Levels Of Body Weight Support Research Articles

Effects of body weight support training on balance and walking function in stroke patients: a systematic review and meta-analysis.

To comprehensively and quantitatively evaluate the impact of body weight support training (BWST) on balance and gait function in stroke patients based on an evidence-based basis and to identify the most effective intervention strategies. PubMed, Web of Science, The Cochrane Library, CNKI, Wanfang, and Chinese SinoMed Database were searched until November 25, 2023. Quality assessment and meta-analysis were performed using RevMan 5.2 and Stata 14.0 software. A total of 31 randomized controlled trials involving 1,918 patients were included in the study. The meta-analysis demonstrated that body weight support training (BWST) significantly improved Berg Balance Scale (BBS) scores (MD = 3.60; 95% CI: 1.23 to 5.98; p = 0.003), gait speed (SMD = 0.77; 95% CI: 0.38 to 1.15; p < 0.0001), and step length (SMD = 0.46; 95% CI: 0.19 to 0.72; p = 0.0008) in stroke patients compared to conventional rehabilitation. For enhancing balance function, the most effective interventions were identified as a disease duration of 3-6 months (MD = 5.16; 95% CI: 0.76 to 9.57; p = 0.02), intervention time of 4-8 weeks (MD = 5.70; 95% CI: 2.90 to 8.50; p < 0.0001), a maximum body weight support level above 30% (MD = 3.80; 95% CI: 1.48 to 6.13; p = 0.001), and a maximum training walking speed of 0.2 m/s or more (MD = 4.66; 95% CI: 0.37 to 9.70; p = 0.03). For improving walking function, the optimal interventions were also a disease duration of 3-6 months (gait speed: SMD = 0.59; 95% CI: 0.15 to 1.03; p = 0.008; step length: SMD = 0.27; 95% CI: 0.06 to 0.56; p = 0.04), intervention time of 4-8 weeks (gait speed: SMD = 1.01; 95% CI: 0.44 to 1.59; p = 0.0006; step length: SMD = 0.83; 95% CI: 0.54 to 1.12; p < 0.00001), a maximum body weight support level above 30% (gait speed: SMD = 0.79; 95% CI: 0.36 to 1.22; p = 0.0003; step length: SMD = 0.79; 95% CI: 0.47 to 1.11; p < 0.00001), and a maximum training walking speed of 0.2 m/s or more (gait speed: SMD = 1.26; 95% CI: 0.62 to 1.90; p = 0.0001; step length: SMD = 0.85; 95% CI: 0.38 to 1.31; p = 0.0003). Compared with conventional rehabilitation training, BWST demonstrates superior efficacy in enhancing balance and walking function in stroke patients, with a consistent optimal intervention strategy. The most effective program includes a disease duration of 3-6 months, an intervention period of 4-8 weeks, a maximum body weight support of 30% or more, and a maximum training walking speed of 0.2 m/s or greater. http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022358963.

Characterizing Bodyweight-Supported Treadmill Walking on Land and Underwater Using Foot-Worn Inertial Measurement Units and Machine Learning for Gait Event Detection.

Gait rehabilitation commonly relies on bodyweight unloading mechanisms, such as overhead mechanical support and underwater buoyancy. Lightweight and wireless inertial measurement unit (IMU) sensors provide a cost-effective tool for quantifying body segment motions without the need for video recordings or ground reaction force measures. Identifying the instant when the foot contacts and leaves the ground from IMU data can be challenging, often requiring scrupulous parameter selection and researcher supervision. We aimed to assess the use of machine learning methods for gait event detection based on features from foot segment rotational velocity using foot-worn IMU sensors during bodyweight-supported treadmill walking on land and underwater. Twelve healthy subjects completed on-land treadmill walking with overhead mechanical bodyweight support, and three subjects completed underwater treadmill walking. We placed IMU sensors on the foot and recorded motion capture and ground reaction force data on land and recorded IMU sensor data from wireless foot pressure insoles underwater. To detect gait events based on IMU data features, we used random forest machine learning classification. We achieved high gait event detection accuracy (95-96%) during on-land bodyweight-supported treadmill walking across a range of gait speeds and bodyweight support levels. Due to biomechanical changes during underwater treadmill walking compared to on land, accurate underwater gait event detection required specific underwater training data. Using single-axis IMU data and machine learning classification, we were able to effectively identify gait events during bodyweight-supported treadmill walking on land and underwater. Robust and automated gait event detection methods can enable advances in gait rehabilitation.

