Gait Conditions Research Articles

Learning the Cost Function for Foothold Selection in a Quadruped Robot.

This paper is focused on designing a cost function of selecting a foothold for a physical quadruped robot walking on rough terrain. The quadruped robot is modeled with Denavit–Hartenberg (DH) parameters, and then a default foothold is defined based on the model. Time of Flight (TOF) camera is used to perceive terrain information and construct a 2.5D elevation map, on which the terrain features are detected. The cost function is defined as the weighted sum of several elements including terrain features and some features on the relative pose between the default foothold and other candidates. It is nearly impossible to hand-code the weight vector of the function, so the weights are learned using Supporting Vector Machine (SVM) techniques, and the training data set is generated from the 2.5D elevation map of a real terrain under the guidance of experts. Four candidate footholds around the default foothold are randomly sampled, and the expert gives the order of such four candidates by rotating and scaling the view for seeing clearly. Lastly, the learned cost function is used to select a suitable foothold and drive the quadruped robot to walk autonomously across the rough terrain with wooden steps. Comparing to the approach with the original standard static gait, the proposed cost function shows better performance.

Kinematic Alignment in Cruciate Retaining Implants Improves the Biomechanical Function in Total Knee Arthroplasty during Gait and Deep Knee Bend.

Kinematic alignment (KA), which co-aligns the rotational axes of the components with three kinematic axes of the knee by aligning the components to the prearthritic joint lines, has been a recently introduced surgical technique. However, whether KA and cruciate retaining (CR) implants provide better biomechanical function during activities than mechanical alignment (MA) in posterior stabilized (PS) implants is unclear. We evaluated the biomechanical functions during the stance phase gait and deep knee bend, with a computer simulation and measured forces in the medial and lateral collateral ligaments and medial and lateral contact stresses in the polyethylene insert and patellar button. The forces on the medial collateral ligament in KA were lower than those in MA in both CR and PS TKA in the stance phase gait and deep knee bend conditions, whereas those on the lateral collateral ligament did not show any difference between the two surgical alignment techniques in the stance phase gait condition. The maximum contact stresses on the medial PE inserts in KA were lower than those in MA in both CR and PS TKA in the stance phase gait and deep knee bend conditions. However, the maximum contact stresses on the lateral PE inserts and the patellar button did not differ between MA and KA. The biomechanical function was superior in KA TKA than in MA TKA, and KA was more effective in CR TKA. This comparison could be used as a reference by surgeons to reduce the failure rates by using KA TKA instead of MA TKA.

Static Gait Planning Method for Quadruped Robot Walking on Unknown Rough Terrain

To enable quadruped robot to walk through unknown rough terrains without any machine vision system, a continuous static gait planning method is proposed in this paper. A algorithm for on-line terrain complexity evaluation according to touchdown times of swing feet is presented to make quadruped robot obtain the information of terrain without relying on machine vision system. Quadruped robot can obtain enough stability margin during walking process by using the proposed body trajectory planning method, and motion continuity of body can be guaranteed. In order to improve the terrain adaptability of quadruped robot, a tunable parameter is set in the body planning method, and the relationship between value of the tunable parameter and terrain complexity estimation is given to further improve terrain adaptability and energy utilization rate. With the proposed static gait generation method, quadruped robot can autonomous plan its static gait in real-time and travel over unknown rough terrains with enough stability margin. The simulation results show the correctness and effectiveness of the proposed method.

In vivo force-length and activation dynamics of two distal rat hindlimb muscles in relation to gait and grade.

Muscle function changes to meet the varying mechanical demands of locomotion across different gait and grade conditions. A muscle's work output is determined by time-varying patterns of neuromuscular activation, muscle force and muscle length change, but how these patterns change under different conditions in small animals is not well defined. Here, we report the first integrated in vivo force-length and activation patterns in rats, a commonly used small animal model, to evaluate the dynamics of two distal hindlimb muscles (medial gastrocnemius and plantaris) across a range of gait (walk, trot and gallop) and grade (level and incline) conditions. We use these data to explore how the pattern of force production, muscle activation and muscle length changes across conditions in a small quadrupedal mammal. As hypothesized, we found that the rat muscles show limited fascicle strains during active force generation in stance across gaits and grades, indicating that these distal rat muscles generate force economically but perform little work, similar to patterns observed in larger animals during level locomotion. Additionally, given differences in fiber type composition and variation in motor unit recruitment across the gait and grade conditions examined here for these muscles, the in vivo force-length behavior and neuromuscular activation data reported here can be used to validate improved two-element Hill-type muscle models.

