity children got, then interviewed kids and their parents to assess whether the children had symptoms of depression.

When kids got more physical activity at ages six and eight, they were less likely to have symptoms of major depressive disorder two years later, the study found.

"Our results indicate that increasing physical activity in children may prevent depression," said study leader Tonje Zahl, of the Norwegian University of Science and Technology in Trondheim.

Plenty of research has documented the potential for exercise to boost mood and help with depression for adults, but less is known about the ways activity may influence mental health in young children. Depression and other mental health disorders don't emerge until adolescence .

Researchers surveyed parents to assess children's mental health at age six, then did follow-up interviews with parents and kids at age eight and 10 to determine whether they had symptoms of depression.

They had data on 795 kids at age six, 699 at age eight and 702 at 10.

At ages six and eight children were asked to wear accelerometers to track their movements. The accelerometers showed at age six, kids typically got about 1.19 hours a day of moderate to vigorous physical activity and had 8.58 hours of sedentary time.

At age eight active time was 1.18 hours a day on average with 9.22 hours of sedentary time.

By age 10 active time dipped to 1.09 hours on a typical day with 9.94 hours of sedentary time.

Higher levels of moderate-to-vigorous physical activity at six and eight predicted fewer symptoms of major depressive disorder two years later, with every extra hour of such activity linked with a moderate decrease in symptoms. The study didn't find an association between inactivity and symptoms of depression, however.