Author(s): JURAS, G., SLOMKA, K., BRACHMAN, A., MICHALSKA, J., ZAK, M., MASZCZYK, A., ZWIERZCHOWSKA, A., Institution: AKADEMIA WYCHOWANIA FIZYCZNEGO IM. JERZEGO KUKUCZKI W KATOWICACH, Country: POLAND, Abstract-ID: 2543

INTRODUCTION:
Postural control is one of the key prerequisites for engaging in various forms of physical activity, and may serve as a sensitive marker of early motor deficits during physical development. Lower limb asymmetry has been associated with increased injury risk and impaired functional performance, yet normative developmental data for pediatric populations remain scarce. The aim of this study was to analyze lower limb asymmetry (dominant vs. non-dominant) in postural control across ontogenesis in a population of children and adolescents from the Upper Silesia region in Poland.
METHODS:
A total of 1339 participants aged 7-17 years were included. Participants were divided into four developmental age groups: 7-9 years (stable pre-pubertal growth phase), 10-12 years (early pubertal changes), 13-15 years (pubertal growth spurt), and 16-17 years (post-pubertal stabilization). The Y Balance Test (YBT) was performed, measuring lower extremity reach distances in the anterior-posterior (AP) and medial-lateral (ML) directions. Asymmetry was calculated using the formula: Asymmetry Index = [(ND - D) / (0.5 x (D + ND))] x 100, where D = dominant limb and ND = non-dominant limb. Statistical analysis included descriptive statistics, percentile calculations (3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th), and Pearson correlation coefficients. Significance levels were set at p<0.05, p<0.01, and p<0.001.
RESULTS:
Asymmetry indices showed a clear developmental trend toward symmetry, with mean values approaching zero with increasing age. Younger children (7-9 years) exhibited greater asymmetries (mean: -2.14% to -3.58%), with negative values indicating poorer non-dominant limb performance. By age 16-17, asymmetry indices approached zero or became slightly positive (0.15% to 0.61%), suggesting functional symmetry or mild non-dominant limb superiority in late adolescence, likely reflecting bilateral neuromuscular refinement during ontogenesis. ML asymmetries were consistently larger than AP asymmetries across all age groups, indicating that lateral reach tasks require greater neuromuscular control. Sex differences in asymmetry were minimal, with males showing slightly greater variability in most age groups.
CONCLUSION:
Lower limb asymmetry systematically decreases with age, reaching functional symmetry levels in late adolescence (16-17 years). These findings underscore the need for age-specific clinical thresholds rather than universal cut-off values when assessing asymmetry in pediatric populations. The results support the implementation of postural control screening in schools, sports programs, and clinical settings. Interventions should aim not only at improving functional performance but also at injury prevention. Future research should establish developmental reference values to facilitate early identification of motor deficits.