Marijuana and Lifting Weights: What the Science Suggests

There are currently twenty nine states that have legalized marijuana, or cannabis use in some form, whether it be medically or recreationally. Of these twenty nine, eight states have legalized marijuana for recreational use.

In 2016, it was reported that the number of adults who say they regularly use marijuana has doubled since 2013. Gallup News illustrated this stat in their 2016 survey that showed 13% of adults admitting to regular marijuana use.

The use of marijuana — or at least the discussion surrounding it — is becoming less of a taboo topic across the U.S. We’re seeing states become much more liberal with how they view the use of cannabis. In addition, we’re seeing more athletes admitting to anecdotally using marijuana to improve performance, support recovery, and even help consume their goal calories.

Unfortunately, there haven’t been a ton of studies done on cannabis and its direct effects on exercise. This is partly due to how the drug is still listed as an illegal substance in many states, so funding and studies become increasingly more tough to perform. Although there have been a few studies that have provided some insight into cannabis/THC’s effects on sport performance.

Cannabis and Sport Performance

Many study have addressed that there hasn’t been enough research to claim any performance enhancing effects cannabis may have. In fact, of the few studies done, they usually result in slightly decreased performance, or no effect whatsoever. For example, this older study from 1986 looked at marijuana’s effects on subjects who performed maximal exercise testing to exhaustion on an ergocycle. Researchers had 12-healthy individuals split into two groups: Non-smoking, then a group that performed 10-minutes after smoking a marijuana cigarette.

Researchers found that the group who smoked the marijuana cigarette experienced a slight decrease in performance duration. The marijuana group had a cumulative performance time of 15-minute, while the non-smoking group had 16-minutes. But at peak performance, researchers found no significant differences between the VO2 (oxygen uptake), VCO2 (carbon dioxide output), heart rate, and VE (minute ventilation).

Possibly the best review published on the topic of cannabis and sports performance was released in September 2017. This review analyzed 15 studies published.

In terms of strength, one study from 1979 had six males ages 21-27 partake in a sub-maximal biking and grip strength test. They were split into two groups: THC and placebo. The authors found that there was no effect on a subject’s grip strength, but there was a slight decrease in peak work capacity.

Another study that looked at THC and strength was performed in 1968. This study looked at 16 males aged 21-44. They performed 6-10 minute bouts on the treadmill and finger ergograph (a tool to assess a muscle’s work output). The authors didn’t publish the finger ergograph’s results, but noted within their study that, “Weakness was clearly demonstrated on the finger ergograph”.

The final study worth mentioning from the review followed 10-healthy males who were split into a control group and THC cigarette group. Subjects performed a bicycle ergometer test that started at 150 kg/min and increased by 150 kg/min on 5 min intervals until exhaustion.

Researchers recorded multiple attributes including heart rate, VO2, VCO2, blood pressure, tidal volume, and a few other factors. The authors noted that the THC group all had their total work output decreased in comparison to the control group (who averaged 29.9-minutes), and one subject in the THC group became “stoned” and dropped out at 9.9 minutes.

Takeaways

Of the studies and reviews analyzed for this article, we couldn’t find one that conclusively suggested cannabis could be a performance enhancing drug. In fact, from what we analyzed, there was a consistent slight decrease in a subject’s total work output from the use of cannabis. Yet, it’s still nearly impossible to make any definitive claims on cannabis’s impacts on strength training and sport performance for a few reasons.

First, all of the studies were slightly older, so their methods for conducting research may differ from what researchers may currently use. Second, all of the studies had VERY small populations, which could create a bias in their results. Thirdly, none of the studies compared cannabis use with strength training programs. Fourth and lastly, of the studies in the review, none of them looked at a prolonged use of cannabis and strength training.

The use of cannabis in 41 states is still listed as illegal for recreational use. For athletes who regularly partake in tested strength sports and use marijuana regularly, then they should take the WADA’s thresholds into special consideration. It’s difficult to definitely say what marijuana will do to strength training and sports performance due to limited research.

In the future, we hope to see more studies done on the impact of marijuana use on strength training.