After pregnancy, many people notice their rib cage feels wider or more prominent. Maybe you’ve heard the term rib flare tossed around and started wondering:
“Is this something I need to fix?”

Let’s clear the air.
Your rib cage naturally expands during pregnancy to make room for your growing baby. That expansion doesn’t always go back to its pre-pregnancy state — and that’s not a problem. But if your ribs stay lifted or you’re having trouble coordinating your core, it’s worth looking a little deeper.

Not to “fix” your ribs.
But to support your system — your breath, your posture, and how your body handles pressure and load.

Let’s break down what rib flare is, why it shows up postpartum, and how you can rebuild the coordination your core actually needs.

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What Is Rib Flare?

Rib flare refers to when the lower ribs angle outward or lift away from the pelvis — usually due to a widened infrasternal angle (the angle between the bottom of your rib cage). While everyone has a natural rib angle, a more flared presentation can indicate a mismatch in pressure, breathing patterns, and muscular coordination.

In many postpartum cases, this wider angle is a result of:

• Rib cage expansion during pregnancy
• Changes in breathing mechanics
• Altered postural strategies to accommodate a growing belly

These changes are normal and adaptive during pregnancy, but they often linger postpartum — especially when combined with weakened obliques, pelvic floor shifts, or limited thoracic mobility.

How Rib Flare Affects Core Function

Your core isn’t just your abs — it’s your whole trunk system: diaphragm, obliques, pelvic floor, deep back muscles, and more. For that system to work well, the rib cage and pelvis need to coordinate together.

When your ribs are flared:

• Your diaphragm can’t descend as well — limiting your ability to generate intra-abdominal pressure.
• Your obliques and serratus (key core stabilizers) get underused.
• Your lats may take over, pulling your rib cage into more extension and further disrupting alignment.
• Your pelvis often compensates — either tucking under or flaring out, creating imbalance below.

That means you’re not just looking at a rib issue. You’re looking at a system that needs recalibration.

The Full-Body Contributors to Rib Flare

1. Limited Thoracic Mobility

The upper back (thoracic spine) is designed to rotate and extend — but when it becomes stiff or restricted, the rib cage can’t expand and move fluidly with breath or rotation.
To compensate, your ribs might flare upward just to make space.

What helps:
Targeted thoracic rotation and extension drills that integrate breath — so your ribs and spine start moving together again.

2. Overactive or Tight Lats

Your lats attach to the lower ribs and can literally pull them outward when they’re tight or overused. In many postpartum bodies, lats try to stabilize the core because deeper muscles (like the obliques or diaphragm) aren’t doing their job yet.

What helps:
Lengthening the lats with breath-integrated stretches, followed by re-engaging the obliques and serratus to take over core control.

3. Weak Glutes and Pelvic Control

Your pelvis sets the base for your rib cage. If your glutes are weak or you’re lacking frontal plane control (side-to-side stability), your pelvis can tip or shift — causing your ribs to follow.

What helps:
Glute strengthening in positions that require core engagement — like single leg hinges, split stance work, and offset loading.

4. Underactive Obliques + Serratus Anterior

These muscles help pull the ribs down and in, connecting rib cage to pelvis. If they’re not functioning well, your body often defaults to bracing with upper abs or overusing lats — reinforcing that flared posture.

What helps:
Rotation, reach, and breathing exercises that bring ribs down and around, not just in and tight.

So What Should You Do About It?

Start with movements that bring awareness, mobility, and strength throughout your system — not just crunches or core holds:

Short Lever Side Plank with Rotation

This variation trains the obliques and serratus while promoting controlled thoracic rotation. By shortening the lever, it becomes more accessible postpartum and allows better focus on rib positioning and breath. The reach element encourages ribs to glide down and around, supporting core control without bracing from the upper abs.

90/90 Dumbbell Thoracic Rotation

In the 90/90 seated position, your pelvis stays anchored while you open through the thoracic spine — improving rotation and restoring rib cage mobility. Adding a light dumbbell challenges the obliques to control the movement while encouraging full rib cage expansion and posterior breath.

TRX Lat Stretch with Rotation

This drill targets tight lats that often pull the ribs into extension. The added thoracic rotation element encourages full-body integration and releases tension through the upper back and side body. It sets the stage for more effective core engagement by clearing space for the ribs to move.

Supine Band Pullover

Combining overhead movement with resisted breath and a stacked rib-pelvis position, this pullover variation teaches your core to stay engaged while your arms move — a crucial skill for real-life lifting and reaching tasks. It’s also a gentle way to reintroduce length to tight lats while training the ribs to stay down and responsive.

Half Kneeling Inline Press

This unilateral press variation builds anti-rotation strength while reinforcing rib-pelvis stacking and serratus strength. It requires the obliques, glutes, and deep core to work together as you press, creating a dynamic coordination challenge that mimics functional movement patterns like pushing, carrying, or bracing during impact.

Hooklying Breathing with Kettlebell or Banded Reach

This foundational drill resets your breath mechanics, pairing a grounded position with a weighted reach to activate the serratus and bring the rib cage into better alignment. It’s a gentle, yet powerful way to build awareness of how your ribs move and restore a diaphragmatic breathing pattern postpartum.

Single Leg Wall-Supported Deadlift

This movement strengthens glutes and hamstrings while challenging lateral stability and rib-pelvis control. With wall support, you can focus more on alignment and breath without losing balance. It’s especially effective for connecting lower body loading with core activation — a key skill for lifting, walking, and running postpartum.

Single Leg Hip Thrust Isometric Hold

Holding the top of a hip thrust position on one leg forces the glutes, deep core, and adductors to work together for stability. It exposes compensations like rib thrusting or hip drop and gives you the chance to correct in real time. The isometric nature of the hold enhances control and endurance — both of which contribute to better pressure management across the system.

Why These Exercises Work

These movements aren’t about forcing your ribs down. They’re about retraining your system to move, breathe, and stabilize in sync again. That means:

• Expanding where you’re tight (like the upper back and lats)
• Strengthening what’s underactive (like the obliques and glutes)
• Coordinating breath and movement under load

When you train this way, rib flare becomes less of a “thing to fix” and more of a byproduct of a body learning to work together again.

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Final Thoughts:

Rib flare doesn’t mean your core is broken.
It means your body adapted during pregnancy — and now it’s asking for support to come back online.

Zoom out. Breathe better. Move smarter.