Fitness & Exercise

Kicking Your Way to Fitness

Every few years, a new class takes the fitness world by storm. In the late '80s, Jane Fonda and her ponytail-bobbing, leg-warmer-wearing aerobics classes were all the rage. In the early '90s, the step bench was introduced and heart-pounding step aerobics quickly became the yardstick by which all other sweat-and-spandex endeavors were measured. Now there's cardio-kickboxing, offered by nearly 80% of health clubs nationwide.

Sometimes called boxing aerobics or just plain kickboxing, cardio-kickboxing is a hybrid of boxing, martial arts, and aerobic dance that offers a high-intensity, aggression-releasing workout without the mind-numbing boredom that can come with some other gym-bound activities. But even this fad comes with a drawback: While its popularity continues to rise, so do reports of injuries. With cardio-kickboxing, it's especially wise to get some basic training info before you start throwing punches.

Why the Kickboxing Craze?

According to a recent study by the American Council on Exercise (ACE), cardio-kickboxing participants can expect to burn an average of 350 to 450 calories per hour and maintain a heart rate at 75% to 85% of maximum, well within the recommended 65% to 85% range for aerobic exercise. An hour-long session is roughly equivalent to an hour of brisk walking or light jogging. But cardio-kickboxing has a distinct advantage -- it's a truly versatile, cross-training workout. Neither of the pedestrian activities improves strength, flexibility, coordination, and reflexes the way cardio-kickboxing does.

"You burn tons of calories and get into terrific aerobic shape without having to run miles and miles," says Dan Hamner, MD, a sports medicine and rehabilitation specialist who works with competitive fighters and martial artists in New York City.

Unlike the incessant step-kick-repeat combinations you're likely to master in step aerobics class, the moves in cardio-kickboxing actually can have some real-life application. As you punch, jab, and protect your face from an (imagined) attacker, you're learning to protect yourself, only without the bruises. By practicing some simple self-defense moves in a fun atmosphere, many people -- women especially -- gain a greater sense of empowerment and self-confidence.

But you needn't have the desire to smack someone to participate. The only punches you'll throw in most cardio-kickboxing classes are into the air while you jog in place or shuffle from side to side; some classes provide punching bags, but this is the exception, not the rule.

Don't Let an Injury Put You on the Ropes

If step aerobics can be hell on your knees, careless cardio-kickboxing fans may wind up with other creaky parts. In fact, with kickboxing, there's a fairly significant risk of injury. Participants throw punches with such gusto that their elbows, shoulders, knees, and lower backs often pay the price. Extensor tendonitis (commonly called "tennis elbow"), overuse injuries of the knee, and strained groin and back muscles top the list of injuries, says Hamner, who's also a spokesperson for the American College of Sports Medicine.