title: Concurrent validity of the pressure biofeedback unit and surface electromyography in measuring transversus abdominis muscle activity in patients with chronic nonspecific low back pain.
abstract: BACKGROUND
  The Pressure biofeedback unit (PBU) is an assessment tool used in clinical practice and research aimed to indirectly analyze the transversus abdominis (TrA) muscle activity. The concurrent validity of the PBU in a clinically relevant sample is still unclear.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the concurrent validity and diagnostic accuracy of the PBU in measuring TrA muscle activity in patients with chronic nonspecific low back pain.
  
  
  METHODS
  This study was performed using a validation, cross-sectional design. Fifty patients with chronic nonspecific low back pain were recruited for this study. To test the concurrent validity both PBU measures (index test) and superficial electromyographic measures (reference-standard test) were compared and collected by a physical therapist in a series of voluntary contraction maneuvers of TrA muscle.
  
  
  RESULTS
  Participants were on average 22 years old, weighed 63.7 kilos, 1.70 meters height and mean low back pain duration was 1.9 years. It was observed a weak and non-significant Phi coefficient (r=0.2, p<0.20). With regards to diagnostic accuracy tests, our results suggest a low sensitivity (60%) and specificity (60%) of the PBU. The positive predictive value was high (0.8) and negative predictive value was low (0.2).
  
  
  CONCLUSIONS
  Concurrent validity of the PBU in measuring TrA muscle activity in patients with chronic nonspecific low back pain is poor given the low correlation and diagnostic accuracy with superficial EMG.
authors: Physical Therapy Department, Universidade Federal do Ceará, Fortaleza, CE, Brazil. 　pedrolima@ufc.br
authors: Pedro O P
authors: PO
authors: Lima
authors: Rodrigo R
authors: RR
authors: Oliveira
authors: Alberto G
authors: AG
authors: Moura Filho
authors: Maria C F
authors: MC
authors: Raposo
authors: Leonardo O P
authors: LO
authors: Costa
authors: Glória E C
authors: GE
authors: Laurentino
mesh_terms: D000009:Abdominal Muscles / Q000503:physiopathology*; D001676:Biofeedback, Psychology / Q000295:instrumentation / Q000379:methods*; D059350:Chronic Pain / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D015203:Reproducibility of Results; D055815:Young Adult