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Mechanisms which control VO2 near VO2max: an overview
1Department of Physiology and Biophysics, University of Alabama at Birmingham 35294-0005.
Medicine and Science in Sports and Exercise
|January 1, 1995
Summary
Oxygen transport to muscle involves a variable impediment, termed O2 conductance. Muscle VO2 is limited by O2 supply and demand, with O2 extraction showing a narrow range despite varying conductance.
Area of Science:
- Exercise Physiology
- Cardiovascular Physiology
- Muscle Metabolism
Background:
- Oxygen uptake (VO2) near maximal capacity (VO2max) is crucial for muscle function.
- A variable impediment exists for O2 movement from red blood cells to mitochondria.
Purpose of the Study:
- To discuss mechanisms controlling VO2 near VO2max.
- To propose 'O2 conductance' as a term for VO2/PvO2 ratio.
- To explore factors limiting VO2 in contracting muscle.
Main Methods:
- Symposium discussion and synthesis of existing data.
- Analysis of VO2 in relation to O2 delivery and extraction.
- Consideration of factors affecting O2 transport and utilization.
Main Results:
- General agreement on a variable impediment to O2 transport.
- O2 conductance is alterable by changing O2 delivery or muscle contraction conditions.
- O2 extraction shows a narrow range when plotted against O2 delivery, except under altered hemoglobin function or extreme flow rates.
Conclusions:
- VO2 limits in contracting muscle are influenced by both O2 supply and O2 demand.
- Further research is needed on factors contributing to O2 conductance and control of muscle blood flow and contractile force.