Update: A viral study previously mentioned in this article about CrossFit's injury rate included dubious data, and the journal wound up retracting the study in 2017 because of ethical breeches. We've updated the article to reflect that.
Sweating, screaming, pumping, pushing: It's no secret that CrossFit is an extreme form of exercise. A combination of rapid-fire bodybuilding, gymnastics, and track-and-field moves, the workout has attracted a global following. Celebrities like Cameron Diaz and Jessica Alba have helped it along, swearing it's a sure way to a hard body.
Alongside the acolytes, though, there are critics: Among them are the folks who find the pistol prizes at the upcoming 2016 CrossFit Games objectionable. (And yes, CrossFit is really awarding Glocks to the winners of their fitness competition.) Still others say they have been badly injured by the demanding exercise regime.
Numerous studies have looked at the health effects of CrossFit, with evidence of pretty immodest injuries. But is CrossFit really more dangerous than other workouts? Let's walk through what we know.
Beware of retinal detachment
A 2013 edition of Case Reports in Ophthalmological Medicine outlined a nasty cautionary tale: A 25-year-old patient presented with a detached retina. The cause? He had been using an elastic resistance band during CrossFit training, and the plastic snapped back in his eye.
The patient's retina was successfully reattached, but the doctors warned that CrossFitters and other gym-goers who use resistance bands should consider wearing protective eye gear or, at least, regularly replacing worn bands to avoid damaging more healthy eyeballs.
Your muscles could break down ... to the point of death
In an article in CrossFit Journal (which is not peer reviewed) Greg Glassman, the founder of CrossFit, discusses what he calls more evidence of the workout's "potency": rhabdomyolysis. It's a condition that's brought on when you work out so hard, your muscle fibers break down and release their cells into your bloodstream, leading to kidney failure and even death.
At the time of publication, in 2005, five CrossFitters had been hospitalized as a result of this rapid muscle meltdown. Glassman concluded that the victims were exposed to "too much work in too short a time." In his view, however, this was a good thing: evidence of "the utter and complete absence of challengers to CrossFit workout performances."
Men get injured more
For this study, published in April in the Orthopaedic Journal of Sports Medicine, researchers sent out an electronic survey to CrossFit gyms in Rochester, New York City and Philadelphia and through the main CrossFit website. People who were participating in CrossFit in the US were allowed to respond. CrossFit men reported sustaining more injuries than women. "Interestingly, females were more likely to seek help from a trainer, and therefore, this may account for their decreased injury rate," the study reads.
Overall, shoulder and low back injuries were most common, followed by knee injuries.
You might pee your pants
It's no secret that Pukey the CrossFit clown visits its adherents after an intense workout. That's right: CrossFitters embrace the "no pain, no gain" mentality to the point of vomiting. But, apparently, losing control of your bladder is not uncommon, either. In this video Rory McKernan, host of the CrossFit Games, investigated what he called "EIUL." That stands for "exercise induced urinary leakage."
Surveying a bunch of CrossFitters, he discovered that leaving a puddle behind after your workout is another widely embraced side-effect. The cause? According to his interview subjects, "double unders," or very fast rope skipping. "I do about ten double-unders and I'm standing in a puddle," said one devotee, who also happened to be a gynecologist. "It ain't pretty."
McKernan seemed amused. It's not all fun and pee, though. This man filed a lawsuit against a CrossFit affiliate, alleging that the workout caused him to pee until he bled and that he was never the same again.
CrossFit isn't more dangerous than other similar sports
These studies revealed real CrossFit harms, but is the workout really more dangerous than any other?
Despite its reputation, the injury rate at CrossFit looks a lot like other similar workouts, such as powerlifting or gymnastics. That's probably about right given that CrossFit routines involve dead-lifting, rope skipping, burpees, and other exercises common to power-lifting or gymnastics.
It's also important to note that all of these studies had small samples sizes, which aren't necessarily representative of the broader CrossFit experience. Self-reporting isn't the most reliable form of data, and those who were injured during CrossFit may have been more likely to respond to the surveys about injury than those who have had only positive experiences.
But besides science, there's also common sense. Any intense exercise comes with the risk of injury — perhaps especially one that has Pukey as its mascot. And if you dive into CrossFit after not working out for a while, you're probably particularly prone to breaking something or worse. Even the CrossFit founder acknowledges—and celebrates—this. "It can kill you," he once told the New York Times. "I've always been completely honest about that." Whether he likes it or not, the science only seems to back him up.