What Is Rib Flare? - Core Exercise Solutions

This type of rib flare is a bit harder to address because it requires changing how muscles fire versus their position from front to back.

You have small muscles, called the internal intercostals, that run between your ribs. These muscles work with the abdominals to produce a forced exhale. I often find that women who have a larger rib cage infrasternal angle (wide ISA) postpartum are stuck in a state of inhalation. (Meaning, it always looks like they are sucking air in.)  When you don’t move a part of the body regularly, like your ribs or spine, it can get stiff and present with some difficulty moving out of that position. Pregnancy pushes the ribs up and out (into a state of inhalation) to make room for the baby, so it often takes a bit of manual pressure and coaxing through specific exhalation exercises to get those ribs back down and in.

Rib Cage Flare Out to Sides

A wide ISA, or rib cage flared out to the sides, prevents someone from getting a good inhale because they are stuck up in an already inhaled state. From a rehab perspective, I like to start with working the exhale and coaxing those ribs into movement. Your ISA (front angle of the rib cage) should change with each breath. On the inhale it should widen, and on the exhale it should narrow. Being stuck narrow or wide with limited movement for breathing is something you’ll want to address. 

What Causes Rib Flare on One Side?

If you find yourself looking in the mirror at one side of your rib cage and see it sticks up more or rests at a flatter angle, this is one-sided rib flare. Most people have some left rib flare due to the diaphragm attaching lower on the right side. It’s just easier for the body to keep that right rib tucked in. It’s fun to think about how we’re not even on the inside, so why should we expect to be naturally even on the outside? 

Unfortunately, one-sided rib flare can lead to neck and back tightness as well as a rotation in the pelvis. But there are exercises that can help get that flared side back in and responding well to breathing! 

Pelvic Floor Rib Flare

Pelvic floor tightness can promote a state of inhalation. Crazy, right, that a little tightness in the pelvic floor can actually decrease the amount the diaphragm expands down, leaving your diaphragm stuck up and ribs stuck out?

As the diaphragm contracts down on the inhale, it helps to stimulate our vagus nerve which is our “chill-out” center. It’s no wonder pelvic floor tightness can increase anxiety! The psoas (deep hip flexor muscle) that attaches into the back of the diaphragm has been coined the “emotional muscle,” probably for a similar reason. If you’re always in a shallow breathing pattern, usually spurred on by paradoxical breathing, then you never release the top of the psoas through great back (not belly) diaphragm expansion. Getting those ribs down and in and getting a great exhale can go a long way for both our physical and emotional states.

Diastasis Recti Rib Flare

I hope this helps explain the meaning of rib cage flare or rib cage angle and gives you a helpful point of reference for reflecting on your posture!

How to Fix Rib Flare

Rib Flare Test

Lie on your back and take a few deep breaths, letting your organs settle and abdominals relax. This will create a clearer rib cage picture. Then have someone snap a picture looking down at your ribs. You can take that picture and outline your infrasternal angle (the angle the ribs come together in the front). 

The optimal angle is 90 degrees. A wide ISA is greater than 110, and narrow is less than 90. One other thing to note is whether or not this angle changes as you breathe. Does it increase when you inhale and decrease when you exhale, or does it stay the same?