Effect of pelvic floor and transversus abdominis muscle contraction on inter-rectus distance in postpartum women: a cross-sectional experimental study

Physiotherapy. 2019 Sep;105(3):315-320. doi: 10.1016/j.physio.2018.08.009. Epub 2018 Oct 25.


Objectives: To investigate the effect of acute isometric contraction of the pelvic floor muscles (PFM) and transversus abdominis muscle (TrAM) on inter-rectus distance (IRD) from resting values in postpartum women with diastasis rectus abdominis (DRA).

Design: Cross sectional experimental study.

Setting: Physiotherapy clinic.

Participants: Thirty eight postpartum women presenting with DRA of at least two finger widths.

Methods: Two dimensional ultrasound images of IRD were recorded using a linear probe (5 to 10MHz) at rest, during PFM contraction, during TrAM contraction, and during combined PFM and TrAM contraction. IRD data were normally distributed.

Main outcome measure: Change in IRD.

Results: There was a significant increase in IRD during PFM and TrAM contraction compared with IRD at rest. At 2cm above the umbilicus, mean PFM was 26.9 [standard deviation (SD) 8.8] mm vs rest 25.7 (SD 8.5) mm {mean difference 1.2 [95% confidence interval (CI) 0.7 to 1.7] mm}; and mean TrAM was 28.4 (SD 9.0) mm vs rest 25.7 (SD 8.5) mm [mean difference 2.8 (95% CI 1.9 to 3.6) mm]. Similarly, 2cm below the umbilicus, mean PFM was 22 (SD 8.3) mm vs rest 21 (SD 7.9) mm [mean difference 0.9 (95% CI 0.4 to 1.6) mm]; and mean TrAM was 23.3 (SD 8.7) mm vs rest 21 (SD 7.9) mm [mean difference 2.3 (95% CI 1.5 to 3.1) mm]. Combined TrAM and PFM contraction measured 2cm above the umbilicus caused the greatest increase in IRD: mean PFM+TrAM 29.6 (SD 9.4) mm vs rest 25.7 (SD 8.5) mm [mean difference 3.9 (95% CI 2.8 to 5.0) mm].

Conclusion: Both PFM and TrAM contraction, and combined PFM and TrAM contraction increased IRD in postpartum women with DRA.

Keywords: Diastasis rectus abdominis; Inter-rectus distance; Measurement; Pelvic floor; Transversus abdominis; Ultrasonography.

MeSH terms

  • Abdominal Muscles / physiology*
  • Adult
  • Cross-Sectional Studies
  • Diastasis, Muscle / diagnostic imaging
  • Diastasis, Muscle / physiopathology*
  • Female
  • Humans
  • Isometric Contraction*
  • Pelvic Floor / physiology*
  • Postpartum Period
  • Pregnancy
  • Pregnancy Complications / diagnostic imaging
  • Pregnancy Complications / physiopathology*
  • Rectus Abdominis / diagnostic imaging
  • Rectus Abdominis / physiopathology*
  • Ultrasonography