Deep breaths really bring relief

Human lungs are covered from the inside with the thinnest layer of a substance that reduces surface tension. Without it, the alveoli — the smallest air bubbles through which oxygen is exchanged — would simply stick together with each exhalation.

In newborns, especially those born prematurely, this substance is often produced in insufficient quantities, which leads to respiratory failure. Since the late 1980s, doctors have managed to save thousands of babies by injecting an artificially produced mixture of this substance into the lungs.

However, such treatment does not work in adults. The ETH Zurich researchers decided to figure out why — and found out that it’s not just about chemistry, but also about the physics of respiration.

The team, led by Professor Jan Vermant, investigated how the pulmonary fluid behaves when stretched and compressed — that is, when inhaling and exhaling.

It turned out that over time and with shallow breathing, the structure of the film is disrupted: the upper layer becomes tougher, and the lower ones become softer, and this interferes with the normal expansion of the lungs.

But when a person takes a deep breath, a kind of reboot occurs: the film stretches, the composition of the upper layer changes — it is enriched with lipids, becomes more dense and returns to its ideal state.

“It is this physical transformation that explains the feeling of lightness in the chest that we experience after taking a deep breath,” explains study co—author, graduate student Maria Novais-Silva.

Scientists note that with constant shallow breathing — for example, during sleep, stress, or a sedentary lifestyle — the elasticity of the lungs gradually decreases. This makes breathing less efficient and can contribute to the development of chronic problems over time.