Date of Award

2018

Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Advisor

Thomas Mohr

Keywords

Anterior Cruiciate Ligament Injuries; Electromyography; Hamstring Muscles -- physiology; Quadriceps Muscle -- physiology

Abstract

Background and Purpose. The purpose of this pilot study was to see if there was a difference in amount of electromyographic (EMG) activity in the quadriceps (vastus medialis and vastus lateralis) compared to amount of EMG activity in the hamstrings (biceps femoris and semitendinosus) in active male and female subjects during vertical jumping and landing. In addition, we looked at the amount of knee flexion that occurred in the male and female subjects shortly after landing from a vertical jump.

Methods EMG activity was recorded using a Noraxon TeleMyo DTS telemetry unit with a sampling rate of 1 kHz. EMG data was recorded during vertical jumping and landing. EMG activity in two quadriceps muscles (vastus medialis and vastus lateralis) and two hamstring muscles (biceps femoris and semitendinosus) were monitored during the experiment. The subject was also captured on video using the NiNox 125/250 FPS camera system. Subjects consisted of two male and two female athletes in good physical condition with no previous knee pathologies.

Results Differences were found in the quadriceps to hamstring ratio when comparing female to male participants in both single jump (Female 4.42:1, Male 2.38:1) and triple jump landing (Female 5.46:1, Male 1.90:1). Females generally showed higher percent of maximal voluntary contraction in the quadriceps than the males when compared for both jumps. Remarkable differences in knee flexion upon landing were not found between genders in either test.

Conclusion The results of this study showed quadriceps dominance in females as compared to males when landing from a jump. Previous studies have theorized that this level of dominance creates tensile force on the ACL, leading to increased incidence of ACL tears. Strength training focused on hamstring activation with a proper quadriceps to hamstring muscles ratio should be implemented when preventing ACL injuries especially in the female population. Further research is needed to confirm these conclusions and demonstrate clinical relevance.

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