The work of breathing is the energy the respiratory system must expend to ventilate the lungs, and it decomposes into elastic work — overcoming the lungs' intrinsic tendency to collapse, governed by compliance and surface tension — and non-elastic (resistive) work, expended against airflow resistance and tissue friction. Plotting pressure against volume over a breathing cycle yields a pressure–volume loop whose enclosed and bounded areas quantify these components separately, with the inspiratory and expiratory limbs tracing distinct paths and the hysteresis between them representing resistive work. Because total work is the sum of an elastic component that rises with tidal volume and a resistive component that rises with breathing frequency, there exists an optimal respiratory rate minimizing total work; shifts in either component predict the compensatory breathing pattern adopted, so this concept belongs to pulmonary mechanics within respiratory physiology and links lung mechanical properties to ventilatory control.
The work of breathing is the energy the respiratory system must expend to ventilate the lungs, and it decomposes into elastic work — overcoming the lungs' intrinsic tendency to collapse, governed by …