Which Cutoffs for Secondary V˙O2max Criteria Are Robust to Diurnal Variations?

Abstract

Purpose The aim was to determine the minimum maximum oxygen uptake (V˙O2max) criteria cut-offs in highly trained athletes (i.e., maximum RER [RERmax], maximum HR [HRmax], maximum RPE [RPEmax], and maximum blood lactate concentration [BLmax]) necessary to determine maximum oxygen uptake (V˙O2max) during cardiopulmonary exercise tests (CPET), by balancing type I and type II errors. A further aim was to investigate if the defined cutoffs would be robust to diurnal and to day-to-day variations. Methods Data from two CPET studies involving young athletes were analyzed. In the first study, 70 male participants performed one CPET until exhaustion to define cutoffs. In the second study, eight males and five females performed one CPET on seven consecutive days at six different times of day (i.e., diurnal variation). The time of the CPET was identical on the sixth and seventh days (i.e., day-to-day variation). To ensure comparability both studies were carried out under the same conditions. Results Participants’ mean V˙O2max was 63.0 ± 5.3 mL·kg−1·min−1. RERmax ≥1.10 was reached by 100%, HRmax ≥95% of age-predicted HRmax by 99%, RPEmax ≥19 by 100%, and BLmax ≥8 mmol·L−1 by 100% of participants, respectively. Regarding the intraday variations, latter cutoffs were not reached in two cases for RERmax and in one case for HRmax and BLmax. Intraclass correlations for the day-to-day variability were r = 0.823 for RERmax, r = 0.828 for HRmax, and r = 0.380 for BLmax, respectively. Conclusions The proposed high cut-off values for secondary criteria provide some assurance that V˙O2max may have been achieved in athletes without increasing type II errors. However, type I errors may still occur indicating that further methods such as V˙O2-plateau or V˙O2-validation may be required.

Low-volume high-intensity interval training improves cardiometabolic health, work ability and well-being in severely obese individuals: a randomized-controlled trial sub-study

“…Although not the subject of the current study, it was a noteworthy finding that only a small proportion of participants, both in the HIIT and CON group, reached RER max ≥ 1.10 (which is typically suggested as a cut-off value indicating that maximal effort has been achieved) at exhaustion during the cycle ergometer tests, despite reaching at least two other maximal effort criteria [ 38 , 39 ]. In accordance with other reports [ 61 , 62 ], this finding may be due to altered substrate utilization during exercise in obese individuals and supports previous studies indicating that the use of secondary criteria like RER max to establish VO 2max may possibly be associated with errors under certain circumstances [ 39 , 63 ].…”

“…Before each test, the device was calibrated according to the manufacturer’s instructions. Criteria to assume that maximal effort was reached were at least two of the following: a leveling-off of oxygen uptake, maximal respiratory exchange ratio (RER max ) ≥ 1.10, ≥ 90% of age predicted HR max (APHR max , using the equation: 220–age) and maximal rate of perceived exertion (RPE max ) ≥ 19 (assessed at exhaustion using the 6–20 Borg scale [ 37 ]) [ 38 , 39 ]. In addition, the ventilatory threshold (VT) was determined according to the V-slope method by plotting carbon dioxide output (VCO 2 ) against oxygen uptake (VO 2 ) in order to assess submaximal exercise capacity [ 40 ].…”

Effect of intensive prior exercise on muscle fiber activation, oxygen uptake kinetics, and oxygen uptake plateau occurrence

“…It serves as an indicator of maximum oxygen uptake ( ), which is one of the most important measurements in exercise physiology and clinical sports medicine (Poole and Jones 2017 ; Hawkins et al 2007 ; Levine 2008). However, even if incremental exercise has been performed with maximal effort, the observed plateau incidence is frequently less than 60% despite high levels of secondary exhaustion criteria (Lucia et al 2006; Knaier et al 2019b ; Wood et al 2010 ). It is widely believed that the occurrence of a -plateau depends on age or aerobic fitness (Howley et al 1995 ; Wagner 2000 ; Shephard, 2009 ).…”

Cardiorespiratory factors related to the increase in oxygen consumption during exercise in individuals with stroke

“…Work rate at peak exercise was defined as the peak wattage on test termination [22]. To identify whether maximal effort was reached during the exercise test, at least 1 of the following criteria had to be met: (1) increased less than 150 mL·min -1 for more than 1 min despite increased work rate, (2) respiratory exchange ratio achieved greater than 1.10, (3) or heart rate achieved 85% of the age-predicted maximal heart rate (210 minus age) [28–30].…”