Stroke volume responses may be related to the gap between peak and maximal O 2 consumption

Abstract

BACKGROUND:

Although several studies have focused on maximal O₂ uptake ( $\dot{V}$ O_2max) measured by a verification phase following the determination of peak O₂ uptake ( $\dot{V}$ O_2peak) by a graded exercise test, an explanation for the underlying mechanisms of the difference between $\dot{V}$ O_2peak and confirmed $\dot{V}$ O_2max is scant.

OBJECTIVE:

To explore the hypothesis that when the difference between $\dot{V}$ O_2peak and $\dot{V}$ O_2max(Δ $\dot{V}$ O₂) increases, the gap between peak stroke volume (SV_peak) and SV level corresponding to $\dot{V}$ O_2peak velocities (Δ SV) grows.

METHODS:

Nine moderately to well-trained male athletes( $\dot{V}$ O_2max: 60.2 ± 7 mL ⋅ min^-1 ⋅ kg^-1) volunteered to take part in the study. Following familiarization session, volunteers were asked to perform submaximal and maximal graded exercise tests. Then, constant-loading SV_peak tests (using wattages in a range from 40-100% of $\dot{V}$ O_2peak) and verification phase (using wattages corresponding with 100-110% of $\dot{V}$ O_2peak) were conducted in a climatic chamber.

RESULTS:

The Δ $\dot{V}$ O₂ was well correlated withΔ SV (Pearson r= 0.89; p≤ 0.001). The mean SV_peak of participants corresponded to 60.3 ± 18% of $\dot{V}$ O_2peak. $\dot{V}$ O_2max was significantly greater (11.2%) than $\dot{V}$ O_2peak (60.2 ± 7 vs. 54.2 ± 8.1 mL ⋅ min^-1 ⋅ kg^-1) (p ≤ 0.01).

CONCLUSIONS:

$\dot{V}$ O_2peak and $\dot{V}$ O_2max differences may be related to the gap between SV_peak and SV at $\dot{V}$ O_2peak.

Keywords

Cardiac output nitrous-oxide peak oxygen uptake rebreathing verification phase

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