Effects of high-intensity resistance exercise on bone mineral density and muscle strength of 40-50-year-old women.

OBJECTIVE

The purpose of the study was to determine the effect of six months of heavy resistance training (weightlifting) on the bone density of premenopausal women.

EXPERIMENTAL DESIGN

A 6-month prospective design with random assignment to groups.

SETTING

Measurements of bone mineral density (BMD) were obtained from the Radiology Clinic at North Carolina Memorial Hospital. Exercise sessions were completed in the Physical Education Department facilities at the University of North Carolina, Chapel Hill, NC.

PARTICIPANTS

Thirty-five premenopausal women, 40-50 years of age, were randomly assigned to either a resistance training (RT) and sedentary control (CON) group. The study finished with 12 women exercising and 14 in the control group.

INTERVENTION

The resistance training consisted of three days per week of high-intensity weightlifting specifically designed to place strain on the spine and hips.

MEASURES

Bone density of the lumbar vertebrae, femoral neck, and distal radius, were determined prior to and at the end of the exercise program using dual energy X-ray absorptiometry (DEXA).

RESULTS

Resistance-training produced strength gains: overhead press = 125%, leg press = 86%, and calf raises = 91% (p < 0.001). RT tended to increased lumbar BMD 1.03%, while the CON decreased 0.36% (p = 0.072). Both groups lost radial BMD (CON = -0.45%; RT = -1.04%). Both groups gained femoral neck BMD (CON = 1.26%; RT = 1.22%).

CONCLUSIONS

These results suggest that even a short-term weight training program can either maintain or improve the BMD of the femoral neck and lumbar vertebrae in premenopausal women.