Effects of a Slow Linear Oxidative Fatigue Protocol on Hamstring Strength and Functional Performance

Date of Award

Winter 2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Human Movement Sciences

Committee Director

Bonnie L. Van Lunen

Committee Member

James A. Ornate

Committee Member

Michael Tamburello

Abstract

There are a number of etiological risk factors for hamstring injuries. The majority of hamstring injuries occur during an eccentric mechanism to decelerate the lower extremity and for protection of the knee joint. Residual hamstring weakness that is present after initial injury is observed by decreased eccentric strength and imbalances between the hamstring and quadriceps muscle strength relationship known as hamstring:quadriceps ratio. Functional performance measures are another tool utilized to identify deficits and readiness for return to activity after a lower extremity injury. Functional tests most often associated with hamstring performance include hop tests, agility tests, and vertical jumps. While both the role of hamstring strength and performance tests have been studied extensively with respect to injury risk in sports, the effects of these assessments in conjunction with fatigue is not well understood.

Fatigue is known to alter neuromuscular function, cause a reduction in muscle force, loss of coordination and motor control and have detrimental effects on lower extremity biomechanics. Several studies have shown greater risk of hamstring injury occurring during the latter stages of activity, when fatigue may be present. Limited studies have evaluated both hamstring strength and functional performance tasks in the presence of fatigue.

The purpose of this dissertation was to investigate the effects of a slow oxidative fatigue protocol on hamstring strength and functional performance tasks using three experiments. In experiment I, the aim was determine the effects of a slow linear oxidative fatigue protocol on hamstring strength and functional performance tasks in a group of healthy physically active individuals. Results revealed an increase in time to complete the six meter timed hop test (6MH) and a statistically significant increase in conventional I-IQ ratio at 60°/s post the fatigue protocol. There was no other strength or functional performance differences. In experiment II, the aim was to determine if any strength or functional performance task differences existed between individuals with history of hamstring injury and a healthy matched-control group following a Slow Linear Oxidative Fatigue Protocol. Findings revealed a statistically significant decrease in functional HQ ratio at 180°/s ratio and concentric hamstring strength at 240°/s post-fatigue. There were no other strength differences or functional performance differences. The purpose of experiment III was to evaluate eccentric hamstring strength and hamstring functional performance between the injured and non-injured side of those with a history of unilateral hamstring injury following the implementation of a fatigue protocol. There were no statistically significant differences between side and time for any of the strength and functional performance measures pre and post the fatigue protocol.

Overall, our studies revealed limited hamstring strength and functional performance deficits after our fatigue protocol for some of our measures. We believe our fatigue protocol may have been too robust for our patient population to fully complete to enable hamstring fatigue. As a result, type, level of fatigue and population needs to be considered when designing the most appropriate protocol to elicit hamstring fatigue.

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DOI

10.25777/0gs3-ek49

ISBN

9781321586848

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