Influence of Hypoxia on the Power-duration Relationship during High-intensity Exercise

Abstract

We investigated the influence of hypoxia on the asymptote (critical power, CP) and the curvature constant (W′) of the hyperbolic power-duration relationship, as measured by both conventional and all-out testing procedures. 13 females completed 5 constant-power prediction trials and a 3-min all-out test to estimate CP and W′, in both normoxia (N) and moderate hypoxia (H; F_iO₂=0.13). CP was significantly reduced in hypoxia compared to normoxia when estimated by conventional (H:132±17 vs. N:175±25 W; P<0.001) and all-out methods (H:134±23 vs. N:172±30 W; P<0.01). The W′ was not significantly different in hypoxia compared to normoxia when established by conventional (H:12.3±2.7 vs. N:13.2±2.2 kJ) and all-out methods (H:12.0±2.6 vs. N:12.5±1.4 kJ). Estimates of CP and W′ obtained with conventional and all-out methods were not significantly different either in normoxia or hypoxia. There was a significant relationship between the % change in CP relative to V̇;o_2peak and the % change in W′ in normoxia compared to hypoxia (r=0.83, P<0.001; conventional test). Changes in the W′ in hypoxia are related to changes in the CP relative to V̇o_2peak, suggesting that the W′ may not be defined simply as an ‘anaerobic’ energy store.

Key words

power-duration relationship - critical power - curvature constant - hypoxia - exercise tolerance

• References

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