Human aerobic performance: too much ado about limits to V(O(2))

Area of Science:

• Exercise Physiology
• Respiratory Physiology
• Sports Science

Background:

• Human endurance performance is commonly assessed by maximal oxygen uptake during exercise (V(O2max)).
• Strategies to enhance V(O2max) are frequently pursued to improve athletic endurance.
• The respiratory system's role in oxygen delivery and its potential limitations are key areas of investigation.

Purpose of the Study:

• To challenge the notion that a single factor limits oxygen uptake (V(O2max)).
• To investigate the efficiency of the respiratory system in meeting oxygen demands during exercise.
• To evaluate the impact of interventions aimed at increasing oxygen availability on endurance performance.

Main Methods:

• Comparative analysis of V(O2max) across different mammalian species.
• Examination of the effects of isolated respiratory system component limitations on V(O2max).
• Assessment of interventions like blood doping, hyperoxia, and oxygen supplementation in relevant populations.

Main Results:

• V(O2max) exhibits a 5000-fold variation among mammals, indicating diverse physiological adaptations.
• Limitations in single respiratory system components impact V(O2max) by 10% or less.
• Interventions significantly increasing oxygen availability (blood doping, hyperoxia, O2 supplementation) yield only minimal increases in V(O2max).

Conclusions:

• The respiratory system is highly adapted for oxygen delivery, and no single component is rate-limiting for V(O2max).
• Enhancing oxygen delivery through isolated interventions has limited efficacy in boosting maximal oxygen uptake.
• Human aerobic performance is multifactorial, with oxygen uptake being only one important determinant.