Methodological considerations for the determination of VO2max in healthy men

Abstract

Purpose: A square-wave verification bout to confirm maximal oxygen uptake ([Formula: see text]O_2max) from a graded exercise test (GXT) has been recommended. This study ascertained if a verification bout is necessary to determine [Formula: see text]O_2max in moderately trained men.

Methods: Ten men (24 ± 4 years) completed familiarization and two treadmill GXTs, followed by a submaximal verification bout to determine [Formula: see text]O_2GXT and [Formula: see text]O_{2verification} (highest [Formula: see text]O₂ from each testing method). After completing the GXT, subjects rested for 5 min then performed a verification bout at 90% speed and 50% incline at termination of the GXT. The analyses included a 2-way repeated-measures ANOVA, intra-class correlation coefficients (ICC_2,1), standard errors of the measurement (SEM), minimal differences (MD), and coefficients of variation (CoV).

Results: There was no test (test 1 vs test 2) × method (GXT vs verification) interaction (p = 0.584), or main effect for test (p = 0.320), but there was a main effect for method (p = 0.011). The [Formula: see text]O_2GXT (50.9±3.0 mL·kg^-1·min^-1) was greater than [Formula: see text]O_{2verification} (46.9 ± mL·kg^-1·min^-1). The [Formula: see text]O_2GXT (ICC = 0.988, SEM = 1.0 mL·kg^-1 min^-1, MD = 2.9 mL kg^-1 min^-1, CoV = 2.03%) and [Formula: see text]O_{2verification} (ICC = 0.976, SEM = 1.0 mL·kg^-1 min^-1, MD = 2.7 mL·kg^-1·min^-1, CoV = 2.03%) demonstrated "excellent" reliability. No subject exceeded the MD for [Formula: see text]O_2GXT test-retest or for [Formula: see text]O_{2verification} test-retest, but 50% of subjects had a [Formula: see text]O_2GXT that was greater than the [Formula: see text]O_{2verification} (> MD).

Conclusion: While [Formula: see text]O_2GXT and [Formula: see text]O_{2verification} demonstrated excellent reliability, [Formula: see text]O_2GXT from a stand-alone GXT provided higher estimates of [Formula: see text]O₂ and, therefore, should be considered [Formula: see text]O_2max. The lack of test-retest differences in [Formula: see text]O_2GXT above the MD indicated that subjects achieved their highest [Formula: see text]O₂ ([Formula: see text]O_2max) from a standalone GXT. Therefore, the verification bout may not be required to confirm [Formula: see text]O_2max in this population.

Keywords: Cardiorespiratory fitness; Graded exercise test; Reliability; Running.