Endocannabinoid and Affective Responses to Preferred and Prescribed Exercise

Abstract

Evidence suggests that self-selected or “preferred” exercise may be more effective in eliciting positive mental health outcomes than prescribed exercise. There are several purported mechanisms underlying affective changes after exercise, though the psychological effects of the endogenous cannabinoid system, which is activated by acute exercise, are largely unknown. PURPOSE: To examine the effects of a preferred versus a prescribed exercise bout on the endocannabinoid (eCB) system and affective outcomes. METHODS: Thirty-sex men and women (21± 4yrs) participated in 3 study visits. During the first visit, they completed a demographic questionnaire, the State-Trait Anxiety Inventory (STAI), and the Profile of Mood States (POMS), before undergoing a submaximal VO2 treadmill test. The next two visits were randomized and counterbalanced, with participants performing both preferred and prescribed exercise on separate days. For the preferred bout, participants self-selected their exercise intensity and duration. For the prescribed bout, they exercised for 45 minutes at 70-75% of their estimated VO2 max. The STAI, POMS, and blood draws were completed before and after exercise sessions. Data were analyzed using a 2 (session) x 2 (pre/post exercise) repeated measures ANOVA and Pearson’s correlations. RESULTS: Both preferred and prescribed exercise elicited positive mood improvements compared to pre-exercise values, but post-exercise reductions in anger were greater in the preferred condition (p < 0.05). Likewise, both preferred and prescribed exercise resulted in significant increases (p < 0.01) in eCBs (AEA, 2-AG) and related biogenic lipids (PEA, OEA, and 2-OG). However, increases in AEA (p = 0.02) and OEA (p = 0.02) were larger in the prescribed condition. 2-AG levels were found to negatively correlate with confusion, depression, and tension in the preferred condition (p < 0.05). In the prescribed condition, OEA was associated (p < 0.05) with negative mood outcomes, whereas PEA was associated (p < 0.05) with positive mood outcomes. CONCLUSIONS: This is the first study to demonstrate that preferred exercise activates the eCB system and the first to report an increase in 2-AG and 2-OG after acute aerobic exercise. These results provide initial evidence that eCBs and their related lipids may be involved in affective changes after exercise. Supported by the American College of Sports Medicine and the Virginia Horne Henry Fund