3. Take a Deep Breath In: The Mechanics of Inhalation

In this document, we will focus on the exhalation phase of breathing, and learn why an extended exhale is the key to relaxation, focus, and all the other benefits of mindful breathing. But it is first worth taking a quick detour into the mechanics of inhalation.

As a quick aside/experiment, if you happen to have some balloons handy, take one and blow it up with one breath as big as you can. Then, at the end of this chapter, blow up another balloon and see if it is bigger. While a bag of balloons is likely not standardized so that each balloon is exactly the same, this can be a fun thing to try. I almost always find that the second balloon is quite a bit bigger.

(3) Emily and Her Balloons, May 2015

Our lungs sit within the thoracic (chest) cavity. Expansion and contraction of that cavity, using our inspiratory breathing muscles, also makes the lungs expand and contract. There are three major sets of those breathing muscles that can expand that rib cage and cause inspiration. The diaphragm is the most important.

(1) The diaphragm is a dome-shaped structure of muscle and connective that sits at the bottom of our rib cage, below the lungs. When it contracts, it pulls downward, causing us to inhale. When it relaxes, it is passively pulled back up into the rib cage. The diaphragm moves the most air of any muscle group, and it is mechanically the most efficient breathing muscle. When we are calm, it is the diaphragm alone that moves. If you watch someone, especially a baby, sleeping, you can see only the belly going in and out. Diaphragm breathing is thus sometimes called “belly breathing”. Wikipedia has a nice animated .gif in its diaphragmatic breathing entry. Now please go ahead and try a few slow, relaxed belly breaths.

4. Diaphragm (in Green), Wikipedia, John Pierce








(2) While the diaphragm alone is perfectly adequate for normal, relaxed breathing, we do have other breathing muscles. The diaphragm moves the most air, followed by the intercostal, or rib cage muscles. There are two sets of intercostal muscles, the inspiratory and expiratory intercostal muscles. In other words, one set of muscles expands the rib cage and the other contracts it. The contracting muscles generally don’t need to be used, since we can just relax and let the air out. But if we want to actively push the air out, faster than normal, we can use the expiratory rib cage muscles. Note that the diaphragm can’t push air out like this this, but the abdominal muscles can. The diaphragm and the abdominals form agonist/antagonist sets of muscles the same way that the inspiratory and expiratory rib cage muscles do (we will refer to them as chest muscles). Now go ahead and add chest breathing to your belly breathing. Inhale slowly with the diaphragm, then add the chest. Try it a few times. You’ll notice that the chest muscles inhale far less air.

5. Thorax (Chest) & Intercostal Muscles, Grey’s Anatomy












(3) The third set of muscles moves a very small amount of air, and these muscles are rarely used in breathing. There are the trapezius or shoulder blade muscles. If you raise your shoulders and shoulder blades, this act expands the rib cage, just a bit, and thus more air is inhaled. Shoulder breathing is an inefficient and stressful way to breathe. But go ahead and try it. You won’t be able to move much air. Now go ahead and add shoulder breathing in sequence to the other two breathing muscles. Diaphragm, chest, and shoulders. Try it a few times.

  1. Scapulas (Shoulder Blades) & Trapezius, Grey’s Anatomy











There aren’t many situations you would breathe using the shoulders. There are only two I can think of. One is when you really need a full, maximal inhalation. This could be the last big breath you take for a freedive. It could also be before trying to blow out the candles on a birthday cake in just one breath, but its hard to imagine you would really need that small amount of extra air. The more likely, but still very unlikely, scenario is if you have your diaphragm temporarily cramped or spasmed, in other words, when you have the “wind knocked out of you”. Perhaps once or twice in your life you may have taken a blow to the area right between the thorax and abdomen while running around the playground or playing sports. When you get the wind knocked out of you, you have taken a blow to the solar plexus, which is a bundle of nerves and muscles in that region of the body. Such a blow can cause your diaphragm to cramp up, and thus inhibit your ability to breathe for several seconds. This can be quite concerting and cause a suffocating feeling, particularly because one is typically in a state of exertion at such a time. The solar plexus is associated with the Anahata chakra.

7. Chakras (yoga energy centers), Wikipedia, William Vroman









If you listen to such a person trying to breathe, you will typically hear a struggling, wheezing type of breath. This is because the person us breathing only with the chest and shoulder muscles, which tends to create a wheezing noise as one is trying to take a deep breath with muscles that can only take small breaths. If this ever happens to you, try to relax, realize that the diaphragm spasm will soon pass, and take comfort knowing that you can breath with your other muscles, just less efficiently.