title: Flexion and rotation of the trunk and lifting at work are risk factors for low back pain: results of a prospective cohort study.
abstract: METHODS
  A 3-year prospective cohort study among workers of 34 companies in the Netherlands.
  
  
  OBJECTIVE
  To investigate the relation between flexion and rotation of the trunk and lifting at work and the occurrence of low back pain.
  
  
  BACKGROUND
  Previous studies on work-related physical risk factors for low back pain either lacked quantification of the physical load or did not take confounding by individual and psychosocial factors into account.
  
  
  METHODS
  The study population consisted of 861 workers with no low back pain at baseline and complete data on the occurrence of low back pain during the 3-year follow-up period. Physical load at work was assessed by means of analyses of video-recordings. Information on other risk factors and the occurrence of low back pain was obtained by means of self-administered questionnaires.
  
  
  RESULTS
  An increased risk of low back pain was observed for workers who worked with the trunk in a minimum of 60 degrees of flexion for more than 5% of the working time (RR 1.5, 95% CI 1.0-2.1), for workers who worked with the trunk in a minimum of 30 degrees of rotation for more than 10% of the working time (RR 1.3, 95% CI 0.9-1. 9), and for workers who lifted a load of at least 25 kg more than 15 times per working day (RR 1.6, 95% CI 1.1-2.3).
  
  
  CONCLUSIONS
  Flexion and rotation of the trunk and lifting at work are moderate risk factors for low back pain, especially at greater levels of exposure.
authors.affiliation: TNO Work and Employment, Hoofddorp, The Netherlands. L.Hoogendoorn@arbeid.tno.nl
authors.forename: W E
authors.initials: WE
authors.lastname: Hoogendoorn
authors.forename: P M
authors.initials: PM
authors.lastname: Bongers
authors.forename: H C
authors.initials: HC
authors.lastname: de Vet
authors.forename: M
authors.initials: M
authors.lastname: Douwes
authors.forename: B W
authors.initials: BW
authors.lastname: Koes
authors.forename: M C
authors.initials: MC
authors.lastname: Miedema
authors.forename: G A
authors.initials: GA
authors.lastname: Ariëns
authors.forename: L M
authors.initials: LM
authors.lastname: Bouter
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D017770:Lifting; D017116:Low Back Pain / Q000453:epidemiology*; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D009784:Occupational Diseases / Q000453:epidemiology*; D011187:Posture; D011446:Prospective Studies; D012399:Rotation; D014741:Video Recording; D016474:Weight-Bearing