Gait Tasks Research Articles

Motor-cognitive interference in balance and gait tasks of increasing complexity: a fNIRS and IMUs study

Moving in real environments requires to consider not only ecological motor tasks (e.g., curvilinear walking), but also the cognitive load associated with the motor performance [1,2]. Wearable technology provides non-invasive monitoring solutions for both aspects, through inertial sensors and functional Near-Infrared Spectroscopy (fNIRS) technique. Specifically, fNIRS assesses cortical activity through the hemodynamic response of the brain [3] and can be performed while the participant freely moves in the environment [3,4]. In this context, the prefrontal cortex (PFC) is of particular interest: it regulates executive functions and has the potential to reveal crucial information related to cognitive processes and dynamic gait indices [1,3,4]. While it is well known that different motor tasks are characterized by different PFC activations, it is not clearly understood how PFC activation changes with increased complexity of balance locomotion tasks yet. Therefore, the study aims at filling this gap investigating motor-cognitive interference in balance and gait tasks of increasing difficulty. Twenty healthy young adults (11 females, 24.4±2.7 years) randomly performed four different motor tasks of 60 s each related to dynamic (linear walking, LW, and tandem walking, TW) and static (doubleleg stance, DLS, and single-leg stance, SLS) balance while wearing: i) a fNIRS brain cap (Brite 24, Artinis, The Netherlands) to measure the PFC changes in oxygenated hemoglobin (ΔO2Hb), and ii) 4 synchronized measurement units (IMUs, Opal, APDM, USA) at sternum, pelvis and both lateral malleoli to quantify gait and balance motor patterns. Repeated measures ANOVA (ΔO2Hb) and t-tests (IMUs) were computed to investigate differences among tasks. fNIRS (top panel) and IMUs (bottom panels) results are displayed in Fig. 1. As expected, more challenging motor tasks (TW and SLS) require greater PFC activation, suggesting the use of additional attentional resources during tasks of increased difficulty. In addition, motor performance suffers of tasks complexity, as clearly emerge from dynamic gait indices and postural parameters. This study lays foundation for better understanding the motor-cognitive interference in ecological gait and balance tasks.

Interventions for improving mobility after hip fracture surgery in adults.

Interventions for improving mobility after hip fracture surgery in adults.

Longitudinal Analysis Of Mobile Smartphone Application For The Assessment Of Facioscapulohumeral Muscular Dystrophy (FSHD) Gait

Facioscapulohumeral muscular dystrophy (FSHD) can be categorized as having a loss of muscular function in the torso, pelvic girdle, and legs. FSHD patient’s gait may decline over time, which could be used as a marker of disease progression. If so, this may be beneficial for potential clinical trials. PURPOSE: Evaluate gait velocity and cadence across three gait tasks using a novel smartphone application among individuals with FSHD over 6 months. METHODS: 2 (male = 1, female = 1; avg. age = 65 years) genetically confirmed FSHD1 patients completed three gait trials that required them to walk on a level surface at home 5 out of 7 days a week at two time points, 6 months apart. Patients used a custom smartphone application (FSHD Gait), installed on a smartphone (LG KG40) and secured on the lower back using a running belt, while walking. FSHD Gait application was used to take pictures of their shoes and walking environment. The first task (T1) involved walking 10 meters 12 times once each day. The second task (T2) was to walk 10 meters 6 times, with 6 trials being performed in the morning and 6 in the afternoon with a minimum of 4 hours between sessions. In the final week (T3), participants were instructed to walk for 6 minutes without any breaks. One-way ANOVAs compared the two time points while controlling for shoe type and walking surface. RESULTS: Over the course of 6 months, neither participant expressed a significant decline in gait velocity. There was no difference in gait velocity between time point one and two for T1 (PRE = 0.93 ± 0.24 m/s, POST = 0.85 ± .04 m/s; Cohen’s d = 0.27; p = 0.75), T2 (PRE = 0.93 ± 0.15 m/s, POST = 0.88 ± 0.07 m/s; Cohen’s d = 0.50, p = 0.54) or T3 (PRE = 0.94 ± 0.21 m/s, POST = 1.00 ± .09 m/s; Cohen’s d = 0.47; p = 0.63). Similarly, over the course of 6 months, neither participant expressed decline in cadence between time point one and two for T1 (PRE = 94.07 ± 4.78 steps/min, POST = 99.66 ± 6.44 steps/min; Cohen’s d = 3.36; p = 0.13), T2 (PRE = 103.71 ± 5.17 steps/min, POST = 0.85 ± 0.04 steps/min; Cohen’s d = 0.44; 0.64) or T3 (PRE = 98.74 ± .25 steps/min, POST = 86.88 ± 11.30 steps/min; Cohen’s d = 1.03; p = 0.35). CONCLUSION: FSHD Gait application can successfully collect and analyze gait for FSHD patient assessments over a 6-month period. While cadence nor velocity significantly changed, overall both metrics declined in both participants during T1 and T2.

