Gait In Healthy Subjects Research Articles

Effects of Cerebellar Transcranial Alternating Current Stimulation on Gait and Balance in Healthy Subjects

Transcranial Alternating Current Stimulation (tACS) is a non-invasive brain stimulation technique [1] able to modulate neural oscillatory activities, including those linked to the cortico-cerebello-thalamo- cortical network [2,3]. In this double-blind sham-controlled study, we aimed to investigate the effects of cerebellar tACS delivered at theta and gamma frequencies on gait and balance in healthy subjects, as assessed by kinematic techniques. In a group of young healthy subjects, we applied tACS over the dominant cerebellar hemisphere during the execution of three different motor tasks: 1) standing (both with eyes open and closed); 2) gait initiation (assessed both for the dominant and non-dominant lower limb); 3) 5-meter walk test (5MWT) (Fig. 1). tACS was delivered in a random order at the theta (5 Hz, theta-tACS) and gamma (50 Hz, gamma-tACS) frequencies, and sham-tACS was used as a control condition. The stimulation intensity was set at 1,5 mA and the stimulation duration lasted as long as the motor task was accomplished. Kinematic data were obtained using a force platform and an optoelectronic system. The data analysis was conducted using a dedicated software. Theta-tACS induced a significant reduction of the Centre Of Pressure (COP) displacement during standing with eyes closed compared to sham- and gamma-tACS (mean radius displacement: theta- tACS 4.65±0.74 mm, gamma-tACS 5.58±1.26 mm, sham-tACS 5.99±2.12 mm). A similar, though weaker, trend was present in the eyes open condition. Furthermore, stride width during 5MWT resulted tighter during theta-tACS compared to sham- and gamma tACS. Boosting theta oscillations in the cerebellum through tACS improves balance during standing and gait in healthy subjects. This effect may rely on the modulation of the activity of cerebellar neurons resonant to the theta rhythm. This non-invasive neuromodulation approach could be applied in neurological conditions characterized by ataxia to possibly ameliorate the imbalance and reduce the risk of falling.

Responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects

PurposeTo compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects. ScopeNine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions. ResultsPerturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait. ConclusionsHealthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.

Measures of dynamic balance during level walking in healthy adult subjects: Relationship with age, anthropometry and spatio-temporal gait parameters.

The maintenance of balance in dynamic conditions (e.g. during walking) is a necessary requirement that motor control must reach to avoid falls. However, this is a challenging situation, since to ensure the forward progression of the body, the center of mass must stay outside the base of support in the sagittal plane, and simultaneously remain inside the lateral borders in the frontal plane. Deviation from normative data of healthy subjects in dynamic balance could be used to quantify gait stability, fall risk and to provide hints for rehabilitation. However, normative data can be influenced by age, sex, anthropometry and spatio-temporal gait parameters, and such differences among subjects and leg side can hamper accurate assessment. The aims of this study were to investigate, in a group of healthy subjects: (1) possible asymmetry in dynamic balance maintenance strategies between leg sides, (2) the influence of age, sex and anthropometry on stability and (3) its dependence by spatio-temporal gait parameters. A total of 34 healthy subjects aged between 21 and 71 years, and ranging from 50.1 to 101.6 kg of body mass and from 155.0 to 188.9 cm of height were assessed on spatio-temporal and dynamic balance parameters (Foot Placement Estimator at heel strike and Margin of Stability at mid-stance) during self-selected gait. No parameter showed differences between legs. Dynamic balance parameters were influenced by sex, age, body mass and height mainly in the frontal plane. These measures were also correlated with gait speed and stride length both in the antero-posterior and medio-lateral directions. In addition also cadence and step width influenced the stability in the sagittal and frontal planes, respectively. The findings of this study confirm the symmetry in motor control of dynamic balance during self-selected gait in healthy subjects. Sex, anthropometry and spatio-temporal gait parameters have a significant effect on stability parameters, and this should be taken into account in dynamic balance studies.

