Fat-free mass may play a dominant role in the association between systolic blood pressure and body composition in children and adolescents

Systolic blood pressure (SBP) is significantly associated with body composition in children and adolescents. However, which one of the components of body composition is the dominant contributor to SBP in children and adolescents remains unclear. We, therefore, aimed to determine the dominant contributor to SBP among components of body composition in a large cohort of American children and adolescents derived from the National Health and Nutrition Examination Survey with cross-sectional analysis. In total, 13 618 children and adolescents (median age 13 years; 6107 girls) with available data on whole-body dual-emission X-ray absorptiometry measurements were included. Multiple linear regression showed that SBP was associated with higher total fat-free mass in boys (beta = 0 center dot 49, P < 0 center dot 001) and girls (beta = 0 center dot 47, P < 0 center dot 001) and with higher total fat mass only in boys (beta = 0 center dot 12, P < 0 center dot 001) after adjustment for covariates. When taking fat distribution into consideration, SBP was associated with higher trunk fat mass (boys: beta = 0 center dot 28, P < 0 center dot 001; girls: beta = 0 center dot 15, P < 0 center dot 001) but negatively associated with leg fat mass (Boys: beta = -0 center dot 14, P < 0 center dot 001; Girls: beta = -0 center dot 11, P < 0 center dot 001), in both boys and girls. Dominance analysis showed that total fat-free mass was the dominant contributor to SBP (boys: 49 %; girls: 55 center dot 3 %), followed by trunk fat mass (boys: 32 center dot 1 %; girls: 26 center dot 9 %); leg fat mass contributed the least to SBP in boys (18 center dot 9 %) and girls (17 center dot 8 %). Our findings indicated that total fat-free mass was not only associated with SBP but also the most dominant contributor to SBP variation in American children and adolescents.