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Traditional clinical approaches diagnose disorders of the nervous system using standardized observational criteria. Although aiming for homogeneity of symptoms, this method often results in highly heterogeneous disorders. A standing question thus is how to automatically stratify a given random cohort of the population, such that treatment can be better tailored to each cluster9s symptoms, and severity of any given group forecasted to provide neuroprotective therapies. In this work we introduce new methods to automatically stratify a random cohort of the population composed of healthy controls of different ages and patients with different disorders of the nervous systems. Using a simple walking task and measuring micro-fluctuations in their biorhythmic motions, we show that gait is compromised in healthy aging and that in young FMR1 premutation carriers, gait forecasts, even by 15 years ahead, symptoms resembling those of elderly with Parkinson9s disease. Our methods combine non-linear causal network connectivity analyses in the temporal and frequency domains with stochastic mapping, defining a new type of internal motor timings amenable to create personalized clinical interventions. We frame our results using the principle of reafference and operationalize them using causal prediction, thus renovating the theory of internal models for the study of neuromotor control.

Freezing of gait is an episodic phenomena faced by many patients with Parkinson’s disease. It is characterized by episodes during which patients are unable to generate effective forward stepping movements, despite absence of motor deficits. During the onset of the event, the patients are less stable with statistically different stride width, toe in/out angle and center of pressure distance. It has been postulated that the degree of freezing can be reduced by providing external sensory feedback to the patients during the event. However, this intervention could be facilitated by accurate identification of freezing events in real-time. This manuscript presents an Artificial Neural Network model which uses signals recorded by an instrumented footwear to predict if a walking subject is having a freezing episode. Our model presented in this paper is capable of continuously predicting freezing of gait events at a high temporal resolution of 50 Hz, using a 0.5 second window of data recorded by the instrumented shoes, with a sensitivity of 96.0±2.5%, a specificity of 99.6±0.3%, a precision of 89.5±5.9%, and an accuracy of 99.5±0.4%. This algorithm was tested with data collected from 10 patients with Parkinson’s disease with frequent freezing of gait episodes.

This study investigates how external vertical forces on the pelvis change the stability of stairmill climbing and other gait parameters such as kinematics and muscle activity. We use a Tethered Pelvic Assist Device (TPAD) to apply forces on the pelvis during continuous ascent on a stairmill. Ten young healthy subjects participated in three one-minute stair ascent with no force, a 10% body weight (BW) downward force, and a 10% BW upward force applied on the pelvis. The stability is determined by evaluating the base of support (BoS) and margin of stability (MoS). Kinematics and muscle activities were used to characterize the biomechanical changes. The results show that the upward forces applied on the pelvis decreased the (i) MoS by 1.84cm in the lateral direction, 2.07cm in the anterior direction, (ii) double stance phase by 1.85%, and (iii) the knee flexion by 5°. Furthermore, the peak activation levels of the muscles rectus femoris (RF), vastus lateralis (VL), and left gastrocnemius decreased. In contrast, the downward forces applied on the pelvis increased (i) the MOS by 1.5cm in the anterior direction and (ii) mean activation levels of RF and VL muscles. This study provides insights into the effects of applied vertical forces on the pelvis during stair ascent. These findings contribute to the understanding of the gait parameter changes and their relation with stability. Results could be used as a basis for designing training protocols to improve balance during stair ascent.

In people with severe neuromotor deficits of trunk and lower extremities, regaining balance in standing is often performed in rehabilitation with manual assistance, rigid body supports or by the use of handrails. To investigate and further expand postural control training in standing, we developed a Robotic Upright Stand Trainer (RobUST). In this study, we used RobUST to deliver trunk perturbations while simultaneously providing postural assistive forces on the pelvis in 10 able-bodied adults. Posture control responses with 'pelvic support' was then compared to 'no support' and 'hand supported' standing, with and without assistance from RobUST. We characterize postural imbalance with kinematic displacements and center of pressure (COP) outcomes, such as amplitude and root mean square of the excursions of COP. Surface electromyography (sEMG) was also applied to investigate muscle control. We additionally investigated ground reaction and handrail forces during standing to analyze how postural strategies and muscle mechanisms with 'pelvic support' via RobUST would differ from standing with 'no support' and with the 'handrail support'. Our results show that during perturbations, pelvic assistive support decreased kinematic and COP excursions compared to standing with no support. The pelvic assistance from RobUST showed similar level of COP changes as the use of handrail support but without reducing muscle activity or ground reaction forces. As expected, the maximum level of postural stability was observed when participants used the handrail and received pelvic assistive forces. In conclusion, RobUST demonstrates potential as a training device since it enhances postural balance without significantly removing muscular control mechanisms that are of interest in re-training postural control strategies in standing.

Seated postural abilities are critical to functional independence and participation in children with cerebral palsy, Gross Motor Functional Classification System (GMFCS) levels III-IV. In this proof-of-concept study, we investigated the feasibility of a motor learning–based seated postural training with a robotic Trunk-Support-Trainer (TruST) in a longitudinal single-subject-design (13y, GMFCS IV), and its potential effectiveness in a group of 3 children (6-14y, GMFCS III-IV). TruST is a motorized-cable driven belt placed on the child’s trunk to exert active-assistive forces when the trunk moves beyond stability limits. TruST-intervention addresses postural-task progression by tailoring the assistive-force fields to the child’s sitting balance to train trunk control during independent short-sitting posture. TruST-intervention consisted of 2 training blocks of 6 2hour-sessions per block (3 sessions per week). Pelvic strapping was required in the 1(st) block to prevent falls. As primary outcomes, we used the modified functional reach test, gross motor function measure-item set (GMFM-IS), Box & Blocks, and postural kinematics. After TruST-intervention children did not require pelvic strapping to prevent a fall, improved trunk stability during reaching (baseline = 5.49cm, 1week post-training = 16.38cm, 3mos follow-up = 14.63cm, p < 0.001) and increased their sitting workspace (baseline = 127.55cm(2), 1week post-training, = 409.92cm(2), 3mos follow-up = 270.03cm(2), p < 0.001). Three children also improved in the GMFM-IS. In summary, our novel robotic TruST-intervention is feasible and can effectively maximize functional independent sitting in children with CP GMFCS III-IV.

Individuals with chronic hemiparesis post-stroke exhibit gait impairments that require functional rehabilitation through training. Exoskeletal robotic assistive devices can provide a user with continuous assistance but impose movement restrictions. There are currently devices that allow unrestricted movement but provide assistance only intermittently at specific points of the gait cycle. Our design, a cable-driven active leg exoskeleton (C-ALEX), allows the user both unrestricted movement and continuous force assistance throughout the gait cycle to assist the user in new walking patterns. In this study, we assessed the ability of C-ALEX to induce a change in the walking patterns of ten post-stroke participants using a single-session training protocol. The ability of C-ALEX to accurately provide forces and torques in the desired directions was also evaluated to compare its design performance to traditional rigid-link designs. Participants were able to reach 91% ± 12% of their target step length and 89% ± 13% of their target step height. The achieved step parameters differed significantly from participant baselines ( ${p} ). To quantify the performance, the forces in each cable’s out of the plane movements were evaluated relative to the in-plane desired cable tension magnitudes. This corresponded to an error of under 2Nm in the desired controlled joint torques. This error magnitude is low compared to the system command torques and typical adult biological torques during walking (2–4%). These results point to the utility of using non-restrictive cable-driven architectures in gait retraining, in which future focus can be on rehabilitating gait pathologies seen in stroke survivors.

