Exoskeleton-Assisted Sit-to-Stand Training Improves Lower-Limb Function Through Modifications of Muscle Synergies in Subacute Stroke Survivors.

Abnormal muscle synergies during sit-to-stand (STS) transitions have been observed post-stroke, which are associated with deteriorated lower-limb function and mobility. Although exoskeletons have been used in restoring lower-limb function, their effects on muscle synergies and lower-limb motor recovery remain unclear. Here, we characterized normal muscle synergy patterns during STS activity in ten healthy adults as a reference, comparing with pathological muscle synergy patterns in ten participants with subacute stroke. Moreover, we assessed the effects of a 3-week exoskeleton-assisted STS training intervention on muscle synergies and clinical scores in seven stroke survivors. We also investigated correlations between neuromuscular complexity of muscle synergies and clinical scores. Our results showed that the STS task involved three motor modules representing distinct biomechanical functions among healthy subjects. In contrast, stroke participants showed 3 abnormal modules for the paretic leg and 2 modules for the non-paretic leg. After the intervention, muscle synergies partially shifted towards the normal pattern observed in healthy subjects on the paretic side. On the non-paretic side, the synergy modules increased to three and neuromuscular coordination improved. Furthermore, the significant intervention-induced increases in Fugl-Meyer Assessment of Lower Extremity and Berg Balance Scale scores were associated with improved muscle synergies on the non-paretic side. These results indicate that the paretic side demonstrates abnormal changes in muscle synergies post-stroke, while the non-paretic side can synergistically adapt to post-stroke biomechanical deviations. Our data show that exoskeleton-based training improved lower-limb function post-stroke by inducing modifications in muscle synergies.

Exoskeleton-Assisted Anthropomorphic Movement Training for the Upper Limb After Stroke: The EAMT Randomized Trial.

BACKGROUND: Robot-assisted arm training is generally delivered in the robot-like manner of planar or mechanical 3-dimensional movements. It remains unclear whether integrating upper extremity (UE) natural coordinated patterns into a robotic exoskeleton can improve outcomes. The study aimed to compare conventional therapist-mediated training to the practice of human-like gross movements derived from 5 typical UE functional activities managed with exoskeletal assistance as needed for patients after stroke. METHODS: In this randomized, single-blind, noninferiority trial, patients with moderate-to-severe UE motor impairment due to subacute stroke were randomly assigned (1:1) to receive 20 sessions of 45-minute exoskeleton-assisted anthropomorphic movement training or conventional therapy. Treatment allocation was masked from independent assessors, but not from patients or investigators. The primary outcome was the change in the Fugl-Meyer Assessment for Upper Extremity from baseline to 4 weeks against a prespecified noninferiority margin of 4 points. Superiority would be tested if noninferiority was demonstrated. Post hoc subgroup analyses of baseline characteristics were performed for the primary outcome. RESULTS: Between June 2020 and August 2021, totally 80 inpatients (67 [83.8%] males; age, 51.9±9.9 years; days since stroke onset, 54.6±38.0) were enrolled, randomly assigned to the intervention, and included in the intention-to-treat analysis. The mean Fugl-Meyer Assessment for Upper Extremity change in exoskeleton-assisted anthropomorphic movement training (14.73 points; [95% CI, 11.43-18.02]) was higher than that of conventional therapy (9.90 points; [95% CI, 8.15-11.65]) at 4 weeks (adjusted difference, 4.51 points [95% CI, 1.13-7.90]). Moreover, post hoc analysis favored the patient subgroup (Fugl-Meyer Assessment for Upper Extremity score, 23-38 points) with moderately severe motor impairment. CONCLUSIONS: Exoskeleton-assisted anthropomorphic movement training appears to be effective for patients with subacute stroke through repetitive practice of human-like movements. Although the results indicate a positive sign for exoskeleton-assisted anthropomorphic movement training, further investigations into the long-term effects and paradigm optimization are warranted. REGISTRATION: URL: https://www.chictr.org.cn; Unique identifier: ChiCTR2100044078.

Exploring the effects of skeletal architecture and muscle properties on bipedal standing in the common chimpanzee (Pan troglodytes) from the perspective of biomechanics.

