“The diaphragm is the most important muscle we have. There is no if, and, or but about it.”

That’s a bold statement from Brian MacKenzie, author and founder of Shift (formally known as Power Speed Endurance) and the Health and Human Performance Foundation. Bold statements are often met with skepticism in health and wellness, which is why it’s noteworthy when thought leaders from different disciplines agree; the respiratory diaphragm may be the most underappreciated part of human anatomy.

This is something Dr. Belisa Vranich, clinical psychologist and author of Breathe: The Simple, Revolutionary 14-day Program to Improve Your Mental and Physical Health and Breathing for Warriors, sees every day. She works with patients to optimize their mental and physical health with proper breathing techniques at her private practice in New York City. “You ask any educated adult about it, and despite the fact that the diaphragm is this enormous, complicated, and important muscle, they don’t know what it looks like or exactly how it works,” says Dr. Vranich. “The pictures we’ve seen of it are so underwhelming, we don’t really have the impression of how big it is or where it’s positioned in the body. It’s not an auxiliary muscle at all. Our body falls apart without it.”

The diaphragm may be our muscle of respiration, but it’s more than breath. It has an impact on all of our major physiological systems; posture, circulation, immune function, digestion, emotional regulation— the list is long.

As Tune Up Fitness co-founder Jill Miller says, “The diaphragm is an avatar for your entire body.”

Once you learn about the many functions and facets of the respiratory diaphragm, it becomes clear that dysfunctional diaphragmatic breathing has a cascading effect on your physical, mental, and emotional health.

The Respiratory Diaphragm

The word diaphragm is derived from the ancient Greek word diáphragma, which means “partition.” The respiratory diaphragm is a dome-shaped muscle that sits in the middle of the trunk, between the chest and abdominal cavities. It has two hemispheres, the left hemidiaphragm and right hemidiaphragm, attaching to the lower six ribs and converging at the top in a central tendon. Each hemidiaphragm has a long tendinous structure, referred to as the right and left crura, that attach to the lumbar spine. During inhalation, the diaphragm contracts, descends, and flattens out, allowing the lungs to expand, fill with air, and deliver oxygen to the body on a cellular level. During exhalation, the diaphragm relaxes and ascends back to its resting dome shape, allowing the lungs to empty and expel carbon dioxide.

Says Dr. Vranich, “When we think of breathing, we think of these little cut-out images of the lungs, and the fact is the lungs don’t do anything on their own. They don’t move, they don’t inhale, they don’t exhale, it’s really the muscles around them that gets them to move. All of these pieces are depending on each other to do the right thing.”

Holly Clemens is a professor of Sports and Exercise Medicine at Cuyahoga Community College in Cleveland, Anatomy Trains teacher, and Yoga Tune Up® instructor. She likes to compare a healthy diaphragm to an umbrella that moves with ease. “As you inhale, you open the diaphragm like an umbrella, expanding the ribs to make more room for the lungs to take in oxygen. When you exhale, just as if you’re lowering the umbrella slowly and carefully, the diaphragm relaxes and recoils, and the carbon dioxide can be breathed out. If you open up the umbrella fast and hard or the mechanism is not working properly, it wears out. The same thing can happen to an inefficient diaphragm. If you load it up too quickly, and keep it in a locked position for a while, it can result in adhesions to the diaphragm from surrounding organs. It can’t operate efficiently and properly. This can impact the overall function and health of that important respiration organ.”

The diaphragm is innervated (stimulated) by the vagus nerve and the phrenic nerve. The phrenic nerve originates in the cervical spine and provides motor control of the diaphragm.1 One way to appreciate how breath is impacted by the phrenic nerve and the diaphragm is to think back to a time you had the “wind knocked out of you.” This is something many of us experience in sports (getting hit in the gut by a ball, for example) or a fall and can’t catch our breath. When this happens, the phrenic nerve has usually been shocked, and the diaphragm is briefly paralyzed.2 While it normally resolves very quickly, the brief moments of gasping for air are illustrative of the power of a functioning diaphragm. The other way the diaphragm makes itself known is through hiccups. Hiccups are involuntary spasms of the diaphragm, and that familiar sound you hear is the sound of your vocal chords snapping shut from the sudden force of air in your throat.

