Musculoskeletal responses to high- and low-intensity resistance training in early postmenopausal women

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Abstract
BEMBEN, D. A., N. L. FETTERS, M. G. BEMBEN, N. NABAVI, and E. T. KOH. Musculoskeletal responses to high- and low-intensity resistance training in early postmenopausal women. Med. Sci. Sports Exerc., Vol. 32, No. 11, pp. 1949–1957, 2000. The purpose of this study was to compare the effects of a high-load (80%, 1-repetition maximum (RM), 8 reps) and a high-repetition (40%, 1-RM, 16 reps) resistance training protocol on muscular strength and bone mineral density (BMD) in early postmenopausal, estrogen-deficient women. The 6-month programs were matched initially for training volume (3 sets, 3 d·wk−1) for 12 exercises selected to specifically load the spine and hip. Subjects included 25 women (41–60 yr) who were matched by spine BMD then randomly assigned to either the high-load (HL, N = 10), high-repetition (HR, N = 7), or control (C, N = 8) groups. Dietary calcium intakes were supplemented to ∼1500 mg·d−1. Total body, spine, and hip BMD (DXA, Lunar Model DPX-IQ), upper and lower body muscular strength, and biochemical markers of bone turnover were measured at baseline and after 6 months of training. There were no group differences in the baseline measures. Both training groups showed similar increases in biceps (20%) and rectus femoris (28–33%) cross-sectional areas, in lower body strength (∼30%) and in hip strength (37–40%). HL showed greater improvements in upper body strength (HL 25%, HR 16%). Neither training group experienced significant increases in spine or hip BMD, although the HL total body BMD tended to decrease (−1.1% ± 0.4, P = 0.054) after training. Osteocalcin tended to increase (P = 0.08) in all groups after training, and the % change in osteocalcin was positively related to % changes in the total hip (r = 0.41, P = 0.048) and the trochanter (r = 0.42, P = 0.04) BMD. The high-load and high-repetition resistance training protocols were both effective in improving muscular strength and size in postmenopausal women, indicating low-intensity resistance training can be beneficial for the muscular fitness in women for whom high-intensity exercise is contraindicated.