Virtual Reality is a versatile platform to study human behavior in simulated environments and to develop interventions for functional rehabilitation. In this work, we designed a dual-task paradigm in a virtual environment where both tasks demand motor skills. Twenty-one healthy adults (mean age: 24.1 years) participated in this study. The experiment involved three conditions - normal overground walking, catch and throw a ball while standing, and catch and throw a ball while walking overground -all in the virtual environment. We investigated the dual-task gait characteristics and their correlations with outcomes from cognitive assessments. Results show that subjects walk conservatively with smaller stride lengths, larger stride widths and stride time while catching and throwing. However, they are able to throw the balls more accurately at the target and achieve higher scores. During the dual-task throw, we observed that the participants threw more balls during the stance phase of the gait when the foot was in the terminal stance and pre-swing region. During this region, the body has forward momentum. In addition, the changes in gait characteristics during dual-task throw correlate well with outcome measures in standardized cognitive tests. This study provides a new and engaging paradigm to analyze dual-motor-task cost in a virtual reality environment and it can be used as a basis to compare strategies adopted by different population groups with healthy young adults to execute coordinated motor tasks.

Adolescent Idiopathic Scoliosis (AIS) is a spinal curvature that affects 3% of the population and disproportionately affects females. It is treated with bracing and many researchers are developing models of the torso to optimize the effectiveness of brace designs. Unfortunately, the data available to create these models is limited by the experimental methods employed. One method, in vitro spine cadaver stiffness measurements, is generally based on specimens from the elderly, which are not representative of the adolescent population. The other method, radiographic studies, can only provide a limited amount of information because of the radiation exposure that multiple images require. In this work, we present a Robotic Spine Exoskeleton (RoSE) tailored to the population in greatest need of AIS interventions–female adolescents. We use it to create a three-dimensional stiffness characterization of the torso in vivo for eight female adolescents with scoliosis and eight without this condition. The key findings include an interaction effect of DOF and torso segment on translational collinear stiffnesses, and an interaction effect of DOF and group on rotational collinear stiffnesses. We also found that the 3D coupling stiffness pattern is in line with that of the human spine, regardless of spinal deformity. Also, the magnitude of the torso stiffness for the tested population is less than that of the adult male population previously characterized. Our results provide quantitative data for torso stiffness and can be used to improve brace designs. Our methods could also be adapted as a way to customize subject-specific treatment methods, as there is a lot of variation among subjects.

An ambulatory elder with SCI, AIS C, balance deficits, and right ankle-foot-orthosis participated. RobUST-intervention comprised six 90 min-sessions of postural tasks with pelvic assistance and trunk perturbations. We collected three baselines and two 1 week post-training assessments—after the first four sessions (PT1) and after the last two sessions (PT2). We measured Berg Balance Scale (BBS), four-stage balance test (4SBT)—including a 30 s-window with and without vision—standing workspace area, and reactive balance (measured as body weight%). Kinematics, center-of-pressure (COP), and electromyography (EMG) were analyzed to compute root-mean-square-COP (RMS-COP), the margin of stability (MoS), ankle range of motion, and integrated EMG (iEMG) normalized to baseline. The Borg Rating of Perceived Exertion (BRPE), and change in the Mean Arterial Pressure (MAP) and heart rate (HR) compared with baseline were collected to address training tolerance. A 2SD-bandwidth method was selected for data interpretation. The maximum BBS was achieved (1-point improvement). In the 4SBT, the participant completed 30 s (baseline = 20 s) with reduced balance variability during semi-tandem position without vision (RMS-COP baseline = 50.32 ± 2 SD = 19.64 mm; PT1 = 21.29 mm; PT2 = 19.34 mm). A trend toward increase was found in workspace area (baseline = 996 ± 359 cm(2); PT1 = 1539 cm(2); PT2 = 1138 cm(2)). The participant tolerated higher perturbation intensities (baseline mean = 25%body weight, PT2 mean = 44% body weight), and on average improved his MoS (3 cm), ankle range of motion (4°), and gluteus medius activity (iEMG = 10). RobuST-intervention was moderate-sort of hard (BRPE = 3–4). A substantial reduction in MAP (9%) and HR (30%) were observed. In conclusion, RobUST-intervention might be effective in ambulatory SCI.

Background. High-intensity repetitive training is challenging to provide poststroke. Robotic approaches can facilitate such training by unweighting the limb and/or by improving trajectory control, but the extent to which these types of assistance are necessary is not known. Objective. The purpose of this study was to examine the extent to which robotic path assistance and/or weight support facilitate repetitive 3D movements in high functioning and low functioning subjects with poststroke arm motor impairment relative to healthy controls. Methods. Seven healthy controls and 18 subjects with chronic poststroke right-sided hemiparesis performed 300 repetitions of a 3D circle-drawing task using a 3D Cable-driven Arm Exoskeleton (CAREX) robot. Subjects performed 100 repetitions each with path assistance alone, weight support alone, and path assistance plus weight support in a random order over a single session. Kinematic data from the task were used to compute the normalized error and speed as well as the speed-error relationship. Results. Low functioning stroke subjects (Fugl-Meyer Scale score = 16.6 ± 6.5) showed the lowest error with path assistance plus weight support, whereas high functioning stroke subjects (Fugl-Meyer Scale score = 59.6 ± 6.8) moved faster with path assistance alone. When both speed and error were considered together, low functioning subjects significantly reduced their error and increased their speed but showed no difference across the robotic conditions. Conclusions. Robotic assistance can facilitate repetitive task performance in individuals with severe arm motor impairment, but path assistance provides little advantage over weight support alone. Future studies focusing on antigravity arm movement control are warranted poststroke.

Visual and force feedback are common elements in rehabilitation robotics, but visual feedback is difficult to provide in over-ground mobile exoskeleton systems. This letter aims to provide a method to integrate visual feedback using an augmented reality HoloLens headset with our mobile C-ALEX system. A preliminary study was carried out to assess the effects of providing force-only (Haptic), force and visual (HoloHapt) or visual (Visual) feedback to three independent groups, each containing eight participants. The groups showed an increase in normalized step height, nSH (HoloHapt: 1.10 $\pm$ 0.13, Haptic: 1.03 $\pm$ 0.23 Visual: 1.61 $\pm$ 0.52) and decreased normalized trajectory tracking error, TE (HoloHapt: 42.8% $\pm$ 23.4%, Haptic: 47.6% $\pm$ 18.4%, Visual: 114 .2 % $\pm$ 60.0 % ). Visual nSH differed significantly from HoloHapt and Haptic nSH ( $p ). Lap-wise normalized tracking error differed significantly ( $p ) within participants. The results show the feasibility of and differences between each form of feedback for overground gait training. This information is useful for future studies targeted at patients with gait impairments.