Biomechanical Analysis Suggests Myosuit Reduces Knee Extensor Demand during Level and Incline Gait.

An FDA-approved soft wearable robot, the Myosuit, which was designed to provide hip and knee extension torque has recently been commercialized. While studies have reported reductions in metabolic costs, increased gait speeds, and improvements in clinical test scores, a comprehensive analysis of electromyography (EMG) signals and joint kinematics is warranted because the recruitment of appropriate muscle groups during physiological movement patterns facilitates effective motor learning. Here, we compared the lower limb joint kinematics and EMG patterns while wearing the Myosuit with that of unassisted conditions when performing level overground and incline treadmill gait. The level overground gait sessions (seven healthy subjects) were performed at self-selected speeds and the incline treadmill gait sessions (four healthy subjects) were performed at 2, 3, 4, and 5 km/h. In order to evaluate how the user is assisted, we conducted a biomechanical analysis according to the three major gait tasks: weight acceptance (WA), single-limb support, and limb advancement. The results from the gait sessions suggest that Myosuit not only well preserves the users’ natural patterns, but more importantly reduce knee extensor demand during the WA phase for both level and incline gait.

Stable Sparse Classifiers predict cognitive impairment from gait patterns.

BackgroundAlthough gait patterns disturbances are known to be related to cognitive decline, there is no consensus on the possibility of predicting one from the other. It is necessary to find the optimal gait features, experimental protocols, and computational algorithms to achieve this purpose.PurposesTo assess the efficacy of the Stable Sparse Classifiers procedure (SSC) for discriminating young and healthy older adults (YA vs. HE), as well as healthy and cognitively impaired elderly groups (HE vs. MCI-E) from their gait patterns. To identify the walking tasks or combinations of tasks and specific spatio-temporal gait features (STGF) that allow the best prediction with SSC.MethodsA sample of 125 participants (40 young- and 85 older-adults) was studied. They underwent assessment with five neuropsychological tests that explore different cognitive domains. A summarized cognitive index (MDCog), based on the Mahalanobis distance from normative data, was calculated. The sample was divided into three groups (young adults, healthy and cognitively impaired elderly adults) using k-means clustering of MDCog in addition to Age. The participants executed four walking tasks (normal, fast, easy- and hard-dual tasks) and their gait patterns, measured with a body-fixed Inertial Measurement Unit, were used to calculate 16 STGF and dual-task costs. SSC was then employed to predict which group the participants belonged to. The classification's performance was assessed using the area under the receiver operating curves (AUC) and the stable biomarkers were identified.ResultsThe discrimination HE vs. MCI-E revealed that the combination of the easy dual-task and the fast walking task had the best prediction performance (AUC = 0.86, sensitivity: 90.1%, specificity: 96.9%, accuracy: 95.8%). The features related to gait variability and to the amplitude of vertical acceleration had the largest predictive power. SSC prediction accuracy was better than the accuracies obtained with linear discriminant analysis and support vector machine classifiers.ConclusionsThe study corroborated that the changes in gait patterns can be used to discriminate between young and healthy older adults and more importantly between healthy and cognitively impaired adults. A subset of gait tasks and STGF optimal for achieving this goal with SSC were identified, with the latter method superior to other classification techniques.

Association of Muscle Mass, Muscle Strength, and Muscle Function with Gait Ability Assessed Using Inertial Measurement Unit Sensors in Older Women.

