Something most of us take for granted is our “breathing.” That is, until we can’t breathe. This necessary act for sustaining life by our nervous system is actually the foundation of our body’s movement system. The famed Czech researcher on human movement Dr. Karl Lewit states, “Respiration is our primary and most important movement pattern…and also the most dysfunctional.”
As a physical therapist who has specialized in movement dysfunction most of his career, I have always been aware of how breathing affects posture, alignment, and other bodily functions as well as its importance in treating musculoskeletal pain. However over the years, that fact has become more and more evident to me especially with my own personal, medical history of asthma. Therefore, I became motivated to write an article that presents an overview of the important act of breathing.
The human respiratory system is located in your thorax between the neck and abdomen. The thoracic wall consists of skeletal (bony) and muscular components, extending from the first rib and the xiphoid process of the sternum (breastbone) superiorly to the 12th rib inferiorly.
The respiratory system can further be classified in terms of its function and anatomy. Functionally, it is divided into two zones with the first being the “conducting zone” that extends from the nose to the bronchioles of the lungs serving as a pathway for conduction of inhaled gases. Secondly, is the “respiratory zone” where it is the site of gaseous exchange comprised of the alveolar duct, alveolar sac, and the alveoli of the lungs itself. Anatomically, it is divided into the “upper respiratory tract” starting at the nose and ending at the larynx (voice box) and the “lower respiratory tract” that continues from the trachea (windpipe) to the alveoli of the lungs.
Because there is usually some confusion, I will first clear up the distinction between breathing and respiration. Breathing is the actual, physical act of moving air in and out of your lungs while respiration is the physiological transfer of gas in the lungs and at the cellular level for production of energy by the mitochondria.
With each inhalation, your rib cage has the unique ability to move as a unit to increase its anterior/posterior (front/back) and lateral (side) dimensions simultaneously allowing for the movement of air in and out of your body. Visualize your ribs around the lungs as a “box” so when you breathe in, this box elevates and gets bigger. This occurs because of accessory breathing muscles that will be discussed later, but the first structure that comes to mind when talking about breathing is the “diaphragm.” It is the diaphragm, one of the coolest muscles of your body, that functions as the primary breathing muscle as well as playing a foundational role in maintaining your skeletal posture and “core” stability.
Simply put, the diaphragm is mainly responsible for the generation of negative intra-thoracic pressure within the chest cavity that drives the movement of air, lymph, and blood throughout your body. The act of inhalation (breathing in) causes the diaphragm to contract and move inferiorly toward your feet losing its dome shape. This action causes a decrease of pressure in the thorax (body cavity enclosed by ribs) allowing air to be taken in by the lungs. As you exhale (breathe out), the diaphragm relaxes with its dome shape being restored causing the air space within the lungs to be decreased forcing air out.
Anatomical breathing refers to the natural extension and flexion motion of your body and spine in the sagittal plane with each breath. Extension of the lumbar spine (increased lordosis) facilitates inhalation and flexion (loss of lordosis) facilitates exhalation. As the body gets compressed in flexion, exhalation dissipates the intra-thoracic pressure while extension assists in opening the thoracic area to facilitate inhalation.
There is a biochemical aspect of respiration that also needs to be mentioned which is all about “gas” exchange. In other words, getting O2 in and CO2 out of your body in order to maintain the O2/CO2 balance of your blood. This physically occurs both at the lungs and at the cellular level with “cellular respiration” where the cells use O2 as part of a process to produce ATP (energy) and getting rid of its byproduct CO2.
Chemical receptors in the body constantly monitor your blood pH (acid vs alkaline) that will adjust your breathing rate automatically to a normal blood pH since the body is trying to achieve homeostasis. When you experience someone who is hyperventilating (over-breathing), one is actually blowing off too much CO2 causing what is referred to as “alkalosis.”
While we do have conscious control over this subconscious system of breathing, the reflexive physiological controls of the body and brain will alter breathing automatically to “get what the body needs” regardless of what you consciously “think” your body needs.
In addition, keep in mind that breathing has a psychophysiological impact that is significant. Remember the autonomic nervous system (ANS) which is part of the central nervous system (CNS)? Again, it is broken down into the sympathetic system which is referred to as “fight or flight” aspect and the parasympathetic system which is referred to as the “rest and digest” aspect.
As with most functions of the human body in its design, it is very clear that the physiology and psychology of breathing are integrated. When someone feels anxious, the ANS reflexively produces a distinctive pattern of upper chest, shallow breathing. This modifies the blood chemistry leading to a chain reaction of effects that will induce anxiety and reinforce this dysfunctional pattern which initially produced the pattern of breathing in the first place. That is when relaxation techniques utilizing deep breathing can help.
