By Irene Hernandez, PT, DPT, RYT
Diastasis Recti Abdominis (DRA) is defined as the separation of the two muscle bellies of the rectus abdominis. This is common during and after pregnancy and has been associated to lumbopelvic instability and pelvic floor muscle weakness. DRA occurs due to hormonal changes of the connective tissue, mechanical stress on the abdominal wall by the growing fetus, and displacement of the abdominal organs.
To date, there is a scarcity of studies on DRA’s prevalence, risk factors, consequences, or interventions aimed at preventing or reducing it. This is in marked change contrast with the plethora of opinions on social media, about how to regain a “flat tummy”, the different exercise programs touted by therapists and fitness professionals, as well as binders and compression garments.
In this blog we will review some bio-mechanical considerations regarding trunk stability and DRA, as well as the conclusions of a few of the most recent studies.
DRA and Trunk Stability
The abdominal canister is a functional and anatomical structure that contains the abdominal and pelvic viscera. It provides thoracolumbar vertebral stability for movement, visceral support and respiration. These functions depend on the interrelation of several myofascial components that bind the structure (1):
- The diaphragm, which, through the crura connects with psoas and the fascia of the pelvic floor and obturator internus muscle
- The linea alba, a complex connective tissue structure which connects the left and right abdominal muscles
- The deep abdominal wall including transversus abdominis (TrA) and its anterior and posterior fascial connections
- The deep fibers of the multifidus
The linea alba is affected by the expansion of the abdomen during pregnancy. Its width is known as the inter-recti distance (IRD). The widening and thinning of the linea alba has the potential to disrupt the biomechanics of the abdominal canister, affecting abdominal muscle strength, lumbo-pelvic stability, posture, pelvic floor muscle strength, visceral support, and breathing.
Clinical measuring of IRD is performed normally 4.5 cm above, at, and 4.5 below the umbilicus, with categorization as follows: a separation of less than 2 finger breadths is considered non-DRA, mild if it is 2-3 finger breadths, moderate if 3-4, and severe if more than 4. Observed protrusion along the linea alba is almost always categorized as DRA (2).
Prevalence, risk factors, and correlation with lumbo-pelvic pain or dysfunction
Studies on prevalence have found that DRA increases through pregnancy. In around 60% of women, there is natural resolution between Day 1 and 8 weeks after delivery, after which time recovery plateaus.
A recent prospective study by Jorun Bakken et al (2) is the first to provide prevalence data up to 1 year postpartum. The study followed nulliparous pregnant women from pregnancy till 12 months postpartum, and found prevalence to be 33.1%, 60.0%, 45.4% and 32.6%, at week 21, 6 weeks, 6 months and 12 months postpartum, respectively.
On the subject of risk factors, the same study (2) considered a number of them, such as: age, height, weight before this pregnancy, weight gain during pregnancy, delivery mode, baby’s birth weight, benign joint hyper-mobility syndrome, heavy lifting, and level of abdominal and pelvic floor muscle exercise training. This study found that there was a greater likelihood of DRA among women reporting to be exposed to heavy lifting 20 times a week or more, but no other risk factors were found to be significant. The authors suggested that carrying and lifting children could explain the high prevalence postpartum, and that this relationship should be investigated further.
Finally, there is little recent research on the consequences of DRA. One 2009 study (3) found a correlation between lumbo-pelvic pain and DRA. Two more studies are cited by Lee (1) regarding the correlation with pelvic floor dysfunction (incontinence, and prolapse). The consequences of DRA need to be investigated further to be able to support evidence-based physical therapy assessments and intervention decisions.
It’s commonly believed that regular exercise prior to pregnancy and during pregnancy may reduce the risk of developing DRA and reduce its size. Abdominal exercises are also frequently prescribed to postnatal women who have a DRA. Other regularly used non-surgical interventions include postural and back care education, and external support (e.g.tubigrip or corset).
