If you haven't jumped rope since grade school, you're missing out. This kid-friendly piece of fitness equipment is portable, simple to use, and takes the work out of working out. No wonder it's earning rave reviews among trainers these days. 

"Jumping rope is my all-time-favorite best-bang-for-your-buck workout," says Leanne Shear, a personal trainer and cofounder of Uplift Studios in New York City. "It offers a huge burst of cardio; improves endurance, stamina, and speed; and the great part is, it's a very intense workout that requires very little time." Shear also touts it as a supplemental exercise for those times when you're not in the mood to go for a run or hit up yet another cycling class. "It's also good to do a minute of jumping rope between strength-training sets," she says. "Just five to 10 minutes a day is enough to start seeing benefits." 

MORE: The 7-Move 7-Minute Workout That Blasts Fat Fast  

Ready to give it a try? Before you do, note that jumping rope can be harder on the body than you remember from when you were a kid. "Make sure to stretch, especially your quads, hamstrings and calves," says Shear. Once you're appropriately limbered up, grab a rope and give these three variations a try. 

Classic jumping rope: With your fit spread hip-width apart, jump rope with both feet, moving the rope around your body with your wrists and keeping a fast but steady pace. Your hips should remain level as you jump.

One-foot jumping: Do the same move as above, but hop on one leg, then the other, which helps improve balance and strengthen leg muscles. "I alternate a minute on one leg, then a minute on the other," says Shear. 

Lateral jumps: Jump rope fast with your feet together, but add in a side-to-side motion. "This works the lateral muscles of the legs and also gets in a little shot at the obliques," says Shear.

MORE: The Ultimate Boot-Camp Workout