Modeling and simulating the neuromuscular mechanisms regulating ankle and knee joint stiffness during human locomotion

Massimo Sartori*, Marco Maculan, Claudio Pizzolato, Monica Reggiani, Dario Farina

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

92 Citations (Scopus)
26 Downloads (Pure)


This work presents an electrophysi-ologically 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 over ground 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.

Original languageEnglish
Pages (from-to)2509-2527
Number of pages19
JournalJournal of neurophysiology
Issue number4
Publication statusPublished - 23 Oct 2015


  • Compliance
  • Electromyography
  • Human leg
  • Neuromusculoskeletal modeling
  • Stiffness
  • n/a OA procedure


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