Study designs of evaluations included in the review
Randomised controlled trials (RCTs) were eligible for inclusion.
Specific interventions included in the review
Studies of exercise interventions compared with a nonactive comparator, such as waiting-list or placebo treatment, low-level exercise or health education, were eligible for inclusion. The included studies were of exercise alone (such as walking, running, jogging and progressive resistance training) or exercise as an adjunctive treatment to drug therapy. The included studies of exercise alone varied in exercise frequency from two to four times per week and in duration from 20 to 45 minutes (where this was reported). The most common comparator was no treatment or waiting-list; other studies used low-level exercise or health education. Studies that did not meet the inclusion criteria for the meta-analysis were included in a separate narrative synthesis but are not considered in this abstract.
Participants included in the review
Studies of people with affective disorders were eligible for inclusion provided the symptoms were not secondary to another clinical disorder (e.g. drug abuse). One study was excluded because the symptoms of depression were not considered severe enough (Beck Depression Inventory score of less than 11). The included studies were of in-patients and out-patients, mainly with symptoms of depression. Three studies considered only older depressed patients and two studies only women with depression.
Outcomes assessed in the review
The outcome of interest was depression and only studies that reported baseline and follow-up scores were included. The included studies used the Beck Depression Inventory, Hamilton Rating Scale for Depression, Edinburgh Postnatal Depression Scale, Self-Rating Depression Scale and Symptom Checklist Revised.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.