There’s a lot to consider when trying to define diastasis recti. Let’s start with the most basic and move to the more complex.
From an anatomical perspective
When humans develop in utero, most body parts occur in pairs—two arms, two legs, two eyes. The same is true of the abdominal muscles. There are four layers of abdominals—rectus abdominis, external obliques, internal obliques, and transverse abdominis. And likewise, each layer has a left and right side.
Rectus abdominis is the only abdominal muscle that runs vertically, and it is the one most people think of as ‘the 6-pack.’ The linea alba is the white connective tissue dividing the left and right sides of this muscle, and it is the structure that stretches when a diastasis occurs. Consequently, one of the most common definitions for diastasis recti is a space of greater than 2 cm (or 2 fingers’ width) between the inner border of the left and right rectus abdominis muscles.
From a functional perspective
Although the most common definition measures a diastasis recti by its width, it’s actually the depth that’s more important. This is because the depth indicates difficulty creating tension between the left and right sides, and without tension, there’s a lack of stability. To be fair, it’s harder to generate tension the farther apart these muscles get, but to discuss a diastasis in terms of the gap puts the focus in the wrong place.
To understand how to create appropriate tension in the linea alba, we have to return to the other three layers of abdominal muscles. The external obliques, internal obliques, and transverse abdominis, all wrap around to the front of the body. They create a sheath that encases the rectus abominis and joins the left and right sides at the linea alba.
For proper tension in the linea alba, these three layers must function correctly and pull outward. Although this makes diastasis recti sound like an abdominal issue, many parts of the body can impact these six muscles. This is why it’s actually a whole body issue and also why it can be so challenging to resolve. Not only do the abs have to function correctly, but so do all of the muscles that impact them. Further, back pain, pelvic floor dysfunction, or hernias can be associated with diastasis recti. They’re not caused by the separation, but the imbalances that prevent the separation from closing also contribute to these issues.
What is diastasis recti in pregnant women?
This 2014 study measured the space between the left and right rectus muscles in 84 first-time moms. They used ultrasound to determine that 100% of these women had a diastasis recti at 35 weeks pregnant. But they measured the gap, not the depth. What does this tell us?
Obviously, we need more research, but this may indicate that a diastasis recti is a normal adaptation when one grows a human in her uterus. Just as a vaginal birth is impossible without effacement and dilation of the cervix, carrying a baby to term may require a separation of the abdominal muscles. After all, that baby needs a space to grow into. Up, down, and backward are just lesser options when compared to forward.
We know the abdominal muscles have to stretch and elongate to grow a baby. In a similar vein, it stands to reason that the soft tissue between these muscles would also stretch. But what does that mean for the women diagnosed with diastasis recti after their babies are born? Let’s take a look.
What is diastasis recti in postpartum women?
During pregnancy, there are so many changes and physical limitations that many women aren’t even aware of a difference in the space between their abdominal muscles. But after birth, some women attempt to return to activities, and at this point, they notice abnormalities. For example, they may have a belly that sticks out more than expected. Or they may still look pregnant months or years after delivery. Further, they may notice a ridge or breadloaf-like shape down the center of their abdomen, particularly with sitting up from lying down. You can find a complete list of diastasis recti symptoms here.
This study in 2016 gave the rates of occurrence of diastasis recti as 60%, 45%, and 33% at 6 weeks postpartum, 6 months postpartum, and 12 months postpartum, repectively. But again, they measured the width, not the depth. This may tell us that a diastasis is a normal occurrence, which resolves for most women by 6 weeks postpartum. It may indicate that a diastasis recti that hasn’t resolved by 6 months postpartum is more likely to need some assistance. But by studying only the width, what are we missing?
Let’s briefly touch on diastasis recti in populations other than women before I return to this question.
Does diastasis recti occur in children or men?
The short answer is yes. In children, diastasis recti can actually be a normal part of development. As previously mentioned, every human starts out in utero, developing a left and right side. Sometimes, especially in babies that are born pre-term, the space between the abdominals hasn’t fully closed. Often, it doesn’t close until later in childhood as the individual develops better core strength and control.
Consequently, it should not be viewed as a problem in a child unless it results in an umbilicial hernia (i.e., the intestines coming through the belly button) or in limitations in function due to weakness or pain.
Unlike children or pregnant women, diastasis recti is not a normal part of any life occurrence for a grown man. However, it can still occur, and most information seems to link it to poor strategies used with exercise or lifting.
But, back to the postpartum woman
So, if a child can close a diastasis by developing core strength and a man can create a diastasis recti by using poor exercise techniques, it certainly stands to reason that there is a mechanical nature to this disorder.
Let’s consider the following scenario. A woman grows a baby in her uterus, and during this time, her abs and her linea alba stretch to create space for the growing baby. Her body allows for a diastasis recti (or separation) as a compensation for the necessary stretching. Now, let’s say that this woman has excellent movement strategies and good techniques for lifting and exercise. She gives her body time to heal, and perhaps, she’s in the population whose diastasis closes in her first 6 weeks postpartum.
Then, let’s consider a different woman. She also grows a baby and endures the abdominal stretching that creates a diastasis. But for this woman, let’s say she has postural faults or compensations due to previous injury, lifestyle, or weakness. Will she be able to create the tension through her abs and linea alba to close her diastasis after the birth of her baby? And what happens if this woman is not a first time mother, but perhaps has altered mechanics layered on top of altered mechanics due to carrying her second, third, fourth, or maybe even fifth child?
What does this mean for defining diastasis recti?
Well, obviously, there’s more research needed to help us answer these questions. But the current treatment for diastasis recti emphasizes a whole body approach. In fact, all three major issues after pregnancy—diastasis recti, incontinence, and prolapse—seem to result from altered coordination of the body’s deepest stabilizing system. The differences between these diagnoses may be due to differences in how the deepest part of the core functions in each woman and how it relates to other parts of the body.
This perspective also helps us to understand why all of the following can occur:
- a flat belly and a diastasis
- a protruding belly and no diastasis
- a protruding belly and a diastasis
- diastasis accompanied by incontinence
- diastasis without incontinence.
Just as differences among postpartum women can result in either diastasis recti, incontinence, or prolapse, so can similar differences cause varieties to occur within the category of diastasis recti. And this explains why treatment is so variably successful. What works for one woman might not work for the next because the treatment needs to be tailored to the woman.
If your diastasis is an effect of your altered breathing and postural changes after having four children, you will consequently need a different approach than your neighbor down the street who is a first-time mother, but who had altered mechanics prior to pregnancy due to a old ACL injury.
Hopefully, this has cleared up some of the confusion in exactly what a diastasis recti is and what it means for you. You may also want to learn how to do a self-test or to understand the causes behind this diagnosis.