What Exercise Does To Your Brain: Endocannabinoids, Neurogenesis, and Mood Enhancement

This podcast episode, hosted by Dr. Tracey Marks, a psychiatrist, delves into the profound effects of exercise on the brain, moving beyond the common misconception of endorphins as the primary driver of post-exercise well-being. Dr. Marks explains that while endorphins do reduce pain perception during intense activity, they do not cross the blood-brain barrier and therefore do not directly impact mood. Instead, the euphoric and relaxed feelings experienced after moderate to vigorous exercise are attributed to the release of endocannabinoids, which are naturally produced by the body and can readily cross the blood-brain barrier to activate cannabinoid receptors, similar to the effects of cannabis compounds like THC and CBD.

The discussion highlights the distinction between endogenous (body-produced) and exogenous (external source) cannabinoids, with AEA and 2-AG being the most studied endogenous types. The core argument is that vigorous exercise essentially stimulates the body to produce its "homemade cannabinoids," leading to mood-lifting and anxiety-reducing effects. Furthermore, the episode emphasizes the long-term benefits of regular exercise, particularly its role in triggering brain-derived neurotrophic factor (BDNF), which promotes neurogenesis—the growth of new brain cells and regeneration of damaged ones. This neurogenesis is linked to an increase in hippocampus size, a crucial brain region for memory, learning, emotional processing, and psychological insight, with a smaller hippocampus being a hallmark of depression.

Dr. Marks provides practical recommendations for exercise intensity and duration, citing guidelines from the Centers for Disease Control and Prevention and the Department of Health and Human Services. She advises 150 minutes per week of moderate-intensity exercise (where one can talk but not sing) or 75 minutes per week of vigorous-intensity exercise (where talking is difficult). Examples for each intensity are given, such as brisk walking or dancing for moderate, and running or swimming laps for vigorous. The importance of aerobic activity is stressed for activating the endocannabinoid system and promoting neurogenesis, though any activity is acknowledged as better than none.

In essence, the podcast reframes exercise not just as a physical activity but as a powerful neurobiological intervention. It offers a scientific explanation for its antidepressant and anxiolytic effects, linking it to specific brain chemicals and structural changes. The broader implication is that regular, appropriately intense exercise is a vital, natural tool for enhancing mental health, cognitive function, and emotional resilience, providing a deeper understanding of the mind-body connection and empowering listeners with actionable advice for brain health.

For years, it was hypothesized that this was due to the release of endorphins, which is your body's natural opiate.

Well, it turns out the runner's high really isn't that common among runners, but anyone can experience a relaxed feeling after moderately intense exercise, not from endorphins, but from endocannabinoids.

Your brain is very selective about what that allows to pass through the gate.

So you can think of vigorous exercise as making your own strain of cannabis, sort of.

Your homemade cannabinoids have a mood lifting and anxiety reducing effect, but it gets better.

Regular exercise has a longer effect on improving mood and anxiety because it triggers brain derived neurotropic factor, which causes neurogenesis.

In the brain world, you want to have a big hippocampus. A small hippocampus is considered a hallmark of depression.

It not only controls learning tasks like problem solving, but controls your ability to process emotion and allows you to level up your psychological insight.

The Centers for Disease Control and Prevention and other sources recommend 150 minutes a week of moderate intensity exercise or 75 minutes a week of vigorous intensity.

Now, I will say any kind of activity is better than no activity.

So, a slow walk in your neighborhood still brings you some benefit, but to activate the Endocannabinoid System and increase neurogenesis, you need some aerobic activity.