In 2021, the International Olympic Committee (IOC) banned American sprinter, Sha’Carri Richardson, from the Tokyo Olympics after she tested positive for marijuana.
This naturally led to a media brouhaha with some folks rebuking the IOC for banning an athlete for a recreational drug, and others blasting Richardson for being so careless as to put a banned substance in her body right before the Olympics.
This also quickened a longstanding debate in sports: is marijuana performance enhancing?
Many gym-goers are curious to know the answer to a related question: will marijuana interfere with my gains?
In this article, we’re going to dive into the scientific research to give you evidence-based answers to both questions. You’ll learn what marijuana is, whether it enhances athletic performance or impedes muscle growth, and more.
Table of Contents
“Marijuana” refers to the dried leaves, flowers, stems, and seeds of the Cannabis sativa or Cannabis indica plant—a plant that contains the mind-altering chemical tetrahydrocannabinol (THC).
The Chinese have used marijuana as an analgesic (pain-relieving) and psychoactive drug since around 2700 BC. Today, marijuana is the most widely used illicit drug globally. An estimated 188 million adults worldwide used marijuana in 2017, which is just under 4% of the global adult population.
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There are several ways that marijuana may affect performance. Let’s consider each separately.
In a review conducted by scientists at St. Vincent’s Hospital Medical School, researchers analyzed the results of 15 studies and found that marijuana had no positive effects on aerobic performance. Specifically, the researchers found that smoking marijuana hastens fatigue, increases perceived exertion, decreases work capacity (the amount of exercise you’re able to complete), and makes you feel dizzy, which can prevent you from completing your workout.
Another review conducted by scientists at the University of Toronto examined four studies that looked at marijuana’s effect on aerobic performance and found that two studies showed marijuana had no effect, and two studies showed marijuana negatively impacted performance.
Finally, a recent umbrella review (a review of several reviews) concluded that:
“Cannabis consumption has an ergolytic effect on exercise performance and therefore does not act as a sport performance enhancing agent as raised by popular beliefs. Thus, cannabis consumption prior to exercise should be avoided in order to maximize performance in sports.”
Furthermore, research shows that long-term marijuana smoking can severely impair respiratory health. While this isn’t direct proof that marijuana use stymies aerobic performance, it makes it difficult to see how marijuana could have a favorable effect.
In other words, it’s not a stretch of the imagination to think that smoking grass hurts your lung health, and thus your endurance.
Only two studies have investigated the effect of marijuana use on strength. One found that strength was unaffected by marijuana use, while the other reported that “weakness was clearly demonstrated” after using marijuana, though it didn’t give more detail.
Both studies only measured grip strength and neither used athletes as participants, though, so it’s not clear if these results apply to weightlifters.
While it’s purely speculative, some researchers believe that marijuana may increase strength through bronchodilation (relaxing the muscles in the lungs and widening the airways).
Research shows that beta-2 agonists (drugs that cause bronchodilation) such as salbutamol, salmeterol, formoterol, and terbutaline can improve strength, sprint, and power performance in nonasthmatic people.
Finally, for strength to be effectively employed in a sporting context, you must be focused and precise. That is, you can be extremely strong but fail to express that strength effectively if you have trouble concentrating and using good technique.
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No studies have looked at the effects of marijuana on muscle growth, so it’s impossible to draw any firm conclusions about how grass affects your gains.
Even speculation is difficult because there’s so much conflicting research.
On the one hand, studies on how marijuana affects anabolic (muscle-building) hormones shows that THC drastically lowers testosterone in rats and rhesus monkeys. On the other hand, human trials are a mixed bag, with some showing THC lowers testosterone and growth hormone and others finding that it has no effect.
If we take these findings together with what we know about how marijuana might impact strength and your ability to train effectively, there’s enough reason to believe that marijuana could hinder your ability to build muscle (even indirectly), which means that you should probably steer clear of it if building muscle is your top priority.
Athletes have used cannabis to relieve pain for millennia (it was one of the ingredients in the “Fuscum Olympionico inscriptum,” or the Olympic Victors Dark Ointment used at the classic Olympics).
A large meta-analysis conducted by scientists at the University of Bristol that included 79 studies and a total of 6,462 participants found evidence that marijuana can treat pain and spasticity (muscle spasms).
Thus, marijuana may indirectly boost athletic performance by helping athletes deal with the aches and pains that accompany regular competition.
What’s more, research shows that smoking marijuana increases pain tolerance, which may also give athletes a competitive edge by allowing them to train and compete through pain that might sideline other athletes.
Sleep is essential for most athletes because it gives the body a chance to recover from the rigors of training and the brain a break from the pressure of regular competition.
Studies show that marijuana can increase sleep duration, which may improve performance by aiding recovery.
Marijuana lowers anxiety, which helps some athletes to reach a “flow state” and be more creative. It may also scrub “fear memories,” so athletes are less afraid of what might go wrong and more likely to perform without the fear of failure.
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Based on the weight of the scientific evidence, it’s reasonable to conclude that marijuana doesn’t improve athletic performance and may even prevent you from performing at your best (especially in endurance sports).
The only way that marijuana may indirectly boost performance is through its ability to promote recovery, which it primarily does by making it easier to sleep. It may also improve your ability to cope with pain, which could aid performance in some scenarios. However, if you’re injury-free, it’s unlikely to have any positive impact on your athletic abilities.
Some people believe that marijuana increases creativity and makes it easier to enter a “flow state,” though this is purely anecdotal and may not be the same for everyone (some studies show that smoking marijuana makes it more difficult to concentrate and hinders decision-making).
Many people think of marijuana as a mild drug with medicinal benefits with fewer adverse health effects than similar legal substances such as alcohol.
And while research shows that marijuana is effective at treating some medical conditions, including pain, anxiety, and depression, and safer than alcohol in some ways, it’s probably an overstatement to refer to marijuana as “safe.”
For example, research shows that regular long-term marijuana use is associated with . . .
- Changes in amygdala, hippocampal, and white and gray matter volume, and blood flow in the brain
- Changes in learning, attention, memory, and overall brain activity
- Disruptions in important brain chemicals such as glutamate, dopamine, N-acetylaspartate, myo-inositol, choline, and γ-aminobutyric acid
- Mental health related issues, like earlier onset of psychosis, depression, and anxiety
- Increased risk of stroke, atrial fibrillation, respiratory complications, chronic obstructive pulmonary disease, and testicular cancer
- Increased risk of tobacco and nicotine dependence
Most research shows that using marijuana either has no effect on your athletic performance or prevents you from performing at your best.
That said, using marijuana may improve your recovery and help you deal with pain better, which means it may indirectly enhance athletic performance in some situations.
There’s no research looking at how “weed” (marijuana) affects muscle growth directly.
However, marijuana may make you weaker (at least for a short time) and can make you less proficient at tasks that require coordination, both of which would hinder your ability to train effectively and could decrease the amount of muscle you build over time.
It may hinder how quickly you build muscle, though, by making . . .
- Your workouts feel more difficult
- You feel tired
- You weaker
- You less able to perform exercises effectively
Thus, it’s sensible to avoid marijuana if you want to gain muscle and strength as quickly as possible.
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