Relationship of sarcopenia with bone geometry and mass among postmenopausal women.

OBJECTIVE: The aim of this study was to verify whether sarcopenia and its components are associated with hip areal bone mineral density (aBMD) and geometry in postmenopausal women (PW). METHODS: In this cross-sectional study, appendicular bone-free lean mass (aLM) and hip bone mass and geometry were measured using dual-energy x-ray emission absorptiometry (DXA). Muscle power and strength were measured by five times Sit-to-Stand Test (5-STS) and dynamometry, respectively, in 175 PW. Sarcopenia was identified as low aLM plus low muscle strength or low muscle power. Multiple linear regression (covaried by age, smoking, hormonal therapy, and diseases) was used to determine the relationship between sarcopenia and bone geometry and mass. The results are presented as mean differences between groups. RESULTS: Dynamometry, five times Sit-to-Stand Test, and aLM indicated positive associations (P < 0.05) with most indicators of bone mass and geometry. Sarcopenia, applying low muscle strength or low muscle power, was negatively associated with femoral neck width (-0.2 mm, P = 0.001), cortical thickness of femoral calcar (-0.6 mm, P = 0.043), subtrochanteric cortical thickness (-1.2 mm, P = 0.002), femoral neck cross-sectional area (-19.5 mm2, P < 0.001), cross-section moment of inertia (-2,244 mm4, P < 0.001), section modulus (-115 mm3, P < 0.001), femoral neck aBMD (-0.1 g/cm2, P = 0.002), upper femoral neck aBMD (-0.1 g/cm2, P = 0.003), lower femoral neck aBMD (-0.1 g/cm2, P = 0.016), and trochanteric aBMD (-0.1 g/cm2, P = 0.035). CONCLUSIONS: Thus, muscle mass, strength and power, alone or in combination (ie, sarcopenia), are associated with low aBMD, impaired bone geometry, and, therefore, bone strength in PW. These measures may help identify PW at risk of hip fractures.

Resistance training and hormone replacement increase MMP-2 activity, quality and quantity of bone in ovariectomized rats

AIMS: The aim of the present study was to investigate the influence of resistance training (RT) and hormone replacement (HR) on MMP-2 activity, biomechanical and physical properties bone of ovariectomized (OVX) rats. METHODS: Sprague-Dawley female rats were grouped into six experimental groups (n = 11 per group): sham-operated sedentary (SHAM Sed), ovariectomized sedentary (OVX Sed), sham-operated resistance training (SHAM RT), ovariectomized resistance training (OVX RT), ovariectomized sedentary hormone replacement (OVX Sed-HR), and ovariectomized resistance training hormone replacement (OVX RT-HR). HR groups received implanted silastic capsules with a 5% solution of 17ß-estradiol (50 mg 17ß-estradiol/ml of sunflower oil). In a 12-week RT period (27 sessions; 4-9 climbs) the animals climbed a 1.1 m vertical ladder with weights attached to their tails. Biomechanical and physical bone analyses were performed using a universal testing machine, and MMP-2 activity analysis was done by zymography. RESULTS: Bone density and bone mineral content was higher in the RT and HR groups. The MMP-2 activity was higher in the RT and HR groups. The biomechanical analysis (stiffness, fracture load and maximum load) demonstrated better bone tissue quality in the RT associated with HR. CONCLUSION: The RT alone as well as when it is associated with HR was efficient in increasing MMP-2 activity, biomechanical and biophysical properties bone of ovariectomized rats.(AU)