Commentary on the effects of hypoxia on energy substrate use during exercise

Abstract

A recently published meta-analysis in this journal analyzed findings from studies comparing substrate use during exercise at the same relative intensity (i.e., % V̇O₂max) in normoxic and hypoxic conditions. The primary conclusion was that hypoxia had no consistent effects on the contribution of carbohydrate oxidation to total energy expenditure. However, findings from studies comparing exercise at the same absolute intensity in normoxic as hypoxic conditions were not considered in the meta-analysis. Assessment of substrate oxidation using matched absolute intensity leads to different conclusions regarding hypoxic effects on fuel use during exercise, and that experimental model, (i.e., comparing responses to exercise at matched absolute intensity) has more practical application for developing nutritional recommendations for high-altitude sojourners. This commentary will discuss those differences.

Keywords:

• High altitude
• Carbohydrate oxidation
• Nutrition
• Mountaineering

Acknowledgements

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Conflict of interest

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Army or the Department of Defense. Any citations of commercial organizations and trade names in this report do not constitute an official Department of the Army endorsement of approval of the products or services of these organizations.

Authors’ contributions

AJY drafted the manuscript, all authors reviewed and edited the manuscript and approved the final version.

Funding

Funding support for this work was provided by the US Army Medical Research and Materiel Command.

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Competing interests

The authors declare that they have no competing interests.

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Notes

1 For this commentary, we only consider the effects of exposure to ≤ 24 h of hypoxia or high altitude.