Highlights
- With the exception of CBD, cannabinoids remain prohibited by the Canadian Centre for Ethics in Sport during the competition phase of the athletic season and therefore are not to be used by athletes
- Although some cannabis and CBD products may be suggested to have the potential to aid with recovery or sports performance, very little, if any research exists to support these claims
- The risks of using CBD products to enhance performance or recovery largely outweigh the potential benefits, given the lack of evidence supporting their effectiveness, and the likelihood that these products may contain other banned cannabinoids
Every day, athletes are faced with small decisions that have potential to impact their performance, recovery and health. Often these decisions relate to things that may seem comparatively inconsequential to the average person, and can be as simple as what foods to eat, or what activities to avoid or participate in. When it comes to cannabis use, things are no different.
In October of 2018, recreational cannabis use became legal across all of Canada for individuals who are 19 years and older. Data gathered from the years following the legalization of recreational cannabis use suggest that one quarter of all Canadian adults, and nearly half of all Canadians aged 20-24, have used cannabis in the past year (Government of Canada, 2021). Clearly, cannabis use in Canada is widespread amongst the general population. But what should athletes be considering when it comes to using or avoiding cannabis?
In this article I will provide a research-informed exploration of the current state of cannabis use in relation to sport in Canada and provide advice for how sport organizations should approach the topic of cannabis with athletes.
Contextualizing cannabis
To start off, it’s important to understand what cannabis is. The term “cannabis” refers to a group of plant species containing unique molecules called “phytocannabinoids,” or more generally, “cannabinoids.” There are hundreds of different cannabinoid molecules, however, the 2 that most people will be familiar with are called delta-9-tetrahydrocannabinol (THC), and cannabidiol (CBD). THC is the primary cannabinoid responsible for causing the psychological effects of cannabis that many users are seeking. In other words, THC is responsible for the “high” that many people associate with cannabis use. CBD on the other hand, is generally not thought to cause psychological effects, since it interacts with chemical receptors in the body’s tissues in a different way than THC (Ahston, 2001). While many people tend to focus on the way each of these cannabinoids affect our brain, it’s important to understand that both may have effects on other tissues in our bodies. This is just one of the reasons that athletes should approach cannabis use cautiously.
While any adult in Canada older than 19 can legally use cannabis that contains THC or CBD recreationally, the picture is more complicated for athletes. Firstly, many sport organizations and regulatory bodies list cannabinoids as banned substances in some shape or form. For example, the World Anti-Doping Agency (WADA) bans the use of cannabinoids during the competition phases of the season (notably, CBD is exempt) (World Anti-Doping Agency, 2022). This is also relevant to Canadian athletes participating in U-SPORTS competitions, as these regulations are also enforced by U-SPORTS and the Canadian Centre for Ethics in Sport (Canadian Centre for Ethics in Sport, n.d.). Secondly, because cannabis has been illegal for a long time, research on the safety of cannabis use has been challenging to conduct in the general population (Haney, 2020) with even less work having been done with athletes (Burr et coll, 2021). Therefore, it is extremely important for athletes to understand that very little research exists surrounding many of the applications of cannabis in sport. For some athletes, each of these facts may be enough to deter from cannabis use, however, research suggests many athletes still use cannabis recreationally (National Collegiate Athletic Association, 2018; Peretti-Watel et coll, 2003), or even for performance enhancement (Lorente et coll, 2005).
Exploring reasons athletes use cannabis
Like many other people, athletes report using cannabis for reasons completely unrelated to sport, including recreational use. In 2018, a study conducted by the NCAA on its own student athletes reported that as many as 25% of athletes use cannabis recreationally (National Collegiate Athletic Association, 2018). In further support of this study, a systematic review of peer-reviewed literature identified similar lifetime and past-year prevalence of cannabis use in athletic populations from countries other than the USA (Docter et coll, 2020).
In Canada, the practice of recreational cannabis use is perfectly legal, assuming the athlete is 19 years or older, and the nature of use does not contradict substance use policies of sporting body regulating their respective sport. Nevertheless, recreational cannabis use, even outside of the competition phase of a season may still present significant risks to athletes. Many cannabinoids can be detected for up to days after the time of use and well after any effects have subsided, in biological samples (Huestis et coll, 1995). Therefore, it is entirely possible that cannabis use outside of, but in near proximity to competition, could trigger a violation. In an effort to avoid these situations, WADA tests numerous cannabinoids as “threshold substances” meaning that a certain level of cannabinoid has to be present in a sample, making it a little more lenient than a zero-tolerance style policy. However, despite the use of thresholds, cannabis related anti-doping violations are not uncommon in Canadian athletics (Canadian Centre for Ethics in Sport, n.d.).
