title: Maximal oxygen uptake and lactate metabolism are normal in chronic fatigue syndrome.
abstract: OBJECTIVE
  Previous studies in chronic fatigue syndrome (CFS) have reported reductions in maximal oxygen uptake (VO(2max)), yet often the testing procedures have not followed accepted guidelines, and gender data have been pooled. The present study was undertaken to reevaluate exercise capacity in CFS patients by using "gold standard" maximal exercise testing methodology and stratifying results on a gender basis.
  
  
  METHODS
  Sixteen male and 17 female CFS patients and their gender-, age-, and mass-matched sedentary controls performed incremental exercise to volitional exhaustion on a stationary cycle ergometer while selected cardiorespiratory and metabolic variables were measured.
  
  
  RESULTS
  VO(2max) in male CFS patients was not different from control values (CFS: 40.5 +/- 6.7; controls: 43.3 +/- 8.6; mL x kg(-1) x min(-1)) and was 96.3 +/- 17.9% of the age-predicted value, indicating no functional aerobic impairment (3.7 +/- 17.9%). In female CFS patients, VO(2max) was lower than control values (CFS: 30.0 +/- 4.7; controls: 34.2 +/- 5.6; mL x kg(-1) x min(-1), P = 0.002), but controls were higher than the age-predicted value (112.6 +/- 15.4%, P = 0.008) whereas the CFS patients were 101.2 +/- 20.4%, indicating no functional aerobic impairment (-1.2 +/- 20.4%). Maximal heart rate (HR(max)) in male CFS patients was lower than their matched controls (CFS: 184 +/- 10; controls: 192 +/- 12; beats x min(-1); P = 0.016) but was 99.1 +/- 5.5% of their age-predicted value. In female CFS patients, HR(max) was not different from controls (CFS: 183 +/- 11; controls: 186 +/- 10; beats x min(-1)) and was 98.9 +/- 5.1% of the age-predicted value. The VO(2) at the lactate threshold (LT) in each gender group, whether expressed in mL x kg(-1) x min(-1) or as a percentage of VO(2max), was not different between CFS patients and controls.
  
  
  CONCLUSIONS
  In contrast to most previous reports, the present study found that VO(2max), HR(max), and the LT in CFS patients of both genders were not different from the values expected in healthy sedentary individuals of a similar age.
authors.affiliation: Exercise Physiology Research Unit, Department of Physiology, University of Adelaide, South Australia 5005, Australia.
authors.forename: Charli
authors.initials: C
authors.lastname: Sargent
authors.forename: Garry C
authors.initials: GC
authors.lastname: Scroop
authors.forename: Peter M
authors.initials: PM
authors.lastname: Nemeth
authors.forename: Richard B
authors.initials: RB
authors.lastname: Burnet
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Buckley
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D015673:Fatigue Syndrome, Chronic / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D012737:Sex Factors
chemical_list: D019344:Lactic Acid