The Second Diaphragm: Did You Know Your Pelvic Floor Breathes With You

10 minutes ago

4 min read

When we talk about the pelvic floor, the advice often starts with “squeeze and lift.” But these muscles also need to relax, lengthen, and respond to movement.

It is a dynamic, complex, living bowl of muscles that remains in constant conversation with every single breath you take.

In physical therapy, we often refer to the pelvic floor as the pelvic diaphragm - the lower partner to your main respiratory diaphragm. Together, they form a pressure system that supports your core, improves posture, and keeps everyday movement feeling smooth and natural.

The Breath-Pelvic Connection: How the Pressure System Works

Your respiratory diaphragm and your pelvic diaphragm sit parallel to one another inside your torso. Together with your deep abdominal and back muscles, they form an automatic pressure system that adjusts as you breathe, laugh, cough, lift, and move.

Here is what happens during a normal breath cycle:

On the Inhale: As you breathe in, the diaphragm contracts and moves downward while your lower ribs expand. This creates a gentle downward movement of intra-abdominal pressure (you can notice the belly rise up) and the pelvic floor responds by gently lengthening and lowering downward to accommodate.
On the Exhale: As you breathe out, the diaphragm naturally rises back up toward your chest, the abdominal wall draws back inward, and the pelvic floor passively returns upward too.

We take roughly 20,000 breaths a day.

This rhythmic, small movement happens 20,000 times a day (!) without any conscious effort when the system is integrated.

anatomical illustration showing the respiratory diaphragm beneath the lungs and pelvic floor at the base of the pelvis, with arrows indicating downward movement during inhalation and upward movement during exhalation. — Your pelvic floor moves with your breath - gently lowering as you inhale and returning upward as you exhale

So why Pelvic floor and Breathing Is the Foundation of Pelvic Health

Because your pelvic floor is mechanically linked to your respiratory diaphragm and affected by its movements, how you breathe directly dictates how your pelvic floor moves.

Breathing isn't just about getting oxygen into the lungs; it is a full-body mechanical event. A functional 360-degree breath expands the ribs laterally, relaxes the abdomen, and allows the pelvic floor to lower softly. This system acts as an internal pump, promoting circulation, calming the nervous system, and preserving full muscle length in the pelvic bowl.

And What Happens When We Breathe Too Shallow?

Modern life (chronic stress, sitting at desks, tight clothing, and the habit of gripping our bellies in) - often leads to shallow chest breathing.

When we only breathe into your upper chest:

The Diaphragm Gets Stiff: the main breathing diaphragm stays high and barely descends, missing its full range of motion.
The Pelvic Floor Stays Frozen: Without the gentle downward push of the inhale, the pelvic floor stops receiving its natural dynamic stretch. Over time, it can become stiff, hypertonic (overly tight), or unresponsive.
Neck and Shoulders Overwork: Secondary breathing muscles in your neck and chest overwork to lift your ribcage, leading to upper body tension.
Nervous System Disconnection: Shallow breathing keeps the body in a subtle "fight-or-flight" state, signaling to the pelvic floor that it needs to hold on tightly for protection.

What Changes During Pregnancy and Postpartum?

Pregnancy brings profound changes to this dynamic system, and as your belly grows, several adaptations occur:

Shifted Mechanics: The growing baby changes the angle of your ribs and diaphragm, modifying how deep your breath can expand downward.
Tissue Lengthening: Hormonal shifts soften connective tissue, while the abdominal muscles stretch and adapt to accommodate the baby.
Altered Load & Pressure: The pelvic floor supports increasing weight over months, which can alter its resting baseline and automatic recoil timing.

Even after a C-section birth (with no vaginal passing thought the pelvic floor), the months of postural adaptation, altered breathing patterns, and abdominal wall recovery still directly affect pelvic floor mechanics.

Exploring comfortable breathing is a foundational step in postpartum recovery. It does not replace targeted strengthening or individualized rehabilitation when those are needed, but it re-establishes the dynamic coordination between your breath and your pelvic floor.

A Two-Minute Somatic Breathing Exploration

Try this as an opportunity to notice, rather than an exercise to get right.

Get Comfortable: Sit in a supportive chair with your feet resting flat on the floor.
Place Your Hands: Rest one hand around your lower side ribs and the other softly on your lower belly.
Breathe In Gently: Inhale through your nose, noticing whether your lower ribs expand sideways and back into your hand. Imagine the base of your pelvis softly widening, getting closer to the chair. Avoid deliberately pushing downward.
Let the Breath Out: Allow your breath to flow out effortlessly through soft lips. Notice your ribs and belly settling naturally without pulling your stomach in or forcing a squeeze.
Observe: Continue for a minute or two, keeping your breath easy. The pelvic movement may be subtle, and it is completely okay if you don’t feel it at first.

Note: If you notice pain, increased pelvic pressure, or dizziness, stop and return to your usual breathing.

Bring this curiosity into your daily life: notice if you hold your breath when standing up, picking up your baby, or concentrating. Simply noticing can help you find easier ways to move throughout your day.

When the Pressure System Breaks Down

Breathing isn't just about movement - it is about managing pressure.

When your respiratory diaphragm, pelvic floor, and abdominal wall stop communicating smoothly, the intra-abdominal pressure created when you breathe, lift, or cough must go somewhere. If it can't escape upward or distribute evenly, it pushes outward against the most vulnerable place.

Selected References & Scientific Reading

Park, H., & Han, D. (2015). The effect of the correlation between the contraction of the pelvic floor muscles and diaphragmatic motion during breathing. Journal of Physical Therapy Science, 27(7), 2113–2115.
Talasz, H., Kofler, M., Kalchschmid, E., Pretterklieber, M., & Lechleitner, M. (2010). Breathing with the pelvic floor? Correlation of diaphragmatic and pelvic floor movement during respiration. International Urogynecology Journal, 21(4), 475–481.
Bø, K., & Nygaard, I. E. (2020). Is physical activity good or bad for the pelvic floor? A systematic review. Sports Medicine, 50(3), 471–484.
Hodges, P. W., & Gandevia, S. C. (2000). Changes in intra-abdominal pressure during postural and respiratory activation of the human diaphragm. Journal of Applied Physiology, 89(3), 967–976.