Variation of body weight supported treadmill training parameters during a single session can modulate muscle activity patterns in post-stroke gait

Evidence supporting the benefits of locomotor training (LT) to improve walking ability following stroke are inconclusive and could likely be improved with a better understanding of the effects of individual parameters i.e., body weight support (BWS), speed, and therapist assistance and their interactions with walking ability and specific impairments. We evaluated changes in muscle activity of thirty-seven individuals with chronic stroke (> 6 months), in response to a single session of LT at their self-selected or fastest-comfortable speed (FS) with three levels of BWS (0%, 15%, and 30%), and at FS with 30% BWS and seven different combinations of therapist assistance at the paretic foot, non-paretic foot, and trunk. Altered Muscle Activation Pattern (AMAP), a previously developed tool in our lab was used to evaluate the effects of LT parameter variation on eight lower-extremity muscle patterns in individuals with stroke. Repeated-measures mixed-model ANOVA was used to determine the effects of speed, BWS, and their interaction on AMAP scores. The Wilcoxon-signed rank test was used to determine the effects of therapist-assisted conditions on AMAP scores. Increased BWS mostly improved lower-extremity muscle activity patterns, but increased speed resulted in worse plantar flexor activity. Abnormal early plantar flexor activity during stance decreased with assistance at trunk and both feet, exaggerated plantar flexor activity during late swing decreased with assistance to the non-paretic foot or trunk, and diminished gluteus medius activity during stance increased with assistance to paretic foot and/or trunk. Therefore, different sets of training parameters have different immediate effects on activation patterns of each muscle and gait subphases.

Body Weight Control Is a Key Element of Motor Control for Toddlers' Walking.

New-borns can step when supported for about 70-80% of their own body weight. Gravity-related sensorimotor information might be an important factor in developing the ability to walk independently. We explored how body weight support alters motor control in toddlers during the first independent steps and in toddlers with about half a year of walking experience. Sixteen different typically developing children were assessed during (un)supported walking on a running treadmill. Electromyography of 18-24 bilateral leg and back muscles and vertical ground reaction forces were recorded. Strides were grouped into four levels of body weight support ranging from no (<10%), low (10-35%), medium (35-55%), and high (55-95%) support. We constructed muscle synergies and muscle networks and assessed differences between levels of support and between groups. In both groups, muscle activities could be described by four synergies. As expected, the mean activity decreased with body weight support around foot strikes. The younger first-steps group showed changes in the temporal pattern of the synergies when supported for more than 35% of their body weight. In this group, the muscle network was dense with several interlimb connections. Apparently, the ability to process gravity-related information is not fully developed at the onset of independent walking causing motor control to be fairly disperse. Synergy-specific sensitivity for unloading implies distinct neural mechanisms underlying (the emergence of) these synergies.

Impact of Varying Exercise Intensity on Oxygen Uptake and Cardiovascular Response during Body Weight Supported Treadmill Walking in Healthy Adults

Body Weight Supported Treadmill Training (BWSTT) is effectively used in locomotive training for patients with neurologic and musculoskeletal deficits. The impact of BWSTT on oxygen uptake (VO₂) and cardiovascular (HR and BP) response in patients has been shown to be variable, possibly due to level of Body Weight Support (BWS) or exercise intensity.

