The Relationship Between Nutritional Status and Muscular Endurance in Early School-Aged Children

Background/Objectives: Early school age is a critical period for monitoring nutritional status and physical fitness to promote health and prevent obesity. This study aimed to determine nutritional status and muscular endurance in children aged 7–10 years and to examine differences by age and sex. Additionally, associations between anthropometric characteristics and muscular endurance were assessed, emphasizing comparisons between raw anthropometric measures and derived indices (BMI, WHR, WHtR). Methods: A cross-sectional study was conducted on 375 healthy children (184 boys, 191 girls) aged 7–10 years from Primorje, Gorski Kotar County, Croatia. Anthropometric measures included height, weight, waist circumference, and hip circumference, and muscular endurance was assessed via pull-up hold, 30-second sit-up, plank-to-failure, and squat-to-failure tests. Age and sex differences were analysed using MANOVA/ANOVA, and associations between anthropometric measures and endurance outcomes were examined using ANCOVA. Results: Age was the strongest predictor of performance across all endurance tests (p< .001), explaining 5.4–12.7% of variance, with the largest effect in the pull-up hold test. Sex differences were significant only at age 7, with boys performing better in sit-up, pull-up hold, and plank tests (p≤.039). Raw anthropometric measures were weak predictors after adjusting for age, whereas derived indices were more informative. WHtR was negatively associated with performance in the pull-up hold test at age 9 (p=.031) and the 30-second sit-up test at age 10 (p=.040). Conclusions: Age is a key determinant of muscular endurance, whereas a higher WHtR is associated with poorer performance in body-weight endurance tasks.