The rush you feel after a hard run or a great workout is usually chalked up to endorphins, the body’s natural happy hormone. They’re responsible for the good mood you feel when you experience pleasure, in the form of exercise, eating, or even sex. However that runner’s high may only be partially due to endorphins.
A number of studies are starting to point to the endocannabinoid system (ECS) for being primarily responsible for the rush. Particularly, the endogenous cannabinoid anandamide, also known as the bliss molecule, which may be a key element in that rush we feel from the good things in life.
A study published in Neuroscience examined how exercise affects pain reception. The results showed that cannabinoid receptors on immune cells in the spinal cord were activated after exercise, which consequently had a numbing effect on exercise-related pain. While previous research had suggested that anandamide played a role in runner’s high, this study was first in showing the immunoregulatory effects of CB2 receptors.
The level of physical activity also matters when it comes to the activation of the ECS and the increase in the bliss molecule. This explains why mild exercise like leisurely walks do not produce elevated ECS activity. The study also found that injury actually increased ECS activity when compared to non-injured subjects.
A study done on mice in Germany also found that they were less sensitive to pain and showed decrease anxiety levels after running, which they did for fun. When researchers introduced a drug to block the ECS system, the anxiolytic effect was not present anymore and they were still sensitive to pain. However when their opioid receptors, those responsible for the endorphins, there was no different to the post-run high.
The study found a correlation between how far the mice ran and how much their pain tolerance increased. At up tom three miles a day, the scientists concluded that this could explain how humans have evolved to move and cover longer distances, thanks to reduced pain and lowered anxiety during long distance running.
An Evolutionary Advantage
Runner’s high may have been an integral part in helping our species survive. Apart from motivating us to move, it helps us sustain intensive aerobic activity by reducing pain and acting as a neurobiological reward to keep us healthy, and alive!
Too Much of a Good Thing
While the benefits are obvious, there may be a downside to runner’s high; addiction. Some people get so addicted to the feeling after a hard workout they end up doing long term damage to their bodies. This is also observed in mice, with some choosing running over anything else, sometimes even to the point of death. This discovery led to the hypothesis that exercise may be as addictive as morphine. Researchers at the University of Arizona identified a subtype of people called ‘obligatory runners’, those who had a compulsive drive to run that preempted fulfilment in other life areas, or those who run to the point of inflicting physical damage to themselves.
Weighing It Up
At the end of the day, the pros outweigh the cons in this argument. Anandamide results in runner’s high, but also results in a wide range of health benefits, like reduced anxiety, and even the ability to treat patients with acute schizophrenia.
As more research is done into the inner workings of the endocannabinoid system, we will undoubtedly learn more about how it affects various bodily functions and changes more of what we know about our bodies.