Abstract
Osteoporosis is considered a pediatric disease with geriatric consequences. However, measuring bone strength in children is complex and creates a practical problem for health professionals, teachers and parents. A non-invasive measure of muscle fitness that correlates to bone strength may provide a means to monitor bone strength throughout the lifespan. Therefore, the purpose of this study was to investigate the relationship between common muscle function tests (relative grip strength (RGS), peak vertical jump power (PP)) and bone strength in the radial diaphysis and epiphysis of a healthy population. Healthy participants (n=147 (81 female)) performed a bilateral grip strength test using a hand dynamometer, and a maximal vertical jump test. Peak vertical jump power was calculated from maximal jump height using the Sayer’s equation. Moment of inertia (MoI), cortical area (CoA), cortical bone mineral density (cBMD), and polar strength-strain index (SSIp) were measured using peripheral Quantitative Computed Tomography (pQCT) to determine bone strength parameters at the 66% radial site (predominantly cortical bone). At the 4% site (trabecular bone site), bone mineral content (vBMC.tb), bone mineral density (vBMD.tb), total area (ToA.tb) and bone strength index (BSIc) were measured. Hierarchical multiple regression analyses determined the relationship of each muscle function test for each bone envelope (cortical and trabecular). For the cortical bone measurements: RGS, and PP were both significantly correlated with CoA, MoI, and SSIp. Peak vertical jump power predicted bone strength parameters to a greater extent compared to RGS. For the trabecular bone envelope, RGS was not a predictor of bone strength however peak power was a significant predictor of bone strength parameters. Peak vertical jump power was a significant predictor of bone strength at both trabecular and cortical radial sites. Interestingly PP, a lower limb measurement explained the most variance in the bone strength of the upper limb.