Effects of high-intensity strength training on multiple risk factors for osteoporotic fractures. A randomized controlled trial

Objective. —To determine how multiple risk factors for osteoporotic fractures could be modified by high-intensity strength training exercises in postmenopausal women. Design. —Randomized controlled trial of 1-year duration. Setting. —Exercise laboratory at Tufts University, Boston, Mass. Population. —Forty postmenopausal white women, 50 to 70 years of age, participated in the study; 39 women completed the study. The subjects were sedentary and estrogen-deplete. Interventions. —High-intensity strength training exercises 2 days per week using five different exercises (n=20) vs untreated controls (n=19). Main Outcome Measures. —Dual energy x-ray absorptiometry for bone status, one repetition maximum for muscle strength, 24-hour urinary creatinine for muscle mass, and backward tandem walk for dynamic balance. Results. —Femoral neck bone mineral density and lumbar spine bone mineral density increased by 0.005±0.039 g/cm2(0.9%±4.5%) (mean±SD) and 0.009±0.033 g/cm2(10%±3.6%), respectively, in the strength-trained women and decreased by -0.022±0.035 g/cm2(-2.5%±3.8%) and -0.019±0.035 g/cm2(-1.8%±3.5%), respectively, in the controls (P=.02 and.04). Total body bone mineral content was preserved in the strength-trained women (+2.0±68 g; 0.0%±3.0%) and tended to decrease in the controls (-33+77 g; -1.2%±3.4%,P=.12). Muscle mass, muscle strength, and dynamic balance increased in the strength-trained women and decreased in the controls (P=.03 to Conclusions. —High-intensity strength training exercises are an effective and feasible means to preserve bone density while improving muscle mass, strength, and balance in postmenopausal women. (JAMA. 1994;272:1909-1914)