Author ORCID Identifier

https://orcid.org/0000-0002-5538-4326

Year of Publication

2020

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Health Sciences

Department

Rehabilitation Sciences

First Advisor

Dr. Tim L. Uhl

Second Advisor

Dr. Arthur J. Nitz

Abstract

Load carriage is a primary source for injury occurrence among military personnel and recreational hikers affecting all body areas. The shoulder ranks as the second or third most common site of injuries among military personnel. Many studies report that elevations in self-reported fatigue, soreness, and discomfort in the shoulders accompany the load carriage. Almost 50% of military personnel experienced a load carriage injury during the first episode of training, and 75% of those injured suffered a second injury during their career. The goal of this research project is to investigate the components associated with load carriage shoulder symptoms to determine which factor is a more substantial contributor to the cause of shoulder pain and injury.

The first purpose of this dissertation was to investigate the effect of load carriage on shoulder strength and endurance, nerve amplitude and latency, and shooting accuracy. Experimental comparison between the neuromuscular functions before and after the load carriage of 20.5 kg was investigated in the first and second study. The second purpose was to determine the recovery time needed for the neuromuscular measures that were affected with load carriage task.

The first study demonstrated that load carriage caused a significant decrement in shoulder strength, shoulder endurance, and nerve amplitude. The second study demonstrated that the load carriage task resulted in decreased strength, yet recovered in thirty minutes. Similarly, a decrement in nerve amplitude resulted but recovered in five minutes. The results of these studies suggest that load carriage mainly causes physical fatigue which affects shoulder strength. Fatigue could compromise the ability to perform overhead physical tasks if sufficient recovery time is not permitted.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.253

Funding Information

Partly supported by the Endowed University Professor in Health Sciences Funds, April 2018 - April 2019

Available for download on Monday, May 23, 2022

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