Influence of head and neck extension on single-leg landing

Abstract

[Purpose] To clarify influences of neck and head extension on single-leg landing. [Subjects and Methods] Thirty-one healthy young women (average age, 20.1 years old) participated in this study. Single-leg landings from a 30 cm-height platform were performed by all of the participants with the head and neck extended and in the neutral position. The maximum knee flexion, valgus angles, and anteflexion, retroflexion, and lateral bending angles of the trunk, and the landing position of the two postures were measured and compared. [Results] The knee valgus angle was significantly greater in the neck and head extended posture than in the neutral posture. There were no significant differences in knee flexion, anteflexion, retroflexion, lateral bending of the trunk, or landing position. [Conclusion] Single-leg landing with the neck and head extended is associated with an increase in knee valgus angle. This suggests that neck and head extension is one of the causes of non-contact anterior cruciate ligament injury.