I’m a big fan of breathing, both as an endurance athlete and in my daily life. Sucking in oxygen and exhaling carbon dioxide are both absolutely vital to health and performance. But what I don’t know, even after decades as an athlete and years writing about sports science, is whether it’s possible to breathe better.
The standard take on the human respiratory system is that it’s overbuilt, meaning that it’s never the limiting factor in your ability to sustain exercise. Sure, you’ll breathe heavily if you run a 5K race—but even if you were magically able to breathe 5 percent harder, you wouldn’t run any faster, because the real limiters are the beating of your heart, the circulation of blood, the metabolic byproducts accumulating in your muscles, and so on.
More recently, though, researchers have concluded that there are situations where the respiratory system—the upper airways of the nose and mouth, the lower airways leading to the lungs, along with the lungs themselves and the muscles powering them—struggles to meet the demands placed on it. Most notably, for our purposes, highly trained endurance…
