title: Reliability of electromyographic and torque measures during isometric axial rotation exertions of the trunk.
abstract: OBJECTIVE
  The aim of the present study was to investigate the between-days reliability of electromyographic (EMG) measurement of 6 bilateral trunk muscles and also the torque output in 3 planes during isometric right and left axial rotation at different exertion levels.
  
  
  METHODS
  Ten healthy subjects performed isometric right and left axial rotation at 100, 70, 50 and 30% maximum voluntary contractions in two testing sessions at least 7 days apart. EMG amplitude and frequency analyses of the recorded surface EMG signals were performed for rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured.
  
  
  RESULTS
  For both EMG amplitude and frequency values, good (intraclass correlation coefficient, ICC=0.75-0.89) to excellent (ICC>/=0.90) reliability was found in the 6 trunk muscles at different exertion levels during axial rotation. The reliability of both maximal isometric axial rotation torque and coupling torques in sagittal and coronal planes were found to be excellent (ICC>/=0.93).
  
  
  CONCLUSIONS
  Good to excellent reliability of EMG measures of trunk muscles and torque measurements during isometric axial rotation was demonstrated. This provides further confidence of using EMG and triaxial torque assessment as outcome measures in rehabilitation and in the evaluation of the human performance in the work place.
authors.affiliation: Department of Physiotherapy, The University of Queensland, Brisbane, Australia. rsjoseph@polyu.edu.hk
authors.forename: Joseph K-F
authors.initials: JK
authors.lastname: Ng
authors.forename: Mohamad
authors.initials: M
authors.lastname: Parnianpour
authors.forename: Vaughan
authors.initials: V
authors.lastname: Kippers
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Richardson
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology*; D000328:Adult; D001415:Back / Q000502:physiology; D004576:Electromyography / Q000592:standards*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D015203:Reproducibility of Results; D013131:Spine / Q000502:physiology; D019415:Torque