title: Are professional handball players at risk for developing a glenohumeral internal rotation deficit in their dominant arm?
abstract: Overhead athletes, such as baseball players, have been shown to have adaptive changes in the shoulder range of motion (ROM) of their dominant arm. Professional handball players are a unique subtype of overhead athletes with very different demands from baseball players. The aim of this study was to determine if professional handball players demonstrate differences in shoulder ROM between their dominant and non-dominant arm and try to relate them with new variables.
  
  
  
  Fifty professional male handball players were included and completed a questionnaire regarding age at which they started to play, number of hours they practice a week, field position and arm dominance. ROM measurements were performed including forward flexion (FF), external rotation with the shoulder in abduction (ABER) and with adducted arm (ADER) and internal rotation with shoulder in abduction (IR). Statistical analysis was performed to determine differences in ROM between the dominant and non-dominant shoulder and if there is a relationship between these differences and shoulder load or field position.
  
  
  
  The dominant arm showed decreased internal rotation (47 vs. 56 degrees, p < 0.001) and increased external rotation both with the arm abducted (99 vs. 88 degrees, p < 0.001) and at the side (62 vs 57 degrees, p = 0.001). This was not correlated with shoulder load for any movement (FF, p = 0.980; ABER, p = 0.741; ADER, p = 0.803; IR, p = 0.085) but was dependent on field position with first line players showing the highest internal rotation deficit (13 degrees vs. 6-7 degrees in the other field positions, p = 0.013).
  
  
  
  This study showed that professional male handball players with a first line position have a significant risk for developing a glenohumeral internal rotation deficit, similar to the phenomenon seen in baseball pitchers.
authors.affiliation: a Faculty of Medicine , University of Porto , Porto , Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Seabra
authors.affiliation: c Kerlan Jobe Orthopaedic Clinic , Los Angeles , CA.
authors.forename: Carola F
authors.initials: CF
authors.lastname: Van Eck
authors.affiliation: b Primary Healthcare Unit 'Saúde em Família' , Maia , Portugal.
authors.forename: Márcia
authors.initials: M
authors.lastname: Sá
authors.affiliation: a Faculty of Medicine , University of Porto , Porto , Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Torres
mesh_terms: D000328:Adult; D001132:Arm; D056352:Athletes; D001265:Athletic Injuries / Q000209:etiology*; D001484:Baseball; D012090:Cumulative Trauma Disorders / Q000209:etiology*; D007839:Functional Laterality; D006225:Hand; D006801:Humans; D008297:Male; D016059:Range of Motion, Articular; D012306:Risk; D012399:Rotation; D012782:Shoulder; D000070599:Shoulder Injuries; D013177:Sports; D055815:Young Adult
keywords: Shoulder; field position; hand dominance; handball; professional sport; range of motion