End Criteria for Reaching Maximal Oxygen Uptake Must Be Strict and Adjusted to Sex and Age: A Cross-Sectional Study

Objective: To describe different end criteria for reaching maximal oxygen uptake (VO2max) during a continuous graded exercise test on the treadmill, and to explore the manner by which different end criteria have an impact on the magnitude of the VO2max result. Methods: A sample of 861 individuals (390 women) aged 20-85 years performed an exercise test on a treadmill until exhaustion. Gas exchange, heart rate, blood lactate concentration and Borg Scale(6-20) rating were measured, and the impact of different end criteria on VO2max was studied;VO2 leveling off, maximal heart rate (HRmax), different levels of respiratory exchange ratio (RER), and postexercise blood lactate concentration. Results: Eight hundred and four healthy participants (93%) fulfilled the exercise test until voluntary exhaustion. There were no sex-related differences in HRmax, RER, or Borg Scale rating, whereas blood lactate concentration was 18% lower in women (P<0.001). Forty-two percent of the participants achieved a plateau in VO2; these individuals had 5% higher ventilation (P= 0.033), 4% higher RER (P<0.001), and 5% higher blood lactate concentration (P= 0.047) compared with participants who did not reach a VO2 plateau. When using RER >= 1.15 or blood lactate concentration >= 8.0 mmol center dot L-1, VO2max was 4% (P= 0.012) and 10% greater (P<0.001), respectively. A blood lactate concentration >= 8.0 mmol center dot L-1 excluded 63% of the participants in the 50-85-year-old cohort. Conclusions: A range of typical end criteria are presented in a random sample of subjects aged 20-85 years. The choice of end criteria will have an impact on the number of the participants as well as the VO2max outcome. Suggestions for new recommendations are given.