Psychometric Properties of the Athletic Shoulder Test in Adolescent Tennis Players

Background/Objectives: The Athletic Shoulder Test (ASH) has been described as one of the most promising upper-extremity tests to assess performance in overhead athletes. Its high reliability rates, short testing period, and applicability in any environment with portable and cheap equipment have been highlighted as some of the advantages of the test. However, it has yet to be evaluated in a non-adult athletic population. Therefore, the aim of this study was to investigate the ASH test's psychometric properties in a sample of young tennis players. Methods: A total of 33 adolescent tennis players were evaluated among two sessions with a week interval. Intra-rater, inter-rater, and test-retest reliability were investigated. Additionally, possible correlations with measures of rotational shoulder strength and upper-extremity performance were examined. Two novice physiotherapists performed all the measurements following appropriate training. Results: The relative reliability scores, as calculated by intraclass correlation coefficient (ICC) indices, were found to be excellent (ICC = 0.924-0.988). Standard error of measurement and minimal detectable change scores have been estimated per position (SEM = 2.74-7.06 N, MDC = 7.55-19.42N). Test-retest reliability provided slightly higher SEM and MDC scores on average (SEM = 3.33-6.47, MDC = 9.32-18.04) than intra-rater and inter-rater reliability. Associations between ASH and the two tests were found to be moderate to strong (r = 0.584-0.856), with the dominant arm providing higher correlation scores (r = 0.605-0.856) than the non-dominant one (r = 0.584-0.823). Absolute values were collected and are provided for all three upper-limb tests; normalized values were calculated for ASH and rotational strength and peak torque only for the ASH measurements. Conclusions: The excellent reliability rates establish the ASH test as a highly recommended testing protocol for adolescent tennis players.