Hip-Knee-Ankle (HKA) angle modification during gait in healthy subjects

BackgroundAchieving a neutral static Hip-Knee-Ankle angle (sHKA) measured on radiographs has been considered a factor of success for total knee arthroplasty (TKA). However, recent studies have shown that sHKA seems to have no effect on TKA survivorship. sHKA is not representative of the dynamic loading occurring during gait, unlike the dynamic HKA (dHKA). Research questionThe primary objective was to see if the sHKA is predictive of the dynamic HKA (dHKA). A secondary objective was to document to what degree the dHKA changes during gait. MethodsWe analysed 3D knee kinematics during gait of a cohort of 90 healthy individuals with the KneeKG™ system. dHKA was calculated and compared with sHKA. Knees were considered “Stable” if the dHKA remained in valgus or varus for greater than 95% of the corresponding phase, and “Changer” otherwise. Patient characteristics of the Stable and Changer knees were compared to find associated factors. ResultsAbsolute variation of dHKA during gait was 10.9 ± 5.3° for the whole cohort. The variation was less for the varus knees (10.3 ± 4.8°), than for the valgus knees (12.8 ± 6.1°, p = 0.008). We found low to moderate correlations (r = 0.266 to 0.553, p < 0.001) between sHKA and dHKA values for varus knees and no significant correlation for valgus knees. Twenty two percent (36/165) of the knees were considered Changers. The proportion of knees that were Changers was 15% of the varus versus 39% of the valgus (p < 0.001). SignificanceLower limb radiographic measures of coronal alignment have limited value for predicting dynamic measures of alignment during gait.

Simulating Hemiparetic Gait in Healthy Subjects Using TPAD With a Closed-Loop Controller.

Hemiparetic gait is abnormal asymmetric walking, often observed among patients with cerebral palsy or stroke. One of the major features of asymmetric gait is excessive reliance on the healthy leg, which results in improper load shift, slow walking speed, higher metabolic cost, and weakness of the unused leg. Hence, clinically it is desirable to promote gait symmetry to improve walking. While there are no clear methods to achieve this goal, we are exploring new methods where we guide the pelvis to change the gait symmetry. This controller is designed to mimic the hands of a physical therapist holding the pelvis and guiding it to promote the usage of both legs during walking. In this paper, we show that the essence of this method can be demonstrated by promoting asymmetry in the gait of healthy subjects when walking with the device. The results showed that their kinematics and kinetics changed asymmetrically during the intervention. Subjects demonstrated asymmetric lateral ground reaction force to compensate for the lateral forces applied on the pelvis. Muscle activities increased on the targeted leg show the forced use of the leg which can be used for rehabilitation of patients with an asymmetric gait.

Reliability of pressure insoles to assess normal ground reaction forces during gait of healthy people

Objective Pressure insoles are developed to be placed in the shoes and provide embedded measurement of the pressure or/and normal ground reaction forces (NGrF). Recently, Pedoped® insoles were commercialized and consists in only one sensor providing NGrF in real-time biofeedback. As NGrF represents about 90% of ground reaction forces during gait, this device permits to record the lower limb loading during walking, standing or in other daily living activities. Thus, these insoles could be a useful tool in rehabilitation when dealing with gait asymmetry or load recovery. As the first step to evaluate the reliability of these insoles, the accuracy of NGrF measurement with Pedoped® insoles was assessed during gait of healthy subjects. Material/patients and methods Five healthy subjects were recruited. All subjects were wearing the same shoes with Pedoped® insoles placed inside. Data collection was carried out in a motion capture laboratory equipped with 4 AMTI® force platforms (PFF). Subjects were asked to stamp each foot on a PFF during one minute at self-selected speed. PFF and insoles data were synchronized by detecting the first NGrF above 20 N for the two systems. About sixty cycles were considered per insole to compare NGrF to PFF measurements. The mean error on NGrF over all cycles and insoles was computed and normalized by the maximum NGrF. Bland-Altman plots, RMSE and NRMSE, as well as Pearson correlation coefficient were computed. Results A mean error on NGrF of 31.7 N (SD: 31.9 N) was obtained between insoles and PFF. It corresponds to 3.6% (± 3.7%) of maximum NGrF during stamping. RMSE and NRMSE were of 45.4 N and 5.2% respectively. A 0.99 correlation coefficient was obtained. Bland-Altman plots highlighted that the higher the NGrF the higher the error. Discussion, conclusion Results suggested that the insoles are reliable compared to force platforms. However, highest errors seemed to be associated to calibration issues. Thus, more works must be conducted to evaluate their reliability in long time use, to estimate the intra and interoperator error, and to set up a validated protocol with injured patients. However the biofeedback of NGrF in real time with these embedded sensors open perspectives in rehabilitation.

