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This assessment focuses specifically on shoulder external rotation at 90 degrees. This protocol is utilised as part of an assessment of the muscles responsible for controlling and stabilising the shoulder girdle. Deficits in control, strength and endurance of these muscles have been associated with shoulder and elbow injuries in overhead / throwing sports.
Practitioners typically use this protocol as part of a broader musculoskeletal screening or return-to-play assessment.
The shoulder is particularly vulnerable to injury in overhead sports such as baseball, tennis, handball, and volleyball, primarily due to the high mechanical loads and repetitive stresses it endures. According to Prevention of Shoulder Injuries in Overhead Athletes: A Science-Based Approach by Cools et al. (2015), the complex biomechanics involved in overhead movements place substantial demands on the glenohumeral joint and surrounding musculature. The study emphasises that imbalances in shoulder rotational strength, limited range of motion, and poor scapular control are key modifiable risk factors contributing to shoulder injuries in these athletes. Implementing targeted assessment and training strategies, particularly those focusing on external rotation strength at 90 degrees abduction, can play a critical role in injury prevention and performance optimisation for overhead athletes.
The study by Vargas et al. (2020) underscores the importance of assessing shoulder external rotation strength in the 90°/90° position, as it closely replicates the demands of overhead sports. By evaluating external and internal rotator strength with the shoulder abducted to 90 degrees and the elbow flexed to 90 degrees, the researchers provided a testing position that mirrors the biomechanics of throwing. Their findings support the use of this position in strength assessments for overhead athletes, reinforcing its relevance for injury prevention and performance monitoring protocols.
It is also important to note that the method used to measure and monitor shoulder external rotation strength is just as important as the strength itself, significantly influencing the reliability of the data collected . Although handheld dynamometers are typically compact and portable, they can offer a number of different limitations, such as inconsistent stabilisation and variability in the application of resistance. However, fixed frame dynamometry systems such as the KT360 provide a stable, repeatable testing environment that minimises human error.
If you would like to delve deeper into our suite of protocols and explore how they can benefit your organisation, please contact our VP of Customer Success at james.evans@kangatech.com.
