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How your abdominal muscles work together

By now you probably know all about doming, bulging and sinking - if you don't check out this video HERE.

What you may not know though is why this happens and how when your abdominal muscle strength is balanced you can stop it from happening.

First lets check out the abdominal muscles in your core.

Core muscles

You core is much more than just your abs - it includes your pelvic floor, diaphragm, and back muscles as well.

But today the muscles we are interested in are:

  • Rectus Abdominis (RAs) aka 6 pack abs

  • External Obliques (EO)

  • Internal Obliques (IO)

  • Transverse abdominis (TVAs)

Notice how the transverse abdominis, internal obliques, and external obliques all tie the front to the back like a corset.

Now lets look and the front more closely

Notice the Linea Alba that is between the rectus abdominis muscles - this is what is stretched with diastasis recti.

Like this:

Also note how the Aponeurosis of the abdominal muscles cross over and connect with each other.

Because of this you can't contract one part of your abdominal muscles without pulling slightly in the rest.

So when you contract your TVAs at the beginning of the contraction you will get the TVAs then with a slightly stronger contraction the IOs will engage, then if you keep going the external obliques and finally if you really over engage the rectus abdominis will engage.

So when you are trying to engage the deep core muscles (TVAs and internal obliques) you want to keep the contraction small so you are strengthening them without the over-dominance of your external obliques and Rectus Abdominis.

Now lets look what happens with:


With diastasis recti often you will see doming when doing a crunch or any movement that puts pressure on your abdominal wall.

This happens when you aren't loading your core correctly.


Bulging happens when the rectus abdominis are working hard and the TVAs and internal obliques are not strong enough.

This can happen to anyone whose core is not balanced, and is often seen in movements like double leg lifts.

The rectus abdominis pulls everything upwards

Balance Core

In a balanced core the deep core (TVAs and IOs) pull the RA muscles down and out creating tension in the connective tissue.

This happens with and without diastasis and is the correct way for the abdominals to fire.

You will note that the muscles still rise a little due to the RAs working - but not as much as in the bulging.

I hope that this has helped explain how your abdominal muscles work together and why your deep core muscles are so important for creating tension in the connective tissue.

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