The Minimal Difference as an Individual Threshold to Examine the Utility of a Verification Bout in Determining V̇O 2max

Abstract

Purpose: A square-wave verification bout to confirm maximal oxygen uptake (V̇O 2max ) 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 V̇O 2 from the GXT (V̇O 2GXT ) and verification bout (V̇O 2verification ) to examine the efficacy of a verification bout in the determination of O 2max 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 V̇O 2GXT and V̇O 2verification . 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 (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 = 0.300) and no main effect for test ( P = 0.690), but there was a main effect for method ( P = 0.003). The V̇O 2GXT (46.0 mL⋅kg -1 ⋅min -1 ) was significantly greater than V̇O 2verification (43.9 mL⋅kg -1 ⋅min -1 ), collapsed across test. The V̇O 2GXT (ICC = 0.970, SEM = 1.63 mL⋅kg -1 ⋅min -1 , MD = 4.51 mL⋅kg -1 ⋅min -1 , COV = 3.54%) and the V̇O 2verification (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 V̇O 2GXT or V̇O 2verification . No subject had a V̇O 2verification that exceeded V̇O 2GXT by more than the MD, but two subjects had a V̇O 2GXT , which exceeded V̇O 2verification by more than the MD.

Conclusions: The excellent reliability of V̇O 2GXT in addition to the examination of the individual differences between V̇O 2GXT and V̇O 2verification using the MD indicated that a standalone GXT was sufficient to determine V̇O 2max .