Date of Award

1998

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Communications, Health and Science

First Advisor

Dr Paul Sacco

Abstract

Investigations into the mediators of effort sensation have indicated that central mechanisms related to corollary discharges may be responsible for an increased sense of effort during fatiguing isometric exercise. The role for central mediators for sense of effort have been objectively demonstrated through use of contralateral limb matching tasks. Subjects diagnosed with chronic fatigue syndrome (CFS) often report prevalent fatigue associated with a greater sense of effort when involved in exercise. This study employed a fatiguing contralateral limb-matching task in order to determine if CFS subjects (n == 6) experienced an altered sense of effort associated with the task when compared to control group (n = 6). The task involved subjects performing an intermittent sub-maximal contraction in their reference (non-dominant) arm for a 45 minute period. Subjects attempted to match the force in their reference arm (30% MVC) with their dominant arm every minute, except for every fifth minute, when a maximal voluntary contraction (MVC) was performed in the reference arm. Associated electromyography (EMG), force, and rate of perceived exertion (RPE) were recorded on a regular basis. Results indicated that while there were no significant difference between groups for matching force, rmsEMG amplitude, and MVC force, there was a significant difference in reported RPE scores (P < 0.05) during the fatiguing task, as well as during baseline measurements. Elevated RPE scores, combined with trends indicating that a longer protocol may have produced a significant difference in matching force, provide evidence demonstrating thdt CFS subjects experienced a greater sense of effort relative to controls. This study demonstrates that the symptom of fatigue experienced in CFS may be better defined employing mediators for sense of effort than the regular application of a neurophysiological definition of fatigue concerned with the loss of force generating capacity.

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