In part one we finished with evidence showing endurance exercise activates the endocannabinoid system in humans. This has been proposed as an explanation for the altered mental status that accompanies intense exercise. Let’s now continue with that line of reasoning.
We know that the endocannabinoid system reduces pain sensations equivalent to that of morphine[ref]2004; Br J Sports Med 2004;38:536-541[/ref]. CB1 receptors have been found in abundance along peripheral nerves that transmit pain sensations as well as in central regions of the brain modulating pain signaling. They also clearly alter emotional states implying that this system may account for some of the effects that exercise produces.
Due to the resolve of scientists over the last decade we now know that there are CB receptors in muscle, skin, endothelial cells (lining blood vessels), and lung tissue suggesting a possible role for this system in mediating certain physiological responses to exercise[ref]IBID[/ref].
Studies have revealed that exercise suppresses pain, induces sedation, reduces stress, and elevates mood[ref]IBID[/ref]. These are all symptoms of endocannabinoid activation as well. This reinforces a cannabinoid model for helping to explain an exercise induced high.
As a certified gym-rat myself, I unscientifically lumped both the runner’s high and the exercise-induced high together. The latter would be from any form of exercise that is not a repetitive, rhythmic effort such as resistance training, tennis, basketball, heavy bag work, etc. However, the two highs may be quite different in origin.
The runner’s high may have more to do with endocannabinoids. While the run-of-the-mill exercise induced high may have more to do with growth hormone, dopamine, or testosterone release.
It’s clear that both produce a wonderful feeling of contentment and well-being. Yet, the long distance runner can boast an extraordinary type of mental state where one feels omnipotent and ecstatic, even blissful. I have had this experience only during running, and it’s pretty nice I must admit. I can’t approach that delightful state doing Bikram yoga, karate, or resistance training even after hours of high intensity work.
Therefore, it appears as if the cannabinoids might weigh in more for long distance, rhythmic events against gravity (swimming does not produce a runners high). While other contenders such as HGH release, fit the calm sense of well-being from other forms of exercise like peak fitness cycles (running hills for example) or weight training.
Furthermore, the high from weight training for example, kicks in after the event is over not during the actual grunting and straining. The runner’s high clearly occurs during the event and not after. This may be one of the key puzzle pieces needed to ferret out its origins.
Corroborating this idea comes from studies which show that the cannabinoids are activated the most from tissue damage as seen when runners pound their feet for miles.
Bearing on this problem, evidence is accumulating that cannabinoids induce analgesia by acting through CB1 receptors located in skin. This mechanism might suggest that painful stimuli to the skin are particularly potent in activating endocannabinoid antinociception [pain relief][ref]IBID[/ref].
What about the tissue damage from martial arts or rugby? Clearly we see some serious tissue being thumped when participating in these activities. What do these forms of exercise produce? At this point we do not know what other events produce high levels of endocannabinoids since they have not been studied yet. Only further testing will tell us if the endocannabinoid system is engaged in these different forms of exercise.
However, it’s unlikely that they will demonstrate high endocannabinoid levels since the powerful runner’s high isn’t usually associated with these sports.
As an interesting aside, the only other activity that I can think of that produces a profound sense of bliss is meditation. But doesn’t smoking pot (I’ve read) sometimes do this? In a future article I’ll explore the relationship between the bliss of inner peace through meditation and the endocannabinoid system.
Yet, all types of exercise produce a calm state of well-being. Soon we’ll see that, as we say farewell to the endorphin era and bid adieu to the endocannabinoid age, the cannabinoids will most assuredly play some role in producing it.