Objective This paper presents the first study where a dynamic neck brace was used to characterize the head motion of ALS patients while concurrently recording the surface electromyography (EMG) of the neck muscles. Methods Eleven ALS patients and 10 age‐matched healthy controls consented and participated in an experiment. Each participant was asked to perform three single‐plane motions of the head‐neck that included flexion–extension in the sagittal plane, lateral bending in the coronal plane, and axial rotation in the transverse plane. Each motion was performed in a cycle and was repeated five times at self‐selected speeds. Results During single‐plane flexion–extension under gravity, compared to healthy peers, ALS patients showed a shorter duration to reach the maximum flexion and an earlier EMG onset in the neck extensors starting from the neutral. The brace measures in activation of the neck muscles in ALS patients were well correlated with clinically measured scores, such as the ALSFRS‐r and the FVC. The activation duration of sternocleidomastoid, used to rotate the head, correlated well with the ALSFRS‐r and FVC in ALS patients during axial rotation. Interpretation The ability to synchronously activate a pair of muscles to execute single‐plane motions in ALS patients seems to have been compromised due to the disease and potentially results in head drop. The neck brace measures can be adapted in the clinic to complement self‐reporting in ALS patients and used to assess the head drop and progress of the disease.

SummaryPeople with severe neuromuscular trunk impairment cannot maintain or control upright posture of the upper body in sitting while reaching. Passive orthoses are clinically available to provide support and promote the use of upper extremities in this population. However, these orthoses only position the torso passively without any degree of trunk movement.We introduce for the first time a novel active-assistive torso brace called Wheelchair Robot for Active Postural Support (WRAPS). It consists of two rings over the hips and chest connected by a 2RPS-2UPS parallel robotic device. WRAPS can modulate the displacement of the upper ring and/or the forces applied on the torso through the ring in four degrees-of-freedom (DOF), including rotations and translation in the sagittal and frontal planes.In the present study, we evaluate the design of WRAPS and its functions. Moreover, we discuss the potential effectiveness of WRAPS as a therapeutic robotic tool in people with severe trunk control deficits. The performance of WRAPS was evaluated in seated healthy subjects. Kinematics and surface electromyography (sEMG) were collected when the participants performed selective trunk movements. First, the torso range of motion (tROM) was calculated with WRAPS in transparent mode—zero-force control mode—which was compared with free-guided tROM (no WRAPS) with motion capture system. Second, a position control mode was configured to mobilize the torso along the trajectories obtained with the transparent mode.Our results show that the design of WRAPS suited well the subject’s anthropometrics while supporting the weight of the torso. Importantly, WRAPS can be programmed to replicate the subject’s tROM, without the full activation of torso muscles. This can be critical in individuals with no trunk control. Altogether, these preliminary results indicate the potential applicability of WRAPS to promote active-assistive trunk mobility in people who cannot sit independently because of trunk dysfunction.

In a previous study, a tethered pelvic-assist device (TPAD) was used to successfully retrain crouch gait in children with cerebral palsy by applying a downward force on the pelvis while walking on a treadmill. While the results of this study were promising, an important issue was to translate this training to the children in a more practical manner. This motivated the question in this letter whether a different intervention could result in similar improvements in the gait as seen with the TPAD. This is the motivation for this study, which compares the biomechanical differences in walking under the following two conditions. 1) The TPAD applies a pure downward force on the pelvis using tethers. 2) A weighted pelvic belt is used to apply the same downward force on the pelvis. In this case, the weight belt also increases the mass at the pelvis. A total of ten healthy subjects performed two separate experiments while walking on an instrumented treadmill. The whole-body kinematics were recorded using a motion-capture system, and the ground reaction forces were measured by the force plates embedded in the treadmill. We found no significant differences in the kinematic gait parameters of healthy subjects when the downward force, equivalent to 15% body weight, applied by the TPAD was replaced by a weighted pelvic belt having 15% body weight. However, the activation of the gastrocnemius muscle and the estimated maximum ankle torque, predicted by an inverted pendulum mathematical model, during the single support phase of walking, showed a higher increase with the weight belt when compared to a pure downward force. Thus, the weight belt, because of its simplicity, must be further considered as a more convenient candidate to translate the results of TPAD in children with cerebral palsy who suffer from crouch gait.

Coordinated head–neck movement is a challenge for patients with neurological disorders, such as cerebral palsy and amyotrophic lateral sclerosis. Neck collars are commonly used to stabilize the head–neck in these patients. These collars are mostly rigid and uncomfortable to wear for extended periods of time. We have developed a robotic neck brace to assist head–neck motion. In this letter, we focus on using the robotic neck brace for training of the head-neck motion using forces applied on the head. A force controller is implemented to deliver a moment to correct the head motion in an ‘assist-as-needed’ fashion. A human study was designed to assess the performance of the robotic neck brace with the force controller. Ten young healthy adults participated in the experiment. They were asked to perform a lateral bending motion in the coronal plane of the head-neck with and without the assistance of the brace. The motions were conducted under two conditions: i) with visual feedback, ii) with visual and force feedback. We found that the rotational movement errors were significantly reduced ( $p ) during training with the force field when compared to visual feedback alone. As expected, this change was not retained during post-training. We conclude that the force controller is able to provide the desirable force assistance to help coordinate the head motion.

Aging is accompanied by an alteration in the capacity to ambulate, react to external balance perturbations, and resolve cognitive tasks. Perturbation-based balance training has been used to induce adaptations of gait stability and reduce fall risk. The compensatory reactions generated in response to external perturbations depend on the activation of specific neural structures. This suggests that training balance recovery reactions should show acute cognitive training effects. This study aims to investigate whether exposure to repeated balance perturbations while walking can produce acute aftereffects that improve proactive and reactive strategies to control gait stability and cognitive performance in healthy older adults. It is expected that an adaptation of the recovery reactions would be associated with increased selective attention and information processing speed. Twenty-eight healthy older adults were assigned to either an Experimental (EG) or a Control Group (CG). The protocol was divided in 2 days. During the first visit, all participants completed the Symbol Digit Modalities Test (SDMT) and the Trail Making Test (TMT). During the second visit, a cable-driven robot was used to apply waist-pull perturbations while walking on a treadmill. The EG was trained with multidirectional perturbations of increasing intensity. The CG walked for a comparable amount of time with cables on, but without experiencing perturbations. Before and after the training, all participants were exposed to diagonal waist-pull perturbations. Changes in gait stability were evaluated by comparing the distance between the heel of the leading leg and the extrapolated Center of Mass (Heel-XCoM Distance—HXD) at perturbation onset (PON) and first compensatory heel strike (CHS). Finally, the cables were removed, and participants completed the SDMT and the TMT again. Results showed that only the EG adapted the gait stability (p < 0.001) in reaction to diagonal perturbations and showed improved performance in the SDMT (p < 0.001). This study provides the first evidence that a single session of perturbation-based balance training produce acute aftereffects in terms of increased cognitive performance and gait stability in healthy older adults. Future studies will include measures of functional activation of the cerebral cortex and examine whether a multi-session training will demonstrate chronic effects.