Effects of a priority-based dual task on gait velocity and variability in older adults with mild cognitive impairment.

The purpose of this study to investigate how gait velocity and variability were affected by dual task prioritization in older adults with normal cognitive function and older adults with mild cognitive impairment (MCI). Eight older adults with MCI and eight cognitively normal older adults performed a walking task under usual walking with no dual task (usual gait), walk while counting backward from 100 by ones with no priority on task (no priority), walk and count while instructed to prioritize gait task (gait priority), and walk and count while instructed to prioritize the cognitive task (cognitive priority). The MCI group showed significantly slower walking speed than the normal group in the no priority condition, but no difference between both group in the usual gait condition, and they almost 3 times greater gait variability in the no priority condition than the normal group. For the effect of priority instructions, MCI group showed a dual-task cost to gait velocity almost 2 times higher than that of the normal group in the no priority condition, but the cost was almost three times higher in both gait and cognitive priority conditions. Although there was no interaction effect for gait variability, MCI group tended to be more influenced by dual task prioritization than the normal group. Our findings confirmed that the priority-based dual task paradigm is a valid way to assess gait characteristics of people with cognitive problems.

Walking through the looking glass: Adapting gait patterns with mirror feedback

Clinical locomotor research seeks to facilitate adaptation or retention of new walking patterns by providing feedback. Within a split-belt treadmill paradigm, sagittal plane feedback improves adaptation but does not affect retention. Representation of error in this manner is cognitively demanding. However, it is unknown in this paradigm how frontal plane feedback, which may utilize a unique learning process, impacts locomotor adaptation. Frontal plane movement feedback has been shown to impact retention of novel running mechanics but has yet to be evaluated in gait conditions widely applicable within neurorehabilitation, such as walking. The purpose of this study was to investigate the effects of frontal plane mirror feedback on gait adaptation and retention during split-belt treadmill walking. Forty healthy young adults were divided into two groups: one group received mirror feedback during the first split-belt exposure and the other received no mirror feedback. Individuals in the mirror feedback group were asked to look at their legs in the mirror, but no further instructions were given. Individuals with mirror feedback displayed more symmetric stance time during the first strides of adaptation and maintained this pattern into the second split-belt exposure when no feedback was provided. Individuals with mirror feedback also demonstrated more symmetric double support time upon returning to normal walking. Lastly, the mirror feedback also allowed individuals to walk with smaller gait variability during the final steps of both split-belt exposures. Overall, mirror feedback allowed individuals to reduce their stance time asymmetry and led to a more consistent adapted pattern, suggesting this type of feedback may have utility in gait training that targets symmetry and consistency in movement.

Intersegmental coordination patterns are differently affected in Parkinson's disease and cerebellar ataxia.

The law of intersegmental coordination (Borghese et al. 1996) may be altered in pathological conditions. Here we investigated the contribution of the basal ganglia (BG) and the cerebellum to lower limb intersegmental coordination by inspecting the plane's orientation and other parameters pertinent to this law in patients with idiopathic Parkinson's disease (PD) or cerebellar ataxia (CA). We also applied a mathematical model that successfully accounts for the intersegmental law of coordination observed in control subjects (Barliya et al. 2009). In the present study, we compared the planarity index (PI), covariation plane (CVP) orientation, and CVP orientation predicted by the model in 11 PD patients, 8 CA patients, and two groups of healthy subjects matched for age, height, weight, and gender to each patient group (Ctrl_PD and Ctrl_CA). Controls were instructed to alter their gait speed to match those of their respective patient group. PD patients were examined after overnight withdrawal of anti-parkinsonian medications (PD-off-med) and then on medication (PD-on-med). PI was above 96% in all gait conditions in all groups suggesting that the law of intersegmental coordination is preserved in both BG and cerebellar pathology. However, the measured and predicted CVP orientations rotated in PD-on-med and PD-off-med compared with Ctrl_PD and in CA vs. Ctrl_CA. These rotations caused by PD and CA were in opposite directions suggesting differences in the roles of the BG and cerebellum in intersegmental coordination during human locomotion. NEW & NOTEWORTHY Kinematic and muscular synergies may have a role in overcoming motor redundancies, which may be reflected in intersegmental covariation. Basal ganglia and cerebellar networks were suggested to be involved in crafting and modulating synergies. We thus compared intersegmental coordination in Parkinson's disease and cerebellar disease patients and found opposite effects in some aspects. Further research integrating muscle activities as well as biomechanical and neural control modeling are needed to account for these findings.