Role of Antigravity Training in Rehabilitation and Return to Sport After Running Injuries

AbstractAnti-gravity treadmill training is a therapeutic option to help recovering runners return to activity after injury. This current concept paper provides a synopsis of the latest evidence of the biomechanical and metabolic changes that occur with body weight support (BWS) treadmill training, effects of antigravity treadmill training on clinical outcomes and clinical case studies in injured runners. Literature searches identified studies with descriptive, experimental and interventional designs and case studies that examined acute and chronic use of antigravity treadmills in runners and relevant populations. Laboratory-based studies were included to provide technical considerations for rehabilitation programming. Antigravity treadmills use causes reductions in cadence, ground reaction forces (GRF), GRF impulses, knee and ankle range of motion, and vertical stiffness, with elevations in stride duration, flight time, ground contact time, and plantarflexion. Antigravity treadmills appear useful across a spectrum of injuries in runners, including postsurgical repair of osteochondral defect, stress reactions (medial tibia, pelvis), and lumbar disc herniation. Runners may preserve aerobic fitness, muscle activation patterns, and muscle mass during recovery compared to traditional rehabilitation protocols. Technical considerations for accurate loading include treadmill frame adjustment to appropriate height to ensure accuracy of level of BWS while running, and monitoring for fast cadence to ensure impact loading rates remain low. Speed or grade can be increased to maintain metabolic demand and fitness while minimizing bone and tissue loading. Monitoring for symptom provocation will guide protocol adjustments to BWS and prescriptions. Once able to run pain-free (sustained or interval) >95% BWS for >30 min, the runner is likely ready to safely transition to ground running. Antigravity treadmill training can be considered when available to facilitate smooth transition back to ground running in a conditioned state.

Influence Of Running Direction On Metabolic Costs May Be Attenuated By Body Weight Support

During running on land, backward running produces greater metabolic and muscular demands than when running forward at the same speed. This type of research is important to identify the similarities and differences of forward and backward running, in order to best prescribe backward running as a cross-training stimulus for forward running. PURPOSE: The purpose of this study was to investigate the influence of running direction on metabolic, biomechanical, and perceptual demands during running at different levels of body weight support (BWS). METHODS: Thirteen participants ran forward and backward on a lower body positive pressure treadmill at 0%BWS, 20%BWS, and 50%BWS conditions at the same speed. We measured oxygen uptake (VO2), heart rate (HR), muscle activity (rectus femoris, biceps femoris, tibialis anterior, gastrocnemius), and stride frequency during the tests. Additionally, we calculated metabolic cost of transport (CoT). Furthermore, we used rating of perceived exertion (RPE) and feeling scale to investigate participants’ perceptual demands during the tests. VO2, HR, CoT, RPE, feeling scale, muscle activity, and stride frequency were analyzed using a 2 (directions) x 3 (BWS) repeated measures analysis of variance (α = 0.05). RESULTS: VO2, HR, and CoT were influenced by the interaction of BWS and running direction (P < 0.01). For example, CoT during backward running were greater than when running forward only when running at 0%BWS (4.5 ± 1.1 and 5.8 ± 1.4 J/kg/m in CoT for forward and backward running, respectively: P < 0.001). However, muscle activity from the rectus femoris, stride frequency, and RPE during backward running were averages of 113.5%, 11.3%, and 2.8 rankings greater than when running forward, respectively, regardless of BWS (P < 0.001). CONCLUSIONS: Backward running may require greater biomechanical and perceptual demands compared to forward running at the same speed, regardless of BWS. However, the influence of a change in running direction on metabolic demands may be attenuated by BWS. Supported by JSPS Grant Number 16 K01663.

Control and Evaluation of Body Weight Support Walker for Overground Gait Training

Gait rehabilitation training under robot-assisted partial Body Weight Support (BWS) is a promising technique that helps patients who suffer from a traumatic or congenital brain injury like stroke or cerebral palsy to become independent in daily life activities. In recent years, robotic BWS systems have been widely studied, where the BWS is provided by the robot while the user walks on devices fixed to the environment such as treadmills, thereby gaining functional benefits such as improved gait symmetry and increased walking speed. On the other hand, mobile BWS robots that allow conventional overground walking with well-designed control strategies have been less researched, limiting the widespread adoption of robotic rehabilitation because of the cost effectiveness of fixed robotic devices and poor portability. To address this problem, in our previous study, we developed a mobile BWS walker that allows for overground walking under variable levels of BWS. In this letter, we introduce a system architecture that integrates the walker with a pair of instrumented shoes and discuss different system control strategies including static and variable BWS control. When walking under Static-BWS (SBWS), the subject walks while a constant portion of his/her weight is supported, which might cause an unnatural gait. Using a Variable-BWS (VBWS), the provided BWS can be adjusted according to human's gait events to provide a more natural gait. This letter describes the system architecture, as well as experiments with able subjects that demonstrate the effectiveness of both the SBWS and VBWS control algorithms in relieving part of the subjects’ body weight. Specifically, by synchronizing the controlled BWS with human gait events, users were able to walk more naturally, particularly under a high level of BWS.