The respiratory diaphragm is also a crossroad for three other critical biological structures, with holes for the following:

  • The esophagus, connecting the throat to the stomach
  • The vena cava, carrying blood from the lower body to the heart
  • The aorta, carrying blood from the heart to the rest of the body

Through this lens, the diaphragm is not a partition— it’s a hub. “People look at the diaphragm and think it’s a divider between the thoracic and abdominal cavity,” says Professor Clemens. “I look at it as a unifier. It has this beautiful relationship between the upper and lower parts of the body.”

“People look at the diaphragm and think it’s a divider between the thoracic and abdominal cavity,” says Professor Clemens. “I look at it as a unifier. It has this beautiful relationship between the upper and lower parts of the body.”

Says Dr. Vranich, “I like to think of it as being right in the middle of everything. It’s right above your digestive system, so it massages your gut from the bottom down, and it affects your pelvic floor because it’s right below your gut. And then it affects your lungs, your heart rate, and your brain because it’s right underneath it all. Its effects ripple upward and downward.”

The systemic effects of the diaphragm are foundational to Jill Miller’s educational programming at Tune Up Fitness. “If I were to do a Venn diagram of the muscular structure of the body, I would say it’s organized around the diaphragm,” says Miller. Through fascial connections, the reach of the diaphragm extends from the base of the tongue, through the heart, spine, psoas, quadratus lumborum, and all the way down to the feet.3 “The diaphragm gives me a chance to teach about fascial interfaces,” Miller continues, “and how the little things affect the big things.”

Posture and the Diaphragm

The diaphragm’s impact on physiology depends on its mobility. A diaphragm with space to contract and relax at its full range contributes to homeostasis in the body by allowing the heart, lungs, gut, lymphatic, and circulatory systems to function optimally. A diaphragm that’s locked down thanks to poor posture or fascial restrictions can’t pump efficiently, and that slows down everything from blood flow to lymph to digestion.

Brian MacKenzie of SHIFT sees this all the time with his clients. “All mechanics and movement patterns center around how well I have access to the diaphragm. If my spine is not organized in order to utilize the diaphragm correctly, the diaphragm has to work harder because it’s out of position. I will compensate through my extremities to make up for that. We get caught in poor positions all the time, which inevitably leads to poor breathing patterns.”

Physical therapist James Anderson of the Postural Restoration Institute says simply, “there is a direct link between posture and breathing.”

“The body itself has a system of internal chambers that literally shape the body and determine the body’s form, its posture, and ability to function,” says Anderson. “At the heart of that postural system is the chest cavity where the lungs and diaphragm are. Below the chest cavity is the abdominal cavity, and then the pelvic cavity. And of course above the chest we have the cranial cavity. All of these internal cavities have a posture. And what the diaphragm and abdominals can do from the inside out to shape the internal chamber posture determines how you and I hold our body upright against gravity. In other words, we change posture from the inside out.”

Upper Crossed Syndrome

One way we’ve changed the internal posture of the chest cavity for the worse is our modern reliance on cell phones and computers. So much time spent looking at these devices with our heads forward leads to a phenomenon called Upper Crossed Syndrome, with chins out and shoulders rounded. “It constricts the diaphragm,” says Holly Clemens. “The abdomen gets pushed up and breathing becomes shallower. This is going to impact lung function. If you’re in the same posture all the time, you’re stagnant. The water’s not flowing, the synovial fluid’s not flowing, the motor neurons, the nerves, and the myofascia get locked in that way.”

James Anderson says respiratory dysfunction is rooted in this compromised mobility of the diaphragm. “A very important element of its function is to be able to assume the proper shape with the proper support around it. I would like the diaphragm to be able to make a full, complete transition from a proper dome shape, which is the relaxed state of the diaphragm, to a proper contracted state, which is the flattened state of the diaphragm, and then transition back to a full, relaxed dome. If it can make that transition between both of those postures, then the likelihood of optimal diaphragmatic respiratory function goes way up.”

Chiropractor and SOMA therapy instructor Jason Amstutz works with patients in a variety of ways— including the ELDOA method of postural exercises— to balance spaces in the body for better access to diaphragmatic breathing. “We work on changing the posture to balance out the tensions. Then you get a better functional diaphragm and you get more oxygen to your brain. Everybody feels better.”

