What is 'NORMAL'

"I've been told I have a 1 cm stomach separation"

We hear this concern all the time at the WIF clinic and thought we should explore this a little further.

Firstly lets recap what and where the linea alba is. The linea alba is a 3 dimensional flexible structure made up of collagen fibres - think of thick elastic band, oval in nature. It extends from the breast bone to the pubic bone and is the midline connection that brings the two sides of the rectus abdominis (the 6 pack muscle) together. The function of the linea alba is to support the abdominal muscles in position, and along with other connective tissue bands in the trunk, gives control to the whole abdominal wall. The other abdominal muscles, obliques and the transverse abdominis also have connections into the linea alba.

The linea alba has the ability to stretch and widen during periods of prolonged increased intra - abdominal pressure (e.g. pregnancy or obesity). This can lead to a widening of the 'inter-recti distance' (the distance between one rectus muscle and the other). If stretched the linea alba can show signs of doming, sinking or bulging along its length during functional exercises.

So… what is the 'normal' width of the linea alba?

Spoiler alert… it's not Zero!

A study was carried out on 150 women aged between 20 - 45 years of age who have never been pregnant to answer this question.

They found up to 2.2cm width at 3cm above the belly button, 1.6cm width at 2cm below the belly button and 1.5cm at the breast bone is normal width of the linea alba in this population.

Therefore there is A NORMAL PHYSIOLOGICAL DISTANCE between the two rectus muscles even prior to pregnancy.

It is extremely important for us to know what is within normal limits, to then know when intervention is required during pregnancy or in the postnatal period.

A 1-2cm distance is 'normal'. However, it is not always about the GAP. The function, thickness and depth of the linea alba is potentially more important than the width to assist with overall abdominal control and your ability to create tension in your tummy muscles.

If you are concerned or have been told you have a tummy separation, come and see the team at Women In Focus for a thorough assessment and correct guidance… Contact us today.


Reference: Beer, G. M., Schuster, A. , Seifert, B. , Manestar, M. , Mihic‐Probst, D. and Weber, S. A. (2009), The normal width of the linea alba in nulliparous women.Clin. Anat., 22: 706-711. doi:10.1002/ca.20836