There is preliminary evidence to suggest that physical exercise may be beneficial for people with single disorder OCD. Several pilot studies have demonstrated that the combination of a six to 12-week moderate aerobic exercise program with psychotherapy or pharmacotherapy reduced OCD symptom severity, which was maintained up to six months follow-up [1268–1270]. One study found that significantly lower OCD symptoms, anxiety and negative mood levels were reported immediately following each 20-40 minute exercise session [1271]. Similarly, another RCT found that a 12-week aerobic exercise program was effective at reducing compulsions, mood and anxiety, to a greater extent than psychoeducation, though obsessions did not change, among adults with single disorder OCD [1272]. Further, the severity of OCD symptoms did not significantly differ between groups directly following the intervention [1273]. While promising, more rigorous research is necessary to evaluate the benefits of physical exercise, and there is no evidence to date on the efficacy of physical exercise for the treatment of co-occurring OCD and AOD use disorder specifically.