

Erin Beresini
is a freelance journalist covering endurance sports and health science. She has held various posts at ԹϺ over the years, including as an online staff writer and fitness editor, and is the author of . Her work has appeared in The New York Times, Men’s Journal, Atlas Obscura, and elsewhere. She lives in Los Angeles with her husband, two daughters, and one fur baby.
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Schools have been measuring kids’ fitness for decades, using now-controversial metrics like body mass index. California thinks there’s a better way.
Scientists have already created a device that reduces the energy cost of running and predict mainstream applications within four years.
It depends—but you can hold your breath longer in cold water
She won Olympic gold in a sport that chose her. Can she do the same in the one she truly loves?
The perfect summer day in this California beach town
Forget about counting reps in your head. This clever jump rope uses embedded LEDs to project that number in front of you.
American churches are building first-class gyms to get followers in shape and attract new members to the flock. Critics see lucrative businesses masked as ministries, but the programs are a spirited defense against our obesity epidemic.
How endurance athlete Patrick Sweeney puts away nearly 3,000 calories a day on the ketone diet
Two weeks of full-time, one-on-one instruction at Exos can set you back $4,800. Here’s how to get many of the same performance benefits without taking out a second mortgage.
On-the-go fitness tools for athletes
Goodbye crazy binges, hello almond butter?
An expert look at the most feasible—and nuttiest—submissions
A crude guideline for randy athletes
A compelling case for ditching hill repeats
Inside Specialized and Stanford University’s new alliance to research cycling’s effects on kids with ADHD
The suit, filed after 28-year-old Avishek Sengupta drowned at the 2013 Tough Mudder Mid-Atlantic event, had major implications for the obstacle-course-racing industry
The secret to unlocking your athletic potential is in your genes, but scientists don’t know what they’re telling us—yet
And why they’re more susceptible to diet trends
And when they'll be smashed—because half the fun of records is watching them fall
Inside the revolution to reclaim city waterways for recreation
Sorry, that wildly popular New York Times story is not for you
Secrets to lasting focus and motivation
A lawsuit reveals the personal spat that brought an end to the iconic endurance event
It’s got nothing to do with sailing
A new detergent called DeFUNKit promises to scrub stinky bacteria from synthetic workout apparel. We put the stuff to the test during a week of skiing, running, and traveling—and found we smelled as good on day seven as we did on day one.
Why Aussie athletes often turn to supplements when living high
Or why you should never, ever stop training
The somewhat simple answer to a popular question
What you need to know to start competing in the ultimate chill winter sport
Insider tips on conquering Aspen’s hottest event
Essential race-day, gear, and training intel
Champ Amby Burfoot and streak runner Ben Beach give the DL on the world’s most storied marathon
Everything you need to know about ultrarunning's ultimate gateway drug
Faves tweaked to optimize performance and recovery
The lowdown on the latest tech-enabled options
Unpacking the myths of winter fitness
4 strategies to help you quit worrying and learn to love the snow
The right moves make you faster and more resilient. Here's how to get the most important part of your training routine right.
Outsmart three winter-specific risks before, during, and after your workout
Promises to axe sugar, not flavor
The new genetic tool has the potential to increase resistance to muscular injury or stress fractures—even produce stronger, faster athletes—but it's a puzzle that could take decades to solve
The sport ends its most outrageous elements in a quest for longevity
A new study brings up two more glaring reasons to avoid hitting the wall in training
Inside the first ever Faith and Fitness Conference in New Orleans
Four performances that prove it
An effort by any other name won’t make you as great
Turns out the navigation devices routinely overestimate distance traveled. Why that quirk hasn't—and won't—affect cyclists.
And goes small
And how to put off being totally, utterly f*ed
The spirit of long-distance triathlons is being swallowed by behemoths like the World Triathlon Corporation. And it's our own fault.
Researchers say there is indeed too much of a good thing, and it’s killing your athletic potential
New research shows that while high-intensity movement is beneficial, nothing compares to the benefits of more movement
Oxygen seeks to show the beauty of female athleticism—and that women can be kick-ass athletes for life
It won't do you any good
Athletes competing for no country are not new to the Games, but a concentrated effort to recruit more of them could bring exciting new competition next year
The buzzword gives old tricks a new name
Do you really need the calories or just want them out of habit?
DNA testing service 23andMe is now FDA approved
You've probably been taught to run on soft surfaces whenever possible. Truth is, it doesn't make a difference.
In search of the everyman who will make bike commuting the norm
Cameras that shoot 360-degree footage could make virtual fitness classes a reality. But the tech’s not quite there yet.
Ultra coaches Eric Orton and Jason Koop on the importance of strength and speed over mileage
We like the price, but can this bra stand up to more expensive options from established sports brands? We put three models to the test to find out.
The so-called superfood is attempting a comeback, but don’t be fooled by its siren call
What the purchase by a Chinese billionaire means for the sport
We test three of the latest performance fuels in search of the ultimate podium snack
From extreme athlete Niccolo Porcella, the man who survived The Biggest Wipeout Ever
No, athletes aren't OD'ing on salt pills. But here's when you should lay off of them.
Columbia Sportswear announces it will pay two people a full six-month salary, plus benefits, to test gear around the world
Crush your next mountain adventure
A quick way to faster recovery and fewer injuries
A semi-scientific guide to sussing out the cheats
Have a blast while keeping your bike tire side down
A primer from overall winner of the Canadian Death Race, Alissa St. Laurent
Brought to you on film by running’s greatest bromantical couple
The trick is educating them with these honest, science-supported reasons why pets make our lives better
Once AT speed record attempt is complete
Exercises guaranteed to up your game, no matter your sport