Ageing, disease, and injuries result in movement defects that affect daily life. Gait analysis is a vital tool for understanding and evaluating these movement dysfunctions. In recent years, the use of virtual reality (VR) to observe motion and offer augmented clinical care has increased. Although VR-based methodologies have shown benefits in improving gait functions, their validity against more traditional methods (e.g., cameras or instrumented walkways) is yet to be established. In this work, we propose a procedure aimed at testing the accuracy and viability of a VIVE Virtual Reality system for gait analysis. Seven young healthy subjects were asked to walk along an instrumented walkway while wearing VR trackers. Heel strike (HS) and toe off (TO) events were assessed using the VIVE system and the instrumented walkway, along with stride length (SL), stride time (ST), stride width (SW), stride velocity (SV), and stance/swing percentage (STC, SWC%). Results from the VR were compared with the instrumented walkway in terms of detection offset for time events and root mean square error (RMSE) for gait features. An absolute offset between VR- and walkway-based data of (15.3 ± 12.8) ms for HS, (17.6 ± 14.8) ms for TOs and an RMSE of 2.6 cm for SW, 2.0 cm for SL, 17.4 ms for ST, 2.2 m/s for SV, and 2.1% for stance and swing percentage were obtained. Our findings show VR-based systems can accurately monitor gait while also offering new perspectives for VR augmented analysis.

Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

Hearing loss is a disabling condition that increases with age and has been linked to difficulties in walking and increased risk of falls. The purpose of this study is to investigate changes in gait parameters associated with hearing loss in a group of older adults aged 60 or greater. Custom-engineered footwear was used to collect spatiotemporal gait data in an outpatient clinical setting. Multivariable linear regression was used to determine the relationship between spatiotemporal gait parameters and high and low frequency hearing thresholds of the poorer hearing ear, the left ear, and the right ear, respectively, adjusting for age, sex, race/ethnicity, and the Dizziness Handicap Inventory&ndash, Screening version score. Worsening high and low frequency hearing thresholds were associated with increased variability in double support period. Effects persisted after adjusting for the effects of age and perceived vestibular disability and were greater for increases in hearing thresholds for the right ear compared to the left ear. These findings illustrate the importance of auditory feedback for balance and coordination and may suggest a right ear advantage for the influence of auditory feedback on gait.

Freezing of gait is an episodic phenomena faced by many patients with Parkinson’s disease. It is characterized by episodes during which patients are unable to generate effective forward stepping movements, despite absence of motor deficits. It has been postulated that the degree of freezing can be reduced by providing external sensory feedback to the patients during the event. However, this intervention could be facilitated by accurate identification of freezing events in real-time. This manuscript presents an Artificial Neural Network model which uses signals recorded by an instrumented footwear to predict if a walking subject is having a freezing episode. Our model presented in this paper is capable of continuously predicting freezing of gait events at a high temporal resolution of 50 Hz, using a 0.5 second window of data recorded by the instrumented shoes, with a sensitivity of 96.0±2.5%, a specificity of 99.6±0.3%, a precision of 89.5±5.9%, and an accuracy of 99.5±0.4%. This algorithm was tested with data collected from 10 patients with Parkinson’s disease with frequent freezing of gait episodes.

In people with severe neuromotor deficits of trunk and lower extremities, rehabilitation of standing postural control is limited to rigid body support. To expand postural control training in standing, we have recently developed a Robotic Upright Stand Trainer (RobUST). In this study, we use RobUST to deliver body perturbations on the trunk while simultaneously providing direction-specific postural assistance on the pelvis. We study the effect that assist-as-needed forces has on postural imbalance on 10 able-bodied adults. We characterize postural imbalance with center of pressure (COP) variables such as excursion and root mean square COP. Surface electromyography (sEMG) was also applied to investigate muscle strategies. RobUST was designed for future training of participants with profound postural standing deficits. A common postural strategy, applied in such population, is to encourage the use of handlebars to maintain balance. Thus, we additionally investigate COP changes during trunk perturbations when ablebodied adults stood and held a handlebar. Results show that during perturbations, pelvic assistive forces decreased postural excursions and postural variability compared to quiet standing with no support. Interestingly, participants showed a similar level of postural stability, but with fewer muscle activity, with the use of an external fixed handlebar. Although, the maximum level of postural stability was observed when participants used the handlebar and received assistive forces. Our results show a significant promise of RobUST for future training of individuals with severe postural standing deficits.

Mirror therapy, the rehabilitative technique that uses a mirroring illusion to induce cognitive responses, could benefit by performing the task in a virtual world. This research is aimed to build an effective virtual reality environment with gesture-level hand tracking and determine its viability when compared to traditional mirror therapy. A total of 24 healthy participants were recruited to perform a block stacking task in both the physical and virtual environments, with and without mirroring, using their dominant arm. Surface electromyography (sEMG) was used to measure activation of the flexor carpi radialis (FCR), extensor digitorum (ED), biceps brachii (BB) and triceps brachii (TB) in both arms. The virtual environment was shown to decrease task completion speed due to the added difficulty of control in that environment. Significant differences in muscle activity between conditions for the non-dominant arm were not achieved; however, there were significant differences in muscle activity between conditions for the dominant arm. Difficulty and weight discrepancies between the physical and virtual tasks may have contributed to this significance.

The technical development of the virtual reality platform provides multiple levels to understand human behaviors in simulated environments and to develop interventions for functional rehabilitation. In this study, a dual-task paradigm in a virtual environment is designed where both tasks demand motor skills. Three healthy adults (mean age: 24.3 years) participated in this study. The experiment involved two conditions of overground walking in virtual reality - normal walking and catch and throw a ball while walking. In this work, we investigated the dual-task gait characteristics and the strategy adopted at the lower limb to perform better in the secondary task of throwing the ball. Results show that more balls were thrown during the terminal stance and pre-swing phase of the dominant leg. Thus, the participants utilized the forward momentum built during the foot-to-foot transition by the lagging dominant foot while throwing. This study provides a new and engaging paradigm to analyze dual-motor-task in a virtual reality environment. It can be used as a powerful tool to characterize gait and cognitive performance measures in individuals.

