Have you heard the one about breathing in through your nose and out your mouth? While that may apply to low intensity activities such as meditation or yoga, it has no place, as far as I know, in running.
According to the text Physiology of Sport and Exercise by Wilmore and Costill, the need to breathe increases in direct proportion to the intensity of work. A mild workload such as walking prompts deeper breathing that expands the lungs. As the work becomes more difficult, the rate of breathing also increases.
With the exception of conditions such as asthma or emphysema, breathing should not limit the ability to exercise, even at hard efforts. The volume of air entering the lungs is not the problem- it’s the body’s inability to extract and use oxygen that causes breathlessness when you run fast (inspired air contains roughly 20% oxygen while expired air has about 16%).
Many people are under the false impression that the proper way to breathe while running is to inhale through the nose and exhale through the mouth. I call this “self-induced” asthma, since they are purposely limiting the volume of air delivered to the lungs. This technique has a negative impact on running performance similar to asthma, particularly as speed increases.
Runners should be inhaling and exhaling through both nose AND mouth to a set pattern or rhythm. According to running coach Jack Daniels, most elite runners breathe to a 2-2 rhythm. They breathe in while taking 2 steps and out while taking 2 steps. At an easy pace they may switch to a 3-3 rhythm. One problem with this approach is the habit of always inhaling or exhaling on the same footfall, which some experts believe could be a cause for side stitches. If that’s the case you should consider periodically switching which footfall you are exhaling on, or even changing your breathing rhythm to exhale on alternating right and left footfalls. That gets a little tricky, since you’ll have to adapt an uneven 3-2 or 4-3 breathing pattern (breathing out for more counts than breathing in).
According to DePaul University Track Coach Bill Leach, uneven breathing cycles are effective because pressure within the lung is lower than the atmosphere, causing air to rush in quickly. You’ll want to take a little longer to exhale, since leaving residual carbon dioxide in the lungs can impede the delivery of oxygen on the next inhale.
Fortunately, running at marathon pace does not put you into oxygen debt, however an efficient oxygen delivery system certainly doesn't hurt. The fitter you are, the closer you'll be able to run your marathon at what is called "anaerobic threshold" pace- the intensity where you'll notice breathing becomes labored.
You should be perfecting your breathing rhythm on your long interval and tempo days, running just under or right at your anaerobic threshold. If you are having problems, it will help to practice your breathing pattern while walking before you start running. Over time your new breathing pattern should become second nature.
(c) Dave Elger 2008, All rights reserved