Your involuntary respiratory action (inhale/exhale) works in close coordination with what is popularly referred to as your body’s “core.” That part of your structure that stabilizes the thorax and pelvic girdle with your posture and movement while providing the internal pressures to expel substances from your body with the “valselva maneuver.” Keep in mind that the core also contains the location of your body’s center of gravity (COG) which is so vital in determining how your skeletal structure reacts to the forces of gravity and its effects during the activities of your daily living.
Because of the body’s core intimate relationship with breathing, your skeletal structure, and its COG, anything that weakens the function of the diaphragm also adversely affects the thoracic spine and rib cage function once again showing how the human body is so integrated. When there is a shift in your body’s COG, the joints of the body will stiffen and ultimately affect how you breathe.
It doesn’t matter what you are doing whether participating in competitive sports or just taking out the garbage, the core muscles must be properly engaged. They must create the ideal tension in order to produce skeletal stability and a normal breathing pattern. Because dysfunction in any respiratory-related structure we discussed makes you more susceptible to musculoskeletal pain and injury, restoring ideal “core” function cannot only reduce your musculoskeletal pain that you see me for, but also reduce the metabolic (energy) cost for your activities of daily living. That is because your breathing, posture, and movement become more efficient.
When an imbalance of tension, trauma and poor posture alter the biomechanics that undermine smooth integrated core movement, it becomes easily detectable during your gait (walking) and other functional movements. When I evaluate an individual in my clinic, I not only see the compensation, but I can actually palpate and feel the dysfunction involving the bony structure, muscles, and fascia (connective tissue).
Due to the fact that uncoordinated movement is stiff and less efficient, it alters the body’s loading and unloading and muscle activation patterns to gravity and its effects. As a result, there is a loss of the natural “flow” to movement. Just observe people walking today with many demonstrating a gait pattern that is more side to side rather than its natural flow you should see. Because of “movement amnesia” or “muscle memory,” many are unable to describe or feel these alterations with their compensated posture and movement.
Anatomically, the isolated rib cage and core should work together as a unit that is essential to regaining the natural flow of human movement. Pain oftentimes is manifested when an isolated rib loses its ability to properly coordinate movement with the rest of the ribs and spine as part of that functional unit. I know many of you have been treated by your chiropractor because of a rib being out of alignment. A good analogy for this lack of coordination between the ribs and spine would be a rowing team where one oarsman uses her/his ore out of sequence with the whole group.
Altered rib function by itself can cause difficulty in breathing, restricted shoulder movement, referred pain to other areas, and reactionary or reflexive muscle guarding. Additionally, ribs out of alignment can pinch intercostal nerves, sending pain through the length of the rib and occasionally, to the chest wall creating anxiety about a possible heart attack.
I cannot emphasize enough the influence that your thoracic spine, rib mobility, and overall postural stability has on your breathing. Think about it! The diaphragm, intercostals, abdominals, and accessory breathing muscles produce upward to 21,000 breaths a day. Talk about repetitive movement! But with a strong, “freely” moving diaphragm serving as the primary muscle for respiration, the intercostals and the accessory muscles are able to remain soft and relaxed allowing for a normal breathing pattern.
In my clinic, I see many clients with upper thoracic spine restrictions such as with a dowager’s hump or increased thoracic spine kyphosis causing them to breathe primarily with the scalene or lateral neck muscles that attach to the first and second ribs. As these neck muscles eventually fatigue, the alignment of the atlas (C1) and axis (C2) can become altered causing a chain reaction that can change the alignment of the entire skeletal structure. Once again, it’s all connected.
Outside of the diaphragm, there are other muscles such as the intercostals that directly impact breathing. These are small muscles located between each rib and are often a forgotten piece of the puzzle in breathing. They are very active in breathing, pulling the ribs closer together in inhalation and during forced exhalation. These muscles live up to their name by covering the short and vertical distance between any two ribs running from T1 to T12. The intercostals span the ribs and associated cartilages from the sternum in front and wrap around nearly to the transverse processes of the spine.
There are actually three layers of the intercostals on each side of the body that include the external, the internal, and the innermost. These three layers correspond facially to the abdominal layers which we will discuss consisting of the internal and external obliques and transverse abdominis. Due to the fact that the innermost layer is irregular and follow the same line as the internal intercostals, I will focus just on the external and internal intercostals.
