title: Hip strength and range of motion: Normal values from a professional football league.
abstract: OBJECTIVE
  To determine the normal profiles for hip strength and range of motion (ROM) in a professional football league in Qatar, and examine the effect of leg dominance, age, past history of injury, and ethnicity on these profiles.
  
  
  METHODS
  Cross-sectional cohort study.
  
  
  METHODS
  Participants included 394 asymptomatic, male professional football players, aged 18-40 years. Strength was measured using a hand held dynamometer with an eccentric test in side-lying for hip adduction and abduction, and the squeeze test in supine with 45° hip flexion. Range of motion measures included: hip internal and external rotation in 90° flexion, hip IR in prone, bent knee fall out and hip abduction in side-lying. Demographic information was collected and the effect on the profiles was analysed using linear mixed models with repeated measures.
  
  
  RESULTS
  Strength values (mean±SD) were: adduction=3.0±0.6Nm/kg, abduction=2.6±0.4Nm/kg, adduction/abduction ratio=1.2±0.2, Squeeze test=3.6±0.8N/kg. Range of motion values: internal rotation in flexion=32±8°, external rotation=38±8°, internal rotation in prone=38±8°, bent knee fall out=13±4.4cm, abduction in side-lying=50±7.3°. Leg dominance had no clinically relevant effect on these profiles. Multivariate analysis demonstrated that age had a minor influence on squeeze strength (-0.03N/kg/year), external rotation (-0.30°/year) and abduction range (-0.19°/year) but past history of injury, and ethnicity did not.
  
  
  CONCLUSIONS
  Normal values are documented for hip strength and range of motion that can be used as reference profiles in the clinical assessment, screening, and management of professional football players. Leg dominance, recent past injury history and ethnicity do not need to be accounted for when using these profiles for comparison purposes.
authors.affiliation: Rehabilitation Department, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar; School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Australia; School of Allied Health, La Trobe University, Victoria, Australia. Electronic address: andrea.mosler@aspetar.com.
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Mosler
authors.affiliation: School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Australia; School of Allied Health, La Trobe University, Victoria, Australia.
authors.forename: Kay M
authors.initials: KM
authors.lastname: Crossley
authors.affiliation: Sports Orthopedic Research Center - Copenhagen (SORC-C), Arthroscopic Center, Department of Orthopedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Denmark.
authors.forename: Kristian
authors.initials: K
authors.lastname: Thorborg
authors.affiliation: Rehabilitation Department, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Rod J
authors.initials: RJ
authors.lastname: Whiteley
authors.affiliation: Sports Groin Pain Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Adam
authors.initials: A
authors.lastname: Weir
authors.affiliation: Sports Groin Pain Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Andreas
authors.initials: A
authors.lastname: Serner
authors.affiliation: Sports Orthopedic Research Center - Copenhagen (SORC-C), Arthroscopic Center, Department of Orthopedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Denmark; Sports Groin Pain Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Per
authors.initials: P
authors.lastname: Hölmich
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005538:Football / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D055815:Young Adult
keywords: Flexibility; Groin; Injury; Soccer; Sports