title: Normative values of agonist-antagonist shoulder strength ratios of adults aged 20 to 78 years.
abstract: OBJECTIVE
  To determine normative values for isometric flexion/extension, abduction/adduction, and external/internal rotation strength ratios about the shoulder and to determine if these ratios are affected by age or gender.
  
  
  METHODS
  A cross-sectional study of 120 healthy volunteers (60 men, 60 women) aged 20 to 78 years.
  
  
  METHODS
  Orthopedic research laboratory.
  
  
  METHODS
  Flexion and extension strengths were measured isometrically using a Cybex II dynamometer at arm flexion angles of 30 degrees, 60 degrees, and 90 degrees. Abduction and adduction strengths were measured at 30 degrees, 60 degrees, and 90 degrees abduction. Internal and external rotation strengths were measured (1) with the arm abducted 15 degrees and neutral external/internal rotation and (2) with the arm abducted 90 degrees and externally rotated 30 degrees above the transverse plane.
  
  
  METHODS
  Isometric strength ratios for flexion/extension, abduction/adduction, and external/internal rotation.
  
  
  RESULTS
  No statistically significant differences in agonist/antagonist strength ratios were found between dominant and nondominant sides or between genders. Age was associated with changes in strength ratios for measurements taken with the arm flexed or abducted 90 degrees. Posture was found to affect strength ratios.
  
  
  CONCLUSIONS
  These data can serve as a normative reference for clinical use.
authors.affiliation: Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic and Mayo Foundation, Rochester, MN 55905, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Hughes
authors.forename: M E
authors.initials: ME
authors.lastname: Johnson
authors.forename: S W
authors.initials: SW
authors.lastname: O'Driscoll
authors.forename: K N
authors.initials: KN
authors.lastname: An
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012399:Rotation; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D012785:Shoulder Joint / Q000502:physiology*