Effects of fast and slow squat exercises on the muscle activity of the paretic lower extremity in patients with chronic stroke

[Purpose] The purpose of this study was to investigate the effects of the speed of squat exercises on paretic lower extremity muscle activity in patients with hemiplegia following a stroke. [Subjects and Methods] Ten stroke patients performed fast and slow squat exercises for 2 seconds and 8 seconds, respectively. The muscle activities of the paretic and non-paretic sides of the rectus femoris muscle, the biceps femoris muscle, and the tibialis anterior muscle were assessed and compared using surface electromyography. [Results] The paretic side of the rectus femoris muscle showed statistically significant differences in the fast squat exercise group, which demonstrated the highest muscle activity during the rapid return to the upright position. [Conclusion] The rectus femoris muscle showed the highest muscle activity during the return to the upright position during the fast squat exercise, which indicates that the rectus femoris muscle is highly active during the fast squat exercise.Key words: Fast and slow squat exercise, Muscle activity, Chronic strokes     

Effects of lifting the non-paretic foot on muscle activity during the semi-squat exercise in hemiplegic patients

[Purpose] This study compared the electromyographic activity of the quadriceps in hemiplegic patients during the downward, maintenance, and upward phases of squat exercises performed with the feet parallel and with the non-paretic foot lifted. [Subjects] A total of 17 hemiplegic patients (9 males and 8 females) volunteered for this study. [Methods] All subjects performed squat exercises with the knees flexed to 30° and with the feet parallel (shoulder-width apart) or with lifting of the non-paretic foot (normalized to 25% of the knee height). [Results] The activity of the rectus femoris, vastus medialis oblique, and vastus lateralis muscles was significantly higher during squat exercises performed with the non-paretic foot lifted than with the feet parallel to each other. The activity of all muscles during the maintenance phase of the exercises was greater than that during the downward and upward phases. [Conclusion] Lifting the non-paretic foot during squats may represent an effective exercise for motor function rehabilitation in hemiplegic patients.Key words: EMG, Foot lifting, Squat exercise     

Effects of increasing non-paretic step length on paretic leg movement during hemiparetic gait: a pilot study

[Purpose] Gait training that increases non-paretic step length in stroke patients increases the propulsive force of the paretic leg. However, it limits knee flexion during the swing phase of gait, and this may cause gait disturbances such as worsening of gait pattern and increased risk of falling. Therefore, this study aimed to investigate the effects of increasing non-paretic step length on the joint movement and muscle activity of a paretic lower limb during hemiparetic gait. [Participants and Methods] A total of 15 hemiparetic patients with chronic stroke were enrolled in this study. Spatiotemporal parameters, along with kinematic and electromyography data of their paretic lower limbs, were measured during a 10-m distance overground walking. Two walking conditions were assessed: normal (comfortable gait) and non-paretic-long (gait with increased non-paretic step length) conditions. [Results] Under the non-paretic-long condition, the trailing limb angle was larger than under the normal condition. However, no significant difference was observed in the knee flexion angle during the swing phase. [Conclusion] Increasing non-paretic step length during gait is unlikely to limit knee flexion during the swing phase and can safely improve the propulsive force of a paretic leg.     

The characteristics of multi-directional step distance and the association between stepping laterality and walking ability of patients with stroke

[Purpose] The purpose of this study was to determine the effect of stepping limb and step direction on step distance and the association of step distance and stepping laterality in step difference with walking ability and motor dysfunction. [Subjects and Methods] The subjects were thirty-nine patients with chronic hemiparesis as a result of stroke, who performed the MSL (Maximum Step Length) test along with tests of motor impairment, gait speed and Functional Ambulation Category. The MSL test is a clinical test of stepping distance in which participants step to the front, side, and back. The subjects were classified into three groups according to the stepping laterality in front step distance. [Results] Step distance did not differ across stepping limbs but did differ across step directions. Front step distance was significantly longer than side and back step distance. Participants with forward paretic step length shorter than forward non-paretic step length had significantly higher walking ability than participants with symmetric forward step length or forward paretic step length longer than forward non-paretic step length [Conclusion] Patients with stroke have characteristic step distances in each direction. Adequate weight shift toward the paretic limb when stepping with the non-paretic limb is associated with walking ability.Key words: Maximum step length, Stepping laterality, Stroke     