Aging-related muscle atrophy is associated with decreased muscle mass (MM), muscle strength (MS), and muscle function (MF) and may cause motor control, balance, and gait pattern impairments. This study determined associations of three speed-based gait variables with loss of MM, MS, and MF in older women. Overall, 432 older women aged ≥65 performed appendicular skeletal muscle, handgrip strength, and five times sit-to-stand test to evaluate MM, MS, and MF. A gait test was performed at three speeds by modifying the preferred walking speed (PWS; slower walking speed (SWS); faster-walking speed (FWS)) on a straight 19 m walkway. Stride length (SL) at PWS was significantly associated with MM. FWS and coefficient of variance (CV) of double support phase (DSP) and DSP at PWS showed significant associations with MS. CV of step time and stride time at SWS, FWS, and single support phase (SSP) at PWS showed significant associations with MF. SL at PWS, DSP at FWS, CV of DSP at PWS, stride time at SWS, and CV of SSP at PWS showed significant associations with composite MM, MS, and MF variables. Our study indicated that gait tasks under continuous and various speed conditions are useful for evaluating MM, MS, and MF.

Frequency-Domain Analysis for Accurate and Robust Gait Cycle Time Detection with Clinical Data.

Gait tasks have become a topic of increasing inter-est in biological engineering research in recent years. One way to obtain the gait cycle time (GCT) is to analyze a subject's gait acceleration signal as recorded by an inertial measurement unit (IMU) [1]. An accurate peak detection of the IMU acceleration has thus become a requirement for GCT analysis. This study proposes a detection procedure for accurately detecting the peaks in a noisy IMU acceleration signal based on a frequency-domain analysis of the acceleration.

Suppression of Axial Tremor by Deep Brain Stimulation in Patients with Essential Tremor: Effects on Gait and Balance Measures.

Background:Deep brain stimulation (DBS) of the ventralis intermedius (VIM) nucleus of the thalamus has been successful in mitigating upper limb tremor, but the effect on gait and balance performance is unclear. Here, we aim to examine the effectiveness of VIM DBS on stride length variability, sway path length, and task-relevant tremor of various body segments in essential tremor (ET).Methods:Seventeen ET individuals treated with DBS (ET DBS) and 17 age-and sex-matched healthy controls (HC) performed a postural balance and overground walking task. In separate and consecutive visits, ET DBS performed gait and balance tasks with DBS ON or OFF. The main outcome measures were sway path length, stride length variability, and tremor quantified from upper limb, lower limb, upper and lower trunk (axial) during the gait and balance tasks.Results:With DBS OFF, ET DBS exhibited significantly greater stride length variability, sway path length, and tremor during gait and balance task relative to HC. Relative to DBS OFF, DBS ON reduced stride length variability and sway path length in ET DBS. The DBS-induced reduction in stride length variability was associated with the reduction in both upper trunk tremor and upper limb tremor. The DBS-induced reduction in sway path length was associated with the reduction in upper trunk tremor.Discussion:The findings of this study revealed that VIM DBS was effective in improving gait and balance in ET DBS and that improvements in gait and postural balance were associated with a reduction of axial tremor during the tasks.Highlights:ET patients exhibit tremor in various body locations during gait and balance.DBS reduced stride length variability and sway path length.DBS-induced improvements in gait and balance were associated with reduction in axial tremor.

Analysis of Gait Sub-Movements to Estimate Ataxia Severity Using Ankle Inertial Data.

Assessment of motor severity in cerebellar ataxia is critical for monitoring disease progression and evaluating the effectiveness of therapeutic interventions. Though wearable sensors have been used to monitor gait tasks in order to enable frequent assessment, existing solutions only estimate gait performance severity rather than comprehensive motor severity. In this study, we propose a new approach that analyzes sub-second movement profiles of the lower-limbs during gait to estimate overall motor severity in cerebellar ataxia. A total of 37 ataxia subjects and 12 healthy subjects performed a 5 m walk-and-turn task with two ankle-worn inertial sensors. Lower-limb movements were decomposed into one-dimensional sub-movements, namely movement elements. Supervised regression models trained on data features of movement elements estimated the Brief Ataxia Rating Scale (BARS) and its sub-scores evaluated by clinicians. The proposed models were also compared to models trained on widely-accepted spatiotemporal gait features. Estimated total BARS showed strong agreement with clinician-evaluated scores with r2 = 0.72 and a root mean square error of 2.6 BARS points. Movement element-based models significantly outperformed conventional, spatiotemporal gait feature-based models. The proposed algorithm accurately assessed overall motor severity in cerebellar ataxia using inertial data collected from bilaterally-placed ankle sensors during a simple walk-and-turn task. Our work could support fine-grained monitoring of disease progression and patients' responses to medical/clinical interventions.

