title: V˙O2max may not be reached during exercise to exhaustion above critical power.
abstract: OBJECTIVE
  This study was designed to determine whether V˙O(2) reaches a maximum, equivalent to that attained in an incremental exercise test to exhaustion, during "submaximal" fatigue-inducing constant-power exercise bouts above critical power (CP).
  
  
  METHODS
  Nine males (age = 24.6 ± 3.6 yr, height = 182.8 ± 6.9 cm, weight = 77.8 ± 12.1 kg) and four females (age = 29.0 ± 7.3 yr, height = 170.8 ± 3.2 cm, weight = 61.8 ± 8.2 kg) underwent an incremental V˙O(2max) test (IET) on a cycle ergometer, followed by four or five randomly assigned constant-power exercise bouts to exhaustion, on separate days. The CP for each subject was estimated using linear and nonlinear regression.
  
  
  RESULTS
  IET V˙O(2max) averaged 3.55 ± 0.92 L·min (RER = 1.21 ± 0.05, HR = 186 ± 10 bpm, 96.1% ± 6.3% of age-predicted maximum). Mean peak V˙O(2) (range = 3.32 ± 0.88 to 3.54 ± 0.91 L·min) during the three highest constant-power bouts (two of which were 53 to 82 W less than peak power output attained during IET) was not significantly different from IET V˙O(2max). Eleven of 13 subjects exceeded their IET V˙O(2max) during at least one of the constant-power exercise bouts. However, peak V˙O(2) (3.11 ± 0.79 L·min) during the lowest constant-power exercise bout, which ranged from 10 to 36 W above CP estimated with a two-parameter nonlinear model, was significantly lower than IET V˙O(2max) (88.2% ± 9.4% of IET V˙O(2max)).
  
  
  CONCLUSIONS
  At power outputs above CP, V˙O(2) does not necessarily increase to maximum during constant-power exercise to exhaustion. In addition, the highest V˙O(2) values measured during a traditional V˙O(2) "max" test (i.e., IET) may not reflect the highest attainable V˙O(2) despite V˙O(2max) criteria being met.
authors.affiliation: School of Nutrition and Health Promotion, Arizona State University, Phoenix, AZ, USA.
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Sawyer
authors.forename: R Hugh
authors.initials: RH
authors.lastname: Morton
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Womack
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Gaesser
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005221:Fatigue / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D055815:Young Adult