Morbidity and mortality are associated with osteoporosis and sarcopenia. There are few data describing the associations between functional measures of muscle and bone. Therefore, the aim of this study was to examine the associations of muscle strength and tibial bone outcomes in ageing men.
Men (n=301) aged 4085 years were recruited in UK (201-White, 43-Black, 57-South-Asian). pQCT was performed at the 38 and 66% tibia with the outcome measures: cortical bone mineral content (Ct.BMC), cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI). Muscle strength was assessed by jumping mechanography: a single 2-leg counter-jump to calculate muscle force (kN) and power (kW). Linear regression was used to explore the relationship between force and bone outcomes, adjusting for ethnicity, age, weight and height. Similar analyses were used to identify the effects of power and age, and included pairwise comparisons due to finding ethnicity-age interactions. Results are expressed as β-coefficients (95% CI) of percentage unit change in force/age.
Muscle force was a significant predictor of bone. At the 38% site, for every 1-unit increase in force, there was an increase of 8.5% (3.6, 13.4) in Ct.BMC; 9.3% (5.4, 13.2) in CSA and 18.6% (11.1, 26.2) in CSMI (all P<0.001). Similar effects were seen at the 66% site. There were no effects of ethnicity in force predicting tibial bone outcomes. Muscle power significantly declined with age in all groups: Whites (−1.9%; −2.1, −1.7), Blacks (−1.3%; −1.8, −0.8), South-Asians (−1.8%; −2.3, −1.3). There was a trend for an interaction with ethnicity in the power and age relationship, with a significant difference between White and Black men (P=0.03).
Muscle force positively predicted bone outcomes in ageing men. An absence of an ethnic effect suggests biomechanical adaptations are the main driver of this association. In contrast, the relationship between power and age was different between ethnicities suggesting a greater environmental influence which may contribute to falls.
14 - 17 May 2016
European Calcified Tissue Society