A study of the reproducibility and reliability of the musculo-articular stiffness of the ankle joint

Abstract The objective of this work was to evaluate the reproducibility, reliability and usefulness of the musculo-articular stiffness (MAS) of the ankle joint, measuring it by the free vibration technique. Seventeen (nine males and eight females) healthy university students were included in the study. Force ( f ), MAS ( k ) and unitary MAS ( k u ) (defined as the ratio between the value of stiffness k obtained in the test (absolute terms) and the value of force ( f )) were obtained. A test-retest protocol was designed and performed on the same day to determine the short-term reproducibility of f , k and k u . Short-term reproducibility of k and k u on 1 day in absolute terms ( k and k u in absol u te terms ( k and k u (1 day and 1 week) were considered. The Minimal Difference needed to be considered “real” (MD) for k u ≅ 3.5% (1 day); k u ≅ 8.5% (1 wee k ) ( p k u than k . Therefore, the unitary stiffness ( k u ) proven to be representative of the mechanical response of the ankle joint obtained by free vibration techniques, which allows comparison between different subjects.