1. Archive

Step-aerobic exercise precautions suggested

Published Oct. 9, 2005

Question: Could you comment on the safety of step aerobics? Besides being somewhat boring, I wonder if it will keep orthopedic surgeons busy for years to come?

Answer: Step aerobics (bench aerobics or bench stepping) arrived on the fitness scene in the late 1980s and is now a basic program at most health and fitness centers.

Like any activity, if you do it wrong or too often, it can cause injuries that could require the services of an orthopedic surgeon, but the activity is generally safe and has a lot going for it.

It's mostly a low impact activity that doesn't place high impact stress on the joints.

Step aerobics is excellent for improving cardiovascular fitness _ right up there with running and jogging. The activity can also accommodate many fitness levels at the same time since the platforms are adjustable, and the mix of platforms, dance steps, arm movements and music is fun for many folks.

Does it cause undue injuries? There are no national injury reports that provide an answer to this question.

There is, however, one specific concern, that is, excessive muscle soreness. Translation: As you step down from the platform, the muscles of the leg doing the lowering must apply force to lower you gently, while at the same time they are lengthening to allow your knee to bend.

When muscles lengthen and also apply force, it's called Negative Muscle Action. When stepping up, you place your lead foot on the platform and then straighten the leg by contracting or shortening the thigh muscles. When muscles shorten and apply force, it's called Positive Muscle Action.

Negative Muscle Action places more stress on muscle tissue than the Positive Muscle Action. As a result, microscopic muscle damage increases (some muscle damage is associated with all strenuous exercise).

This leads to excessive soreness, swelling and loss of strength (particularly around the knee joint). Moreover, the damage tends to progress slowly, and it may not interfere with workouts until serious harm has been done.

To avoid this problem and other potential overuse injuries associated with step aerobics, the American College of Sports Medicine suggests the following precautions:

Select a platform height appropriate to your fitness level (4 inches for beginners and no more than 12 inches for trained steppers).

Master your footwork before adding the arm movements.

Contact the surface of the platform with the entire sole of your foot.

Step close to the platform.

Avoid locking your knee during the step up or step down.

Step softly onto the platform (and the floor) to control.

Alternate your lead step at least every minute or so.

Do no more than five repeaters per leg before switching to the other side.

Step up and down facing the platform (stepping down with your back to the platform can increase impact forces by 25 percent).

Keep your stepping cadence below 122 steps a minute.

Calcium supplements

Question: I read an article that said, "Women on calcium supplements experience a significant decline in high density lipoprotein levels." Is this so?

Answer: No. There is no apparent negative connection between HDL and calcium.

High density lipoprotein (HDL) is, of course, the "good" cholesterol that helps to clear "bad" LDL cholesterol from the body thereby decreasing our risk of heart disease. Calcium protects against the development of osteoporosis in women and age related bone loss in men. An intake of 1,000 to 1,500 milligrams per day, taken through diet or supplements, is recommended (the higher amount for all women past menopause who are not on estrogen). Calcium is also associated with decreases in hypertension and colon cancer.

Write with questions to Dr. Patrick J. Bird, dean of the College of Health and Human Performance, University of Florida, Gainesville, FL 32611.