For the Love of All Things Good, Stop Sucking In

This blog was originally posted on and has be adapted by the author for this website.
Two weeks ago NPR posted an article on how to quickly fix “Mummy Tummy” (what they actually meant was diastasis recti) in 10 minutes a day.  There have been a lot of quick fixes for correcting and flattening diastasis recti going around the internet and this article even stated “You can easily expect to see 2 inches off your waist in three weeks of time”.  The article went as far as stating the exercise, which is abdominal hollowing, is backed by research and physicians. Two days later NPR released another article stated that yogis knew all about this method long before but stated “you want to make sure your pelvic floor is strengthened and recovered before doing Kapalbhati, Allen says. “Otherwise, it could make things worse.””

Now, two weeks later, NPR has released a third article stating “Unfortunately, there hasn’t been much research that looks at how effective any particular exercise is — or is not — in fixing diastasis recti.” and that the creator “thinks the “breath-in” exercise can strengthen abdominal muscles”.

To recap, NPR first stated that the exercise is backed by research, then stated it has been in practice a long time and to use caution because it can worsen pelvic floor control (ah-hem, urinary incontinence) and now they are saying that we need more research (there is no disputing that!) and the method they were promoting is only thought to be beneficial. The thing is, critical evaluation of current research does not support these methods and actually contradicts their use in treating diastasis recti and the pelvic floor and here is why:

Abdominal Hollowing

When breathing is discussed most people think of sucking or drawing in their stomach or pulling their belly button inward to support their body. This movement, called abdominal hollowing, became the gold standard in 1996 after Paul Hodges and Carol Richardson released an article in Spine stating “the delayed onset of contraction of transverse abdominis indicates a deficit of motor control and is hypothesized to result in inefficient muscular stabilization of the spine.” Abdominal hollowing became popular because it creates concentric contraction of the transverse abdominis and should theoretically help stabilize the spine. In reality, a study released in 2009 showed that all the muscles have a delayed contraction and not just the transverses abdominis in people with low back pain.

Research has since evolved and grown since 1996 but exercise practices have not kept up with the research in regards to core strength and stability. Concentric contractions, like those created by abdominal hollowing, create a force that is always less than the muscle’s maximum potential. Dr. Stuart McGill released a study in 2001 showing that activation of the transverse abdominis along does not improve spinal stability as it can inhibit activation of the external and internal obliques. An article published on August 25, 2017, found that the transverse abdominis is actually excessively active in patients with pregnancy-related posterior pelvic girdle pain. Therefore, even though a person is strengthening the transverse abdominis, abdominal hollowing focuses on strengthening the muscle to its suboptimal potential and can actually decrease core stabilization and increase pelvic girdle pain.

Abdominal hollowing also activates the abdominal wall without co-activation of the diaphragm. This causes the transverse abdominis to activate independently and does not create intra-abdominal pressure to help stabilize the spine. In fact, the biomechanics created when a person does abdominal hollowing causes instability throughout the spine and system. The act of hollowing will create an oblique position of the diaphragm and pelvic floor, increases lumbar lordosis and creates hyperactive spinal erectors and stresses the psoas. This is important in people who have chronic low back pain and “tight hip flexors”.

Furthermore, abdominal hollowing does not create a movement that is replicated in function…one would not suck in their belly prior to lifting a grand piano as this would create instability.

So what is important in “Core Stabilization”?

In 2012 Kolar released two articles in the Journal of Applied Physiology and the Journal of Orthopedic Sports Physical Therapy showing the importance of the diaphragm. He found that respiration and stability are inseparable as we cannot stabilize without proper breathing mechanics. “It is through respiration that continuous activation of the diaphragm, abdominal wall and pelvic floor are maintained”.

Intra-abdominal Pressure – is it really a bad thing?


