Comfortable Speed Research Articles

Validation of 3D Knee Kinematics during Gait on Treadmill with an Instrumented Knee Brace.

To test a novel instrumented knee brace intended for use as a rehabilitation system, based on inertial measurement units (IMU) to monitor home-based exercises, the device was compared to the gold standard of motion analysis. The purpose was to validate a new calibration method through functional tasks and assessed the value of adding magnetometers for motion analysis. Thirteen healthy young adults performed a 60-second gait test at a comfortable walking speed on a treadmill. Knee kinematics were captured simultaneously, using the instrumented knee brace and an optoelectronic camera system (OCS). The intraclass correlation coefficient (ICC) showed excellent reliability for the three axes of rotation with and without magnetometers, with values ranging between 0.900 and 0.972. Pearson's r coefficient showed good to excellent correlation for the three axes, with the root mean square error (RMSE) under 3° with the IMUs and slightly higher with the magnetometers. The instrumented knee brace obtained certain clinical parameters, as did the OCS. The instrumented knee brace seems to be a valid tool to assess ambulatory knee kinematics, with an RMSE of <3°, which is sufficient for clinical interpretations. Indeed, this portable system can obtain certain clinical parameters just as well as the gold standard of motion analysis. However, the addition of magnetometers showed no significant advantage in terms of enhancing accuracy.

A Domain Adaptive Convolutional Neural Network for sEMG-Based Gait Phase Recognition Against to Speed Changes

Gait phase recognition based on surface electromyography (sEMG) signals provides a human–robot interface (HRI) for rehabilitation robots. However, a high-performance deep learning model requires to be calibrated on a large amount of data and frequently recalibrated for new gait speeds, which raises a burden on users. In this article, a domain adaptive convolutional neural network (DACNN) model for sEMG-based gait phase recognition against speed changes is proposed, which only needs to be pretrained on a comfortable gait speed (C.G.) and quick recalibrated on new gait speeds. Specifically, a CNN-based backbone model (BM) is first constructed and pretrained using C.G. data. Then, a domain adaptation (DA) algorithm is applied for recalibration, which allows the BM to learn speed-invariant representation with a small amount of new speed data. Four subjects participated in the experiment and were required to walk at four gait speeds, and three BMs based on AlexNet, LeNet, and fusion-data-CNN (FDCNN) were set as architectural options. Compared with the fine-tuning (FT) and non-recalibration (NoRC) strategies, the results show that the proposed method significantly outperforms both baseline methods. By recalibrating on 6-s data, the proposed method can achieve an accuracy improvement of 1.5%–6.1% compared with FT and 58%–81% compared with NoRC. The average gait phase recognition accuracies are 58.13% for AlexNet, 81.56% for LeNet, and 81.53% for FDCNN, respectively. The average mean absolute errors for gait event identification are 48, 85, and 66 ms, respectively. These results indicate that the DACNN with low recalibration burden can improve the usability of sEMG-based pattern recognition systems.

Vibroacoustic Therapy in Parkinsonian Patients. A Complementary Approach to Improve Rehabilitation Outcome

Background: Parkinson’s Disease (PD) is a chronic progressive neurodegenerative disorder with motor and non-motor symptoms. Rehabilitation represents an adjuvant intervention to pharmacological and surgical therapy. Our study aim was to investigate the effectiveness of the Vibroacoustic Therapy (VAT) according to the Metodo Magic Music combined with conventional Training (Tr) versus Tr alone in improving motor symptoms and postural control in PD patients. Methods: Twenty-four patients with idiopathic PD were enrolled. They were randomly assigned to the Tr-VAT or the Tr group. Total intervention time was 40 min (Tr) and 60 min (Tr-VAT) 3 times a week for 3 months. Both groups carried out at baseline and follow-up clininetric scales and tests to assess clinical outcome. Speed of postural transitions and gait parameters (endurance and comfortable and fast speed) have been measured. Results: Follow-up evaluation showed in PD patients from the Tr-VAT group as compared to those from the Tr group an improvement of postural control assessed with Berg Balance Scale (p = 0.054) and Timed-Up and Go test (TUG) test (p = 0.058). Moreover, significant (p &lt; 0.05) differences between groups were found for comfortable gait speed (p = 0.004) and speed of postural changes - from right side to supine (p = 0.03), from supine to right and left side (p = 0.01), from supine to prone (p = 0.002) and supine to sitting (p = 0.005), respectively. Conclusions: Our study demonstrated the effectiveness of VAT as complementary treatment with conventional rehabilitation approaches, by improving mobility, agility and motor flexibility in PD patients.

