Padrão de coordenação neuromuscular dos membros inferiores de hemiparéticos crônicos durante o movimento de sentado para de pé

Abstract

The sit to stand (STS) movement is a functional activity frequently performed in daily life that requires coordination, balance, mobility and strength. After a cerebrovascular accident, subjects often demonstrate hemiparesis, spasticity and incoordination while performing functional tasks, such as the STS movement. This incoordination may result from changes in activation, in sequence, in temporal regulation and in graduation of muscular activity, which can define, in a certain degree, the quality and impairments during STS. However, there are few studies about the muscle activation pattern of lower limbs in stroke survivors throughout this task. The purpose of the current study was to investigate the neuromuscular coordination pattern of paretic and non-paretic lower limbs in chronic hemiparetic subjects during the STS movement. Participants should be between 60 and 75 years old and they should be able to stand from a chair without assistance. Lower limbs muscle torque, gait speed, muscle tone and number of falls in the last six months were measured for characterization of the sample. The following variables were analyzed during STS: movement time, time to seat-off, onset latency, duration, differential latency, time to maximum peak activity and electromyographic quantification (EMGQ) of tibialis anterior (TA), soleus (SOL), quadriceps (QUA) and hamstrings (HAM) muscles. Descriptive statistics, Students T-test and One-way ANOVA were carried out for data analyzes, considering a< 0.05. Seventeen subjects were included with mean age 68.65 ± 4.66 years. Mean movement time and time to seat-off were 1.99 ± 0.35s and 0.54 ± 0.18s, respectively. All paretic and non-paretic muscles showed prolonged activity and negative differential latency. Earlier activation of HAM and higher EMGQ of TA, SOL and QUA happened on the non-paretic leg. Two abnormal recruitment patterns were found on the paretic lower limb and concurrent onset activity happened for all muscles on the non-paretic side. For all muscles of both limbs, time to seat-off was significantly different from time to peak activity (p<0.01). Therefore, during the STS movement, neuromuscular coordination abnormalities were observed on both lower limbs of hemiparetic subjects. Changes in recruitment time and amplitude were found on the paretic leg, while significant compensations occurred on the non-paretic lower limb.