Metabolic and Cardiovascular Effects of Body Weight Support Treadmill Walking in Healthy Adults

Purpose: Limited and conflicting evidence exists regarding the metabolic and cardiovascular responses of body weight support (BWS) treadmill training (BWSTT). The purpose of this study was to describe the metabolic (as assessed by oxygen uptake) and cardiovascular responses to varying levels of BWSTT in healthy adult subjects. Methods: Twenty-one subjects (10 females; 34.5 [6.7] yr.; 74.6 [14.3] kg; 170.8 [6.9] cm; 26.1 [5.3] kg/m2) provided their informed consent to participate in 3 5-minute walking trials at a self-selected treadmill speed, with BWS of 0%, 15%, and 30%. Test order was randomized. Subjects rested at least 5 minutes between trials and did not begin another trial until the heart rate (HR) was &lt;5 bpm of HR rest. Mean HR, blood pressure (BP), oxygen uptake, and rating of perceived exertion (RPE) were determined from the last 3 minutes of each trial. Mean values for all variables were assessed for difference between trials using repeated-measures analysis of variance. Results: At rest, HR was 78.2 (11.5) bpm and BP was 121.2 (7.9)/76.9 (8.0) mm Hg. Mean walking speed of subjects was 65.4 m/min. Heart rate and systolic BP significantly (P &lt; .05) increased from rest with exercise at each level of BWS, with no significant difference in diastolic BP seen from rest to exercise at all BWS levels. There was no statistical difference among levels of BWS for HR, BP, RPE, oxygen uptake, respiratory exchange ratio, respiratory rate, tidal volume, and metabolic equivalent of tasks. Conclusions: Healthy adult subjects walking at self-selected speeds at BWS levels up to 30% fail to demonstrate significant changes in metabolic and cardiovascular responses.

Effect of motor-assisted elliptical training speed and body weight support on center of pressure movement variability

BackgroundA motor-assisted elliptical trainer is being used clinically to help individuals with physical disabilities regain and/or retain walking ability and cardiorespiratory fitness. Unknown is how the device’s training parameters can be used to optimize movement variability and regularity. This study examined the effect of motor-assisted elliptical training speed as well as body weight support (BWS) on center of pressure (CoP) movement variability and regularity during training. MethodsCoP was recorded using in-shoe pressure insoles as participants motor-assisted elliptical trained at three speeds (20, 40 and 60 cycles per minute) each performed at four BWS levels (0 %, 20 %, 40 %, and 60 %). Separate two-way repeated measures ANOVAs (3 × 4) evaluated impact of training speed and BWS on linear variability (standard deviation) and non-linear regularity (sample entropy) of CoP excursion (anterior-posterior, medial-lateral) for 10 dominant limb strides. FindingsTraining speed and BWS did not significantly affect the linear variability of CoP in the anterior-posterior or medial-lateral directions. However, sample entropy in both directions revealed the main effect of training speed (p < 0.0001), and a main effect of BWS was observed in the medial-lateral direction (p = 0.004). Faster training speeds and greater levels of BWS resulted in more irregular CoP patterns. InterpretationThe finding that speed and BWS can be used to manipulate CoP movement variability when using a motor-assisted elliptical has significant clinical implications for promoting/restoring walking capacity. Further research is required to determine the impact of motor-assisted elliptical speed and BWS manipulations on functional recovery of walking in individuals who have experienced a neurologic injury or illness.

