Pretty much every elite endurance athlete trains in mountain air or the altitude-tent equivalent. But a few scientists think they're wasting their time and money.

With over 8,000 different "sustainable" hotel certifications, how do you know what's greenwashing and what's the real deal? We consulted experts to find out. 

Computers can identify sounds much better and faster than humans. So what do we learn when we ask them to listen to everything?

Before trying a fad diet, make sure you have all the information—and eat plenty of calories while you're at it

The United States leads the world in spending for health and fitness but still ranks lowest in measurements of actual health. How do we break the cycle?

After a long day on the slopes, your body deserves a little après of its own

Or why you don't have to get up at 4 A.M. to perform a two-hour ritual of self-care

There's at least a theoretical basis for believing in the power of CBD topicals

Launched by Specialized CEO Mike Sinyard, Project New Day promotes the use of hallucinogens like mushrooms to treat addiction and PTSD

The simple story of an unfair shoe with “springs” doesn’t capture the true complexity of the ongoing debate about technology in footwear

A new study finds unexpected benefits from super-short intervals with even shorter recoveries

Journaling is for everyone, but especially athletes. Here are the two types of journals you should have and how to get started.

Scientists are increasingly skeptical of the benefits of flexibility, but the fitness world doesn’t want to hear it

When Rebecca Mehra tried to unplug a broken oven, she almost ended her track season—or worse

Fluorinated glide wax is being banned from elite competitions, and big brands like Swix say they’re searching for environmentally friendly alternatives. But the seductively speedy—and noxious—compounds are unlikely to loosen their grip on the sport anytime soon.

New research hands down verdicts on what to lift, how much, and how hard

Six testers ran, climbed, hiked, and played outside with 17 different deodorants. Here's what didn't stink.

Personalized drinks and shakes are the latest innovation in the quest to boost performance

Italian students will soon be required to learn about global warming. American kids? Not so much.

Heat training has been hyped as a powerful workout enhancer, but new research sounds a note of caution

Anyone who disagrees is an "obvious idiot"

As we begin a critical new decade for the environment, we need to look toward the light

Researchers deploy machine learning to match running styles to the risk of different types of injury

To better push your limits, try swearing off some of your most familiar crutches now and then

Work hard, play hard—that's how many of us live today. But it turns out that our supercharged lives aren’t so great for us, and fitness experts and doctors are now emphasizing restorative practices and rest to improve performance and overall health.

17 surprisingly easy steps to a happier, less strung-out life—starting with your vagus nerve

Both substances are being studied for stress and anxiety relief. We asked the experts if and how they work.

Plenty of food trends from this year should stay in the past. And a few of them should come with you into 2020.

Why companies as diverse as Patagonia and General Mills are suddenly focused on getting dirty

Improving your max aerobic power may come at the cost of worse efficiency, a study finds

Ten books that sparked debate, started conversations, and launched movements in the past ten years—and what to read next

The experts have spoken on what we will see in the coming year

Up-to-date guidelines on the pros and cons of filters, ultraviolet light, chemicals, and other options

Snow science is a wild thing. And in the Sierra Nevada, it's a particular beast all its own.

A registered dietitian nutritionist could help you solve a mystery gut issue, boost your training, or develop a better relationship with food. Here's how to know what to look for.

To train athletes to truly push their limits, it helps to draw inspiration from the French social theorist Michel Foucault. Seriously.

A few tips to help you incorporate this​ lifelong hobby in​to your everyday excursions

Two new books take opposing views on one of the most contentious issues in sports

Great titles for the endurance-curious, or to curl up with yourself

There's no silver bullet, but these useful practices will help you keep training

Platelet-rich plasma therapy, or PRP, has been touted as a miracle cure for sports injuries, but it may counteract the benefits of plain old rehab exercises

A new analysis tracks people doing 35 hours of exercise per week for a decade, and finds no evidence of heart risks

A researcher thinks we may be able to recycle beer waste into a powerful algae-fighting tool

Whether you're looking for a sunny California odyssey or musings on the future of winter, we have a good book for you to curl up with in front of the fire

Scientists can forecast marathon performance fairly accurately. But for longer distances, things get complicated.

