In this short article I will be looking at the function and importance of the diaphragm, how it affects health, and what we can do to make it work optimally.
Yoga literature is full of descriptions about the power of the breath, and its connection to health, vitality and energy. We hear a lot about Prana, but very little about what we can actually do to harness the breath for everyday good health. It is not an exaggeration to say that a nation’s health depends on proper breathing, and yet this simple fact is generally ignored throughout the Health Sector.
The main muscle of respiration is the diaphragm, a large sheet of muscle dividing the thoracic and abdominal cavities. The lungs and heart sit above the diaphragm, and the other internal organs including the intestines, liver and spleen, sit below it. The fact that this muscle effectively seals off the two cavities has important consequences. We will look at these in more detail in Part 2 next month.
Functions of the Diaphragm
Firstly and obviously the diaphragm produces inhalation and exhalation. As the diaphragm descends air is drawn into the lungs, and as it ascends air is pushed out the lungs. The length and depth of breathing is dependent on how much the diaphragm moves between a full inhalation and a full exhalation. In an average healthy adult this is between 3 to 5 centimetres, and in a well-conditioned adult it increases to as much as 8 centimetres.
Massage of Internal Organs
The movement of the diaphragm also pushes and pulls the internal organs, effectively giving them a deep massage. As it descends it pulls on the pericardium surrounding the heart, and squeezes the organs in the abdominal cavity. On its ascent, it pulls these organs in the opposite direction while exerting pressure on the heart. This constant massage increases blood supply and waste removal and helps maintain organs in optimal condition.
The diaphragm is connected to the lumbar spine by the left and right crus tendons. In a fascinating interplay, a balancing act occurs between upward tension exerted by the diaphragm, and downward force exerted by the psoas major. An optimal balance of this mechanism contributes to efficient co-contraction of the small segmental stabilizers and large abdominal musculature. This helps provide a strong stable abdominal cavity. Failure to achieve this results in inadequate motion of individual lumbar vertebrae, and compensatory movement patterns.
The heart pumps blood through a network of arteries, arterioles and capillaries to supply oxygen and nutrients to every cell in our body. Blood is then returned to the heart through a system of veins. Blood is emptied from the veins into a large vein known as the Vena Cava, which runs from the lower abdomen to the right atrium of the heart. During inspiration, the descending diaphragm compresses the abdominal organs producing a positive intra-abdominal pressure. The pressure in the thoracic cavity is negative, creating a pressure gradient between the lower and upper parts of the vena cava. This pulls blood towards the right atrium and plays a key role in venous return.
In other words, the diaphragm operates like a pump bringing blood back to the heart. When the diaphragm pumps stronger, the venous return increases. And increased venous return increases the hearts cardio-vascular efficiency. An optimally functioning diaphragm is directly linked to good cardio-vascular function.
An Everyday Scenario
The first thing to remember is that the diaphragm is a skeletal muscle and so is under conscious control. And like all skeletal muscle it requires exercise to stay healthy, flexible and strong. Unfortunately today’s lifestyle often prevents the diaphragm being engaged the way it was designed. Imagine a typical scenario of someone driving to work. Car seats are often designed to lift the knees higher than the pelvis, causing the back to round and the abdomen to be compressed. The diaphragm is restricted, and the breath is shallow. The drive to work is followed by hours of sitting at a desk, again in a hunched attitude. Then the drive back home is followed by several more hours sitting on a soft sofa. In all this time, the diaphragm is prevented from moving through its intended range, and becomes weakened from simple lack of exercise. People then complain of back pain, poor digestion, food intolerances, tiredness, poor circulation and a host of other symptoms related to poor diaphragm function.
How Yoga Helps
There are simple exercises which are suitable for all levels of student, and the results can be impressive, with alleviation of back pain, improved posture and fuller breathing within weeks of regular practice.
Lying on the back, bring awareness to the diaphragm by breathing ‘down’ into the belly. The descending diaphragm is pushing on the internal organs, causing the belly to rise. Link the rising belly to the depth of inhalation. Once this connection is established, add a weight (start with something like a bag of potatoes) and attempt to lift the weight through the same distance as previously. Also pay attention to the exhalation, making sure it is complete. As the diaphragm strengthens, more weight can be added.
Lying on the front, breathe into the belly against the weight of the body. Feel the rise and fall of the body with the breath, enjoying the sensation of full and complete inhales and exhales.
This is a great way to strengthen both the back muscles and the diaphragm. Clasp hands on the back and lift the head and chest off the floor using the inhalation to lift and relaxing slightly down on the exhalation. Make sure the feet stay on the floor. As the diaphragm descends against resistance there will be a distinct lifting of the torso against gravity as the diaphragm supports the muscles of the lumbar spine. This exercise can be intensified by varying the arm position; from mild with hands on the back to strong with the arms stretched out in front. Repeat as often as desired, always working to synchronize the breath to the movement.
Intensifying the Practice
For more advanced students classical Hatha Yoga offers incredible techniques. Although these are described in the language of Tantra, they have physiological effects Yogis were clearly very familiar with.
‘Of all the bandhas, Uddiyana is the best. Once it is mastered, liberation occurs spontaneously’
Hatha Yoga Pradipika 3:60
Such praise for a practice serves to emphasize its astounding effects, and although these are similar to previously described, they are considerably magnified. In the practice of Uddiyana Bandha the diaphragm is stretched as in no other exercise.
With the lungs empty and a false inhalation with a closed glottis, a partial vacuum is created in the thoracic cavity, while the abdominal cavity remains at a higher pressure. This pulls the diaphragm strongly upwards, squeezing the heart, and producing a suction effect on the blood returning to the heart. The internal organs are given an intense massage, increasing the tone of the entire intestinal tract.
You can hang out in this posture with all its positive effects and now you can turn it into a fantastic diaphragm strengthener. All you need do is breathe very deeply. As you inhale you have to lift the diaphragm against gravity and that is a lot of extra work. Because the exhalation is assisted by gravity, you can really take it to its limit. The result is full strong breathing combined with all the cardio-vascular advantages of inversions. A beautifully simple way of achieving the ultimate workout!