Assessment of the 4-meter walk test test-retest reliability and concurrent validity and its correlation with the five sit-to-stand test in chronic ambulatory stroke survivors

BackgroundThe 4-meter walk test (4-MWT) is a widely used measure to assess gait speed in the elderly but has not been validated for stroke survivors to date. ObjectivesTo assess the test-retest reliability and concurrent validity of the 4-MWT compared to the 10-meter walk test (10-MWT) as a measure of gait speed in chronic post-stroke. Secondary outcome measure: to assess the correlation of both gait measures with the 5 times sit-to-stand test (5TSTS). MethodsA cross-sectional observational study was conducted. Reliability was assessed by intraclass correlation coefficient (ICC2,1), standard error of measurement (SEM) and minimal detectable change (MDC-95%). Bland & Altman analysis was used to quantify agreement between the 4-MWT and the 10-MWT. Two consecutive walking trials of the 4-MWT and 10-MWT followed by 5TSTS were performed all on the same day. A single researcher made all measurements. ResultsThirty-six chronic ambulatory post-stroke (average age 58.56 ± 11.28 years) were analyzed at their self-selected walking speed with a dynamic start. The 4-MWT showed excellent concurrent validity and test-retest reliability: ICC2.1 = 0.991 (95% CI: 0.983, 0.996); SEM= 0.032 and MDC- 95% = 0.090 m/second) with a strong positive correlation with the 10-MWT (r = 0.957, p < 0.001). The Bland & Altman analysis showed a concordance of −0.05 m/second bias (p = 0.039) (95% limits of agreement: 0.20 to −0.29 m/second). The paired t-test showed no statistically significant difference in the mean of both walking tests (p < 0.091). However, there was only moderate correlation between the two gait assessments and the 5TSTS. ConclusionsThis study indicates excellent test-retest reliability concurrent validity and strong correlation between 4-MWT and 10-MWT with a dynamic start at comfortable speed. The 4-MWT could be used as a measure of gait speed in both outpatients and home settings in chronic ambulatory stroke survivors.

Using Motor Tempi to Understand Rhythm and Grammatical Skills in Developmental Language Disorder and Typical Language Development.

Children with developmental language disorder (DLD) show relative weaknesses on rhythm tasks beyond their characteristic linguistic impairments. The current study compares preferred tempo and the width of an entrainment region for 5- to 7-year-old typically developing (TD) children and children with DLD and considers the associations with rhythm aptitude and expressive grammar skills in the two populations. Preferred tempo was measured with a spontaneous motor tempo task (tapping tempo at a comfortable speed), and the width (range) of an entrainment region was measured by the difference between the upper (slow) and lower (fast) limits of tapping a rhythm normalized by an individual's spontaneous motor tempo. Data from N = 16 children with DLD and N = 114 TD children showed that whereas entrainment-region width did not differ across the two groups, slowest motor tempo, the determinant of the upper (slow) limit of the entrainment region, was at a faster tempo in children with DLD vs. TD. In other words, the DLD group could not pace their slow tapping as slowly as the TD group. Entrainment-region width was positively associated with rhythm aptitude and receptive grammar even after taking into account potential confounding factors, whereas expressive grammar did not show an association with any of the tapping measures. Preferred tempo was not associated with any study variables after including covariates in the analyses. These results motivate future neuroscientific studies of low-frequency neural oscillatory mechanisms as the potential neural correlates of entrainment-region width and their associations with musical rhythm and spoken language processing in children with typical and atypical language development.

Effects of specialist care lower limb orthoses on personal goal attainment and walking ability in adults with neuromuscular disorders.

