title: Psoas and quadratus lumborum muscle asymmetry among elite Australian Football League players.
abstract: OBJECTIVE
  In this study, asymmetry relative to the preferred kicking leg was determined if it exists for the psoas and quadratus lumborum muscles among elite Australian Football League (AFL) players.
  
  
  METHODS
  AFL players were assessed at three time points from 2005 to 2007 (start of preseason, end of season and end of preseason training). MRI was used to determine the cross-sectional areas (CSAs) of the psoas and quadratus lumborum muscles at the L4-L5 vertebral level (psoas) and the L3-L4 vertebral level (quadratus lumborum).
  
  
  METHODS
  MRI was performed in a hospital setting.
  
  
  METHODS
  54 professional AFL players were eligible to participate in this study. The number of subjects at each of the three time points was 36 for time 1 (T1 Nov 2005), 31 for time 2 (T2 Aug 2006) and 43 for time 3 (T3 Feb Mar 2007).
  
  
  METHODS
  The repeated measures factor in the analyses was "asymmetry", defined as "ipsilateral" or "contralateral" to preferred kicking leg. Number of injuries (coded as 0, 1, 2 or more) was also included as a risk factor.
  
  
  METHODS
  The dependent variables were the CSAs of the psoas and quadratus lumborum muscles.
  
  
  RESULTS
  At all three time points, the CSA of the psoas muscle was significantly greater ipsilateral to the kicking leg, while the CSA of the quadratus lumborum muscle was significantly greater on the side contralateral to the kicking leg. Asymmetry in muscle size was not related to number of injuries.
  
  
  CONCLUSIONS
  Asymmetry of the psoas and the quadratus lumborum muscles exists in elite AFL players.
authors.affiliation: Division of Physiotherapy, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, 4072 Queensland, Australia. j.hides1@uq.edu.au
authors.forename: J
authors.initials: J
authors.lastname: Hides
authors.forename: T
authors.initials: T
authors.lastname: Fan
authors.forename: W
authors.initials: W
authors.lastname: Stanton
authors.forename: P
authors.initials: P
authors.lastname: Stanton
authors.forename: K
authors.initials: K
authors.lastname: McMahon
authors.forename: S
authors.initials: S
authors.lastname: Wilson
mesh_terms: D000009:Abdominal Muscles / Q000033:anatomy & histology*; D000328:Adult; D000704:Analysis of Variance; D005538:Football; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D016658:Psoas Muscles / Q000033:anatomy & histology*; D011793:Queensland