Effects of a knee–ankle–foot orthosis on gait biomechanical characteristics of paretic and non-paretic limbs in hemiplegic patients with genu recurvatum

Background

A knee–ankle–foot orthosis may be prescribed for the prevention of genu recurvatum during the stance phase of gait. It allows also to limit abnormal plantarflexion during swing phase. The aim is to improve gait in hemiplegic patients and to prevent articular degeneration of the knee. However, the effects of knee–ankle–foot orthosis on both the paretic and non-paretic limbs during gait have not been evaluated. The aim of this study was to quantify biomechanical adaptations induced by wearing a knee–ankle–foot orthosis, on the paretic and non-paretic limbs of hemiplegic patients during gait.

Methods

Eleven hemiplegic patients with genu recurvatum performed two gait analyses (without and with the knee–ankle–foot orthosis). Spatio-temporal, kinematic and kinetic gait parameters of both lower limbs were quantified using an instrumented gait analysis system during the stance and swing phases of the gait cycle.

Findings

The knee–ankle–foot orthosis improved spatio-temporal gait parameters. During stance phase on the paretic side, knee hyperextension was reduced and ankle plantarflexion and hip flexion were increased. During swing phase, ankle dorsiflexion increased in the paretic limb and knee extension increased in the non-paretic limb. The paretic limb knee flexion moment also decreased.

Interpretation

Wearing a knee–ankle–foot orthosis improved gait parameters in hemiplegic patients with genu recurvatum. It increased gait velocity, by improving cadence, stride length and non-paretic step length. These spatiotemporal adaptations seem mainly due to the decrease in knee hyperextension during stance phase and to the increase in paretic limb ankle dorsiflexion during both phases of the gait cycle.     

A study of structural foot deformity in stroke patients

[Purpose] The aim of this study was to evaluate the structural deformity of the foot joint on the affected side in hemiplegic patients to examine factors that affect this kind of structural deformity. [Subjects and Methods] Thirty-one hemiplegic patients and 32 normal adults participated. The foot posture index (FPI) was used to examine the shape of the foot, the modified Ashworth scale test was used to examine the degree of ankle joint rigidity, the navicular drop test was used to investigate the degree of navicular change, and the resting calcaneal stance position test was used to identify location change of the heel bone. [Results] The FPIs of the paretic side of the hemiplegic patients, the non-paretic side of the hemiplegic patients, and normal participants were −0.25 ± 2.1, 1.74 ± 2.3, and 2.12 ± 3.4 respectively. [Conclusion] Our findings indicated that in stroke-related hemiplegic patients, the more severe the spasticity, the more supinated the foot. Further, the smaller the degree of change in the navicular height of hemiplegic patients is, the more supinated the paretic side foot is. Additionally, a greater change in the location of the calcaneus was associated with greater supination of the overall foot.Key words: Foot posture index, Hemiplegic foot, Foot deformity     

脑卒中患者不同强度随意运动时的sEMG反应特点

目的：观察不同强度静态及动态运动负荷对脑卒中患者四肢肌肉sEMG信号变化的影响,研究脑卒中患者四肢肌肉活动的表面肌电信号特征与其神经运动控制的关系。方法：24例脑卒中患者参加本项研究,采用患、健侧自身对照实验方法设计,采用上肢屈肘和下肢伸膝静态运动,以及肘关节和膝关节动态屈伸运动负荷试验,采集主动肌和拮抗肌的表面肌电信号,分析信号振幅和拮抗比值等sEMG信号活动特征。结果：最大用力收缩时,上、下肢患侧主动肌AEMG小于健侧,而拮抗比大于健侧;小强度静态运动负荷过程中,患侧上肢主动肌的AEMG略高于患侧,拮抗比明显大于健侧。患侧下肢股外侧肌（VL）、股直肌（RF）和股内侧肌（VM）的平均AEMG、?T标准化值大于健侧,拮抗比小于健侧;小强度动态运动负荷过程中,上肢患侧主动肌AEMG明显高于健侧。下肢患侧VL、RF和VM的AEMG均值具有增大趋势,但无明显差异。而患侧拮抗比明显小于健侧。结论：脑卒中患者由于高位神经元和运动控制功能受损,导致其患侧在最大随意收缩时运动单位募集能力下降,而在轻负荷运动时运动单位募集过度。     

