Standing Balance And Locomotion Gait During Post-Stroke Rehabilitation

The morbidity of stroke is increasing year by year.Nowadays,the number of stroke patients has been 13 million in China.The stroke causes the central nerve system injury.The motor function disorders and high rate of disability have been found in stroke survivors.The recovery of balance ability and gait function is the primary goal of rehabilitation training for post-stroke patients.This study investigated the balance function,muscle control during quiet standing and the associations between gait and lower-limb muscle activities in individuals post-stroke.The significances of this study were finding the motor control pathological mechanism during standing and walking and guiding clinical balance and gait rehabilitation for post-stroke patients.This paper completed following main works:(1)Research on standing balance ability in post-stroke rehabilitation.Balance ability is the foundation of motor function.It has been observed in post-stroke patients that unilateral limb numbness generated balance deficiency,postural instability and risk of falls.The center of pressure(COP)and center of mass acceleration(COMA)signals were used to evaluate the standing balance ability.This study designed quiet standing experiment of post-stroke patients,applied modified detrended fluctuation analysis(DFA)algorithm to calculate the COP area,COP speed,COP displacement,standard deviation(SD)of COMA and structural variability of COMA(a)in anterior-posterior(AP)and medial-lateral(ML)directions.Results showed that differences were found between stroke and control in ML-COP displacement,COP area,SD and a of AP-COMA,and a of ML-COMA(p<0.05).These findings revealed that the COP displacement transfered to the non-paretic side;postural stability decreased;the synchronicity between COP and COM declined;and the flexibility of balance control losed in post-stroke individuals.(2)Research on lower-limb SEMG during standing in post-stroke rehabilitation.Lower-limb neuromuscular control plays a role to balance.The declined balance ability in post-stroke patients was related to abnormal muscle activities in lower limbs.The study synchronously recorded SEMG signals of rectus femoris(RF),biceps femoris(BF),tibialis anterior(TA)and gastrocnemius(GA)in above standing balance experiment.The root mean square(RMS)and mean frequency(MF)algorithms were used to calculate 8 SEMG parameters:RFRMS、BFRMS、TARMS、GARMS、RFMF、BFMF、TAMF、GAMF.Results found significant differences between the paretic side group and non-paretic side group in TARMS、GARMS、RFMF、TAMF(p<0.05);between the non-paretic side group and control group in TARMS、GARMS、RFMF、BFMF、TAMF(p<0.05).These findings revealed that the muscular contraction strength of TA and GA,and firing frequency of RF,BF and TA increased in the non-paretic side;the TA played a key role to balance control;and this standing pattern was not facilitated to maintaining posture stability of post-stroke individuals.(3)Associations between gait and lower-limb muscle activities in post-stroke rehabilitation.Reduced knee flexion is a leading feature of post-stroke gait,but the causes have not been well understood.The gait experiment synchronously recorded both lower-limb kinematics and SEMG signals from RF、BF、GA muscles in individuals post-stroke and healthy subjects.The range of knee flexion(ROKF),RFRMS,BFRMS,GARMS,RFMF,BFMF and GAMF were calculated.There were significantly differences in ROKF,GARMS,RFMF,GAMF between the paretic side group and non-paretic side group(p<0.05).Results of bivariate correlation analysis showed that ROKF was positively correlated with RFRMS,BFRMS,GARMS,GAMF in the paretic side group;was negatively correlated with BFRMS and BFMF in the control group;was positively correlated with RFMF in the non-paretic side group.Results of regression analysis showed that ROKF was affected by BFRMS,BFMF and GAMF in the paretic side group(r2 = 0.821).In the non-paretic side(r2 = 0.656)and control groups(r2 = 0.452),all the SEMG parameters(RFRMS,BFRMS,GARMS,RFMF,BFMF and GAMF)affected the ROKF.These findings revealed that the flexion ability of knees in the paretic and non-paretic sides decreased;the amplitude and frequency characteristics of RF and GA activities were impaired;and the simplified muscular coordination may be contributed to the declined flexion ability of knee after stroke.