A small number of studies with relatively small samples have examined the effect of exercise on bipolar disorders. Ng and colleagues [584] conducted a small, retrospective chart review, and found that depression and anxiety improved among bipolar inpatients who participated in a voluntary 40-minute, supervised group walking activity, every weekday morning, compared to non-walkers. However, there was no clinical difference in overall improvement between walkers and non-walkers [584]. A small open trial examining the short term effects of aerobic training on depression and bipolar disorder found that aerobic training slightly improved symptom severity for those with bipolar disorder [585]. Another small RCT examined the effect of a short-term, maximum endurance exercise program as an accompanying treatment to pharmacotherapy, and found that, relative to control (gentle stretching and relaxation), depression scores were significantly reduced among the exercise group [586].
Although the aforementioned studies provide evidence to suggest that regular physical activity can assist in the reduction of depressive symptoms, there is preliminary research pointing to the existence of possible exacerbation of mania among some people [587, 588]. Although exercise may be beneficial in redirecting excess energy for some, others found their manic symptoms were aggravated, potentially risking a cycle of manic and hypomanic symptoms [589]. It has been suggested that the exacerbation of manic symptoms may be due to direct effects on mood, or indirectly on excessive goal-focused activities, which can be a risk pathway for bipolar disorder [590, 591]. However, these preliminary findings originate from a small qualitative study and require further empirical evidence, with some participants in the study finding exercise calming [587]. No research has been conducted to examine the efficacy of exercise among people with comorbid bipolar and AOD use; however, given the unknown and potentially risky relationship with mania, physical activity among people with comorbid disorders should be closely monitored.