Does total rotation range of motion asymmetry have an effect on shoulder isometric muscle strength in young swimmers

Objective: The total rotational range of motion (TRROM) difference in right-left side shoulder glenohumeral joint and muscle strength imbalance  in the dominant-nondominant side have been reported to be associated with injury in swimmers. The purpose of this study was to investigate  the shoulder isometric muscle strength of young swimmers with and without TRROM asymmetry. Methods: Assessments of passive TRROM were measured with a goniometer. Hand-held dynamometry was used for the shoulder isometric  muscle strength measurements in young swimmers. Thirty-two female swimmers (age: 11.1±1.5 years; body weight: 39.8±9.6 kg) and 42 male  swimmers (age: 10.9±1.6 years; body weight 38.1±8.3 kg) were divided into two groups according to TRROM asymmetry in glenohumeral joint. Results: Isometric strength of shoulder muscles (flexion , extension , external rotation (ER) , internal rotation (IR) , Flexion: Extension and  External rotation: Internal rotation) were similar between the groups with TRROM asymmetry (n=30) and without TRROM asymmetry (n=44) in  both dominant and non-dominant sides (p>0.05). Additionally, while external rotation: internal rotation of dominant side was greater in femal   (p=0.04), other isometric muscle strength and ratio were similar in both gender (p>0.05). Conclusions: TRROM asymmetry is one of the many factors affecting muscle strength in overhead sports (basketball, volleyball) but it is not  effective in these ages range in the swimming.