![]() ![]() In healthy subjects, the mathematical weight coefficients assigned to the muscles to model each synergy do not change significantly when walking speed changes. When VAF1 is high, one synergy can explain most of the variance in muscle activation, which indicates a reduction in the complexity of motor control during the task. The VAF by one synergy (VAF1) is a summarized measure of synergy complexity. For the synergy analysis, evaluating the "total variance accounted for" (VAF) by a given number of synergies allows to quantify the complexity of an individual’s muscle activation pattern. ![]() In healthy subjects, muscle activity during comfortable walking is composed of four independent muscle synergies: hip and knee extensors (module 1), ankle plantar flexors (module 2), hip flexors and ankle dorsiflexors (module 3), and knee flexors (module 4). Therefore, the abnormal patterns of lower-limb muscle activity observed during various phases of the stance or swing phase are considered to influence the differences in asymmetry characteristics. Gait asymmetry is related to impaired timing of lower-limb muscle activity. Many post-stroke patients are observed to have asymmetric flexion or extension angles of the lower-limb during comfortable walking however, the characteristics of this asymmetry differ across individual patients, who may exhibit either a reduced flexion or extension angle of the paretic lower-limb. Recent studies suggest that the level of asymmetry is more important than deficits in walking speed for understanding the degree of walking deficit and the compensatory mechanisms in post-stroke patients. Gait asymmetry is a characteristic feature of stroke-related walking disorder and is associated with increased the risk of falls. And data requests may also be directed to corresponding author Naomichi Mizuta (email: The authors received no specific funding for this work.Ĭompeting interests: The authors have declared that no competing interests exist. Data requests may be directed to the Kio University (email: telephone: 01 fax: 00). This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: Data cannot be shared publicity because the participants did not consent for public sharing. Received: AugAccepted: JanuPublished: February 4, 2022Ĭopyright: © 2022 Mizuta et al. PLoS ONE 17(2):Įditor: Kei Masani, Toronto Rehabilitation Institute - UHN, CANADA (2022) Merged swing-muscle synergies and their relation to walking characteristics in subacute post-stroke patients: An observational study. Rehabilitation with increased lower-limb flexion may be effective for the training of patients with merging of modules 3 and 4 in comfortable walking.Ĭitation: Mizuta N, Hasui N, Nishi Y, Higa Y, Matsunaga A, Deguchi J, et al. This subtype classification of walking impairments based on the merging pattern of the muscle synergies could be useful for the selection of a rehabilitation strategy according to the individual’s particular neurological condition. A more complex muscle synergy was observed only in subtype 3 in the p-long condition versus cws ( p = 0.036). In the cws condition, the lower-limb flexion angle was reduced in subtype 3, and the lower-limb extension angle was decreased in subtype 1. We identified three merging subtypes: module 1 with module 2 (subtype 1), module 1 with module 4 (subtype 2), and module 3 with module 4 (subtype 3). Subtype classification was based on the merging pattern of the muscle synergies, and we examined the effect of different lower-limb angles on the muscle synergies. Lower-limb flexion and extension angles and the electromyogram were measured during walking. Forty-one participants were assessed under three conditions: cws, long stepping on the paretic side (p-long), and long stepping on the non-paretic side (np-long). We also examined the effect of experimental lower-limb angle modulation on the muscle synergy patterns of walking in each subtype. ![]() ![]() This study aimed to determine the muscle-synergy merging subtypes of post-stroke during comfortable walking speed (cws). However, post-stroke individuals with a merging pattern of module 3 (hip flexor and ankle dorsiflexor) and module 4, which is the swing-muscle synergy, have not been reported. In some patients, the muscle synergy termed module 1 (hip/knee extensors) is merged with module 2 (ankle plantar flexors), and in other cases, module 1 is merged with module 4 (knee flexors). In post-stroke patients, muscle synergy (the coordination of motor modules during walking) is impaired. ![]()
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