The surface-electromyographic characteristics of the anterior and posterior thigh muscles in patients recovering from cerebral infarction

Objective To assess the contraction and coordination changes in the anterior and posterior thigh muscles of patients recovering from cerebral infarction,and to provide objective references for targeted rehabilitation programs. Methods Eighteen cerebral infarction patients with mild hemiparesis (the patient group) and eighteen age- and sex-matched healthy volunteers (the healthy group) were investigated. The surface-electromyographic (sEMG) signals of their vastus medialis,rectus femoris,vastus lateralis,biceps femoris,semitendinosus and semimembranosus were recorded during knee joint flexion and extension in the prone position.The sEMG signals from both legs were recorded for the patient group,but only from the left leg in the healthy group.The standardized root mean square (stRMS) signals and the co-contraction ratios (CRs) were compared and analysed, Results The stRMSs of the rectus femoris,vastus lateralis and vastus medialis on the patients' affected side during knee extension were significantly higher than those in the healthy group at baseline and follow-up.The stRMSs of the biceps femoris and semitendinosus-semimembranous on the patients' unaffected side were significantly higher than those of the affected side and the healthy group during knee flexion at baseline.The CRs during knee flexion on the patientsˊ affected side at baseline and follow-up were significantly higher than those of the unaffected side at baseline. Conclusions After cerebral infarction,the functioning of both the anterior and posterior thigh muscles on the affected side are impaired.The rectus femoris are the most severely impaired knee extensors,and the biceps femoris,semitendinosus and semimembranous are impaired equally in knee flexion.The thigh flexors and extensors lose their normal antagonist-agonist contraction modes.The functions of both the anterior and posterior thigh muscles should be emphasized during rehabilitation to improve abnormal contraction. Key words: Infarction ;  Thigh muscles ;  Surface-electromyography ;  Rehabilitation