Increased arterial stiffening and thickening in the paretic lower limb in patients with hemiparesis

Atherosclerosis has two key components, thickening and stiffening of arterial wall. These parameters are quantified ultrasonographically by IMT (intima-media thickness) and PWV (pulse wave velocity). In the present study, we determined the FA IMT (IMT of the bilateral femoral artery) and PWV of femoral-ankle (PWV fa) and brachial-ankle (PWV ba) segments in order to examine whether the degree of atherosclerosis is different between paretic and non-paretic lower limbs in 24 patients with hemiparesis. The values of PWV fa, PWV ba and FA IMT were all significantly greater on the paretic than the non-paretic side. Furthermore, significant decreases in masses of muscle, bone and fat, determined by dual-energy X-ray absorptiometry, were observed in paretic lower limbs compared with the non-paretic side. PWV fa correlated significantly and negatively with muscle mass ( r =-0.488, P =0.0004) and tended to correlate negatively with BMC (bone mineral content; r =-0.264, P =0.069) when statistical analyses were performed with the paretic and non-paretic sides together. Multiple regression analysis elucidated that the muscle mass was associated significantly with PWV fa and PWV ba, independent of age, duration after cerebrovascular accident, gender, bone and fat mass and FA IMT. The muscle mass was still associated with increased PWV fa and PWV ba when multivariate analysis was conducted independently in the paretic and non-paretic sides. In summary, our results indicated that arterial thickening and stiffening were greater on the paretic than the non-paretic side and suggested that a decrease of muscle mass might be associated with increased arterial stiffening in the paretic lower limb.     

姿势对脑卒中偏瘫患者站-坐转移下肢负重及稳定性的影响

目的:探讨不同的四肢体位对脑卒中偏瘫患者站-坐转移下肢负重及稳定性的影响。方法:选取30例脑卒中偏瘫患者为实验组,30例正常人为对照组,两组受试者均在4种肢位下完成站-坐转移,对受试者完成站-坐转移的时间、双下肢负重、人体重心点在冠状面上的最大摆动幅度(COGX)进行比较。结果:不同上肢体位下脑卒中偏瘫患者站-坐转移的所需时间、下肢负重及COGX的差异不显著(0.05P0.1)。不同足位下脑卒中偏瘫患者站-坐转移的时间、下肢负重及COGX有差异,差异具有显著性意义(P0.05);患足置后,脑卒中偏瘫患者完成站-坐转移时双下肢负重的不对称性要明显小于健足置后(P0.05);而当健足置后时,脑卒中偏瘫患者完成站-坐转移的稳定性要明显优于患足置后(P0.05)。正常人在不同四肢体位下其站-坐转移的时间、下肢负重及COGX均无显著性意义(P0.05)。结论:不同上肢体位对脑卒中偏瘫患者站-坐转移的稳定性及下肢负重无明显影响;不同足位能显著影响脑卒中偏瘫患者站-坐转移时稳定性及下肢负重,患足置后可视为一种潜在提高患侧下肢功能的训练方法。     

脑卒中患者坐位及站立位胫骨前肌和腓肠肌表面肌电图信号特征研究

目的分析脑卒中患者坐位及站立位胫骨前肌和腓肠肌表面肌电图(sEMG)信号特征。方法选取15例脑卒中患者和15例正常人作为实验组和对照组,令受试者连续做5次由坐到站,采用表面电极引导和记录两侧胫骨前肌和腓肠肌肌电信号并进行线性时、频分析。结果脑卒中患者坐位患侧与健侧、健侧与正常人对应健侧胫骨前肌的平均功率频率(MPF)和中位频率(MF)差异有显著性意义(P<0.05);脑卒中患者健侧与正常人对应健侧腓肠肌均方根差异有显著性意义(P<0.05);脑卒中患者站立位患侧与健侧、健侧与正常人对应健侧胫骨前肌均方根和积分肌电(iEMG)差异有非常显著性意义(P<0.01);脑卒中患者健侧与患侧、患侧与正常人对应患侧腓肠肌均方根和iEMG差异有显著性意义(P<0.05或P<0.01)。结论sEMG是一种简单、实用、可行的康复评定方法。     

