Anatomy of Breathing

Author: Craig Coghlin CPT (Canfit Pro), CFC (CSEP)
For anyone who has ever worked out with a trainer, myself especially, they have likely been drilled on the importance of breathing while lifting. “Exhale on the concentric phase and inhale on the eccentric phase!” “Never hold your breath!” For those who simply take our word and obey by our ranting, thanks for your trust. For those who have asked why we insist on these practices, this article’s for you!

The extreme basic reason for breathing is as follows: we don’t really want you to die on us when we’re training you. Breathing allows for the exchange of oxygen and carbon dioxide between your body and the outside world. If you don’t breathe, you die; it’s that simple.

But many insist on holding their breath while performing maximal effort lifts. While it is highly unlikely that you will die, it is still not a good practice. Breath holding during training is called a Valsalva maneuver. It involves the closing of the glottis (the flappy-type thing that controls air into the vocal cords), an increase in intra-abdominal pressure, and an increase in intra-thoracic pressure (chest cavity). This causes the air trapped in your lungs to become quite pressurized, and it restricts venous blood return. This, in turn, decreases the cardiac output (the amount of blood the heart kicks out in a minute), and subsequently creates an increase in blood pressure. All of this can contribute to that dizzy feeling you get after finishing an intense set, and thus, does no good whatsoever. So simply stated, don’t do it

Something that can be considered opposite to a Valsalva maneuver is hyperventilation. Hyperventilation can be induced by exercise anxiety or respiratory disorders, which create an increase in breathing that is well above what the body needs. This causes carbon dioxide levels to drop significantly, which can lead to light-headedness or unconsciousness.

Carbon dioxide levels are tightly regulated within the blood, so the body responds in different ways to even the slightest variations in these levels. An increase in carbon dioxide (which creates increased acidity in the blood – bad), with no adjustments made by the body creates that panicky feeling of being short of breath. This is referred to as dyspnea and can be caused by poor respiratory muscles.

Well that’s all fine and dandy, but why is it that we stress exhalation on the concentric phase (muscle shortening)? There are very few studies on this (in fact, I couldn’t find any). The best explanation that I can think of would be that is simply feels more natural. If you were to inhale when you were supposed to exhale, blood pressures would not differ, but your heart rate response would increase as compared to exhalation. In addition, it’s easier to grunt out that last rep when you’re exhaling. The respiratory physiologists I questioned on the topic had no resources for the question, so if anyone has a scientific explanation for this, please, let me know.

But for now, it’s just best to listen to your trainer. Happy grunting!