Assessing position sense in motion: Reliability of a dynamic joint position reproduction test

BACKGROUND: One of the most common ways to assess the sense of position is the Joint Position Reproduction (JPR) task, where a person reproduces a memorized joint position. While useful, this method is limited because it focuses on static positions and does not fully reflect the dynamic nature of real movements. NEW METHODS: This study investigated the test-retest reliability of the Dynamic JPR (D-JPR) task, during Concentric and Eccentric muscle contractions. Twenty-eight participants were recruited and received a tactile stimulus indicating the position cue at Initial (INI), Intermediate (INT), and Final (FIN) phases of movements, during either the concentric or eccentric phases. After the movement, they replicated the position where they received the stimulus. Angular error (AE) was analysed. Intraclass Correlation Coefficient (ICC) was used to assess relative reliability; Standard Error of Measurement (SEM) and Bias were used to assess absolute reliability. RESULTS: The relative reliability was good in most conditions (ICC > 0.75), with moderate values only for some phases. Absolute reliability showed a variable SEM between conditions, with higher values in the initial eccentric contraction phase. The Bland-Altman plots showed low bias between test and retest. The best reliability was obtained by averaging movement phases and muscle contractions (ICC = 0.89, SEM = 1.35°, Bias = 0.91°). COMPARISON WITH EXISTING METHODS: The D-JPR provides a more suitable way to assess joint position sense during movement compared to existing methods. CONCLUSION: The D-JPR task is a reliable method for assessing joint position sense in dynamic conditions.