The influence of accuracy constraints on EMG and kinetic variables during gait initiation

[Purpose] This study investigated the effects of accuracy constraints (targets) placed on the stepping-limb heel-strike (HS) on the electromyogram (EMG) and ground reaction forces (GRFs) during gait initiation. [Subjects and Methods] Twenty healthy subjects (29.2 ± 2.9 years) were asked to begin walking or stepping over a 10-cm-high obstacle at a fast speed. A 3-cm-diameter target was placed on the ground to dictate the position and accuracy of the stepping-limb HS. [Results] The results showed that the initiation velocity increase in the no-target conditions was due to modulation of the stance- and stepping-limb GRFs and a corresponding increase in the tibialis anterior (TA) activities of both limbs before stepping-limb toe-off. This was achieved by significantly increasing the stepping- and stance-limb TAEMG1 (determined between the onset of movement and time to peak anteroposterior (A-P) GRF of the stepping- and stance- limb) for the no-target conditions. It seems, therefore, that TAEMG1 and the slope to stepping-limb peak A-P GRF contributed to the intended velocity of initiation. [Conclusion] These data indicate that gait initiation and/or stepping over an obstacle may prove to be tasks by which motor control can be measured. The present study provides insight into the working mechanisms of the stepping and stance limbs and shows a clear need to further investigate whether the intact or affected limb should be used to initiate gait during rehabilitation and prosthetic training.Key words: Electromyogram, Gait initiation, Ground reaction forces     

Assessing the reliability of measurements from the Krusen limb load monitor to analyze temporal and loading characteristics of normal gait

This study assessed the reliability of measurements made by four physical therapists on healthy subject gait data recorded from the Krusen limb load monitor. The five components of step (stance time, time up, time to second peak, and force at the first and second peaks) were analyzed. Six components contributing to gait (ambulation time; velocity; cadence; average swing phase duration, left lower extremity; average swing phase duration, right lower extremity; and ratio of unilateral weight bearing, right lower extremity to left lower extremity) were also analyzed. Intraclass correlation coefficients for the five step components and the gait measures of ambulation time, velocity, and cadence showed high measurement reliability. The other measures of gait showed low intraclass correlation coefficients. The limb load monitor can, therefore, be used by clinicians to measure the five step components and three gait measures (ambulation time, velocity, and cadence) with high measurement reliability.     

The initiation of gait in lower limb amputees: some related data

The initiation of gait, from balanced standing position to the toe-off of the stance leg, was analyzed in 8 unilateral above-knee (AK) and 10 unilateral below-knee (BK) males amputees. Thirty-one parameters were measured, including ground-foot forces and the movements and timing of hip, knee, and ankle joints. The significant changes from the normal pattern of initiation of gait found in the AK and BK amputees, as well as significant changes between the two amputees groups themselves, are described. The amputees were divided into two subgroups: those who start walking with their prosthesis and those starting with their normal leg. The two groups were compared statistically for each amputation level and all were compared to a normal subjects group. Differences relating to the choice of the swing leg were found. The findings are reported as part of a future databank.     

Effect of lower limb on body propulsion.

The purpose of this study was to analyze and compare the effects of the leg during swing and stance phases of forward propulsion of the body for both men and women. Twelve able-bodied subjects, six men and six women, were studied with a Vicon(a) gait-analysis system. A two-dimensional, sagittal-plane biomechanical analysis featuring a link-segment model was used to determine the force at the hip in the horizontal direction. Integrating this force curve over time during the swing and stance gait phases produced linear impulses, representing swing and stance contributions to the propulsion of the body, and it allowed quantitative comparisons using student t and Fisher tests. The deceleration of the swing leg was found to be the major contributor to the forward propulsion of the body. The stance leg initially exerted the major restraining or negative impulse during early stance; then it generated a positive impulse during push-off in late stance. A typical pattern of gait impulses was defined for normal gait. Male and female gait impulses were not significantly different for all gait phases.     