Background The prevalence of balance and gait deficits increases with age and is associated with the increased incidence of falls seen in the elderly population; these falls are associated with significant morbidity and mortality. Objectives To review changes in gait and balance associated with aging and the effect of visual perturbations on gait and balance in the elderly to provide a basis for future research. Methods PubMed and Cochrane Library were searched for articles from 1980 to present pertaining to gait and balance in older adults (>60) and younger adults (

INTRODUCTION: Primary deficits in individuals with cerebellar degeneration include ataxia, unstable gait, and incoordination. Balance training is routinely recommended to improve function whereas little information is known regarding aerobic training. OBJECTIVE: To determine the feasibility of conducting a randomized trial comparing balance and aerobic training in individuals with cerebellar degeneration. DESIGN: Accessor blinded randomized control phase I trial SETTING: Assessments in medical center, home-training PARTICIPANTS: 20 participants with cerebellar degeneration were randomized to home balance or aerobic training. INTERVENTION: Aerobic training consisted of four-weeks of stationary bicycle training, five times per week for 30-minute sessions. Home balance training consisted of performing the same duration of easy, moderate, and/or hard exercises. OUTCOME MEASURES: Scale for the Assessment and Rating of Ataxia (SARA), maximal oxygen consumption (VO2max), Dynamic Gait Index (DGI), Timed up and Go (TUG), gait speed RESULTS: All 20 participants completed assigned training with no major adverse events. Seven of each group attained target training duration, frequency, and intensity. Although both groups had significant improvements in ataxia severity, balance, and gait measures, there were greater improvements in individuals who performed aerobic training in ataxia severity and maximal oxygen consumption when compared to balance training. The effect size for these outcome measures was determined to be large, indicating a phase II trial comparing the benefits of aerobic and balance training was feasible and required 26 subjects per group. Improvements in SARA score and VO(2)max remained in the aerobic training group at 3 months post-training, but these improvements were trending back to baseline. In contrast, all balance group measures for pre-training and 3 month post-training were statistically similar. CONCLUSIONS: A phase II trial comparing balance and aerobic training in individuals with cerebellar degeneration is feasible. Benefits trended back toward baseline after training stopped, although benefits of longer duration exercise programs still need to be determined.

For those with irregular gait, re-calibration of motor control strategies and retraining of coordination are key goals. Thoughtful external forces or resistances during repetitive tasks can reprogram motor control patterns and strategies. Prior work in our lab has utilized this theory to improve gait in various patient groups using the Tethered Pelvic Assist Device (TPAD), a treadmill-based robotic trainer. In this paper, we propose a new, portable extension of the TPAD, which relies on an open-loop, forward kinematics based controller to remove the restriction of walking in the laboratory on a treadmill, and therefore accommodates overground ambulation. To evaluate the effects of this new control scheme and the effects of the users holding the mobile TPAD frame, a dataset of walking in four conditions was collected from eight healthy individuals. When applying a constant pelvic loading force of 10% body weight, the mean ground reaction force increased by 8.2±7.7% when the individual holds the walker frame and 11.1±7.8% when no hand contact is made. The mobile TPAD was shown to still induce a targeted loading on individuals during treadmill walking. The validation of this mobile device’s controller and characterization of holding the frame allow overground studies to be conducted, and now opens the door to new training paradigms for overground gait training.

OBJECTIVE: To elucidate the effect of step-synchronized vibration training using PDShoe on balance, gait, and quality of life in patients of Parkinson’s disease (PD) with freezing of gait (FOG).MATERIALS AND METHODS: In a pilot study, 17 patients of PD with FOG were recruited for step-synchronized vibration training. The training involved 10 sessions of gait training over 2 weeks. Each session included three 6-min bouts of walking with step-synchronized vibration applied to the second metatarsal head and medial surface of calcaneus. Participants were assessed with the Unified Parkinson’s Disease Rating Scale-III (UPDRS III), Timed Up and Go (TUG) test, Berg Balance Scale (BBS), Timed 10-Meter Walk Test, Freezing of Gait Questionnaire (FOG-Q), Falls Efficacy Scale-International (FES-I), and Parkinson’s Disease Questionnaire-39 (PDQ-39). Measurements were collected pre-intervention, post-intervention, and at a 2-week follow-up. Friedman test followed by Wilcoxon signed-rank test were used for statistical analysis.RESULTS: All participants completed the intervention without any adverse effects. Fifteen participants reported for a follow-up evaluation 2 weeks after intervention. There was statistically significant improvement in UPDRS III (P = 0.044) and significant improvement in TUG test (P = 0.005), BBS (P = 0.026), FES-I (P = 0.041), and PDQ-39 (P = 0.021) scores between pre and follow-up evaluations. No significant changes were seen in FOG-Q and Timed 10-Meter Walk Test.CONCLUSION: Step-synchronized vibration is a novel intervention to improve balance, gait, motor features, and quality of life in patients of PD with FOG. Further research is warranted to confirm the results found in this pilot study.

Background Virtual reality (VR) has been used to study locomotor adaptability during balance-demanding tasks by exploring how humans react and adapt to the virtual environment (VE) and discordant sensorimotor stimulations. Previous research primarily focused on treadmill walking and little is known regarding the propensity for gait adaptations during overground walking and over time. Research question To what extent healthy young adults modify and adapt gait during overground walking in a VE and with continuous multidirectional perturbations of the visual field while wearing a VR headset? Methods Twelve healthy young adults walked for 6 min on an instrumented walkway in four different conditions: RE, VE, and VE with antero-posterior (AP) and medio-lateral (ML) pseudo-random oscillations of the visual field. For each condition, stride length (SL), stride width (SW), stride time (ST) and their variability (SLV, SWV, and STV) were calculated using one-minute walking intervals. A 2-way repeated-measures ANOVA was performed to determine the main and interaction effects of the walking conditions and time. Results Participants took shorter SL and showed higher SWV while walking in the VE. Perturbations of the visual field resulted in reduced SL, larger SW, and higher stride variability (i.e., SLV, SWV, and STV). The response was anisotropic, such that effects were more pronounced during the ML compared to AP perturbations. Over time, participants adapted to the VE and the visual perturbations by increasing SL and reducing SW, SLV, STV, and ST (only during VE and ML conditions). SWV did not adapt over time. Significance The paper provided first evidence for visuomotor adaptations during unperturbed overground walking and during visual perturbations while wearing a VR headset. It represents an initial investigation that may help the development of new VR methods for early detection and remediation of gait deficits in more ecological conditions.

This article presents a novel robotic brace for the treatment of scoliosis. The motivation of this new device comes from the shortcomings in current braces including the rigid brace and the soft brace. Besides, the novel active brace can be used not only for applying active corrective forces on spine, but also for the rehabilitation exercise. The design and control architectures are described for the novel brace and genetic algorithm is used to obtain optimal structural parameters. Two Stewart platforms connected in series form this brace which is driven by 12 electric actuators. Each platform can be controlled in motion or force mode independently. The device can move in six orientations in motion mode and apply six-degree-of-freedom forces on the spine in force mode. In order to evaluate the function and performance of the dynamic brace system, a simple proportional–integral–differential control strategy is employed in both the two control modes. Experimental results depict that the proposed device can respond to the desired position/force commands excellently.

Standing postural control requires a complex interaction between the sensory and motor systems. Among sensory inputs, proprioception plays a fundamental role in the fine control of postural movements. In some neuromotor disorders, defects in the proprioceptive system may be associated with unsteady, uncoordinated, and exacerbated upper body movements during activities of daily living that may secondarily result in imbalance, falls, and severe injuries. Passive or active proprioceptive interventions are implemented routinely as a critical part of rehabilitation programs that target postural balance disorders. In this study, we have created a novel multimodal robotic platform merging both passive and active modalities to enhance upper body control. We hypothesize that the combination of passive resistance at pelvis in combination with active control of the lower thorax via assist-as-needed haptic feedback can enhance standing postural control. To test this hypothesis, we recruited ten healthy adults and had them perform dexterous reaching tasks either with or without a robotic system, while they stood unstably on a balance ball. The results of our pilot study show that individuals can improve postural stability of the upper body by selectively reducing upper trunk motion relative to caudal segments in the direction of the reaching arm, after training with the robotic platform.

