Maximal oxygen uptake (VO2max), an assessment of cardiorespiratory fitness, is regularly used as the primary outcome in exercise interventions. Many criteria have been suggested for validating such tests—most commonly, a plateau in oxygen consumption. The current study investigated the proportion of inactive individuals who reached a plateau in oxygen uptake and who achieved a valid test as assessed by secondary criteria (RERmax ≥ 1.1; RPEmax ≥ 18; age predicted HRmax ±10bpm), and the correlates of a successful plateau or achievement of secondary criteria during a VO2max session.
Participants (n = 240) were inactive individuals who completed VO2max assessments using an incremental treadmill test. We explored physical, behavioral, and motivational factors as predictors of meeting criteria for meeting a valid test.
Approximately 59% of the sample achieved plateau using absolute (increase of VO2 of 150ml O2 or less) and 37% achieved plateau using relative (increase of VO2 of 1.5ml/kg O2 or less) criteria. Being male, having a higher BMI, a greater waist-to-hip ratio, and increased self-efficacy were associated with lower odds of achieving an absolute plateau, whereas none of these factors predicted odds of achieving relative plateau.
Findings raise questions about the validity of commonly used criteria with less active populations.
Magnan was with the Dept of Psychology, University of New Mexico, Albuquerque, NM, and is now with the Dept of Psychology, Washington State University–Vancouver, Vancouver, WA. Kwan is with the Colorado Health Outcomes Program, University of Colorado–Denver. Ciccolo is with Warren Alpert Medical School, Brown University, Providence, RI. Gurney is with the Dept of Physical Therapy, University of New Mexico, Albuquerque, NM. Mermier is with the Internal Medicine Department, University of New Mexico, Albuquerque, NM. Bryan is with the Dept of Psychology and Neuroscience, University of Colorado at Boulder.