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What Exactly Is the Pelvic Floor and How Does It work?

So we covered prehab and how it can be beneficial to see a physical therapist before giving birth, but why exactly do you need to see a pelvic floor PT at all?

Let's start by reviewing how your pelvic floor works under non-pregnant conditions.

(For this blog post, we will be referring to a pelvis with a vagina and uterus).

(1) Bony Pelvis

(2) Bony Pelvis With Pelvic Floor Muscles Present

(1) The picture on the left is the Bony Pelvis. You have 3 main bones of your pelvis; the sacrum - the triangular bone in

the middle - and two ilium bones on either side of the sacrum. The ilium bones connect in the front of your pelvis at the pubic symphysis joint. Each ilium connects to the sacrum at the SI (sacroiliac) joint.

(2) The picture on the right includes the pelvic floor muscles. The muscles expand from each bone of the pelvis and connect in the middle to form a bowl or hammock-like structure around the three "tubes" within the pelvis - the urethra, vagina, and rectum.

The Pelvic Floor Muscles

The pelvic floor has several different jobs:

(1) Control your sphincters - This means the muscles have to hold pee and poop in when you don't want to pee and poop, but also let pee and poop out when you do want to!

(2) Sexual Functioning - The muscles control arousal, help lubricate our tissues, and allow us to achieve orgasm. They also help pump blood back out of the engorged tissues after orgasm.

(3) Lift your organs - The organs that lie in the pelvis are the bladder, uterus, and rectum. The pelvic floor quite literally has to provide the floor support underneath these organs.

(4) Pelvic Stability - The 3 bones of your pelvis are held together by ligaments and muscles. Other muscles on the outside of your pelvis also provide stability (the glutes, hip flexors, adductors, piriformis), but the internal stability of the pelvis comes from the pelvic floor.

The Trampoline & The Canister

Under normal conditions, your pelvic floor performs these jobs by acting like a trampoline.

The black mesh that you jump on is analogous to the pelvic floor muscles. The springs that attach the mesh to the ring can be analogous to your tendons. The ring is your bony pelvis. And the legs of the trampoline are your legs.

In optimal conditions, the mesh has good mobility to allow for some descent with jumping, but even better tensile strength for the rebound. If the mesh is too "loose", you won't bounce back at all and you'll instead just sink toward the ground. If the mesh is too "taut", you won't descend at all for the preparation of the jump. If the ring itself isn't structurally sound, the whole trampoline would be unstable. And if the legs of the trampoline were also unstable or placed on uneven ground, like a hill or cobblestone street, the whole operation could be compromised!

This is why, when you see a physical therapist, we will look at the mobility and strength of your pelvic floor muscles, the structural stability of your bony pelvis, and the strength and stability of your legs.

Moving upward, we'll also look at how you use your abdominal muscles, the strength and stability of your back muscles, and your breathing patterns.

We look at these things because of the canister. Above your "trampoline", your internal organs and spine are supported within a canister system, much like the shape of a soda can.

The canister is your CORE!

The cylindrical "walls" of the canister are your abdominal and back muscles. The top of the canister is your diaphragm (which lies at the bottom of your ribcage). And the bottom of the canister is your pelvic floor!

The diaphragm and pelvic floor work together when we are breathing. When you inhale, the diaphragm descends or moves down to draw air into your lungs. When you exhale, the diaphragm ascends or moves back upward to push air out of your lungs.

Your pelvic floor moves with your diaphragm as shown below:

Inhale = Down ; Exhale = Up

Putting it all together!

Anytime you exert yourself (i.e. getting out of the car, rolling over in bed, picking up a laundry basket, jumping, running, coughing, sneezing, etc.), there is a build up of pressure within your canister core system. That pressure usually moves downward toward your pelvic floor. The pelvic floor then has to act like a trampoline and bounce the pressure back.

As stated above, if the structure or mesh of the trampoline are at all compromised, the trampoline might have trouble meeting the downward pressure and instead the pressure might be end up pushing through the trampoline. This is essentially what happens with stress incontinence. The "stress" of the system is too great and the pelvic floor cannot contain the urine. It's important to remember though that this could be because of other impairments within the trampoline structure and not just the mesh itself!

The canister pressure system also helps stabilize your spine if you are reaching outside of your base of support.

If you are reaching forward, especially if you are lifting, your core must support the load on your spine. If the musculature within the core system are not able to properly support the spine, this could lead to back pain.

If the core muscles can't do their job due to weakness, then we find other ways to create stability. One way we do this is by holding our breath. Cue the large gruuunt that comes out of our mouths when picking up our babies. That grunt happens when you close the glottis of your throat and stop your breath. The breath hold then creates a pressure increase within the core system and the pressure can help maintain stability of the spine.

However, the increase in pressure with a breath hold through exertion can be extremely detrimental over time. As we reviewed above, your diaphragm and pelvic floor work together. If you stop your breath, your diaphragm doesn't move and thus, your pelvic floor doesn't move either. If the intra-abdominal pressure increase pushes down on the pelvic floor and there isn't any movement - that would be analogous to jumping on a trampoline with no mobility for the bounce. With repetitive downward pressure on an immobile pelvic floor, the pressure can become too great and essentially "break through", leading to things like stress incontinence and ultimately pelvic organ prolapse.

Really any impairments (instability, weakness) within the trampoline or canister system could cause incontinence or prolapse with enough repetitive strain.

What do we do about this?

One quick and easy way to prevent stress incontinence is to BREATHE! When you are exerting yourself or lifting outside the base of support, you need your pelvic floor to lift against the downward pressure. We achieve this by EXHALING through the exertion. This is easy to put into practice when are you exercising or lifting heavy objects, but we tend to have a harder time employing this technique with our activities of daily living.

Try blowing out as you lift your kids, as you roll over in bed, as you get out of the car, as you reach for a cup in your cabinet, etc.

If you are experiencing prolapse, painful sex, urinary frequency, constipation, pelvic pain, etc. - there might be issues within your core system or your trampoline system. Seeing a pelvic health physical therapist for an evaluation can help you understand how your canister and trampoline are working. You can find information online to help with some of this stuff, but at Pelvio, we believe nothing compares to getting a hands-on, individualized assessment of your biomechanics.

Now, if you are thinking like a physical therapist, you may have started to understand that the canister pressure system is extremely impaired during pregnancy. This is why it is so important to find out how your body is working before the changes occur.

Next up on the blog series - how your canister and trampoline function during pregnancy!


(1) Lee, D. (2010). The Pelvic Girdle; An Integration of Clinical Expertise and Research. Churchill Livingstone.

(2) Cozean, N. Cozean, J (Host). "The Pelvic Floor is a Trampoline, Not a Biceps." Pelvic PT Rising Podcast. 21 July 2022.

(3) Massery M. Multisystem clinical implications of impaired breathing mechanics and postural control. In: Frownfelter D, Dean E, eds. Cardiovascular and Pulmonary Physical Therapy: Evidence to Practice. 5 ed. St. Louis, MO: Elsevier-Mosby; 2012:633-653.

(4) Massery M. Breathing and Postural Control: It’s all about Pressure! The Gas Exchange. Vol Summer. Ottawa, Canada: Canadian Physiotherapy Association – Cardiorespiratory Division; 2016:6-9.

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