Date of Award

1996

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Science, Technology and Engineering

First Advisor

Dr Paul Sacco

Abstract

Fatigue associated with activity is a normal response, seeking to prevent damage or conserve energy. Some individuals show heightened fatigue responses with no distinct aetiology. In chronic fatigue syndrome (CFS), peripheral fatigue mechanisms display no apparent abnormalities, indicating some central mechanism. Transcranial magnetic stimulation (TMS) was used to compare force, perceived exertion, electromyogram response, motor evoked potentials (MEP) and silent periods (SP) following stimulation in normal and chronic fatigue groups. Participants (n=l2) were physically matched and performed a sustained sub-maximal (20% of MVC) isometric contraction of the elbow flexors. There were no significant differences (p < 0.05) in elbow flexor strength or time to reach fatigue. CFS participants showed a significant difference in perception of effort at outset. Differences were also noted in MEP amplitude and SP duration (p<0.05). Controls showed an increase in MEP amplitude and SP duration during the fatigue protocol, while CFS group showed no change. The central nervous system responses to fatigue in CPS group appears abnormal. This confirmed previous studies indicating a change in the normal inhibitory response. While specific sites for such disruptions are not indicated, findings support literature in suggesting that a disruption to responses of inhibitory interneurones may be responsible. This confirms that a clear and distinct pathology is associated with the CFS. Recommendations for further research into the process of central fatigue are given.

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