One of the more important aspects of running is the proper way of breathing. Running is not just about the legs and thighs and feet. It is also about the lungs and how to bring greater amounts of oxygen into the system efficiently.
Unnoticed by many, even by the athletes themselves sometimes, the nature of your breathing during your running affects your performance. Those runners who can correctly deliver oxygen into their system are stronger than their counterparts who struggle when they are running because they do not know the technique.
One training technique is to breathe slightly slower than your body requires when you are not running. This starves your system for oxygen and forces the heart to beat faster.
After a time, the body learns to compensate for the lack of oxygen so that when this technique is not in use, your body is already more efficient in processing your breathed air. This is demonstrated in swimming.
Swimmers do alternate breathing which is breathing every third stroke. This enables them to breathe on alternate sides without taking a breath with every stroke.
At the start, their body demands more oxygen, but will learn to adjust to the decrease in oxygen. In time, the body becomes more efficient in processing the limited air. Runners who swim often have excellent breathing efficiency.
Sometimes, in long races (or even those short races) a runner may lose focus and is thrown out of his breathing rhythm. It could be caused by the simple forgetting to concentrate on the breathing or its pattern.
One way to avoid this is for the runner to time his breathing in rhythm with his steps. This is like the style of the swimmers who breathe at every third stroke.