What is IAP?

Key Differences between IAP regulation, Valsalva, and Bearing Down

One thing active pregnant mamas constantly hear is to be careful not to increase intra-abdominal pressure (IAP) because it will cause a diastasis or pelvic floor disorders. This is most common in the mamas who lift and exercise during pregnancy. While the people who say this are all well-meaning and trying to be helpful, they often don’t realize the only way to not increase IAP is to stop breathing and that’s not beneficial to anyone! But before you decide to stop breathing to prevent an increase in IAP, let’s discuss the differences between straining (what people think of when they hear IAP), Valsalva, and true IAP.


Intra-abdominal Pressure

IAP is the pressure within the abdominal cavity that naturally increases every time you breathe. This is accomplished through proper diaphragmatic breathing. Proper diaphragmatic breathing naturally utilizes the diaphragm, lower rib expansion, and even the pelvic floor for both breathing and stabilization! As you breathe in your diaphragm expands downward and slightly outward while the pelvic floor GENTLY relaxes down to mimic the movement of the diaphragm. This movement naturally draws air into the diaphragm and increases IAP every single time you inhale to help stabilize the low back and pelvic floor. As you breathe out, the diaphragm moves upward and the pelvic floor gently lifts and tightens to support the pelvic floor and surrounding muscles. We want to breathe, stabilize, and be able to move all at same time to ensure we are not accidentally bearing down by holding our breath. This is one reason we never recommend someone hold their breath during movements as that more closely mimics bearing down.


Straining / Bearing Down during Pregnancy

Think of a time that you were really constipated and just wanted to go to the bathroom. That forceful pushing and straining or “bearing down” you did in order to achieve a bowel movement is abdominal straining. During straining the pelvic floor eccentrically contracts and relaxes to help improve voiding (1). While bearing down can be beneficial in the case of constipation (but still not advised; if you have chronic constipation please reach out to a local functional medicine doctor to help you get better bowel movements), it is not ideal as we move through our daily life. Constantly bearing down/forcefully pushing or bulging the pelvic floor musculature can actually lead to pelvic organ prolapse.


Valsalva during Pregnancy

The Valsalva Maneuver is also when one bears down but in this case the pelvic floor muscle response is to contract and lift the pelvic floor to stop the flow of urine. A few studies have shown that the Valsalva can help with pelvic organ prolapse by reducing the amount the pelvic floor drops, but this should only be completed with a trained women’s health physical therapist because if done incorrectly, it may lead to a bearing down movement instead (2,3).


IAP Regulation and Pregnancy

IAP regulation should be automatic, relaxed, and natural and should focus on generating optimal IAP. IAP regulation includes the gentle expansion of the lower ribs, activation of abdominal and back musculature as well as the pelvic floor without bearing down. This is easier said than done though because it can take some time (and practice!) to retrain our breathing depending on the causes of altered breathing. And yes it might take a little patience to get your breathing out of your chest into your entire abdominal cavity! Once we are able to regulate IAP without thinking about it, this becomes one of the best ways to activate the deep core muscles for better control and stability.


Benefits of Intra-abdominal Pressure and Pregnancy

BIRTHFIT movements are largely based on information from Dynamic Neuromuscular Stabilization which is one of the leading researchers in understanding the effects of breathing and how to properly regulate the natural changes that occur to create stability. As Pavel Kolar stated, “Core stability is not achieved purely by strength of abdominals, spinal erectors, glutes or any other muscles, rather core stabilization is accomplished through precise coordination of these muscles to generate intra-abdominal pressure.“ Through the creation of IAP, research shows that IAP regulation can lead to the following benefits:

  • An increase in IAP stabilizes the spine (goodbye low back pain)
  • IAP “can unload the spine during static and dynamic lifting tasks” (hello better support while lifting or living)
  • Provides anterior lumbopelvic postural stability (goodbye hip and pelvic pain)
  • Creates balanced co-activation of diaphragm and pelvic floor (hello pelvic floor health)
  • Activates the deep core muscles to allow for optimal coordination of improve joint stability

So the next time you second guess lifting or exercising for fear of increasing IAP, remember that IAP is actually supportive! But you might want to double check to make sure you aren’t bearing down while doing that lift…nobody wants to clean that mess.


Lauren Keller, DC, DABCA




  1. https://www.researchgate.net/publication/51038641_Misconception_of_the_Valsalva_maneuver
  2. https://obgyn.onlinelibrary.wiley.com/doi/full/10.1002/uog.4082
  3. https://www.ncbi.nlm.nih.gov/pubmed/22771226
  4. http://www.rehabps.cz/data/DNS_IJSPT_paper.pdf
  5. Nachemson AL, Andersson GBJ, Schultz AB Valsalva maneuver biomechanics Effects on lumbar trunk loads of elevated intraabdominal pressures. Spine. 1986;11:476–479
  6. Hodges PW, Gandevia SC. Changes in intra- abdominal pressure during postural and respiratory activation of the human diaphragm. J Appl Physiol2000;89(3):967–976
  7. Hodges PW, Eriksson AE, Shirley D, et al. Intra- abdominal pressure increases stiffness of the lumbar spine. J Biomech. 2005;38(9):1873-80
  8. Gardner-Morse MG, Stokes IAF. The effects of abdominal muscle co-activation on lumbar spinestability. Spine. 1998;23(1):86–92
  9. Gandevia SC, Butler JE, Hodges PW, et al. Balancing acts: respiratory sensations, motor control and human posture. Clin Exp Pharmacol Physiol.2002;29(1-2):118-21
  10. McGill SM, Grenier S, Kavcic N, Cholewicki J. Coordination of muscle activity to assure stability of the lumbar spine. J Electromyogr Kinesiol.2003;13(4):353-359


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