So while everyone from your grandmother to your music teacher may have instructed you to “sit up straight!”, it turns out it’s more complicated than that. According to James Anderson, “Sometimes people are standing the way they are is because it’s how they’re best able to get air through their throat and lungs, all while holding their body upright against gravity without undue stress or strain on their chambers and system. And asking them to sit up straight to get what might look like ‘proper alignment’ from the outside can cause further compensation inside. So anytime someone tells you to hold a better posture, the question I would ask is ‘did it make your body feel better? Are you more relaxed and comfortable? Or did it make your body more tense and strained in your upper back, neck, and shoulders?’”

Physiology and the Diaphragm

This leads to another common consequence of a dysfunctional diaphragm— physical pain. “When the diaphragm isn’t working properly, it results in compensation patterns that only lead to more problems. Other muscles in the upper back and neck have to take over to expand the rib cage and help fill the lungs,” says Clemens. “And this can lead to chronic back and neck pain.”

In addition to posture and chronic pain, the diaphragm is important for the following reasons:


“If you’re breathing in an atypical way, for example with your shoulders, you’re off balance. There’s research that actually shows you’re less likely to have knee and ankle injuries if you’re breathing diaphragmatically.”- Dr. Belisa Vrasich


“The esophageal pathway is through the diaphragm, so it also functions as a digestive muscle, in a sense. And when people have acid reflux, they have a failure of the esophageal hiatus to stay in proper tension. The rhythmic movements of the diaphragm also assists food’s movement through the guts.”- Jill Miller


“The pumping motion of the diaphragm is the way your body gets lymph, adrenaline, and cortisol out of your system. Everybody does these harsh detoxes, which can be brutal and sadistic. But lymph and the detoxification of your body depends on your diaphragm working well.”- Dr. Belisa Vrasich


“Since the diaphragm surrounds the vena cava and aorta, it also acts as a cardiac synergist muscle. Not only does it stroke that vasculature and help move blood around, but it’s also a bed for your heart. The heart is sitting right on top of the diaphragm inside a fascial sack called the pericardium.”- Jill Miller

Emotional Regulation

“If you have digestive discord, if you have dysfunction with sleep, if you have mental anguish and anxiety and all of these physiological, mental, and emotional features that blend together to give a human being a really negative experience, you need the nervous system to turn that over. You need the nervous system to help all the other systems transition and be properly regulated. And the key to the nervous system doing that for all the other systems is respiration; the mechanical ventilatory process that we’re talking about.”- James Anderson, Postural Restoration Institute

Relaxation Response

The diaphragm is one of the primary keys to turn ‘on’ your ‘off’ switch by stimulating the parasympathetic features of the vagus nerve.”- Jill Miller

Just Breathe

T-shirts, coffee mugs, and Instagram posts abound with advice to “Just Breathe.” But is it that simple? What does it mean to just breathe?
Jill Miller organizes her Tune Up Fitness breath curriculum around three zones of respiration:

  • Zone One: Abdominal
  • Zone Two: Thoracic
  • Zone Three: Clavicular


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Zones of Respiration. A primer for breath control. __ You’re breathing in one of these 3 zones depending on your intrinsic and extrinsic stressors. __ 1) ABDOMINAL ZONE is the most calming zone to respire in. It’s dominated by the contraction and relaxation the respiratory diaphragm and the distensibility of it’s downstream fascial interfaces: If your transverse abdominals are always stiff (from chronic over-tensioning or scar tissue), or your digestive organs are bloated or dysfunctional, your diaphragm will have a difficult time moving south to generate an adequate vacuum to pull air into your lungs….if that’s the case, you’ll bypass the abdominal breath and transition to the Thoracic Zone. __ 2) THORACIC ZONE is the ideal place to breathe when you need to move heavy things. It’s dominated by the intercostals and diaphragm. It functions best when the intercostals can actually move your ribs to create an adequate vacuum to draw air into your lungs. Tension from back muscles, pectoral muscles and obliques (and many others) can be at odds with the full “bucket handle range” of the ribs, thus forcing the need for air to bypass this region and transition to the Clavicular Zone. __ 3) CLAVICULAR ZONE is your emergency respiratory system. It’s your High Stress Solution. It’s dominated by all of the soft tissues above you collar bones including the scalenes, sternocleidomastoid, upper trapezius and levator scapula. Your shoulders will involuntary be thrust upward as your body gasps to bring air into your upper lungs. Not a long term breath strategy and is commonly seen under deep stress, asthma, fear, anxiety and panic attacks. __ Wanna embody your breath and improve your discernment of how and when to use the force of breath within these zones? Join me for Breath & Core Tune Up tomorrow in my Livestream on @chooseunion @tuneupfitness Click link in bio to register. __ #Breath #fascia #respiration #diaphragm #yogatuneup #therollmodel #rollmodelmama #therollremodel #stress #asthma #anxiety #coregeousball #yogatuneupballs #singers #sing #breathcontrol #anatomy #embodyyourbody

