Many people have reported reduced stress, pain, and anxiety, as well as euphoria, after exercising.  What is the source of the so-called “runner’s high”?  You might be surprised by a new study on the neurobiology of exercise.  Endorphins have long been blamed for the “runner’s high.”  These are substances created in humans and other animals’ bodies as a result of exercise and in reaction to pain or stress.

A new study, on the other hand, summarizes nearly two decades of research on the subject.  It was discovered that exercise consistently raises levels of endocannabinoids in the body, which are substances that help the brain and body maintain balance, a process known as “homeostasis.”  Some of the good benefits of exercise on the brain and body may be explained better by this natural chemical surge.

Endocannabinoids’ Surprising Function

You may be familiar with cannabinoids like tetrahydrocannabinol (THC), a psychoactive component found in cannabis (derived from the Cannabis sativa L. plant) that makes people feel high, as well as cannabidiol (CBD).

Many people are unaware, however, that humans produce their own copies of these substances, known as endocannabinoids.  These are small lipid – or fat – molecules that circulate in the brain and body; “endo” refers to those created in the body rather than in a lab or from a plant.  Cannabinoid receptors are found throughout the brain and body, and endocannabinoids function on them. They have a wide range of benefits, including pain alleviation, anxiety and stress reduction, and improved learning and memory. Hunger, inflammation, and immunological function are all affected by them.  Food, time of day, exercise, obesity, injury, inflammation, and stress can all affect endocannabinoid levels.

Getting a Glimpse of the Runner’s High

Endocannabinoids, not endorphins, are the main factors in the runner’s high, according to human and animal studies.  These clever experiments show that even when opioid receptors are inhibited – for example, with the medication naltrexone – people still feel pleasure and have less pain and anxiety after exercising.  Blocking the actions of cannabinoid receptors, on the other hand, diminished the favorable benefits of exercise on pleasure, pain, and anxiety.

While numerous studies have found that exercise raises the levels of endocannabinoids in the blood, others have found mixed results or that various endocannabinoids have distinct effects.
We also don’t know if all sorts of exercise, such as cycling, jogging, or strength training like weightlifting, have the same effect.  It’s also unclear if persons with and without underlying health issues such as depression, PTSD, or fibromyalgia get the same endocannabinoid benefits.

A review on the influence of exercise on endocannabinoid levels

A systematic review and meta-analysis of 33 published research on the influence of exercise on endocannabinoid levels tried to answer these issues.  The review contrasted the impacts of “acute” activity – such as a 30-minute run or cycle – to “chronic” regimens, such as a 10-week running or weightlifting program.  Across investigations, acute exercise consistently increased endocannabinoid levels.  The benefits were most constant for anandamide, a chemical messenger known as the “bliss” molecule, which was named for its favorable effects on mood.  It was noticed this activity-related increase in endocannabinoids in people who did diverse sorts of exercise, such as running, swimming, and weightlifting, and in those who had and didn’t have previous health issues.

Although just a few studies looked at exercise intensity and duration, it appears that moderate-intensity activity, such as cycling or running, is more successful at raising endocannabinoid levels than lower-intensity exercise, such as walking at slow speeds or on a low slope. To enjoy the full advantages, maintain your heart rate high — between 70 and 80 percent of your age-adjusted maximal heart rate – for at least 30 minutes.

There are still a number of unanswered concerns concerning the relationship between endocannabinoids and exercise benefits. We didn’t detect consistent impacts for how a long-term exercise program, such as a six-week cycling program, affected resting endocannabinoid levels, for example.  Similarly, it’s unclear how much activity is required to increase endocannabinoids and how long these substances stay high following acute exercise.

Despite these unanswered problems, the findings advance researchers’ knowledge of how exercise improves the brain and body.  They also serve as a powerful motivation for fitting in exercise as part of our new years resolution!