title: The crunch factor's role in golf-related low back pain.
abstract: BACKGROUND
  The golf swing exposes the spine to complex torsional, compressive, and shearing loads that increase a player's risk of injury. The crunch factor (CF) has been described as a measure to evaluate the risk of low back injuries in golfers and is based on the notion that lateral flexion and axial trunk rotation jointly contribute to spinal degeneration. However, few studies have evaluated the appropriateness of this measure in golfers with low back pain (LBP).
  
  
  OBJECTIVE
  To objectively examine the usefulness of the CF as a measure for assessing the risk of low back injury in golfers.
  
  
  METHODS
  Field-based research using a cross-sectional design.
  
  
  METHODS
  This research used three-dimensional motion analysis to assess the golf swings of 12 golfers with LBP and 15 asymptomatic controls. Three-dimensional kinematics were derived using Vicon Motus, and the CF was calculated as the instantaneous product of axial trunk rotation velocity and lateral trunk flexion angle.
  
  
  RESULTS
  Maximum CFs and their timings were not significantly different between the symptomatic and asymptomatic groups. Furthermore, for those golfers who produced higher CFs (irrespective of the group), the increased magnitude could not be attributed to an increased axial angular trunk velocity or lateral flexion angle, but rather to a concomitant increase in both of these variables.
  
  
  CONCLUSIONS
  The findings suggested that although the fundamental concepts that underpin the CF seem sensible, this measure does not appear to be sensitive enough to distinguish golfers with LBP from the asymptomatic players.
authors.affiliation: School of Exercise Science, Faculty of Health Sciences, Australian Catholic University, PO Box 456, Virginia, Queensland 4014, Australia. Electronic address: michael.cole@acu.edu.au.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Cole
authors.affiliation: School of Mechanical Engineering, Faculty of Engineering, Computer and Mathematical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Grimshaw
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006055:Golf / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D017116:Low Back Pain / Q000209:etiology / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010147:Pain Measurement; D015203:Reproducibility of Results; D012399:Rotation; D060726:Torso / Q000502:physiology*
keywords: Biomechanics; Golf swing; Injury prevention; Lumbar spine; Trunk motion