Tai Ji for stroke rehabilitation: a randomized controlled trial on improving upper limb function and cortico-muscular coupling in stroke patients

OBJECTIVE: This study investigates the impact of integrating Tai Ji into rehabilitation on sensorimotor cortex and upper limb muscle activation in stroke patients, addressing the current lack of research on its underlying mechanisms, despite its well-documented benefits for upper limb function. METHODS: Eighty-four stroke patients were randomized into a Tai Ji group (n = 42) and a control group (n = 42). Additionally, a healthy reference group (n=[30]) was recruited to establish normative baseline synergy patterns. Both groups received conventional rehabilitation, while the Tai Ji group practiced 8-Form Tai Ji for 60 min, five times a week, over four weeks. Functional outcomes were assessed using the Fugl-Meyer Assessment for the Upper Extremity (FMA-UE) and the Modified Barthel Index (MBI). Neural and muscular activities were evaluated by analyzing the coherence and directional connectivity of synchronous electroencephalography and surface electromyography (EEG-sEMG) using Partial Transfer Entropy (PTE), which quantifies information flow between the sensorimotor cortex and muscles. RESULTS: After 4 weeks, the Tai Ji group demonstrated significantly greater improvements in upper-limb motor function (FMA-UE total score and subscales) and activities of daily living (MBI) than the control group (P < 0.05). Neurophysiological analysis revealed that Tai Ji training enhanced descending functional connectivity from the contralateral motor cortex to key upper limb muscles and facilitated ascending connectivity from muscles to the sensory cortex (P < 0.05), changes associated with a shift toward normalization of pathological muscle synergy patterns. Furthermore, exploratory analyses indicated trend-level associations between improvements in specific motor functions (e.g., hand, wrist) and the modulation of these specific pathways. CONCLUSIONS: Supplementing standard rehabilitation with a 4-week Tai Ji program was associated with significant improvement upper-limb limb motor function and activities of daily living in stroke patients. Mechanistically, these benefits were linked to a dual-process neural adaptation: strengthening of the descending corticomotor drive concurrent with facilitation of ascending sensory feedback and normalization of pathological muscle synergies. This bidirectional optimization of cortico-muscular connectivity may constitute a neurophysiological correlate of the observed functional improvements.