"Are you CrossFit?"
Thirteen years have passed since Gregg Glassman founded CrossFit. In that time, over 6,100 affiliate gyms have opened, attracting thousands of professional and everyday athletes. What once was considered a fad has grown commonplace. Across the United States, thousands of gallons of sweat pour to the ground amidst struggled exhalations induced by intense workouts. It's masochism on a never-before-seen scale.
Yet despite CrossFit's meteoric rise, an ascent that has recently yielded prominent partnerships with Reebok and ESPN, there has yet to be a scientific study that specifically gauged its efficacy. Until now.
More on the study in a bit, but first, what is CrossFit?
For those unaware, CrossFit is an exercise program that blends strength and aerobic training into short, intense workouts. These workouts are often conducted once per day for three adjoining days, followed by one day of rest. In this respect, it's very similar to high-intensity interval training. But what sets CrossFit apart is both the exercises it recommends and the mindset it imparts. CrossFitters employ a varied blend of dynamic, functional weightlifting exercises that recruit multiple large muscle groups -- deadlifts, squats, snatches, and pull-ups, for example. At the same time, they eschew typical lifts like curls and those offered by weight machines.
"...these relatively worthless movements... have no functional analog in everyday life and... work only one joint at a time," Glassman argues (PDF).
CrossFitters combine these exercises into challenging workouts that often include speed and agility components as well. A typical CrossFit workout will recommend that the work be completed "for time." In other words, the exerciser should complete the lifts as fast as possible. That's where cardiovascular and competitive aspects enter. Most CrossFitters mightily struggle to set new personal records at every turn. Their workouts aren't simply means to a goal (such as losing weight); they are the goals.
Previous research has shown high intensity interval training to significantly improve cardiovascular fitness, blood pressure, and body fat after just ten weeks of a workout regimen composed of 25-minute workouts conducted three times per week. Does CrossFit take these results to the next level?
According to the new study, apparently so. Researchers at Ohio State University assigned 54 healthy participants to a five-day per week CrossFit-based exercise program that lasted ten weeks. The 43 participants that competed the program saw incredible improvements in measures of aerobic fitness and body composition. Maximum aerobic capacity grew by 13.6% for men and 11.8% for women. At the same time, male participants' body fat decreased from 22.2% to 18% and female participants' fell from 26.6% to 23.2%. Both men and women also enjoyed significant increases in lean muscle mass. What's more, the improvements in aerobic fitness and body composition were significant when broken down across participants' initial fitness levels. In other words, people of all shapes and sizes saw tremendous physical improvements.
But besides validating CrossFit's claims of amazing results, the study also substantiated one of its critics' key concerns. Of the eleven subjects who dropped out of the program, nine cited overuse or injury as the key motivator for their choice to discontinue. Moreover, the injuries occurred despite the fact that all of the workouts were supervised by certified professionals.
Of note, in May, CrossFit's Russell Berger questioned the validity of the high injury rates.
"The study does not define what it means by the term 'overuse,'" he wrote. "The study also does not detail what specific cases of 'overuse or injury' the subjects cited, what caused them, whether the cases were pre-existing conditions, or how long the subjects experienced 'overuse or injury.'"*
CrossFit is often a fiery program, pushing participants to the very limits. Repeated fatigue can attenuate muscular control and cause exercisers to revert to poor form, creating an atmosphere conducive to potentially debilitating overuse injuries. Moreover, overexertion is a real concern. CrossFit trainers regularly warn about the dangers of fatigue-fueled rhabdomyolysis, where muscle breaks down rapidly and enters the blood stream, a condition that can lead to kidney failure.
However, Glassman insists that CrossFit is "universally scalable," meaning that the intensity can be ratcheted down and the exercises simplified for any age and skill level. But the problem is that this is at odds with the CrossFit mindset, which encourages people to push themselves to the very limits. It can be difficult for everyday people to realize when to hold back.
Exercise physiologist Fabio Comana of the American Council on Exercise and San Diego State University insists that CrossFit trainers can occasionally push their students too far.
"I subscribe to the notion of teaching someone to paddle and float in the shallow end of the pool prior to pushing them to try to swim (or sink) in the deep end," he says.
All in all, as the new study makes clear, the purported results of CrossFit are very real, but the potential drawbacks are, too.
*Section added 8/20 to reflect CrossFit's response to this article
(Images: 1. Deadlift by Luis Javier Rodriguez via Wikimedia Commons 2. Smith et. al.)