Prediction of Critical Power and W' in Hypoxia: Application to Work-Balance Modelling

• Published in: Frontiers in physiology Vol. 8; p. 180
• Main Authors: Townsend, Nathan E, Nichols, David S, Skiba, Philip F, Racinais, Sebastien, Périard, Julien D
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 23-03-2017
• Subjects: Physiology; altitude; hypoxia; fatigue; cycling; high-intensity intermittent exercise
• ISSN: 1664-042X; 1664-042X
• DOI: 10.3389/fphys.2017.00180

Develop a prediction equation for critical power (CP) and work above CP (W') in hypoxia for use in the work-balance ([Formula: see text]) model.
Nine trained male cyclists completed cycling time trials (TT; 12, 7, and 3 min) to determine CP and W' at five altitudes (250, 1,250, 2,250, 3,250, and 4,250 m). Least squares regression was used to predict CP and W' at altitude. A high-intensity intermittent test (HIIT) was performed at 250 and 2,250 m. Actual and predicted CP and W' were used to compute W' during HIIT using differential ([Formula: see text]) and integral ([Formula: see text]) forms of the [Formula: see text] model.
CP decreased at altitude (
< 0.001) as described by 3rd order polynomial function (
= 0.99). W' decreased at 4,250 m only (
< 0.001). A double-linear function characterized the effect of altitude on W' (
= 0.99). There was no significant effect of parameter input (actual vs. predicted CP and W') on modelled [Formula: see text] at 2,250 m (
= 0.24). [Formula: see text] returned higher values than [Formula: see text] throughout HIIT (
< 0.001). During HIIT, [Formula: see text] was not different to 0 kJ at completion, at 250 m (0.7 ± 2.0 kJ;
= 0.33) and 2,250 m (-1.3 ± 3.5 kJ;
= 0.30). However, [Formula: see text] was lower than 0 kJ at 250 m (-0.9 ± 1.3 kJ;
= 0.058) and 2,250 m (-2.8 ± 2.8 kJ;
= 0.02).
The altitude prediction equations for CP and W' developed in this study are suitable for use with the [Formula: see text] model in acute hypoxia. This enables the application of [Formula: see text] modelling to training prescription and competition analysis at altitude.