title: Summary of Human Ankle Mechanical Impedance During Walking.
abstract: The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia. The purpose of this short communication is to unify the results of the first two studies measuring ankle mechanical impedance in the sagittal plane during walking, where each study investigated differing regions of the gait cycle. Rouseet al.measured ankle impedance from late loading response to terminal stance, where Leeet al.quantified ankle impedance from pre-swing to early loading response. While stiffness component of impedance increases significantly as the stance phase of walking progressed, the change in damping during the gait cycle is much less than the changes observed in stiffness. In addition, both stiffness and damping remained low during the swing phase of walking. Future work will focus on quantifying impedance during the "push off" region of stance phase, as well as measurement of these properties in the coronal plane.
authors.affiliation: School for Engineering of Matter, Transport, and Energy Arizona State University Tempe AZ 85287 USA.
authors.forename: Hyunglae
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering and Department of Biomedical EngineeringNorthwestern UniversityEvanstonIL60208USA; Department of Physical Medicine and RehabilitationNorthwestern UniversityChicagoIL60611USA; Center for Bionic MedicineRehabilitation Institute of ChicagoChicagoIL60611USA.
authors.forename: Elliott J
authors.initials: EJ
authors.lastname: Rouse
authors.affiliation: Department of Mechanical EngineeringMassachusetts Institute of TechnologyCambridgeMA02139USA; Department of NeurologyUniversity of Maryland School of MedicineBaltimoreMD21201USA; Department of Rehabilitation Medicine ISchool of MedicineFujita Health UniversityNagoyaJapan; Institute of NeuroscienceNewcastle UniversityNewcastle Upon TyneU.K.; Department of Mechanical Science and BioengineeringOsaka UniversityOsakaJapan.
authors.forename: Hermano Igo
authors.initials: HI
authors.lastname: Krebs
keywords: Human ankle; ankle damping; ankle impedance; ankle stiffness