Relationship between gait quality measures and modular neuromuscular control parameters in chronic post-stroke individuals

Abstract

Background Recent evidence suggests that disinhibition and/or hyperexcitation of the brainstem descending pathways and intraspinal motor network diffuse spastic synergistic activation patterns after stroke. This results in simplified or merged muscle sets (i.e., muscle modules or synergies) compared to non-impaired individuals and this leads to poor walking performance. However, the relations of how these neuromuscular deficits influence gait quality (e.g., symmetry or natural walking patterns) are still unclear. The objective of this exploratory study was to investigate the relations of modular neuromuscular framework and gait quality measures in chronic stroke individuals. Methods Sixteen chronic post-stroke individuals participated in this study. Full lower body three-dimensional kinematics and electromyography (EMG) were concurrently measured during overground walking at a comfortable speed. We first examined changes in gait quality measures across the number of muscle modules using linear regression model. Then, a stepwise multiple regression was used to investigate the optimal combination of the neuromuscular parameters that associates with gait quality measures. Results We observed that subjects who had a lower number of muscle modules revealed reduced function (i.e., speed) and greater asymmetry in the kinematic parameters including limb length, footpath area, knee flexion/extension, and hip abduction/adduction (all p < 0.05). We also found that the combination of input variables from the modular neuromuscular control framework significantly associated with gait quality measures (average $${R}^{2}=42.5\mathrm{\%}$$ R 2 = 42.5 % ). Those variables included variability accounted for ($$VAF$$ VAF ) information from the muscle modules and area under the EMG envelope curves of the quadriceps (i.e., rectus femoris and vastus lateralis) and tibialis anterior muscles. Conclusions The results suggest that there exists a significant correlation between the neuromuscular control framework and the gait quality measures. This study helps to understand the underlying mechanism of disturbances in gait quality and provides insight for a more comprehensive outcome measure to assess gait impairment after stroke.

Soft robotic exosuit augmented high intensity gait training on stroke survivors: a pilot study

“…Another limitation of this work included lack of neuromuscular analysis of participants’ walking using electromyography (EMG). However, we speculate that the soft exosuit intervention would have positively influenced the neuromuscular properties of our participants given that there is a strong relationship between gait quality measures and neuromuscular control parameters [ 41 ]. Future work incorporating additional measurements including three dimensional joint kinematics and EMG analysis would provide more comprehensive characterization of therapeutic effect on gait recovery with the intervention.…”

Association Between Temporal Asymmetry and Muscle Synergy During Walking With Rhythmic Auditory Cueing in Survivors of Stroke Living With Impairments

“… 7 , 8 In contrast, the independent activation of muscle synergy is impaired in many survivors of stroke, and consequently, the muscle synergies are merged (monotonic activation of muscle synergy). 8 , 10 , 11 , 12 This monotonous muscle synergy is associated with asymmetry in the kinematics and spatial parameters of walking in survivors of stroke in some previous studies 8 , 11 , 12 , 13 ; however, the relationship between temporal asymmetry of walking and complexity of muscle synergy has not been demonstrated. Because temporal asymmetry while walking in survivors of stroke is associated with impaired timing of lower limb muscle activity, 14 it may be associated with muscle synergy, which controls the lower limb muscle activity during walking.…”

Merged swing-muscle synergies and their relation to walking characteristics in subacute post-stroke patients: An observational study

“…Although previous studies have assessed the complexity of muscle synergy by the number of muscle synergies [13,15,23,49], we used VAF1 as a measure of the complexity of muscle synergy. Because the number of muscle synergies was determined based on the value of VAF [12][13][14][15], the number of muscle synergies and VAF1 are essentially similar. However, because the threshold for determining the number of muscle synergies is an arbitrary value, VAF1 is likely to be more sensitive in capturing the complexity of muscle synergies than the number of muscle synergies [12,[16][17][18][19][20].…”

“…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) [11]. 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 [12][13][14][15][16][17][18][19][20]. The VAF by one synergy (VAF1) is a summarized measure of synergy complexity.…”

“…In healthy subjects, the mathematical weight coefficients assigned to the muscles to model each synergy do not change significantly when walking speed changes [21,22]. However, many chronic post-stroke patients show a merging of these muscle synergies during comfortable walking [13][14][15][23][24][25]. Walking subtypes have been reported to show a merging of module 1 with module 2 or module 1 with module 4 in chronic post-stroke patients [13,26].…”