Lower limb orthoses intend to improve walking in adults with neuromuscular disorders (NMD). Yet, reported group effects of lower limb orthoses on treatment outcomes have generally been small and heterogeneous. We propose that guideline-based orthotic care within a multidisciplinary expert setting may improve treatment outcomes. To examine the effectiveness of specialist care orthoses compared to usual care orthoses on personal goal attainment and walking ability. Cohort study. Adults with NMD who experienced walking problems due to calf and/or quadriceps muscle weakness and were provided with a specialist care lower limb orthosis between October 2011 and January 2021. Three months after provision, the specialist care orthosis was compared to the usual care orthosis worn at baseline in terms of personal goal attainment (Goal Attainment Scaling (GAS)), comfortable walking speed (m/s), net energy cost (J/kg/m) (both assessed during a 6-minute walk test), perceived walking ability and satisfaction. Sixty-four adults with NMD were eligible for analysis. The specialist care orthoses comprised 19 dorsiflexion-restricting ankle-foot orthoses (AFOs), 22 stance-control knee-ankle-foot orthoses (KAFOs) and 23 locked KAFOs. Overall, 61% of subjects showed a clinically relevant improvement in GAS score. Perceived safety, stability, intensity, fear of falling and satisfaction while walking all improved (p≤0.002), and subjects were satisfied with their specialist care orthosis and the services provided. Although no effects on walking speed or net energy cost were found in combined orthosis groups, specialist care AFOs significantly reduced net energy cost (by 9.5%) compared to usual care orthoses (from mean (SD) 3.81 (0.97) to 3.45 (0.80) J/kg/m, p = 0.004). Guideline-based orthotic care within a multidisciplinary expertise setting could improve treatment outcomes in adults with NMD compared to usual orthotic care by improvements in goal attainment and walking ability. A randomized controlled trial is now warranted to confirm these results.

Safe, Efficient, and Comfortable Autonomous Driving Based on Cooperative Vehicle Infrastructure System.

Traffic crashes, heavy congestion, and discomfort often occur on rough pavements due to human drivers' imperfect decision-making for vehicle control. Autonomous vehicles (AVs) will flood onto urban roads to replace human drivers and improve driving performance in the near future. With the development of the cooperative vehicle infrastructure system (CVIS), multi-source road and traffic information can be collected by onboard or roadside sensors and integrated into a cloud. The information is updated and used for decision-making in real-time. This study proposes an intelligent speed control approach for AVs in CVISs using deep reinforcement learning (DRL) to improve safety, efficiency, and ride comfort. First, the irregular and fluctuating road profiles of rough pavements are represented by maximum comfortable speeds on segments via vertical comfort evaluation. A DRL-based speed control model is then designed to learn safe, efficient, and comfortable car-following behavior based on road and traffic information. Specifically, the model is trained and tested in a stochastic environment using data sampled from 1341 car-following events collected in California and 110 rough pavements detected in Shanghai. The experimental results show that the DRL-based speed control model can improve computational efficiency, driving efficiency, longitudinal comfort, and vertical comfort in cars by 93.47%, 26.99%, 58.33%, and 6.05%, respectively, compared to a model predictive control-based adaptive cruise control. The results indicate that the proposed intelligent speed control approach for AVs is effective on rough pavements and has excellent potential for practical application.

Predictive discriminative accuracy of walking abilities at discharge for community ambulation levels at 6 months post-discharge among inpatients with subacute stroke.

[Purpose] This study aimed to compare the predictive accuracy of walking ability at discharge among subacute stroke inpatients at 6 months post-discharge in terms of community ambulation level and establish optimal cut-off values. [Participants and Methods] This prospective observational study included 78 patients who completed follow-up assessments. Patients were classified into three groups based on the Modified Functional Walking Category (household/most limited community walkers, least limited community walkers, and unlimited community walkers) obtained by telephone survey at 6 months post-discharge. Predictive accuracy and cut-off values for discriminating among groups were calculated from 6-minute walking distance and comfortable walking speed measured at the time of discharge using receiver operating characteristic curves. [Results] Between household/most limited and least limited community walkers, 6-minute walking distance and comfortable walking speed offered similar predictive accuracy (area under the curve, 0.6-0.7), with cut-off values of 195 m and 0.56 m/s, respectively. Between least limited and unlimited community walkers, the areas under the curve were 0.896 for 6-minute walking distance and 0.844 for comfortable walking speed, with cut-off values of 299 m and 0.94 m/s, respectively. [Conclusion] Walking endurance and walking speed among inpatients with subacute stroke provided superior predictive accuracy for unlimited community walkers at 6 months post-discharge.

Normal gait speed varies by age and sex but not by geographical region: a systematic review.

