Lower-limb-muscle activation stabilizes frontal and sagittal knee alignment during a static lunge task

Abstract

[Purpose] The purpose of this study was to identify muscle activities required to stabilize knee alignment between Knee-in and Neutral groups during a static lunge task.

[Subjects and Methods] Twenty male subjects who joined sports requiring deceleration movements were included. Participants who had knee valgus alignment which is called “knee-in” were designated as the Knee-in group and others were assigned to the Neutral group, based on knee alignment during single-leg squats. Hip and thigh muscle activities were analyzed during a lunge task with a neutral knee position in the frontal plane, and these activities were compared between the Knee-in and Neutral groups. In the Neutral group, muscle activities around the shank were analyzed in the anterior or posterior weight-bearing positions.

[Results] There were no significant differences in the hip or thigh muscle activities between the Knee-in and Neutral groups. Activities of the gastrocnemius, soleus, and long peroneal muscle were greater during anterior weight-bearing position (p = 0.008).

[Conclusion] Muscle activities of the hip and posterior thigh do not seem to keep the knee neutrally in the frontal plane. Anterior position of weight-bearing increases muscle activity of the posterior shank and may stabilize sagittal knee alignment.