Date of Award

5-2020

Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Advisor

Thomas Mohr

Abstract

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

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

Results. Differences were found in the quadriceps to hamstrings ratio when comparing female to male participants in both single jump (Female 4.31:1, Male 2.41:1) and triple jump landing (Female 3.56:1, Male 2.0:1). Females generally showed higher percent of maximal voluntary contraction in the quadriceps than the males when compared for both jumps. The amount of knee flexion upon landing were similar between genders in both the single and triple jump/landing 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 AGL, leading to increased incidence of AGL tears. Strength training focused on hamstring activation with a proper quadriceps to hamstrings ratio should be implemented when preventing AGL injuries especially in the female population. Further research is needed to confirm these conclusions and demonstrate clinical relevance.

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