Relationship of lower extremity alignment during the wall squat and single-leg jump: assessment of single-leg landing using three-dimensional motion analysis

[Purpose] The purpose of this study was to evaluate the relationship between malalignment and lower-extremity injury and to determine the optimal dynamic alignment of the lower extremity with wall squats. [Subjects and Methods] Healthy individuals from one therapy school were enrolled and assigned to a wall squat normal or abnormal group based on their forms during wall squats. The abnormal group was found to be more prone to lower-extremity injury on three-dimensional motion analysis. Eight students from each group were randomly chosen for the study. The effects of single-leg landing movements were assessed using three-dimensional motion analysis. [Results] In the sagittal plane, significant flexion of the hip and knee joints occurred 0.02 and 0.04 seconds after initial foot contact with the ground in the normal and abnormal groups, respectively. In the frontal plane, significant adduction of the hip joint occurred at 0.07 seconds in the abnormal group. [Conclusion] The abnormal group tended to display later flexion of the hip and knee joints and narrower hip, knee, and ankle range of motion than the normal group, suggesting that dynamic alignment of the lower extremity in the abnormal group likely made them susceptible to injury.