At-Home Training With a Rhythmic Video Game for Improving Orofacial, Manual, and Gait Abilities in Parkinson’s Disease: A Pilot Study

Rhythm disorders are consistently reported in Parkinson’s disease (PD). They manifest across motor domains, such as in orofacial (oral diadochokinesis), manual (finger tapping), and gait tasks. It is still unclear, however, whether these disorders are domain- and task-specific, or result from impaired common mechanisms supporting rhythm processing (general dysrhythmia). We tested the possibility that an at-home intervention delivered via a rhythmic video game on tablet improves motor performance across motor domains in PD. Patients with PD (n = 12) played at home a rhythmic video game (Rhythm Workers) on tablet, in which they finger-tapped to the beat of music, for 6 weeks. A control group (n = 11) played an active non-rhythmic video game (Tetris). A third group (n = 10) did not receive any intervention. We measured rhythmic abilities in orofacial, manual and gait motor domains, as well as rhythm perception, before and after the intervention. Patients who performed the rhythmic training improved their orofacial and manual rhythmic performance. This beneficial effect was linked to improved rhythm perception only following the rhythmic training period. We did not observe any improvement in rhythmic abilities in the other two groups. In this pilot study, we demonstrated that at-home intervention with a rhythmic video game using finger tapping can have beneficial effects on motor performance across different motor domains (manual and orofacial). This finding provides evidence of a general dysrhythmia in PD and paves the way to technology-driven interventions aiming at alleviating rhythm-related motor deficits in PD.

Young adults who improve performance during dual-task walking show more flexible reallocation of cognitive resources: a mobile brain-body imaging (MoBI) study.

In young adults, pairing a cognitive task with walking can have different effects on gait and cognitive task performance. In some cases, performance clearly declines whereas in others compensatory mechanisms maintain performance. This study investigates the preliminary finding of behavioral improvement in Go/NoGo response inhibition task performance during walking compared with sitting, which was observed at the piloting stage. Mobile brain/body imaging (MoBI) was used to record electroencephalographic (EEG) activity, 3-dimensional (3D) gait kinematics and behavioral responses in the cognitive task, during sitting or walking on a treadmill. In a cohort of 26 young adults, 14 participants improved in measures of cognitive task performance while walking compared with sitting. These participants exhibited walking-related EEG amplitude reductions over frontal scalp regions during key stages of inhibitory control (conflict monitoring, control implementation, and pre-motor stages), accompanied by reduced stride-to-stride variability and faster responses to stimuli compared with those who did not improve. In contrast, 12 participants who did not improve exhibited no EEG amplitude differences across physical condition. The neural activity changes associated with performance improvement during dual tasking hold promise as cognitive flexibility markers that can potentially help assess cognitive decline in aging and neurodegeneration.

Reliability of Smartphone Accelerometers for Measuring Gait During Data Collection Over Zoom.

This study examined whether gait data could be reliably collected by homebound participants using iPhones under online supervision. Eighteen healthy young adults met with investigators through Zoom and installed an app to record acceleration from their iPhones' accelerometers. Half of the subjects walked normally; the other half walked while spelling words backward. During the gait tasks subjects recorded their anterior-posterior (AP), medial-lateral (ML), and vertical (V) accelerations. Data collection was repeated the following week. Seven maximum and minimum peak accelerations in the AP, ML, and vertical directions associated with events in gait were determined. Significant main effects of week and direction were observed for the first and second vertical acceleration measures. Cronbach alpha values were >0.60 for all acceleration measures, but the maximum and minimum AP accelerations that showed fair to good levels of consistency. The findings suggest gait data collected inside the home setting may be of clinical use.