Modeling and simulation of muscle forces of trans-tibial amputee to study effect of prosthetic alignment

BackgroundThe muscle forces tend to change when any musculoskeletal system is damaged. It is necessary to predict and explain the patterns of muscle forces in the stump of a left trans-tibial amputee during walking, and to study the effects of the prosthetic alignment.MethodsMusculoskeletal modeling and computer simulation were combined to calculate muscle forces in the trans-tibial lower limb during walking. The prosthesis was aligned to be in optimal position for the subject and then changed into +6° and −6° in the sagittal plane relatively. Kinematic data of the stump wearing a prosthesis and ground reaction forces were simultaneously recorded by a gait analysis system and a force platform, respectively. The data were input into a model of the lower trans-tibial extremity with three-dimensional geometry and the corresponding seven muscle forces were predicted by a static optimization.FindingsMuscles performed much more actively in stance than in swing phase. Most muscles appeared very active around both heel-strike and toe-off. Muscle forces predicted were similar to that in temporal distribution at all three alignment conditions but the major muscles such as gluteus maximus, hamstrings, vasti and rectus femoris generated remarkable greater forces in −6° and +6° alignments than the normal condition.InterpretationThe above results showed the muscle forces increasing at the mal-alignment. Because the incorrect alignment could break the relative position of the socket and foot, and that would generate the extra joint moments. As a result, muscle forces increased, and the long-duration fatigue occurs more easily. The finding suggests that the proper prosthetic alignment is very important for the stump muscles normal activities.     

Kinematic effects of different gait speeds during gait initiation movement

[Purpose] We investigated the influence of gait speed on the movement strategy during gait initiation. [Participants and Methods] This study included 21 young healthy individuals (11 males and 10 females; mean age, 21.7 ± 0.5 years; mean height, 166.1 ± 9.8 cm; and mean weight, 57.3 ± 11.2 kg). A three-dimensional motion analyzer and strain gauge force platform were used in this study. The measurement task consisted of gait initiation from the quiet stance; the two measurement conditions were normal gait and the highest speed. The analysis interval was from the start of the center of pressure migration to the heel contact at the first step of the swing limb. The center of gravity, center of pressure, joint movements, step length, and step time during the anticipatory postural control (from the start of center of pressure migration to swing leg-heel off) and swing (swing leg-heel off to swing leg-heel contact) phases were analyzed. [Results] Significant differences were observed in the center of gravity, center of pressure, hip flexion, abduction movement, stance-limb ankle dorsiflexion movement during the anticipatory postural control phase, and step time during the anticipatory postural control and swing phases. The stance-limb ankle plantar flexion movement and step length did not differ significantly in the swing phase. [Conclusion] When the gait speed increases, fluctuations in the joint movements increase as the center of pressure displacement increases, thus requiring complex control.     

Lower limb muscle power relationships in bilateral able-bodied gait.

OBJECTIVE: The purpose of this study was to test the hypothesis that limb propulsion is mainly associated with the interaction of a number of muscle power bursts developed throughout the stance phase and that the control actions are mainly achieved by the contralateral limb through different power-burst interactions. We also hypothesized that the power activities of the propulsion limb would be related to those of the control limb. DESIGN: Sixty gait trials of 20 subjects with dominant right hands and right legs were chosen for analysis. Each trial represents a performance of an able-bodied gait. Data were assessed using an eight-camera, high-speed, video-based system synchronized to two force plates. The muscle powers and their related mechanical energies were calculated at each joint and in each plane of the lower limbs by use of an inverse dynamic technique. The Pearson correlation method was used to determine the relationships within each limb by use of the data identified by principal component analysis, whereas a canonical correlation analysis was performed to illustrate the interaction between the limbs. RESULTS: Gait propulsion was an activity initiated by the hip shortly after heel-strike and maintained throughout the stance phase. Control was the main task of the left limb as evidenced by the power absorption bursts at the hip and knee. The left limb power generations were generally secondary to control activities and were possibly involved in adjustments to correct the other limb's propulsion. Interlimb interaction further emphasized the functional relationship between forward progression and control tasks developed by each limb and highlighted the importance of the frontal and transverse plane actions during gait. CONCLUSION: These results do not support the hypothesis that the ankle was a major contributor to forward progression.     