Functional balance assessment in recreational college-aged individuals with a concussion history

ObjectivesDespite evidence for increased musculoskeletal injury after concussion recovery, there is a lack of dynamic balance assessments that could inform management and research into this increased injury risk post-concussion. Our purpose was to identify tandem gait dynamic balance deficits in recreational athletes with a concussion history within the past 18-months compared to matched controls. DesignCross-sectional, laboratory study. MethodsFifteen participants with a concussion history (age: 19.7±0.9years; 9 females; median time since concussion 126 days, range 28–432 days), and 15 matched controls (19.7±1.6years; 9 females) with no recent concussion history participated. We measured center-of-pressure (COP) outcomes (velocity, path length, speed, dual-task cost) under 4 tandem gait conditions: (1) tandem gait, (2) tandem gait, eyes closed, (3) tandem gait, eyes open, cognitive distraction, and (4) tandem gait, eyes closed, cognitive distraction. ResultsThe concussion history group demonstrated slower tandem gait velocity compared to the control group (4.0cm/s difference), thus velocity was used as a covariate when analyzing COP path length and speed. The concussion history group (23.5%) demonstrated greater COP speed dual-task cost than the control group (16.3%) during the eyes closed dual-task condition. No other comparisons were statistically significant. ConclusionsThere may be subtle dynamic balance differences during tandem gait that are detectable after return-to-activity following concussion, but the clinical significance of these findings is unclear. Longitudinal investigations should identify acute movement deficits in varying visual and cognitive scenarios after concussion in comparison with recovery on traditional concussion assessment tools while also recording musculoskeletal injury outcomes.

Mild Cognitive Impairment Affects Obstacle Negotiation in Older Adults: Results from “Gait and Brain Study”

Background: Older adults with Mild Cognitive Impairment (MCI) are at higher risk of falls and injuries, but the underlying mechanism is poorly understood. Inappropriate anticipatory postural adjustments to overcome balance perturbations are affected by cognitive decline. However, it is unknown whether anticipatory gait control to avoid an obstacle is affected in MCI. Objective: Using the dual-task paradigm, we aim to assess whether gait control is affected during obstacle negotiation challenges in older adults with MCI. Methods: Seventy-nine participants (mean age = 72.0 ± 2.7 years; women = 30.3%) from the “Gait and Brain Study” were included in this study (controls = 27; MCI = 52). In order to assess the anticipatory control behaviour for obstacle negotiation, a 6-m electronic walkway embedded with sensors recorded foot prints to measure gait speed and step length variability, during early (3 steps before the late phase) and late (3 steps before the obstacle) pre-crossing phases of an ad hoc obstacle, set at 15% of participant’s height. Participants walked under single- and dual-task gait (counting backwards by 1’s from 100 while walking) conditions. Three-way mixed repeated-measures analysis of variance models examined differences in gait performance between groups when transitioning between pre-crossing phases towards an obstacle during single- and dual-task conditions. Analyses were adjusted for age, sex, years of education, lower limb function, fear of falling, medical status, depressive symptoms, baseline gait speed and executive function. Results: A significant three-way interaction among groups, pre-crossing phases and task showed that participants with MCI attenuated the gait deceleration (p = 0.02) and performed fewer step length adjustments (p = 0.03) when approaching the obstacle compared with controls while dual-tasking. These interactions were attenuated when executive function performance was added as a covariate in the adjusted statistical model. Conclusion: Older adults with MCI attenuate the anticipatory gait adjustments needed to avoid an obstacle when dual-tasking. Deficits in higher-order cognitive processing may limit obstacle negotiation capabilities in MCI populations, being a potential falls risk factor.

