title: Tuning of Muscle Synergies During Walking Along Rectilinear and Curvilinear Trajectories in Humans.
abstract: The aim of this study was to develop a methodology based on muscle synergies to investigate whether rectilinear and curvilinear walking shared the same neuro-motor organization, and how this organization was fine-tuned by the walking condition. Thirteen healthy subjects walked on rectilinear and curvilinear paths. Electromyographic data from thirteen back and lower-limb muscles were acquired, together with kinematic data using inertial sensors. Four macroscopically invariant muscle synergies, extracted through non-negative matrix factorization, proved a shared modular organization across conditions. The fine-tuning of muscle synergies was studied through non-negative matrix reconstruction, applied by fixing muscle weights or activation profiles to those of the rectilinear condition. The activation profiles tended to be recruited for a longer period and with a larger amplitude during curvilinear walking. The muscles of the posterior side of the lower limb were those mainly influenced by the fine-tuning, with the muscles inside the rotation path being more active than the outer muscles. This study shows that rectilinear and curvilinear walking share a unique motor command. However, a fine-tuning in muscle synergies is introduced during curvilinear conditions, adapting the kinematic strategy to the new biomechanical needs.
authors.affiliation: Neuroengineering and Medical Robotics Laboratory, Department of Electronics, Information and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy. noelia.chia@polimi.it.
authors.forename: Noelia
authors.identifier: 0000-0002-1297-254X
authors.initials: N
authors.lastname: Chia Bejarano
authors.affiliation: Neuroengineering and Medical Robotics Laboratory, Department of Electronics, Information and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pedrocchi
authors.affiliation: Posture and Movement Laboratory, Division of Physical Medicine and Rehabilitation, Scientific Institute of Veruno, Fondazione Salvatore Maugeri (IRCCS), Veruno, Novara, Italy.|Department of Translational Medicine, University of Eastern Piedmont, Novara, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Nardone
authors.affiliation: Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy.|Centro Studi Attività Motorie (CSAM), Scientific Institute of Pavia, Fondazione Salvatore Maugeri (IRCCS), Pavia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Schieppati
authors.affiliation: Neuroengineering and Medical Robotics Laboratory, Department of Electronics, Information and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy.|Ab.Acus, Milan, Italy.
authors.forename: Walter
authors.initials: W
authors.lastname: Baccinelli
authors.affiliation: Department of Public Health, Clinical and Molecular Medicine, University of Cagliari, Cagliari, Italy.|Physical Medicine and Rehabilitation Unit, Scientific Institute of Lissone, Fondazione Salvatore Maugeri (IRCCS), Lissone, Monza Brianza, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Monticone
authors.affiliation: Neuroengineering and Medical Robotics Laboratory, Department of Electronics, Information and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ferrigno
authors.affiliation: Neuroengineering and Medical Robotics Laboratory, Department of Electronics, Information and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Ferrante
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology*; D016138:Walking / Q000502:physiology*
keywords: Curvilinear walking; Electromyography; Locomotion; Muscle synergies