title: Measurement properties of the pressure biofeedback unit in the evaluation of transversus abdominis muscle activity: a systematic review.
abstract: BACKGROUND
  Measurements from pressure biofeedback units (PBUs) can be used to evaluate the activity of the transversus abdominis (TrA) muscle indirectly. These measurements can classify patients or monitor the progress of treatment programmes for people with low back pain.
  
  
  OBJECTIVE
  To systematically review studies on the measurement properties of PBUs for the assessment of TrA activity.
  
  
  METHODS
  Eligible studies were identified through searches of PUBMED, CINAHL and BIREME (1990 to 2009). In addition, hand searches of journals and citation tracking were performed.
  
  
  METHODS
  Full-text studies involving any type of clinimetric tests of PBU measurement for the assessment of TrA activity were selected.
  
  
  METHODS
  Two independent reviewers selected the studies, extracted the data and assessed methodological quality.
  
  
  RESULTS
  Due to the heterogeneity of study designs and statistical analysis, it was not possible to pool the data for a meta-analysis.
  
  
  RESULTS
  Six studies met the inclusion criteria. These studies were typically of low quality and recruited healthy subjects rather than patients with low back pain. The studies found moderate to good reproducibility (intra-class correlation coefficients from 0.47 to 0.82) and acceptable construct validity (intra-class correlation coefficients from 0.48 to 0.90).
  
  
  CONCLUSIONS
  The current evidence about the measurement properties of PBUs for the assessment of TrA activity is mainly based on studies with suboptimal designs, and the findings from these studies are likely to be overly optimistic. The most important clinical questions about the measurement properties of PBUs for the assessment of TrA activity are yet to be answered.
authors.affiliation: Masters Programme in Physical Therapy, Universidade Federal de Pernambuco, Brazil. pedrofisioterapia@hotmail.com
authors.forename: Pedro Olavo
authors.initials: PO
authors.lastname: de Paula Lima
authors.forename: Rodrigo Ribeiro
authors.initials: RR
authors.lastname: de Oliveira
authors.forename: Leonardo Oliveira Pena
authors.initials: LO
authors.lastname: Costa
authors.forename: Glória Elizabeth Carneiro
authors.initials: GE
authors.lastname: Laurentino
mesh_terms: D000009:Abdominal Muscles / Q000000981:diagnostic imaging* / Q000502:physiology; D001676:Biofeedback, Psychology / Q000379:methods; D006801:Humans; D009135:Muscular Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000534:rehabilitation; D026741:Physical Therapy Modalities; D014463:Ultrasonography / Q000379:methods* / Q000592:standards*