Correlation between self-reported low back pain and morphological changes in abdominal wall muscles

BACKGROUND: Morphological changes in the abdominal wall muscle in diastasis recti abdominis (DRA) patients with low back pain (LBP) symptoms and whether there is a wider interrectus distance (IRD) remain unclear. OBJECTIVE: The aim of this study was to determine the correlation between DRA severity and LBP and the morphological differences in abdominal wall muscles between patients who presented with symptoms of LBP and those who were asymptomatic. METHODS: A total of 57 postpartum DRA patients were enrolled, including 21 without LBP, 36 with LBP, and 30 healthy nulliparous women. The numerical rating scale (NRS) was used to evaluate the degree of LBP. The IRD and muscle thickness of the abdominal muscles were measured via an ultrasonography device at the end of a natural breathing cycle. RESULTS: The abdominal muscles of the rectus abdominis (RA), external oblique muscle (EO), and transversus abdominis (TrA) in the DRA patients were significantly thinner than those in the control group (p< 0.05), whereas the difference in the internal oblique muscle (IO) was not significant (p> 0.05). There were no statistically significant differences in abdominal muscle thickness or the IRD regardless of whether the patients with DRA had LBP symptoms, with similar findings between the NRS score and DRA severity (P> 0.05). CONCLUSION: In DRA patients within one year postpartum, no significant difference was found in the severity of DRA or abdominal muscles, regardless of whether they were complicated by LBP symptoms. Shortening the IRD alone may not be beneficial for improving LBP symptoms in DRA patients. The relationship between DRA and LBP and the role of the abdominal muscles in postpartum LBP should be interpreted with caution.