Question: I go to a gym regularly. I am riding at full speed and try keeping my mouth shut. It works out pretty well. BUT then I go into a leader-led group, and the instructor is constantly telling me that I have to exhale through my mouth. I ignore it. Is there any reason for thinking panting is good? The only advantage I see is that with open exhalation I do not have to blow my nose that often! After all, I manage it quite well, so why change a concept that works. However, I want to know why it is good to exhale through your mouth.
Answer: My view is that the knowledge of breathing inside the work out world often has room for improvement. I would start by asking your instructor what he or she thinks are the most important benefits of exhaling through your mouth.
The benefits of exhaling through your nose are, as I see it, the following ones:
• You will retain more water. A Swedish study shows that 42% more water will leave a body when you are exhaling through your mouth compared to through your nose.
• You will retain an optimal carbon dioxide pressure. The same study also shows that the breathing volume increased by 12% when you are exhaling through your mouth compared to through your nose, which means that the outflow of carbon dioxide also increased. A reduced carbon dioxide pressure in the blood results in a poorer oxygenation of your muscles (the Bohr effect). As carbon dioxide also has a widening and relaxing effect on the muscles in your blood vessels, it is more difficult for the blood to reach your muscles. A lower carbon dioxide pressure is probably a major reason why many people feel that conscious breathing during exercise gives a lower heart rate.
• Your nose will be reheated and moisturized. If you exhale through your nose, your nose is moisturized and reheated by exhalation air from your lungs, which is 100% saturated with water vapor and warmed to 37° C (98.6° F). If you exhale through your mouth, your nose will eventually work worse as it gets colder and drier.
• You will clean away bacteria. Particles and bacteria that are trapped in your nose when you inhale will disappear if your exhale through your nose. If you also breathe in through your mouth, you will skip your body’s first line of defense against external intruders (your nose), and more particles and bacteria will end up in your lungs. This will create inflammation, and your lungs will have to produce more mucus to get the particles out. Both of these things will contribute to narrower air passages.
• The oxygenation of your blood will be more efficient. As your nose has a narrower passage compared to your mouth, a higher pressure is maintained in your lungs if you exhale through your nose compared to if you exhale through your mouth. It will provide a more efficient transfer of oxygen from inhalation air to your blood and carbon dioxide from your blood to exhalation air.