Moderate exercise improves mental health but overdoing it does more harm than good, researchers have found.
A huge study of 1.2million people found those who exercised were – on average – stressed and depressed on fewer days than those who did not.
But experts also discovered a threshold beyond which the benefits began to be reversed.
Those who did the most exercise – more than five times a week or more than three hours a day – actually had worse mental health than those who did nothing at all.
The scientists, led by experts at Yale University in the US and Oxford University, found that exercising for 45 minutes three to five times a week, was associated with the biggest benefits. Doing more than this saw the benefits decline.
The researchers, whose findings are published in the Lancet Psychiatry journal, believe excessive exercise might be linked to obsessive behaviour.
But they stressed that more moderate exercise was definitely beneficial. Even doing chores around the house or pottering in the garden cut the time spent depressed by 10 per cent, they found.
Dr Adam Chekroud, assistant professor of psychiatry at Yale, said: ‘Depression is the leading cause of disability worldwide, and there is an urgent need to find ways to improve mental health through health campaigns.
‘Exercise is associated with a lower mental health burden across people no matter their age, race, gender, household income and education level.
‘Excitingly, the specifics of the regime, like the type, duration, and frequency, played an important role in this association. We are now using this to try to … match people with a specific exercise regime that helps improve their mental health.’
The researchers tracked 1.2million people in the US and asked them about 75 different types of physical activity, ranging from childcare, housework, gardening and fishing to cycling, going to the gym, running and skiing.
Participants were also asked to estimate how many days in the past 30 they would rate their mental health as ‘not good’ based on stress, depression and emotional problems.
The scientists found that team sports reduced the time spent in poor mental health by 22 per cent, cycling by 21 per cent, and going to the gym by 20 per cent. Jogging resulted in a 19 per cent reduction and walking 18 per cent.
Dr Chekroud said: ‘Our finding that team sports are associated with the lowest mental health burden may indicate that social activities promote resilience and reduce depression by reducing social withdrawal and isolation.’
Professor Stephen Lawrie, head of psychiatry at the University of Edinburgh, said last night: ‘I suspect we all know people who seem “addicted” to exercise and if this starts to impact on other aspects of life – like foregoing social activities because one has to be up at the crack of dawn to run several miles – it might actually be bad for people.
‘Activity, and especially social and “mindful” exercise, is good for mental health. Every second day for 45 to 60 minutes might be optimal.’
© Associated Newspapers Ltd.