Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
from September 2014
©Journal of Sports Science and Medicine (2005) 04, 463 - 471

Research article
Reliability of Physiological, Psychological and Cognitive Variables in Chronic Fatigue Syndrome and the Role of Graded Exercise
Karen E. Wallman , Alan R. Morton, Carmel Goodman, Robert Grove
Author Information
School of Human Movement and Exercise Science, The University of Western Australia, Crawely, Western Australia

Karen E. Wallman
‚úČ School of Human Movement and Exercise Sciences, the University of Western Australia, Crawley, Western Australia
Publish Date
Received: 22-03-2005
Accepted: 16-09-2005
Published (online): 01-12-2005
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The objective of this study was to assess variability in symptoms and physical capabilities in chronic fatigue syndrome (CFS) participants both before and after a graded exercise intervention. Sixty-one CFS subjects participated in a 12-week randomized controlled trial of either graded exercise (n =32) or relaxation/stretching therapy (n = 29). Specific physiological, psychological and cognitive variables were assessed once weekly over a four-week period both prior to and after the intervention period. All scores were assessed for reliability using an intraclass correlation coefficient (ICC). Apart from mental and physical fatigue, baseline ICC scores for all variables assessed were moderately to highly reliable, indicating minimal variability. Baseline scores for mental and physical fatigue were of questionable reliability, indicating a fluctuating nature to these symptoms (R1 = 0.64 and 0.60, respectively). Variability in scores for mental fatigue was reduced after graded exercise to an acceptable classification (R1 = 0.76). Results from this study support a variable nature to the symptoms of mental and physical fatigue only. Consequently, in order to more accurately report the nature of mental and physical fatigue in CFS, future studies should consider using repeated-measures analysis when assessing these symptoms. Graded exercise resulted in the reclassification of scores for mental fatigue from questionable to acceptable reliability.

Key words: Fluctuating symptoms, repeated measures, single session measures, repeatability

           Key Points
  • Chronic fatigue syndrome sufferers often report a fluctuating nature to their symptoms and physical capabilities.
  • Weekly assessment over a four-week period of psychological, physiological and cognitive variables demonstrated that only mental and physical fatigues were of questionable reliability.
  • A 12-week graded exercise intervention resulted in the improvement of ICC scores for mental fatigue to that of acceptable reliability.
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