The mediating role of adiposity in the longitudinal association between cardiorespiratory fitness and blood pressure in adolescents: LabMed cohort study

Abstract

The aim of this prospective cohort study was to examine whether the association between the cardiorespiratory fitness (CRF) at baseline and blood pressure (BP) at follow-up is mediated by adiposity in adolescents. The sample comprised 734 adolescents (349 girls) aged 12-18years from the LabMed Physical Activity Cohort Study. The variables of interest were measured in 2011 (baseline) and in 2013 (2-year follow-up). CRF was assessed by the 20-m shuttle run test. Body mass index, waist circumference, body fat percentage, pubertal status and resting BP were assessed according to standard procedures. Boot-strapped mediation procedures were performed, and indirect effects (IE) with confidence intervals (CI) not including zero were considered statistically significant. After adjusting for potential confounders, body mass index acted as a mediator of the relationship between CRF and systolic BP (IE=-0. 023; CI=-0.039; -0.009), pulse pressure (IE=-0.023; CI=-0.034; -0.012) and rate product pressure (IE=-2.839; CI=-5.329; -0.340). Similar results were obtained for waist circumference as mediator for systolic BP (IE=-0.019; CI=-0.033; -0.005), pulse pressure (IE=-0.017; CI=-0.028; -0.007) and rate product pressure (IE=-3.793; CI=-6.097; -1.689). Likewise, body fat percentage mediated the association for: systolic BP (IE=-0.029; CI=-0.048; -0.010), pulse pressure (IE=-0.027; CI=-0.041; -0.013) and rate product pressure (IE=-4.280; CI=-7.488; -1.264). Adiposity mediated the association between CRF and BP in adolescents. Therefore, both optimal CRF and adiposity levels are important to maintain normal BP ranges throughout adolescence.