It is rather common knowledge these days that exercise is a great method of improving mood, reducing stress and depressive symptoms. Taking a look at fairly current science, there are three main mechanisms behind these feelings of relaxation, sedation, anxiolysis (reduction of pain), boundless energy and overall sense of well-being that exercise provides [1,2,3,4].
- Endorphin receptor activation [1,2]
- Endocannabinoid receptor activation [2,3]
- Elevated levels of phenylethylamine [2,4]
The first mechanism is the typical idea that endorphins (endogenous opioids) are elevated after exercise, which provide these feelings of ‘drug-like’ pleasantness and relaxation. After all, these endorphins do work in practically the same way as pain-killer medications. However, the receptors for these endorphins are also located in mood-regulating areas of the brain, which helps elevate overall feelings of well-being and not just anxiolysis and sedation [1,2].
Secondly, exercise has been shown to activate the endocannabinoid receptors through elevated levels of anandamide. Endocannabinoid receptors can also be stimulated through the use of THC (commonly found in marijuana) and produce those same ‘feel good’ sensations [2,3]. This is an incredible finding as it suggests that you don’t need to risk legal consequences with possibly illegal substances to chase a good high!
If you’ve ever felt an overwhelming feeling of energy, attention and excitement after exercise, you can owe that to the effects of an elevated level of phenylethylamine [2,4]. This amine is a main ingredient in mood-boosting medications that are used in the treatment of depression. So, if you’re feeling down or out of energy, a boost of exercise-induced phenylethylamine can be enough to kick you back into gear, for at least a little while. The half-life of phenylethylamine is quite short (around 5-10 minutes), but it can be enough for that kick in the backside you may need to get out of procrastination.
In case you were wondering, these effects were all observed as a result of aerobic exercise where test subjects were either running or pedalling on exercise cycles for 30-45 minutes at an intensity of 70-80% maximum heart rate (medium intensity). The consensus on resistance exercise is still to be observed, however these same mechanisms are likely to be present.
Sources:
1. Boecker, H; Sprenger, T; Spilker, M; Henriksen, G; Koppenhoefer, M; Wagner, K; Tolle, T (2008). The runner's high: opioidergic mechanisms in the human brain. Cerebral Cortex, 18(11), 2523-2531.
2. Dishman, R; O'Connor, P (2009). Lessons in exercise neurobiology: the case of endorphins. Mental Health and Physical Activity, 2(1), 4-9.
3. Sparling, P; Giuffrida, A; Piomelli, D; Rosskopf, L; Dietrich, A (2003). Exercise activates the endocannabinoid system. Neuroreport, 14(17), 2209-2211.
4. Szabo, A; Billett, E; Turner, J (2001). Phenylethylamine, a possible link to the antidepressant effects of exercise? British Journal of Sports Medicine, 35(5), 342-343.
