On footedness and ankle’s Dynamic Joint Stiffness relation

Our earlier reports suggest no dynamic joint stiffness (DJS) inter-limb differences related to footedness. A different approach to our data was used in this study: first define ankle DJS, then look for inter-limb differences and finally correlate them with the subject’s perceived footedness. Methods: 31 subjects (20 females, 11 males) were assessed for ankle DJS during the stance phase of gait, unilateral triple-jump for distance (TSU) and single-leg hopping (Hop). DJS was obtained by linear models at three stance sub-phases (controlled plantar flexion (CPF); controlled dorsiflexion (CDF); power plantar flexion (PPF)). Footedness assessed by the Lateral Preference Inventory (LPI). Results: Paired samples t-test showed statistical inter-limb differences in ankle DJS at PPF on gait (p< 0.01) and Hop (p< 0.05) tasks. No footedness-DJS correlation was found with exception of the TSU PPF (Pearson’s p<0.05). Descriptive analysis shows that in gait, 55% of the subjects maintained the same stiffer ankle between the CPF and the CDF, 45% keep the same stiffer ankle between CDF and PPF, and only 19% keep the same stiffer ankle along all stance. In TSU and Hop, only 48% and 74%, respectively, keep the same stiffer ankle between CDF and PPF. Conclusion: This approach increased our earlier findings of footedness-DJS correlation, but the results are still low. The variability of DJS along the stance sub-phases between tasks needs more attention. Hop task cold be more adequate for footedness assessment due to a more consistent DJS behaviour along the stance.