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INFLUENCE OF MUSCLE STRENGTH ON BMD FOLLOWING WEIGHT LOSS AND WEIGHT REGAIN IN PREMENOPAUSAL WOMEN

Abstract

BACKGROUND: Many studies have demonstrated a decrease in absolute bone mineral density (BMD) with weight (wt) loss; however, few have examined adjusted changes in BMD with wt loss and wt regain with muscular strength. The purpose of this research was to see associations between BMD after wt loss with muscular strength. METHODS: 43 women (34.6+/-5.8 yrs) underwent diet induced wt loss. BMD was assessed by dual energy x-ray absorptiometry (DXA). BMD was adjusted for wt, age, sex, and race to obtain BMD z-scores. Maximal isometric bicep and quadriceps strength was assessed in the overweight (OW) state. Subjects were divided into tertiles by muscular strength. Group comparisons were made using repeated measures ANOVA at OW, post-wt loss (PW), and 1-year follow-up (FU). RESULTS: Subjects lost 13.0+/-3.2 kg. At FU subjects regained 4.0+/-5.2 kg. BMD did not decrease at PW and FU. Z-BMD increased at PW (p=0.00, OW 0.20+/-0.72 vs PW 0.29=/-0.82); however, z-BMD at FU decreased from PW (p=0.001). There were significant relationships between bicep strength and changes in BMD from OW to PW. There were significant relationships between quadriceps strength and changes in BMD from OW to FU and PW to FU. Subjects in the lowest strength tertile lost more BMD compared to the highest tertile at both PW (low 0.007+/-0.02 vs. high 0.0005+/-0.01 kg/m2) and FU (low 0.008+/-0.02 vs high -0.01+/-0.03 kg/m2). CONCLUSIONS: Diet induced wt loss was associated with changes in adjusted BMD and was higher after weight loss. These results suggest that stronger individuals lose less BMD following wt loss. The protective effects of strength on BMD may persist for up to 12-months post wt loss in premenopausal women. Supported by NIH RO1 DK-49779 and RO1 DK-51684, NCRR RR 11811, UAB GCRC MO1-RR-32.

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