Overdoing it with aerobics

Whether you go to an aerobic dance class or work out with Jane Fonda on videotape, if you’re one of the 24 million Americans who participates in aerobic dance programs, you’re on the right track to physical fitness. Aerobic dance programs and other aerobic exercise like walking, running, swimming, and bicycling improve heart and lung function and offer all those other benefits you know by heart: better quality of life, decreased risk of heart disease, lower blood pressure, less stress, and more energy.

But (and it’s a big one) you can get too much of a good thing. Injuries associated with excessive amounts of aerobic exercise include stress fractures, shin splints, muscle pain, knee and ankle damage, back and foot problems, and (during hot, humid weather) heat exhaustion. Some people even develop “exercise addiction,” continuing intense programs in spite of chronic fatigue and problems with work or family relationships caused by an unreasonable drive to exercise.

Experts emphasize that benefits of moderate exercise programs far outweigh risks, but they also warn that increasing the amount and intensity beyond moderate levels increases the chance of exercise-related problems. Generally, a session that lasts longer than 45 minutes with the intensity of hard running carries a danger of injury. On the other hand, a session lasting less than 20 minutes has very little positive effect on the cardiovascular system.

High- vs. Low-Impact

In the early 1980s, health problems first noticed in aerobic dance program participants were attributed to the high-impact nature of the exercise: the jolting and pounding that results from having both feet off the floor at the same time. Concrete floors also contributed to stress on joints, as did improper shoes that didn’t give the stability, shock absorption, and flexibility needed. Researchers have since spent time looking for ways to improve aerobic dance facilities, shoes, and choreography to make programs safer without losing cardiovascular benefits.

The challenge was met in other ways, too. Low-impact programs were introduced, in which one foot is always touching the ground. Low-impact aerobics involve less jarring and cause fewer injuries. Still, the exercise are not injury-free. Ankle and knee injuries can nevertheless occur and without proper guidance, you might not get the heart and lung workout you seek.

Move Around

Still, benefits of a good low-impact program can equal those of a high-impact workout if participants use multi-directional, full-body movements. What does this mean? In every session: Move around the room often and change direction frequently; use the large muscle groups in the legs, hips, and back; and use smooth, controlled movements.

Your instructor should always explain each exercise, especially proper position and placement. If you’re not doing a movement correctly, you won’t get the benefits, and you could hurt yourself.

As for the intensity of your workout, one easy way to be sure you’re not exercising too hard is the “talk test.” You should be able to carry on a conversation during your workout. If you’re breathing too hard to do that, your intensity is too high.

Stretching, the Myth

Finally, the myth that injury can be prevented by stretching before exercise has been called into doubt by a study at the University of South Carolina. Researchers found no difference in injury rates among runners who stretched before their workout and those who didn’t. In fact, they found some evidence that improper stretching may even cause pulled or torn muscles. (Competitive athletes in sports such as tennis or volleyball with a lot of stop-and-go and those that require a full range of motion of joints such as gymnastics may still benefit from pre-workout stretching.)

Other studies show that a few minutes of warm-up jogging, walking, or bicycling before exercise sessions prevent injury by helping muscles absorb more force and making them less likely to tear. A gradual cool-down, such as walking after jogging or slow swimming after a tough practice may do more good than post-exercise stretching.

What this all means is you don’t need a “no-pain no-gain” workout to benefit from aerobic exercise. If you work at your own pace and use habits that work for you, you’ll improve your health and fitness–without overdoing it.