Effect of Abdominal Muscle Training on Inter-recti Distance and Prevalence of Diastasis Recti Abdominis in Postpartum Primi- and Multiparous Women: A Randomized Controlled Trial

BACKGROUND: DRA is defined as an impairment with midline separation of the two rectus abdominis muscles along the linea alba. The condition affects a significant number of women during the antenatal- and postnatal period. Today there is a strong focus on the pregnant woman's appearance, especially through social media. Webpages and apps recommend how women should stay thin and get back into shape with "a flat tummy" at an early stage of the postpartum period. There are easily available advices on how to get rid of what is named "the mum's belly" (e.g.mammamage.se, breakingmuscle.com, befitmom.com, babybellybelt.com, tummyzip.com). A systematic review of the scientific literature has found none or very weak evidence behind any of these advices. DRA is diagnosed by measuring the distance between the median borders of the two rectus abdominis; IRD, and ultrasound has been found to have the best intra- and inter-tester reliability with Intraclass Correlation Coefficient (ICC) > 0.9. In a systematic review by Benjamin et al. (2014), 8 studies in treatment of DRA using abdominal exercises were found: four case studies, two retrospective observational studies, one quasi-experimental post-test study and one small RCT of a brief training intervention. A new search on Pubmed of July 2019 found six additional RCTs using abdominal exercises in treatment of DRA. The studies differ in methodological and interventional quality and results differ between studies. Given the limited research data, use of different outcome measures and cut-off point for diastasis in published studies, there is currently no consensus on which abdominal exercises to recommend to narrow the diastasis. AIMS: The aim of this study is to assess the effect of abdominal muscle training on IRD and prevalence of DRA in postpartum primi- and multiparous women. STUDY DESIGN AND METHODS: Before starting this RCT, an experimental cross-sectional study investigating the acute effect of different abdominal- and pelvic floor exercises on IRD in women with DRA will be conducted. Based on findings from the experimental cross-sectional study, we will choose exercises that narrow the IRD for the RCT's exercise program. Women will respond to an electronic questionnaire sent by email before they meet for the clinical assessments, before and after the intervention period. Women diagnosed with DRA giving informed consent are assessed at baseline with 2D ultrasound measurements of IRD, abdominal muscle strength tests and the Oswestry Low Back Disability Index (ODI), Pelvic Girdle Questionnaire (PGQ) and (Pelvic Floor Disability Index) PFDI-20. After baseline testing the participants are randomly allocated to either an exercise or control group. Randomization will be computer-generated, in blocks of 4 with concealed allocation. Randomization will be provided by a person not involved in assessments of outcome. The outcome assessor will be blinded for group allocation. After the 3 month training period, both the exercise and control group will be reassessed with 2D ultrasound, abdominal muscle strength and endurance tests and the ODI, PGQ and PFDI-20.