What are comfortable gait speed values for apparently healthy adults? How do these differ by age group, sex and geographical region? Systematic review of observational studies with meta-analysis. Apparently healthy, community-dwelling adults who have undergone measurement of comfortable gait speed. Potentially relevant studies were identified in four databases. Extracted data from studies that satisfied the eligibility criteria were added to a database containing the same information from a meta-analysis published a decade ago. The weighted mean comfortable gait speed was calculated along with the 95% confidence interval for each stratum of age/sex using a random-effects model. Mean gait speeds were further stratified by the continent where the study took place. Tests of homogeneity included I2 and prediction intervals. Meta-analysis of data from 51,248 apparently healthy adults was stratified by age (in decades) and sex. Male gait speed slowed beyond age 50 years whereas female gait speed slowed beyond age 30 years. The weighted mean gait speed ranged from 97 cm/s (females aged ≥ 80 years) to 140 cm/s (males aged 40 to 49 years). The I2 values ranged from 0 to 34.07; prediction interval ranges varied from a low of 30 (125 to 155 cm/s; males aged 40 to 49 years) to a high of 77 (83 to 160 cm/s; females aged 60 to 69 years). There was considerable overlap in confidence intervals between continents for each sex/age group. Comfortable gait speed slowed through the adult years, but males maintained a faster walking speed than females. Further stratification of comfortable gait speed by geographical region is not warranted.

Relative and absolute reliability of gait variables obtained from gait analysis with trunk acceleration in community-dwelling individuals with chronic stroke: a pilot study.

[Purpose] This pilot study aimed to investigate the relative and absolute reliability of variables obtained from an acceleration-based gait analysis conducted at comfortable and maximal gait speeds in individuals with chronic stroke. [Participants and Methods] This study included 25 community-dwelling individuals with chronic stroke. The participants wore triaxial accelerometers, while an observed walking trial was performed at comfortable and maximal speeds on two separate days 1 week apart. Relative reliability was evaluated using the intraclass correlation coefficient, and absolute reliability was evaluated using the Bland-Altman analysis, standard error of measurement, and minimal detectable change. [Results] The intraclass correlation coefficient of gait varied according to the acceleration-based gait analysis, ranging from 0.70 to 0.99. The Bland-Altman analysis revealed no systematic bias in both comfortable and maximal gait speed conditions. Most of the minimal detectable changes were smaller at maximal gait speed than at comfortable gait speed. [Conclusion] Acceleration-based gait analysis is a reliable method, particularly in maximal gait speed conditions. It may be used to assess the effect of rehabilitation interventions in individuals with chronic stroke.

脳卒中片麻痺患者の屋外活動可否に影響する運動学的因子

[Purpose] To determine the gait kinematic factors, from the pre-swing phase to the swing phase, that influence the ability of hemiplegic stroke patients to perform outdoor activities. [Participants and Methods] Using the Functional Ambulation Classification of the Hospital at Sagunto, thirty-five hemiplegic stroke patients were included in this study. They were divided into groups according to their ability to perform outdoor activities. A motion analysis device with an inertial sensor was used to measure 10-m walking at a comfortable speed. Kinematic factors were calculated from the pre-swing to the swing phase, and the groups were compared by analysis of covariance using walking speed as the covariate. [Results] The angle of knee flexion and peak angular velocity of ankle plantar flexion during toe-off of the outdoor group were significantly higher those of the indoor group. [Conclusion] The results suggest that push-off with plantar flexion of the ankle joint and the associated knee flexion angle are important for enabling hemiplegic stroke patients to engage in outdoor activities.

Lower-limb sagittal joint angles during gait can be predicted based on foot acceleration and angular velocity.

Continuous monitoring of lower-limb movement may help in the early detection and control/reduction of diseases (such as the progression of orthopedic diseases) by applying suitable interventions. Therefore, it is invaluable to calculate the lower-limb movement (sagittal joint angles) while walking daily for continuous evaluation of such risks. Although cameras in a motion capture system are necessary for calculating lower-limb sagittal joint angles during gait, the method is unrealistic considering the setting is difficult to achieve in daily life. Therefore, the estimation of lower-limb sagittal joint angles during walking based on variables, which can be measured using wearable sensors (e.g., foot acceleration and angular velocity), is important. This study estimates the lower-limb sagittal joint angles during gait from the norms of foot acceleration and angular velocity using machine learning and validates the accuracy of the estimated joint angles with those obtained using a motion capture system. Healthy adults (n = 200) were asked to walk at a comfortable speed (10 trials), and their lower-limb sagittal joint angles, foot accelerations, and angular velocities were obtained. Using these variables, we established a feedforward neural network and estimated the lower-limb sagittal joint angles. The average root mean squared errors of the lower-limb sagittal joint angles during gait ranged between 2.5°-7.0° (hip: 7.0°; knee: 4.0°; and ankle: 2.5°). These results show that we can estimate the lower-limb sagittal joint angles during gait using only the norms of foot acceleration and angular velocity, which can help calculate the lower-limb sagittal joint angles during daily walking.

