On Breathing (Read 1193 times)

Breathing accomplishes two major things in terms of gas exchange. The one we all think about is bringing oxygen into the bloodstream. This is not really changed substantially by breathing pattern or technique. Rather, the major contributors are oxygen concentration in the air and the partial pressure of the air itself. The second task that breathing accomplishes is removing carbon dioxide from the lungs. Carbon dioxide is the gaseous waste product that is produced as your body metabolizes energy. Carbon dioxide is an acid in the blood and your body needs to expel it. The way it does this is to release it into the lungs, where you then exhale it. If you exhale it too slowly, it can build up in your blood. If you exhale it too quickly, its levels can drop low (this is the classic hyperventilation people get, and the reason why you breathe into a bag is to rebreathe some of the carbon dioxide so it goes BACK into your lungs and blood). Carbon dioxide removal from the lungs CAN be altered by breathing technique, and breathing technique is about the only way you can change it. Do we breathe to keep our alveoli open? Does that increase our oxygen absorption from the air? Well, no, not really. Our lungs and surrounding muscles, etc, are well designed/evolved to keep our alveoli open and reasonably well oxygenated already. The reason is this: unexpanded alveoli are as useless as the appendix and are a risk for infection, so the body preferentially keeps all alveoli open to some degree. It IS however the case that most of the air you inhale does NOT make it to your alveoli. Most sits in your trachea or bronchi, moving in and out. The oxygen that gets to your alveoli gets there more by passive diffusion and turbulence from the bronchi than it does from direct pulling all the way down. This is a useful image: Most relaxed breathing occurs in the tidal volume range. A very very very deep breath will allow you to inhale to the inspiratory reserve volume and exhale out the expiratory reserve volume, the span of which makes up the vital capacity. So normal relaxed breathing occurs with a tidal volume and deep forced inhalations and exhalations occur over your vital capacity. Breathing at your vital capacity does NOT normally increase oxygenation but DOES increase ventilation. However, if you have certain lung diseases, breathing at your vital capacity CAN increase your oxygenation. The reason you likely feel better when breathing deeply during exertion is that you are ventilating your carbon dioxide away. High concentrations of carbon dioxide, as can build up during near-threshold exertion, can make you feel lightheaded, weak and breathless. Deep breaths into your expiratory reserve volume can drive off the excess carbon dioxide and make you feel better. In fact, it is the buildup of carbon dioxide more than the initial absence of oxygen that makes you uncomfortable when you hold your breath. If you don't believe this, ask your doctor to monitor your "pulse ox" (i.e., the oxygen concentration in your blood) while you hold your breath. If you hold your breath until you burst, your oxygen concentration will remain largely unchanged but your heart rate will increase and you will get very uncomfortable. Test your blood and you will find that your carbon dioxide will have increased a bit. This, by the way, is also how carbon monoxide kills people. The carbon monoxide replaces oxygen so that less and less gets absorbed from the lungs and delivered by the blood to the body. Over time (minutes to hours) the body becomes severely oxygen deficient without the victim realizing that anything is wrong. Until they slip into a coma or die. So low oxygen concentration usually can be fairly painless. Low oxygen concentration, of course, is distinguished from low AIR pressure, as occurs in the mountains. In that case, all of the gasses in the air are reduced and oxygen remains at 21%. The breathlessness in that case is because the lower pressure means that less air overall is diffusing into your lungs and then into the bloodstream. Your body will compensate over time by altering your heart dynamics and then, eventually, your red cell concentration.

So, Doc, in terms of practical recommendations for us simple runner types, would you recommend inhale then exhale? Or exhale then inhale?

I find breathing to be a most excellent habit, and I encourage most (but not all) of my fellow citizens to do it whenever possible.

Sure. But as has been pointed out, is it better to inhale or exhale? And does this change if you are in elected office?

Depends on what your definition of "is" is. (If that is not one of the most concise examples of what "spin" is, then I'm a monkey's uncle).

Studies have shown that those who breathe improperly live longer than those who don't breathe.

Look up the respiratory system of birds. Feel enormous envy. When I'm nearing the top of an 18% grade slope, standing on my pedals, wishing I could inhale through my ears and butt as well as my mouth and nose, I curse the birds for their efficiency. did