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Dr. Vranich says our anthropological roots are in the fuller abdominal breathing. “There’s a difference when we look at primitive man. He would squat in a seated position more often, and as a consequence was more of a back breather. He had a bigger diaphragm, better lung capacity, and larger nostrils. So primitive man was a better breather.”

As we evolved, our lifestyle impacted our breath mechanics.

“Because of the way we stand and sit, we have a weaker diaphragm, smaller lung capacity, and more narrow nasal passages. Being seated without moving, and now having medium and small screens is affecting our breath,” says Vranich. “When your eyes are looking at something on a small screen and not moving, you’re concentrating in a predatory state. It’s similar to when animals are going after their prey; they take very small breaths and don’t move a lot. That’s what we’re doing in front of our computers and when we’re texting. The big movements and big breaths don’t happen.”

Even with our evolutionary history, Dr. Vranich says we still begin life as belly breathers, but that starts to change at about age 5 and a half years old. “We looked at 158 kids, and I thought there would be a difference in gender, but there wasn’t. And 5 1/2 was exactly the age where it changed from belly breathing. It’s when you go to school, when you start sitting, when you start becoming social. It’s also when you start taking tests, and you often start bracing your middle because of that stress.”

At the Postural Restoration Institute, James Anderson and his colleagues help people understand the importance of seeing the abdominals as equal partners in functional breathing. “A lot of people view abdominals as a core stability muscle, and then they view the lungs and diaphragm over on the other end of the spectrum as respiratory control muscles,” says Anderson. “The fact is, the abdominals are primarily designed to coordinate respiration. They’re responsible for reshaping the dome during exhalation, but they’re also responsible for controlling the flattening motion when the diaphragm contracts. In Eastern cultures they use the abs to move the ribs and diaphragm, and they have more core stability. In Western culture, we have mechanical dysfunction because we think about core stability as sit-ups and planks. I call it misuse of abdominals, and it’s prevalent across multiple disciplines; rehabilitation, performance, fitness. While we think that makes us stronger, it also makes us stiffer. We’re not sleeping better or moving better. We don’t have resilience, movement, variability, and function.”

How Do We Breathe Better?

It’s one thing to know what we should be doing to breathe better. It’s another to break old habits and create new patterns. To help people differentiate the muscles of respiration and identify where they are unconsciously gripping or using breath muscles inefficiently, Jill Miller created a self-guided exploration of the respiratory muscles through something she calls the diaphragm vacuum. In addition to exploring the anatomy of respiration, the diaphragm vacuum teaches us how to:

  • Increase breath threshold, which has a psychological carry-over into daily life by helping us remain calm when stress takes our breath away.
  • Quickly enter a parasympathetic state, the place of relaxation and restoration.
  • Feel the connection between the diaphragm and ribcage from the inside out.
  • Feel and map the myofascial connections between the diaphragm and the muscles it attaches to below the ribcage.

Strategies to Optimize Breath

Identify Stuck Spots

“Get in the best position you can get into, and start breathing slowly and controlled, all the way in, all the way out. See what you feel. Where do you find restrictions? Where do you feel soreness or pain? This is your indication of where you need work. Pain is there for a reason.” -Brian MacKenzie

Mobilize Tissue with Soft Tools

“Tune Up Fitness massage balls like the Coregeous and Alpha balls are phenomenal tools to help people identify their diaphragm kinesthetically. It helps with circulation, and promotes better sensory and motor output.” –Holly Clemens

Breathe through the Nose

“The most fundamental thing in understanding breath work is understanding the difference between nose breathing and mouth breathing. The nose almost tricks me into needing to use the diaphragm more because I don’t have this big wide hole to pull air in and offload the breath cycle out. So for the next four weeks, don’t open your mouth to breathe, no matter what you’re doing. Close your mouth to walk, run, lift weights, do yoga. Do it through all of these processes for the next four weeks because it’s a way to reorganize your physiology, and teach you what it’s like to draw a full breath in and out with your diaphragm.” -Brian MacKenzie

