The Minimal Difference as an Individual Threshold to Examine the Utility of a Verification Bout in Determining VO2max

Purpose A square-wave verification bout to confirm maximal oxygen uptake (VO2max) 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 VO2 from the GXT (VO2GXT) and verification bout (VO2verification) to examine the efficacy of a verification bout in the determination of V 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 VO2GXT and VO2verification. 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 VO2GXT (46.0 mL⋅kg-1⋅min-1) was significantly greater than VO2verification (43.9 mL⋅kg-1⋅min-1), collapsed across test. The VO2GXT (ICC = 0.970, SEM = 1.63 mL⋅kg-1⋅min-1, MD = 4.51 mL⋅kg-1⋅min-1, COV = 3.54%) and the VO2verification (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 VO2GXT or VO2verification. No subject had a VO2verification that exceeded VO2GXT by more than the MD, but two subjects had a VO2GXT, which exceeded VO2verification by more than the MD. Conclusions The excellent reliability of VO2GXT in addition to the examination of the individual differences between VO2GXT and VO2verification using the MD indicated that a standalone GXT was sufficient to determine VO2max.