Changes in kinematic synergy in older adults during walking: A two-year follow-up study

BackgroundA well-controlled center of mass (CoM) in a coordinated segmental manner is required during gait. A synergy index that quantifies the strength of the synergistic control of the body segments that control the CoM can be evaluated using uncontrolled manifold (UCM) analysis. Several studies have compared the synergy index between older and younger adults; however, contradictory results have been found regarding age-related changes in the synergy index. Moreover, no study has investigated these changes longitudinally. Research questionTo evaluate age-related changes in the synergy index to control the CoM during gait in a longitudinal study. MethodsTwenty-five older adults participated at a baseline visit. The gait task at the two-year follow-up was completed by 16 older adults. Participants walked on a 6-m walkway at baseline and the two-year follow-up, and kinematic data were collected. Using UCM analysis, the synergy indices controlling CoM in the mediolateral and vertical directions were evaluated at baseline and follow-up. We also evaluated the Timed Up and Go (TUG) test and the strength of the knee extensor at both periods. ResultsWe found that TUG was significantly slower at follow-up; however, no difference was found in muscle strength. The synergy index in the mediolateral direction increased significantly after two years; such increases were found in individuals with decreased gait speed. SignificanceThis study showed that changes in gait patterns, including decreasing gait speed and increasing segmental coordination, may be important for gait with appropriate postural control relative to the environment and dynamic stability of the body in individuals with low functional mobility.

Smartphone Measured Single- and Dual-Task Gait Evaluation in Adolescents Post-Concussion: A Longitudinal Comparison to Healthy Controls

Background: Impairments in postural stability are common following concussion. However, subjectively-scored assessments of postural control, such as the Balance Error Scoring System, may not accurately reflect postural instability. Objective measures, such as gait performance, can more accurately identify ongoing impairments in postural control throughout concussion recovery. Recent technological advances make gait evaluations more feasible across different clinical settings. Purpose: To compare performance on smartphone measured single- and dual-task gait evaluations among adolescent concussion participants and healthy controls across two timepoints. Methods: We evaluated concussed participants at initial (n=13; 14.6±1.3 years; 54% female; 5.5±1.6 days post-concussion) and follow-up visits (33.2±3.3 days post-concussion), and healthy control participants (n=21; 15.5±1.6 years; 48% female) at two timepoints 27.3±0.7 days apart on single- and dual-task gait performance. Single-task gait trials consisted of walking at a self-selected pace for 20 meters. Single-task cognitive trials involved responding to a cognitive task while standing in place. For dual-task trials, participants completed gait and cognitive tasks simultaneously. During each trial a smartphone affixed to the lumbar spine measured gait velocity and cognitive response accuracy and response time. We conducted a 2x2 mixed effects ANOVA to examine changes between groups across the testing timeline. Results: Concussion participants reported significantly greater symptom severity than control participants at the initial timepoint (23.1±13.5 vs 7.4±8.5; p=0.001); however, this difference did not persist to the second timepoint (p=0.99). The concussion group demonstrated significant improvements in single-task gait velocity between timepoints; although, between-group differences in gait velocity were not observed at either timepoint (Figure 1). No differences in cognitive accuracy between groups were identified. However, concussed participants performed worse than healthy controls on cognitive response time at both time points in single- and dual-task testing (Figure 2). Further, response time improved between testing periods for single-task, but not dual-task, conditions. Conclusion: Smartphone gait evaluations indicate improvement in single-task gait velocity during concussion recovery. However, no significant differences in gait velocity were found between concussed and control participants at either time point in single- or dual-task gait conditions. Interestingly, concussion patients had slower cognitive responses than healthy controls at both time points, despite no differences in cognitive accuracy or symptom severity at time 2. Our preliminary findings suggest that smartphone gait evaluations are effective in measuring changes in gait velocity and cognitive performance following adolescent concussion, as well as detecting subtle differences in gait and cognitive performance between concussed and control patients throughout recovery. [Figure: see text][Figure: see text]

Gait variability between younger and older adults: An equality of variance analysis

