Date of Award


Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)


Physical Therapy

First Advisor

Mark Romanick


Anterior Cruciate Ligament Injuries -- etiology; Risk Factors


The anterior cruciate ligament (ACL) in the knee is often sprained or torn in injuries resulting from jumping, cutting, or hyperextension of the knee. When the knee is put under a valgus, varus, or rotatory stress it can put strain on the ACL. Lower extremity motor control can help control the amount of varus and valgus stress on the knee. Lower extremity muscle control is involved with preventing this stress and resulting injuries. This study was performed to determine whether the position of the foot (neutral, supination, and pronation) has an effect on lower extremity muscle activity during single-leg squats.

Six muscles were measured with EMG while the subjects performed single-leg squats with the foot in various subtalar positions. The muscles measured were gluteus maximus, gluteus medius, biceps femoris, rectus femoris, lateral gastrocnemius, and tibialis anterior.

The study produced significant differences in EMG activity for the gluteus maximus, lateral gastrocnemius, and biceps femoris. However, more research needs to be performed to prove if foot position has significant influence on lower extremity muscle activity and how it affects the ACL.