Thanks to a commenter for pointing out the importance of nasal breathing. I added this to the running guide . It is something I wrote about and experimented with last summer, but had forgotten about. This is why I made a permanent page on running - so I can keep track of everything!
Speaking of nasal breathing, I read where Olympian runner Perry Fields uses nasal breathing. Here is a section from an article she wrote:
"So, let me briefly tell you how I begin my workouts. If you are a runner or participate in any kind of athletics, try this before you begin your game or work-out. I start by walking before my track workouts and before runs. I usually walk anywhere from 5 to 15 minutes. During the walk I breathe deeply in a steady rhythm, making sure during inhalation that I keep my belly relaxed and allow my diaphragm to expand to its fullest. On the exhalation I breathe out slowly and allow my belly to fully retract. Then, after walking, I begin jogging, but I make sure to jog slower than someone walking. (This type of jogging is an African approach I picked up from my fellow Ethiopian and Kenyan training partners. They do this as a ritual before any type of workout). The two slow movements of walking then slow jogging gives my body time to prepare on a cellular level.
It is important to note that I breathe only through my nose, which as some of you may know filters impurities from the air and can help regulate body temperature. Only during intense track sessions or intense long runs will my mouth ever be open. Even during hard workouts and long runs, I breathe only through my nose for as long as possible. Then, right after a hard interval on the track, I close my mouth and force myself to breathe through my nose using "low breathing." This helps me recover before I begin another interval, leaving my cells better oxygenated.
In beginning to work in this way I discovered that as the season progressed I was able to run my long runs at a six minute/mile pace (for those who don’t know this is a pretty brisk pace) for up to ten miles, with my mouth closed almost the entire time using "low breathing”! Though you may not be used to it, your body will adapt to breathing only through your nose. By just breathing deeply through your nose, you are decreasing your stress and allowing your body to progress physically on its own. So each time you run or work out in this way, you will notice yourself progressing in your own proper and unique way. Many people have the tendency to over train, which can actually undermine their performance. By practicing breathing through your nose and the other techniques I have described in this article, you are allowing your body to improve its performance in a healthy way that won’t lead to crashing later on."