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

Purpose: The purpose of this study was to compare the effects of a high-loa d (80%, 1-repetition maximum (RM). 8 reps) and a high-repetition (40%, 1-RM , 16 reps) resistance training protocol on muscular strength and bone miner al density (BMD) in early postmenopausal, estrogen-deficient women. The 6-m onth programs were matched initially for training volume (3 sets, 3 d.wk(-1 )) for 12 exercises selected to specifically load the spine and hip. Method s: 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 (H R, N = 7), or control (C, N = 8) groups. Dietary calcium intakes were suppl emented to similar to 1500 mg.d(-1). Total body, spine, and hip BMD (DXA, L unar Model DPX-IQ), upper and lower body muscular strength, and biochemical mai kt rs of bone turnover were measured at baseline and after 6 months of training. Results: There were no group differences in the baseline measure s. Both training groups showed similar increases in biceps (20%) and rectus femoris (28-33%) cross-sectional areas, in lower body strength (similar to 30%) and in hip strength (37-40%). HL showed greater improvements in upper body strength (HL 25%, HR 16%.). Neither training group experienced signif icant increases in spine or hip BMD, although the HI, 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 8 change in os teocalcin 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. Conclusion: The high -load and high-repetition resistance training protocols were both effective in improving muscular strength and size in postmenopausal women, indicatin g low-intensity resistance training can be beneficial for the muscular fitn ess in women for whom high-intensity exercise is contraindicated.