There is increasing evidence to suggest that regular physical exercise has psychological benefits, with more active people illustrating lower levels of depression than sedentary people [659-661]. As mentioned previously, exercise is relatively low-risk, is associated with wide physical health benefits, and research has demonstrated exercise to be as effective in reducing depressive symptoms as psychotherapy and antidepressants [185, 195, 662]. A Cochrane review concluded that physical activity (defined as aerobic, mixed, or resistance) was moderately more effective than control interventions for treating depression, with exercise equally as effective as psychotherapy or pharmacotherapy [663]. The UK NICE Guidelines for depression recommend structured, supervised physical activity programs, three times a week (45 minutes to 1 hour duration) for at least 12 weeks [650].
There is much evidence suggesting that physical activity improves levels of depression and anxiety [664, 665], both of which are risk factors for, and have been associated with, AOD use [51, 666]. Despite this association, there is little research that has examined the role of exercise among people with comorbid depression and AOD use disorders specifically. A study examining the effects of an 8-week structured exercise program (treadmill and weight training), on depression and anxiety symptoms among newly abstinent methamphetamine users in treatment, found that more exercise was significantly associated with greater reductions in depression and anxiety symptoms, compared with the control group (health education sessions), and compared with fewer exercise sessions [233].
Another study, examining the effect of a 10-week, 30-minute, exercise program (incorporating walking/ running, ball games, strength training) on quality of life in a sample of people attending residential AOD treatment for polydrug use, found a significant reduction in depression (from 78% to 36%) among those who completed the program [667]. This study highlights the difficulty involved in engaging comorbid populations in physical activity, which in general succeed in retaining only those with the fewest physical health problems [668]. However, the fact that 69% of participants completed the exercise component of this study does point to the feasibility of engaging and maintaining people with comorbid depression and AOD use disorders in programs incorporating physical activity [667].
A systematic review examining the effect of exercise-based interventions on AOD use found exercise was associated with overall improvements in depression [185]. Although these findings indicate that exercise is a potentially promising adjunctive treatment for people with comorbid depression, they also highlight the need for further well-conducted research to be undertaken in this area.