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Metabolic and work efficiencies during exercise in Andean natives
P W Hochachka1, C Stanley, G O Matheson
1Department of Zoology, University of British Columbia, Vancouver, Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1991
Summary
Andean Quechua natives exhibit a unique metabolic adaptation, the lactate paradox, allowing efficient exercise in high altitudes. This genetic trait enhances aerobic metabolism and energy efficiency compared to lowlanders.
Area of Science:
- Physiology
- Human Adaptation
- Altitude Research
Background:
- Hypobaric hypoxia at high altitudes poses physiological challenges to exercise.
- Quechua natives from the Andes demonstrate unique adaptations to these conditions.
Purpose of the Study:
- To investigate the physiological mechanisms behind the reduced perturbation of oxygen and carbon dioxide fluxes during exercise in Quechua highlanders compared to lowlanders.
- To explore the 'lactate paradox' in Quechua natives and its implications for metabolic organization.
Main Methods:
- Comparative analysis of maximal O2 and CO2 fluxes during exercise.
- Measurement of lactate accumulation at different altitudes and oxygen conditions.
- Assessment of respiratory quotient and energetic efficiency during varying work rates.
Main Results:
- Quechua highlanders accumulated significantly less lactate than lowlanders under hypoxic conditions, a phenomenon termed the lactate paradox.
- The lactate paradox in Quechuas was found to be a stable metabolic characteristic, not an acclimation.
- Quechua natives demonstrated preferential carbohydrate utilization and approximately 1.5 times higher energetic efficiency at submaximal work rates.
Conclusions:
- The lactate paradox in Quechua natives represents a developmentally or genetically fixed metabolic organization, advantageous for aerobic metabolism in hypoxia.
- This metabolic efficiency is linked to preferential carbohydrate use and downregulated ATP expenditure not convertible to mechanical work.
- These adaptations highlight a unique evolutionary strategy for survival and performance at high altitudes.