The external intercostals angle down and in just like the external oblique, a lateral abdominal muscle. They run similar to the direction of your fingers when you put your hands in your jacket pocket. They extend from where the ribs meet the transverse processes of the spine in the back all the way around to the ribs in the front ending where the bones end and the rib cartilage begins about an inch or three from the sternum.
Conversely, the internal intercostals angle down and back, and fill in the area between the ribs and the cartilages all the way from the sternum in front and around toward the back, ending around the angle of the ribs where they can no longer be felt a few inches from the spine. In short, the external intercostals are more in the back and the internal intercostals are more in the front, but they do overlap along the whole lateral aspect of the ribs.
To help you better understand the act of breathing, visualize your ribs around the lungs again as a “box,” so when you breathe in this box gets bigger. With the high dome of the diaphragm dropping down while breathing in, it moves the bottom of the box down to pull air into the lungs. The scalene muscles of the neck at the top of this box will hold it up not allowing it to go down with the action of the diaphragm which will pull more air into the top of the lungs.
The action of the external intercostals also play an important role in inspiration and elevation of the box which is dependent upon the fact that the ribs are naturally angled down at about 30º from back to front. Since the external intercostals are angled down, shortening them will pull the ribs up toward each other thereby lifting the sternum and the ribs as a unit and a “box.”
When you exhale, it is supposed to be an entirely passive action where the inherent elasticity of the lung tissue itself is thought to be enough to bring the diaphragm back up and the ribs back down. If you simply relax your breath out, the “box” will come down too. However, the internal intercostals using the reverse argument, could pull the ribs down and together which is presumably only necessary with forced exhalation.
When the diaphragm and intercostals, the primary muscles of breathing, are unable to move enough air in and out of the lungs, then additional or “accessory” breathing muscles are called into action. Overuse of these accessory muscles is the first sign of a breathing dysfunction.
The accessory muscles used when breathing in or raising the box include the anterior, posterior, and middle scalene, sternocleidomastoid, trapezius, and pectoralis major muscles. When these muscles contract, the so called “box” including the breastbone, upper ribs, and clavicles (collar bone) are elevated causing the upper part of the chest to rise.
By doing this action, the lungs get bigger allowing more air to enter. When a person is not taking in enough oxygen, the central nervous system of the body automatically or reflexively activates these muscles to a greater extent in compensation every time with inspiration.
Accessory muscles may also be used with breathing out or with expiration. Normal breathing out again is supposed to be a passive action that occurs naturally without the use of any muscles. It should occur when the diaphragm and outer intercostals relax, reducing the size of the lungs that forces the air out. When a person is unable to breathe out enough air, accessory muscles of expiration will become activated.
The main accessory muscles of expiration are your abdominal wall muscles comprised of four layers from the front and arranged from surface to deep. The deepest layer of the abdominals is the transverse abdominis, which traverses the entire abdomen from one set of lumbar transverse process to the other. Though it physically consists of two muscles on each side of the body, they often act as one, squeezing the belly like the squeezing of a toothpaste tube. This muscle is actually used to initiate emptying motions of your bladder, rectum, and stomach. And for the female species, the uterus. It holds the organs of our body in and up. Also, this squeezing movement is often times referred to as the “valselva maneuver” and can be felt most easily in the act of coughing. As a side note, the tone of the transverse abdominis has been shown to be very important in stabilizing the sacroiliac joint (SI joint) teaming up with the mulifidus muscles of the lumbosacral spine. Once again, emphasizing the integration of the human body.
Another abdominal muscle is the internal oblique that runs diagonally up and forward from the iliac crest of the pelvic girdle, tying it to the ribs on the same side and up via the external oblique to the ribs on the opposite side and even to the opposite hip, moving straight across the lower belly just like the transverse abdominis.
The external oblique, on the other hand, is a broad sheet of muscle which extends downward and forward to connect the lower ribs to the same side hip, the pubic bone, and the opposite hip via the internal oblique.
The most superficial of the abdominals is the rectus abdominis connecting the pubic bone of the pelvic girdle to the 5th rib on each side of the body. So as you can see, the abdominal muscles that make up the abdominal wall run vertically, diagonally, and horizontally. However when they contract as a unit, the diaphragm is pushed up into the chest, forcing more air out of the lungs.
The abdominal muscles are not the only ones that make up part of the body’s “core” impacting your breathing, posture, and movement even though they are the first thing most people think of when mentioning the body’s core muscles. While that may be true and on point that they need to be strong for stability of the body’s core, there is a lot more to it than just thinking of the abdominals. The word core itself implies that the muscles are deep and central.
