Modeling the Association Between Hand Grip Strength and Physiological and Psychological Factors in School-Aged Children

Hand grip strength (HGS) is a key measure of upper limb muscular function, encompassing both hand and forearm strength. While extensively studied in older adults for its links to physical and cognitive health, HGS is also a valuable indicator of fine motor skills and physical capacity in adolescents. This study aimed to develop a predictive model of adolescent HGS using anthropometric variables to identify those at risk of future health issues. Sociodemographic data, Body Max Index (BMI), and body fat percentage were collected during Physical Education classes. HGS was measured twice using the dominant arm, with the best result recorded. Additional data from the Course Navette test, the Physical Activity and Leisure Motivation Scale (PALMS), and the International Physical Activity Questionnaire (IPAQ) were also collected. A nested 10-fold cross-validation pipeline was used, incorporating Boruta feature selection, ElasticNet regression tuning, and model evaluation with MAE, RMSE, R², and bootstrapped confidence intervals.<b> </b>The sample included 867 secondary school students (mean age = 14.03 ± 1.19 years; 53.9% boys). The model showed good predictive performance: MAE = 3.76 (0.29), RMSE = 4.73 (0.36), R² = 0.48 (0.08), and Average Normalized MAE = 9.90%. Significant predictors included Age (b = 1.86), Sex (b = -1.03), BMI (b = 4.16), Body Fat (b = -3.94), and Navette Stages (b = 1.06). This predictive model effectively identifies adolescents at risk of low muscular strength and highlights the central role of anthropometric factors in strength assessment. When integrated with physiological and psychological parameters, these factors could significantly contribute to improving adolescent health.