Outside of recreational use, there is a growing body of evidence that some athletes use cannabis with the intention of improving performance. A survey of ultra-marathon runners showed that cannabinoids are one of the most widely utilized performance enhancing substances in the sport (Campian et coll, 2018). The prevailing thought for how cannabis may improve performance in this sport is that some of the reported effects of THC, such as reduced anxiety, nausea, and pain, may allow athletes to mitigate exercise related anxiety, pain, or exertion, and subsequently perform better.
To date, there is very little research studying cannabis use before exercise. The first studies found that patients with cardiovascular disease reached exhaustion sooner during an exercise test after using cannabis (Aronow & Cassidy, 1974, 1975) Studies in healthy individuals show similar but slightly different results. The first study using healthy participants showed that at a given heart rate, participants were not able to work as hard following cannabis use (Steadward & Singh, 1975). Based on this finding, authors concluded that maximal exercise performance would be reduced. A later study published on the topic that actually did examine maximal exercise after cannabis use showed that participants were unable to exercise for as long during an exercise test of increasing difficulty, providing direct evidence that cannabis did indeed negatively impact maximal exercise performance in healthy individuals (Renaud & Cormier, 1986).
While these studies provide some evidence that cannabis containing THC reduces exercise performance, there are a few caveats that should be considered. The primary caveat to all these studies is that none of these studies utilized exercise tests which mimic real-life athletic competitions, nor do they match the demands of the sports in which athletes most report use of cannabis for athletic performance enhancement. So, to fully understand how cannabis impacts performance, studies should aim to use more relevant exercise tests, particularly ones that mimic the demands of the sports from which athletes report cannabis use.
Additionally, the recreational cannabis available to athletes in today’s consumer market is much different from the cannabis available at the time of these early studies. Today, cannabis users have many more options for how they use cannabis. Although many people think of cannabis as something that is smoked or inhaled, modern day consumers can also eat or drink cannabis products. Recently, a study conducted at Colorado State University looked at the effects of edible cannabis products on numerous different cycling performance tests. Their results differ from the studies conducted 40-50 years ago, showing that cannabis had no effect on performance in the tests they used (Ewell et coll, 2022), nor did they affect the way the cardiovascular system responded to exercise. While all these studies provide valuable insight into how cannabis impacts performance, it should be acknowledged how many questions remain unanswered. For example, does the inhalation method matter? What if cannabis is used further out from when exercise begins? How about if we alter the cannabinoid composition within cannabis?
Each of these questions highlight the fact that right now, there is much more that is not known than is known about how cannabis impacts performance. While there is evidence that cannabis either negatively impacts, or does not impact performance, there is no empirical evidence to suggest that it has any benefits. Furthermore, very little research has systematically evaluated whether cannabis use prior to exercise threatens athlete safety or introduces any additional risk to health. This alone should be a good enough reason for athletes to avoid cannabis use before exercise. Given this, and the fact that cannabis use is banned in competition for many sports, athletes should avoid cannabis use with exercise. Even if cannabis could provide some benefits that outweigh these risks, there is very little existing evidence to suggest that cannabis used in conjunction with exercise should provide any kind of benefit. Athletes, coaches, and sporting bodies should keep a keen eye out for new research in this area that will hopefully emerge in coming years, and further inform our knowledge on how cannabis use impacts performance.
What the research says about CBD and exercise
While the use of whole cannabis within sport is relatively common, many will be aware that the use of CBD in sport is even more popular. In fact, informed choices surrounding CBD are arguably even more important to make, given that CBD is not a banned substance by WADA, and consequently, many sporting bodies. CBD has become an increasingly popular supplement for recovery and performance due to a range of claims including anti-inflammation, antioxidant properties, sleep promotion and pain relief (Gamelin et coll, 2020; Rojas-Valverde, 2021). The prevailing thought is that many of these effects would be beneficial for recovery from intense exercise or activities that are physically demanding on our bodies’ tissues.
While this thought may appear intuitive at the surface, there are many caveats regarding what research exists to support use of CBD by athletes, and whether these effects would be beneficial for athletes. Let’s first address arguably the most prominent claim for CBD, which is that its anti-inflammatory properties are beneficial for recovery. A popular method of testing how well something aids recovery in a research lab is by testing how well athletic performance can be preserved by a given intervention, following some sort of demanding exercise that results in some degree of muscle damage. In other words, studies will often have participants complete an exercise bout, and then measure either tissue damage, or performance in a subsequent bout with and without the intervention (in this case, CBD).
