title: Association between changes in electromyographic signal amplitude and abdominal muscle thickness in individuals with and without lumbopelvic pain.
abstract: METHODS
  Validation study.
  
  
  OBJECTIVE
  To investigate the association between changes in electromyographic (EMG) signal amplitude and sonographic measures of muscle thickness of 4 abdominal muscles, during 2 clinical tests, in adults with and without lumbopelvic pain.
  
  
  BACKGROUND
  There is a trend in rehabilitation to use ultrasound imaging (USI) to determine the extent of abdominal muscle contraction. However, the literature investigating the relationship between abdominal muscle thickness change and level of activation is inconclusive and has not included clinically relevant tasks.
  
  
  METHODS
  Simultaneous recording from fine-wire EMG and USI was performed for 4 abdominal muscles, in 7 adults with lumbopelvic pain (mean ± SD age, 29.7 ± 12.0 years) and 7 adults without lumbopelvic pain (32.0 ± 10.6 years), during an active straight leg raise (ASLR) test and an abdominal drawing-in maneuver (ADIM). Cross-correlation functions and linear regression analyses were used to describe the relationship between the 2 measures. Analyses of variance were used to compare individuals with and without lumbopelvic pain, with an alpha set at .05.
  
  
  RESULTS
  Across all muscles, peak cross-correlation values were low (ASLR, r = 0.28 ± 0.09; ADIM, r = 0.35 ± 0.11), and there was large variability in associated time lags (ASLR, τ = 0.69 ± 2.56 seconds; ADIM, τ = 0.53 ± 3.75 seconds). Regression analyses did not detect a systematic pattern of association between EMG signal amplitude and USI measurements, and analyses of variance revealed no differences between cohorts.
  
  
  CONCLUSIONS
  These results suggest a weak relationship between EMG amplitude and abdominal muscle thickness change measured with USI during the ADIM and ASLR, and raise questions about thickness change derived from USI as a measure of muscular activity for the abdominal musculature.
authors: University of Calgary, Calgary, Alberta, Canada. 　j.whittaker@ucalgary.ca
authors: Jackie L
authors: JL
authors: Whittaker
authors: Linda
authors: L
authors: McLean
authors: Joanne
authors: J
authors: Hodder
authors: Martin B
authors: MB
authors: Warner
authors: Maria J
authors: MJ
authors: Stokes
mesh_terms: D000009:Abdominal Muscles / Q000000981:diagnostic imaging / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D016014:Linear Models; D017116:Low Back Pain / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D017699:Pelvic Pain / Q000503:physiopathology; D014463:Ultrasonography; D055815:Young Adult