Limited fascicle shortening and fascicle rotation may be associated with impaired voluntary force-generating capacity in pennate muscles of chronic stroke survivors

BackgroundMuscle weakness is one of the most common motor impairments after stroke. A variety of progressive muscular changes are reported in chronic stroke survivors, and it is now feasible to consider these changes as an added source of weakness. However, the net contributions of such muscular changes towards muscle weakness have not been fully quantified.MethodsAccordingly, this study aims: (1) to compare muscle architecture of the human medial gastrocnemius between paretic and non-paretic sides in seven chronic hemispheric stroke survivors under passive conditions; (2) to characterize fascicle behavior (i.e., fascicle shortening and fascicle rotation) of the muscle during voluntary isometric contractions; and (3) to assess potential associations between muscle architectural parameters and muscle weakness. Muscle architecture of the medial gastrocnemius (including fascicle length, fascicle pennation angle, and muscle thickness) was characterized using B-mode ultrasonography, and fascicle behavior was then quantified as a function of isometric plantarflexion torque normalized to body mass.FindingsOur experimental results showed that under passive conditions, there was a significant difference in fascicle length and muscle thickness between paretic and non-paretic muscles, but no difference in resting fascicle pennation angle. However, during isometric contraction, both fascicle shortening and fascicle rotation on the paretic side were significantly decreased, compared to the non-paretic side. Moreover, the relative (i.e., paretic/non-paretic) fascicle rotation-shortening ratio (i.e., fascicle rotation per fascicle shortening) was strongly correlated with the relative maximum voluntary isometric plantarflexion torque.InterpretationThis association implies that such fascicle changes could impair the force-generating capacity of the muscle in chronic stroke survivors.     

Differences in gastrocnemius muscle architecture between the paretic and non-paretic legs in children with hemiplegic cerebral palsy

BACKGROUND: The aim of this study was to investigate the architectural alterations of skeletal muscle following hemiplegic cerebral palsy. If associated with functional and clinical measures of disability, information on muscle architecture could then be used as an objective tool in the assessment of motor disability in these patients. METHODS: Ultrasonography was used to assess in vivo the gastrocnemius muscle architecture in the paretic and non-paretic legs of eight children with cerebral palsy. FINDINGS: Fascicle length and muscle thickness at the resting ankle position were reduced in the paretic compared to the non-paretic legs by up to 18% and 20%, respectively (P<0.05), indicating a loss of both in-series and in-parallel sarcomeres in the affected muscles. However, pennation angle was similar (P>0.05) in the two legs. INTERPRETATION: The present results indicate that paresis in hemiplegic cerebral palsy may affect the geometry of skeletal muscle. Further studies are required to examine the relation between muscle architecture, severity of motor disability, and treatment.     

Physique,range of motion,and gross muscle strength in hemiplegic para swimmers: a cross-sectional case series

[Purpose] The physical functions related to swimming should be evaluated to enhance competitive performance and prevent sports injuries. This study aimed to determine the physique, range of motion, and gross muscle strength of the limbs among hemiplegic para swimmers. [Participants and Methods] Three male para swimmers with hemiplegia and five male para swimmers with impaired vision were included in the study. The limb circumference, range of motion, quadriceps flexibility, and gross muscle strength were evaluated. The hemiplegic swimmers and swimmers with impaired vision were compared using an unpaired t-test. [Results] The maximum values of the upper and forearm circumferences; the range of motion for shoulder flexion, external rotation, ankle dorsiflexion on the paretic side; and the single-leg sit-to-stand test of the dominant limb were significantly lower in hemiplegic swimmers than in swimmers with impaired vision. [Conclusion] Hemiplegic swimmers had decreased upper limb circumferences on the paretic limb; the range of motion for shoulder flexion, external rotation, and ankle dorsiflexion on the paretic limb; and muscle strength on the dominant lower limb.     

