Fitness, body composition and metabolic syndrome score in children and adolescents: The UP&DOWN study

Abstract Purpose: We aimed to analyse the longitudinal association between physical fitness (PF) and body composition (BC) with metabolic syndrome score (MetS) in children and adolescents, and to elucidate whether the association between PF and MetS differs when using relativized or absolute fitness variables. Methods: A total of 188 children (86 females) and 195 adolescents (97 females) were included. Cardiorespiratory fitness (CRF) was determined by the 20-m shuttle run test and muscular fitness (MF) was determined by hand grip and standing long jump tests. Height and weight were measured, and body mass index (kg/m 2 ) was calculated. Triceps and subscapular skinfolds were assessed to compute body fat percentage. MetS was computed from: waist circumference, systolic blood pressure, triglycerides, high-density lipoprotein cholesterol and glucose levels. Results : Relative CRF was longitudinally and negatively associated with MetS in female children (β=-0.031,p=0.025), while absolute CRF was positively associated with MetS in male children and adolescents (β=0.000,p<0.05). Relative upper and lower-body MF were longitudinally and negatively associated with MetS in female adolescents (β=-1.347,β=-0.005,p<0.05), while absolute lower-body MF was positively associated with MetS in male children (β=0.000,p=0.019). BC was longitudinally and positive associated with MetS in male children (β-ranging from 0.011-0.055,all p<0.05) and male adolescents (β-ranging from 0.011-0.046,all p<0.05). Conclusion: BC is more strongly associated with MetS than PF in children and adolescents. An optimal body weight status should be considered the main objective of health promoting programs at childhood and adolescence. Furthermore, the way of expressing the fitness variables determines the direction of the association with MetS.