EFFECTS OF RESISTANCE TRAINING ON REGIONAL AND TOTAL BONE-MINERAL DENSITY IN PREMENOPAUSAL WOMEN - A RANDOMIZED PROSPECTIVE-STUDY

This study was designed to assess the effects of 18 months of resistan ce exercise on regional and total bone mineral density (BMD) and soft tissue lean mass (STL) in premenopausal women aged 28-39 randomly assi gned to an exercise or control group. Twenty-two exercise and 34 contr ol subjects completed the 18-month training study. All subjects were p reviously inactive and untrained women. Initial, 5-, 12- and 18-month assessments were made of total and regional BMD and total and regional STL using dual energy X-ray absorptiometry. All subjects consumed a 5 00 mg/day elemental calcium supplement throughout the study. Initial C a intake without supplement averaged 1,023 mg/day in total sample. Ser um levels of bone osteocalcin and dietary assessments using 12 randoml y assigned days of diet records were also completed, Muscular strength ,vas assessed from both 1 repetition maximum (RM) testing of 10 weight lifting exercises and by peak torque for hip abduction/adduction and k nee extension/flexion. Training increased strength by 58.1% based on 1 RM testing and by 33.8% based on isokinetic testing at 18 months vers us baseline, BMD increased significantly above baseline at the lumbar spine for the exercise group at 5 months (2.8%), 12 months (2.3%), and 18 months (1.9%) as compared with controls, Femur trochanter BMD incr eased significantly (p < 0.05) in the exercise group at 12 months (1.8 %) and 18 months (2.0%) but not at 5 months (0.7%) as compared with co ntrols, No changes in fetal BMD, arm BMD, or leg BMD were found, There was a 20% increase in BGP in the exercise group as compared with cont rols at 5 months and this difference was maintained throughout the stu dy, For STL, significant increases for total, arm, and leg were found at 5, 12, and 18 months for the exercise group versus control ranging from 1-6% over baseline. These results support the use of strength tra ining for increasing STL and muscular strength with smaller but signif icant regional increases in BMD in the premenopausal population.