Nasal breathing during exercise has gained attention for its potential benefits on athletic performance. It's believed to improve oxygen uptake, increase CO2 levels in the blood, optimize breathing mechanics, and enhance endurance. By breathing through the nose, athletes can better regulate their breathing rate by increasing their CO2. This allows for a more steady flow of oxygen to the muscles, leading to improved performance and recovery.

In particular, CO2 tolerance must be increased in order to quantify the increase in performance.