A mental health charity in Britain says increasing numbers of doctors are prescribing exercise for people with depression.
The Mental Health Foundation conducted a survey of 200 family doctors in England and found that 22% suggest exercise to help people with milder forms of the condition.
A similar survey three years ago found only 5% recommended exercise to alleviate depression.
The foundation says research has shown that exercise can help people with mild forms of depression by improving self-esteem and by relieving feelings of isolation which can exacerbate their depression; exercise is also known to encourage the release of endorphins the 'feel-good brain chemicals'.
At some point in their lives one in every four women and one in every six men will suffer from depression.
The Mental Health Foundation says it is important that doctors do not just prescribe antidepressants for patients, and other options such as an increased availability of exercise on prescription is needed.
Mental health experts say exercise can help people physically, socially and biologically.
The survey found that while 61% of doctors believe that exercise therapy can be beneficial many did not have access to an exercise referral scheme.
Two thirds of the doctors wished they had such a referral scheme as there had been a marked increase in the number of people asking whether exercise could help them.
Exercise programmes organised by the Mental Health Foundation are supported by funds from the Department of Health, but are only available in some parts of the country.
Under six new schemes patients are assigned a personal trainer who devises an appropriate exercise regime for them; the results of the schemes are due to be published next year.
The Mental Health Foundation says depression is a complex illness and it is important that doctors have a range of treatments to offer people with depression.
The Foundation says there is a real need for increased availability of exercise on prescription so that it is accessible alongside antidepressant medication and psychological therapies.