Focus on the Exhale

“Our culture thinks breathing is inhalation. The diaphragm’s drive when it becomes dysfunctional is to be inhalation driven, where it wants to contract all the time, contract too much, contract too early, contract too late. It becomes this annoying excessive tendency to over contract. And then you become hyperinflated. Your rib cage and lungs become overexpanded, and it prevents the diaphragm from assuming its full relaxed, dome posture on exhale. It can cause you to be anxious, short of breath, edgy. You can address some of that by focusing more on the exhale, and holding your breath at the end of that, to give your diaphragm a moment to adapt to the reality that it can be dome-shaped and supported again in its relaxed state.”- James Anderson

Develop a Breath Practice

“We need a breath practice to counteract how we spend all our time. The diaphragm is a muscle and if you want muscles to get stronger you have to work them to exhaustion. You have to work your breath muscles out separately.”- Dr. Belisa Vranich (Her book has targeted exercises you can do at home to strengthen muscles of respiration.)

Mix Up Your Movement Practice

“Don’t repeat the same thing all the time. People that live on a bike have their own set of problems. Yes, they have a great set of lungs, and a strong heart and legs, but they’ve created a rigid spine which doesn’t help them do a lot of other things. I’ve been good at lifting weights, but neglecting the fact that I need to stretch. Then I married a woman who’s a yogi and now I know why I wasn’t doing it. It’s a lot of work. It’s hard, but to really make a change, you’ve got to be doing a variety of things on a regular basis.”- Jason Amstutz

Make Your Breath Your Sixth Sense

“Cultivate an awareness of how your breath is intimately tied to everything you do. Befriend your breath as a barometer of your inner state; use it as a sixth sense and follow it like a curious breath scientist. Let your body be the lab and watch the natural actions of your breath as you encounter stress, joy, quiet, eroticism, and play. As you build that awareness, you’ll be more comfortable when you introduce breath exercises. Manipulate your breath with novel exercises that challenge its pace, as well as your physical body dynamics. This will expand your overall tolerance, and help you reap the rewards of opening your inner medicine chest.”- Jill Miller

Perhaps the most important thing to understand about the diaphragm is that its default design is to help all of the systems in your body function optimally, and you have the power yourself to engage it in a way that allows you to move and feel better.

“We’re missing the forest for the trees,” says Dr. Vranich. “We’re so busy scurrying around looking for some supplement or biohack that we’re not just looking at what’s right in our very own body. The diaphragm is smack in the middle of everything. It’s directly underneath your heart and lungs, and right above your gut, your second brain. So if that machine in the middle of our body isn’t doing what we want or taking care of us well, then it might be that we’ve excluded this terrifically important part of it, so it’s inhibited and not moving the way it’s designed. I tell folks ‘you’re taking all these vitamins and doing all these detoxes, but you’re not breathing right, which is foundational for everything else.’ This explanation may sound simple, but it really is the foundation of our health.”

For more on this topic, see Jill Miller’s new book Body by Breath.


The Diaphragm and its Four Cousins: The Other Diaphragms

Chiropractor and SOMA instructor Jason Amstutz defines a diaphragm as a series of fascial connections that are horizontal to the floor. While the respiratory diaphragm gets most of the attention, osteopathic medicine has identified four other diaphragms in the human body4:

  • Tentorium Cerebelli: Separates the cerebellum from the inferior portion of the occipital lobes
  • Floor of the Mouth: Muscular floor of the oral cavity that connects the right and left side of the mandible.
  • Thoracic Outlet: The sternal bone and joints between the first two ribs and clavicle
  • Pelvic Floor: The muscles and connective tissue underneath the pelvis, including the levator ani and coccygeus.


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1. Oliver KA, Ashurst JV. Anatomy, Thorax, Phrenic Nerves. [Updated 2018 Dec 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513325/
2. Myers, Thomas. Body³: A Therapist’s Anatomy Reader, p. 68
3. Bordoni B, Zanier E. Anatomic connections of the diaphragm: influence of respiration on the body system. J Multidiscip Healthc. 2013;6:281‐291. Published 2013 Jul 25. doi:10.2147/JMDH.S45443
4. Bordoni B (April 23, 2020) The Five Diaphragms in Osteopathic Manipulative Medicine: Myofascial Relationships, Part 1. Cureus 12(4): e7794. doi:10.7759/cureus.7794

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