title: Influence of posture on the range of axial rotation and coupled lateral flexion of the thoracic spine.
abstract: OBJECTIVE
  This study examines the influence of posture on the range of axial rotation of the thorax and the range and direction of the coupled lateral flexion.
  
  
  METHODS
  The ranges of mid thoracic axial rotation and coupled lateral flexion were measured in 52 asymptomatic subjects (aged 18-43 years) using an optical motion analysis system. To examine the influence of posture on primary and coupled motion, we initiated axial rotation from a neutral sitting posture and from end-range thoracic flexion and extension.
  
  
  RESULTS
  There was a significant decrease in the range of thoracic rotation in flexion compared with the neutral and extended postures (P < .001). The mean range of coupled lateral flexion was 8.9% of the axial rotation range in the neutral posture and increased to 14.3% and 23.2% in the extended and flexed postures, respectively. Patterns of coupled motion varied between subjects, but an ipsilateral pattern was more common in the flexed posture, whereas a contralateral pattern was more common in the neutral and extended postures.
  
  
  CONCLUSIONS
  The ranges and patterns of coupled motion of the thorax appear to be strongly influenced by the posture from which the movement is initiated. This has important implications in relation to the interpretation of clinical tests of thoracic motion and in consideration of mechanisms of development of thoracic pain disorders.
authors.affiliation: School of Physiotherapy, Curtin University of Technology, Perth, Western Australia. s.edmondston@curtin.edu.au
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Edmondston
authors.forename: Mathew
authors.initials: M
authors.lastname: Aggerholm
authors.forename: Suzanne
authors.initials: S
authors.lastname: Elfving
authors.forename: Neil
authors.initials: N
authors.lastname: Flores
authors.forename: Christopher
authors.initials: C
authors.lastname: Ng
authors.forename: Richard
authors.initials: R
authors.lastname: Smith
authors.forename: Kevin
authors.initials: K
authors.lastname: Netto
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D011187:Posture; D016059:Range of Motion, Articular / Q000502:physiology*; D012984:Software; D013904:Thoracic Vertebrae / Q000502:physiology*