J.D. Meyer, K.M. Crombie, D.B. Cook, C.J. Hillard, & K.F. Koltyn
Medicine & Science in Sports & Exercise (2019); 51(9):1909-17
Exercise has been shown to reduce depression and is as effective as prescription drugs and behavioral therapies. The benefits of exercise on mood occur both acutely, after a single session, as well as chronically, after repeated sessions. However, the mechanisms by which exercise benefits mood are poorly understood. It is possible that benefits are mediated through the endocannabinoid system, which is activated by exercise and is associated with pleasurable and rewarding activities.
This study looked at endocannabinoid levels and mood in exercising depressed women to determine the relationships between endocannabinoid changes and mood states.
Who was it?
There were 17 women between the ages of 20 and 60 with Major Depressive Disorder (MDD). Some participants were taking antidepressant medications.
What was done?
Each woman performed two exercise sessions on a stationary bicycle: (1) 30 minutes at a moderate prescribed intensity, and (2) 30 minutes at a self-selected intensity. Sessions were separated by at least one week. Blood was taken and mood states were assessed before and after exercise.
Exercise done at a moderate prescribed intensity resulted in increased levels of several endocannabinoids which were associated with changes in mood states, including depression. These benefits lasted for up to 30 minutes after exercise. Some positive changes in mood were observed when exercise intensity was self-selected, but these were not associated with endocannabinoid changes, suggesting that moderate intensity exercise is needed to activate the endocannabinoid system.
This study confirms that exercise, either at a moderate or preferred intensity, improves mood. Mood changes are correlated with levels of some endocannabinoids in moderate intensity activity. This shows that activation of the endocannabinoid system is one of likely several ways in which exercise benefits mood. Other endocannabinoid system activating tools, such as CBD, also improve mood and may be combined with exercise for maximal benefit.