Verification-phase tests show low reliability and add little value in determining <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mrow> <mn>2</mn> </mrow> </msub> <mo>⁢</mo> <mi mathvariant="normal">max</mi> </mrow> </math> in young trained adults.

Abstract

This study compared the robustness of a <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mn>2</mn> </msub> </mrow> </math>-plateau definition and a verification-phase protocol to day-to-day and diurnal variations in determining the true <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mrow> <mn>2</mn> </mrow> </msub> <mo>⁢</mo> <mi mathvariant="normal">max</mi> </mrow> </math>. Further, the additional value of a verification-phase was investigated. Eighteen adults performed six cardiorespiratory fitness tests at six different times of the day (diurnal variation) as well as a seventh test at the same time the sixth test took place (day-to-day variation). A verification-phase was performed immediately after each test, with a stepwise increase in intensity to 50%, 70%, and 105% of the peak power output. Participants mean <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mrow> <mn>2</mn> </mrow> </msub> <mo>⁢</mo> <mi mathvariant="normal">p</mi> <mo>⁢</mo> <mi mathvariant="normal">e</mi> <mo>⁢</mo> <mi mathvariant="normal">a</mi> <mo>⁢</mo> <mi mathvariant="normal">k</mi> </mrow> </math> was 56 ± 8 mL/kg/min. Gwet's AC1 values (95% confidence intervals) for the day-to-day and diurnal variations were 0.64 (0.22, 1.00) and 0.71 (0.42, 0.99) for <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mn>2</mn> </msub> </mrow> </math>-plateau and for the verification-phase 0.69 (0.31, 1.00) and 0.07 (-0.38, 0.52), respectively. In 66% of the tests, performing the verification-phase added no value, while, in 32% and 2%, it added uncertain value and certain value, respectively, in the determination of <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mrow> <mn>2</mn> </mrow> </msub> <mo>⁢</mo> <mi mathvariant="normal">max</mi> </mrow> </math>. Compared to <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mover accent="true"> <mi mathvariant="normal">V</mi> <mo>˙</mo> </mover> <mo>⁢</mo> <msub> <mi mathvariant="normal">O</mi> <mn>2</mn> </msub> </mrow> </math>-plateau the verification-phase shows lower reliability, increases costs and only adds certain value in 2% of cases.