title: Is activation of transversus abdominis and obliquus internus abdominis associated with long-term changes in chronic low back pain? A prospective study with 1-year follow-up.
abstract: OBJECTIVE
  To investigate associations between deep abdominal muscle activation and long-term pain outcome in chronic non-specific low back pain (LBP).
  
  
  METHODS
  Recruitment of transversus abdominis and obliquus internus abdominis during the abdominal drawing-in manoeuvre was recorded by B-mode ultrasound and anticipatory onset of deep abdominal muscle activity with M-mode ultrasound. Recordings were done before and after 8 weeks with guided exercises for 109 patients with chronic non-specific LBP. Pain was assessed with a numeric rating scale (0-10) before and 1 year after intervention. Associations between muscle activation and long-term pain were examined by multiple linear and logistic regression methods.
  
  
  RESULTS
  Participants with a combination of low baseline lateral slide in transversus abdominis and increased slide after intervention had better odds for long-term clinically important pain reduction (≥2 points on the numeric rating scale) compared with participants with small baseline slide and no improvement in slide (OR 14.70, 95% CI 2.41 to 89.56). There were no associations between contraction thickness ratios in transversus abdominis or obliquus internus abdominis and pain at 1-year follow-up. Transversus abdominis lateral slide before intervention was marginally associated with a lower OR for clinically important improvement in pain at 1-year follow-up (OR 0.76, 95% CI 0.62 to 0.93). Delayed onset of the abdominal muscles after the intervention period was weakly associated with higher long-term pain.
  
  
  CONCLUSIONS
  Improved transversus abdominis lateral slide among participants with low baseline slide was associated with clinically important long-term pain reduction. High baseline slide and delayed onset of abdominal muscles after the intervention period were weakly associated with higher pain at 1-year follow-up. Clinical Trial Registration number The study was preregistered in ClinicalTrials.gov with identifier NCT00201513.
authors.affiliation: Faculty of Medicine, Department of Public Health and General Practice, Norwegian University of Science and Technology, Medisinsk teknisk forskningssenter (MTFS), 7489 Trondheim, Norway. monica.unsgaard.tondel@ntnu.no
authors.forename: Monica
authors.initials: M
authors.lastname: Unsgaard-Tøndel
authors.forename: Tom Ivar
authors.initials: TI
authors.lastname: Lund Nilsen
authors.forename: Jon
authors.initials: J
authors.lastname: Magnussen
authors.forename: Ottar
authors.initials: O
authors.lastname: Vasseljen
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology*; D000328:Adult; D002908:Chronic Disease; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology / Q000628:therapy*; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D010147:Pain Measurement; D011446:Prospective Studies; D055815:Young Adult