I thought I'd add my 2-cents
I thought I'd add my 2-cents to this topic.... For the past few years I have been diagnosed with exercise induced asthma (EIA)... Anytime I work out, my breathing issues arise; I get wheezy and cough... And it is getting worse, now I am at a point where just talking to people for a while will bring on these issues. Sometimes I will eat a meal, and right afterwards I get wheezy, and can't figure out what foods trigger it. Its crazy, and it came out of no where.
Over the summer I read Doullard's book, "Mind, Body and Sport" and I have been doing the nose-breathing technique ever since, with very positive results. I had to scale back my efforts, as his book suggests that you train around 50% of your Max HRM... so I try to keep my heart rate around 125 or so. Supposedly if you keep training at this pace, you will get faster and faster, and you aren't really putting out that much effort.
The other thing Doullard is suggesting is that this breathing method is like doing yoga, and gets your mind off of the running and focused on your breathing; and you get "In the zone." I have experienced this here and there... where you suddenly come out of this "trance" and realize "Wow, I just ran a mile....." and you felt like you just hovered, instead of ran. I NEVER was able to do this when mouth-breathing, generally at a much harder effort/pace.
I thought it was interesting that his book did mention the 180 bpm pace, which I read often on barefoot running sites, like this one. I read this book and "Born to Run" in the same time-frame and was really inspired to get out there! The only thing about Doullard's book that I didn't follow that much of was what foods to eat for certain types of people, at certain times of the year... too complex for me.
I am still on the hunt for the root-cause of my breathing issues, actually getting an endoscopy to see if GERD/Acid Reflux is the cause of it on Wednesday. But for now, I will keep nose-breathing. Spin class and nose breathing is quite the challenge, but I am able to do it for about 90% of the class. During my 1/2 marathon I was nose-breathing, and I was very calm, relaxed, and with VFF's on, people were probably wondering what planet I was from.
But all in all, this book made me realize that nose-breathing is key for me, if I sleep/talk/workout with my mouth-open, I end up with the wheeze... so I shut my mouth as much as possible.