Fat-free mass dominates the relationship between body composition and systolic blood pressure in children and adolescents

Objective: Systolic blood pressure (SBP) significantly associates with body composition. However, which one of the components of body composition is the dominant contributor to SBP in children and adolescents remains unclear. We 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. Design and method: 13618 children and adolescents (median age 13 years; 6107 girls) with available data on whole-body dual-emission X-ray absorptiometry measurements were included. Results: Multiple linear regression showed that SBP significantly associated with fat-free mass in boys (↓ = 0.49, P<0.001) and girls (↓ = 0.47, P<0.001) and with total fat mass only in boys (↓ = 0.12, P<0.001), after adjustment for covariates. When taking fat distribution into consideration, SBP positively associated with trunk fat mass (Boys: ↓ = 0.28, P<0.001; Girls: ↓ = 0.15, P<0.001), but negatively associated with leg fat mass (Boys: ↓ = -0.14, P<0.001; Girls: ↓ = -0.11, P<0.001), in both boys and girls. Dominance analysis showed that fat-free mass was the dominant contributor to SBP (boys: 49%; girls: 55.3%), followed by trunk fat mass (boys: 32.1%; girls: 26.9%); leg fat mass contributed the least to SBP in boys (18.9%) and girls (17.8%). Conclusions: Fat-free mass was not only significantly associated with SBP, but also the most dominant contributor to SBP variation in American children and adolescents.