Date of Award

2013

Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Advisor

Mark Romanick

Abstract

Purpose: There is a high prevalence of ACL injury in the athletic populations, which can carry out short and long term debilitative effects. Most ACL injuries involve minimal to no contact and female athletes sustain a two to eightfold greater rate of injury than male athletes. Not much research has been conducted to see if foot position directly affects the lower extremity muscles, which could result in altered biomechanics at the knee.

Methods: Twelve subjects 18-30 years old participated in the study. EMG analysis measured differences of muscle contractions for the gluteus maximus, gluteus medius, biceps femoris, rectus femoris, lateral gastrocnemius and anterior tibialis muscles in varied foot positions to include: neutral (control), pronation 5o, pronation 10o, supination 5o, and supination 10o.

Results: When comparing the baseline single leg squat to each of the four test positions (pronation 5o, pronation 10o, supination 5o, and supination 10o) the only significance found was in the anterior tibialis muscle (p< 0.05). No significant difference was found in the gluteus maximus, gluteus medius, biceps femoris, rectus femoris, or lateral gastrocnemius muscles in the tested foot positions.

Conclusions: Results of this study show that only the anterior tibialis muscle is affected according to foot position during a single-leg squat. This study suggests that foot position may not have an effect on muscles of the lower extremity and does not play a major role in non-contact ACL injuries. Many other elements may have affected the results and should be investigated more thoroughly with larger numbers of participants to be more confident of foot position’s influence on muscle activity in the lower extremity and role as a possible cause of ACL injury.

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