Abdominal exercises affect inter-rectus distance in postpartum women: a two-dimensional ultrasound study

ObjectivesTo compare inter-rectus distance (IRD) at rest between women who had a vaginal delivery with women who had a caesarean section, and to describe the effect of different abdominal exercises on IRD.SettingPhysiotherapy practice.DesignCross-sectional experimental study.ParticipantsThirty-eight postpartum primiparous mothers with a singleton baby (vaginal delivery: n = 23; caesarean section: n = 15).InterventionsTwo-dimensional ultrasound images from the abdominal wall were recorded at rest and at the end position of abdominal crunch, drawing-in and drawing-in + abdominal crunch exercises. IRD measurements at rest, above and below the umbilicus, were compared between the two groups (vaginal delivery and caesarean section). IRD was also measured above and below the umbilicus during three abdominal exercises in both groups.Main outcome measuresIRD 2 cm above and below the umbilicus.ResultsNo significant differences in IRD, either above or below the umbilicus, were found between the vaginal delivery and caesarean section groups. IRD above the umbilicus was significantly reduced during abdominal crunch exercises compared with at rest {mean 21.7 [standard deviation (SD) 7.6] mm vs 25.9 (SD 9.0) mm; mean difference 4.2 mm; 95% confidence interval (CI) 0.5 to 7.9}. IRD below the umbilicus was significantly greater during drawing-in exercises compared with at rest [16.0 (SD 8.1) mm vs 11.4 (SD 4.9) mm; mean difference 4.5 mm; 95% CI 1.6 to 7.4].ConclusionIn contrast to existing recommendations for abdominal strength training among postpartum women, this study found that abdominal crunch exercises reduced IRD, and drawing-in exercises were ineffective for reducing IRD. Further basic studies and randomised controlled trials are warranted to explore the effect of abdominal training on IRD.