Related Experiment Video
Updated: Aug 11, 2026

A Rapidly Incremented Tethered-Swimming Maximal Protocol for Cardiorespiratory Assessment of Swimmers
Published on: January 28, 2020
An analysis of the factors limiting maximal oxygen consumption in healthy subjects
1Istituto di Biologia, Facoltà di Medicina, Udine, Italy.
Abstract:
The factors limiting maximal oxygen consumption (VO2max) in humans are analyzed according to a multifactorial model derived from the O2 conductance equation. The alveolar ventilation (VA) and lung O2 transfer (GL) are not considered to be limiting, at least at sea level in healthy subjects, because changes in VA and/or GL are not accompanied by changes in VO2max, due to the shape of the O2 dissociation curve. Thus, the limits to VO2max are shared between O2 transport by the circulation and a peripheral factor, including O2 transfer from capillaries to tissue and mitochondrial O2 utilization. In untrained healthy subjects at sea level, O2 transport by the circulation is responsible for about 70% of the overall limits, the rest depending on the peripheral factors.
Related Concept Videos
Factors Affecting Respiration
Special considerations while measuring oxygen saturation
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.
Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
Oxygen Transport in the Blood
Oxygen Requirements and Growth Patterns

