title: Modeling and simulating the neuromuscular mechanisms regulating ankle and knee joint stiffness during human locomotion.
abstract: This work presents an electrophysiologically and dynamically consistent musculoskeletal model to predict stiffness in the human ankle and knee joints as derived from the joints constituent biological tissues (i.e., the spanning musculotendon units). The modeling method we propose uses electromyography (EMG) recordings from 13 muscle groups to drive forward dynamic simulations of the human leg in five healthy subjects during overground walking and running. The EMG-driven musculoskeletal model estimates musculotendon and resulting joint stiffness that is consistent with experimental EMG data as well as with the experimental joint moments. This provides a framework that allows for the first time observing 1) the elastic interplay between the knee and ankle joints, 2) the individual muscle contribution to joint stiffness, and 3) the underlying co-contraction strategies. It provides a theoretical description of how stiffness modulates as a function of muscle activation, fiber contraction, and interacting tendon dynamics. Furthermore, it describes how this differs from currently available stiffness definitions, including quasi-stiffness and short-range stiffness. This work offers a theoretical and computational basis for describing and investigating the neuromuscular mechanisms underlying human locomotion.
authors.affiliation: University Medical Center Goettingen, Georg-August University, Goettingen, Germany; massimo.srt@gmail.com.
authors.forename: Massimo
authors.initials: M
authors.lastname: Sartori
authors.affiliation: Department of Management and Engineering, University of Padova, Padova, Italy; and.
authors.forename: Marco
authors.initials: M
authors.lastname: Maculan
authors.affiliation: Centre for Musculoskeletal Research, Griffith University, Queensland, Australia.
authors.forename: Claudio
authors.initials: C
authors.lastname: Pizzolato
authors.affiliation: Department of Management and Engineering, University of Padova, Padova, Italy; and.
authors.forename: Monica
authors.initials: M
authors.lastname: Reggiani
authors.affiliation: University Medical Center Goettingen, Georg-August University, Goettingen, Germany;
authors.forename: Dario
authors.initials: D
authors.lastname: Farina
mesh_terms: D061725:Accelerometry; D000328:Adult; D000843:Ankle Joint / Q000502:physiology; D001696:Biomechanical Phenomena; D004548:Elasticity; D004576:Electromyography; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D012420:Running / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D013710:Tendons / Q000502:physiology; D016138:Walking / Q000502:physiology*
keywords: compliance; electromyography; human leg; neuromusculoskeletal modeling; stiffness