Fitness, waist circumference and their association with future blood pressure in youth: The UP&DOWN Longitudinal Study

Abstract Objectives The aim was to determine the independent associations of muscular fitness (MF), cardiorespiratory fitness (CRF) and waist circumference (WC) with blood pressure (BP) levels over 2 years in children and adolescents. Methods 1089 children (517 females) and 787 adolescents (378 females) with complete data on fitness, WC and BP (systolic [SBP] and diastolic [DBP]) were included. Upper MF was assessed through the handgrip strength test, and lower MF using the standing long jump test. The 20-m shuttle run test was used to assess CRF. WC was obtained following standardized methods. Different regression models were fitted by introducing fitness and WC at baseline and their changes as exposures and BP at follow-up and their changes as outcomes. Results WC at baseline was positively and independently associated with each BP variable at follow-up in children and adolescents (β = 0.094–0.260; p ≤ 0.05), and CRF was negatively associated with DBP in adolescents (β = −0.096; p = 0.034). WC changes were associated with BP variables 2 years later in children (β = 0.121–0.142; p  Conclusions WC, but neither MF nor CRF, is independently associated with BP and its changes over 2 years. The attainment or maintenance of optimal fatness levels in the pediatric population should be highly encouraged for the prevention of future hypertension.