Outside, it’s a few degrees south of zero. But inside this CrossFit gym in Grand Forks, N.D., a half-dozen fitness nuts–three men, three women–are just warming up. Tom Harmon, a former Army reservist who runs this 5,300-sq.-ft. space in a mall, is about to put his troops through the workout of the day: five dead lifts, raising a barbell from the floor to hip level; then seven burpees, a CrossFit favorite in which you hit the floor from a standing position, do a push-up, then jump in the air, repeat and rinse; then nine wall ball shots, tossing a medicine ball above a marked spot on the wall. The goal: repeat this exercise cycle as many times as possible in 12 minutes.
Harmon cranks up the music. “Ten seconds on the clock, guys,” he says. “Three, two, one and go.” The CrossFitters gamely start grinding. Harmon–who opened this location, one of two CrossFit outposts in Grand Forks (pop. 53,000), about two years ago–estimates that about 50% of his clients quit after three months. “There’s a big commitment level to this,” he says. “People get weeded out pretty quick.” About five minutes in, the burpees get slower, the breaths heavier. “Blane, squat,” Harmon says. “Nope, get lower. There you go, bud. Good job, bud.” The wall clock is inching toward 12 minutes. “One minute, guys, one more,” says Harmon. “Push through this.” Time. One guy paces around. The other five participants are splayed on the floor. They give each other air-fives from their backs.
CrossFit is what happens when our need to exercise slams into our need for instant gratification. Marathons, triathlons and Tough Mudder events deliver the requisite torture but require lots of training time. Particularly after the holidays, we want chiseled abs and sculpted triceps and a clearer head right now. We’re too busy to futz around at the dumbbell rack or run 80 lonely miles a week. And after spending all day tethered to our devices, we’re itching to talk to other humans at the gym. Shared suffering, it turns out, is a powerful urge.
People are flocking to CrossFit and other extreme exercise programs; the potential physical and social benefits are undeniable. But as hyperintensive exercise programs increase their reach, more health professionals are raising serious concerns. Lifting heavy weights until you’re fatigued can be dangerous, especially if you haven’t mastered the proper technique. Lose sight of your physical limits and you can wind up in the ER. “The overarching question is, Do people need to do this, at such high intensity, repeatedly to failure?” says Michael Bergeron, a professor at the University of South Dakota’s Sanford School of Medicine and the executive director of the National Institute for Athletic Health & Performance. “Most people don’t need to train like that to enhance their health, to look good, to be fit.”
CrossFit isn’t backing down one rep. “If the criticism is ‘Your culture is too aggressive, too abrasive and offensive,’ yeah, that may be true,” says CrossFit social-media guru and spokesman Russell Berger. “They may have us on that one.” The company even embraces its critics: one of the company’s cartoon mascots is Pukie, a vomiting clown.
More Reps, More Often
There is no doubt that CrossFit’s high-intensity ethos is exploding. At the end of 2012, there were about 5,000 CrossFit gyms, or boxes, as they are known in CrossFit lingo. A year later, CrossFit had more than 8,000 affiliates worldwide. The company expects to pass 10,000 this year. Revenues were projected to double, to $100 million, over the past year. In 2011, some 26,000 people tried to qualify for the annual CrossFit Games, held in Carson, Calif., which crown the “Fittest on Earth.” Last year 138,000 people registered to compete. The games are sponsored by Reebok and broadcast on ESPN. “I am impressed with how CrossFit has fostered a small-tribe mentality,” says John Ratey, a professor of psychiatry at Harvard University and the author of Spark: The Revolutionary New Science of Exercise and the Brain. “Anything that creates real human interaction is a big plus for civilization.”
CrossFit grew out of one particularly intense tribe when Greg Glassman, a former gymnast who had been training local police in Santa Cruz, Calif., realized that his training methods worked for cops, couch potatoes and Olympic-level athletes alike. The approach is simple: instead of concentrating on cardio on the treadmill or pumping one muscle group, CrossFit mixes pull-ups, burpees, the rowing machine and other activities. You work more muscles, more often and faster. “You have to pick something off the floor–dead lift,” says Kyle Smith, a CrossFit trainer in New York City. “You have to put something up on the shelf–shoulder press. These are all movements in our daily lives that we want to do better in the gym.”
