Bone mineral density in well-trained females with different hormonal profiles

Objective: The association between sex hormones and bone mineral density (BMD) has been studied in sedentary women, whereas only few studies have evaluated trained females. Therefore, the aim of this study was to assess the influence of sex hormones on BMD in well-trained females with different hormonal profiles: eumenorrheic females, oral contraceptive (OC) users and postmenopausal women. The secondary purpose was to determine if maximal oxygen consumption (V̇ O2max) or maximal back squat strength (1RM) could be good predictors of BMD in this population. Methods: Sixty-eight eumenorrheic, forty-one monophasic-OC users and sixteen postmenopausal well-trained females participated in this study. A Dual-energy X-ray Absorptiometry scan (DXA), a basal blood sample and a maximal back squat and/or a maximal treadmill test were performed. In order to measure all volunteers under similar hormonal conditions (low sex hormone levels), all tests were carried out during the early follicular phase for the eumenorrheic females and in the withdrawal phase for the OC group. Results: One way ANCOVA reported lower values of BMD in postmenopausal (1.13±0.07g/cm2) than in eumenorrheic (1.19±0.08 g/cm2) (p=0.003) and OC users (1.17±0.07 g/cm2) (p=0.030). Pearson´s correlation showed a positive relationship between BMD and 1RM (p<0.001), but not with V̇ O2max. Conclusions: Lower BMD has been reported in postmenopausal women compared to both, eumenorrheic females and OC users. BMD loss after menopause seems to be not fully compensated by exercise, but this could effectively mitigate it. Moreover, 1RM back squat reported a slight association to BMD. Hence, strength training may be the best choice to prevent BMD loss.