Exoskeletons for gait training commonly use a rigid-linked "skeleton" which makes them heavy and bulky. Cable-driven exoskeletons eliminate the rigid-linked skeleton, providing a lighter and transparent design. Current cable-driven exoskeletons are aimed only at gait assistance by providing short bursts of forces to the leg during walking. It has not yet been shown if these designs are suitable for gait retraining, where rehabilitative forces need to be continuously applied to the leg in response to errors from a desired movement. The goal of this study is to investigate if a cable-driven leg exoskeleton can retrain the gait of human users. Nine healthy subjects were trained by a cable-driven leg exoskeleton to walk in a new gait pattern with 30% increase in step height from their natural gait. After 40 min of training, the gait of the subjects became significantly closer to the target gait than before the training. In three different post-training sessions, the step height of the subjects increased by 22%, 29%, and 31% on an average. In a fourth post-training session, when the subjects were instructed to ignore the training and walk naturally, the step height remained increased by 11%. These results confirm the potential of cable-driven designs in gait training applications.

Dropped head syndrome is often seen in patients with neurological disorders, such as amyotrophic lateral sclerosis. Static collars are often prescribed to these patients to support their head. These collars support the head in one position but do not allow motion to the head. In this letter, we present a novel active neck brace to address this issue and provide assistance to the patients to improve their neck range of motion. This brace has three degrees-of-freedom and allows improved range of motion to the head and neck. We have developed a joystick interface for this brace to allow the user to carry out their intended head rotation with assistance of the brace. In order to assess the feasibility of the use of this brace, we present a study that recruited eight healthy subjects. We simultaneously recorded the motion of the head, electromyography of the neck muscles, and force/torque applied through the brace to the head. The results show that the brace provides support to the head and subjects activate their muscles less when assisted by the brace using the joystick.

To evaluate the association between Dizziness Handicap Inventory-Screening version (DHI-S) score and spatiotemporal gait parameters using SoleSound, a newly developed, inexpensive, portable footwear-based gait analysis system.Cross-sectional.One hundred eighteen patients recruited from otology clinic.Subjects completed the DHI-S survey and four uninterrupted walking laps wearing SoleSound instrumented footwear on a hard, flat surface for 100 m.For each subject, mean and coefficient of variation (CV) of stride length, cadence, walking speed, foot-ground clearance, double-support time, swing period, and stance-to-swing were computed by considering 40 strides of steady-state walking within each lap. Linear regression models were employed to study correlations between these variables and DHI-S scores after adjusting for age, sex, and race/ethnicity.Patients with higher DHI-S score took shorter steps and less steps per minute (-0.017 m and -1.1 steps/min per every four-point increase in DHI-S score, p 0.05) than patients with a lower DHI-S score, with slower walking speed (-0.025 m/s per every four-point increase in DHI-S score, p 0.01). Additionally, patients with higher DHI-S scores showed larger variability in all analyzed temporal parameters (+0.1% for CV of cadence, +0.5% for CV of double support period, +0.2% for CV of swing period, and +0.4% for CV of stance-to-swing, per every four-point increase in DHI-S score, p 0.01).SoleSound was effective in measuring a wide range of gait parameters. Patients' self-perception of vestibular handicap, as assessed with DHI-S, is associated with deterioration in measurable gait parameters independent of age.

Gait and balance disorders are major problems that contribute to falls among subjects with Parkinson’s disease (PD). Strengthening the compensatory responses through the use of balance perturbations may improve balance in PD. To date, it is unclear how PD affects the ability to react and adapt to perturbations delivered while walking. This study aims to investigate how PD affects the ability to walk, respond to balance perturbations, and produce acute short-term effects to improve compensatory reactions and gait stability. A cable-driven robot was used to train nine patients with PD and nine age-matched controls with multidirectional waist-pull perturbations while walking on a treadmill. Margin of stability and base of support were evaluated while walking without cables and reacting to the perturbations. PD was associated with a reduced stability in the forward direction and the inability to produce proactive anticipatory adjustments. Both groups were able to improve the response to the disturbances and produce short-term aftereffects of increased gait stability once the cables were removed. A single session of perturbation-based balance training produced acute effects that ameliorated gait instability in PD. This result is encouraging for designing new therapeutic interventions that remediate falls risk.

Improving functional motor deficits in patients with neurological and musculoskeletal disorders has been a primary objective of rehabilitation. Task-oriented training in physical environments is a leading approach for rehab training utilizing tasks that are challenging, adaptable, and meaningful. Although different training paradigms can be utilized in a laboratory setting, they often require expensive training equipment and personnel, limiting the number of training sessions. Creating an effective virtual reality (VR) training environment can greatly increase the repetition, cognitive engagement, and training variability. Specifically, dynamic trunk control is required for the successful completion of everyday tasks. These tasks require coordination between the head, upper and lower trunk, and the pelvis. We have developed a novel robotic device, trunk support trainer (TruST) and a VR gaming environment, which allows training in a seated posture at and beyond an individual's point of stability failure using an assist-as-needed force tunnel strategy. The VR environment consists of challenging reaching tasks where the subject's dominant hand is used to manipulate a VR drone. We conducted a study that involved three groups: ten adult subjects trained using VR, ten adult subjects trained in a physical environment (PR), and ten without TruST assistance (control group) to investigate the changes in trunk kinematics. Our study supports the hypothesis that a single training session with TruST in both VR and PR can increase lower trunk range of motion. This approach may be useful for creating training variability and translating therapy in home settings.

Head drop is a symptom commonly seen in patients with amyotrophic lateral sclerosis. These patients usually experience neck pain and have difficulty in swallowing and breathing. Static neck braces are used in current treatment. These braces, however, immobilize the head in a single configuration, which causes muscle atrophy. This letter presents the design of a dynamic neck brace for the first time in the literature, which can both measure and potentially assist in the head motion of the human user. This letter introduces the brace design method and validates its capability to perform measurements. The brace is designed based on kinematics data collected from a healthy individual via a motion capture system. A pilot study was conducted to evaluate the wearability of the brace and the accuracy of measurements with the brace. This study recruited ten participants who performed a series of head motions. The results of this human study indicate that the brace is wearable by individuals who vary in size, the brace allows nearly $70\%$ of the overall range of head rotations, and the sensors on the brace give accurate motion of the head with an error of under $5^{\circ }$ when compared to a motion capture system. We believe that this neck brace can be a valid and accurate measurement tool for human head motion. This brace will be a big improvement in the available technologies to measure head motion as these are currently done in the clinic using hand-held protractors in two orthogonal planes.