Study on walk step gait of quadruped robot based on the support polygon

In order to study the static gait stability of quadruped robot, moving orders based on the stability margin of the support polygon are studied. Based on the support triangle theory, using the brute force method of enumerated to compare all possible marching order, different moving orders of quadruped robot motion performance are analyzed by comparing adjusting frequency of the center gravity and stability margin. A series of simulation experiments were carried out to verify the proposed optimization method by using MATLAB and ADAMS software. Finally, the optimal step of the robot in static gait was obtained. The simulation results show that the optimal step can greatly improve the performance of the robot.

Difference scores between single-task and dual-task gait measures are better than clinical measures for detection of fall-risk in community-dwelling older adults

BackgroundAs the proportion of older adults in the population increases, so does the associated prevalence of falls, making falls the leading cause of fatal and nonfatal injuries among adults aged ≥65 years. In response, researchers and clinicians seek to develop a clinical tool that accurately predicts fall risk. These Investigations have included measures of clinical mobility and balance tests, strength, physiologically based tests, postural sway, and mean and variability of gait measures. To date, no study has concurrently explored all these measures to determine which measures, alone or in combination, emerge as the most predictive of fall risk. While there is evidence that dual-task gait conditions are sensitive indicators of fall risk, difference scores between dual-task and single-task gait conditions (DS) have not been explored. Research questionThis study included outcome measures representing diverse domains (clinical mobility and balance, strength, physiological, postural sway, and mean and variability of difference scores between dual- and single-task gait conditions) to determine the combination of measures that were the most sensitive for retrospectively classifying fallers from non-fallers. MethodsForty-two (mean: 75.8 yrs ± 3.3) community-dwelling older adults completed a comprehensive battery of 76 measures and classified into two groups based on self-report of having one or more falls in the previous year. ResultsResults suggest that 11 measures captured the salient characteristics of the total cohort (fallers (N = 27) and non-fallers (N = 15) and that five gait measures were sufficient for correctly classifying fallers and non-fallers with 92.3% sensitivity and 66.7% specificity with a total model classification of 82.9%. SignificanceThe five variables comprise mean DS of stride timing, stride width, and stride length and DS in variability for stride width and stride velocity demonstrating that difference in performance between dual-task and single-task gait trials was essential for discriminating fallers and superior to other measures.

Four-Meter Gait Speed: Normative Values and Reliability Determined for Adults Participating in the NIH Toolbox Study

ObjectivesTo establish reference values and determine test-retest reliability for usual and maximal 4-meter gait speed. DesignCross-sectional observational study. SettingOffices in 10 geographically dispersed cities in the United States. ParticipantsMen and women (N=1320), aged 18 to 85 years, enrolled in the National Institutes of Health Toolbox norming study. InterventionNot applicable. Main Outcome MeasuresSpecifically used were data from men and women who were timed over 4 meters (after a static start) while walking at their usual and maximum speeds. Norms for usual and maximum gait speed were derived using data from 1320 participants. Test-retest reliability for 164 participants was described using paired t tests, intraclass correlation coefficients (ICCs), and minimal detectable changes (MDCs). ResultsMean usual speed was 1.12 meters per second, whereas mean maximum speed was 1.61 meters per second. As a general linear model showed 4-meter gait speed to differ significantly according to gait condition (speed), sex, and age group; estimates of normal were calculated accordingly. The usual speed of 80- to 85-year-old women was lowest at 0.95 meters per second; the maximum speed of 18- to 29-year-old men was highest at 1.85 meters per second. Test-retest measures did not differ significantly, but the ICCs were only fair and the MDCs were high. ConclusionsNormative reference values provided herein may be helpful in interpreting measurements of 4-meter gait speed obtained from adult men and women. The limited reliability of the gait speed measurements, however, limits their usefulness in making judgments regarding change.

