Cardiorespiratory fitness (CRF) has been shown to be linked with all-cause and cause-specific mortality in both adults and adolescents. 1,2 Furthermore, CRF has been shown to be associated with various metabolic risk factors and health, such as hypertension, type 2-diabetes, and obesity both in adolescence and adulthood. 3,4 Previous studies from around the world have indicated that during the last few decades children's and adolescents' physical activity engagement has decreased 5,6 while overweight and sedentary behavior have increased. 7,8 These changes are potential reasons for the downward trend in CRF in adolescent populations. 9 In light of previous findings