Skipping has been making a comeback lately, as a simple and fun way to sneak more cardio into your weekly workout. But as it turns out, the simple act of jumping up and down, be it with a skipping rope or without, could have a positive effect on your bones, too.

The impact of exercise on bones is a controversial issue in the world of sports science, as detailed in a recent collection of articles in the December issue of Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine. According to Dr. Daniel W. Barry, a researcher and assistant professor of medicine at the University of Colorado, "There was a time, not so long ago," when most researchers assumed "that any and all activity would be beneficial for bone health." However, researchers have since discovered that only some exercises are effective in strengthening bones, while others -- like swimming, cycling and weight lifting -- are not.

What makes researchers so sure that jumping up and down is the key? Japanese studies involving mice showed a significant increase in bone density when the mice jumped and landed several times a week, over a period of time. "Jumping is great, if your bones are strong enough to begin with," Dr. Barry told the New York Times. "You probably don't need to do a lot, either."

So what are you waiting for? Grab that old skipping rope, and hop to it! Your bones will thank you.