Do Vertical Stiffness or Dynamic Joint Stiffness Have Footedness-related Differences?

Abstract

Aims: Unilateral hopping (UH) is one of the common tests for footedness assessment. Inter-limb differences between vertical stiffness (KVERT), ankle dynamic joint stiffness (ADJS) and knee dynamic joint stiffness (KDJS) are expected to exist between the dominant and non-dominant limb. Thus the objective of the present study is to verify those differences, denoting KVERT, ADJS and KDJS as indicators of footedness. Study Design: Comparative study. Place and Duration of Study: MovLab/ CICANT/ Universidade Lusófona de Humanidades e Tecnologias, between November 2013 and June 2014. Methodology: A total of 31 participants (20 female and 11 male) presenting different footedness (right and left) were assessed. Using a 3D motion capture system and a force platform, 10 seconds of UH (for each side) were recorded. Synchronised ankle and knee sagittal moment of force-angular position were used to calculate ADJS and KDJS for the support phase of all hops recorded by participant, divided into two sub-phases: controlled dorsiflexion (CDF) and powered plantar flexion (PPF). The same criteria was used to analyse the synchronised vertical component of ground reaction force (GRFz)-centre of mass (CoM) displacement used for KVERT computation. A paired samples t-test was used to assess inter-limb differences. Results: No significant differences were found between the dominant and non-dominant limb with the exception of the ADJS in the PPF stance sub-phase (p<0.05). Conclusion: Footedness does not seem to influence KVERT or KDJS during a hopping task, whereas ADJS presents differences in PPF stance sub-phase.