Pulmonary system limitations to endurance exercise performance in humans

Area of Science:

• Exercise Physiology
• Respiratory Physiology

Background:

• The pulmonary system is increasingly recognized as a critical determinant of whole-body endurance exercise capacity.
• Understanding respiratory limitations is key to optimizing athletic performance.

Purpose of the Study:

• To review the mechanisms by which the respiratory system limits oxygen transport during strenuous endurance exercise.
• To highlight how these limitations affect oxygen delivery to locomotor muscles and contribute to fatigue.

Main Methods:

• Review of existing literature on respiratory system function during exercise.
• Emphasis on three key mechanisms impairing oxygen transport: arterial oxygen content, leg blood flow, and respiratory muscle work.

Main Results:

• The respiratory system often fails to prevent arterial desaturation, reducing oxygen content (C(aO(2))), particularly in trained athletes and women.
• Fatiguing respiratory muscle work (W(resp)) causes vasoconstriction, compromising leg blood flow (Q(L)).
• High-intensity exercise (>85% VO2max) and altitude exacerbate these respiratory limitations.

Conclusions:

• The healthy pulmonary system can impair locomotor muscle oxygen transport during strenuous exercise.
• Respiratory limitations compromise endurance performance by reducing oxygen delivery and increasing fatigue.