A systematic review by Benjamin, D.R et al (4) investigated the available evidence on these types of interventions and found the following:
- Regarding the use of external compressive garments, the authors did not find conclusive evidence, and state that these garments could be used in addition to TrA exercises to help maintain fascial tension and provide biofeedback to assist with its activation, but more research is necessary on this topic.
- Regarding exercise regimes, the authors found that 5 of the reviewed studies targeted the activation of the transversus abdominis (TrA) muscle. The TrA is the deepest abdominal muscle, and has strong fascial links with the rectus abdominis muscle and the linea alba. Activation of the TrA draws the bellies of the rectus abdominus muscle together, improves the integrity of the linea alba and increases fascial tension, allowing efficient load transference and torque production. The authors concluded that activation of the TrA could be protective of the linea alba and help to prevent or reduce the DRA. A recent observational study by Paul Hodges and Diane Lee (5), has confirmed this opinion, studying the behavior of the linea alba during a curl-up task in women with DRA.
A few newer 2015 studies (6) (7) have also investigated the effects of different types of abdominal exercises on the DRA. In both cases, the results show that curl-up tasks reduce the inter-recti distance, whereas a draw-in maneuver does not, and even it is found to slightly separate them apart. Finally, when the damage sustained to the midline fascial structures is severe, and sufficient tension can no longer be generated through the abdominal wall for resolution of function, a surgical approach may be warranted (1).
After reviewing the current literature, we can summarize that, except in the latter case of severe damage to the linea alba and greater than mean IRD, an effective method to avoid or reduce the DRA is to perform curl-up exercises with pre-activation of the TrA. This provides the appropriate lumbo-pelvic fascial tension, and effective load of the rectus abdominis muscle. This in turn, avoids excessive intra-abdominal pressures that could be damaging for the pelvic floor.
Shift’s Physical Therapy Intervention for Diastasis Recti Abdominis
Our approach at Shift is based on the best conclusions drawn by the literature. Our exercises are based on the aforementioned philosophy, drawing from disciplines such as Pilates, Yoga and the Hypopressive method to develop an exercise program that is tailored to the individual. Every patient is different in their needs, and there is no exercise sequence that fits all. During our initial evaluation we assess the core strength, motor control, and activation patterns, pelvic floor muscle and TrA synergy, spinal and pelvic alignment, as well as myofascial tension and posture, and design a core and DRA exercise program tailored to the patient.
1: Lee DG, Lee LJ, McLaughlin L. Stability, continence and breathing: the role of fascia following pregnancy and delivery. J Bodyw Mov Ther. 2008 Oct;12(4):333-48.
2: Bakken J, Sperstad, K, Tennfjord M, Hilde G, Ellström-Engh M, Bø K. Diastasis recti abdominis during pregnancy and 12 months after childbirth: prevalence, risk factors and report of lumbopelvic pain. Br J Sports Med. 2016 Jun
3: Parker, M; Millar, L; Dugan, Sheila A. Diastasis Rectus Abdominis and Lumbo-Pelvic Pain and Dysfunction-Are They Related?. Journal of Women’s Health Physical Therapy; 2009; 33(2): 15–22
4: Benjamin DR, van de Water AT, Peiris CL. Effects of exercise on diastasis of the rectus abdominis muscle in the antenatal and postnatal periods: a systematic review. Physiotherapy. 2014 Mar;100(1):1-8.
5: Lee D, Hodges PW. Behavior of the Linea Alba During a Curl-up Task in Diastasis Rectus Abdominis: An Observational Study. J Orthop Sports Phys Ther. 2016 Jul;46(7):580-9.
6: Mota P, Pascoal AG, Carita AI, Bø K. The Immediate Effects on Inter-rectus Distance of Abdominal Crunch and Drawing-in Exercises During Pregnancy and the Postpartum Period. J Orthop Sports Phys Ther. 2015 Oct;45(10):781-8.
7: Sancho MF, Pascoal AG, Mota P, Bø K. Abdominal exercises affect inter-rectus distance in postpartum women: a two-dimensional ultrasound study. Physiotherapy. 2015 Sep;101(3):286-91