The effects of walking speed on upper body kinematics during gait in healthy subjects

Patients undergoing a clinical gait analysis often walk slower than healthy people. However, data on how speed affects upper body movements, especially of the arms and shoulders, are scarce. Therefore, in this descriptive study, we examined how changes in walking speed affect upper-body kinematics and aspects of intersegmental coordination between upper and lower body during overground walking in a group of healthy adult subjects. Three-dimensional gait data were collected on 20 healthy subjects (aged between 22 and 31 years) walking at six speeds ranging from extremely slow to very fast. Our results showed significant speed-related changes of upper body kinematic movement curves in three aspects, namely in amplitude (curves for shoulder flexion and abduction, elbow flexion, pelvic obliquity and rotation), timing (curves for shoulder extension and abduction, elbow extension, pelvic rotation) and curve pattern (curves for shoulder and elbow flexion, shoulder rotation, pelvic tilt). The intersegmental coordination between the thorax and pelvis and arm and leg was also affected by a change of walking speed. Our data supplement the already available data in the literature examining the effects of walking speed on lower extremity motion. Furthermore, the data can be used as a reference for both basic biomechanical and clinical gait studies. The results will help in clinical practice to differentiate between effects caused by walking speed and underlying pathology.

Assessing the asymmetry of free gait in healthy young subjects.

The purpose of this study was to derive reference values for a four-level scale intended to evaluate variation in free gait asymmetry measurements in healthy subjects. This evaluation is based on kinetic values for the left and right lower limbs during gait, registered with advanced measurement systems and assessed using the symmetry index (SI) developed by Robinson. For the majority of parameters, the SI does not follow normal distribution. As such, quartile values were used to create intervals for a four-step scale of assessing symmetry of free gait in healthy subjects for each gait parameter of interest. The SI rating intervals were from 0% (very good symmetry) to 21.2% (very poor symmetry) for kinetic parameters. The poorest symmetry was observed for horizontal force F3. The four-step scale of assessing symmetry in free gait in healthy subjects can be used in diagnosing gait disorders, devising surgical treatment strategies, and monitoring the rehabilitation process. Reference values for intervals of symmetry indicators in healthy subjects can be used as criteria for comparing individuals with/without disabilities.

Development of a prototype of portable FES rehabilitation system for relearning of gait for hemiplegic subjects

This study aimed at developing a prototype of portable FES rehabilitation system for relearning gait pattern of healthy subjects, which can measure gait information during walking applying electrical stimulation for foot drop correction or providing timing information. A gait event detection method using an inertial sensor attached on the foot was determined based on gait of healthy subjects from simultaneous measurements with pressure sensors. From the result of comparing the detected gait event timings with EMG signal of the tibialis anterior muscle during walking of healthy subjects, the toe off and the foot flat timings detected by the inertial sensor were suggested to be useful to determine the stimulation timing for the foot drop correction. The gait event detection method was implemented in a prototype of portable FES rehabilitation system consisting of an 8-inch tablet-type device, 2 inertial sensors and an electrical stimulator. The portable system was examined with hemiplegic subjects under the conditions of FES foot drop correction and inducing voluntary effort to develop ankle dorsiflexion at the timing given by electrical stimulation with small stimulation intensity. The system was considered to be useful for gait rehabilitation of hemiplegia using FES foot drop correction or inducing voluntary effort.

Kinematic and Spatio-Temporal Characteristics of Gait in Blind Individuals

Introduction: Visual inputs in the neuromuscular response process of the central nerve system have an important role in various motor tasks. The identification of the influence of lack of visual input on gait in blind people may be useful in rehabilitation planning and correction of gait pattern. The aims of this study were to compare spatio-temporal variables and the symmetry index of gait among blind and healthy individuals, and investigate the effects of closing the eyes on kinematics of gait in healthy subjects. Materials and Methods: In the present study, 10 blind and 10 healthy subjects with similar age, height, and mass participated. Spatio-temporal variables of gait were measured in blind subjects without a cane and in normal subjects with and without vision. The differences between the two groups and the two walking conditions were determined through repeated measure and significance level of P < 0.05. Results: Stride length, step length, and gait velocity were lower in blind individuals than healthy individuals with vision (P < 0.05). Stride length, step length, and stride time in healthy individuals without vision were greater than in blind individuals. In healthy individuals without vision, stride and step time, fluctuation time, and single support time were increased while cadence was decreased. Moreover, the asymmetry index in the healthy group without vision in terms of variables of single support time, fluctuation time, and toe raised off the ground time had greater symmetry than the blind subjects. Conclusion: Blindness is accompanied with reduced walking speed and step and stride length. Lack of vision in healthy subjects, caused increased stride time, single support time, and fluctuation time and decreased cadence. Stride length, step length, and stride time in healthy subjects without vision were greater than in blind individuals. It seems that the role of proprioceptive receptors is more pronounced in blind individuals than normal individuals.

