The Influence of Coronal Strike Stance Angle on Kicking Mechanics in Adolescent Female Soccer Players.

Background: Anterior cruciate ligament (ACL) tears are one of the leading injuries in soccer players, especially among female athletes. Prior research has investigated risk factors associated with the swing limb during a soccer kick, but limited research has focused on biomechanical risk factors of the stance limb that may contribute to elevated injury risk when kicking. Hypothesis/Purpose: The purpose of this study was to quantify the relationship between strike stance angle (SSA) and lower extremity kinematics and kinetics during a soccer kick. SSA is the coronal angle created by the hip joint center to the ankle joint center of the stance limb from vertical. It was hypothesized that a greater SSA would be correlated to greater biomechanical risk factors and that correlated findings would differ by dominance. Study Design: Cross-sectional study. Methods: Nineteen healthy female soccer players (15.2±0.9 years) were tested performing a soccer kick on each limb in a motion capture laboratory. Kinematics and kinetics from the stance limb were captured at ball contact. Spearman correlations were performed to identify significant associations with SSA. Results: During the stance limb-dominant kick, greater ankle dorsiflexion (r=0.72, p=0.018) was associated with greater SSA. Non-significant trends towards increased hip adduction and knee flexion were also observed. For the stance-limb-non-dominant kick, knee valgus moment (r=-0.81, p=0.002) and external knee rotation moment (r=-0.66, p=0.038) were also associated with greater SSA. A non-significant correlation was also observed between increased knee flexion and greater SSA. Conclusions: Altered hip mechanics and knee loading risk factors were associated with greater SSA, and associations differed by limb dominance. Additional research is needed to better define the relationship between SSA and lower extremity injury risk of healthy youth soccer players and to explore the potential impact on injury prevention. Level of Evidence: Level 3.