![]() Understanding how users adapt their movement and neuromuscular control in response to external assistance is important to inform the design of these devices. How do muscle activations and synergies change when an individual wears an ankle exoskeleton during gait?Ībstract: Exoskeletons have the potential to assist and augment human performance. Journal article in Journal of Biomechanics: KM Steele, RW Jackson, BR Shuman, SH Collins (2017) “Muscle recruitment and coordination with an ankle exoskeleton.” Journal of Biomechanics These results demonstrate that EMG signal processing methods impact outputs of synergy analysis and z-score based measures can assist in reporting and comparing results across studies and clinical centers. Synergy weights and activations were impacted less than tVAF by LP filter choice and unit variance normalization. ![]() Unit variance scaling caused comparatively small changes in tVAF. Normalizing tVAF to a z-score (e.g., dynamic motor control index during walking, walk-DMC) reduced sensitivity to LP cutoff. ![]() This change in tVAF can alter the number of synergies selected for further analyses. We found that the total variance accounted for (tVAF) by a given number of synergies was sensitive to LP filter choice and decreased in both TD and CP groups with increasing LP cutoff frequency (e.g., 9.3 percentage points change for one synergy between 4 and 40 Hz). We also evaluated the impact of normalizing EMG amplitude by unit variance. We applied LP filters to the EMG data with cutoff frequencies ranging from 4 to 40 Hz (reflecting the range reported in prior synergy research). We evaluated EMG data collected during barefoot walking from five muscles of 113 children with cerebral palsy (CP) and 73 typically-developing (TD) children. We evaluated the impacts of two common processing steps for synergy analyses: low pass (LP) filtering and unit variance scaling. The aim of this study was to evaluate how EMG signal processing impacts synergy outputs during gait. When considering potential clinical applications of synergies, understanding how EMG data processing impacts results and clinical interpretation is important. Research has shown that fewer synergies are required to describe EMG data of individuals with neurologic impairments. ![]() Journal article in Frontiers in Computational Neuroscience:įiltering parameters impact the results from muscle synergy analyses.Ī bstract: Muscle synergies calculated from electromyography (EMG) data identify weighted groups of muscles activated together during functional tasks. ![]()
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