title: Reliability of physiological, psychological, and cognitive variables in chronic fatigue syndrome.
abstract: The purpose of this study was to assess the reliability of specific physiological, psychological, and cognitive variables in 31 chronic fatigue syndrome (CFS) subjects and 31 matched control subjects. All variables were assessed weekly over a 4-week period and reliability was determined using an intraclass correlation coefficient (ICC). Results ranged from moderately to highly reliable for all variables assessed, except for mental and physical fatigue, which were of questionable reliability in both groups (ICC = 0.61 and 0.65, respectively, for the CFS group; 0.62 and 0.52 for the control group). A Pearson product-moment correlation analysis that compared exercise performance with all psychological variables assessed, demonstrated a significant relationship between exercise performance and depression (r = .41, P = .02) in week 3 only, suggesting minimal association between objective performance and psychological responses. These correlation results support a central, as opposed to a peripheral, basis to the sensation of fatigue in CFS.
authors.affiliation: School of Human Movement and Exercise Science, The University of Western Australia, Crawely, Western Australia, Australia. kwallman@cyllene.uwa.edu.au
authors.forename: Karen E
authors.initials: KE
authors.lastname: Wallman
authors.forename: Alan R
authors.initials: AR
authors.lastname: Morton
authors.forename: Carmel
authors.initials: C
authors.lastname: Goodman
authors.forename: Robert
authors.initials: R
authors.lastname: Grove
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D015673:Fatigue Syndrome, Chronic / Q000503:physiopathology* / Q000523:psychology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011569:Psychiatric Status Rating Scales; D011581:Psychological Tests; D015203:Reproducibility of Results