核心稳定性训练对脑卒中偏瘫患者步态时空参数和对称性参数的影响

摘要 目的：应用步态分析,观察核心稳定性训练对脑卒中偏瘫患者步态时空参数和对称性参数的影响。 方法：选取脑卒中偏瘫患者60例,按随机数字表法将其分为观察组及对照组,每组30例。两组均进行常规治疗,观察组在此基础上给予核心稳定性训练。分别于治疗前和治疗6周后使用三维步态分析仪器检测并获得两组患者的步态参数。 结果：治疗6周后,两组患者步频、步幅、步速、患侧摆动相和健侧摆动相均较治疗前明显提高（P<0.01）,步宽、步态周期、双支撑相、患侧支撑相、健侧支撑相、步长偏差、健侧患侧支撑相比值和患侧健侧摆动相比值均较治疗前显著减小（P<0.01）。组间比较显示,观察组患者的步频、步幅、步速、步宽、步态周期、双支撑相、健侧支撑相、健侧摆动相、步长偏差、健侧患侧支撑相比值和患侧健侧摆动相比值改善均明显优于对照组（P<0.05或0.01）。 结论：核心稳定性训练能有效改善脑卒中偏瘫患者步态时空参数和对称性参数,提高脑卒中偏瘫患者的步行功能和步态的对称性。     

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.     

Legendre polynomial coefficients in the analysis of the horizontal and lateral component of the force plate measurements for an osteoarthritic gait

The assessment of force plate measurement obtained from subjects with a pathological gait, normally carried out by visual examination of the force-time data, can be augmented by consideration of Legendre polynomial coefficients. The first seven coefficients are evaluated and presented for the horizontal (forwards) and lateral (sideways) components of the force-time curves. It is shown that for an accurate assessment of specific osteoarthritic abnormalities it is necessary to consider the horizontal and lateral component data in addition to that previously presented for the vertical component.

Relevance

The Legendre analysis identifies the major gait factors from the shape of the curves and gives a reliable method of reducing the dynamic data to a simple set of numerical values by formalizing the classic approach of visual examination of the force-time curves. The method is particularly suitable for assessing the clinical gait condition in respect of heel-strike, toe-off, and stability.     

Electric discharge patterns of ankle muscles during the normal gait cycle

EMG patterns in ankle muscles were examined during normal gait cycles in 147 healthy asymptomatic adults. In all subjects, the tibialis anterior (Ta) showed marked activities around the toe-off and before the heel-strike, and the gastrocnemius lateral head (Gl) showed marked activity during the midstance phase but no activity in the early part of the swing phase. The Ta activity contributed to ground clearance, prevention of foot-drop, and shock absorption at the heel-strike. The Gl activity contributed to push-off from the ground and prevention of foot-drop. The Ta activity consisted of double bursts with (15% of subjects) or without (44%) electric silence in the midswing phase, continuous discharge (33%), and triple discharge patterns (8%). The Gl activity consisted of a single-peak (95%) pattern or double-peak (5%) patterns.     

The effects of light touch cue on gait initiation in patients with Parkinson's disease

IntroductionOne of the common impairments in patients with Parkinson's disease (PD) is disturbance of gait initiation. A light touch cue improves postural stability in patients with PD. Little is known about the effects of a light touch cue on gait initiation. This study investigated the effects of a light touch on gait initiation in patients with PD.MethodsThis study was a cross-sectional study design. Sixteen patients with PD (Hoehn & Yahr stage 2–3) participated in the study and were evaluated two gait conditions (no touch (NT) and light touch (LT) conditions). Gait initiation was divided into 5 events including event A, B, C, D, and E. Outcome measures included maximum center of pressure (COP) displacement and velocity in anteroposterior (AP) and mediolateral (ML) directions, and the first step time.ResultsParticipants with LT had greater COP displacement compared with the NT condition in all events of gait initiation except COP-AP displacement in event D. Additionally, the COP velocity in LT condition was faster than the NT condition in COP-ML velocity in event A, COP-AP velocity in event B, COP-AP velocity and COP-ML velocity in event C. Moreover, participants with LT presented significantly shorter the first step time than the NT condition.ConclusionsThese findings demonstrated that a light touch cue improved gait initiation in patients with PD by increased weight shifting to initial stance limb, increased postural stability of stance limb, increased velocity of weight transfer toward stance limb, and a shortened first step time.     

