Kikuchi R, et al. - Since there has been a progress in the number of non-specific low back pain (LBP), therefore, through a cohort analysis of a 6-year birth cohort annual survey of students who were followed from the fourth to sixth grades of elementary school through the first to third grades of junior high school, the researchers assessed gender variation in the relationship between extracurricular sports activities (ECSA) and LBP in children and adolescents. Only in third grades of junior high school (J3) among boys, ECSA was significantly correlated with LBP. In fifth grade of elementary school (E5), E6, and J3, ECSA was significantly correlated with LBP amongst girls. The population attributable fraction (PAF) was same in all grades among boys, whereas among girls, the PAF varied and was significantly greater in girls in comparison in boys in grade E5 and E6. Hence, girls were more prone to ECSA-related LBP, especially in grades E5 and E6, however, there was a correlation between ECSA and LBP in both boys and girls.