title: Conventional testing methods produce submaximal values of maximum oxygen consumption.
abstract: BACKGROUND
  This study used a novel protocol to test the hypothesis that a plateau in oxygen consumption (VO(2 max)) during incremental exercise testing to exhaustion represents the maximal capacity of the cardiovascular system to transport oxygen.
  
  
  METHODS
  Twenty-six subjects were randomly divided into two groups matched by their initial VO(2 max). On separate days, the reverse group performed (i) an incremental uphill running test on a treadmill (INC(1)) plus verification test (VER) at a constant workload 1 km h(-1) higher than the last completed stage in INC(1); (ii) a decremental test (DEC) in which speed started as same as the VER but was reduced progressively and (iii) a final incremental test (INC(F)). The control group performed only INC on the same days that the reverse group was tested.
  
  
  RESULTS
  VO(2 max) remained within 0.6 ml kg(-1) min(-1) across the three trials for the control group (p=0.93) but was 4.4% higher during DEC compared with INC(1) (63.9 ± 3.8 vs 61.2 ± 4.8 ml kg(-1) min(-1), respectively, p=0.004) in the reverse group, even though speed at VO(2 max) was lower (14.3 ± 1.1 vs 16.2 ± 0.7 km h(-1) for DEC and INC(1), respectively, p=0.0001). VO(2 max) remained significantly higher during INC(F) (63.6 ± 3.68 ml kg(-1) min(-1), p=0.01), despite an unchanged exercise time between INC(1) and INC(F).
  
  
  CONCLUSIONS
  These findings go against the concept that a plateau in oxygen consumption measured during the classically described INC and VER represents a systemic limitation to oxygen use. The reasons for a higher VO(2) during INC(F) following the DEC test are unclear.
authors.affiliation: Exercise Sciences and Sports Medicine Unit, Human Biology Department, University of Cape Town, Cape town, South Africa. fernando.beltrami@uct.ac.za
authors.forename: Fernando G
authors.initials: FG
authors.lastname: Beltrami
authors.forename: Christian
authors.initials: C
authors.lastname: Froyd
authors.forename: Alexis R
authors.initials: AR
authors.lastname: Mauger
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Metcalfe
authors.forename: Frank
authors.initials: F
authors.lastname: Marino
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Noakes
mesh_terms: D000293:Adolescent; D000328:Adult; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D056152:Respiratory Rate / Q000502:physiology; D012420:Running / Q000502:physiology*; D055815:Young Adult