Sex- and Age-Specific Differences in Single-Leg Balance Performance Among Young Competitive Ski Racers: A Cross-Sectional Study.

PURPOSE: This study examined sex- and age-specific differences in single-leg balance performance among young competitive alpine ski racers to better understand developmental trajectories of postural control and their implications for individualized training and performance development. METHODS: A total of 264 elite youth ski racers (114 females; aged 14-19 y) were tested annually between 2016 and 2022 performing a single-leg balance task on the MFT Challenge Disc 2.0. Balance performance was assessed separately for the left and right leg, and a Limb Symmetry Index was calculated to quantify interlimb asymmetry. Linear mixed-effects models evaluated the effects of sex, age, and their interaction on balance outcomes, with height included as a covariate. RESULTS: Female athletes consistently demonstrated superior single-leg balance performance compared with males across all age groups (β ≈ 0.4, P < .001). Balance ability improved significantly with age (β ≈ -0.17, P < .001) for both sexes, indicating developmental progression. No sex-by-age interaction was observed for either leg, suggesting parallel improvement trajectories. Limb Symmetry Index decreased with age (P < .001), reflecting reduced asymmetry, and showed a modest sex-by-age interaction, with females exhibiting greater improvements. CONCLUSION: Female youth ski racers outperformed males in single-leg balance, likely due to anatomical and maturational factors, such as a lower center of mass and earlier pubertal onset. Balance improved with increasing age, emphasizing the combined influence of neuromuscular development and cumulative training exposure. These findings highlight the importance of incorporating sex- and age-specific balance training in alpine skiing to optimize performance.