Upper and Lower Body Strength Asymmetries and Shoulder Rotation Strength Ratio in Youth Tennis Players Using Isokinetic Testing

Abstract

Background: This study examined upper and lower body (interlimb) strength asymmetries and shoulder rotation strength ratios in youth tennis players using isokinetic testing. Methods: Seventeen players (male = 10, age: 15.60 ± 1.65 years; female = 7, age: 15.57 ± 1.51 years) from the same tennis academy volunteered to participate in the study. Handgrip strength, internal and external rotators’ torque and the torque produced by the quadriceps and hamstring muscles were evaluated. Results: Significant upper limb asymmetries were indicated in strength between the dominant and non-dominant arms in several areas: handgrip strength (p = 0.01), internal and external rotators’ torque at 60°/s (p = 0.01) and 180°/s (p = 0.01) and the ratios of external and internal rotation (ER:IR ratios) (p = 0.01). Lower body torque assessment did not reveal any asymmetries. Conclusion: Our findings highlight that significant interlimb asymmetries are evident in youth tennis players’ upper body but not the lower body. These upper limb asymmetries develop early, making it essential for coaches and athletes to recognize them for injury prevention and performance enhancement. A focus should be placed on adding exercises that strengthen the external rotators of the dominant arm as well as the internal and external rotators of the non-dominant arm.