The Minimal Difference as an Individual Threshold to Examine the Utility of a Verification Bout in Determining V̇O2max

Abstract

ABSTRACT Purpose A square-wave verification bout to confirm maximal oxygen uptake (V̇O2max) from a graded exercise test (GXT) has been recommended based on mean responses. This study used the test–retest reliability, mean, and individual differences between the highest V̇O2 from the GXT (V̇O2GXT) and verification bout (V̇O2verification) to examine the efficacy of a verification bout in the determination of O2max in healthy, recreationally trained, well-motivated men. Methods Ten men (24 ± 4 yr) completed a GXT on a cycle ergometer followed by a submaximal verification bout to determine V̇O2GXT and V̇O2verification. After completion of the initial GXT, subjects rested for 5 min then performed the verification bout at 90% of the peak power output from the initial GXT. Analyses included a two-way repeated-measures ANOVA, intraclass correlation coefficients (ICC2,1), 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 = 0.300) and no main effect for test (P = 0.690), but there was a main effect for method (P = 0.003). The V̇O2GXT (46.0 mL⋅kg−1⋅min−1) was significantly greater than V̇O2verification (43.9 mL⋅kg−1⋅min−1), collapsed across test. The V̇O2GXT (ICC = 0.970, SEM = 1.63 mL⋅kg−1⋅min−1, MD = 4.51 mL⋅kg−1⋅min−1, COV = 3.54%) and the V̇O2verification (ICC = 0.953, SEM = 1.87 mL⋅kg−1⋅min−1, MD = 5.17 mL⋅kg−1⋅min−1, COV = 4.25%) demonstrated “excellent” reliability. No subject exceeded the MD test–retest for V̇O2GXT or V̇O2verification. No subject had a V̇O2verification that exceeded V̇O2GXT by more than the MD, but two subjects had a V̇O2GXT, which exceeded V̇O2verification by more than the MD. Conclusions The excellent reliability of V̇O2GXT in addition to the examination of the individual differences between V̇O2GXT and V̇O2verification using the MD indicated that a standalone GXT was sufficient to determine V̇O2max.