BackgroundTo estimate gait variability, several methods have been routinely used which provide a measure of global variability. A recent study introduced a group waveform variability method which provides a point-by-point measurement of data variance equality. This can identify where in the gait cycle the significant differences in variability exist. Research questionDo waveform differences exist in equality of variance and group means in lower limb biomechanical variables between healthy younger and older adults during a gait task? MethodsTwenty healthy younger (19–44 years old, age=29.9(7.0) years, body mass index= 24.6(3.2)kg/m2, females= 10) and 20 healthy older (55–79 years old, age=63.6(5.5) years, body mass index= 25.9(2.7)kg/m2, females= 10) adults who were free from lower limb injuries and had no musculoskeletal or neurological disorders. Temporospatial outcomes, sagittal and frontal lower limb joint angles and moments, along with joint powers were examined as participants walked at a self-selected pace. Waveform patterns were normalized to the gait cycle and compared using equality of variance and statistical parametric mapping techniques. ResultsNo difference in walking speed existed between the younger or older groups (P > .05). The older group had greater variability (P < .05) in sagittal hip angles, as well as greater frontal ankle angle and moment variability. The younger group had significantly greater mean (P < .05) ankle power generation prior to toe-off. SignificanceThis study provided a baseline of temporal differences in variance between healthy younger and older individuals. Its findings warrant the use of the equality of variance test to compare temporal differences for a variety of populations and tasks. Older adults generally had more variability than the younger adults, with many differences occurring near the transition from double- to single-limb support. The statistical parametric mapping analysis showed that the older adults could not generate as much ankle power as the younger adults prior to toe-off.

Development of a Novel 2-Dimensional Neck Haptic Device for Gait Balance Training

Balance problems can be a major cause of falling. Existing gait balance rehabilitation devices usually have limited overground usability due to low portability. Therefore, there is need for development of a portable gait balance rehabilitation system. To fulfill this need, a wearable balance biofeedback system is proposed that utilizes a pair of novel devices to deliver 2-dimensional hybrid haptic biofeedback to the neck that is a combination of indentation and stretching of the skin corresponding to the mediolateral (ML) and anteroposterior (AP) directions, respectively. The system's functionality is demonstrated through an experiment where 14 healthy subjects and 1 stroke patient performed stance and gait tasks under various feedback conditions. Provision of feedback to healthy subjects resulted in significant improvements in two-dimensional balance under all task conditions. It is also observed that provision of feedback during more difficult tasks resulted in more significant balance improvements. Furthermore, use of the system during gait balance evaluation trials did not cause any significant change in gait speed, meaning that it does not have any detrimental effect on the user's gait. Results of the stroke subject pilot trial showed similar trends. We expect that use of the proposed system may help to improve the overground gait balance of people suffering from the after effects of diseases such as stroke.

EMG optimization in OpenSim: A model for estimating lower back kinetics in gait

Participant-specific musculoskeletal models are needed to accurately estimate lower back internal kinetic demands and injury risk. In this study we developed the framework for incorporating an electromyography optimization (EMGopt) approach within OpenSim (https://simtk.org/projects/emg_opt_tool) and evaluated lower back demands estimated from the model during gait. Kinematic, external kinetic, and EMG data were recorded from six participants as they performed walking and carrying tasks on a treadmill. For evaluation, predicted lumbar vertebral joint forces were compared to those from a generic static optimization approach (SOpt) and to previous studies. Further, model-estimated muscle activations were compared to recorded EMG, and model sensitivity to day-to-day EMG variability was evaluated. Results showed the vertebral joint forces from the model were qualitatively similar in pattern and magnitude to literature reports. Compared to SOpt, the EMGopt approach predicted larger joint loads (p<.01) with muscle activations better matching individual participant EMG patterns. L5/S1 vertebral joint forces from EMGopt were sensitive to the expected variability of recorded EMG, but the magnitude of these differences (±4%) did not impact between-task comparisons. Despite limitations inherent to such models, the proposed musculoskeletal model and EMGopt approach appears well-suited for evaluating internal lower back demands during gait tasks.

The association between heart rate behavior and gait performance: The moderating effect of frailty.