Glassman, now 57, paired his unyielding approach to exercise with a simple business model. Boxes aren’t franchises subject to excessive control from headquarters or state franchise laws. They’re independent affiliates: essentially, owners can take a weekend Level 1 certification course for $1,000, pass a test and then apply to open a CrossFit box. If CrossFit signs off, the annual fee is now $3,000. The local gyms keep all revenue; in general, CrossFit membership goes for $125 to $200 a month. “You’re in charge,” Glassman said in a 2012 interview posted on CrossFit.com. “Remove everything between you and your success that isn’t essential. I mean, that’s a beautiful thing.”
When done correctly, CrossFit training works. In a November study published in the Journal of Strength and Conditioning Research, exercise scientists from Ohio State University measured the body-fat percentage and aerobic endurance of 43 subjects before and after they completed an intensive, 10-week CrossFit program. The results: body fat significantly decreased and endurance significantly increased for both men and women across all levels of prior workout experience and body composition.
Catherine Yeager, 42, a psychologist from Grand Forks, has lost 30 lb. since starting CrossFit in June 2012. “Before that, I’d run the treadmill and do some random weight lifting, and I started to feel like I wanted to cry, it was so boring,” says Yeager, who has no real athletic background. She used to concoct reasons to sit out PE. Now she can do handstand push-ups.
Boxes are social but rarely mimic the pickup scene of generic gyms. “It’s scary for women to try to lift weights in a regular gym,” says Jessica Singer, an economics Ph.D. student, after a workout at a New York City CrossFit box. “It’s such a culture of macho men.” Singer, who has 10 years of experience as a dancer, has been going to CrossFit for four months. “I didn’t think I’d like the social aspect,” she says. “You’re all sweaty–it’s just not fun. But it’s nice to have people egg you on. I wouldn’t push myself as much alone as I do here.”
But all that egging on has invited questions about CrossFit’s safety. After an intense eight-minute warm-up, Jenifer Green, 35, took a break about four minutes into an early-November workout. “My arms felt like spaghetti,” says Green, who owns a supplement company in Pottstown, Pa. The burpees and wall balls were too much.
A pair of trainers didn’t look pleased. Come on, you’re better than that, they told Green. Keep pushing. After a few minutes, she resumed churning on the rowing machine, followed by box jumps, push-ups, medicine-ball lifts and runs around the building.
Green felt more dehydrated than usual when she left that night. Over the next week, her arms, which she could barely move, started to swell. Brushing her teeth or washing her face caused crushing pain. “I would have rather given birth,” says Green, a mother of three.
A few days later, “my arms looked like Robin Williams’ in Popeye,” Green says. “My feet looked like footballs. My toes were like Vienna sausages.” She reached the emergency room just in time; doctors diagnosed her with exertional rhabdomyolysis, a potentially fatal condition in which muscle fibers break down from overexercise, leading to the release of a protein, myoglobin, into the bloodstream. Too much myoglobin can damage the kidneys. Green was prescribed 30 days of bed rest and urged to drink vats of water.
Two months later, Green takes responsibility for her rhabdo; her competitive urges took over. She even plans on returning to CrossFit. But she doesn’t absolve CrossFit either. “That in-your-face, keep-going mentality–sometimes you wonder, Are you serious?” says Green, who defied her doctor’s orders and returned to work a week after leaving the hospital. “But that’s the extremist CrossFit culture.”
The company says it doesn’t teach trainers to push people past their limits. Trainers are made fully aware of the risks of rhabdo and given tips on how to prevent it. CrossFit has even adopted another cartoon mascot: Uncle Rhabdo, an exhausted, bloodied clown attached to a dialysis machine, with a kidney and his large intestine lying on the floor. “People look at that, and they get offended and say, ‘You guys aren’t taking this seriously,'” says Berger. “And the whole point–it’s supposed to get people’s attention. The last thing we want is somebody who’s uneducated or unaware of this condition giving themselves a serious case of it.”
In September, Eric Robertson, a professor of physical therapy at Regis University in Denver, posted an article about rhabdo on Medium.com, headlined CrossFit’s dirty little secret. Robertson wrote, “Rhabdomyolysis isn’t a common condition, yet it’s so commonly encountered in CrossFit that they have a cartoon about it.” CrossFitters jumped all over him; he shut down his Facebook account. “It was everything from You’re a troll, you’re an idiot, you don’t know what you’re talking about,” Robertson says. “It was nasty all the way through.”
