What is the Runner’s High? How cannabis explains a bizarre training phenomenon


Many people experienced a reduction in stress, pain and anxiety, and sometimes even euphoria after exercise. What is behind this so-called “runner’s high”? New research in the neuroscience of exercise may surprise you.

The “runner’s high” has long been attributed to endorphins. These are chemicals that are produced naturally in the bodies of humans and other animals after exercise and in response to pain or stress.

However, new research from my lab sums up nearly two decades of work on this topic. We have found that exercise reliably increases the body’s levels of endocannabinoids – which are molecules that work to maintain balance in the brain and body – a process called “homeostasis.” This natural chemical boost may better explain some of the beneficial effects of exercise on the brain and body.

I’m a neuroscientist at Wayne State University School of Medicine. My lab studies brain development and mental health, as well as the role of the endocannabinoid system in regulating stress and anxiety disorders in children and adolescents.

This research has implications for anyone who exercises for the purpose of reducing 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 for physical health. These studies find a consistent link between varying amounts of physical activity and a reduced risk of premature death and dozens of chronic health conditions, including diabetes, hypertension, cancer and heart disease.

While cannabinoids are produced in cannabis, they are also made in the human body.Iuliia Bondar / Moment via Getty Images

More recently – over the past two decades – increasing research shows that exercise is also very beneficial for mental health. In fact, regular exercise is associated with decreased symptoms of anxiety, depression, Parkinson’s disease, and other common mental health or neurological problems. Regular exercise is also linked to better cognitive performance, better mood, reduced stress, and improved self-esteem.

It is not yet clear what is behind these improvements in mental health. We know that exercise has a variety of effects on the brain, including increasing metabolism and blood flow, promoting the formation of new brain cells – a process called neurogenesis – and increasing the release of several chemicals in the brain.

Some of these chemicals are called neurotrophic factors, such as neurotrophic factors derived from the brain. BDNF is closely involved in the “plasticity” of the brain or in changes in the activity of brain cells, including those related to learning and memory.

From the Dana Foundation: “How Exercise Affects the Brain”

Scientists have also shown that exercise increases blood levels of endorphins, one of the body’s natural opioids. Opioids are chemicals that work in the brain and have a variety of effects, including helping to relieve pain. Some early research in the 1980s contributed to the long-held popular belief that this release of endorphin is related to the euphoric sensation known as runner’s euphoria.

However, scientists have long questioned the role of endorphins in high runner sensation, in part because endorphins cannot pass through the brain through the blood-brain barrier, which protects the brain from toxins and pathogens. . Endorphins are therefore unlikely to be the primary driver of the beneficial effects of exercise on mood and mental status.

This is where our research and that of others highlight the role of natural versions of cannabinoids in our bodies, called endocannabinoids.

The surprising role of endocannabinoids

Andrew Brookes / Image source / Getty Images

You may be familiar with cannabinoids such as tetrahydrocannabinol – better known as THC – the psychoactive compound in cannabis (from Cannabis sativa L. plant) that makes people feel high. Or you may have heard of cannabidiol, commonly known as CBD, a cannabis extract infused into certain foods, drugs, oils, and many other products.

But many people don’t realize that humans also create their own versions of these chemicals, called endocannabinoids. These are tiny molecules made up of lipids – or fats – that circulate in the brain and body; “Endo” refers to those produced in the body rather than from a plant or a laboratory.

Endocannabinoids work on cannabinoid receptors throughout the brain and body. They cause various effects, including pain relief, reduction of anxiety and stress, as well as improved learning and memory. They also affect hunger, inflammation, and immune function. Endocannabinoid levels can be influenced by food, time of day, exercise, obesity, injury, inflammation, and stress.

It should be noted that one should not be tempted to give up a run or cycle and resort to smoking or ingesting cannabis instead. Endocannabinoids do not have the side effects that come with getting high, such as mental retardation.

Understanding the runner’s high

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Studies in humans and animal models indicate that endocannabinoids – not endorphins – are the star players in runner’s euphoria.

These elegant studies demonstrate that when opioid receptors are blocked – in one example by a drug called naltrexone – people still experience euphoria and decreased pain and anxiety after exercise. On the flip side, studies have shown that blocking the effects of cannabinoid receptors reduced the beneficial effects of exercise on euphoria, pain, and anxiety.

While several studies have shown that exercise increases the levels of endocannabinoids circulating in the blood, some have reported inconsistent results, or that different endocannabinoids produce varying effects. We do not yet know if all types of exercise, such as cycling, running, or resistance training such as weight lifting, produce similar results. And it’s an open question whether people with or without pre-existing health conditions like depression, PTSD, or fibromyalgia experience the same endocannabinoid surges.

To answer these questions, an undergraduate student in my lab, Shreya Desai, led a systematic review and meta-analysis of 33 published studies on the impact of exercise on endocannabinoid levels. We compared the effects of an “acute” exercise session – such as a 30-minute run or cycle – with the effects of “chronic” programs, such as a 10-week running or weightlifting program. We separated them because different levels and patterns of exertion could have very distinct effects on endocannabinoid responses.

We found that acute exercise consistently increased endocannabinoid levels in all studies. The effects were most consistent for a chemical messenger known as anandamide – the so-called “happiness” molecule, which has been named, in part, for its positive effects on mood.

Interestingly, we have observed this exercise-related increase in endocannabinoids in different types of exercise, including running, swimming, and weight lifting, and in individuals with or without pre-existing health conditions. Although only a few studies have looked at the intensity and duration of exercise, it appears that moderate levels of exercise intensity, such as cycling or running, are more effective than low-intensity exercise. , such as walking at a slow speed or on a low incline, when it comes to increasing endocannabinoid levels. This suggests that it’s important to keep your heart rate elevated – that is, between about 70-80% of your age-adjusted maximum heart rate – for at least 30 minutes to get it all out. advantages.

There are still many questions about the links between endocannabinoids and the beneficial effects of exercise. For example, we haven’t seen consistent effects on how a chronic exercise regimen, such as a six-week cycling program, might affect resting endocannabinoid levels. Likewise, it is not yet clear what the minimum amount of exercise is to increase endocannabinoids, and how long these compounds remain elevated after acute exercise.

Despite these open questions, these findings bring researchers closer to understanding the benefits of exercise for the brain and body. And they provide significant motivation for taking the time to exercise during the vacation rush.

This article was originally published on The conversation through Hilary A. Marusak at UCL. Read the original article here.


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