The investigation of kinematic features of gait in healthy subjects and patients with post-stroke atactic disorders

To study spatial/temporal parameters of gait in post-stroke vestibular-atactic syndrome. Authors investigated the speed, rhythmic and angle parameters of the gait in healthy subjects (n=15) and in patients with atactic disorders in the recovery period of vertebrobasillar ischemic stroke (n=15). Physical examination with elements of anthropometry, clinical assessment of gait function with the Dynamic Gait Index, objective assessment of gait parameters using the system for 3D movement video analysis VICON Motion Capture Systems were used. There were a statistically significant decrease in the speed and pace of the gait, increase in the step duration and duration of the double support phase. The speed and rhythmic parameters of the left and right lower limb differed significantly. A delay of the moments of foot lifting from the surface was observed. Authors also revealed a decrease in the amplitude of flexion and extension in all segments of the lower limbs in the double step phase. These characteristics represent the activation of the «sitting» strategy and facilitate the objective assessment of the hyperfunction of the reactive postural synergies in patients with post-stroke atactic disorders.

Effect of posture on hip angles and moments during gait

Anterior hip pain is common in young, active adults. Clinically, we have noted that patients with anterior hip pain often walk in a swayback posture, and that their pain is reduced when the posture is corrected. The purpose of this study was to investigate a potential mechanism for the reduction in pain by testing the effect of posture on movement patterns and internal moments during gait in healthy subjects. Fifteen subjects were instructed to walk while maintaining three postures: 1) natural, 2) swayback, and 3) forward flexed. Kinematic and force data were collected using a motion capture system and a force plate. Walking in the swayback posture resulted in a higher peak hip extension angle, hip flexor moment and hip flexion angular impulse compared to natural posture. In contrast, walking in a forward flexed posture resulted in a decreased hip extension angle and decreased hip flexion angular impulse. Based on these results, walking in a swayback posture may result in increased forces required of the anterior hip structures, potentially contributing to anterior hip pain. This study provides a potential biomechanical mechanism for clinical observations that posture correction in patients with hip pain is beneficial.

Influence of two modes of visual deprivation on postural stability and gait in healthy subjects

Influence of two modes of visual deprivation on postural stability and gait in healthy subjects

Entropy in the Analysis of Gait Complexity: A State of the Art

Human gait is a non-linear complex process requiring appropriate mathematical measuring tools. Entropy is a measure that quantifies regularity in time series: the more predictable a series is the lower the entropy value. The mathematical methods used to estimate entropy have evolved over time. At present, three algorithms are the most used to study human gait complexity: the approximate entropy (ApEn), the sample entropy (SampEn), and the multi-scale entropy (MSE). Most studies on human gait complexity have been conducted on elderly subjects or subjects with specific disorders affecting gait patterns and they used ApEn; but, because of a set of conceptual errors, the ApEn is not the most appropriate algorithm for the analysis of biological signals. Very few studies use SampEn or MSE to analyze human gait variability, but they agree that these algorithms might contribute new perspectives in the analysis of human gait and that MSE seems to be the most sensitive algorithm to changes in gait in healthy subjects.

MUSCLE FORCES ADAPTATION IN ASSISTED WALKING USING A POWERED SCKAFO

In the last few years, considerable effort has been devoted to the design of active orthoses to assist human gait. However, few works address the study of muscle forces adaptation in assisted walking [Cain, 2007]. This issue is related to the well known redundancy problem in biomechanics, which is a challenging topic for dynamic simulation and control. In a previous work [Alonso, 2011], the authors used a simple approach to solve the load sharing problem in the combined actuation of the human-orthosis system, with the fundamental hypothesis that joint torques remain constant in the assisted locomotion [Kao, 2010]. The present work investigates the adaptation of muscular forces in the assisted gait of healthy subjects to validate the mentioned solution.

