Isometric strength of the shoulder internal and external rotator muscles in racquet sports players: Systematic Review with Meta-analysis

Purpose/Background: In the shoulder, external and internal rotators’ strength balance is needed to guarantee a good stabilization. Racquet players are subject to shoulder injuries because of the serve movement’s repetitive nature developing muscle adaptations and imbalances. The main goal of this systematic review is to collect data from previous studies about the shoulder’s internal and external rotation isometric strength in racquet sport players. Methods: A systematic review was conducted to identify relevant studies in the databases PubMed and ScienceDirect. The extracted data included study design, participants’ profiles and internal/external rotators’ isometric strength. The standardized mean differences of internal and external rotators strength between the dominant and non-dominant side were calculated and a meta-analysis was performed. Results: Six studies were included in this review. The pooled data showed higher significant internal and external rotation isometric strength in the dominant side compared to the non-dominant side and higher significant internal rotators’ isometric strength values in both sides compared to the external rotators. Conclusion: The results of this review confirm that racquet sports players have deficit in external rotators’ strength compared to the internal rotators in both sides. To reduce this imbalance, programs targeting the external rotators are necessary.