elevated body mass index and body fat percentage are associated with decreased physical fitness in soccer players aged 12–14 years

purpose adolescents are in increased risk for the development of obesity, while sport has been suggested as an effective means against adolescent obesity. the objectives of this study were to examine (a) the prevalence of overweightness/obesity, (b) the relationship between body mass index (bmi) and body fat percent (bf), and (c) the association between bmi, bf and physical fitness in adolescent soccer players. methods members (n=136, aged 13.1±0.6 yr) of competitive soccer clubs were examined for physical and physiological characteristics. results based on international bmi cut-off points, 19.9% (n=27) of participants were classified as overweight. bmi was highly correlated with bf (r=0.77, p<0.001). bmi and bf were in inverse relationship with aerobic power (r= − 0.29, p<0.001; r= − 0.44, p<0.001, respectively), maximal anaerobic power (r= − 0.23, p=0.009; r= − 0.47, p<0.001) and local muscular endurance (r= − 0.36, p<0.001; r= − 0.67, p<0.001). conclusions the strong relationship between bmi and bf suggest the further use of bmi in adolescent soccer players. the findings confirmed previous observations in the general population about the negative effect of overweight and fatness on physical fitness. the prevalence of overweightness among participants was similar with what is observed in general population. therefore, sport participation cannot guarantee physiological body mass and body composition, and it is necessary to prescribe exercise targeting body mass and fat control.