High Reps: How Marijuana Affects Exercise

When my daughter was in high school, she was around all different kids of weed smokers. One person she had in her class ran track. He said that he would smoke large amounts of weed before running because he couldn’t feel the pain in his legs which would keep him running longer. He said that smoking marijuana helped him be a better athlete.

While it is very difficult to study marijuana due to its recent legal status, however, there is some evidence that we can look at. Marijuana is a drug with chemicals called cannabinoids. It affects the receptors in the brain known as the endocannabinoid receptors that create chemicals similar to the ones found in marijuana. These receptors are similar to the chemicals released in your brain when a runner gets a “runners high.” This means that smoking before one goes for a run could make the experience more pleasurable.

However, studies have conducted where they gave people marijuana and had them take an endurance test on a stationary bike, and compared the results to cyclists with no marijuana, and cyclists that were given a placebo endurance drug, the results showed that the cyclists had a higher chance of “burning out” sooner. The people who were given a placebo drug had the most endurance.

It was also shown that people who were exercising while high on marijuana overall had higher blood pressure and a higher heart rate than people who were not high on marijuana. This can pose a risk and be problematic for people with or at risk for coronary heart disease. The journal of American Heart Association published a study showing that marijuana highly increases the risk of heart attack, heart rhythm disorders, and stroke. The American Heart Association states that within an hour of smoking marijuana, the risk of heart attack went up 480%. Since exercise raises the heart rate, and marijuana can raise the heart rate up to 100 points, it can be very dangerous for someone’s heart to exercise while high on marijuana.

It is true that marijuana can stop signals to the brain of pain, which is why marijuana can be prescribed for terminal patients with cancer to ease the pain. This is why my daughter’s friend smoked weed before running, so his legs wouldn’t hurt. However, this can be dangerous since pain is an important signal from your brain. When people overexert themselves, pain tells them that something is wrong in their body and is a signal to stop. Someone who is high on marijuana might not be able to identify these signals in time. This can be a problem leading to long-lasting joint pain or exercise related injury.

Marijuana is a psychoactive drug. This means that it can slow reaction time and processing time. This makes it more difficult for people’s brains to process incoming information. In a study done on people’s processing time, they had people take varying amounts of marijuana, and then go through a virtual maze. What they found is that people who have more than 17mg took longer to go through the maze and bumped into walls more often than people who had no marijuana in their system.

While marijuana may help with pain management, this can be dangerous since pain is important, especially when exercising. Overall, marijuana while exercising seems to do more harm than good. Better to stick to a good protein shake!


Abram, William. “Is Marijuana Bad for Your Heart?” Everyday Health, Everyday Health, 23 Apr. 2014

“Endocannabinoids.” Egyptian Journal of Medical Human Genetics, Elsevier

“What Happens When You Workout High?” YouTube, YouTube, 6 Oct. 2016