(BMJ) - Aerobic exercise can work faster than drugs to lift depression, finds research in the British Journal of Sports Medicine.

Twelve people with severe depression that had lasted an average of nine months exercised daily for 10 days. Their average age was 49; seven of them were women. In 10 patients drugs had failed to substantially improve symptoms.

The exercise entailed walking on a treadmill for 30 minutes every day. Three minutes of intense activity were alternated with walking at half speed for three minutes. The intensity was increased as heart rate adapted to the training programme.

Depression severity was measured at the start and end of the programme, and patients also rated their mood at the beginning, middle, and end of the 10 days, using a recognised evaluation scale.

After 10 days, six patients were substantially less depressed, including five in whom drug treatment had been largely unsuccessful. Two were slightly less depressed, while the severity of symptoms remained the same in four patients. Overall, depression scores fell by a third, and self assessed scores fell by 25 per cent. Six patients asked to continue the programme.

The authors are at pains to point out that this is a small study. Nevertheless, they say that the extent of the improvement is impressive, given that antidepressants normally take two to four weeks to work. "The observed outcomes indicate a clinical benefit not obtainable with currently available pharmacological treatments," they conclude. And the programme might be particularly suitable for those in whom drug treatment does not seem to work, they say.