Ankle Exoskeleton Assistance can Affect Step Regulation during Self-Paced Walking.

Exoskeleton assistance can reduce metabolic cost and increase preferred walking speed in unimpaired and impaired groups, but individual outcomes are highly variable. Assistance may influence step regulation, leading to individual modulation of gait variability, energetic cost, and balance control. In this study, we aimed to understand the effects of a powered ankle exoskeleton on step regulation and its relationship to self-selected walking speed, cost of transport, and gait variability. We asked 12 unimpaired young adults to walk at their comfortable walking speed on a self-paced treadmill in their regular shoes, with the exoskeleton tracking zero torque, and in two trials using proportional myoelectric control. We measured preferred walking speed, cost of transport (COT), mean and standard deviation of gait parameters, (step length, step time, and step width) and computed long-term correlations via detrended fluctuation analysis (DFA). In all exoskeleton trials, subjects walked significantly slower than in their shoes. However, the COT was equivalent between shoes and both proportional myoelectric control trials. Subjects also increased medio-lateral balance control by increasing their mean step width and reducing both short-term variability and long-term auto-correlation for this parameter. In the second powered trial subjects returned to the levels of control over step width exhibited during regular shoe walking. During the unpowered condition subjects showed a significant association between step width regulation, walking speed, and COT. However, these parameters were not significantly associated when the assistance was turned on. Together, these results demonstrate that the response to assistance is closely related to the stepping strategy, especially in the initial stages of learning.

Muscle strength and spatiotemporal gait parameters in people with Parkinson´s disease. A pilot study.

Muscle weakness in persons with Parkinson disease (PD) has been frequently recognized as a nonspecific symptom. In other neurological conditions, lower limb weakness, specifically quadriceps weakness, is the factor that causes greater gait disability. Little research has evaluated the relationship between lower limb muscle strength, using objective tools, in PD persons and gait performance. The aim of this study was to analyze the correlation between lower limb muscle strength, using an isokinetic dynamometer, and the spatiotemporal gait parameters in PD, compared with age- and sex- matched healthy controls. The study was conducted with 7 persons with PD -Hoehn and Yahr (HY) between II-III- and 7 healthy controls. Isokinetic knee and ankle tests at 60 and 120°/s and the 10-meter walking test at comfortable and fast walking speed, were performed on all recruited subjects. Significant differences in lower limb strength-related measures and gait parameters were observed between persons with PD and controls. Gait parameters showed excellent correlations (rho = 0.7) for both lower limb: ankle plantar flexion work/body wearing at 180°/s with number of steps (indirect) and stride (direct) at both speeds, and between the ankle plantar flexion peak torque/ body wearing at 180°/s with number of steps (indirect) and stride (direct) at maximum speed; and between knee extension work/body wearing at 60°/s) with stride (direct) at self-selected speed. Persons with PD (HY II-III stages) lower limb muscle strength correlates excellently with gait pattern, showing lower isokinetic strength than healthy subjects of the same age and sex. This protocol showed safety to be performed in a larger sample.

The contribution of walking speed versus recent stroke to temporospatial gait variability