Effect of the Modulation of Optic Flow Speed on Gait Parameters in Children with Hemiplegic Cerebral Palsy

[Purpose] We investigated the effects of modulation of the optic flow speed on gait parameters in children with hemiplegic cerebral palsy. [Methods] We examined 10 children with hemiplegic cerebral palsy. The children underwent gait analysis under 3 different conditions of optic flow speed: slow, normal, and fast optic flow speed. The children walked across the walkway of a GAITRite system, while watching a virtual reality screen, and walking velocity, cadence, stride length, step length, single support time, and double support time were recorded. [Results] Compared with the other applied flow speed conditions, the fast optic flow speed (2 times the normal speed) significantly increased walking velocity, cadence, normalized step length, base of support, and single support cycle of both the paretic and non-paretic lower limbs. Moreover, compared with the other applied flow speed conditions, the slow optic flow speed (0.25 times the normal speed) yielded a significantly decreased walking velocity, cadence, normalized step length, base of support, and single support cycle for both the paretic and non-paretic lower limbs. [Conclusion] The gait parameters of children with hemiplegic cerebral palsy are altered by modulation of the optic flow speed. Thus, we believe that gait training involving modulation of the optic flow speed is feasible and suitable for resolving abnormal gait patterns in children with hemiplegic cerebral palsy.Key words: Optic flow, Gait parameter, Hemiplegic cerebral palsy     

脑卒中患者四肢肌肉的表面肌电信号特征研究

目的：观察不同强度静态运动负荷对脑卒中患者四肢肌肉sEMG信号变化的影响，探讨脑卒中患者四肢肌肉活动的表面肌电信号特征。方法：15例脑卒中患者和15例正常人对照组参加本实验研究，利用静态运动负荷诱发上肢肘关节屈肌和下肢膝关节伸肌收缩，采用表面电极引导和记录肌电信号并进行线性时、频分析。结果：脑卒中患者患侧下肢股四头肌和上肢三角肌前部的AEMG和MPF均值明显小于健侧，运动负荷对各组观察肌肉MPF时间序列曲线斜率变化均无明显实验效应。结论：静态运动负荷条件下脑卒中患者患侧肌肉sEMG信号活动的振幅降低，频率下降。     

Knee joint movement and muscle activity changes in stroke hemiplegic patients on continuous use of knee-ankle-foot orthosis with adjustable knee joint

[Purpose] We aimed to evaluate knee joint movement and muscle activity ratio changes in stroke hemiplegic patients in recovery phase after using a knee-ankle-foot orthosis with an adjustable knee joint for 1 month; we also aimed to discuss the practical implications of our findings. [Participants and Methods] The participants were 8 hemiplegic patients in the recovery phase of stroke who were prescribed knee-ankle-foot orthosis with adjustable knee joint. We measured knee joint angles and electromyographic activity of the vastus medialis and biceps femoris during walking in two conditions: the knee-ankle-foot orthosis knee joint fixed in the extended position and the knee joint moved from 0° to 30° in the flexion direction. Measurements were taken 2 weeks after completion to account for habituation of the orthosis and repeated 1 month later. [Results] When the knee joint was moving from 0° to 30° in the flexion direction, the knee joint angle at initial contact and the minimum flexion angle of the gait cycle decreased significantly between the first and second measurements. When knee joint flexion was 30°, the muscle activity ratio of the vastus medialis increased significantly in the loading response and mid-stance compared to when it was fixed. [Conclusion] Setting the knee joint of a knee-ankle-foot orthosis in accordance with the knee joint movement may increase the muscle activity ratio of the vastus medialis from loading response to mid-stance.Key words: Stroke, Electromyography, Knee-ankle-foot orthosis     

上肢位及椅子高度对脑卒中偏瘫患者坐-站转移时下肢负重及稳定性的影响

目的：探讨上肢位及椅子高度对脑卒中偏瘫患者坐-站转移下肢负重及稳定性的影响。方法：脑卒中偏瘫患者30例,分别在双手叉握（GA）及双手交叉胸前（CA）两种上肢位及两种不同高度的椅子（高椅及标准椅）上完成坐-站转移测试,采用AL-080型步态与平衡功能训练评估系统对受试者完成坐-站转移的时间、双下肢负重、双下肢负重不对称性（IOA）及人体重心点（COG）在冠状面上的摆动幅度（COGX）进行测量,探讨其不同差异。结果：姿势GA时,除坐-站转移所需的时间外,健足平均负重、患足平均负重、IOA及COGX与姿势CA相比较,差异均有统计学意义（P〈0.05）。在高椅子上完成坐-站转移时,与标准椅子相比较,健足平均负重、患足平均负重及IOA无明显差异,而坐-站转移所需时间以及COGX均差异有统计学意义（P〈0.05）。左侧脑卒中偏瘫与右侧偏瘫相比较,坐-站转移所需时间、患侧下肢负重、健侧下肢负重、IOA及COGX均无差异（P〈0.05）。结论：不同上肢位影响脑卒中偏瘫患者坐-站转移的下肢负重及稳定性;椅子高度影响脑卒中偏瘫患者坐-站转移的稳定性。     

