Kien V. Trinh, Dion Diep, Hannah Robson
Clinical Journal of Sport Medicine, Volume 28, No. 4, July 2018
Currently, many sporting organizations including the International Olympic Committee (IOC) prohibit the use of any substance that has an ergogenic (performance enhancing) effect, poses a risk to the use of the user’s health and safety, or violates the spirit of sport. The legalization of marijuana in Canada is tentatively set for October 2018, which may increase the use and normalization of the drug. Thus, it is vital that primary care physicians remain up to date regarding the rules and regulations surrounding marijuana use, as well as its effects on users. Much of the literature points to marijuana being more of an ergolytic drug, where it impairs rather than improves one’s physical performance, stamina, or recovery. Despite patient beliefs that that marijuana use can improve their performance, it’s ergogenic potential remains poorly understood. The purpose of this study was to determine the effects of marijuana on athletic performance.
This systematic review included any primary study of any design of any clinically or laboratory-relevant outcomes on athletic performance. Studies included both male and female participants of any athletic background, between the ages of 18 and 65 with no other comorbid conditions. All studies used marijuana cigarettes for the intervention group and all studies utilized a control group (participants that were not given marijuana cigarettes). Vital signs, pulmonary measures, physical work capacity, grip strength, and exercise duration were chosen to be relevant outcomes. After identifying and screening 929 citation postings, only 3 trials met the inclusion criteria.
The effects of marijuana on heart rate, blood pressure and exercise duration remains unclear. Low-quality evidence exists for marijuana having an ergogenic on effect on exercise by inducing bronchodilation and increasing FEV1 after exercise compared to inactive controls. There was no significant difference in grip strength between treatment, sham and inactive control groups. Additionally, there is low-quality evidence that suggests marijuana use is associated with decreased physical work capacity compared with sham and inactive control groups.
There are several limitations to this study. Firstly, there were only 3 trials (one observational, one crossover, and one crossover randomized control trial) that met the inclusion criteria. When comparing these 3 trials, clear heterogeneity is noted between study type, intervention, and outcomes. Thus, no meta-analyses were performed. Furthermore, despite various available forms of consumption (e.g. edible, vaporization, tinctures, oils), all studies only assessed smoked marijuana as their treatment. There is a clear paucity of current research on marijuana and its effects on athletic performance. The banning of substances in competition is a highly debated and ever-changing field. With its legalization in Canada looming, further research is warranted on marijuana and its effect on athletic performance to help investigate and justify current and future doping policy.
Sean Mindra, MD, CCFP
PGY3 – Sport and Exercise Medicine, University of Ottawa
Advisor: Dr. Taryn Taylor BKin, MSc, MD, CCFP (SEM), Dip Sport & Exercise Medicine