Associations Between Segmental Upper-Extremity Isometric Strength and Shuttlecock Velocity in Young Badminton Players.

Background and Objectives: Upper-extremity strength is considered an important contributor to badminton stroke performance; however, the independent contributions of specific muscle groups to shuttlecock velocity in young players remain unclear. This study investigated the associations between segmental upper-extremity isometric strength and shuttlecock velocity in young badminton players. Methods: Twenty-four competitive U11 badminton players (12 males and 12 females; mean age, 10 years) participated in this cross-sectional study. Handgrip and segmental upper-extremity isometric strength (elbow, shoulder, and wrist muscle groups) were assessed using dynamometry. Shuttlecock velocity during a badminton smash was measured using a radar gun. Results: Shuttlecock velocity was positively correlated with all measured upper-extremity strength variables (r = 0.408-0.704, all p < 0.05). After adjustment for sex and upper-limb length, only shoulder extension (r = 0.529, p = 0.011), shoulder flexion (r = 0.557, p = 0.007), shoulder external rotation (r = 0.430, p = 0.046), and shoulder internal rotation strength (r = 0.495, p = 0.019) remained significantly associated with shuttlecock velocity. Multiple regression analyses confirmed these shoulder-specific strength measures as independent predictors of shuttlecock velocity (β = 0.343-0.468, all p < 0.05), explaining 57.2-63.8% of the adjusted variance. Conclusions: Although shuttlecock velocity was initially associated with all upper-extremity strength measures, only shoulder-specific strength remained associated with performance after adjustment for sex and upper-limb length. These exploratory findings suggest that shoulder strength may represent a relevant physical correlate of badminton smash performance in young athletes; however, confirmation in larger, adequately powered studies is required.