Effects of bodyweight support and guidance force on muscle activation during Locomat walking in people with stroke: a cross-sectional study

BackgroundLocomat is a robotic exoskeleton providing guidance force and bodyweight support to facilitate intensive walking training for people with stroke. Although the Locomat has been reported to be effective in improving walking performance, the effects of training parameters on the neuromuscular control remain unclear. This study aimed to compare the muscle activities between Locomat walking and treadmill walking at a normal speed, as well as to investigate the effects of varying bodyweight support and guidance force on muscle activation patterns during Locomat walking in people with stroke.MethodsA cross-sectional study design was employed. Participants first performed an unrestrained walking on a treadmill and then walked in the Locomat with different levels of bodyweight support (30% or 50%) and guidance force (40% or 70%) at the same speed (1.2 m/s). Surface electromyography (sEMG) of seven muscles of the affected leg was recorded. The sEMG envelope was time-normalised and averaged over gait cycles. Mean sEMG amplitude was then calculated by normalising the sEMG amplitude with respect to the peak amplitude during treadmill walking for statistical analysis. A series of Non-parametric test and post hoc analysis were performed with a significance level of 0.05.ResultsFourteen participants with stroke were recruited at the Yangzhi Affiliated Rehabilitation Hospital of Tongji University (female n = 1; mean age 46.1 ± 11.1 years). Only the mean sEMG amplitude of vastus medialis oblique during Locomat walking (50% bodyweight support and 70% guidance force) was significantly lower than that during treadmill walking. Reducing both bodyweight and guidance increased muscle activity of gluteus medius and tibialis anterior. Activity of vastus medialis oblique muscle increased as bodyweight support reduced, while that of rectus femoris increased as guidance force decreased.ConclusionsThe effects of Locomat on reducing muscle activity in people with stroke were minimized when walking at a normal speed. Reducing bodyweight support and guidance force increased the activity of specific muscles during Locomat walking. Effects of bodyweight support, guidance force and speed should be taken into account when developing individualized Locomat training protocols for clients with stroke.

Robotic body weight support enables safe stair negotiation in compliance with basic locomotor principles

BackgroundAfter a neurological injury, mobility focused rehabilitation programs intensively train walking on treadmills or overground. However, after discharge, quite a few patients are not able to independently negotiate stairs, a real-world task with high physical and psychological demands and a high injury risk. To decrease fall risk and improve patients’ capacity to navigate typical environments, early stair negotiation training can help restore competence and confidence in safe stair negotiation. One way to enable early training in a safe and permissive environment is to unload the patient with a body weight support system. We here investigated if unloaded stair negotiation complies with basic locomotor principles, in terms of enabling performance of a physiological movement pattern with minimal compensation.MethodsSeventeen able-bodied participants were unloaded with 0–50% bodyweight during self-paced ascent and descent of a 4-tread staircase. Spatio-temporal parameters, joint ranges of motion, ground reaction forces and myoelectric activity in the main lower limb muscles of participants were compared between unloading levels. Likelihood ratio tests of separated linear mixed models of the investigated outcomes assessed if unloading affects the parameters in general. Subsequent post-hoc testing revealed which levels of unloading differed from unsupported stair negotiation.ResultsUnloading affected walking velocity, joint ranges of motion, vertical ground reaction force parameters and myoelectric activity in all investigated muscles for stair ascent and descent while step width and single support duration were only affected during ascent. A reduction with increasing levels of body weight support was seen in walking velocity (0.07–0.12 m/s), ranges of motion of the knee and hip (2–10°), vertical ground reaction force peaks (10–70%) and myoelectric activity (17–70%). An increase with unloading was only seen during ascent for ankle range of motion and tibialis anterior activity at substantial unloading.ConclusionsBody weight support facilitates stair negotiation by providing safety and support against gravity. Although unloading effects are present in most parameters, up to 30% body weight support these changes are small, and no dysfunctional patterns are introduced. Body weight support therefore fulfills all the necessary requirements for early stair negotiation training.

Metabolic Costs During Backward Running with Body Weight Support.