Introduction: It is well known that the common chimpanzee, as both the closest living relative to humans and a facultative bipedal, has the capability of bipedal standing but cannot do so fully upright. Accordingly, they have been of exceeding significance in elucidating the evolution of human bipedalism. There are many reasons why the common chimpanzee can only stand with its hips-knees bent, such as the distally oriented long ischial tubercle and the almost absent lumbar lordosis. However, it is unknown how the relative positions of their shoulder-hip-knee-ankle joints are coordinated. Similarly, the distribution of the biomechanical characteristics of the lower-limb muscles and the factors that affect the erectness of standing as well as the muscle fatigue of the lower limbs remain a mystery. The answers are bound to light up the evolutional mechanism of hominin bipedality, but these conundrums have not been shed much light upon, because few studies have comprehensively explored the effects of skeletal architecture and muscle properties on bipedal standing in common chimpanzees. Methods: Thus, we first built a musculoskeletal model comprising the head-arms-trunk (HAT), thighs, shanks, and feet segments of the common chimpanzee, and then, the mechanical relationships of the Hill-type muscle-tendon units (MTUs) in bipedal standing were deduced. Thereafter, the equilibrium constraints were established, and a constrained optimization problem was formulated where the optimization objective was defined. Finally, thousands of simulations of bipedal standing experiments were performed to determine the optimal posture and its corresponding MTU parameters including muscle lengths, muscle activation, and muscle forces. Moreover, to quantify the relationship between each pair of the parameters from all the experimental simulation outcomes, the Pearson correlation analysis was employed. Results: Our results demonstrate that in the pursuit of the optimal bipedal standing posture, the common chimpanzee cannot simultaneously achieve maximum erectness and minimum muscle fatigue of the lower limbs. For uni-articular MTUs, the relationship between muscle activation, relative muscle lengths, together with relative muscle forces, and the corresponding joint angle is generally negatively correlated for extensors and positively correlated for flexors. For bi-articular MTUs, the relationship between muscle activation, coupled with relative muscle forces, and the corresponding joint angles does not show the same pattern as in the uni-articular MTUs. Discussion: The results of this study bridge the gap between skeletal architecture, along with muscle properties, and biomechanical performance of the common chimpanzee during bipedal standing, which enhances existing biomechanical theories and advances the comprehension of bipedal evolution in humans.

In pursuit of reconstructing missing human hands.

Exploring bio-intelligence of human limbs could provide a new perspective for reconstructing missing limbs.

Anthropomorphic Reaching Movement Generating Method for Human-Like Upper Limb Robot.

How to generate anthropomorphic reaching movement remains a challenging problem in service robots and human motor function repair/reconstruction equipment. However, there is no universally accepted computational model in the literature for reproducing the motion of the human upper limb. In response to the problem, this article presents a computational framework for generating reaching movement endowed with human motion characteristics that imitated the mechanism in the control and realization of human upper limb motions. This article first establishes the experimental paradigm of human upper limb functional movements and proposes the characterization of human upper limb movement characteristics and feature movement clustering methods in the joint space. Then, according to the specific task requirements of the upper limb, combined with the human sensorimotor model, the estimation method of the human upper limb natural postures was established. Next, a continuous task parametric model matching the characteristic motion class is established by using the Gaussian mixture regression method. The anthropomorphic motion generation method with the characteristics of the smooth trajectory and the ability of natural obstacle avoidance is proposed. Finally, the anthropomorphic motion generation method proposed in this article is verified by a human-like robot. The measurement index of the human-likeness degree of the trajectory is given. The experimental results show that for all four tested tasks, the human-likeness degrees were greater than 90.8%, and the trajectories' jerk generated by this method is very similar to the trajectories' jerk of humans, which validates the proposed method.

Preliminary Assessment of a Postural Synergy-Based Exoskeleton for Post-Stroke Upper Limb Rehabilitation.

