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Respiratory muscle perfusion and energetics during exercise
J A Dempsey1, C A Harms, D M Ainsworth
1John Rankin Laboratory of Pulmonary Medicine, Department of Preventive Medicine, University of Wisconsin-Madison 53705, USA.
Medicine and Science in Sports and Exercise
|September 1, 1996
Summary
High exercise ventilation demands significant oxygen, potentially limiting endurance performance. Respiratory muscle blood flow may divert from locomotor muscles, causing fatigue.
Area of Science:
- Exercise Physiology
- Respiratory Physiology
Background:
- Breathing requires oxygen and blood flow, especially during strenuous exercise.
- The demands on respiratory muscles can impact overall exercise capacity.
Purpose of the Study:
- To discuss the oxygen cost of breathing and respiratory muscle blood flow during exercise.
- To explore the implications for locomotor muscle function and exercise performance limitations.
Main Methods:
- The study discusses findings related to oxygen consumption and blood flow to respiratory muscles during maximal exercise.
- It analyzes conditions leading to high ventilatory work, including expiratory flow limitation.
Main Results:
- The oxygen cost of hyperpnea during intense exercise can exceed 15% of VO2max.
- Respiratory muscle blood flow may rival that of limb muscles during peak exercise.
- Conditions like high ventilatory requirements in trained athletes and mammals lead to ventilatory limitation.
Conclusions:
- Excessive ventilatory work during exercise may necessitate reflex vasoconstriction in locomotor muscles.
- This diversion of blood flow can curtail endurance exercise performance.