Kalo K, Vogt L, Sieland J, et al. - The present study was conducted to assess age, gender, specific training data (i.e. training volume, years of tennis practice, years of competitive play), and upper extremity injuries on glenohumeral internal rotation deficit (GIRD) in youth competitive tennis athletes. Researchers designed a cross-sectional retrospective study design to include Youth tennis players (n = 27, 12.6 ± 1.80 yrs., 18 male) belonging to an elite tennis squad. In youth tennis athletes, injury and training history but not age or training volume may impact on glenohumeral internal rotation deficit. The findings revealed that GIRD in the dominant side in youth tennis players is progressive with increasing years of tennis practice and independent of years of practice associated with the history of injuries. The outcomes of this research demonstrated that early detection of reduced glenohumeral RoM (specifically IR), as well as injury prevention training programs, may be beneficial to decrease GIRD and its negative consequences.