The present study was designed to investigate whether absolute work rate (WR) affects Phase I pulmonary oxygen uptake (V̇o2p) duration during moderate-intensity (Mod) exercise and to compare two methods for estimating Phase I V̇o2p duration (PI-Dur). Fourteen males (24 ± 5 yr) each completed 4–8 repetitions of Mod transitions from 20 W to 50, 70, 90, 110, and 130 W. PI-Dur was identified by 1) a marked decrease in both respiratory exchange ratio and end-tidal partial pressure of O2 following exercise onset [i.e., visual inspection of three independent reviewers, and the average (Avg) of the two most similar values]; or 2) the intersection (time delay, TD) of the first and second components in a biexponential nonlinear regression of the entire V̇o2p response from exercise onset. PI-Dur did not differ among WRs (P > 0.05), regardless of the estimation method used. No differences were detected between Avg and TD (time in s) at any of the five WRs (50 W, 21 ± 6 vs. 23 ± 10 s; 70 W, 23 ± 9 vs. 23 ± 7 s; 90 W, 24 ± 3 vs. 22 ± 5 s; 110 W, 23 ± 6 vs. 22 ± 6 s; 130 W, 21 ± 6 vs. 21 ± 7 s; P > 0.05 for Avg and TD, respectively). Broad limits of agreement within Bland-Altman plots revealed relatively weak agreement among reviewers for individual estimation of PI-Dur. A nonsignificant correlation coefficient (r = 0.13) and broad limits of agreement suggest disparity between individual Avg and TD estimates of PI-Dur. The present data do not support a role for Mod WR in determining PI-Dur per se. Furthermore, this study illustrated a poor agreement of PI-Dur estimates derived from two different, but accepted methods.

Duration of 'Phase I' VO2p: a comparison of methods used in its estimation and the effects of varying moderate-intensity work rate.

ZERBINI, Livio;POGLIAGHI, Silvia;
2013

Abstract

The present study was designed to investigate whether absolute work rate (WR) affects Phase I pulmonary oxygen uptake (V̇o2p) duration during moderate-intensity (Mod) exercise and to compare two methods for estimating Phase I V̇o2p duration (PI-Dur). Fourteen males (24 ± 5 yr) each completed 4–8 repetitions of Mod transitions from 20 W to 50, 70, 90, 110, and 130 W. PI-Dur was identified by 1) a marked decrease in both respiratory exchange ratio and end-tidal partial pressure of O2 following exercise onset [i.e., visual inspection of three independent reviewers, and the average (Avg) of the two most similar values]; or 2) the intersection (time delay, TD) of the first and second components in a biexponential nonlinear regression of the entire V̇o2p response from exercise onset. PI-Dur did not differ among WRs (P > 0.05), regardless of the estimation method used. No differences were detected between Avg and TD (time in s) at any of the five WRs (50 W, 21 ± 6 vs. 23 ± 10 s; 70 W, 23 ± 9 vs. 23 ± 7 s; 90 W, 24 ± 3 vs. 22 ± 5 s; 110 W, 23 ± 6 vs. 22 ± 6 s; 130 W, 21 ± 6 vs. 21 ± 7 s; P > 0.05 for Avg and TD, respectively). Broad limits of agreement within Bland-Altman plots revealed relatively weak agreement among reviewers for individual estimation of PI-Dur. A nonsignificant correlation coefficient (r = 0.13) and broad limits of agreement suggest disparity between individual Avg and TD estimates of PI-Dur. The present data do not support a role for Mod WR in determining PI-Dur per se. Furthermore, this study illustrated a poor agreement of PI-Dur estimates derived from two different, but accepted methods.
VO2 kinetics; cardiodynamic phase; moderate-intensity exercise
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11562/488551
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