In the aerobic exercise (AE) group, the intervention consisted of 30 minutes of daily brisk walking or jogging. This was done individually and supervised. Participants who missed \> 2 training sessions were considered as non-completers. Exercise intensity had to be maintained within 65%-75% of age-predicted maximal heart rate, as commonly prescribed in studies using aerobic exercise to alleviate depression. Heart rate monitoring devices were used.
Participants in the stretching (ST) group also performed a daily 30 minutes exercise program but this was "sham" exercise, consisting of stretching exercises. Several muscle groups (thighs, calves, gluteal, shoulders, back) were stretched for 60 seconds, with equivalent resting intervals between stretching series. These activities were also individual and supervised. As was the case for the AE intervention, participants who missed \> 2 training sessions were considered as non-completers.
Participants in the control (NI) group received no intervention other than prescribed medication.
All participants started antidepressants within less than 2 weeks before study entry.