BackgroundInconsistent results have been reported for temporospatial gait variability after stroke. Given the large differences in gait speed across stroke subjects and relative to healthy controls, it is not clear which changes in temporospatial gait variability can be ascribed to the walking speed during gait evaluation versus the consequences of stroke. Research questionsDoes temporospatial gait variability differ between (1) stroke subjects grouped in clinically-relevant functional ambulation classes, (2) the paretic and non-paretic legs within each class, and (3) stroke and healthy subjects after controlling for gait speed? MethodsStroke subjects were evaluated at their comfortable speed < 2 months post-onset and classified into the household (<40 cm/s, n = 38), limited-community (40–80 cm/s, n = 35), and full-community (>80 cm/s, n = 14) walkers. Coefficients of variation (CVs) for paretic and non-paretic stance, initial double-support, and single-support times, step length, step cadence, and step width were compared across the stroke ambulation classes and between the two legs. For the parameters with significantly different CVs between stroke subjects and 33 age-matched controls walking at very-slow and free speeds, a 1-way ANCOVA was used with the gait speed as a covariate. ResultsFor most step parameters, CVs were greater in slower stroke ambulation classes except for the smaller step width CV. The differences between the paretic and non-paretic legs emerged in slower walkers only. After controlling for the gait speed, CVs of stroke subjects no longer significantly differed from controls walking at very-slow speed. With controls walking at free speed, however, CVs for the paretic and non-paretic single-support times and the non-paretic step time remained significantly different. SignificanceGait is more variable at slower speeds both in stroke subjects and healthy controls. After accounting for the free gait speed, the increased variability of only a few temporal parameters may be attributed to a recent stroke.

Study on the Cutoff Value of Backward Walking Speed to Distinguish the Mobility Deficits of Stroke Patients.

ABSTRACT BACKGROUND: Backward walking speed is an objective index to evaluate motor ability, but it is not clear whether it can screen stroke patients with mobility disorders. This study aims to test the diagnostic efficacy of backward maximum walking speed (BMWS) and backward comfortable walking speed (BCWS) on mobility defects in stroke patients and obtain the cutoff values of them. METHODS: We conducted a cross-sectional study of poststroke patients who were hospitalized from July 2021 to January 2022. 98 poststroke patients were selected for 6 functional tests and divided into the high–mobility function group and low–mobility function group by K-means cluster analysis. According to the test results of BMWS and BCWS, the receiver operating characteristic curve was drawn to determine the cutoff values and compare the diagnostic efficiency of the 2 indexes. RESULTS: The BMWS of stroke patients was 0.54 (0.29) m/s, and the BCWS was 0.37 (0.19) m/s. Receiver operating characteristic results showed that the cutoff value of BMWS for the diagnosis of mobility impairment in stroke patients was 0.3 m/s, the area under the curve was 0.95 (95% confidence interval, 0.89-0.98), the specificity was 0.86, and the sensitivity was 0.93. The cutoff value of BCWS was 0.27 m/s, the area under the curve was 0.91 (95% confidence interval, 0.84-0.96), the specificity was 0.91, and the sensitivity was 0.8. There was no significant difference between the 2 indexes in the diagnosis of mobility defects in stroke patients (P &gt; .05). CONCLUSIONS: Backward walking speed is a useful indicator for discriminating stroke patients with mobility deficits. Considering the risks associated with backward walking, BCWS can be used in clinical assessments to guide nurses in the development and implementation of rehabilitation programs.

RGB-Depth Camera-Based Assessment of Motor Capacity: Normative Data for Six Standardized Motor Tasks.

Instrumental motion analysis constitutes a promising development in the assessment of motor function in clinical populations affected by movement disorders. To foster implementation and facilitate interpretation of respective outcomes, we aimed to establish normative data of healthy subjects for a markerless RGB-Depth camera-based motion analysis system and to illustrate their use. We recorded 133 healthy adults (56% female) aged 20 to 60 years with an RGB-Depth camera-based motion analysis system. Forty-three spatiotemporal parameters were extracted from six short, standardized motor tasks-including three gait tasks, stepping in place, standing-up and sitting down, and a postural control task. Associations with confounding factors, height, weight, age, and sex were modelled using a predictive linear regression approach. A z-score normalization approach was provided to improve usability of the data. We reported descriptive statistics for each spatiotemporal parameter (mean, standard deviation, coefficient of variation, quartiles). Robust confounding associations emerged for step length and step width in comfortable speed gait only. Accessible normative data usage was lastly exemplified with recordings from one randomly selected individual with multiple sclerosis. We provided normative data for an RGB depth camera-based motion analysis system covering broad aspects of motor capacity.