We investigated metabolic costs, rating of perceived exertion (RPE), stride frequency (SF), and preferred speed (PS) during forward and backward running at different levels of body weight support (BWS). Participants completed forward and backward running on a lower body positive pressure treadmill at their preferred speed for forward and backward running at 0%BWS, 20%BWS, and 50%BWS. Oxygen uptake (V̇O2), heart rate (HR), RPE, SF, and PS were measured. HR, RPE, and SF during forward and backward running decreased with increasing BWS (P<0.05).V̇O2 during both forward and backward running at 50%BWS was significantly lower than when running at 0%BWS (P<0.01). However, PS during forward and backward running increased with increasing BWS (P<0.01). Furthermore,V̇O2 was different between running directions only when running at 0%BWS (P<0.01). HR and RPE were not different between running directions (P>0.05). SF during backward running was higher than that of forward running (P<0.01). PS during backward running was lower than when running forward (P<0.001). Our observations suggest that individuals may select PS and SF during running with BWS in a way that resulted in similar metabolic costs, regardless of direction of locomotion.

Physiological Responses and Perceived Exertion During Robot-Assisted and Body Weight–Supported Gait After Stroke

Introduction. Physiological responses are rarely considered during walking after stroke and if considered, only during a short period (3-6 minutes). The aims of this study were to examine physiological responses during 30-minute robot-assisted and body weight–supported treadmill and overground walking and compare intensities with exercise guidelines. Methods. A total of 14 ambulatory stroke survivors (age: 61 ± 9 years; time after stroke: 2.8 ± 2.8 months) participated in 3 separate randomized walking trials. Patients walked overground, on a treadmill, and in the Lokomat (60% robotic guidance) for 30 minutes at matched speeds (2.0 ± 0.5 km/h) and matched levels of body weight support (BWS; 41% ± 16%). Breath-by-breath gas analysis, heart rate, and perceived exertion were assessed continuously. Results. Net oxygen consumption, net carbon dioxide production, net heart rate, and net minute ventilation were about half as high during robot-assisted gait as during body weight–supported treadmill and overground walking (P < .05). Net minute ventilation, net breathing frequency, and net perceived exertion significantly increased between 6 and 30 minutes (respectively, 1.8 L/min, 2 breaths/min, and 3.8 units). During Lokomat walking, exercise intensity was significantly below exercise recommendations; during body weight–supported overground and treadmill walking, minimum thresholds were reached (except for percentage of heart rate reserve during treadmill walking). Conclusion. In ambulatory stroke survivors, the oxygen and cardiorespiratory demand during robot-assisted gait at constant workload are considerably lower than during overground and treadmill walking at matched speeds and levels of body weight support. Future studies should examine how robotic devices can be Future studies should examine how robotic devices can be exploited to induce aerobic exercise.

Influence of the amount of body weight support on lower limb joints' kinematics during treadmill walking at different gait speeds: Reference data on healthy adults to define trajectories for robot assistance.

Several robotic devices have been developed for the rehabilitation of treadmill walking in patients with movement disorders due to injuries or diseases of the central nervous system. These robots induce coordinated multi-joint movements aimed at reproducing the physiological walking or stepping patterns. Control strategies developed for robotic locomotor training need a set of predefined lower limb joint angular trajectories as reference input for the control algorithm. Such trajectories are typically taken from normative database of overground unassisted walking. However, it has been demonstrated that gait speed and the amount of body weight support significantly influence joint trajectories during walking. Moreover, both the speed and the level of body weight support must be individually adjusted according to the rehabilitation phase and the residual locomotor abilities of the patient. In this work, 10 healthy participants (age range: 23-48 years) were asked to walk in movement analysis laboratory on a treadmill at five different speeds and four different levels of body weight support; besides, a trial with full body weight support, that is, with the subject suspended on air, was performed at two different cadences. The results confirm that lower limb kinematics during walking is affected by gait speed and by the amount of body weight support, and that on-air stepping is radically different from treadmill walking. Importantly, the results provide normative data in a numerical form to be used as reference trajectories for controlling robot-assisted body weight support walking training. An electronic addendum is provided to easily access to such reference data for different combinations of gait speeds and body weight support levels.

A Challenge-Based Approach to Body Weight-Supported Treadmill Training Poststroke: Protocol for a Randomized Controlled Trial.

