Abstract: Stroke patients experience varying degrees of upper limb functional impairment. Although bilateral arm training can help stroke patients recover movement after stroke, little is known about the way in which the brain and muscles work together during this type of training. To address this, we conducted a cross-sectional study at The Seventh Affiliated Hospital, Sun Yat-sen University in China, where we observed the connection between brain and muscle activity during bilateral upper limb training in 21 stroke patients and 17 healthy controls. We used functional near-infrared spectroscopy and surface  electromyography to measure changes in cerebral cortex oxygenation and upper limb muscle contraction signals, respectively. The results showed that, compared with the healthy control group, stroke patients had reduced functional connectivity and more irregular muscle activity in the affected flexor muscle during bilateral upper limb training. Moreover, we found a significant correlation between the surface electromyographic signal characteristics of upper limb muscles and cerebral oxygenation indicators of multiple brain regions in stroke patients. These findings indicate that bilateral upper limb training is an effective rehabilitation method that improves upper limb motor function in stroke patients by promoting brain functional connectivity and improving muscle activity patterns.

Key words: bilateral arm training, coordination, entropy, functional connectivity, hemiparesis, interaction, near-infrared spectroscopy, neuroplasticity, stroke, surface electromyography