底屈制動短下肢装具内の踵パッドが歩行動作に及ぼす影響

本研究では健常者を対象として，底屈制動短下肢装具内の踵部分にゴムパッドを貼付することにより，歩行動作中の時間・空間的パラメータにどのような影響を及ぼしているのか検証することを目的とした．方法は直交表に割り付けた実験水準に基づきパッドを作成し，三次元動作解析装置を用いて，踵パッド付底屈制動短下肢装具装着下で歩行し，立脚初期の実験データを得た．結果として踵パッドは，面荷重によって，床反力進行方向成分に力学的作用を及ぼし，時間空間的パラメータに影響を及ぼしていた．特に荷重応答期における足関節モーメントに寄与し，体重心を前方かつ上方に推進させ歩行を円滑にし，立脚相初期の力学的作用が歩行周期全般に影響を及ぼしていることを示唆した．

TKA wear testing input after kinematic and dynamic meta-analysis: Technique and proof of concept

Abstract Simulation under conditions that respect real kinematics and dynamics of applying a load to the components can be an important instrument to predict the behaviour of new prosthesis designs and materials during the time of wear. Various studies have shown that the gait of TKA patients is different from the gait of healthy subjects. Therefore the time behaviour which is proposed in the ISO standard does not really represent the loads in TKA patients. Most of the current testing laboratories simulate continuous walking according to ISO 14°243, but neglect everyday activities. It is impossible to simulate the real movement of specific patients. Hence, a loading mode (with respect to daily activities) was determined, based on experimental studies. The length and frequency of individual loading were also defined. The testing mode includes normal walk, sitting–standing, cycling, stair climbing and walking with extra load. The device is able to perform the ISO walk as well. The simulator has been designed to reproduce the configuration of the implanted prosthesis. The simulated motion is described by periodic harmonic function, which enables setting the proper position in required time. The duration of a compound load process reflecting daily activities lasted 240 min. The compound load consists of elementary sub cycles, each of them representing one motion phase. A relaxation phase is inserted between all active movements. Several differences were observed between known experimental results and the present standard ISO 14°243.

Walking speed affects upper body movements during gait in healthy subjects

Walking speed affects upper body movements during gait in healthy subjects

The Associations Between the Dominant and Nondominant Peak External Knee Adductor Moments During Gait in Healthy Subjects: Evidence for Symmetry

Teichtahl AJ, Wluka AE, Morris ME, Davis SR, Cicuttini FM. The associations between the dominant and nondominant peak external knee adductor moments during gait in healthy subjects: evidence for symmetry. Objectives There is growing interest in the role of the knee adduction moment in the pathogenesis of knee pain and osteoarthritis. It is unclear whether the knee adduction moment is similar between the dominant and nondominant legs during locomotion. This study examined whether asymmetry exists in the peak knee adductor moments during gait in healthy adults. Design Cross-sectional study. Setting Musculoskeletal Research Centre, La Trobe University, Melbourne, Victoria, Australia. Participants Three-dimensional Vicon gait analyses were performed for 17 healthy men and women. Interventions Not applicable. Main Outcome Measures The external dominant and nondominant peak knee adduction moments during early and late stance were analyzed to determine whether any significant differences occurred between limbs. Results Peak knee adductor moments for dominant and nondominant limbs were significantly correlated during early ( R=0.61, P=0.009) and late ( R=0.72, P=0.001) stance. After adjustment for age and sex, there was an associated 0.58 ( P=0.030) and 0.98 ( P=0.009) unit increase in the peak knee adduction moment in the nondominant leg, for every 1 unit increase in the dominant leg during the early and late stance phases of gait, respectively. Further evidence for symmetry was provided by the symmetry index, which was 0.04% and 0.62% for early and late stance, respectively. Conclusions In healthy subjects, the magnitude of the dominant limb peak external knee adduction moments during stance, and in particular late stance, appears representative of the magnitude of the moment in the nondominant limb. These findings imply symmetry between these moments and may have important implications when collecting data for limb analyses among healthy subjects. Whether gait symmetry protects against the onset of unilateral (or increases the risk for bilateral) pathological joint changes will need to be confirmed longitudinally.

THE EFFECT OF RESTRICTED KNEE EXTENSION ON GAIT IN HEALTHY SUBJECTS

THE EFFECT OF RESTRICTED KNEE EXTENSION ON GAIT IN HEALTHY SUBJECTS