Synergy in motion: Exploring the similarity and variability of muscle synergy patterns in healthy individuals.

Background: Recent studies suggest that muscle synergy patterns can be a guide for diagnosis and rehabilitation.

Research Question: Does human's lower limb synergy pattern significantly change with changes in walking speed? Are there large differences in synergy patterns among different healthy individuals?

Methods: 22 healthy subjects from an open-source datasets were included. Non-negative matrix factorization was applied to identify the module composition of surface electromyography(sEMG) data, and the similarity index was adopted to quantify the overall similarity between synergy patterns.

Results: Results demonstrated that healthy individuals have their own intrinsic muscle recruitment and coordination characteristics for locomotion at various speeds, additionally, their synergy patterns exhibit predictability under speed variations.

Significance: This study develop reference synergy patterns for the lower limbs across 28 different walking speeds. The developed synergy patterns and the above findings may guide the study of gait synergy in rehabilitation and assistance.