Often the changes in responsiveness of the muscles and nerves are subtle. Even when the effects are quite noticeable, it can be hard to determine what has gone awry. Even after we have identified an area of dysfunction, it is a challenge to imagine how it started, what all its consequences might be, or what might be done to make it better.
Unravelling these unnatural patterns, whether they are subtle or obvious, requires a mind capable of intense concentration. Conscious breathing allows that kind of concentration to happen.
The body accomplishes many functions without any conscious effort. Breathing is unusual because it can be done consciously, or we can just let it happen without any thought. Conscious breathing is an exceptionally important part of body awareness because it influences the body’s involuntary functions (those that are done without conscious input). For example, conscious breathing lowers blood pressure and slows the heartbeat. The involuntary systems respond to conscious breathing by relaxing the body. Once the body is relaxed, we can feel safe and find a state of mind where the distractions of everyday life fade away. We are better able to patiently observe details arising from the sensations on which we are concentrating. The science that explains this involves the interaction between and balancing of the sympathetic and parasympathetic nervous systems, including the role of the Vagus nerve. See https://drarielleschwartz.com/vagus-nerve-yoga-dr-arielle-schwartz/#.WyagtadKhPY
The single most important step in developing a body awareness practice is mastering the art of making a soft sound while breathing. This skill adds an entirely new dimension to our efforts to consciously control our breath. The sound should be just loud enough for us to hear it, both on the inhale and the exhale. The soft sound makes it easier to notice how long inhalations and exhalations are, how long the pauses are between breaths, whether the breaths are steady or wobbly or deep or shallow. That information opens the door to notice how the body moves on inhalation and exhalation and which muscles are engaging and which are relaxing on each side of the breath. There is much to explore about feeling the body breathe.
Breathing through pursed lips, as if sipping and blowing the air through a straw, is an easy way to make the sound. This is a place to start with breath sound. A more helpful way to produce the soft sound is by engaging throat (not neck) muscles to constrict the air passage (i.e., partially close the glottis) while breathing in and out through the nose. These are the same muscles we use to cough when we are in the audience at a public gathering. The sound is like a whisper but with closed lips. Some describe it as an ocean sound, distant waves rolling up on the shore.
Just reading an explanation of how to make this sound cannot convey the powerful effect this skill has on our ability to breathe consciously and the subtly of the information we can gather using it. The importance of this kind of breathing in yoga is reflected in its name: Victorious Breath (in Sanskrit, Ujjayi). Put Ujjayi in a search engine and learn more about this ancient practice.
In addition to using sound to track the breath, Ujjayi breathing changes the way air is delivered to the lungs. Having the glottis partially closed is similar to using a thumb to change the stream of water coming out of a garden hose. With a partially closed glottis we can slow the stream of the air and limit its flow. This allows the lungs to fill slowly, expanding beyond breathing areas that we use when breathing automatically. In addition, the sound caused by partially closed glottis is a vibration that stimulates the Vagus nerve as it passes through the throat. The Vagus nerve is important in the function of the parasympathetic nervous system. This adds to the calming effect of conscious breathing.
With a focused mind and a relaxed body that conscious breathing cultivates, we may feel something like “energy” moving in and around and through our bodies. This is an awareness of the nervous system doing its work in muscles and organs. Yoga and other systems recognize this sensation. It is variously called “life force” or “prana” or “chi”. It is a real sensation and is worth exploring.
Take advantage of the relaxed state that accompanies conscious breathing. Let the quiet mind sense and reflect on the details of the body’s sensations.