Is Nasal Breathing a Good Metric?

i was told once that nasal breathing is a good gauge of whether you're like, below your arobic threshold. i found as an interesting, maybe teaching tool, if possible. The calvia with that, i would say, is that it's going to take some practice to do nasal in and nasal out. I did a bunch of training on it for about eight weeks before doing this interview. How can we improve our performance? Share your story at CNN iReport.