The Second Diaphragm
What Your Low Back, Stress Levels, and Digestion Have in Common
A Breath You Didn’t Know You Were Missing
You breathe up to 25,900 times a day without having to think about it. But, have you ever wondered if you're doing it well? And more importantly, could the way you're breathing be keeping your body stuck in a chronic stress loop?
Most of us think breathing is just about air going in and out of the lungs, or maybe we think about the chest and belly rising and falling, but not much else. The most important part to understand is that the way you breathe regulates your emotional state. If you want a pick me up of energy, you can hyperventilate for a few seconds to get a quick boost of energy, or alternatively take some slow and deep breaths to calm down. But shallow or dysfunctional breathing patterns can leave you wired, anxious, or restless, even when there's no real threat around.
One of the most overlooked parts in the breathing process is your pelvic floor, or what I’ll refer to as the second diaphragm. This group of muscles at the base of your spine works in tandem with your main breathing muscle to regulate the pressure in the body, creating a stable system at the center of everything you are and do. When the pressure in any system is off, the system either implodes or explodes, and your body is no different. In your body, that pressure dysregulation can show up as problems that seem completely unrelated to breathing: like low back pain, digestive issues, hip tightness, or even anxiety.
Two Diaphragms, One System
Think of your torso as a sealed soda can. The top of the can is your diaphragm, the bottom is your pelvic floor, and the sides are your deep abdominal and spinal muscles. When the can is sealed and pressurized, it's strong and stable, you can place weight on it, toss it around, and it stays intact. But if you dent the side or weaken the bottom, the can loses its integrity. The same goes for your core. If the pelvic floor or diaphragm isn’t functioning well, the whole pressure system becomes unstable.
Your primary diaphragm sits under your lungs, separating your chest from your abdominal cavity. Its job is to help you breathe by pulling downward on inhalation, which creates a vacuum for your lungs to fill with air.
Your pelvic floor is a sling of muscles at the bottom of your torso, stretching from your tailbone to your pubic bone. Its job is to support the organs above it, control urination and bowel movements, and stabilize the pelvis.
But here’s what many people don’t realize: these two structures are meant to move together.
On each inhale, the diaphragm contracts downward, increasing pressure in your abdominal cavity. The pelvic floor should respond by gently yielding, slightly expanding to make space for this pressure shift. Then, as you exhale, the diaphragm rises and the pelvic floor naturally recoils upward, almost like a trampoline returning to its original shape.
This coordinated rhythm helps stabilize your spine, manage core pressure, support your pelvic organs, and promote calm, full breathing. But its benefits extend even further. When the breath and pelvic floor are in sync, it signals safety to your nervous system. A regulated, expansive breath down to the pelvic floor activates the parasympathetic branch of your autonomic nervous system (the part responsible for rest, digestion, and repair). Over time, this pattern of calm breathing can shift your baseline from tension and vigilance to ease and presence, helping you feel more relaxed, grounded, and even joyful.
When the Pelvic Floor Doesn’t Yield
Now imagine what happens when that system gets jammed.
How would it get jammed? Sitting. When you spend long hours in a seated position, especially slouched or compressed, your pelvic floor becomes chronically shortened and inhibited. Over time, it forgets how to yield. Add in the downward pressure of poor posture, and it’s no surprise that the breath becomes shallow and the diaphragm loses its rhythm.
This also explains why trying to "fix" your breath while sitting can be an uphill battle. In that position, your pelvic floor is often trapped and unable to move freely, which limits how deeply and effectively you can breathe. To truly restore breath mechanics, the body needs the freedom to move, which means starting with getting out of the chair.
If your pelvic floor is tight, guarded, or uncoordinated, it doesn’t yield properly on inhale. That creates a kind of pressure trap in your body. Your body tries to breathe in, but the pressure has nowhere to go. It may shoot upward, creating neck, jaw, or shoulder tension. Or push outward into the belly, contributing to bloating. Or even strain downward, aggravating pelvic floor dysfunction. Regardless of the compensation, this restriction in your breathing results in shallow, stress-based breath patterns.
