Influence of reduced passive ankle dorsiflexion range of motion on lower limb kinetics and stiffness during gait

Background: The ankle dorsiflexion range of motion (ADF-ROM) during single support phase allows elastic energy storage in the calcaneal tendon, contributing to advance the body forward. Reduced ADF-ROM may influence lower limb kinetics and stiffness. Research question: What is the influence of reduced passive ADF-ROM on lower limb internal moments and stiffness during gait? Methods: Thirty-two participants, classified into two groups according to passive ADF-ROM (smaller than 10 and greater than 15), were submitted to gait assessment at self-selected speed with a force platform and a three-dimensional motion analysis system. Statistical parametrical mapping (SPM) analyses were used to compare the lower limbs' internal moments between groups. Independent t-tests analyzed the differences between groups on lower limb stiffness during gait. Results: The lower ADF-ROM group had greater knee flexor moment (terminal stance and push-off), greater ankle abductor (i.e., shank internal rotator) moment in terminal stance and greater knee internal rotator moment in mid to terminal stance. The lower ADF-ROM group also had higher lower limb stiffness during gait. Significance: Individuals with reduced passive ADF-ROM had greater lower limb stiffness and adopted a gait pattern with increased knee and ankle moments, suggesting increased loading at these joints.