V̇O 2max may not be reached during exercise to exhaustion above critical power

Brandon J. Sawyer, R. Hugh Morton, Christopher J. Womack, Glenn Gaesser

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Purpose: This study was designed to determine whether V̇O 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 V̇O 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 V̇O 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 V̇O 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 V̇O 2max. Eleven of 13 subjects exceeded their IET V̇O 2max during at least one of the constant-power exercise bouts. However, peak V̇O 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 V̇O 2max (88.2% ± 9.4% of IET V̇O 2max). Conclusions: At power outputs above CP, V̇O 2 does not necessarily increase to maximum during constant-power exercise to exhaustion. In addition, the highest V̇O 2 values measured during a traditional V̇O 2 "max" test (i.e., IET) may not reflect the highest attainable V̇O 2 despite V̇O 2max criteria being met.

Original languageEnglish (US)
Pages (from-to)1533-1538
Number of pages6
JournalMedicine and science in sports and exercise
Issue number8
StatePublished - Aug 2012


  • Fatigue
  • aerobic capacity
  • endurance
  • exercise tolerance
  • muscular work
  • severe-intensity exercise

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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