title: Nitric oxide metabolite production during exercise in chronic fatigue syndrome: a case-control study.
abstract: BACKGROUND
  Chronic fatigue syndrome (CFS) is a disabling illness of unknown etiology that is characterized by fatigue associated with a reduced ability to work, lasting for more than 6 months, and accompanied by a specific set of symptoms. The diagnosis remains difficult because of the absence of laboratory tests and is, therefore, made largely on the basis of the symptoms reported by the patient. The aim of this study was to analyze differences in blood nitrate levels in CFS patients and a matched control group after a physical exercise test.
  
  
  METHODS
  Forty-four consecutive female patients with CFS and 25 healthy women performed an exercise test using a cycle ergometer with monitoring of cardiopulmonary response. Blood samples were obtained for biochemical analyses of glucose, lactate, and nitrates at the beginning (under resting conditions) and after the maximal and supramaximal tests.
  
  
  RESULTS
  Plasma nitrates differed between the groups, with higher values in the CFS group (F = 6.93, p = 0.003). Nitrate concentration increased in relation to workload and reached higher values in the CFS group, the maximum difference with respect to the control group being 295% (t = 4.88, p < 0.001).
  
  
  CONCLUSIONS
  The main result of the present study is that nitric oxide (NO) metabolites (nitrates) showed a much higher increase after a maximal physical test in CFS patients than in a group of matched subjects. This combination (exercise plus NO response evaluation) may be useful in the assessment of CFS.
authors.affiliation: Department of Physiological Sciences II, Medical School, University of Barcelona, L'Hospitalet, Barcelona, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Suárez
authors.forename: Elisabet
authors.initials: E
authors.lastname: Guillamó
authors.forename: Teresa
authors.initials: T
authors.lastname: Roig
authors.forename: Alicia
authors.initials: A
authors.lastname: Blázquez
authors.forename: José
authors.initials: J
authors.lastname: Alegre
authors.forename: Jordi
authors.initials: J
authors.lastname: Bermúdez
authors.forename: José Luis
authors.initials: JL
authors.lastname: Ventura
authors.forename: Ana María
authors.initials: AM
authors.lastname: García-Quintana
authors.forename: Agustí
authors.initials: A
authors.lastname: Comella
authors.forename: Ramon
authors.initials: R
authors.lastname: Segura
authors.forename: Casimiro
authors.initials: C
authors.lastname: Javierre
mesh_terms: D000704:Analysis of Variance; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D015673:Fatigue Syndrome, Chronic / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000097:blood
chemical_list: D009569:Nitric Oxide