Why exercise helps depression

Many studies have suggested exercise can help alleviate depression. Lynette Craft (Michigan State University) wanted to find out the psychological mechanisms that might underlie this benefit.

Nine women with moderate depression underwent a nine-week exercise programme. Two days per week the participants undertook moderate-intensity (30mins) exercise on cycles and treadmills, and were taught stretching, and how to monitor their heart rate. One day a week they exercised at home. To facilitate a 'mastery experience', they were gradually given greater control over their exercise.

A control group of 10 depressed women did not complete the exercise programme. Both the control and exercise participants were on antidepressant medication, and had been for an average of 47 months.

A self-report assessment of depression symptoms (BDI-II) showed the exercise group's depression was significantly reduced both at three weeks after the programme start, and at the programme end. By contrast, the control group's depression symptoms remained unchanged.

'Coping self-efficacy' is a measure of a person's belief that they can cope with their depression. Craft found that the exercise participants' coping self-efficacy was increased at three and nine weeks into the programme, and that it correlated with their reduced depression symptoms, thus suggesting a possible mechanism for the exercise's beneficial effect. "Learning and mastering new health-related skills may have given them the confidence necessary to master new techniques to deal with their symptoms", Croft said. The exercise participants had also stopped thinking about their worries so much (i.e. ruminating) but this didn't correlate with their depression symptoms.

Further reading

Craft, L.L. (2005). Exercise and clinical depression: examining two psychological mechanisms. Psychology of Sport and Exercise, 6, 151-171.