P124. Evaluation of gait parameters in functional gait disorders

Objective To identify thresholds for pathognomonic gait parameters in functional gait disorders. Background Characteristics of functional gait disorders are e.g. transient fluctuations in stance and gait, excessive slowness or hesitation that is not compatible with neurological disease, uneconomic postures with wastage of muscular energy, the ‘walking on ice’ gait pattern with typical small cautious steps with fixed ankle joints and sudden buckling of the knees that generally do not lead to falls ( Lempert et al., 1991 ). Early diagnosis is important: Over half of the patients with psychogenic disorder of stance and gait remain unchanged after five and a half years. If the disorder is present no longer than four months complete remission can often be achieved ( Brandt et al., 1994 ). Methods We used a pressure-sensitive GAITRite© carpet to assess gait analysis during eight gait conditions (three different walking speeds, two sensory and three cognitive tasks). Each of the 23 gait parameters was edited with custom software. A binary logistic regression, ROC (receiver operating characteristic) analysis and an inversed regression were performed to identify thresholds for pathological deviations from normal range. Results In the preferred speed condition, patients with functional gait disorder differed from healthy subjects in all gait parameters, particularly in velocity, spatial, and variability measures. In the cognitive dual task condition (i.e. dual task words), however, the gait parameters almost normalized, especially the variability parameters assimilate healthy subjects. Conclusion Characteristics of gait parameters of patients with functional gait disorder were similar to postural performance in patients with phobic postural vertigo (PPV; Wuehr et al., 2017 ): The dual-task effect in patients with functional gait disorder revealed that cognitive distraction led to a normalization in walking. This is typical for functional disorders and can also be observed in patients with PPV.

P31. Gait disturbance in patients with orthostatic tremor

Introduction Orthostatic tremor (OT) is a rare disorder of unclear etiology characterized by a 13–18 Hz tremor of the legs while standing with resolving symptoms during sitting or walking. OT is associated with other movement disorders such as parkinsonism, essential tremor or cerebellar disorders. Although gait disturbances are frequently described in these diseases, there is no systemic analysis of the gait disorder linked to OT. Therefore, the aim of this study is to investigate the gait performance of patients with OT assessed by a standardized sensorimotor and cognitive walking paradigm. Methods Patients with a diagnosis of primary OT were screened and included in this study after informed consent. Gait performance was investigated during 8 different walking conditions using a pressure-sensitive sensor carpet (GAITRite®). Patients walked at preferred, slow and maximum walking speeds (PS, SS, MS), during head reclination and eyes closed conditions (HR, EC) as well as calculatory, semantic and motoric dual task conditions (DTC, DTS, DTM). The gait performance of patients was compared to age-matched healthy subjects. Gait parameters were assessed by a multivariate analysis of variance. Results Eighteen patients with a diagnosis of primary OT with a mean age of 70.4 ± 5.9 years were included in the study. In all walking conditions gait velocity (p Discussion Although OT symptoms diminish during walking, we identified constant impairments of locomotion control. The gait disturbance was characterized by an increased level of a cautious gait (slow, small-stepped, increased double support phases and BOS). Moreover, we identified disturbance of gait stability (increased CV) and interlimb coordination (left-right asymmetry). The specific alterations were found in conditions with increased sensory feedback control as well as attentional cognitive gait control. This implies an impaired integration of sensory feedback, possibly due to a dysfunction of midline cerebellar structures, as cerebellar dysfunction in OT was frequently described.