偏瘫步态髋关节角度研究

目的分析偏瘫患者步态的髋关节角度特征。方法对20例偏瘫患者和年龄、身高、体重匹配的20例正常人进行步态分析,分析其髋关节特征。结果偏瘫患者患侧髋关节首次着地时刻、站立相最大伸展角度、足尖离地时关节角度、迈步相最大屈曲角度、矢状面膝关节角度范围与正常人的差异存在显著性意义。结论研究偏瘫步态髋关节特征可协助进行临床评价及制定针对性步态矫正方案。     

Asymétries chronométriques, cinétiques et cinématiques de l''initiation de la marche chez un sujet hémiplégique

OBJECTIVE: To investigate the temporal, kinetic and kinematic asymmetry of gait initiation in one subject with hemiplegia with an equinus varus foot. MATERIAL AND METHODS: A kinetic analysis with two AMTI force plates and a kinematic analysis with an ELITE optoelectronic system of gait initiation were performed in one subject with hemiplegia. RESULTS: The duration of the gait initiation phases was asymmetrical. The monopodal phase was shorter when the affected lower limb was supporting than when the healthy one was supporting. The propulsion resulted from the force exerted on the healthy lower limb. The distribution of body weight on the lower limbs was asymmetrical. Body weight support was more important on the healthy side than on the affected side. Maximal extension of the ankle on the hemiplegic side occurred during the swing phase. Ground clearance was increased by elevating the knee higher on the affected side than on the healthy side during the swing phase. Initial contact with the floor was performed with the foot flat on the affected side. CONCLUSION: This preliminary study has shown that gait initiation in one subject with hemiplegia was asymmetrical in kinetics and kinematics. The results concerning kinematics have not been reported previously for gait initiation in subjects with hemiplegia. The study of gait initiation should allow for better understanding postural and movement control strategies developed by patients with hemiplegia.     

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.     

Ankle muscle activity during gait in children with cerebral palsy and equinovarus deformity

Temporal electromyographic (EMG) characteristics of lower limb muscles during gait of spastic hemiplegic and diplegic children with cerebral palsy are described. All subjects were referred for presurgical evaluation of equinovarus deformity. The data indicated both similar and discriminating phasic EMG characteristics between groups of patients. All children displayed premature triceps surae activity beginning in swing phase of gait and continuing through stance. Tibialis posterior, normally active during stance, was also active during swing phase of gait. However, some patients displayed cocontraction of triceps surae and tibialis anterior during stance, together with hamstring muscle activity within normal limits. The remainder of the patients displayed a prolonged duration of hamstring activity. How this gait analysis contributed to presurgical decisions for equinovarus gait is discussed and compared with data from postsurgical gait analysis.     

放散式体外冲击波对脑卒中患者下肢痉挛及三维步态参数的效果研究

摘要 目的：观察放散式体外冲击波对脑卒中偏瘫患者下肢痉挛,步态时空、对称性参数以及运动学参数的影响。 方法：选取40例符合入选标准的脑卒中偏瘫患者,将其随机分为试验组及对照组,每组20例。试验组进行常规康复治疗和患侧下肢放散式体外冲击波治疗（每周2次）,连续3周,对照组进行常规治疗和安慰性冲击波治疗。分别于治疗前、第三周全部治疗结束后使用三维步态分析仪器检测并获得两组患者的步态参数。同时比较两组患者治疗前后腘绳肌、股四头肌、小腿三头肌改良Ashworth分级（MAS）评分,以及患侧下肢的Fugl-Meyer（FMA）评分。 结果：在第三周治疗结束后,两组患者步频、步幅、步速、患侧摆动相和健侧摆动相、踝关节最大背屈角度、踝关节最大跖屈角度均较治疗前明显提高（P<0.05）,步态周期、双支撑相、患侧支撑相、健侧支撑相、步长偏差、患侧健侧摆动相比值均较治疗前明显减小（P<0.05）。组间对比显示,治疗后试验组患者步幅、步频、步速、步态周期、步长偏差、踝关节最大背屈角度、踝关节最大跖屈角度均优于对照组（P<0.05）。治疗后试验组腘绳肌、股四头肌、小腿三头肌MAS评分及患侧下肢FMA评分均较治疗前改善(P<0.05),并优于对照组(P<0.01,P<0.05)。 结论：放散式体外冲击波能有效改善脑卒中偏瘫患者步态时空、运动学、对称性参数,提高脑卒中偏瘫患者的步行功能和步态的对称性。同时可以降低患侧下肢的痉挛,提高下肢运动功能。     

