Influence Of Measures Of Body Composition On Vascular Function In Children.

Abstract

Brachial artery flow mediated dilation (FMD) has become a commonly applied technique for the assessment of vascular health in humans. Although shear stress and artery size are acknowledged determinants of the FMD response, recent studies suggest that FMD is also governed by other factors. PURPOSE: To investigate the relationships between vascular function and body composition variables in children. METHODS: FMD (FMD%) was recorded and then normalised for the stimulus shear rate (FMD/SRAUC) in 129 healthy children (75 female; 10.3±0.3 yrs; 54 male; 10.4±0.3yrs). Body composition variables (mass, lean mass and fat mass in the whole body, arm and forearm) were assessed by DEXA. Bivariate correlations explored the association between FMD%, FMD/SRAUC and body composition variables. A stepwise multiple linear regression investigated the relative contribution of baseline diameter, SRAUC and body composition variables to FMD%. RESULTS: FMD% significantly (p<0.05) correlated with arm fat mass (r=-0.18) and forearm fat mass (r=-0.201). FMD/SRAUC significantly correlated with whole body mass (r=-0.26), whole body fat mass (r=-0.24), arm mass (r=-0.25), arm fat mass (r=-0.28), forearm mass (r=0.194) and forearm fat mass (r=0.211). Baseline artery diameter accounted for 13.5 % of the variation in FMD%, while shear rate stimulus and body composition variables did not significantly contribute to FMD% prediction. Significant correlations were observed between baseline artery diameter and whole body mass (r=0.21), whole body lean mass (r=0.28), arm mass (r=0.23), arm lean mass (r=0.32), forearm mass (r=0.24) and forearm lean mass (r=0.31). CONCLUSIONS: Significant correlations were observed between FMD%, FMD/SRAUC and measures of total and fat mass suggestive that fat mass has a negative association with vascular health. Although whole body and segmental body composition variables exert a relatively weak influence with regard to the determination of vascular function in children, further research might focus on the utility of ratio and allometric scaling procedures to explain the magnitude of the FMD response.