BackgroundBody weight support treadmill training protocols in conjunction with other modalities are commonly used to improve poststroke balance and walking function. However, typical body weight support paradigms tend to use consistently stable balance conditions, often with handrail support and or manual assistance.ObjectiveIn this paper, we describe our study protocol, which involved 2 unique body weight support treadmill training paradigms of similar training intensity that integrated dynamic balance challenges to help improve ambulatory function post stroke. The first paradigm emphasized walking without any handrails or manual assistance, that is, hands-free walking, and served as the control group, whereas the second paradigm incorporated practicing 9 essential challenging mobility skills, akin to environmental barriers encountered during community ambulation along with hands-free walking (ie hands-free + challenge walking).MethodsWe recruited individuals with chronic poststroke hemiparesis and randomized them to either group. Participants trained for 6 weeks on a self-driven, robotic treadmill interface that provided body weight support and a safe gait-training environment. We assessed participants at pre-, mid- and post 6 weeks of intervention-training, with a 6-month follow-up. We hypothesized greater walking improvements in the hands-free + challenge walking group following training because of increased practice opportunity of essential mobility skills along with hands-free walking.ResultsWe assessed 77 individuals with chronic hemiparesis, and enrolled and randomized 30 individuals poststroke for our study (hands-free group=19 and hands-free + challenge walking group=20) from June 2012 to January 2015. Data collection along with 6-month follow-up continued until January 2016. Our primary outcome measure is change in comfortable walking speed from pre to post intervention for each group. We will also assess feasibility, adherence, postintervention efficacy, and changes in various exploratory secondary outcome measures. Additionally, we will also assess participant responses to a study survey, conducted at the end of training week, to gauge each group's training experiences.ConclusionsOur treadmill training paradigms, and study protocol represent advances in standardized approaches to selecting body weight support levels without the necessity for using handrails or manual assistance, while progressively providing dynamic challenges for improving poststroke ambulatory function during rehabilitation.Trial RegistrationClinicalTrials.gov NCT02787759; https://clinicaltrials.gov/ct2/show/NCT02787759 (Archived by Webcite at http://www.webcitation.org/6yJZCrIea)

Preserved gait kinematics during controlled body unloading

BackgroundBody weight supported locomotor training was shown to improve walking function in neurological patients and is often performed on a treadmill. However, walking on a treadmill does not mimic natural walking for several reasons: absent self-initiation, less active retraction of leg required and altered afferent input. The superiority of overground training has been suggested in humans and was shown in rats demonstrating greater plasticity especially in descending pathways compared to treadmill training. We therefore developed a body weight support system allowing unrestricted overground walking with minimal interfering forces to train neurological patients. The present study investigated the influence of different amounts of body weight support on gait in healthy individuals.MethodsKinematic and electromyographic data of 19 healthy individuals were recorded during overground walking at different levels of body weight support (0, 10, 20, 30, 40, and 50%). Upper body inclination, lower body joint angles and multi-joint coordination as well as time-distance parameters were calculated. Continuous data were analyzed with regard to distinct changes within a gait cycle across all unloading conditions.ResultsTemporal gait parameters were most sensitive to changes in body unloading while spatial variables (step length, joint angles) showed modest responses when unloaded by as much as 50% body weight. The activation of the gastrocnemius muscle showed a gradual decrease with increasing unloading while the biceps femoris muscle showed increased activity levels at 50% unloading. These changes occurred during stance phase while swing phase activity remained unaltered.ConclusionsHealthy individuals were able to keep their walking kinematics strikingly constant even when unloaded by half of their body weight, suggesting that the weight support system permits a physiological gait pattern. However, maintaining a given walking speed using close-to-normal kinematics while being unloaded was achieved by adapting muscle activity patterns. Interestingly, the required propulsion to maintain speed was not achieved by means of increased gastrocnemius activity at push-off, but rather through elevated biceps femoris activity while retracting the leg during stance phase. It remains to be investigated to what extent neurological patients with gait disorders are able to adapt their gait pattern in response to body unloading.

