Correlation between the changes of surface electromyographic signals of elbow flexor and extensor and motor function in stroke patients

Abstract

To explore the correlation between the changes of surface electromyography (sEMG) signals of biceps and triceps and torques for elbow flexion and extension during maximum isometric voluntary contraction (MIVC) and motor function in convalescent stroke patients so as to provide rationale for rehabilitation. Fifteen stroke patients and 15 age and gender-matched normal controls were recruited. The sEMG signals of biceps and triceps were recorded during MIVC of elbow flexion and extension. Co-contraction ratio (CR) and torques of both groups were compared and analyzed. The motor function of upper extremity was assessed by Fugl-Meyer assessment upper extremity (FMA-UE). There were significant differences in EMG ((132 ± 65) mV×s,(124 ± 50) mV×s) and torques ((13 ± 8) N×m, (10 ± 6) N×m) at affected side with those at unaffected side and controls during MIVC of elbow flexion and extension (P < 0.05).Significant differences existed in CR ((30 ± 13)%) at affected side with unaffected side ((18 ± 8)%) and controls ((16 ± 6)%) during MIVC of elbow extension (P < 0.05). The score of FMA-UE at affected side was significantly positively correlated with iEMG on biceps during MIVC of elbow flexion (r = 0.579, P = 0.024) and on triceps during MIVC of elbow extension (r = 0.618, P = 0.014). The score of FMA-UE at affected side was significantly positively correlated with torques during MIVC of elbow flexion and extension (rflexion = 0.518, P = 0.048; rextension = 0.679, P = 0.005). The score of FMA-UE at affected side was significantly negatively correlated with CR during MIVC of elbow flexion and extension (rflexion = -0.579, P = 0.024; rextension = -0.693, P = 0.004). The strength of flexor and extensor of bilateral elbow decreases in convalescent stroke patients. The spasticity of elbow flexor still exists. Besides increasing the strength of bilateral upper extremities, particularly affected side, rehabilitation should also focus upon reducing spasticity of flexor to enhance elbow joint stability and improve motor function.