Post-stroke asymmetry of muscle contractions for knee flexion and extension during walking

Patients with stroke usually have abnormal gait during walking. A hallmark of the post-stroke gait is the decreased knee flexion on the paretic leg compared to the non-paretic side. The objective of this study was to investigate the muscle contractions that are potentially responsible for the asymmetry of knee flexion in post-stroke patient. Ten stroke patients and 10 age- and sex-matched healthy controls were recruited. Kinematic signals were recorded using a motion analysis system by capturing the reflective markers attached on the both legs. Surface electromyography (sEMG) signals were collected using on the rectus femoris (RF) muscle, the biceps femoris (BF) muscle and the gastrocnemius (GAS) muscle. Asymmetry ratio of the knee angle range (KAR), as well as the root mean square error (RMSE) of the sEMG during knee joint flexion and extension within one gait cycle was calculated. We found that most patients were different from healthy subjects in the asymmetry ratio of KAR during flexion (p <; 0.05), and extension (p <; 0.01). The RMSE of the RF of non-paretic side in stroke patient was different from that of healthy control during extension (p <; 0.05). There were differences in RMSEs of the GAS of both sides between two groups during flexion in paretic side (p <; 0.05) and non-paretic side (p <; 0.05). Differences were found in RMSEs of GAS of both stroke (p <; 0.05) and control (p <; 0.05) between two sides during flexion. Comparing the gait symmetry and the situations of muscle contractions between people after stroke and healthy people could guide the clinical rehabilitation of stroke patients.