Sex and Limb Dominance Differences in Postural Control Performance of Young Adults: A Third-Order Polynomial Decay Approach

This study systematically evaluated postural control performance on dominant and non-dominant sides in young adults of different sexes using a Third-Order Polynomial Decay fitting method combined with time-domain stability features. A total of 126 participants (66 males, 60 females) performed single-leg landing tasks, during which ground reaction forces (GRF) and center of pressure (COP) data were collected using a Kistler 3D force platform and Bioware acquisition system. Dynamic stability times in the anterior–posterior, medial–lateral, and vertical directions were calculated with polynomial fitting, and additional time-domain measures were used to assess static and dynamic stability. Results showed that on the non-dominant side, participants exhibited significantly longer dynamic stability times (p = 0.015), greater root mean square distance (p = 0.005), and longer total sway path (p = 0.005) in the anterior–posterior direction compared with the dominant side. Significant sex differences were also found in vertical stability index (p = 0.044), dynamic stability index (p = 0.047), total sway path (p < 0.001), anterior–posterior sway path (p = 0.001), and medial–lateral sway path (p < 0.001). In conclusion, the dominant limb demonstrated superior stability, males showed better static control, and females displayed greater dynamic stability, underscoring the importance of targeted non-dominant training and sex-specific balance strategies.