title: Behavior of the lumbar multifidus during lower extremity movements in people with recurrent low back pain during symptom remission.
abstract: METHODS
  Cross-sectional design.
  
  
  OBJECTIVE
  To investigate lumbar multifidus (LM) thickness differences, using ultrasound imaging in people during remission from recurrent low back pain (LBP) and healthy participants, during the following lower extremity movements: (1) active straight leg raise (ASLR), (2) crook-lying active leg raise (CLR), and (3) prone straight leg raise (PSLR).
  
  
  BACKGROUND
  ASLR, CLR, and PSLR are used clinically to challenge the ability of the trunk muscles to control spinal motion in people with LBP, and it is believed that decreased LM activity is related to altered spinal control in this population. However, it is unclear whether LM behavior differs between healthy individuals and people with recurrent LBP during symptom remission in such tasks.
  
  
  METHODS
  The present study used ultrasound imaging to measure LM percentage thickness change parasagitally at the L4-5 and L5-S1 levels in people with recurrent LBP during symptom remission and in healthy participants, during the ASLR, CLR, and PSLR tasks.
  
  
  RESULTS
  LM percentage thickness change was greater in the recurrent LBP group than in healthy participants during the PSLR task (P<.01) and greater in both groups during the PSLR than the ASLR and CLR tasks (P<.01). LM percentage thickness change was greatest at L4-5 in both groups (P<.01) and during all tasks (P≤.02). No difference was found in LM percentage thickness change between groups in either the ASLR (P = .70) or CLR (P = .69) task.
  
  
  CONCLUSIONS
  These data suggest that, during symptom remission, individuals with recurrent LBP, compared to healthy individuals, may have greater activity in at least some parts of the LM. Further investigation is required to determine whether the LM percentage thickness change observed in this study may be explained by differential changes in deep and/or superficial fibers of LM activity. This observation may have implications for clinical practice, but requires further investigation.
authors.affiliation: The University of Queensland, Brisbane, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Macdonald
authors.forename: Anna P
authors.initials: AP
authors.lastname: Dawson
authors.forename: Paul W
authors.initials: PW
authors.lastname: Hodges
mesh_terms: D000704:Analysis of Variance; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000534:rehabilitation*; D035002:Lower Extremity / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008161:Lumbosacral Region / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015203:Reproducibility of Results; D014463:Ultrasonography; D055815:Young Adult