Upper limb exoskeletons have drawn significant attention in neurorehabilitation because of the anthropomorphic mechanical structure analogous to human anatomy. Whereas, the training movements are typically unorganized because most exoskeletons ignore the natural movement characteristic of human upper limbs, particularly inter-joint postural synergy. This paper introduces a newly developed exoskeleton (Armule) for upper limb rehabilitation with a postural synergy design concept, which can reproduce activities of daily living (ADL) motion with the characteristics of human natural movements. The semitransparent active control strategy with the interactive force guidance and visual feedback ensured the active participation of users. Eight participants with hemiplegia due to a first-ever, unilateral stroke were recruited and included. They participated in exoskeleton therapy sessions for 4 weeks, with passive/active training under trajectories and postures with the characteristics of human natural movements. The primary outcome was the Fugl-Meyer Assessment for Upper Extremities (FMA-UE). The secondary outcomes were the Action Research Arm Test(ARAT), modified Barthel Index (mBI), and metric measured with the exoskeleton After the 4-weeks intervention, all subjects showed significant improvements in the following clinical measures: the FMA-UE (difference, 11.50 points, p = 0.002), the ARAT (difference, 7.75 points ), and the mBI (difference, 17.50 points, p = 0.003 ) score. Besides, all subjects showed significant improvements in kinematic and interaction force metrics measured with the exoskeleton. These preliminary results demonstrate that the Armule exoskeleton could improve individuals' motor control and ADL function after stroke, which might be associated with kinematic and interaction force optimization and postural synergy modification during functional tasks.

Robot-Assisted Arm Training in Stroke Individuals With Unilateral Spatial Neglect: A Pilot Study.

Background: Robot-assisted arm training (RAT) is an innovative exercise-based therapy that provides highly intensive, adaptive, and task-specific training, yet its effects for stroke individuals with unilateral spatial neglect remain to be explored. The study was aimed to investigate the effects of RAT on unilateral spatial neglect, arm motor function, activities of daily living, and social participation after stroke. Methods: In a pilot randomized controlled trial, individuals with unilateral spatial neglect after right hemisphere stroke were equally allocated to intervention group and control group, 45-min training daily, 5 days/week, for 4 weeks. Outcome measures included the Behavioral Inattention Test-conventional section (BIT-C), Catherine Bergego Scale (CBS), Fugl-Meyer Assessment for Upper Extremity (FMA-UE), Modified Barthel Index (MBI), and World Health Organization Disability Assessment Schedule Version 2.0 (WHODAS 2.0). Results: From November 2018 to February 2021, 20 stroke patients (mean age 47.40 ± 8.47) were enrolled in the study. Robot-assisted arm training was feasible and safe for individuals with unilateral spatial neglect. Both groups had significant improvements in all outcome measures. Participants assigned to RAT therapy had significantly greater improvements in BIT-C (difference, 7.70; 95% CI, 0.55-14.85, P = 0.04), FMA-UE (difference, 5.10; 95% CI, 1.52-8.68, P = 0.01), and WHODAS 2.0 (difference, -7.30; 95% CI, -12.50 to -2.10, P = 0.01). However, the change scores on CBS and MBI demonstrated no significance between the groups. Conclusion: Our findings provide preliminary support for introducing robot-assisted arm training to remediate unilateral spatial neglect after stroke. The training program focusing on neglect of contralateral space and affected upper extremity may be effective in neglect symptoms, motor function recovery, and social participation, while not generalizing into improvements in activities of daily living. Clinical Trial Registration: Chinese Clinical Trial Registry (http://www.chictr.org.cn/) on 17 October 2019, identifier: ChiCTR1900026656.

Exoskeleton-Assisted Anthropomorphic Movement Training (EAMT) for Poststroke Upper Limb Rehabilitation: A Pilot Randomized Controlled Trial.

