Runners, high: Could cannabis before exercise encourage fitness?

Cannabis is generally associated with sedation and relaxation. In recent years, however, amateur and even professional athletes have been advocating for its use while exercising, write the authors of a recent paper in Sports Medicine. Given this — and increasing acceptance of its usage around the globe — there's an urgent need to properly investigate the impacts of cannabis on exercise, according to Laurel P Gibson at the University of Colorado Boulder, and colleagues. 

In their paper, the team describes the first study to explore the effects of commercially available cannabis products (i.e. with concentrations of active ingredients that are generally available to consumers) on how people felt about exercise in a lab environment. The nature of the research meant that the study had various limitations, but the results suggest that cannabis may indeed make work-outs more enjoyable some ways — though was also a drawback: the drug made exercise feel more effortful. 

The team studied 42 physically fit adults, all of whom exercised regularly and had previously used cannabis while running or jogging, with no negative effects. On two separate visits, each participants ran for 30 minutes on a treadmill; once without cannabis, and once after having used either 1 gram of a product that mostly contained THC (the main psychoactive ingredient of cannabis) or 1 gram of a CBD-based product (which mostly contained cannabidiol, with very little THC). 

The participants bought these doses from a local dispensary and were told to consume the product as they typically would (in a joint or pipe, for example) until they reached their own desired high. For legal reasons, the participants had to do this at home, with the team immediately taking a blood sample from them and droving them to the lab for the treadmill challenge. On average, the delay between using the cannabis and starting the exercise was only about half an hour. 

The researchers used results from earlier treadmill sessions to set individualised speeds and inclines, so that all the participants were exercising at about the same moderate-to-vigorous intensity. While they were jogging, they answered questions about their perceptions of the exercise. 

The team's analysis of the responses led them to some key insights. Firstly, cannabis made the exercise feel more enjoyable and put the participants in a better mood, especially in the CBD group. Both groups also reported feeling more of a 'runner's high' after using cannabis. 

However, cannabis (and particularly the THC product) also made them feel that they were working harder. This might have been because THC raises heart-rate, and earlier work has found that a faster heart rate during exercise makes people feel that they are exerting themselves more. 

The researchers acknowledge that the study has a number of potentially important limitations. The participants were far from representative of the general population, so the results may not generalise more broadly. Also, because they knew when they had used cannabis, how they felt while on the treadmill could have been affected by how they expected to feel. Even so, the team argues, this new work "marks an important first step in a nascent field." 

Other research has found that cannabis — and the ingredient THC, especially — can affect psychomotor skills, and lead to feelings of paranoia, anxiety, and tiredness, at least for some users. But if further work confirms that cannabis can make workouts feel more fun and shows that it can be safe for most people to use while exercising, the drug might potentially help people to get off the couch. Angela Bryan, one of the study's US-based authors, commented in a statement, "We have an epidemic of sedentary lifestyle in this country and we need new tools to try to get people to move their bodies in ways that are enjoyable. If cannabis is one of those tools, we need to explore it, keeping in mind both the harms and the benefits."

Read the paper in full.