BODY MASS INDEX AS A PREDICTOR OF VERTICAL POWER, AGILITY AND LOCAL MUSCULAR ENDURANCE IN SCHOOL -AGED GIRLS

<jats:p>Excess body mass in pediatric populations acts as a significant biomechanical constraint, potentially compromising the acquisition of fundamental motor skills and neuromuscular performance. Objective: This study aimed to examine the relationship between Body Mass Index (BMI) and specific motor performance indicators in school-aged girls, with a particular focus on the dissociated effect of body mass on core musculature. Methods: A cross-sectional study was conducted on 60 female students aged 8 to 10 years (9.2 ± 0.6 years). Somatic characteristics were assessed, and motor performance was evaluated using four standardized tests: 20m Coordination Test (agility), Counter Movement Jump (vertical power), 30s Sit-ups (abdominal endurance), and 30s Trunk Extensions (posterior chain endurance). Data normality was confirmed, and Pearson’s correlation coefficient (r) was used for analysis. Results: BMI acted as a significant negative predictor for all weight-bearing tasks. Strong correlations were observed for agility (r = 0.582, p &lt; .001) and vertical power (r = -0.495, p &lt; .001). The most severe penalty was found in abdominal endurance (r = -0.612, p &lt; .001), where BMI explained 37.5% of the performance variance. Conversely, no statistically significant correlation was found for the trunk extension test (p &gt; .05). Conclusion: Excess body mass imposes a significant mechanical constraint ("dead weight" effect) on vertical power and agility. Furthermore, BMI differentially affects local muscular endurance; while anterior chain performance is severely compromised, posterior chain function appears preserved, potentially due to the chronic functional loading of the erector spinae muscles required for postural stabilization in heavier children.</jats:p>