Dynamic seated trunk control is required during the execution of many everyday tasks. These tasks require an intricate coordination between the head, upper and lower trunk, and the pelvis. Furthermore, reaching beyond the arm's length requires precise joint control and intersegmental coordination. With practice specificity, humans can learn particular motor skills that may be performed across contexts of similar characteristics. As new tasks are explored, human movements are learned and organized by the release and constraint of degrees-of-freedom, and the modulation of joint amplitudes that are specific to the task demands. Thus, by providing seated reach training without foot support that challenges postural control close to and beyond the stability limits or point of stability failure, an individual with an optimal level of trunk assistance could improve postural control by increasing the range of motion of the trunk and expand the boundaries that define the point of stability failure. We have developed a novel cable robotic device, trunk support trainer (TruST), which allows training of seated posture at and beyond an individual's point of stability failure during volitional trunk displacement. This is accomplished by creating a force tunnel to support posture beyond the sitting stability region. The system provides an assist-as-needed force strategy to support the trunk. We conducted a proof-of-concept study with 20 healthy adult subjects (10 experimental and 10 control) to investigate the changes in lower trunk center of mass (COM) displacement and trunk kinematics. Our study supports the hypothesis that a single training session with TruST at and beyond the point of stability failure increases lower trunk COM displacement and increases the lower trunk and pelvic rotation. The findings suggest that this approach may be useful for training patients with neurological and musculoskeletal disorders where children or adults have compromised postural stability.

Objectives: To investigate whether people with cerebellar degeneration can perform rigorous aerobic exercise and to assess the clinical impact of training. Design: Randomized single-blinded controlled, feasibility study comparing aerobic training to no training. Setting: Home intervention, assessments conducted at an academic medical center. Subjects: Twenty individuals with cerebellar degeneration caused by a range of genetic disorders. Intervention: Aerobic training consisted of four weeks of stationary bicycle training, five times per week for 30-minute sessions. Intensity ranged from 65% to 80% of the participant’s maximal heart rate determined during cardiopulmonary exercise testing. Main measures: Primary outcome measure was change in the Scale for the Assessment and Rating of Ataxia scores. Recruitment rate, adherence, drop-out, and adverse events were also determined. The treatment was considered technically feasible if participants achieved target training frequency, duration, and intensity. Results: The 20 participants mean age was 50 years (standard deviation 15.65 years) and average Scale for the Assessment and Rating of Ataxia score was 9.6 (standard deviation 3.13). Ten participants were randomized to aerobic training and 10 to no training. Seven participants in the aerobic group attained target training duration, frequency, and intensity. There was a mean reduction in ataxia severity of 2.1 points (standard deviation 1.26) with four weeks of aerobic training, whereas ataxia severity increased by 0.3 (standard deviation 0.62) in the control group over the same period. Walking speed, balance measures, and fitness also improved in individuals who performed aerobic exercise. Conclusions: Rigorous aerobic training is feasible in people with cerebellar degeneration. Improvements in ataxia, balance, and gait are promising.

Older adults have difficulty adapting to new visual information, posing a challenge to maintain balance during walking. Virtual reality can be used to study gait adaptability in response to discordant sensorimotor stimulations. This study aimed to investigate age-related modifications and propensity for visuomotor adaptations due to continuous visual perturbations during overground walking in a virtual reality headset. Twenty old and twelve young subjects walked on an instrumented walkway in real and virtual environments while reacting to antero-posterior and medio-lateral oscillations of the visual field. Mean and variability of spatiotemporal gait parameters were calculated during the first and fifth minutes of walking. A 3-way mixed-design ANOVA was performed to determine the main and interaction effects of group, condition and time. Both groups modified gait similarly, but older adults walked with shorter and slower strides and did not reduce stride velocity or increase stride width variability during medio-lateral perturbations. This may be related to a more conservative and anticipatory strategy as well as a reduced perception of the optic flow. Over time, participants adapted similarly to the perturbations but only younger participants reduced their stride velocity variability. Results provide novel evidence of age- and context-dependent visuomotor adaptations in response to visual perturbations during overground walking and may help to establish new methods for early identification and remediation of gait deficits.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To measure and expand the sitting workspace of participants with spinal cord injury (SCI) with the Trunk-Support-Trainer (TruST). SETTING: Columbia University. METHODS: TruST is a motorized-cable belt placed around the torso. Participants performed maximal trunk excursions along eight directions, radiating in a star-shape, to define their seated postural limits and workspace area (cm(2)). TruST was configured to apply “assist-as-needed” forces when the trunk moved beyond these postural limits. Kinematics were collected to examine trunk control. The clinical features of the sample (n = 5) were documented by neurological injury, dynamometry, the American Spinal Injury Association Impairment Scale, and Spinal Cord Independence Measure-III. RESULTS: Statistical significance was examined with paired t-tests. TruST successfully recreated the postural limits of participants and expanded their active sitting workspace (Mean: 123.3 ± SE: 42.8 cm(2), p

This study investigated if training in a virtual reality (VR) environment that provides visual and audio biofeedback on foot placement can induce changes to spatial and temporal parameters of gait during overground walking. Eighteen healthy young adults walked for 23 min back and forth on an instrumented walkway in three different conditions: (i) real environment (RE), (ii) virtual environment (VE) with no biofeedback, and (iii) VE with biofeedback. Visual and audio biofeedback while stepping on virtual footprint targets appearing along a straight path encouraged participants to walk with an asymmetrical step length (SL). A repeated-measures, one-way ANOVA, followed by a pairwise comparison post-hoc analysis with Bonferroni's correction, was performed to compare the step length difference (SLD), stance phase percentage difference (SPPD), and double-support percentage difference (DSPD) between early and late phases of all walking conditions. The results demonstrate the efficacy of the VE biofeedback system for training asymmetrical gait patterns. Participants temporarily adapted an asymmetrical gait pattern immediately post-training in the VE. Induced asymmetries persisted significantly while later walking in the RE. Asymmetry was significant in the spatial parameters of gait (SLD) but not in the temporal parameters (SPPD and DSPD). This paper demonstrates a method to induce unilateral changes in spatial parameters of gait using a novel VR tool. This study provides a proof-of-concept validation that VR biofeedback training can be conducted directly overground and could potentially provide a new method for treatment of hemiplegic gait or asymmetrical walking.

Functional rehabilitation of patients with spinal cord injury remains a current challenge. Training these patients to successfully stand is the first step towards restoring advanced skills such as walking. To address this need, we have developed a novel robotic stand trainer that can apply controlled forces on the trunk and the pelvis of a user, while controlling the knee angle. The stand trainer utilizes cables to apply assistive, resistive, or perturbation forces at the trunk, pelvis, and the knees, simultaneously. We have conducted a human study to validate the system. In this study, we applied multi-direction perturbation forces either at the pelvis or the trunk while assist-as-needed forces were applied to the other segment to keep balance. This study characterizes the human kinematics and measures of balance under the perturbations and assistive forces on the human body. Results shows that the level of force-field assistance (trunk or pelvis) directly affects the motion of the trunk, pelvis, and center of pressure. This provides a quantitative framework to restore balance in patients while providing assistance only when needed. This stand trainer can potentially free up therapists to attend to higher level rehabilitation goals and objectively assist patients to engage in interventions that challenge both their musculoskeletal and sensorimotor impairments.