Effect of body weight support variation on muscle activities during robot assisted gait: a dynamic simulation study

Background and Objectives: While body weight support (BWS) intonation is vital during conventional gait training of neurologically challenged subjects, it is important to evaluate its effect during robot assisted gait training. In the present research we have studied the effect of BWS intonation on muscle activities during robotic gait training using dynamic simulations. Methods: Two dimensional (2-D) musculoskeletal model of human gait was developed conjointly with another 2-D model of a robotic orthosis capable of actuating hip, knee and ankle joints simultaneously. The musculoskeletal model consists of eight major muscle groups namely; soleus (SOL), gastrocnemius (GAS), tibialis anterior (TA), hamstrings (HAM), vasti (VAS), gluteus maximus (GLU), uniarticular hip flexors (iliopsoas, IP), and Rectus Femoris (RF). BWS was provided at levels of 0, 20, 40 and 60% during the simulations. In order to obtain a feasible set of muscle activities during subsequent gait cycles, an inverse dynamics algorithm along with a quadratic minimization algorithm was implemented. Results: The dynamic parameters of the robot assisted human gait such as joint angle trajectories, ground contact force (GCF), human limb joint torques and robot induced torques at different levels of BWS were derived. The patterns of muscle activities at variable BWS were derived and analysed. For most part of the gait cycle (GC) the muscle activation patterns are quite similar for all levels of BWS as is apparent from the mean of muscle activities for the complete GC. Conclusions: Effect of BWS variation during robot assisted gait on muscle activities was studied by developing dynamic simulation. It is expected that the proposed dynamic simulation approach will provide important inferences and information about the muscle function variations consequent upon a change in BWS during robot assisted gait. This information shall be quite important while investigating the influence of BWS intonation on neuromuscular parameters of interest during robotic gait training.

Body weight support impacts lateral stability during treadmill walking

Body weight support (BWS) systems are a common tool used in gait rehabilitation. BWS systems may alter the requirements for an individual to actively stabilize by 1) providing lateral restoring forces that reduce the requirements for the nervous system to actively stabilize and 2) decreasing the stabilizing gravitational moment in the frontal plane, which could increase the requirements to actively stabilize. The goal of the current study was to quantify the interaction between BWS and lateral stability. We hypothesized that when able-bodied people walk with BWS: 1) the lateral restoring forces provided by BWS would reduce the requirements to stabilize in the frontal plane when comparing dynamically similar gaits, and 2) increasing BWS would decrease the stabilizing gravitational moment in the frontal plane and increase the requirements to stabilize when speed is constrained. Our findings partly support these hypotheses, but indicate a complex interaction between BWS and lateral stability. With BWS, subjects significantly decreased step width variability and significantly increased step width (p<0.05) for both the dynamically similar and Speed-Matched conditions. The decrease in step width variability may be attributable to a combination of lateral restoring forces decreasing the mechanical requirements to stabilize and an enhanced sense of position that could have improved locomotor control. Increases in step width when walking with high levels of BWS could have been due to decreases in the gravitational moment about the stance limb, which may challenge the control of stability in multiple planes.

Biomechanical effects of body weight support with a novel robotic walker for over-ground gait rehabilitation.

Body weight support (BWS) promotes better functional outcomes for neurologically challenged patients. Despite the established effectiveness of BWS in gait rehabilitation, the findings on biomechanical effects of BWS training still remain contradictory. Therefore, the aim of this study is to comprehensively investigate the effects of BWS. Using a newly developed robotic walker which can facilitate pelvic motions with an active BWS unit, we compared gait parameters of ten healthy subjects during a 10-m walk with incremental levels of body weight unloading, ranging from 0 to 40% at 10% intervals. Significant changes in joint angles and gait temporospatial parameters were observed. In addition, the results of an EMG signal study showed that the intensity of muscle activation was significantly reduced with increasing BWS levels. The reduction was found at the ankle, knee, and hip joints in the sagittal plane as well as at the hip joint in the frontal plane. The results of this study provide an important indication of increased lateral body balance and greater stabilization in sagittal and frontal plane during gait. Our findings provide a better understanding of the biomechanical effects of BWS during gait, which will help guide the gait rehabilitation strategies.