title: Identifying physical activity patterns in chronic fatigue syndrome using actigraphic assessment.
abstract: OBJECTIVE
  Changes in physical activity are thought to play an important role in maintaining symptoms in chronic fatigue syndrome (CFS). The aim of this study was to describe intraindividual physical activity patterns in more detail and to identify pervasively passive patients.
  
  
  METHODS
  With help of a movement-sensing device, physical activity levels were registered continuously over a 12-day period in 277 CFS patients. Within this registration period, the 10 largest activity peaks were computed. The intensity and duration of these activity peaks and their subsequent rest periods were described and compared to those of 47 healthy controls. In addition, the patients' 12 daily activity scores were used to identify patients who were characterised by low levels of physical activity throughout the registration period.
  
  
  RESULTS
  The CFS sample had less intense and shorter activity peaks, while the average rest periods that followed these peaks lasted longer. Approximately one-fourth of the CFS sample differed distinctly from the control group and was labelled as pervasively passive.
  
  
  CONCLUSIONS
  The measurements and classification of actual physical activity levels were found to reduce heterogeneity in the CFS population and therefore could provide the opportunity to optimise behavioural intervention protocols for CFS.
authors.affiliation: The Netherlands Fatigue Research Group Nijmegen, Department of Medical Psychology and Internal Medicine, University Hospital Nijmegen, Post Box 9101, 6500 HB, Nijmegen, The Netherlands. s.vanderwerf@cksmps.azn.nl
authors.forename: S P
authors.initials: SP
authors.lastname: van der Werf
authors.forename: J B
authors.initials: JB
authors.lastname: Prins
authors.forename: J H
authors.initials: JH
authors.lastname: Vercoulen
authors.forename: J W
authors.initials: JW
authors.lastname: van der Meer
authors.forename: G
authors.initials: G
authors.lastname: Bleijenberg
mesh_terms: D000293:Adolescent; D000328:Adult; D004185:Disability Evaluation; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D017286:Polysomnography / Q000379:methods*