Modeling intermittent cycling performance in hypoxia using the critical power concept
Purpose: Recently, a novel model derived from the critical power (CP) concept was developed to determine W’
balance (W’BAL) during variable intensity exercise. The purpose of this study was to investigate the effect of hypoxia on the efficacy of the W’BAL model during high-intensity intermittent exercise.
Methods: Eleven trained, male cyclists (mean±SD; age 27±6.6 years, VO2peak 4.79±0.56) completed a maximal incremental ramp test and a 3 min “all out” test to determine end power (EP) and work performed above EP (W’EP). On another day an intermittent test to task failure was performed. All procedures were performed in normoxia (NORM) and hypoxia (HYPO; FiO2 ≈ 0.155). The experimental condition was single-blinded, randomized and counter-balanced, and the W’BAL model was used to calculate the minimum W’ (W’BALmin) achieved during the intermittent test. W’BALmin in HYPO was also calculated using model parameters derived in NORM (N+H).
Results: In HYPO there was a significant decline in VO2peak (4.79±0.56 vs 3.93±0.47 L.min-1; P<0.001) and EP (353±46 vs 319±49W; P<0.001), whereas no change occurred for W’EP (12.6±4.1 vs 13.3±5.3kJ; P=0.34; NORM vs HYPO). The change in VO2peak was significantly correlated with the change in EP (r = 0.72; P<0.05). There was no difference between NORM and HYPO for W’BALmin (1.7±0.9kJ vs 1.3±0.8kJ). The N+H analysis revealed a gross overestimation of W’BALmin (8.3±3.2kJ) and compared with HYPO (P<0.001). Figure 1 shows an example of modeled W’BAL for a typical subject.
Conclusion: The W’BAL model behaves similarly in hypoxic conditions equivalent to ≈2450m as previously reported for normoxia, but only when the model parameters (CP and W’) are determined under the same environmental conditions as the performance task is completed. The practical application of the W’BAL model for altitude training and performance monitoring, thus requires CP and W’ to be measured at altitude.
How to Cite
Copyright (c) 2015 Journal of Science and Cycling
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Authors contributing to Journal of Science and Cycling agree to publish their articles under a Creative Commons CC BY-NC-ND license, allowing third parties to copy and redistribute the material in any medium or format, and to remix, transform, and build upon the material, for any purpose, even commercially, under the condition that appropriate credit is given, that a link to the license is provided, and that you indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
Authors retain copyright of their work, with first publication rights granted to Cycling Research Center.