title: Are practice trials required for hop tests?
abstract: Single-legged hop tests are commonly used in clinic and research settings to obtain information on functional performance of the injured leg. When performing these tests, it is typical to provide a few practice trials before performing actual test trials. However, the importance of practice trials and how it affects performance during actual test trials are not known. This study investigated the effect of practice trials on single-leg hop performance using a marker-based kinematic tracking approach in individuals with anterior cruciate ligament (ACL) reconstruction and athletic controls. Thirteen subjects with ACL reconstruction and thirteen uninjured healthy subjects performed the single hop for distance test for both legs. Three practice and five test trials were performed on each leg. Single-leg hop distance scores and hop indices (i.e., side-to-side hop distance ratios) obtained from practice and test trials were compared. There were significant differences in the mean hop distance between practice and test trials (P<0.05) when raw scores were compared, but no differences were observed when comparing the side-to-side distance ratios (P>0.05). There were also significantly high correlations between practice and test trials (P<0.01) and the agreement between practice and test scores was very good (ρc=0.88-0.98). The findings suggest that subjects indeed improve their performance during test trials; however, the improvements had an inconsequential effect on the side-to-side hop distance ratios. Therefore, if the examiner is interested only in side-to-side ratios, then practice trials can be minimized or even avoided to improve efficiency and minimize time and costs associated with additional trials.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Michigan Medical School, Ann Arbor, MI, USA. Electronic address: mouli@umich.edu.
authors.forename: Chandramouli
authors.initials: C
authors.lastname: Krishnan
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D001696:Biomechanical Phenomena; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology*; D008297:Male; D013177:Sports / Q000502:physiology*
keywords: Hop index; Knee surgery; Lower extremity; One leg hop; Performance-based measures