You're almost finished a half-marathon. Pulse pounding in your ears. Knees aching. Running isn't for quitters.

But today is unusually easy: you're focused on the cool breeze on your arms, the golden late-September sun reflecting off the lake, and the ice-cold beer you're going to enjoy. Forget the chaos that's happening in your body.

Runner's high? Yes, totally. But the reason you feel so fantastic today is also due, at least in part, to the cannabis you consumed an hour before lacing up.

Forget the couch-locked stoner stereotype. With edibles and vaping making smoking an option rather than a must, weed's got an increasingly vocal fan base among athletes. And the growing population of runners, in particular, is openly touting herb as a training tool.

Wait, whaaat? Running on cannabis? Sounds counterintuitive to people who thinking getting and high and high-performance athletics are mutually exclusive activities. But from a brain chemistry perspective, marijuana and your workout match up like peanut butter and chocolate.

We've all heard of the "runner's high"— the euphoria that kicks in when you push your body hard, but not too hard. There's been surprisingly little research on why prolonged exercise feels so good—but studies by Andrea Giuffrida, an associate professor at the University of Texas Health Science Center, have shown a spike in naturally-occurring endocannabinoids in the bloodstream after high-intensity treadmill running.

These endocannabinoids work kind of like endorphins, increasing the body's pain threshold. Pot's anti-inflammatory, anti-nausea, boredom-killing effects also make it a natural fit for runners, who can often feel like they're going to simultaneously hurl their guts out and pass out from the tedium of 26+ miles on the road. In other words, doing a burn might help you ignore the burn, hit your goals, and keep on truckin'.

Everybody's doing it

With legalization sweeping the U.S., an increasing number of athletes are opening up about their marijuana use. A Colorado-based running group, Run on Grass, is dedicated to promoting running high.

The idea, according to the group's Facebook page is to "educate people about cannabis [...] while staying fit and having fun. We want to show that athletes of all shapes and sizes can support cannabis and the end of marijuana prohibition."

Run on Grass aren't the only ones who think marijuana can make pretty much any activity, including physical exercise, more fun. 22-year-old Avery Collins, who regularly runs for 17 to 20 hours straight as a professional ultra-marathoner, recently told the Wall Street Journal he consumes edibles, vapes, and rubs a cannabis-infused balm into his legs before runs - only, not before competitions, where the the drug is still banned. Other advocates include Team Hope in Texas , the The Cannabis Marathon Man, Canadian snowboarder Ross Rebagliati and mixed martial artist Nick Diaz, all of whom have publicly endorsed, ahem, elevated athletic activity.

No smoking

Obviously, the idea of inhaling smoke doesn't jive with most athletes. So how do you consume for maximum beneficial effect? Edibles, like marijuana energy bars, are the ingestion method of choice for some; others swear by Squibs, a powerful edible gummy that pack a 100mg punch of THC per unit.

If you're not lucky enough to live where edibles are legally sold, a few judicious hits from a vaporizer will also do the trick without roasting your lungs.

You can boost the calming, energizing effects of weed on your run by putting in a pair of headphones. There's a wealth of research to suggest that listening to music while running can improve your stamina and speed, and it stands to reason that combining that lift with your favourite, blood-pumping tunes could result in even better focus and performance.

However you consume—obviously, don't choose the big day of your first ultra-marathon to experiment. Better to test-drive the toke-and-train technique on a lazy, low-stakes Sunday 10K: you just might find it gives new meaning to the term "trailblazing."

h/t Scientific American, Mens Journal, Wall Street Journal