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

Background: Gait impairment is common in spinal muscular atrophy (SMA) and is described using clinical assessments and instrumented walkways. Continuous over-ground walking has not been studied. Methods: Nine SMA participants completed the six-minute walk test (6MWT) and 10-meter walk/run wearing instrumented footwear (SoleSound). Data were simultaneously collected using a reference system (GAITRiteTM). The root mean square error (RMSE) indicated criterion validity. The decrease in walking speed represented fatigue. Foot loading patterns were evaluated using force sensors. Results: The RMSE for stride time, length, and velocity ranged from 1.3–1.7%. Fatigue was 11.6±9.1%, which corresponded to an average deceleration of 0.37±0.28mm/s2. Participants spent most of stance without heel contact. Forefoot contact occurred early in the gait cycle. Conclusions: These results suggest that footwear-based devices are an alternative to specialized equipment for gait assessment. Better understanding of gait disturbances should inform ongoing treatment efforts and provide a more sensitive outcome measure. This article is protected by copyright. All rights reserved.

Quantitative gait analysis enables clinicians to evaluate patient mobility and to diagnose neuromuscular disorders. The clinical application of gait analysis is currently limited by the high operating costs of gait laboratories. The use of instrumented footwear that performs out of the lab measurements on subjects' walking patterns is a promising way to overcome this limitation. Besides serving as assessment tools, such devices can also act as retraining tools that help regulate a patient's gait with acoustic or vibrotactile stimuli.

Mobility is a causal factor in infant development. Neural impaired infants, e.g., with cerebral palsy (CP), are at risk for further developmental delays due to lack of self-generated mobility. It is possible that these infants may benefit from robot-enhanced mobility, where the mobility comes from a robot that the child drives via a joystick. We believe that such a mobility experience will enrich the child and minimize further delays in attaining some of the childhood developmental and social milestones. In order to address the broad goal posed earlier, one can ask the following simpler questions: 1) Will children with CP learn to drive a robot using a joystick? 2) Will these children with CP sustain interest in doing so over multiple training sessions? 3) Will such a robot-enhanced mobility impact development scores in this group of children? 4) Will a larger number of robotic training sessions be more effective to enhance these developmental scores ? This paper reports the first results from two pilot studies conducted by our research group on robot-assisted mobility training, where children with CP performed two tasks across multiple training sessions. We found that, after training with the robot, children who performed 30 training sessions, labeled as “long-term study,” advanced in their driving skills and showed significant improvements in clinical scores such as Gross Motor Function Measure, Quality of Upper Extremity Skills Test, and Pediatric Evaluation of Disability Inventory (mobility with/without caregiver and social function with/without caregiver).

Introduction: Postoperative neck and shoulder dysfunction is recognized as a morbidity of neck dissection (ND) in head and neck cancer patients. However, the precise biomechanics and duration of neck mobility limitation have not been fully described. In current practices of more selective NDs, studies employing precise measurement techniques are needed to quantify the risk of postoperative neck range of motion (ROM) impairment in this patient population. Study Design: A prospective pilot study of five patients undergoing selective ND for head and neck cancer was conducted. A novel measurement brace was used to collect kinematic and concurrent EMG data on active ROM during standardized tasks for prespecified neck muscle groups at baseline and following ND. Methods: Patients without prior surgery or radiation undergoing unilateral ND for head and neck cancer were included. Patients were evaluated preoperatively and four weeks postoperatively. A novel neck brace developed for the purposes of this study was utilized to measure flexion, extension, lateral bending, axial rotation, and rolling movements. Angle of motion was measured from the neutral position to the end of each movement type as well as during total ROM from one movement type to the other (i.e., from neutral position to flexion as well as from flexion to extension). Baseline and postoperative EMG onset/offset data were collected for bilateral SCM, splenius capitis, and trapezius muscles to correlate muscle activation with angle of motion. Results: Five patients undergoing unilateral modified ND for cutaneous, oral cavity, or oropharyngeal squamous cell carcinoma completed preoperative and postoperative assessments. The average age was 57 years (54-60; sd 2.6). The greatest change in total ROM following surgery was seen in lateral bending, with a mean angle change of 17.3 (6.9-30.6; sd 8.5). Differences in lateral bending from neutral position were also seen for both the dissected and nondissected sides. Although degree of flexion and extension ROM were not affected by surgery overall, changes in the pattern of muscle group activation were evident. Conclusions: Measurement brace recordings suggest that active ROM limitation is most pronounced with lateral neck bending both to the ipsilateral and contralateral side of ND compared to other neck movements. EMG correlate data show increased variability in activation of muscle groups with flexion and extension movements. These preliminary results suggest that this device may serve as a useful diagnostic tool for patients undergoing ND. Additional data are needed to determine statistical and clinical significance of changes measured using this device. Future results may help guide clinicians in counseling patients about expectations following surgery as well as lead us to potential therapeutic targets from changes in muscle activation. Citation Format: Biing-Chwen Chang, Haohan Zhang, Ade Obayemi, Sallie Long, Scott Troob, Sunil Agrawal. A novel measurement neck brace for detecting range-of-motion changes with electromyography correlates in head and neck cancer patients undergoing neck dissection: A prospective pilot study [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B22.

Stair climbing is an intense physical activity and requires large range of motion at the joints, adequate muscle strength, and balance control. A powered stairmill, integrated with a gait rehabilitation device, can potentially be used for training those who have difficulty climbing stairs. In order to assess the effectiveness of such an approach, it is necessary to understand the similarities and differences in walking on regular stairs and on a stairmill. We have conducted an experiment to compare the differences in kinematics and muscle activations during climbing on regular stairs and a stairmill. Twelve subjects participated in this study. They first walked on regular stairs five times and then performed a one-minute continuous walking on a stairmill. The results showed several important differences. During continuous walking on a stairmill, when compared to regular stairs, there was (i) an increase in the percentage of stance phase during a walking cycle, (ii) a higher angle of plantarflexion of the ankle during the transition from stance phase to swing phase, and (iii) a decrease in muscle activation of the tibialis anterior during swing phase. These differences would provide additional insights into the design of future rehabilitation systems and to interpret human data obtained from stairmills.

Gait disorders are major problems among patients with cerebellar ataxia (CA) and Parkinson’s disease (PD). Little is known on how damages to the cerebellum or the basal ganglia affect the recovery responses to external gait perturbations. Six patients with CA, six patients with PD and six healthy controls (HC) were exposed to 9 blocks of 8 antero-posterior (AP) and medio-lateral (ML) perturbations. AP and ML Base of support (BoS) were compared between groups at perturbation onset and the following five heel strikes. HCs showed longer AP BoS than the CA and PD groups. Patients with CA showed a wider ML BoS than the HC and PD groups. Patients with PD were unable to take longer or larger steps when necessary (i.e., in reaction to anterior and medial perturbations). These findings could help to design specific perturbation-based training in patients with different degenerative neurological diseases.