Most of the time we tend to breathe in and out through the nose. After all, the nose is the main entrance for breath. I generally recommend breathing through the nose-whenever it is practical and do-able-for everyday breathing.
The role of the mouth in breathing is that of a supportive portal. Sometimes it is impossible for us to breathe through the nose, so the mouth takes over. For instance, when your nose is congested with a cold, your only choice for survival is to breathe through your mouth.
Sometimes we need to take a big breath in a hurry and breathing through the mouth and the nose simultaneously is more efficient. As you’re swimming, you use only your mouth to take that big gulp of air. We tend to breathe both through our noses and our mouths when we need to catch a quick breath during the conversation. Don’t let ideas about breathing through the nose or mouth get in the way of what is efficient when efficiency is vital.
You may have noticed that some breathing exercises are accompanied by specific suggestions for breathing through the nose or breathing through the mouth. These recommendations are designed only for specific results. With your everyday activities, let breathing through the nose or the mouth be a natural reflex.
The most important thing to keep in mind is the fundamental importance of abdominal deep breathing. Focusing on the nose and mouth while breathing can cause the muscles in those areas to tense up anxiously, narrowing the breathing can cause unwanted breathing noises as if you are gasping for air. Even professional speakers and public personalities sometimes suffer from this air sucking syndrome.
Instead of focusing your thoughts on the nose or mouth while breathing, do this; Imagine the back of the nose where it meets the throat as the opening of a funnel. Deep breathing is the key.