The ideal Gas Law (PV=nRT) helps us understand that pressure and volume are inversely related and therefore must work in unison to create a stable environment. Volume is controlled by the contractile nature of the core because our bodies are able to expand and contract in relation to outside forces. As one inhales, the diaphragm moves downward in unison with the abdominal muscles and pelvic floor to eccentrically contract and regulate the volume of the abdominal cavity. By regulating the volume, the intra-abdominal pressure is also controlled.

During inspiration the abdominal wall expands to maintain volume (and pressure) if no additional stability is needed. However, when additional stabilization is needed, the abdominal wall maximizes its expansion causing a decrease in volume of the abdominal cavity thereby increasing intra-abdominal pressure to stabilize the system. It is a deep, stabilizing breath that allows the abdominal wall and pelvic floor to be fully activated, specifically the anterior, lateral and posterior aspects of the abdomen creating increased intra-abdominal pressure (see drawing above). This pressure is what creates proper and efficient stabilization of the spine.

Abdominal Bracing

The Functional Progressions, which are based off the research and work done by Dynamic Neuromuscular Stabilization, focus on creating intra-abdominal pressure through abdominal bracing. Abdominal bracing creates an eccentric contraction of the abdominal wall (including the transverse abdominis) while co-contracting the diaphragm and pelvic floor. The eccentric contraction is beneficial because it strengthens the muscle as it lengthens, which is when much of a muscles normal activity occurs. Therefore, the greatest muscle strengthening is gained  during the eccentric contraction which is why abdominal bracing is important.

Abdominal bracing helps maximize intra-abdominal pressure in a way that is natural to how humans function.  Bracing creates a neutral posture through joint centration that helps stabilize the spine for all movements. Without proper breathing mechanics a person cannot stabilize using proper patterns and compensatory movement patterns will be created resulting in instability. It is through joint centration and abdominal bracing that ideal movement patterns can be utilized that enhance performance while decreasing the risk of injury.

Abdominal Bracing & Pregnancy/Postpartum

It is common for postpartum women to have areas of concern such as incontinence or diastasis recti. These signs and symptoms are created when one can’t appropriately react to pressure or volume and indicate the need to maintain appropriate intra-abdominal pressure by integrating the breath (diaphragm) with the abdominal wall and pelvic floor. It is through intra-abdominal pressure that stability is created and the pelvic floor and abdominal muscles can heal.

Abdominal Bracing & The Athlete

Abdominal bracing is a huge component of proper lifting. As Dr. Richard Ulm stating, “In both training and sport, we must remember that movement is preceded by stabilization of the spine.” For more information on the importance of breathing in the athlete, please check out Dr. Ulm’s article in NSCA, STABILITY AND WEIGHTLIFTING—MECHANICS OF STABILIZATION—PART 1 .

If you are looking for more information in regards to athletes and the importance of intraabdominal breathing, check out Dr. Ulm’s information at Athlete Enhancement or his youtube site.


-Richard Ulm’s “Stability” course at National University of Health Sciences

-Bordoni, B, and Zanier, E. Anatomic connections of the diaphragm: Influence of respiration on the body system. Journal of Multidsciplinary Healthcare (6): 281-291, 2013.

-Hodges, PW, Eriksson, AE, Shirley, D, and Gandevia, SC. Intra-abdominal pressure increases stiffness of the lumbar spine. Journal of Biomechanics 38(9): 1873-1880, 2005.

-Hodges, PW, and Gandevia, SC. Changes in intra-abdominal pressure during postural activation of the human diaphragm. Journal of Applied Physiology 89(3): 967-976, 2000.

-Kolar, P, and Andelova, V. Clinical Rehabilitation. Prague: Rehabilitation Prague School, 2013. N. pag. Print.Dynamic MRI and synchronized spirometric assessment. Journal of Applied Physiology 109(4): 1064-1071, 2010.

-Kolar, P, Sulc, J, Kyncl, M, Sanda, J, Cakrt, O, Andel, R, et al. Postural function of the diaphragm in persons with and without chronic low back pain. Journal of Orthopedic and Sports Physical Therapy 42(4): 352-362, 2012.

Lauren Keller, DC, DABCA


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