Cognitive motor interference in patients with multiple sclerosis

Patients with multiple sclerosis (PwMS) present cognitive and motor dysfunction. The Cognitive Motor Interference (CMI) could have a negative impact in PmMS’ daily-life activities especially in those situations when the concomitances of these two components are crucial (e.g., walking and talking with someone, cross a traffic light). CMI have been experimentally evaluated based on a dual task paradigm. Recent studies suggest that there is some inconsistence in the literature regarding whether dual task condition differs between PwMS and healthy peers. The objectives of this study were (i) to determine the impact of the CMI in the gait of PwMS by comparing with healthy peers and (ii) to determine which clinical, cognitive and motor, parameters were more associated with dual task gait. Forty-nine PwMS and 15 healthy peers participated in this study. The evaluations were composed by a current clinical evaluation, SDMT cognitive test, visual analogue scale of fatigue and gait evaluated at self-selected and dual task (arithmetic calculations) conditions. Afterward, the dual task cost (DTC), which is the ratio between the velocities of the 2 gait conditions, was calculated. Significant differences in the cognitive and motor performances were found between PwMS and healthy groups ( P = 10 −5 ). However, in terms of DTC, no significant difference was found between groups ( P = 0.12). EDSS score was the only significant parameter able to explain the DTC variance at 8%. The gait at self-selected condition could explain 92% of the variance of the gait at dual task condition. The CMI occurs in the same proportion in both PwMS and healthy persons. Despite the preponderance of the motor component in the DTC and in gait dual task condition, a combined motor and cognitive rehabilitation approach may have better results than a rehabilitation programs based on separated components.

Balance ability and posture in postmenopausal women with chronic pelvic pain.

The aim of the present study was to analyze balance ability and posture in postmenopausal women with chronic pelvic pain (CPP). This study includes a sample of 48 women with CPP recruited from the Gynecology Service of Virgen de las Nieves and San Cecilio Hospitals in Granada (Spain) and 48 healthy control women matched with respect to age and anthropometric characteristics. Outcome variables collected included: balance ability (Mini-Balance Evaluation Systems Test and Timed Up an Go Test) and posture (photogrammetry and Spinal Mouse). Significant differences were found in all Mini Best Test subscales: total (P < 0.001), anticipatory (P = 0.002), reactive postural control (P < 0.001), sensory orientation (P < 0.001), and dynamic gait (P < 0.001), and all Timed Up and Go test subscales: alone (P < 0.001), with manual (P = 0.002) and cognitive task (P = 0.030). Significant differences were also found on spinal cervical angles with a forward head posture in women with CPP; global spine alignment exhibited more deviation in the women with CPP (P < 0.001); and a higher percentage of women with CPP (58%) presented with increased thoracic kyphosis and lumbar lordosis. Cohen's d was used to calculate the effect size. Some subscales of balance and posture tests showed a large effect size (d ≥0.8), indicating a more consistent result. Women with CPP presented poor balance including anticipatory, reactive postural control, sensory orientation, dynamic gait, and dual task-related conditions. Posture showed higher values on the dorsal angle and lower sacral inclination, less spine alignment, and a more prevalent posture with increased kyphosis and lumbar lordosis.

Dual task gait after moderate-to-severe traumatic brain injury: Characterization of troubles and consequences

Patients suffering from traumatic brain injury (TBI) often present with cognitive but also posture and gait impairments. In this study, we aimed at evaluating the cost of the addition of 3 types of cognitive concurrent tasks on gait parameters, and studying the relationship between dual task cost and patient-reported perception of their confidence in balance and gait in daily living. Spatiotemporal gait parameters were assessed using a GAITRITE mat in 22 moderate-to-severe TBI patients and 26 age-matched healthy controls. The addition of 3 cognitive tasks (letter back-task, substractions by 3, talking when walking) was studied during unobstructed walking and stepping over an obstacle. We also evaluated the relationship between dual task cost during gait and (1) cost in another motor task (Baddeley) and (2) patient perceived confidence in dynamic balance and gait in daily living (ABC scale). Dual task cost during gait was higher in TBI patients compared to healthy controls when walking unobstructed and in the subtraction and talking concurrent tasks. Alteration of gait speed was primarily due to a decrease of step length more than of gait cadence. TBI patients tended to prioritize the cognitive task. Dual task cost during gait was correlated with the Baddeley dual task performance ( r = −0.420; P = 0.003) but not with the ABC scale score. TBI patients exhibit difficulties in dual task gait conditions, which can be easily assessed and should be addressed in rehabilitation. The dual task cost could be not specific to locomotor activities. Finally, other factors seem to explain the alteration in confidence in gait and balance in daily living.

Dynamics of corticospinal motor control during overground and treadmill walking in humans.

