Test-retest reliability and discriminative ability of forward, medial and rotational single-leg hop tests

Abstract

Background: Single-leg hop tests are commonly performed in the forward direction to evaluate functional performance. However, athletes move in multiple directions during pivoting sports. The first aim of this study was to examine test-retest reliability of single-leg hop tests in the forward, medial and rotational direction in non-injured athletes. Second, the discriminative ability to detect leg asymmetries with these hop tests in anterior cruciate ligament (ACL) reconstructed athletes was determined. Methods: Sixteen recreational non-injured participants (8 females, 8 males; 22.4±1.9 years) were tested twice (one-week interval) and performed the single hop for distance (SH), triple hop for distance (TH), medial side triple hop for distance (MSTH) and 90° medial rotation hop for distance (MRH). Intraclass correlation coefficients (ICCs), standard errors of measurement (SEM) and smallest detectable differences (SDD) were calculated. Discriminative ability was determined in 32 ACL-reconstructed participants (4 females, 28 males; 24.4±4.6 years; 6 months postoperative) who performed the same hop tests once. Results: The ICCs ranged between 0.93-0.98. The SEM and SDD were respectively 2.6- 4.1% and 7.2-11.3% of the mean hop distance of the group. The proportion (%) of ACLreconstructed participants passing the ≥90% limb symmetry cut-off was 62.5 (SH), 59.4 (TH), 40.6 (MSTH) and 46.9 (MRH). Conclusion: Excellent test-retest reliability of forward, medial and rotational hop tests was found. This allows clinicians to make informed interpretations of changes in hop test distances when retesting athletes. Medial and rotational hop tests are more likely to show limb asymmetries in ACL-reconstructed participants compared to forward hop tests.