Effects of isoflavone and counter-resistance training on bone mineral density in postmenopausal women

Abstract

This study aimed to investigate the independent and additive effects of conter-resistance training (RT) and soy isoflavone supplement (ISO) on bone mineral density (BMD) and bone turnover in postmenopausal women. This study used a placebo-controlled, double-blinded (soy), randomized two (ISO vs. placebo) x two (RT vs. no RT) design. Eighty sedentary postmenopausal women, aged 45-70 years, were randomly assigned to one of four groups (71 completed a 9-month intervention): RT+ISO (n=15); no RT+ISO (n=20); RT+placebo (n=18); no RT+placebo (n=18). Participants randomized to ISO received 100mg/day/oral of soy isoflavone; and those to RT attended supervised counter-resistance training sessions at least twice a week. At baseline and 9-month, BMD was estimated by dual-energy X-ray absorptiometry (DXA). Serum levels of C-terminal cross-linked telopeptide of type I collagen (CTX), osteocalcin, and insulin-like growth factor-1 (IGF-1) were measured as boné turnover. ANOVA with time as the repeated measure and test t were used in the statistical analysis. After 9 months of intervention, neither ISO nor RT alone affected BMD at anysite or levels of CTX, osteocalcin, and IGF-1 (p>0.05). ISO and RT had no additive effects on BMD and bone turnover. RT groups showed significantly increased muscle strength (+35.2%) (p=0.02). We found no additive effects of resistance training and soy isoflavone on bone mineral density or bone turnover in postmenopausal women after 9-months.