Be prepared to go into the backcountry with our expert knowledge, advice, and gear recommendations to stay safe

Biotech company Elysium Health just released an at-home DNA test that—supposedly—will tell you how well (or poorly) you're aging

All-out sprint speed may seem irrelevant in longer events, but new science is making the case for having a “speed reserve”

In his new book, 'Lifespan,' celebrated scientist David Sinclair lays out exactly why we age—and why he thinks we don't have to

How do we deal with the prospect of losing the places we love?

At a conference on sports innovation, sleep scientist Charles Samuels cuts through the hype

Backed by billionaire philanthropists and Silicon Valley venture capitalists, a wave of entrepreneurs are developing high-tech, low-cost technologies to probe the watery realms we still barely understand. Are the oceans finally getting their moon-shot moment?

A growing body of research shows that electric-assist bikes may have profoundly positive health impacts—and not just for the people who ride them but for society

The Lumos Matrix features turn signals, brake lights, and a customizable message panel. But by rallying around this "connected" helmet, are we surrendering to what it really represents?

The Swedish company Maurten's hydrogel drink has taken the endurance world by storm over the last two years. Now scientists are testing their claims.

Don't conflate fearlessness with bravery

Over the past decade, athletes, coaches, and researchers have been seduced by the performance-boosting promises of brain stimulation. On a ride-and-zap-your-brain-like-the-pros tour through the Alps, Alex Hutchinson wonders whether it really works—and whether we want it to.

Cody Townsend thought his project, the Fifty, would be a mission to descend the 50 best lines in North America. But then climate change started to melt the snow right out from under his skis.

Multimillionaire Victor Vescovo committed himself to one of the world’s craziest remaining adventure quests: to reach the deepest points in every ocean. What does it take to get there? A radically high-tech, $30 million Triton submersible, a team of crack engineers and scientists, and one very gonzo explorer.

Plants as criminal evidence and penguin sex lead the way in the latest batch of good reading material

The two-hour barrier and the women’s marathon world record both fell this weekend. The history makers, Eliud Kipchoge and Brigid Kosgei, have one obvious thing in common.

Nutrition science isn't perfect. Here's why.

Outdoor athletes have plenty of influence on Instagram. Protect Our Winters wants to wield it in the halls of Congress.

A new study quantifies the time gained and lost from the geography of the INEOS 1:59 Challenge course, and suggests that you don’t need to sweat the curves

Blood glucose monitoring for performance is becoming more common. Here's what you need to know.

Crunching the data suggests that distance runners at this year’s track world champs paced more aggressively than ever

Maybe not in our hearts, but certainly in our brains. Plus, they can make you love the indoors far too much—which is why there’s now a full-fledged, woodsy rehab center for joystick addicts who need a soothing pathway back to a normal life.

Delayed gratification gets harder when you’re overtrained, according to a new brain-scanning study

For years, the Oregon Project coach pushed the boundaries of what was allowed. Now, it has finally caught up to him.

New evidence bolsters the claim that adapting to hot weather gives an all-around fitness advantage—but not right away.

Reconstructing the history of civilization through beer labels

Some key takeaways on hydration, power meters, recovery, and menstrual period tracking

In her new book, ‘On Fire,’ Naomi Klein sparks a blaze for the next generation

Behind the headlines about the return of great whites to Cape Cod is a story about how we're learning to live alongside a terrifying predator

When your love for the outdoors meets chronic pain, you grieve—and then you adapt

Caffeine is old news on the supplement scene. These next-gen coffee products aim for additional benefits.

Staff members of Marie Stopes International navigate wild bulls, treacherous singletrack, and rushing rivers to make long-term birth control accessible to some of the hardest-to-access places in Nepal

The quality of your habits determines the quality of your life. Here's your step-by-step guide.