If you are finding it hard to get time to do exercise on weekdays, do not give up the habit on weekend thinking it may not yield any benefit. Researchers have found that just one hour of exercise every week can help prevent depression.

The results, published in the American Journal of Psychiatry, showed that people of all ages can gain mental health benefits from even small amounts of exercise.The analysis involved 33,908 Norwegian adults who had their levels of exercise and symptoms of depression and anxiety monitored over 11 years.The team found that 12 per cent of cases of depression could have been prevented if participants undertook just one hour of physical activity each week."We've known for some time that exercise has a role to play in treating symptoms of depression, but this is the first time we have been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression," said lead author Samuel Harvey, Associate Professor at Black Dog Institute and University of New South Wales in Australia.

"These findings are exciting because they show that even relatively small amounts of exercise - from one hour per week - can deliver significant protection against depression," Harvey said.The researchers believe that the combined impact of the various physical and social benefits of physical activity could be linked to mental health benefits of exercise."If we can find ways to increase the population's level of physical activity even by a small amount, then this is likely to bring substantial physical and mental health benefits," Harvey added.With sedentary lifestyles becoming the norm worldwide, and rates of depression growing, these results are particularly pertinent as they highlight that even small lifestyle changes can reap significant mental health benefits, Harvey said.