Dedicated runners, like climbers, cultists and fanatics of any inclination, will pursue a trend or perceived advantage in their chosen avocation to a relentless degree – sometimes even into a haze of marijuana smoke.

Chasing that edge, some marathon runners – and their possibly masochistic comrades, ultramarathon runners – have taken up marijuana, as the Wall Street Journal recently documented. For years, runners have debated the benefits and drawbacks of cannabis on their performance and recovery, albeit without much scientific input and with a great deal of “asking for a friend”.

The runners who espouse marijuana say it decreases stress, cramps and nausea during a run, and say it acts as a relaxant afterward for managing pain and sore muscles.

Dr Donald Tashkin of the University of California, Los Angeles, who studies how marijuana affects the lungs, said that his research simply showed it “didn’t have an effect on impairing lung function”.

But marijuana “does have an effect of symptoms of chronic bronchitis”, Tashkin said, including “cough and sputum” that develop when smoke irritates the lungs. “There are other potential risks that have not been confirmed,” he added, such as a possible associations for pneumonia, particularly for people with compromised immune systems, since the psychoactive chemical THC found in cannabis suppresses the system. However, Tashkin was careful to note that so far not enough research supports one scenario or another.

Even “very heavy smokers” showed nothing like the effects of tobacco smoking, Tashkin said, who are disposed to both “devastating” chronic obstructive disease and lung cancer. For marijuana users, “neither of these risks seem applicable”, he said.

A 2012 study funded by the National Institutes of Health, in which Tashkin was not involved, found that exposure of up to seven “joint years” (ie 365 joints and/or pipe bowls) did not diminish lung function. That study actually found that marijuana users performed better on a lung function test – by a microscopic margin – than nonsmokers, possibly because of smokers’ “training” with deep breaths and holding smoke, the researchers said.

Tashkin stressed that so far there’s not enough research to draw definitive conclusions about marijuana’s effects, although there are areas of interest. In one unpublished study he worked on, researchers found that THC speeds up a person’s heart rate, “so that during exercise one can prematurely reach his maximal heart rate”. In this scenario, Tashkin said, THC increases the risk that a person could overtax their heart and lungs, “and that may actually then lead to cessation of exercise” due to overexertion.

But there should be no doubt that cannabis provides pain relief and relaxes the body, said Dr Donald Abrams, a professor of clinical medicine at the University of California, San Francisco, who has studied medical cannabis since 1996.

Abrams cited placebo studies with HIV patients who have suffered nerve pain from the virus and medications, and said the body has a system of cannabinoid receptors that help us modulate pain and the experience of it.

“I’ve been an oncologist for 32 years,” Abrams said. “I don’t need a placebo study to tell me that cannabis is useful as an analgesic and for treating nausea induced by chemotherapy.”

Different strains make big differences, he said, as it is the chemical CBD within marijuana, rather than the better-known THC, that acts as an anti-inflammatory agent. Most dispensaries sell blends, he said: “So for runners who are concerned about inflammation and pain, it would seem that the CBD-enriched strain is what they’re looking for.”

On the ethics of athletes in organized sports using the drug to push their bodies past natural limits, Abrams was circumspect: “Whether or not it’s appropriate for a person to trick their body while doing something that’s inducing pain and they maybe shouldn’t be doing, well, that’s a whole other question entirely.”

One organization that does concern itself with those ethics, the World Anti-Doping Agency, officially bans marijuana as a performance enhancing drug, but in 2013 it increased its accepted level of THC to an amount that would mean an athlete would not be disciplined unless he or she had ingested the drug the day of a test.

Marijuana as analgesic is not only a runner’s habit. Triathlete Clifford Drusinsky, snowboarder Ross Rebagliati and others say it relaxes them and improves focus. Other sporting associations and leagues, like the NFL, are also slowly increasing THC testing thresholds as more and more athletes admit using marijuana in a more accepting country. Former players Ricky Williams and Lomas Brown have estimated that as many as 40-50% of the league’s athletes consume cannabis for pain relief; the league is also struggling with prescription pill abuse.

In short, the arguments that marijuana can help manage pain or increase athletic performance are “plausible, scientifically”, said Dr Stefan Kertesz, an associate professor at the University of Alabama at Birmingham, who studies addiction and substance abuse. “But that doesn’t mean it’s proven,” he said, “and that situation leaves us at perpetual risk of underestimating the downsides of marijuana.”

Kertesz said that while it was “reassuring that there’s not significant long-term harm to lungs, there are effects for days, effects of slowed cognition, and even hints of long-lasting cognitive impairments on adolescents”. He said the growing use of marijuana by high-profile, elite athletes could make it seem more appealing and acceptable to teenagers, a group who research by the National Institute on Drug Abuse suggests are at higher risk of harmful effects.

“We’re not necessarily ready when the conversation about risk is as immature as it is,” Kertesz said, comparing the conversation around marijuana to that around alcohol. “So while alcohol is legal, adults and parents are much more adept at the conversation about drunk driving and adolescent alcohol use,” he said, than they are at talking about marijuana, a drug with a “substantive risk” of addiction and cognitive damage in adolescents.

“As a scientist or clinician, I can’t say what should be legal or illegal,” Kertesz concluded. “That’s society’s job to weigh the costs and benefits. But I can say there’s pretty strong research, and that as a father, I don’t want my son getting the message that, you know, elite athletes use it, so it might be OK with you too.”