Increases in $\dot{V}$O_2max with “live high–train low” altitude training: role of ventilatory acclimatization

Abstract

The purpose of this study was to estimate the percentage of the increase in whole body maximal oxygen consumption ($\dot{V}$O_2max) that is accounted for by increased respiratory muscle oxygen uptake after altitude training. Six elite male distance runners ($\dot{V}$O_2max = 70.6 ± 4.5 ml kg⁻¹ min⁻¹) and one elite female distance runner ($\dot{V}$O_2max = 64.7 ml kg⁻¹ min⁻¹) completed a 28-day “live high–train low” training intervention (living elevation, 2,150 m). Before and after altitude training, subjects ran at three submaximal speeds, and during a separate session, performed a graded exercise test to exhaustion. A regression equation derived from published data was used to estimate respiratory muscle $\dot{V}$O₂ ($\dot{V}$O_2RM) using our ventilation ($\dot{V}$ _E) values. $\dot{V}$O_2RM was also estimated retrospectively from a larger group of distance runners (n = 22). $\dot{V}$O_2max significantly (p < 0.05) increased from pre- to post-altitude (196 ± 59 ml min⁻¹), while $\dot{V}$ _E at $\dot{V}$O_2max also significantly (p < 0.05) increased (13.3 ± 5.3 l min⁻¹). The estimated $\dot{V}$O_2RM contributed 37 % of Δ$\dot{V}$O_2max. The retrospective group also saw a significant increase in $\dot{V}$O_2max from pre- to post-altitude (201 ± 36 ml min⁻¹), along with a 10.8 ± 2.1 l min⁻¹ increase in $\dot{V}$ _E, thus requiring an estimated 27 % of Δ$\dot{V}$O_2max. Our data suggest that a substantial portion of the improvement in $\dot{V}$O_2max with chronic altitude training goes to fuel the respiratory muscles as opposed to the musculature which directly contributes to locomotion. Consequently, the time-course of decay in ventilatory acclimatization following return to sea-level may have an impact on competitive performance.