title: Responses to exercise differ for chronic fatigue syndrome patients with fibromyalgia.
abstract: Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are chronic multisymptom illnesses with substantial clinical and diagnostic overlap. We have previously shown that, when controlling for aerobic fitness and accounting for comorbid FM, CFS patients do not exhibit abnormal cardiorespiratory responses during maximal aerobic exercise compared with healthy controls, despite differences in pain and exertion.
  
  
  OBJECTIVE
  The purpose of the present study was to examine cardiac and perceptual responses to steady-state submaximal exercise in CFS patients and healthy controls.
  
  
  METHODS
  Twenty-one CFS patients (13 CFS with comorbid FM (CFS + FM)) and 14 controls completed 20 min of submaximal cycling exercise. Impedance cardiography was used to determine cardiac responses during exercise. Systolic blood pressure (SBP), RPE, and leg muscle pain were also measured. Data were analyzed using a doubly multivariate, repeated-measures MANOVA to model the exercise response.
  
  
  RESULTS
  There was a significant multivariate time-by-group interaction (P < 0.05). The CFS + FM group exhibited an exercise response characterized by higher stroke index, ventilatory equivalents for oxygen and carbon dioxide and RPE, lower SBP, and similar HR responses compared to controls.
  
  
  CONCLUSIONS
  The present results extend on our previous work with maximal exercise and show that CFS and CFS + FM differ in their responses to steady-state exercise. These results highlight the importance of accounting for comorbid conditions when conducting CFS research, particularly when examining psychophysiological responses to exercise.
authors.affiliation: Department of Kinesiology, University of Wisconsin - Madison, Madison, WI 53706, USA. dcook@education.wisc.edu
authors.forename: Dane B
authors.initials: DB
authors.lastname: Cook
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Stegner
authors.forename: Paul R
authors.initials: PR
authors.lastname: Nagelkirk
authors.forename: Jacob D
authors.initials: JD
authors.lastname: Meyer
authors.forename: Fumiharu
authors.initials: F
authors.lastname: Togo
authors.forename: Benjamin H
authors.initials: BH
authors.lastname: Natelson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002307:Cardiography, Impedance; D016022:Case-Control Studies; D004562:Electrocardiography; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D015673:Fatigue Syndrome, Chronic / Q000503:physiopathology / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D008297:Male; D016896:Treatment Outcome