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 fra ctures could be modified by high-intensity strength training exercises in postmenopausal women. Design.-Randomized controlled trial of 1-yea r 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 subj ects were sedentary and estrogen-deplete. Interventions.-High-intensit y strength training exercises 2 days per week using five different exe rcises (n=20) vs untreated controls (n=19). Main Outcome Measures.-Dua l-energy x-ray absorptiometry for bone status, one repetition maximum for muscle strength, 24-hour urinary creatinine for muscle mass, and b ackward tandem walk for dynamic balance. Results.-Femoral neck bone mi neral density and lumbar spine bone mineral density increased by 0.005 +/-0.039 g/cm(2) (0.9%+/-4.5%) (mean+/-SD) and 0.009+/-0.033 g/cm(2) ( 1.0%+/-3.6%), respectively, in the strength-trained women and decrease d by -0.022+/-0.035 g/cm(2) (-2.5%+/-3.8%) and -0.019+/-0.035 g/cm(2) (-1.8%+/-3.5%), respectively, in the controls (P=.02 and .04). Total b ody 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 (-3377 g; -1.2%+/-3.4%, P=.12). Muscle mass, muscle strength, and dynamic balance increased in the strength-trained women and decreased in the c ontrols (P=.03 to <.001). Conclusions.-High-intensity strength trainin g exercises are an effective and feasible means to preserve bone densi ty while improving muscle mass, strength, and balance in postmenopausa l women.