A comparison of treadmill walking and overground walking in independently ambulant stroke patients: a pilot study

Purpose. The purpose of the study was to compare the spatio-temporal and joint kinematic gait parameters of stroke patients walking on a treadmill and overground, to examine the assumption that patients walking on a treadmill will approximate the requirements of walking overground. Methods. Ten independently ambulant chronic stroke patients were included in the study. Vicon was used to collect spatio-temporal and joint kinematic data during overground walking at comfortable speed and at matched speed on the treadmill. Results. Walking on the treadmill demonstrated statistically significantly lower cadence, and longer step times of the non-hemiplegic and hemiplegic limbs. Absolute stance times of both limbs, absolute double support time, relative stance time and relative double support time were significantly longer during treadmill walking. Compared to overground walking, the inter-limb symmetries of step time, stance time, and stance/swing time ratio were significantly greater on the treadmill. During treadmill walking, joint kinematic data showed statistically significant changes with greater flexion of the nonhemiplegic knee and hip at initial contact, and less hip extension of the hemiplegic limb. Maximal ankle plantarflexion and knee extension of the hemiplegic limb occurred later in the gait cycle on the treadmill. Conclusion. These differences suggest it may be useful to use treadmill in conjunction with overground walking to focus on improving specific walking deficits in patients with stroke.     

Walking reeducation with partial relief of body weight in rehabilitation of patients with locomotor disabilities

This study was undertaken to investigate the contribution of a weight-relieving system on the gait of patients with severe locomotor disabilities. Temporal parameters of gait and subjective evaluations of the effect of the system were studied in 24 patients and 6 healthy subjects. Partial weight relief was accomplished through a pneumatic system mounted in the ceiling over a conductive walkway which was placed between parallel bars. Subjects were tested in three walking trials: free walking, walking while harnessed to the system but without weight relief, and walking with relief of 20 percent of their body weight. Temporal measurements indicated a positive effect of the system on duration of the stance and swing phases. The percentage of the stance period of the involved lower limb relative to the uninvolved one increased by 148 percent; at the same time, the swing period of the involved limb relative to the sound one decreased to 68 percent of that value in free ambulation. A substantial increase in gait symmetry and velocity were also noted. Subjective information from the patients and observers also pointed to a facilitative effect of the system on the patients' ambulation. Conversely, natural gait velocity of the healthy subjects was impeded by weight relief through the system.     

Insights into amputee running. A muscle work analysis.

Five young, active, unilateral below knee amputees wearing the SACH prosthetic foot, and six normal subjects participated in the study. Subjects ran at a controlled velocity of 2.8 m/s +/- 10% over a ground reaction force plate while being filmed with a video camera. Joint moments, power outputs and mechanical work characteristics were then calculated. During stance phase the amputee prosthetic limb exhibited a marked reduction in total work. There was a reduction in the mechanical work at the knee and the prosthetic foot/ankle with a compensatory increase in mechanical work by the hip musculature. The intact stance phase limb mechanical work characteristics were not significantly different from normal. The hip flexors were the only muscle group in the swing phase prosthetic limb with a significant increase in muscle work compared with normal subjects. The intact swing phase limb in contrast exhibited a marked increase in concentric muscle work by the hip flexors and eccentric muscle work by the knee flexors in early swing phase, and an increase in concentric hip extensor and eccentric knee flexor muscle work in late swing phase. The major compensatory patterns, therefore, that allow below knee amputees to run appear to be an increase in stance phase hip muscle work on the prosthetic limb and increased hip and knee muscle work on the intact limb during swing phase.