On Twitter, Berger called Robertson’s article a “dishonest hit piece” and badgered Robertson to publicly debate him. After Good Morning America interviewed Robertson for a segment on rhabdo, someone made a spoof of it titled “CrossFit Threatens America.” With Robertson onscreen, a voice dubbed over his actual comments. “With exercise comes risk,” it said. “That’s why I’ve never exercised once in my life.” The narrator belittles an actual rhabdo victim shown onscreen. CrossFit sent out the spoof from its Twitter feed.
Some doctors and physical therapists are reporting plenty of other CrossFit injuries. Joe Terry, a physical therapist in Peoria, Ill., has seen a steady stream of CrossFit-induced ailments ranging from knee and pelvic pain to herniated disks to lumbar stress fractures, which cause severe lower-back pain. Buyer beware, says Terry. Make sure your trainer is well versed in proper weight-lifting form. “Certain gyms tend to have healthier clients than others,” says Terry. “Make educated decisions. Don’t be more concerned about beating your time or increasing your rounds than listening to your body.”
The scientific evidence is inconclusive. One study, to be published in the Journal of Strength and Conditioning Research, surveyed CrossFitters across global online forums: 97 of the 132 respondents, or 73.5%, said they suffered an injury that prevented them from “working, training or competing.” Nine, or 7%, said their injuries required surgery. The average period of CrossFit training was 18.6 months; no rhabdo cases were reported. The authors conclude that CrossFit has injury rates broadly similar to those of activities like Olympic weight lifting, power lifting, gymnastics, distance running and triathlon training, but they also acknowledge the study’s potential self-selection bias, “with athletes who have had an injury being more likely to participate.”
Yet Yuri Feito, an exercise-science professor at Kennesaw State University in Georgia, has compiled data that have yet to be published or peer-reviewed that found that although half of his 733 respondents suffered some kind of CrossFit injury, 85% of the injuries were mild– things like abrasions and minor sprains. “That surprised me,” says Feito. “I was expecting to see some more severe injuries, given the nature of the program.” Feito found three cases of rhabdo.
Berger won’t apologize for CrossFit’s tactics. Scientists like Robertson, who Berger feels are slandering CrossFit, may want to seek cover. “We’re going to be direct, and we’re going to carry a big stick,” Berger says. “He should feel bullied.” A few days later, Berger wants to amend his words. Bullied is too strong. “They should feel pressure,” Berger says. “People who are unwilling to engage intellectually to try to figure out what the truth is, I think they are going to feel that pressure.”
Of course, CrossFit isn’t the only hyperintense exercise program out there. The Insanity workout, P90X and obstacle-course runs like Tough Mudder and Spartan Race have devoted followings. And you can still look good–and feel good–while doing more traditional dieting and runs around the neighborhood. All these newer exercise routines share benefactors: Facebook, Twitter and other social-media sites. You know, the bragging machines. On a recent morning, a sarcastic tweet captured the oversharing habit: “I wish people who did CrossFit were more open about it.”
Nat DeWolf, an actor from New York City, understands that sentiment. “I’m doing things I never thought I’d be able to do,” DeWolf, 49, says. His arthritis has subsided. Mentally, he’s in good shape. “I’ve posted about it twice on Facebook, and it’s taken such restraint not to do it more,” says DeWolf, who’s been doing CrossFit for more than a year. He remembers irritant friends bugging him to do CrossFit. Now he’s the irritant. “I’m them,” DeWolf says. “It’s horrifying.”
CrossFitters admit they can get a little evangelical about their obsession. Says Joshua Newman, a co-owner of CrossFit NYC: “Are we the Jehovah’s Witnesses of exercise? Sure, that’s a fair tag. But there’s a difference. Jehovah’s Witnesses ring your doorbell and proclaim the good news. With CrossFit, it’s more like Invasion of the Body Snatchers. ‘You used to be my friend. Now all you want to do is talk about your dead lift. What has gotten into you?'”
This appears in the January 20, 2014 issue of TIME.