The Influence of Body Composition and Muscular Strength and Power on Bone Mineral Content and Density in Early Elementary School Children.

Abstract

2053 PURPOSE: To examine the associations between bone mineral content (BMC) and density (BMD) and measures of muscular fitness and body composition in healthy early-elementary school children METHODS: BMD and BMC of the total body (TB) and lumbar spine (LS), and body composition were measured using dual x-ray absorptiometry (DXA) in 101 (50M, 51F) early elementary school children (mean age = 7.2 ± 0.6 yrs). Vertical jump height (VJ) and maximal grip strength (GS) were used to measure muscular power and strength respectively. The influence of body weight (BW), body composition (fat mass (FM), and lean mass (LM)), VJ, and GS on bone was examined using Pearson correlations and multiple linear regression. Age and sex were controlled for in all models and height was controlled for in all models predicting BMC RESULTS: LM was positively correlated with TB and LS BMD and with LS BMC (p < .05), while FM was positively correlated (p < .05) with all parameters of bone. VJ was significantly negatively correlated with FM (p< .05), while GS was significantly positively correlated with LM and FM (p < .05). VJ was positively correlated (p < .05) with TB and LS BMD, while GS was positively correlated (p < .05) with all parameters of bone. Using multiple linear regression, BW and VJ positively predicted TB and LS BMD and BMC. When LM and FM were entered separately, LM, FM, and VJ (p <.05) positively predicted TB and LS BMD and LS BMC. GS and BW were significant predictors (p < .05) of LS BMD and BMD. When LM and FM were entered separately, FM and GS were significant positive predictors of LS BMD, and GS, FM, and LM were significant (p < .05) positive predictors of LS BMC. GS was not predictive of TB BMC or TB BMD. CONCLUSIONS: In young school-aged children, FM, LM and leg power positively predict TB and LS BMD. Muscular strength influences LS BMC and BMD. The positive influence of both FM and LM individually on bone suggests that increased weight and improved muscular fitness exert protective influences on bone health. In light of the ongoing obesity epidemic facing children, interventions designed to improve muscular fitness while controlling BW are an appropriate aim for improving bone health in children.