title: Inter-rectus distance in postpartum women can be reduced by isometric contraction of the abdominal muscles: a preliminary case-control study.
abstract: OBJECTIVE
  To determine the effect of isometric contraction of the abdominal muscles on inter-rectus distance in postpartum women.
  
  
  METHODS
  Preliminary case-control study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Ten postpartum women {mean age 30 [standard deviation (SD) 4] years; mean weight 58 (SD 7) kg; mean height 159 (SD 4) cm} and 10 nulliparous (control) women [mean age 28 (SD 2) years; mean weight 56 (SD 6) kg; mean height 160 (SD 6) cm].
  
  
  METHODS
  Ultrasound images from the anterior abdominal wall were recorded at rest (supine position) and during an abdominal isometric contraction, with the subject actively performing an abdominal crunch (crook lying position). Two-way analysis of variance was used to compare the inter-rectus distance between groups (postpartum vs control) and between levels of abdominal muscle activation (rest vs isometric contraction).
  
  
  METHODS
  Inter-rectus distance 2cm above the level of the umbilicus.
  
  
  RESULTS
  The inter-rectus distance was significantly greater in the postpartum group compared with the control group [14.7 (SD 3.1) mm vs 9.6 (SD 2.8) mm; mean difference 5.1mm; 95% confidence interval (CI) 3.4 to 6.8]. The inter-rectus distance was significantly lower during isometric contraction compared with rest [10.7 (SD 3.1) mm vs 13.4 (SD 3.1) mm; mean difference 2.8mm; 95% CI 1.2 to 4.5]. No interaction was found between group and muscle contraction.
  
  
  CONCLUSIONS
  The inter-rectus distance was significantly higher in postpartum women compared with controls, and significantly lower during isometric contraction of the abdominal muscles (abdominal crunch) compared with rest.
authors.affiliation: Universidade de Lisboa, Faculdade de Motricidade Humana, CIPER, LBMF, Lisbon, Portugal. Electronic address: gpascoal@fmh.ulisboa.pt.
authors.forename: A G
authors.initials: AG
authors.lastname: Pascoal
authors.affiliation: Universidade de Lisboa, Faculdade de Motricidade Humana, CIPER, LBMF, Lisbon, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Dionisio
authors.affiliation: Universidade de Lisboa, Faculdade de Motricidade Humana, CIPER, LBMF, Lisbon, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Cordeiro
authors.affiliation: Universidade de Lisboa, Faculdade de Motricidade Humana, CIPER, LBMF, Lisbon, Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Mota
mesh_terms: D016022:Case-Control Studies; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D049590:Postpartum Period; D011247:Pregnancy; D017568:Rectus Abdominis / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D012016:Reference Values; D018570:Risk Assessment; D014463:Ultrasonography; D055815:Young Adult
keywords: Abdominal strength exercises; Diastasis abdominis; Inter-rectus distance; Post partum; Ultrasound scanning