Many people experience post-exercise stress, pain, anxiety relief, and sometimes even euphoria. What is behind this so-called “Runner’s High”? New research on the neuroscience of exercise may surprise you.
“Runner’s High” has long been attributed to endorphins. These are chemicals that are naturally produced in humans and other animals after exercise and in response to pain and stress.
However, a new study from my lab summarizes nearly 20 years of research on this topic. We have found that exercise reliably increases the levels of the body’s endogenous cannabinoids, the molecules that help maintain the balance between the brain and the body. This is a process called “homeostasis”. This natural chemical boost may better explain some of the beneficial effects of exercise on the brain and body.
I am a neuroscientist at Wayne State University School of Medicine. In my lab, I am studying the role of the endogenous cannabinoid system in brain development and mental health, as well as stress regulation and anxiety disorders in children and adolescents.
This study affects everyone who exercises to reduce stress and should serve as a motivation for those who do not exercise regularly.
Health benefits of exercise
Decades of research have shown that exercise is beneficial to your physical health. These studies found a consistent association between varying amounts of physical activity and reduced risk of premature death with dozens of chronic health conditions such as diabetes, hypertension, cancer and heart disease. doing.
Recently, studies have shown that exercise is also very beneficial to mental health over the last two decades. In fact, regular exercise is associated with reduced symptoms of anxiety, depression, Parkinson’s disease, and other common mental health and neurological problems. Consistent exercise also improves cognitive ability, mood, stress reduction, and self-esteem.
What is behind these improvements in mental health is not yet clear. We find that exercise has many effects on the brain, including increased metabolism and blood flow, promotion of the formation of new brain cells (a process called neurogenesis), and increased release of some chemicals in the brain. I know.
Some of these chemicals are called neurotrophic factors, such as brain-derived neurotrophic factors. BDNF is complexly involved in the “plasticity” of the brain, a change in the activity of brain cells, including those related to learning and memory.
Scientists have also shown that exercise increases blood levels of endorphin, one of the body’s natural opioids. Opioids are chemicals that act in the brain and have many benefits, including helping to relieve pain. Some early studies in the 1980s contributed to the long-standing general belief that this endorphin release is associated with the euphoria known as runners high.
But scientists have long questioned the role of endorphins in runners’ high senses. This is because endorphins cannot enter the brain through the blood-brain barrier, which protects the brain from toxins and pathogens. Therefore, endorphins may not be the main driving force for the beneficial effects of exercise on mood and mental state.
This is where our and other studies point out the role of cannabinoids in the natural version of our body, called endocannabinoids.
The amazing role of endogenous cannabinoids
You may be familiar with cannabinoids like tetrahydrocannabinol-well known as THC-a psychoactive compound of cannabis ( Cannabis Sativa L. Plants) Make people feel high. Or you may have heard of cannabidiol, commonly known as CBD, an extract of cannabis that is infused into some foods, medicines, oils, and many other products.
However, many are unaware that humans have also created their own versions of these chemicals called endocannabinoids. These are small molecules made of lipids (or fats) that circulate in the brain and body. “End” refers to what is produced in the body, not in a plant or laboratory.
Endogenous cannabinoids act on cannabinoid receptors in the brain and throughout the body. They have a variety of effects, including pain relief, anxiety and stress relief, and learning and memory enhancement. It also affects hunger, inflammation and immune function. Endogenous cannabinoid levels can be affected by food, time zone, exercise, obesity, injury, inflammation and stress.
It’s worth noting that you shouldn’t stop running or biking and rely on smoking or consuming cannabis instead. Endogenous cannabinoids lack the unwanted effects of heightening, such as mental illness.
Understanding Runners High
Studies in human and animal models point to endorphinoids as runners-high star players rather than endorphins.
These sophisticated studies show that when opioid receptors are blocked (in one case, by a drug called naltrexone), people still experience euphoria and reduce post-exercise pain and anxiety. Conversely, studies have shown that blocking the effects of cannabinoid receptors reduces the beneficial effects of exercise on euphoria, pain, and anxiety.
Some studies have shown that exercise increases the levels of endogenous cannabinoids that circulate in the blood, but reports inconsistent findings and shows that different endogenous cannabinoids produce different effects. Some have been reported. It’s also unclear if all types of exercises, such as cycling, running, and resistance exercises such as weightlifting, will produce similar results. And whether or not you experience the same endogenous cannabinoid boost with or without existing health conditions such as depression, PTSD, and fibromyalgia is an open question.
To address these questions, Shreya Desai, an undergraduate student in my lab, led a systematic review and meta-analysis of 33 published studies on the effects of exercise on endogenous cannabinoid levels. We compared the effects of “acute” exercise sessions such as 30-minute runs and cycles with those of “chronic” programs such as 10-week running and weightlifting programs. We isolated them because different levels and patterns of movement can have a very clear effect on the endogenous cannabinoid response.
Acute exercise was found to consistently increase endogenous cannabinoid levels throughout the study. The effects are most consistent with the chemical messenger known as anandamide, the so-called “bliss” molecule, with some names for its positive mood effects.
Interestingly, this exercise-related boost of endocannabinoids was observed with and without various types of exercise such as running, swimming, weightlifting, and existing health conditions. Although few studies have investigated the intensity and duration of exercise, moderate levels of exercise intensity, such as cycling and running, appear to be more effective than low-intensity exercise, such as walking at low speeds and low slopes. Raises endogenous cannabinoid levels. This shows that it is important to keep your heart rate up for at least 30 minutes to get the full benefit. That is, between about 70% and 80% of your age-adjusted maximum heart rate.
There are still many questions about the link between endogenous cannabinoids and the beneficial effects of exercise. For example, there was no consistent effect on how chronic exercise regimens, such as a 6-week cycling program, affect endogenous cannabinoid levels at rest. Similarly, the minimum amount of exercise to enhance endogenous cannabinoids and the length of time these compounds remain elevated after acute exercise are not yet clear.
Despite these unanswered questions, these findings take researchers one step closer to understanding how exercise can help the brain and body. And they provide an important motivation for making time for exercise during the holiday rush.
Hilary A. Marusac, Associate Professor of Psychiatry and Behavioral Neuroscience, Wayne State University
This article was first published in The Conversation
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