title: The Effect of Glenohumeral Internal-Rotation Deficit on Functional Rotator-Strength Ratio in Adolescent Overhead Athletes.
abstract: Glenohumeral (GH) internal-rotation deficit (GIRD) and lower eccentric external-rotator (ER) to concentric internal-rotator (IR) strength (ER:IR) ratio have been documented as risk factors for shoulder injuries, but there is no information on whether GIRD has an adverse effect on ER:IR ratio in adolescent overhead athletes.
  
  
  
  The aim of this study was to investigate the effects of GIRD on functional ER:IR ratio of the adolescent overhead athletes.
  
  
  
  Cross-sectional study.
  
  
  
  University research laboratory.
  
  
  
  52 adolescent overhead athletes.
  
  
  
  To determine GIRD, the range of GH IR and ER motion was measured with a digital inclinometer. An isokinetic dynamometer was used to assess eccentric and concentric IR and ER muscle strength of the dominant and nondominant shoulders. One-way ANCOVA where sport type was set as a covariate was used to analyze the difference between athletes with and without GIRD.
  
  
  
  After standardized examinations of all shoulders, the athletes were divided into 2 groups, shoulders with (n = 27) and without GIRD (n = 25). There was a significant difference between groups in functional ER:IR ratio (P < .001). Athletes with GIRD had lower ER:IR ratio (0.56) than athletes without GIRD (0.83).
  
  
  
  As GIRD has an adverse effect on functional ratio of the shoulder-rotator muscles, interventions for adolescent overhead athletes should include improving GH-rotation range of motion.
authors.affiliation: Dept of Physiotherapy and Rehabilitation, Hacettepe University, Ankara, Turkey.
authors.forename: Hande
authors.initials: H
authors.lastname: Guney
authors.forename: Gulcan
authors.initials: G
authors.lastname: Harput
authors.forename: Filiz
authors.initials: F
authors.lastname: Colakoglu
authors.forename: Gul
authors.initials: G
authors.lastname: Baltaci
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular; D012399:Rotation; D012785:Shoulder Joint / Q000503:physiopathology*; D013177:Sports / Q000502:physiology*