Rocky did it. Superstar boxer Manny Pacquiao does it. And third graders with pigtails have always done it. It's jumping rope. Should you do it?

Some gyms are now focusing classes and even structuring their businesses aroung jump-roping, claiming that the benefits of jumping rope outweigh some traditional cardiovascular training methods.

From the New York Times:

Edward Jackowski, who also wrote the book "Jump Into Fitness," describes jumping rope as an intensive cardiovascular workout that has one-fifth the impact on the back and the knees as running and burns more calories in less time. "Jumping rope for 10 minutes at 150 turns per minute is equal to 30 minutes of running between six and seven miles per hour," he said.

Hold on: 150 turns per minute? Yeah, that's a lot more intense than the double-dutch you're likely to see during recess at the local elementary school. If you do the math, 150 turns per minute is two-and-a-half jumps per second.

Can Pacquiao even do that? And should he?

"My assumption would be that jump-roping - even more than running - could predispose folks to a lot of repetitive stress injuries because of the low amplitude (range of motion) of the movement," says Boston-area strength coach Eric Cressey. "Factor in that most folks starting this seem to be overweight and detrained, and you're likely asking for something bad to happen."

Even if you worked your way up to 150 RPM levels, your body's adaptation ability would be playing directly against you. The longer you do a specific form of exercise, the more efficient you become at it. It's the body's natural statement of practice makes perfect.

"The longer you do a single modality of exercise," says Cressey, "the more efficient you become at it -- meaning that you burn fewer calories for the same effort. Just jumping rope all the time isn't going to do much after a few months."

So if you've been pounding away at the elliptical for six months and haven't seen results, jumping rope may be a great change of pace, assuming you start out gradually. However, if you're truly looking for an effective change-up to your normal cardio workout, Cressey recommends getting off the cardio machines entirely and focusing on strength training.

Exercises like push-ups, squats and lunges can help you build muscle, lose weight and, most importantly, they are more applicable to every day life. You're more likely to have to squat down to pick up a box than jump in place 60 times to change a light bulb.

"I think (jump roping) would be okay in small volumes," Cressey says. "It would be far from my first choice -- even in folks with minimal equipment. There are loads of body-weight-only exercises folks can use that would provide greater fat loss, strength development, and mobility improvements with less risk of injury."

So be like Rocky: jump rope a little, but make sure to hit the hanging meat -- or the weights -- even more.