This creates a cycle: less breath creates more tension, which creates less movement, which deepens dysfunction and increases compensation. Over time, this becomes a chronic stress condition inside your body, and unfortunately one that you may not even realize you’re carrying.
Surprising Symptoms of a Breathing Imbalance
The worst part is that unless you’re super sensitive to your body, you might not feel this imbalance in your breath. But here’s a list of ways it can manifest that WILL get your attention.
Low Back Pain
When the diaphragm and pelvic floor aren’t working together, your core loses its natural pressure regulation. Your spine and surrounding muscles have to pick up the slack, which often shows up as tightness or fatigue in the lower back, especially when standing or walking. You might also notice that your workouts don’t leave you feeling stronger, just more sore or compressed.
Hip and Groin Tightness
If the pelvic floor is overactive, it can pull on the joints and tissues around the pelvis. This makes hip mobility difficult and may cause pinching sensations during squats or lunges, or groin discomfort from sitting too long. Your hips might feel like they just won’t loosen up, no matter how much you stretch.
Neck and Shoulder Tension
When your breath becomes shallow, your body starts using accessory muscles in the neck and chest to help. This can result in tightness in the upper traps, jaw clenching, TMJ pain, and even tension headaches. It’s a classic case of using the wrong muscles for the job.
Digestive Issues
The coordinated movement of the diaphragm and pelvic floor gently massages the abdominal organs and supports digestion. When that rhythm is disrupted, you might experience constipation, bloating, or a sluggish, heavy feeling in your gut. Things just feel stuck.
Anxiety and Mood Imbalances
Breathing is deeply connected to the nervous system. When breath becomes shallow and disconnected, it can keep your body stuck in a low-grade state of fight-or-flight. This may lead to feeling on edge, having trouble relaxing or sleeping, or feeling emotionally reactive.
Pelvic Health Symptoms
The pelvic floor’s direct roles (controlling urination, bowel movements, and sexual response) are often the most noticeable signs of dysfunction. You might notice urine leaking when you laugh or jump, pain or discomfort during sex, or frequent urges to go to the bathroom.
Even if only one or two of these symptoms resonate with you, it may be a sign that your breath and core system aren’t functioning as well as they could.
How to Start Reconnecting the Diaphragms
The good news is you can start improving this connection right now, without equipment or advanced techniques. Just investing a little time and a little awareness will go a long way.
Keep in mind that muscle memory plays a big role here. If your body has been stuck in shallow breathing or pelvic floor guarding for years, it won’t change overnight. These patterns are deeply embedded in your nervous system and muscle recruitment strategies. That’s why consistency is key. If you’re looking for an amount of time this will take, I want you to remember two things. One, breathing correctly even for a few minutes can calm the nervous system down dramatically. Two, we’re looking for about 3500 repetitions to re-learn any movement pattern, even breathing. The more often you can practice, the better!
A great place to begin is with supine 90-90 breathing. Lie on your back with your legs on a couch or bench so your knees and hips are at 90 degrees. Place one hand on your belly and one on your chest. As you inhale through your nose, let your belly rise and imagine that your pelvic floor is gently softening or widening. As you exhale through your mouth, feel your ribs drop and your pelvic floor lift slightly.
Practice for a minute or two. Try not to force anything, just observe the rhythm and the amount of work it takes to send the air down. With time, your body will start to remember this coordination, and it gets easier to just let go. But if you find this hard at first, just remember that the goal is to return to your natural breath, not to perfect it.
Conclusion: Rethinking the Core Starts with the Breath
Your breath is more than just air. It’s a dynamic pressure system that supports movement, posture, mood, and health. And at the foundation of that system is your pelvic floor.
When your two diaphragms move in sync, you create strength without tension, mobility without collapse, and calm without trying. It’s not just about breathing better, it’s about moving, living, and feeling better.
So if your back is tight, your core feels off, or your nervous system feels fried, don’t just chase the symptoms. Start with the breath. Start with your second diaphragm.
If you liked this, check out my course at Four Lights Wellness, where I cover both physical and mental aspects of wellness: Healing (e)Motions: Trauma Release Exercises for People with Stress offers targeted physiological exercises aimed at reducing stress and mental health dysfunctions that can contribute to physical pain.