New concepts in diastasis
We need a LOT more research to understand diastasis. For an overview of how the research informs our current understanding…check out my previous 2 blogs “The deal with diastasis” and “Diastasis doesn’t need to be disastrous” and the research publications that I have been involved in .
Before I delve down the rabbit hole I am peering into…I wish to reinforce that diastasis is about much more than just the gap. However, it is the gap that (i) currently alerts us to diastasis, (ii) defines it within research studies and (iii) the thing that women with diastasis are most concerned about. Therefore, I began to try and better understand what exactly we are measuring when we refer to the gap.
Traditionally, we have always considered the gap to be a thinning and widening of the linea alba, the thin connective tissue joining the right and left rectus abdominis muscles at the midline. This is a normal and expected feature of the human body so that it can accommodate changes in abdominal girth and shape (such as pregnancy, digestive or medically related bloating or excessive weight gain). Excessive widening is considered to be the reason behind diastasis meaning that the linea alba connective tissue is thought to stretch sideways beyond its elastic limit. However, researchers investigating the properties of the linea alba have reported that it is a rather inert structure, particularly in the transverse plain. This means that it is rather resistant to stretching sideways. It offers more elastic properties in the longitudinal direction, meaning that it can “give” or stretch with the changing abdomen during pregnancy, bloating, weight gain etc.
So if we understand that diastasis refers to a midline “gap” that creates distance between the rectus abdominis muscles, yet the linea alba connective tissue between the rectus muscles doesn’t tend to stretch sideways, then what are we measuring?
I propose that we are measuring some degree of linea alba thinning and widening, COUPLED WITH empty rectus sheaths as a result of rectus abdominis muscle wasting. The rectus sheaths are the connective tissue film (aponeurosis) that wrap around the muscle. We understand that many women experience rectus abdominis muscle wasting during pregnancy and even more so when they have diastasis. If we consider sausage meet wrapped within its film wrap, I am sure many of us can relate to seeing a sausage that has spare sausage wrap which isn’t filled with meat at either end? I propose that something similar may be happening in relation to the rectus abdominis in women with diastasis.
Check out my video offering a visual to this hypothesis:
This may explain why two women presenting with the same width of “gap” can respond to rehabilitation at different timescales to each other. One woman may see improvements in her diastasis within a matter of weeks while the other takes months and months to see small progressions. Could one lady be experiencing a quicker response from building muscle bulk in the rectus (hypertrophy) while the other woman didn’t have as much muscle wasting to begin with so is waiting for the longer-to-achieve connective tissue changes at the actual linea alba?
For health professionals who use ultrasound imaging you may be thinking that this would be a quick way to verify my hypothesis? However, ultrasound imaging is a greyscale image and just like the linea alba connective tissue, the rectus sheaths also appear as a bright white appearance (hyperechoic). Therefore even if women are experiencing wider inter-recti distance due to empty rectus sheath, it appears like an extension of the linea alba connective tissue on ultrasound imaging.
Why is this important to understand?
Many reading this may be thinking “who cares..it doesn’t change how we manage diastasis in our clients.”
I think it is important for us to better understand the pathophysiology of diastasis so that we can competently goal set and prescribe the appropriate rehabilitation. If this theory was to be supported by future research it could also mean that clinical triaging and differential diagnosis would enable more informed signposting to the best management plan. Those with significant muscle wasting in their rectus, and empty rectus sheath, will have more odds of responding to muscle bulking through loading and rehabilitation and therefore improve their diastasis, whereas those without muscle wasting may be more limited in their rehabilitation potential.
I would love to hear your thoughts on this? Have you considered something similar? Does it even matter?