Comparison of ground reaction force and marker-based methods to estimate mediolateral center of mass displacement and margins of stability during walking

Dynamic balance control during human walking can be described by the distance between the mediolateral (ML) extrapolated center of mass (XCoM) position and the base of support, the margin of stability (MoS). The ML center of mass (CoM) position during treadmill walking can be estimated based on kinematic data (marker-based method) and a combination of ground reaction forces and center of pressure positions (GRF-based method). Here, we compare a GRF-based method with a full-body marker-based method for estimating the ML CoM, ML XCoM and ML MoS. Fifteen healthy adults walked on a dual-belt treadmill at comfortable walking speed for three minutes. Kinetic and kinematic data were collected and analyzed using a GRF-based and marker-based method to compare the ML CoM, ML XCoM and ML MoS. High correlation coefficients (r > 0.98) and small differences (Root Mean Square Difference < 0.0072 m) in ML CoM and ML XCoM were found between the GRF-based and marker-based methods. The GRF-based method resulted in larger ML XCoM excursion (0.0118 ± 0.0074 m) and smaller ML MoS values (0.0062 ± 0.0028 m) than the marker-based method, but these differences were consistent across participants. In conclusion, the GRF-based method is a valid method to determine the ML CoM, XCoM and MoS. One should be aware of higher ML XCoM and smaller ML MoS values in the GRF-based method when comparing absolute values between studies. The GRF-based method strongly reduces measurement times and can be used to provide real-time CoM-CoP feedback during treadmill gait training.

Between-day reliability and minimum detectable change of the Conventional Gait Model 2 and Plug-in Gait Model during running

BackgroundThe Plug-in Gait model (PiG) is commonly used in 3D motion analysis but has limited reliability. Although an improved version of PiG has been developed, called the Conventional Gait Model 2 (CGM2), there is limited evidence on its between-day reliability for running. Research questionWhat is the between-day intraclass correlation coefficient (ICC3,k) and minimum detectable change (MDC) of lower limb kinematics and kinetics for CGM2 during running and does reliability differ between CGM2 and PiG. MethodsTwenty-three healthy participants performed running at a comfortable speed in two identical test sessions at least 5 days apart. Lower limb kinematic and kinetic data in the three planes of motion were calculated using CGM2 and PiG. The ICC and MDC were calculated for the kinematic and kinetic parameters at initial contact and peak during the stance phase of running. ResultsCGM2 kinematics showed good-to-excellent reliability (ICC: 0.75–0.93), except for hip extension and ankle internal rotation, and less than 5° MDC (1.8°−4.9°) of the coronal and sagittal planes, except for hip extension. PiG showed poor-to-moderate reliability (ICC: −0.15 to 0.72) in the coronal and transverse planes and greater than 5° MDC (5.0°−21.8°), except for knee extension, adduction, and ankle dorsiflexion. CGM2 showed good-to-excellent reliability for peak kinetics (ICC: 0.75–0.97), except for hip internal rotation and knee extension. The ICC and MDC were higher for CGM2 than PiG, with significant differences in the coronal plane of the hip and knee joints and transverse plane of the hip joint in kinematics and in the sagittal and coronal plane of the hip and knee joints in kinetics. SignificanceThe between-day reliability of CGM2 was mostly good to excellent for lower limb kinematics and kinetics during running. We believe that CGM2 can more accurately assess kinematic differences between the coronal and transverse planes than the PiG.

Customized Textile Capacitive Insole Sensor for Center of Pressure Analysis

Center of pressure refers to the centroid of the ground reaction force vector detected underneath the walking foot, which is a summary measure representing body segment movements during human locomotion. In this study, we developed a cost-effective, lightweight insole-type textile capacitive sensor (I-TCPs) to analyze plantar pressure (PP) distribution and center of pressure (COP) trajectory. To test the accuracy of I-TCPs, the measured pressure data was compared with that of F-scan. The sensor performance test was divided into a static baseline test and a dynamic gait experiment, both at two different gait speeds self-selected by the subjects. Static gait results showed that I-TCPs were capable of recognizing PP segments at different gait speeds. Dynamic gait results showed an average RMSE of 1.29 ± 0.47 mm in COPx (mediolateral shift) and 12.55 ± 5.08 mm in COPy (anteroposterior shift) at a comfortable gait speed. The COP correlation between I-TCPs and F-scan was 0.54 ± 0.09 in COPx and 0.92 ± 0.04 in COPy in comfortable gait speed conditions, in which COPy values presented a stronger correlation. RMSE and correlation in fast gait speed conditions also showed similar results. The findings of this study can be the basis for future research, including rehabilitation engineering, developing ICT devices, and creating smart wearable sensors to improve quality of life for patients and healthy individuals.