Does Marijuana Affect Athletic Performance?


Chronic marijuana use is shown by one study to have no effect on aerobic or anaerobic performance. 

Marijuana use has been increasing in popularity over the last several years, especially with the legalization of recreational marijuana in large states such as Colorado and California. A study was recently conducted in Colorado to evaluate the effects of chronic marijuana use on anaerobic and aerobic fitness (Performance and Health Related Characteristics of Physically Active Males using Marijuana, 2018. Lisano JK, et al.).

Marijuana use is especially prevalent in young adults, the age when athletes are in their prime. In fact, 20% of young adults report using marijuana in the last month. In 1999, marijuana was added to the banned substances list by the World Anti-Doping Agency. More recently, marijuana was banned by the NCAA for college athletes in the US. Nonetheless, a one study found that 37% of NCAA Division I athletes reported using marijuana, with the prevalence higher in male athletes compared to female athletes. However, does marijuana really help improve athletic performance?

Marijuana is known to have a number of effects on the body. Marijuana use has been shown to be linked with higher rates of depression and anxiety, but also has successfully treated asthma, migraines, glaucoma and seizures. Marijuana has been used to treat nausea associated with chemotherapy, but its withdrawal can cause whats known as cyclic vomiting syndrome. Medical evidence supports the use of THC, the active ingredient in marijuana, in treating nausea and emesis, muscle spasms in adults with multiple sclerosis and chronic pain. Marijuana is also thought to have prenatal effects when used by pregnant women, although studies out of Jamaica where it used to control morning sickness dispute this. In terms of physiology, marijuana use causes an increase in the resting heart rate and acute use increases airway conductance. Marijuana is known to decrease oxidative capacity of mitochondria in skeletal muscle (and theoretically therefore aerobic performance). Chronic marijuana use decreases testosterone in males and raises cortisol (produced in response to stress).

In regards to performance, the aforementioned study conducted by researchers in Colorado evaluated 24 males, half chronic marijuana users (at least weekly use) and half having abstained from marijuana for the last year. The study found no difference between the groups pulmonary function (assessed with FEV1), cardiovascular function (assessed with VO2 max), muscle endurance (assessed with planks and grip strength) or anaerobic performance (assessed with peak power output). However, there was a trend towards decreased power output in the marijuana users, which may be significant in a larger cohort. The study did find that chronic marijuana users had higher blood levels of CRP (C-reactive protein), a marker of inflammation.

So what does this mean? Despite some athletes having the impression that marijuana can increase athletic performance, this is unlikely. If anything, these results suggest that marijuana may decrease power output, and would therefore not be recommended for athletes in sports were power output is important such as weightlifting. Caution should be utilized in interpreting the results of this relatively small study, further research will be necessary to get a more definitive picture of marijuana’s affect on athletic performance.

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