Related Experiment Video
Updated: Jul 16, 2026

A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Effect of voluntary respiratory efforts on breath-holding time
I Mitrouska1, M Tsoumakidou, G Prinianakis
1Department of Thoracic Medicine, University Hospital of Heraklion, 711 10 Heraklion, Crete, Greece.
Introduction:
Near the end of a maximal voluntary breath-hold, re-inhalation of the expired gas allows an additional period of breath-holding, indicating that the breaking point does not depend solely on chemical drive. We hypothesized that afferents from respiratory muscle and/or chest wall are significant in breath-holding.
Methods:
Nineteen normal adults breathed room air through a mouthpiece connected to a pneumotachograph and were instructed to breath-hold with and without voluntary regular respiratory efforts against an occluded airway.
Results:
Fifty one trials with and 53 without respiratory efforts were analyzed. The mean number of efforts per minute was 19+/-2.3 and the mean lowest airway pressure (P(aw)) -16.6+/-5.4 cmH(2)O. Breath-holding time (BHT) did not differ without (33.0+/-18.2 s) and with (29.3+/-12.3 s) efforts. In five patients arterial blood gasses were measured before and at the end of breath-holding and they did not differ between trials without and with efforts, indicating similar chemical drive. Our results suggest that afferents from respiratory muscle and/or chest wall are not the major determinants of BHT.
Related Concept Videos
Other Factors Affecting Respiration Centers
However, the ability to hold one's breath voluntarily is not limitless. When the CO2 concentration in the blood reaches a critical level,...
Mechanism of Breathing II: Expiration
Expiration, or exhaling, is a complex physiological process that begins as the inspiratory muscles begin to relax. This relaxation triggers a series of events that epitomize the efficiency of the respiratory system.
Mechanism of Expiration:
Pulmonary Ventilation: Inhalation
Boyle's law becomes particularly pertinent when examining respiratory...
Hyperpnea and Hyperventilation
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...
Mechanism of Breathing I: Inspiration
The respiratory system, an essential network for breathing, comprises the conducting and respiratory zones, each playing a crucial role in the overall process of respiration. Let us explore the detailed mechanism of inspiration, or inhalation, which is the first phase of the respiratory cycle.
Pathway of Air during Inspiration
During inspiration, air enters our body through the nose or mouth and moves through the conducting zone,...