OBJECTIVE: To investigate the feasibility of exoskeleton-assisted anthropomorphic movement training (EAMT) and its effects on upper extremity motor impairment, function, and kinematics after stroke. DESIGN: A single-blind pilot randomized controlled trial. SETTING: Stroke rehabilitation inpatient unit. PARTICIPANTS: Participants with a hemiplegia (N=20) due to a first-ever, unilateral, subacute stroke who had a score of 8-47 on the Fugl-Meyer Assessment for Upper Extremity (FMA-UE). INTERVENTIONS: The exoskeleton group received EAMT therapy that provided task-specific training under anthropomorphic trajectories and postures. The control group received conventional upper limb therapy. For both groups, therapy was delivered at the same intensity, frequency, and duration: 45 minutes daily, 5 days per week, for 4 weeks. MAIN OUTCOME MEASURES: Primary outcome: feasibility analysis. SECONDARY OUTCOMES: FMA-UE, Action Research Arm Test (ARAT), modified Barthel Index (MBI), and kinematic metrics during exoskeleton therapy. RESULTS: Twenty participants with subacute stroke were recruited and completed all therapy sessions. EAMT therapy was feasible and acceptable for the participants. The recruitment rate, retention rate, and number of therapists required for EAMT therapy were acceptable compared with other robotic trials. EAMT was determined to be safe, as no adverse event occurred except tolerable muscle fatigue in 2 participants. There were significant between-group differences in the change scores of FMA-UE (difference, 4.30 points; P=.04) and MBI (difference, 8.70 points; P=.03) in favor of EAMT therapy. No significant between-group difference was demonstrated for the change scores of ARAT (P=.18). Participants receiving EAMT showed significant improvements in kinematic metrics after treatment (P<.01). CONCLUSIONS: Our results indicate that EAMT is a feasible approach and may improve upper extremity motor impairment, activities of daily living, and kinematics after stroke. However, fully powered randomized controlled trials are warranted to confirm the results of this pilot study and explore the underlying mechanisms by which EAMT therapy might work.

Association Between Finger-to-Nose Kinematics and Upper Extremity Motor Function in Subacute Stroke: A Principal Component Analysis.

BACKGROUND: Kinematic analysis facilitates interpreting the extent and mechanisms of motor restoration after stroke. This study was aimed to explore the kinematic components of finger-to-nose test obtained from principal component analysis (PCA) and the associations with upper extremity (UE) motor function in subacute stroke survivors. METHODS: Thirty-seven individuals with subacute stroke and twenty healthy adults participated in the study. Six kinematic metrics during finger-to-nose task (FNT) were utilized to perform PCA. Clinical assessments for stroke participants included the Fugl-Meyer Assessment for Upper Extremity (FMA-UE), Action Research Arm Test (ARAT), and Modified Barthel Index (MBI). RESULTS: Three principal components (PC) accounting for 91.3% variance were included in multivariable regression models. PC1 (48.8%) was dominated by mean velocity, peak velocity, number of movement units (NMU) and normalized integrated jerk (NIJ). PC2 (31.1%) described percentage of time to peak velocity and movement time. PC3 (11.4%) profiled percentage of time to peak velocity. The variance explained by principal component regression in FMA-UE (R 2 = 0.71) were higher than ARAT (R 2 = 0.59) and MBI (R 2 = 0.29) for stroke individuals. CONCLUSION: Kinematic components during finger-to-nose test identified by PCA are associated with UE motor function in subacute stroke. PCA reveals the intrinsic association among kinematic metrics, which may add value to UE assessment and future intervention targeted for kinematic components for stroke individuals. CLINICAL TRIAL REGISTRATION: Chinese Clinical Trial Registry (http://www.chictr.org.cn/) on 17 October 2019, identifier: ChiCTR1900026656.

Working out the bipedal walking expenditure of energy based on foot morphology of different hominid genera: Implications for foot evolution.

Among the Hominidae family of primates, Homo is characterized by more economical bipedal walking. Over the course of evolution towards bipedalism, the foot becomes the only organ directly interacting with substrate and likely influence the bipedal walking economy. However, working out the energy expenditure in bipedal walking from the specific aspect of foot morphology is still challenging, which hinders the understanding of the evolution of both hominid feet and economical bipedal walking. Here we present a functional model to quantitatively assess bipedal walking expenditure of energy from hominid foot morphology. According to our results, the feet of Homo are most suited to economical bipedal walking among hominids. However, the genus whose feet possess second best ability for economical bipedal walking is not our closest relative Pan, but is Gorilla. Using phylogenetically informed morphometric analyses, we further infer the evolutionary changes of hominid foot morphology and investigate the corresponding variation of bipedal walking expenditure. Our results reveal the economical bipedal walking benefits from the morphological changes of human foot after descending from the last common ancestor of hominids. Conversely, the foot morphologies of great apes reflect selections for other locomotor modes, at cost of larger energy expenditure in bipedal walking.

Second-order bipartite consensus for networked robotic systems with quantized-data interactions and time-varying transmission delays.

