Understanding the Diaphragm
by Brittany Witherell
Student Physical Therapist

The diaphragm is an important organ we use to breathe. Although breathing is the diaphragm’s primary function, did you know it has many more important functions? It also helps with postural control which helps us stand tall and balance. It also plays a vital role in the vascular and lymphatic systems, is greatly involved in gastroesophageal functions such as swallowing, vomiting, and contributing to the reflux barrier, and GI mobility.

How it works:
When the diaphragm contracts, the whole sheet of muscle moves downward as we inhale air in, expanding the lungs. As we breath out the diaphragm ascends and your ribcage moves downward.

The Three Musketeers:
Diaphragm muscle + intercostal muscles + abdominals = together these supply the best biomechanical support for breathing, but they all must work hand and hand!

Is the diaphragm just an inspiration muscle?
NO! It wears MANY hats!

1. Respiration
2. Enhancing postural control
3. Suppressing gastric reflux forces
4. Lowering GI mobility
5. Enhancing venous return

How does it enhance postural control?
The diaphragm provides stabilization for the lumbar spine. Since this is located at the center of gravity, the diaphragm has an effect on global balance and how a human maintains their position. When performing tasks, trunk bracing is needed to maintain all spinal segments in a biomechanical neutral position. This requires the dynamic coordination of muscles. Although the diaphragm does not move the trunk voluntarily, its contraction stabilizes the trunk allowing for proximal stability before distal mobility.

Breathing > Stabilization:
The diaphragm is capable of controlling many things, however; breathing is always its main priority. When there is an increased demand for one of the diaphragm’s functions, the primary focus places more energy on breathing. This is why you might see runners bent over holding themselves up after a big race. This position enables their diaphragm to function more efficiently.

Many research articles have been posted correlating diaphragm function to postural stability. The diaphragm helps stabilize our trunk, allowing for proximal stability before distal mobility! Some recent evidence also shines a light on impaired diaphragm excursion in patients with low back pain. In the article titled, “Postural function of the diaphragm of persons with and without chronic low back pain” by Kolar et al. dynamic MRI’s were taken to look at diaphragm activity in patients with and without back pain. Results found that patients with chronic low back pain experience smaller diaphragm movements and recruitment throughout postural limb activities,

Overall, the diaphragm is extremely important for not only breathing, but various other functions. It is important to keep a healthy diaphragm in order achieve optimal posture, GI mobility, venous return, and suppression of gastric reflux forces.