According to the book "Breath" by James Nestor, elite athletes were able to improve their performance by nasal breathing at all times. Apparently this innovatio

According to the book "Breath" by James Nestor, elite athletes were able to improve their performance by nasal breathing at all times. Apparently this innovation made a big impact at one of the Olympics, and has been part of training regimens ever since. Oral breathing during exercise is a crutch for the body.