Keep in mind that the anatomical structure that is deepest and most central to the human structure is your spine. Therefore, it makes sense that a lot of what you hear about the core is directly related to the spine specifically, and the torso in general. However, the core has another dynamic component that is involved with the specific control of your spine and your COG to keep you vertical and upright. These movements involve the deep intrinsic muscles of the spine including the mulifidus, erector spinae, the pelvic floor muscles, and the deep six hip external rotator muscles.
It is this aspect of controlling your spine and COG that muscles like the iliacus and psoas major, muscles we have already discussed in past articles, are so relevant when talking about the body’ core muscles. That is because these muscles are strategically located around your COG, a spot close to the top of and just forward of your sacrum. Along with these hip flexor muscles, the quadratus lumborum (QL) must be mentioned under the same breath. No pun intended!
Most think of the QL as just a simple quadrate muscle with straight up and down fibers passing from the iliac crest of the pelvic girdle and iliolumbar ligament to the bottom 12th rib, pausing to attach to the transverse processes of the lumbar spine. Its function, however, is more complex having three layers one of which runs in a vertical orientation as seen in most anatomy books.
The second layer passes down and in from the 12th rib to the transverse processes which ties the ribs to the lower back. Paired with the scalene muscles that again attach to the first and second ribs, this portion of the QL provides a suspensory type system for the entire rib cage or the “box.”
The third layer runs up and in from the iliac crest to the transverse processes. This configuration provides stability for the lumbar spine on the pelvis and along with the upper psoas at the very top of the leg initiates the human gait or walking movement.
This configuration of the QL just described while hard to physically see in an anatomy book, can cause the structural patterns like a lateral shift to the right or left of the rib cage and lateral flexion of the spine on the opposite side when walking which I often see when evaluating one’s gait.
All of these muscles just mentioned play a foundational role in support and stabilization of your spine and pelvis. In so doing, these muscles not only provide postural control and stability of your structure, but also transfer the power between your upper and lower limbs. But no one can deny the impact these same muscles have on your breathing.
Unfortunately, most people think of breathing and posture as two separate functions, but as you always hear me say, “everything is connected.” Boy, I can be so predictable! Good posture and breathing go together like peanut butter and jelly so good posture is vital for good breathing. Poor posture especially when sitting compresses your thoracic region and does not allow the diaphragm to open fully and freely.
Simply put, posture is the position your body assumes in relationship to your surrounding environment. Although posture is thought of as being static, it is actually a dynamic process with your muscles reacting to the forces of gravity and its effects in order to produce enough tension to keep you upright.
Because posture has such an impact on your breathing, I feel it is important for you to have an understanding of “good posture.” With each visit you make to my clinic, I evaluate your posture standing, sitting, and lying down looking for compensation of your structure in the horizontal plane, the plane that is parallel to the surface you sit on or the ground when standing.
I palpate and focus my attention on your pelvic and shoulder girdles, occiput, and mastoid processes to see if the right and left sides of your body are a mirror image as they should be when the body is at rest.
When the right and left sides feel different, equal loading or weight distribution to the forces of standing and sitting is no longer evident creating postural dysfunction. The dysfunction is due to the compensation by your neuromuscular system in order to keep you upright. It is what I refer to as your “compensated vertical” position with your COG being altered from the ideal position. Again, the ideal position of your COG at rest is located at about the second sacral segment equal distance between the front and back and right and left sides of your pelvic girdle. With this compensated vertical position, your movements and breathing will also become altered from the ideal and become dysfunctional.
Therefore, you need to be aware of your “true vertical” or “neutral position” while sitting or standing to allow your movements and breathing to become more efficient. Neutral posture is the position of your body that places the least amount of stress on your musculoskeletal system while allowing for maximum control and power. Maintaining a neutral posture is one of the fundamental principles of sound ergonomic design in the workplace and at home.
I will be showing you exercises to do in the clinic in order to establish this “neutral position” of your skeletal structure. I will also be showing you exercises to do in order to establish a normal breathing pattern. If I forget, please remind me.
Like most people, I used to think that only clients with a breathing dysfunction need to concentrate on their breathing. As you can see, that if far from the truth. Most of us have acquired a breathing dysfunction over time that needs to be addressed. Everyone needs some breathing instruction and especially those of you who visit my clinic for musculoskeletal issues. I look forward to working with you in altering your breathing patterns.
In closing, keep up the good work in corralling this virus. Even though I have received both of my injections for COVID-19, I will continue to wear a mask. I expect you to do the same until further notice. Thank you. Be well.
Terry