Validation of a New Clinical Test: Functional Assessment of System Tension in Overhead Athletes: CSM 2020 American Academy of Sports Physical Therapy Platform Presentation Abstracts

PURPOSE/HYPOTHESIS: Overhead athletes require coordination, control, and mobility of the entire body. This is most evident during the early and late cocking phase of throwing, where the shoulder is in maximal horizontal abduction and external rotation, the trunk is rotated contralaterally, and the ipsilateral hip is extended. Adopting this position allows athletes to optimize myofascial tension allowing more efficient transition from potential to kinetic energy. A staple in rehab for overhead athletes includes high level exercises that incorporate interconnected muscle chains, but interestingly the viscoelastic nature of the muscle chains do not enter into the static assessment process. There is a need to develop a more holistic clinical test for shoulder ROM which reflects the complexity and 3-D nature of throwing. Therefore, the purpose of this study was to determine the reliability and validity of a new clinical test of shoulder ROM (FAST-OA) and to establish normative values in overhead athletes.

NUMBER OF SUBJECTS: Thirty-three healthy collegiate baseball players (mean ± SD age, 19.2 ± 1.2 years; weight, 86.1 ± 7.7 kg; height, 185.5 ± 5.39 cm).

MATERIALS AND METHODS: Participants were assessed for shoulder ROM (internal rotation, IR and external rotation, ER) using (1) traditional supine testing and (2) FAST-OA. During FAST-OA, athletes were positioned in supine, hook-lying with the test shoulder off the plinth. To recreate the late cocking position, the player's pelvis was passively rotated 90° contralateral to the tested arm (secured by strapping the knees around the plinth with a belt), with their back flat to the table. Positioning the test shoulder in 90° of shoulder abduction, a second tester moved the shoulder into maximal passive horizontal abduction, before assessing passive IR and ER ROM, using a bubble inclinometer placed on the ulnar styloid process. Mean differences and paired t tests (P<.01) were used to compare ROM values generated across tests. Intratester reliability of the FAST-OA was excellent (ICC = 0.95–0.97) with MDC (90% CI) ranging from 7° to 9°.

RESULTS: Average shoulder IR values were higher during standard supine testing (dominant, 62.3° ± 12.1°; nondominant, 69.4° ± 12.9°) compared to FAST-OA (dominant, 39.0° ± 9.9°; nondominant, 49.7° ± 12.8°; P<.001). There were even greater differences between test results for ER (standard dominant, 128.2° ± 11.5°; standard nondominant, 115.7° ± 8.6° versus FAST-OA dominant, 77.4° ± 15.0°; FAST-OA nondominant, 66.0° ± 15.0°; P<.001). The total arc of motion was significantly lower based on the FAST-OA compared to the standard test for both dominant (MD, 73.0°; 95% CI: 66.2°, 79.9°; P<.001) and nondominant shoulders (MD, 72.1°; 95% CI: 65.5°, 78.8°; P<.001).

CONCLUSIONS: Collegiate baseball players demonstrated significantly less shoulder ER, IR, and tension arc when compared to standard supine testing.

CLINICAL RELEVANCE: Three dimensional positioning of the body to replicate throwing alters the tensional demands that is distributed across the body, ultimately diminishing end ROM of a baseball players throwing shoulder. While further analysis of the FAST-OA is needed, this accessible and easy to perform clinical test may provide useful information for injury prediction or performance potential in overhead athletes.