Forget protein shakes. The newest workout supplement? Marijuana.

As marijuana legalization has pushed the drug further toward the mainstream — and a longstanding social stigma has begun to dissipate — more individuals are toking up before hitting the weight room, sports field, or mixed martial arts mat.

Sometimes dubbed “cannathletes,” those who regularly supplement a workout with some form of marijuana laud the benefits of the combination, claiming everything from improved focus and relaxation to help in recovery and pain management.

While the idea might seem inherently counterintuitive — weed, after all, is a substance more commonly paired with Doritos than dead lifts — there is a passionate contingent that swears by it.

“It’s a weird phenomenon, but it’s an increasingly common phenomenon,” says Peter Grinspoon, a primary care doctor at Massachusetts General Hospital and author of the book “Free Refills: A Doctor Confronts His Addiction.” “The fact that a lot of people are saying it helps them can’t be ignored.”

Signs of its influence are everywhere. In Boston and beyond, cannabis-themed yoga classes have become en vogue. On Reddit, users swap stories about their best (and worst) experiences working out under the influence. (“I toke up then go for a jog at night through the neighborhood,” writes one user. “It’s like a spirit journey.”)

Even the Massachusetts State Police gave a nod to the curious trend in a recent public service announcement.

“Working out high is legal,” read a tweet sent out by the department. “Driving is not.”

The union of sport and weed is not a new concept. In a famous scene from the 1977 documentary “Pumping Iron,” Arnold Schwarzenegger can be seen lounging on a sofa, joint in hand. And in a recent interview on a Bleacher Report podcast, former New England Patriots tight end Martellus Bennett estimated that — though it’s banned by the league — roughly 90 percent of current NFL players use marijuana, largely to deal with the physical pounding endured during the season.

What’s new, though, is the idea of working out while high.

“I call it a social movement,” says Jim McAlpine, the California-based founder of the 420 Games (the number is semiofficial code for pot), a multicity event that includes a 4.20-mile run and yoga class and invites participants to work out under the influence. “I’ll look on Instagram, and people define themselves as kind of ‘cannabis athletes.’ ”

Unlike traditional preworkout supplements — the caffeine and energy drinks designed to provide a jolt while exercising — cannabis has effects, say those who use it, that are largely psychological.

Proponents say that the drug gives them focus they otherwise can’t achieve, that it breaks up the monotony of a long run, or that it makes them more mentally nimble.

“When you’re high and training, it feels to me that options that might not necessarily be there when you’re sober might show up,” says a 28-year-old mixed martial artist from Saugus who asked to be identified by his nickname, Junior. “When I’m under the influence of cannabis and training, I find my game becomes more creative and less intentional.”

Cameron, from Boston, stumbled into the habit in college, when a friend suggested he smoke before a recreational soccer game and he found himself pleasantly surprised by the results —namely, how the typically grueling running suddenly didn’t seem so bad.

Today, it’s become such a part of his routine that rec soccer and basketball teammates sometimes jokingly check to make sure his eyes are bloodshot before games.

“Honestly, I think they are a little intrigued and amazed — like, ‘How are you doing this?’ ” he says. “But it’s what works for me.”

Tougher to determine is whether the perceived benefits have any scientific basis.

Research into marijuana’s benefits has been notoriously scant, due in large part to the drug’s federal classification as a Schedule 1 substance — meaning that, along with heroin, LSD, and ecstasy, it’s deemed to have “no currently accepted medical use and a high potential for abuse.” And the few studies that do exist offer relatively little insight into the drug’s effects during physical activity, beneficial or detrimental.

“The most critical finding from our review was that there are too few studies to draw any firm conclusions about the effects of cannabis on motor function,” said Shikha Prashad, a postdoctoral research scientist at the University of Texas Dallas’s Center for BrainHealth. Prashad coauthored a research review into cannabis’s effects on complex motor behaviors.

Indeed, even the most ardent spliff-and-lift advocates admit that the practice isn’t for everyone. Nor, they say, does it always go smoothly — particularly for the inexperienced. Junior remembers a competition in which he got too high beforehand — “by the second or third round I was just really, really, really high” — and was handily beaten.

“I do feel it’s really easy to fall into that lack-of-benefit zone,” says Junior, who says it took him years of trial and error before figuring out what amount best works for him. “It’s only useful when done correctly, and there’s a small window of correctness and a large window of error.”

At the same time, some insist, it’s a trend with staying power.

Eric Wilson, a personal trainer and owner of Movement Sciences in Boston, can envision a time in the next three to five years when there will be different cannabis oils or strains designed to enhance specific activities.

“If you’re going fishing, maybe you want an indica blend,” he says. “If you want to go for a long run, maybe a different one.”

In recent years, some advocates have called for professional sports leagues to allow marijuana use; former NBA commissioner David Stern said last year that medical marijuana should be removed from the league’s banned substances list.

The World Anti-Doping Agency, which provides oversight for athletic events ranging from the Olympics to the Boston Marathon, currently lists cannabinoids including marijuana as banned substances. And a spokesperson for the Boston Athletic Association said there are no plans to deviate from those rules.

Still, says McAlpine, “athletes for all of time have tried to find an edge to make them faster or stronger. And there will be people rushing to try this once they realize it’s not going to hurt them.”