Methodological considerations for the determination of VO_2max in healthy men

Purpose: A square-wave verification bout to confirm maximal oxygen uptake (V ˙ O_2max) from a graded exercise test (GXT) has been recommended. This study ascertained if a verification bout is necessary to determine V ˙ 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 V ˙ O_2GXT and V ˙ O_{2verification} (highest V ˙ 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 V ˙ O_2GXT (50.9±3.0 mL·kg⁻¹·min⁻¹) was greater than V ˙ O_{2verification} (46.9 ± mL·kg⁻¹·min⁻¹). The V ˙ 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 V ˙ 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 V ˙ O_2GXT test–retest or for V ˙ O_{2verification} test–retest, but 50% of subjects had a V ˙ O_2GXT that was greater than the V ˙ O_{2verification} (> MD). Conclusion: While V ˙ O_2GXT and V ˙ O_{2verification} demonstrated excellent reliability, V ˙ O_2GXT from a stand-alone GXT provided higher estimates of V ˙ O₂ and, therefore, should be considered V ˙ O_2max. The lack of test–retest differences in V ˙ O_2GXT above the MD indicated that subjects achieved their highest V ˙ O₂ (V ˙ O_2max) from a standalone GXT. Therefore, the verification bout may not be required to confirm V ˙ O_2max in this population.