Analysis Of The Characteristics Of Dynamics And EMG In The Lower Limbs In Individuals With Chronic Stroke When Perform STS Task

Purpose: Stroke is a serious hazard to human health and life safety of common refractory disease. The purpose of this study was comparing the differences of surface electromyography activities and joint torques between lower extremity, and investigating the relationship of lower extremity joint torques and sit-to-stand(STS)performance in individuals with chronic stroke, which would help us to comprehend the machine made and balance strategy during the sit-to-stand(STS) task.Methods: A total of 15 subjects were chosen from Hua Shan Hospital Rehabilitation Department and each sub-center outpatient. Subjects stand from a seat station for three times, with enough rest time between trials. They are required to hold both hands, put arms to the horizontal plane to prevent any support from the arms, stand on two force plates(one per foot). Dynamics and surface electromyography activities were calculated and analyzed. Main index include RMS of surface electromyography activities, Weight-Bearing Symmetry and maximum concentric joint torques of the paretic and nonparetic ankle, knee, and hip. which were normalized by body mass.Result:(1)There was no significant difference between erector spinaes of paretic and nonparetic. Medial head of gastrocnemius of the nonparetic was more activity than the paretic. And there was significant difference between paretic and nonparetic in the rectus femoris, medial vastus, vastus lateralis, tibialis anterior and caput laterale.(2)All subjects stand up from seat with weight-bearing asymmetrytowards the nonparetic leg. The average Weight-Bearing Symmetry was 0.71±0.21. And greater weight-bearing symmetry related to duration of STS condition.(3)There was no significant difference between both hips maximum extension torques in both phases. The nonparetic hip in the first phase had a significantly higher flexor muscle torques than the paretic side. There was significant difference between both knees maximum extension torques in both phases, and no significant difference between both ankles plantar flexion torques.(4) The nonparetic maximum hip flexor muscle torques related to the duration of each phases during STS. The paretic maximum knee flexor muscle torques related to the duration of first phase. The nonparetic maximum ankle plantar flexion torques related to the duration of each phases during STS.Conclusion:(1) The nonparetic had a preponderance Weight-Bearing, with significant compensation towards the paretic.(2)There was Weight-Bearing Asymmetry when perform STS task in individuals with stroke. And higher Weight-Bearing Symmetry lead to longer STS duration.(3) The nonparetic had higher muscle activities than the paretic.(4) The nonparetic hip extension and ankle plantar flexion had a significant compensation action in both phases, along with flexion of hip and dorsal flexure of ankle. The paretic knee extension had more influence in the first phase, The knee extension strength was the keywords to recover the ability of STS task.