IntroductionResearch suggests that frailty not only influence individual systems, but also it affects the interconnection between them. However, no study exists to show how the interplay between cardiovascular and motor performance is compromised with frailty.AimTo investigate the effect of frailty on the association between heart rate (HR) dynamics and gait performance.MethodsEighty-five older adults (≥65 years and able to walk 9.14 meters) were recruited (October 2016—March 2018) and categorized into 26 non-frail (age = 78.65±7.46 years) and 59 pre-frail/frail individuals (age = 81.01±8.17) based on the Fried frailty phenotype. Participants performed gait tasks while equipped with a wearable electrocardiogram (ECG) sensor attached to the chest, as well as wearable gyroscopes for gait assessment. HR dynamic parameters were extracted, including time to peak HR and percentage increase in HR in response to walking. Using the gyroscope sensors gait parameters were recorded including stride length, stride velocity, mean swing velocity, and double support.ResultsAmong the pre-frail/frail group, time to peak HR was significantly correlated with all gait parameters (p<0.0001, r = 0.51–0.59); however, for the non-frail group, none of the correlations between HR dynamics and gait performance parameters were significant (p>0.45, r = 0.03–0.15). The moderation analysis of time to peak HR, demonstrated a significant interaction effect of HR dynamics and frailty status on walking velocity (p<0.01), and the interaction effect was marginally non-significant for other gait parameters (p>0.10).ConclusionsCurrent findings, for the first time, suggest that a compromised motor and cardiac autonomic interaction exist among pre-frail/frail older adults; an impaired HR performance (i.e., slower increase of HR in response to stressors) may lead to a slower walking performance. Assessing physical performance and its corresponding HR behavior should be studied as a tool for frailty screening and providing insights about the underlying cardiovascular-related mechanism leading to physical frailty.

A passive exoskeleton can assist split-belt adaptation.

An exoskeletal device can assist walking in those with gait deficits. A passive exoskeleton can be a favorable choice for local or home rehabilitation settings because it is affordable, light weight, and less complex to utilize. While there is research that investigates the effects of exoskeleton on gait research examining the effects of such devices on gait adaptation, is rare. This is important because in diseases like stroke, the ability to flexibly adapt is affected, such that functional recovery becomes difficult. The purpose of this study was to characterize gait adaptation patterns that result from exoskeleton usage during a split-belt adaptation task. Healthy young participants were randomly assigned to a unilateral exoskeleton or a no-exoskeleton group. Each participant performed the specific split-belt adaptation tasks on the treadmill, where the speed of each belt could be controlled independently. Symmetry indices of spatiotemporal variables were calculated to quantify gait adaptation. To analyze the adaptation, trials were divided into early and late adaptation. We also analyzed degree of adaptation, and transfer effects. We also measured the symmetry of the positive power generated by the individual legs during the split-belt task to determine if using exoskeleton assistance reduced power in the exoskeleton group versus the no-exoskeleton group. Use of a passive exoskeleton device altered gait adaptation during a split-belt treadmill task in comparison to the control group. Such adaptation was found to be largely restricted to the temporal domain. Changes in the gait coordination patterns consisted of both early and late adaptive changes, especially in intra-limb patterns like stance time rather than inter-limb patterns like step time. Although the symmetry of the positive power generated during the split-belt task was found to be reduced for the exoskeleton-assistance group, it was shown that this was primarily the result of increased positive power generated by the side not receiving exoskeletal assistance. An unpowered assistive device can provide a unique solution for coordinating the lower limbs during different gait tasks. Such a solution could reduce the neural burden of adaptation consequently resulting in a reduction of the mechanical burden of walking during the bilateral gait coordination task. This may be useful for accelerating gait rehabilitation in different patient populations. However, balance control is important to consider during unilateral exoskeletal assistance.

Comprehensive visualization of spinal motion in gait sequences based on surface topography.

Analysis of spinal motion is considered to be important to assess function of the human spine. Surface topography (ST) is a method to record the vertebral orientation in 3D. Such measurements can be performed in static but also in dynamic situations like gait or other motion tasks. However, dynamic ST measurements are hard to interpret due to their complexity. The main goal of this paper is to provide comprehensive visualization tools which allow a more intuitive and comprehensive interpretation n of such measurements. In particular, juxtaposition and superimposition techniques are utilized to emphasize differences in motion characteristics. The method was applied to a test series of 12 healthy volunteers walking on a treadmill at various speed levels. It could be shown that the visualization tools are helpful to compare different motion sequences including an analysis of intra- and interindividual variation. Based on these techniques, it could be shown that the profiles of vertebral orientation remain considerable constant when one person was walking at different speed levels whereas they differed substantially between the different individuals. In contrast, the motion amplitudes contained high intra- and interindividual variation, i.e. between speed levels and different test persons. In summary, the paper demonstrates that appropriate visualization tools are helpful to interpret ST measurements and cope with the complexity of these data sets. In particular, they can be used to compare different motion sequences in a more comprehensive way.