For thousands of people across the country, going to a regular gym just doesn't cut it. Instead, they prefer CrossFit routines: like swinging kettlebells, flipping tires, and doing squats and dead lifts until they drop. Now kids as young as 4 are taking part.
The idea behind CrossFit Kids, says co-founder Jeff Martin, is to pair fitness and fun. Since he started the program with his wife Mikki in 2004, it has taken off. There are hundreds of CrossFit Kids classes across the U.S., and more in cities across the world.
When CrossFit DoneRight in Rockville, Md., opened classes for kids about two years ago, it was the first of its kind. Now, there are dozens in the D.C. area alone.
The owner, Justin Bacon, explains there are three classes for different age groups, one for 4- to 6-year-olds, another for 7- to 12-year-olds and another for teenagers.
The kids version isn't exactly like the adult classes. On a recent visit, it's a circuit of pushups, pullups and squats. A few months ago, the focus was on learning dead lifts and an Olympic lift known as "clean and jerk."
Owen Belamaric, 8, is not so sure about CrossFit. When I ask him what it is he doesn't like, he says, "the workout — it's always really hard!" Which raises the question, is it good to make the workout "hard" for kids?
That depends on your definition of "hard." In terms of weightlifting, the scientific opinion has changed in the past few years.
Jordon Metzl is a sports medicine physician at the Hospital for Special Surgery in New York City and author of The Athlete's Book of Home Remedies: 1,001 Doctor-Approved Health Fixes and Injury-Prevention Secrets for a Leaner, Fitter, More Athletic Body! Metzl says when people think about strength training for kids, the initial thought is, "Are you crazy? Kids should not be lifting weights." But he and many other sports medicine specialists are convinced that strength training can be great for kids.
That idea gained momentum in 2008, when the American Academy of Pediatrics revised its policy statement on weight training for children and adolescents. The AAP used to recommend against weightlifting, but after considering new research it determined it's safe for kids to start a light weightlifting routine after age 8. Metzl explains that kids who strength-train won't look like mini Schwarzeneggers — that type of bulking up doesn't happen until after puberty.
"The muscles don't look better, they just act actually a lot stronger, and it is very helpful for them," Metzl says.
Some of the kids do say they feel stronger. Nicole Doria-Rose brings her two sons to the CrossFit DoneRight class in Maryland on Saturdays.
"The little one likes it because he feels like he's getting stronger. I asked him in the grocery store to help carry some bags the other day, and he said, 'Oh, I can do this, and I do CrossFit,' " she says. At first Doria-Rose was skeptical about weightlifting for kids.
"I've read about kids, teenagers starting weightlifting too young and getting hurt because ... their bodies aren't mature enough to handle it, but at this level they're doing just a little bit of the weightlifting, and they're really teaching them how to do it properly," she says.
The problem is that some kids push themselves more than they should, which means proper form can be compromised. Last month, 10-year-old Sean Cooper set a personal record with an 85-pound dead lift. That kind of exercise worries Dr. Tim Hewett, a former power lifter and director of the Sports Medicine Biodynamics Center at the University of Cincinnati. He says there is no evidence that CrossFit is good for adults, let alone for kids.
"The people who most use this type of training are people like military people, Navy SEALs, and we don't even have any data that's even highly effective in highly conditioned people like that," Hewett says.
He says some CrossFit trainers aren't teaching appropriate techniques for weightlifting, or are trying to supervise too many athletes at once. And that could be dangerous.
"What kids are attempting to do is Olympic lifts like a snatch or a clean and jerk, and they don't have the power to properly perform the exercise to bring it up to their shoulders and then bring it over their head. So they're grabbing this thing at their waist and they're trying to twist and turn their torso, which is putting their spine at significant risk with weights that are greater than they can handle."
The best way to train kids, according to both doctors, is with high repetition, lightweight training. Kids should be able to do eight to 15 reps of whatever weight with no problem. Metzl, who just launched a kids strength training education project called Home Strength Training for Young Athletes with the AAP, explains that for kids to reap the benefits of strength training, they don't need to push too hard.
"We're not looking for full muscle fatigue at all," Metzl says. "There have been a number of studies that compare high-repetition, lightweight training to lifting big weights for a short time to bulk up muscles, and surprisingly the strength benefits are almost equivalent between the two."
Of course, Hewett says, kids should be incorporating activity into their daily lives and that will keep them in shape.
"Doing things they like to do, getting out into the park, into the playground, playing relatively low-impact sports and doing that throughout their childhood and hopefully throughout their lifetime," Hewett says.
So, if your kid wants to do CrossFit and the class has good trainers, that's just fine. But if your kid prefers doing cartwheels outside to lunges indoors, that's fine, too. The point is to make exercise fun and a part of everyday life early on.