This paper investigates the second-order bipartite consensus (BC) problems for networked robotic systems (NRSs) subject to model uncertainties and external disturbances over signed directed graphs. We have newly presented two classes of hierarchical control algorithms (HCAs) to solve the BC problems for NRSs in a more practical and challenging case of quantized-data interactions (QDIs) and time-varying transmission delays (TVTDs). By using Hurwitz criterion and Lyapunov stability argument, several sufficient conditions on control parameters are obtained and the BC performance of the regulated system is analyzed. Three examples validate the presented theoretical findings.

A science-driven method for determining morphological parameters of prosthetic hands.

The unique morphological bases of human hands, which are distinct from other primates, endow them with excellent grasping and manipulative abilities. However, the lack of understanding of human hand morphology and its parametric features is a major obstacle in the scientific design of prosthetic hands. Existing designs of prosthetic hand morphologies mostly adopt engineering-based methods, which depend on human experience, direct measurements of human hands, or numerical simulation/optimization. This paper explores for the first time a science-driven design method for prosthetic hand morphology, aiming to facilitate the development of prosthetic hands with human-level dexterity. We first use human morphological, movement, and postural data to quantitatively cognize general morphological characteristics of human hands in static, dynamic, functional, and non-functional perspectives. Taking these cognitions as bases, we develop a method able to quickly transfer human morphological parameters to prosthetic hands and endow the prosthetic hands with great grasping/manipulative potential at the same time. We apply this method to the design of an advanced prosthetic hand (called X-hand II) embedded with compact actuating systems. The human-size prosthetic hand can reach wide grasping/manipulative ranges close to those of human hands, replicate various daily grasping types and even execute dexterous in-hand manipulation. This science-driven method may also inspire other artificial limb and bionic robot designs.

Alleviation of Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome in Rats by Yiqi Huayu Jiedu Decoction: A Tandem Mass Tag-Based Proteomics Study.

BACKGROUND: To study the effect of Yiqi Huayu Jiedu Decoction (YQHYJD) on protein expression in the lung tissue of acute respiratory distress syndrome (ARDS) rats and to explore the underlying molecular therapeutic mechanism of YQHYJD. METHODS: Sprague Dawley rats were administered with YQHYJD by oral gavage for 1 week. The rats were injected with lipopolysaccharide (LPS) to induce ARDS. The lung injury was assessed pathologically. Differentially expressed proteins (DEPs) were screened by quantitative proteomics and analyzed using bioinformatic tools, such as Metascape and Kyoto Encyclopedia of Genes and Genomes (KEGG) mapper. DEPs were verified by parallel reaction monitoring (PRM). RESULTS: YQHYJD alleviated the LPS-induced pathological damage of lung tissue in rats. There were 134 DEPs among the YQHYJD treatment and model groups. The Genomes pathway analyses revealed that the DEPs were closely related to immune system pathway. The mass spectrometry analysis revealed that YQHYJD exhibits a protective effect on lung tissue by significantly upregulating hematopoietic cell kinase (Hck), phospholipid phosphatase 3 (Plpp3), myristoylated-alanine rich C-kinase substrate (Marcks), and Actin-related protein 2/3 complex subunit 2 (Arpc2), which are related to Fc gamma receptor-mediated phagocytosis pathway. CONCLUSION: YQHYJD can alleviate the lung injury of ARDS rats by regulating the Fc gamma receptor-mediated phagocytosis pathway, which is related to immune system.

Exploring the existence of better hands for manipulation than the human hand based on hand proportions.

Human exhibits the most dexterous manual manipulation among the anthropoids. The sophisticated dexterity of human hand has been linked to its distinctive morphology compared to the nonhuman anthropoids. The human hand is derived from the ancestral hands after longtime evolution. However, there are more possible morphologies that the hands could take during the evolutionary process. It remains unknown whether better hands for manipulation than the human hand exist among these possible hands. To answer the question, the relationship between the manipulative capability and hand morphology need to be investigated in the region of more possible hands. Here we employ a kinematic model to quantitatively assess the manipulative ability of the possible hands from the aspect of hand proportions. The segment length proportions of each possible hand are reconstructed by the major evolutionary patterns of the anthropoid hands. Our results reveal that too long and too short thumbs relative to fingers both hamper the manual dexterity, though the long thumb of human hand is traditionally thought to be beneficial to manipulation. The results promote the understanding of the link between hand morphology and function. