To assess the benefit and harm of exercise training in adults with clinical depression.

The DEMO trial is a randomized pragmatic trial for patients with unipolar depression. Patients with unipolar depression (n=165) were allocated to supervised strength, aerobic, or relaxation training during a four-month period. The primary outcome was the Hamilton depression scale and the secondary outcome was percentage of absence from work.

At 4 months, the strength increased in the strength group and the maximal oxygen uptake increased in the aerobic group vs. the relaxation group. At 4 months the change in HAM-D17 was -1.3 (-3.7 to 1.2; p =.3) and 0.4 (-2.0 to 2.9; p= .3) for the strength and aerobic vs. the relaxation group. At twelve months, the differences were -0.2 (-2.7 to 2.3; p = .8) and 0.6 (-1.9 to 3.1; p = .6). At twelve months, the differences in absence from work was -12.1% (-21.1 to -3.1; p = .009) and -2.7% (-11.7 to 6.2; p = .5) for the strength and aerobic vs. the relaxation group.

These findings do not suggest a biologically mediated effect of exercise on symptom severity in depressed patients, but support a beneficial effect of strength training on work capacity.