Term of Award

Winter 2024

Degree Name

Master of Science in Kinesiology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Health Sciences and Kinesiology

Committee Chair

Nicholas Siekirk

Committee Member 1

Jody Langdon

Committee Member 2

Li Li

Abstract

Isotonic hamstring exercises are employed to mitigate the risk of a future hamstring strain and after strain, incorporated into return-to-play protocols. However, research has negated leg dominance's influence on muscle recruitment and exercise form. Therefore, the purpose of this study was to compare muscle recruitment between the dominant (DOM) and non-dominant (nonDOM) during prone hamstring exercise (PHSE) variations. METHODS: Twenty trained participants aged 18 – 33 (M = 23 years, SD = 3 years) completed familiarization and experimental protocols > 72 hours apart. Participants underwent four PHSE variations that differed by load type (barbell vs. dumbbell), exercise strategy (bilateral vs. unilateral), and exercise tempos (fast vs. slow). Mean electromyography (mEMG) of the gluteus maximus (Gmax), biceps femoris (BF), vastus lateralis (VL), and gastrocnemius (GS) were recorded bilaterally, normalized to maximum voluntary contractions (MVC), and reported as a percentage (%MVC) for the dominant and non-dominant legs, as determined by the Waterloo Footed Questionnaire. Separated linear mixed models examined the eccentric (ECC) and concentric (CON) mEMG for 3-way interaction between side (DOM vs nonDOM), variation (barbell bilateral strategy vs. dumbbell unilateral strategy), and eccentric tempo (2-second fast vs. 4-second slow) while controlling for baseline isokinetic strength. RESULTS: No three-way nor 2-way interactions were detected (p > 0.122). Main effects of the side were detected in all recorded muscles (ps ps < 0.027). Conversely, the nonDOM’s BF EMG was greater than DOM (ps < 0.001). Main effects of tempo were limited to the GS and VL where fast tempo produced greater mEMG (p < 0.014). CONCLUSION: We observed biased recruitment in the nonDOM’s BF and the DOMs Gmax, VL, and GS across PHSE variations despite no differences in knee active range of motion or isokinetic, isometric strength assessment. Further investigations are warranted to decipher whether this recruitment bias is a compensatory motor strategy to adhere to task goals and whether this recruitment bias is observed with increased external exercise loads. Furthermore, whether this recruitment bias constitutes a risk for a hamstring strain is yet to be determined.

OCLC Number

1478262330

Research Data and Supplementary Material

Yes

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