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

Abstract

Objective

To describe different end criteria for reaching maximal oxygen uptake (VO _2max) 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 VO _2max 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 VO _2max was studied;VO ₂ leveling off, maximal heart rate (HR _max), 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 HR _max, 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 VO ₂; 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 VO ₂ plateau. When using RER ≥1.15 or blood lactate concentration ≥8.0 mmol•L ^–1, VO _2max was 4% ( P = 0.012) and 10% greater ( P<0.001), respectively. A blood lactate concentration ≥8.0 mmol•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 VO _2max outcome. Suggestions for new recommendations are given.