Increasing evidence suggests cortical involvement in the control of human gait. However, the nature of corticospinal interactions remains poorly understood. We performed time-frequency analysis of electrophysiological activity acquired during treadmill and overground walking in 22 healthy, young adults. Participants walked at their preferred speed (4.2, SD 0.4 km/h), which was matched across both gait conditions. Event-related power, corticomuscular coherence (CMC), and intertrial coherence (ITC) were assessed for EEG from bilateral sensorimotor cortices and EMG from the bilateral tibialis anterior (TA) muscles. Cortical power, CMC, and ITC at theta, alpha, beta, and gamma frequencies (4-45 Hz) increased during the double support phase of the gait cycle for both overground and treadmill walking. High beta (21-30 Hz) CMC and ITC of EMG was significantly increased during overground compared with treadmill walking, as well as EEG power in theta band (4-7 Hz). The phase spectra revealed positive time lags at alpha, beta, and gamma frequencies, indicating that the EEG response preceded the EMG response. The parallel increases in power, CMC, and ITC during double support suggest evoked responses at spinal and cortical populations rather than a modulation of ongoing corticospinal oscillatory interactions. The evoked responses are not consistent with the idea of synchronization of ongoing corticospinal oscillations but instead suggest coordinated cortical and spinal inputs during the double support phase. Frequency-band dependent differences in power, CMC, and ITC between overground and treadmill walking suggest differing neural control for the two gait modalities, emphasizing the task-dependent nature of neural processes during human walking. NEW & NOTEWORTHY We investigated cortical and spinal activity during overground and treadmill walking in healthy adults. Parallel increases in power, corticomuscular coherence, and intertrial coherence during double support suggest evoked responses at spinal and cortical populations rather than a modulation of ongoing corticospinal oscillatory interactions. These findings identify neurophysiological mechanisms that are important for understanding cortical control of human gait in health and disease.

Information presentation through a head-worn display ("smart glasses") has a smaller influence on the temporal structure of gait variability during dual-task gait compared to handheld displays (paper-based system and smartphone).

The need to complete multiple tasks concurrently is a common occurrence both daily life and in occupational activities, which can often include simultaneous cognitive and physical demands. As one example, there is increasing availability of head-worn display technologies that can be employed when a user is mobile (e.g., while walking). This new method of information presentation may, however, introduce risks of adverse outcomes such as a decrement to gait performance. The goal of this study was thus to quantify the effects of a head-worn display (i.e., smart glasses) on motor variability during gait and to compare these effects with those of other common information displays (i.e., smartphone and paper-based system). Twenty participants completed four walking conditions, as a single task and in three dual-task conditions (three information displays). In the dual-task conditions, the information display was used to present several cognitive tasks. Three different measures were used to quantify variability in gait parameters for each walking condition (using the cycle-to-cycle standard deviation, sample entropy, and the “goal-equivalent manifold” approach). Our results indicated that participants used less adaptable gait strategies in dual-task walking using the paper-based system and smartphone conditions compared with single-task walking. Gait performance, however, was less affected during dual-task walking with the smart glasses. We conclude that the risk of an adverse gait event (e.g., a fall) in head-down walking conditions (i.e., the paper-based system and smartphone conditions) were higher than in single-task walking, and that head-worn displays might help reduce the risk of such events during dual-task gait conditions.

Static and dynamic plantar pressure distribution in amateur marathon runners.

The aim of the study was to compare the static and dynamic plantar pressure profiles of amateur marathon runners with sedentary cohorts. Are there differences in the plantar pressures of these two populations? Is there a correlation between body mass and BMI with plantar loading? The study involved 43 runners involved in marathon training and 30 age-matched untrained individuals. Plantar pressure was measured using a baropodometric system. The marathon runners showed greater forefoot plantar pressure of the dominant extremity in the static condition and reduced medial plantar pressure of both extremities in the dynamic condition. A correlation was observed between body mass and BMI with mean plantar pressure only in the marathon group and only for the dominant extremity in the dynamic condition. Marathon training may modify the forefoot plantar loading characteristics of the dominant extremity during static conditions and increase lateral plantar pressure of both extremities in a dynamic (gait) condition.