Build Bone Density with Aerobic Exercise

Build Bone Density with Aerobic Exercise
Dr. Michael Liang uses a Mechanical Response Tissue Analyzer to measure bone strength of subject Sandia Cano's tibia as part of a $1.4 million research study at Cal Poly Pomona.

There is much to be said for sitting quietly and watching the world go by. However, Cal Poly Pomona researchers want to eject us from our comfy armchairs and get us moving. Not only are we to move in an aerobic way, but we are also to perform high repetition, weight-bearing step aerobics. Why? To prevent osteoporosis, of course.

Osteoporosis is characterized by a decrease in bone mass and density, causing bones to become fragile. However, it can be treated and, interestingly enough, bone mineral density can be increased.

In a one-year study of 51 healthy but sedentary young women, a team of researchers from Cal Poly Pomona, UC Irvine's College of Medicine and the NASA Ames Research Center randomly assigned women to one of three groups: aerobics, strength training and control. The aerobics group did step aerobics three times a week for 12 months and increased the bone mineral density of their heels and first lumbar spines. The strength training group, which focused its workout efforts on lower body muscular strength training, did not achieve bone density growth, nor did the control group, which simply performed mild outdoor and at-home activities. In fact, women in the strength training and control groups often showed small decreases in lower body bone mineral density, despite the fact that all women received 100 mg of daily calcium supplements.

“Research subjects experienced an increase of 4.4 percent in bone mineral density in the heel and a small increase of 1.4 percent in the lumbar spine by taking part in high-repetition, impact-loaded aerobic exercise,” says Cal Poly Pomona kinesiology & health promotions professor Michael T. C. Liang. “But it's important to recognize the value of strength training on the bones and to incorporate exercises of the upper body to prevent bone mineral loss in that area.”

The study is unique because it focuses on young women whose skeletal systems are at their peak and who believe they have 30 or so years before becoming concerned with terms such as “osteoporosis” and “bone density loss.” Most previous studies on the relationships between exercise and bone health have been performed on post-menopausal women whose bone density is already decreasing. The research was funded by a $1.4 million grant from the National Institutes of Health. Dr. Liang hopes to advance the study to discover whether lifestyle, diet, leisure-time activities or other factors can affect bone health for young women of different ethnic and/or racial groups.