What is the best way to breathe while running?

you should breathe in through your nose and out through your mouth

Answer I've always been taught not to breathe in through your nose and out through your mouth. While this is the best way to breathe after you've exercised, to catch your breath, your nose simply can't get enough air into your lungs while you're exercising and your body's demands for oxegen are increased. Breathing in and out of your mouth is recommended during exercise.

A good breathing technique to use for a relaxed run is the 3:2 ratio, i.e. you inhale for 3 steps and exhale for 2. If you are running hard or fast, use a 2:1 ratio- you breathe in for two steps and out for one. These breathing techniques will prevents injuries and cramps. While running, you hit the ground with greater force during exhalation. These breathing patterns make sure you exhale on alternate footstrikes each time, thus balancing the stress to both sides of your body.