So, what exactly is your diaphragm?
It is an upwardly curved, c-shaped sheet of skeletal muscle which separates the thoracic cavity – containing the heart and lungs & protected by the ribcage - from the abdominal cavity.
What is the diaphragm’s role during respiration?
The diaphragm is the most important muscle in respiration and functions during both inhalation and exhalation. When it is engaged, this is called deep or diaphragmatic breathing. When breathing this way, the belly also expands to make room for the contraction of the diaphragm.
During inhalation, the diaphragm contracts and draws down towards the abdominal cavity and the external intercostal muscles contact to expand the ribcage up and out. This increased volume of the thoracic cavity creates a vacuum effect which draws the oxygen-rich air down into the lungs for gaseous exchange* to take place.
During exhalation, the diaphragm relaxes and returns to its neutral position and the internal intercostal muscles relax dropping the thoracic cage down and in. This reduces the volume in the lungs but increases the internal pressure, which reverses the process and forces carbon dioxide rich air out of the lungs
Diaphragmatic breathing maximizes the amount of oxygen that goes into the bloodstream. It is a way of interrupting the 'Fight or Flight' response and triggering the body's normal relaxation response the lowering pulse rate and blood pressure.
When the diaphragm is not recruited – as it is possible to breathe without it engaging it, inspiration and expiration both occur due to muscle contractions from accessory muscles, but the amount of air drawn into the lungs is minimal.
Most people who breathe shallowly do it throughout the day and they are almost always unaware that they do it, or of the difference between it and diaphragmatic breathing. Sitting down, especially if hunched over, hugely impacts the diaphragm’s ability to function.
Accessory muscles of inhalation
Accessory muscles in exhalation
Serratus Posterior Superior
Serratus Posterior Inferior
This breathing pattern creates tension in other parts of the body and can lead to a lot of other problems. When we breathe with our chests, we use the muscles in our shoulders, neck and chest to expand our lungs. This can result in neck pain, headaches, jaw pain and even exaggerate tinnitus.
Our shoulders slump forward and our posture changes as well. Diaphragmatic breathing, on the other hand, can lower blood pressure, reduce heart rate, relax muscles, decrease stress, and increase energy levels. Deep breathing grounds us as well.
The effect that stress has on breathing
Stress changes breathing patterns due to the natural fight or flight response, instead of drawing a full breath down into the belly using the diaphragm, breathing is fast and shallow meaning the shoulders are used to increase and decrease lung capacity. Breathing this way can create, prolong and exaggerate the symptoms of stress as the balance of gases in the body is disturbed by hyperventilation.
Relaxed breathing in through the nose in a controlled, even way can settle the nervous system by restoring the balance of gases, and increase feelings of calm due to lowered blood pressure and heart rate.
Prolonged time with little use causes the diaphragm becomes weakened, meaning it’s easier to leave respiration to the already recruited accessory respirations muscles. However, these are already being constantly overworked trying to lift the rib cage for forced respiration, as well as having their own primary actions to complete. This leads to chronic tension around the neck and shoulders.
How to breathe using your diaphragm
To practice breathing from your diaphragm, lie on your back with one hand on your stomach and one hand on your chest. Breathe in deeply while pushing out your stomach as far as you can. The hand on your stomach will move out and the hand on your chest will remain still. When you exhale, you will feel your stomach pulling back in. Both your chest and shoulders should stay relaxed and still.
*Gaseous exchange is the process diffusion that takes place in the lungs between oxygen and carbon dioxide into/out of the circulatory system.