It's one thing to marvel at the Olympic paragons of Gabby Douglas, Missy Franklin, or Usain Bolt. It's another to dive into a demanding physical regimen as if you're an athlete when you haven't been properly trained. But that may very well be happening as countless Americans take on high-intensity fitness programs like CrossFit, Insanity, or boot camps that push them to the brink of, or well past, their capacity.
Why the new fitness craze?
In part, it's a fast answer for a time-pressured population. But the trend also reflects the growing popularity of group fitness. "Not only are you part of a community, but also there's positive reinforcement. There's social support. Those are very important aspects of committing to an exercise regimen," says Alex Zimmerman, national manager for Equinox fitness clubs' master-level training program, Tier 4. Zimmerman also suspects the trend reflects a deep desire to slim down in a country with a weight problem. "As a nation, we're getting more and more desperate, and ultimately, people are looking more and more for a quick fix."
Research has shown that high-intensity interval training can burn 15 to 20 percent more calories than a moderate, steady workout of the same duration, explains Cedric Bryant, chief science officer for the American Council on Exercise. And since people cite time constraints as the primary reason for ditching a fitness program, a fast and furious workout provides an attractive solution, Bryant says. "This high-intensity approach basically allows you to get more for your time investment."
The problem, according to Bryant and other experts, is that these routines often ignore the critical role of "exercise progression," varying your workouts, as well as rest.
"A lot of times, it's too much, too soon," says William Kraemer, a professor of kinesiology, physiology, neurobiology, and medicine at the University of Connecticut. In fact, the demands of these uber-intense workout programs create physiological distress, raising adrenal stress levels and cortisol, a stress hormone that can dampen immunity, raising susceptibility to colds. "Even though [participants have] cut the weight and they can see their six-pack, it doesn't mean they're healthy," Kraemer says. But they may feel good. Along with providing a sense of accomplishment, these workouts prompt a "dramatic increase" in endorphins, he says, referring to the brain chemicals responsible for "runner's high."
The latest trend is just the most recent iteration of people physically pushing their limits—from heavy weight training in the mid-1800s to running and aerobics in the 1970s and 1980s, says Jan Todd, who, with her husband, Terry, codirects the Stark Center for Physical Culture and Sport at the University of Texas. But participation in today's trendy fitness programs can become obsessive and dangerous, they warn, noting the number of physical therapists they know whose businesses are booming due to CrossFit injuries. "I've heard [CrossFit] referred to as Scientology with dumbbells," which is "a bit on the mean side," Terry says, adding that the skepticism about the trend is understandable. "It's not an appropriate activity for an average person." Plus, CrossFit has an aspect of peer pressure, with the class cheering each other on "like you're the athlete," Jan says. That can create a "tendency to overpush yourself," when one should stop at the slightest sign of pain.
And that gets to another point: that striving for athletic acumen is not necessarily a prescription for health. In fact, a study published in the June issue of Mayo Clinic Proceedings found that "long-term, excessive endurance exercise," the kind involved in training for marathons, triathlons, or long-distance bike races, may actually harm cardiovascular health by hardening arteries. The article does note the well-documented fact that regular, daily exercise promotes a range of health benefits from promoting longevity to preventing disease.