title: Effect of mental processing on low back load while lifting an object.
abstract: METHODS
  Biomechanical study using a 3D motion analysis system conducted in a laboratory setting.
  
  
  OBJECTIVE
  To determine the effect of mental processing on low back load during lifting.
  
  
  BACKGROUND
  In addition to ergonomic factors such as frequent lifting, work-related psychosocial factors are significant in the onset of disabling back pain. Although the ergonomic effects on low back load while lifting have been investigated and are widely accepted in the workplace, few studies have investigated the effect of psychosocial factors on low back load while lifting.
  
  
  METHODS
  Thirteen healthy subjects lifted a box from the ground in 4 different lifting tasks in randomized order: (1) squat posture with knees flexed; (2) stoop posture with knees extended; (3) squat posture with mental processing using arithmetic tasks; and (4) stoop posture with mental processing using arithmetic tasks. We used a 3D motion analysis system and 4 force plates to record kinematic and kinetic data. We calculated dynamic triaxial low back joint moments and low back compression force as index parameters of low back load under these experimental conditions.
  
  
  RESULTS
  Mental processing significantly increased peak low back compression force and low back extension moment, but not lateral flexion or rotation moment, while lifting in both lifting postures. Also, mental processing increased trunk bending angles in the squat posture. Although a tendency for decreased pelvic forward tilt was observed, mental processing did not significantly decrease forward pelvic tilt in the stoop posture.
  
  
  CONCLUSIONS
  Mental processing during lifting tasks seems to affect both trunk and pelvis angles in the sagittal plane for squat and stoop postures, resulting in increased low back load. The present findings might help explain the effect of ergonomic demands of lifting tasks as well as psychosocial factors responsible for the onset of disabling back pain.
  
  
  METHODS
  2.
authors.affiliation: Department of Health Science, International University of Health and Welfare, Kitakanemaru, Otawara, Tochigi, Japan. katsuhir@iuhw.ac.jp
authors.forename: Junji
authors.initials: J
authors.lastname: Katsuhira
authors.forename: Ko
authors.initials: K
authors.lastname: Matsudaira
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Iwakiri
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kimura
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Ohashi
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Ono
authors.forename: Sho
authors.initials: S
authors.lastname: Sugita
authors.forename: Keisuke
authors.initials: K
authors.lastname: Fukuda
authors.forename: Soyoka
authors.initials: S
authors.lastname: Abe
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Maruyama
mesh_terms: D000704:Analysis of Variance; D001415:Back / Q000502:physiology*; D001696:Biomechanical Phenomena; D006801:Humans; D007596:Joints / Q000502:physiology; D007717:Knee / Q000502:physiology; D017770:Lifting; D017116:Low Back Pain / Q000503:physiopathology; D008297:Male; D008606:Mental Processes / Q000502:physiology; D011187:Posture / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D013131:Spine / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult