Upper-Limb Dynamic Stability and Functional Symmetry in Experienced Taekwon-Do Athletes

Combat sports are characterized by sport-specific asymmetrical movement patterns that may influence neuromuscular control, functional stability, and injury risk. Although lower-limb asymmetry has been widely investigated in taekwon-do experienced ITF taekwon-do practitioners, upper-limb functional symmetry remains insufficiently explored. Sixteen experienced male ITF taekwon-do practitioners underwent assessment of hand grip strength and upper-limb dynamic stability using the Upper Quarter Y-Balance Test (UQYBT). Reach distances in anterior (AP), posteromedial (PM), and posterolateral (PL) directions were analyzed together with composite symmetry indices. Inter-limb differences were evaluated using paired Student’s t-tests, and associations between strength and dynamic stability variables were examined using Pearson’s correlations. Significant inter-limb asymmetry was observed only in the posteromedial (PM) UQYBT direction, with higher values for the left upper limb (p < 0.001; dz = 1.34). No significant inter-limb differences were observed for hand grip strength, anterior reach distance, posterolateral reach distance, or composite index values. Correlation analyses demonstrated weak-to-moderate and statistically non-significant relationships between hand grip strength and dynamic stability variables. Experienced taekwon-do athletes demonstrate movement-specific upper-limb asymmetry while maintaining relatively symmetrical overall dynamic stability and grip strength. The findings further suggest that upper-limb dynamic stability may depend more strongly on neuromuscular coordination and sport-specific motor control than on maximal grip strength alone. These findings suggest that asymmetry in taekwon-do may reflect a potential sport-specific adaptation rather than generalized neuromuscular dysfunction.