Exploring the role of different intensities of physical activity on fitness parameters in 9–11-year-old children: a framework for potential innovation of the physical education curriculum

Background and Study Aim. Although physical activity (PA) is an important determinant of physical fitness (PF) in children, studies have rarely examined the associations between PA and PF in early school-age children within narrow age spans. The aim of this study was to evaluate the associations between different intensities of PA and various indices of PF in children aged 9 -11 years. Material and Methods. The participants were 121 children aged 9 - 11 years (49 girls) who were tested for PF (anthropometrics, aerobic endurance, upper body and abdominal strength, jumping power, mobility and flexibility), and the PA was directly measured via GeneActiv triaxial accelerometers. A t test was used to define differences between sexes, while Pearson’s correlations between PA variables and PF indices and multiple regressions for PF criteria were used to calculate sex stratification. Results. Compared with girls, boys achieved better results in terms of jumping power capacity, upper body strength, and aerobic endurance, and they had a higher number of steps taken per day, and a higher amount of vigorous PA per day (all p < 0.05). The girls achieved better results in terms of flexibility and mobility. Correlations between PA-intensities and PF were weak to moderate. Multiple regression calculations revealed that vigorous PA was a significant predictor of jumping power, upper body strength, and aerobic endurance in boys (16%, 20%, and 13% of the explained variance, respectively) and jumping power in girls (18% of the explained variance). Moderate PA was a significant partial regressor of aerobic endurance in girls (13% of the explained variance). Conclusions. Tailoring physical-education curricula to gender-specific PA responses and expanding PF assessments can enhance student engagement, optimize fitness outcomes, and improve the overall effectiveness of physical education programs.