Changes in upper limb joint torque patterns and EMG signals with fatigue following a stroke

Purpose : Little is known concerning changes in neuromuscular fatigue following a stroke. The purpose of this study was to evaluate the effect of a stroke on fatigue-related changes in upper limb torque patterns and electromyographic signals.

Method : The paretic and non-paretic upper limb of 10 adults (51 - 79 years) who had a stroke (time since stroke: 3 - 75 months) were compared. Subjects had to perform a fatigue task consisting of a sustained maximal isometric contraction in elbow flexion until torque decreased to below 50% of initial. The main variables of interest assessed before, during and after fatigue were: (1) the torque in elbow flexion, as well as associated forces/torques at the shoulder and forearm; (2) the level of voluntary activation; (3) the amplitude (RMS); and (4) frequency content (median frequency) of electromyographic signals.

Results : Compared to the non-paretic side, the paretic side showed a lower level of voluntary activation and higher relative torque levels at the forearm and shoulder which could both be exaggerated with fatigue, and a lesser fatigue-related decrease in median frequency.

Conclusions : Thus, greater fatigue-related changes in features of the central command (ability to maximally activate a muscle and ability to isolate effort to a muscle group) were observed for the paretic compared with the non-paretic side. This could be a confounding factor when assessing changes in peripheral measures of fatigue following a stroke using voluntary contractions.     

The effects of symmetric center of pressure displacement training with feedback on the gait of stroke patients

[Purpose] This study investigated the effects of COP displacement training using visual feedback had on the gait of patients with hemiplegia due to stroke. [Subjects and Methods] This study was conducted with 20 patients with hemiplegia due to stroke. The training consisted of five training sets repeated 10 times and the activity was conducted for 15 minutes each session, three times per week for six weeks immediately after completion of central nervous system developmental treatment. [Results] A comparison of the results of before and after the experiment found that the COP displacement training group showed significant improvements in step length, stride length, gait velocity, and the functional reach test, while the control group showed significant improvement only in the functional reach test. In the intergroup comparison, the COP displacement training group showed significant improvements in paretic side step length, paretic side stride length, gait velocity, and the functional reach test compared to the control group. [Conclusion] In conclusion, according to the results of this study, visual feedback training for COP displacement is more effective at enhancing the gait and balance of hemiplegic patients due to stroke than only performing feedback training for even weight distribution.Key words: Stroke, Center of pressure, Feedback     

Changes in upper limb joint torque patterns and EMG signals with fatigue following a stroke

Purpose : Little is known concerning changes in neuromuscular fatigue following a stroke. The purpose of this study was to evaluate the effect of a stroke on fatigue-related changes in upper limb torque patterns and electromyographic signals. Method : The paretic and non-paretic upper limb of 10 adults (51 - 79 years) who had a stroke (time since stroke: 3 - 75 months) were compared. Subjects had to perform a fatigue task consisting of a sustained maximal isometric contraction in elbow flexion until torque decreased to below 50% of initial. The main variables of interest assessed before, during and after fatigue were: (1) the torque in elbow flexion, as well as associated forces/torques at the shoulder and forearm; (2) the level of voluntary activation; (3) the amplitude (RMS); and (4) frequency content (median frequency) of electromyographic signals. Results : Compared to the non-paretic side, the paretic side showed a lower level of voluntary activation and higher relative torque levels at the forearm and shoulder which could both be exaggerated with fatigue, and a lesser fatigue-related decrease in median frequency. Conclusions : Thus, greater fatigue-related changes in features of the central command (ability to maximally activate a muscle and ability to isolate effort to a muscle group) were observed for the paretic compared with the non-paretic side. This could be a confounding factor when assessing changes in peripheral measures of fatigue following a stroke using voluntary contractions.