title: Adaptation of muscles of the lumbar spine to sudden imbalance in patients with lower back pain caused by military training.
abstract: OBJECTIVE
  This study aims to investigate the effects of sudden load changes (expected and unexpected imbalance) on the activity of muscles of the lumbar spine and their central motor control strategy in military personnel with or without chronic low back pain (LBP).
  
  
  METHODS
  Bilateral sudden imbalance was examined (2 × 2 factorial design).
  
  
  METHODS
  The 117th PLA Hospital, Hangzhou, China
  
  
  METHODS
  Twenty-one male subjects with lower back pain and 21 male healthy control subjects were active members of the Nanjing Military Region land forces.
  
  
  METHODS
  Independent variables: LBP vs. healthy controls and imbalance anticipation (expected and unexpected imbalance).
  
  
  METHODS
  rapid reaction time (RRT) and intensity of rapid reaction (IRR) of bilateral lumbar (L3-L4) erector spinae (ES), lumbar (L5-S1) multifidus (MF), and abdominal external oblique muscles. Results Under expected or unexpected sudden imbalance conditions, subjects with LBP demonstrated significantly greater IRR than healthy controls in ipsilateral and contralateral ES and MF, respectively (P < 0.05 for all). IRR of contralateral ES was significantly larger than that of the ipsilateral ES. A significant group effect of RRT of both ipsilateral and contralateral ES muscles and a significant time expectation effect on RRT of contralateral MF muscles were also observed. RRT of the contralateral ES muscles was significantly lower than that of the ipsilateral ES muscles (P < 0.001).
  
  
  CONCLUSIONS
  Sudden imbalance prolonged RRT of selected trunk muscles in patients with chronic LBP. The activation amplitude increased. The results may provide a theoretical basis for a study on the pathogenesis of chronic LBP.
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Jian-guo
authors.initials: JG
authors.lastname: Shi
authors.forename: Hong
authors.initials: H
authors.lastname: Ye
authors.forename: Zhi-rong
authors.initials: ZR
authors.lastname: Liu
authors.forename: Long-bao
authors.initials: LB
authors.lastname: Zheng
authors.forename: Zhi-ming
authors.initials: ZM
authors.lastname: Ni
authors.forename: Liang-quan
authors.initials: LQ
authors.lastname: Fan
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Zhen-hai
authors.initials: ZH
authors.lastname: Hou
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D064131:Back Muscles / Q000294:innervation / Q000503:physiopathology*; D007839:Functional Laterality; D006801:Humans; D017116:Low Back Pain / Q000150:complications* / Q000209:etiology; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D008889:Military Personnel; D004856:Postural Balance / Q000502:physiology*; D011930:Reaction Time; D012678:Sensation Disorders / Q000209:etiology*; D013663:Teaching; D055815:Young Adult
keywords: Back pain; Muscle response; Sudden load