To date, there have been 3 studies (Cochrane-Snyman et coll, 2021; Crossland et coll, 2022; Isenmann et coll, 2021) with human participants which examine whether CBD is effective in mitigating muscle damage and performance decrements associated with resistance exercise. These studies have shown mixed but largely disappointing results. One of these studies showed that CBD can reduce blood markers of inflammation and muscle damage following damaging exercise, and that CBD may have allowed participants to recover back-squat performance 72 hours post-exercise (Isenmann et coll, 2021). However, the 2 other studies examining how CBD might affect muscle damage and fatigue showed that CBD performed no different than placebo, in any measure, performance- or inflammation-related (Cochrane-Snyman et coll, 2021; Crossland et coll, 2022).
Therefore, these studies provide little evidence, if any, suggesting that any potential anti-inflammatory effects of CBD are beneficial for recovery. It’s also important to note that the use of any anti-inflammatory drugs following training may not have intended effects, as studies have shown that inflammation may be important for adapting to training, and these types of products may blunt this response (Owens et coll, 2019). When it comes to pain mitigation following exercise, there is even less research. While there are no experimental laboratory studies assessing whether CBD alters the pain associated with exercise, a survey of rugby athletes demonstrated that although as many as 80% of athletes who used CBD did so with the intent of improving recovery or mitigating pain, only 14% perceived any benefit (Kasper et coll, 2020).
Research on the ability of CBD to improve sleep in athletes is about as equally scarce. Most of the research to date examining the effects of CBD on sleep have used clinical populations rather than athletes, with only one study reporting that CBD improved self-reported sleep onset and perceived quality (Carlini & Cunha, 1981). Another study in healthy participants showed no effects on subjective sleep quality, or objective measures of sleep quality following CBD use (Linares et coll, 2018).
While CBD has mainly been studied as a recovery aid for athletes, there is also potential that some of its purported effects related to benefitting pain and anxiety could create some utility for performance enhancement. To date, only one study has examined the acute effects of CBD on exercise performance, and the body’s response to exercise (Sahinovic et coll, 2022). A research group out of the University of Sydney asked participants to run both at a steady pace and at increasing speeds up to exhaustion after consuming CBD orally. The results of this study showed that despite small differences in the maximal amount of oxygen consumed and feelings of pleasure during exercise after CBD intake, time to exhaustion was not affected, suggesting that CBD does little to alter performance, and likely has only minor effects on the physiological and psychological responses to exercise.
When turning to the research, it doesn’t take long to realize that many of the claims tied to CBD use are largely unproven, and much work needs to be done before athletes should feel like using CBD is unequivocally a good idea. At the moment little evidence exists to suggest that CBD has any benefit for athletes at all, either when it comes to recovery, or performance. In addition to the lack of physiological benefits, CBD may possess its own anti-doping risks. Although CBD is not generally a banned substance, CBD products may actually contain THC, a banned substance. A growing body of research has identified that many cannabis products, including CBD products, are not accurately labelled (Johnson et coll, 2022; Vandrey et coll, 2015). Another analysis of 23 hemp products (a form of cannabis many CBD products are made from) showed that many of them contained a wide range of cannabinoids, with approximately 30% of them containing enough cannabinoids to cause an anti-doping rule violation if samples would have been taken within 8 hours of use (Mareck et coll, 2022).
Final thoughts
For athletes, coaches, and sporting bodies, the landscape of how to approach cannabis use in sport in 2023 remains uncertain. Since legalization of recreational use in Canada, athletes in the country have never had greater access to a range of products marketed for a vast array of claims that may seem attractive. That said, there remains significant gaps in the research that must be filled before cannabis or derivative cannabinoid products can be confidently recommended to any athlete seeking benefits from their use. Given the risks associated with product contamination, and potential unknowns about product safety, there is little reason to suggest that at the moment, any possible benefits of cannabinoid use in sport are outweighed by the current risks.
About the Author(s)
Christian Cheung is a member of the Human Performance and Health Research Laboratory at the University of Guelph, where he is currently completing his PhD in Human Health and Nutritional Sciences with a focus in cardiovascular and exercise physiology. Christian’s primary research efforts are dedicated to understanding how cannabis use impacts the cardiovascular system, with application to both cardiovascular health and human exercise performance.
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