title: A comparison of abdominal muscle thickness changes after a lifting task in subjects with and without chronic low-back pain.
abstract: OBJECTIVE
  Using ultrasound imaging, the abdominal muscles' response to the back extensor muscle fatigue was assessed in subjects with chronic low-back pain (CLBP).
  
  
  BACKGROUND
  Lumbar muscle fatigue is a common occurrence among workers. Alteration in motor coordination is one consequence of muscular fatigue. According to previous studies, CLBP subjects use their back and abdominal muscles in different ways, but questions remain about abdominal muscle responses to back muscle fatigue in CLBP patients.
  
  
  METHODS
  Thirteen CLBP patients and 15 healthy subjects participated in this study. The thickness of abdominal muscles-including transverse abdominis (TrA), internal oblique abdominis (IO), and external oblique abdominis (EO) muscles-was measured in standing position with and without axial loads before and after a lifting fatigue task.
  
  
  RESULTS
  The results reveal a significant difference for the main effects of group on percentage of change in TrA thickness (F = 8.9, p = .004). Percentage of change in thickness of TrA was 10% greater in the CLBP group. Although IO thickness displayed greater percentage of change in the CLBP group, the difference between groups was not significant.
  
  
  CONCLUSIONS
  Abdominal muscle behavior changes with back-muscle fatigue in both healthy and CLBP subjects, but responses were more exaggerated in CLBP patients.
  
  
  CONCLUSIONS
  Ultrasound imaging technique can provide critical information about the effect of fatigue on spinal muscle activation and consequently about the stability of the spine. As a more applicable and easy technique, ergonomists can use ultrasound imaging in musculoskeletal system assessment in worker populations in future studies.
authors: Tarbiat Modares University, Tehran, Iran.
authors: Tahere
authors: T
authors: Seyed Hoseinpoor
authors: Tarbiat Modares University, Tehran, Iran kahrizis@modares.ac.ir.
authors: Sedighe
authors: S
authors: Kahrizi
authors: Tehran University of Medical Sciences, Tehran, Iran.
authors: Bahram
authors: B
authors: Mobini
authors: Islamic Azad University, Dezful, Iran.
authors: Mohsen
authors: M
authors: Naji
mesh_terms: D000009:Abdominal Muscles / Q000000981:diagnostic imaging / Q000502:physiology*; D000328:Adult; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D017770:Lifting; D017116:Low Back Pain / Q000453:epidemiology / Q000503:physiopathology*; D014463:Ultrasonography; D055815:Young Adult
keywords: abdominal muscles; back pain; fatigue; thickness; ultrasonography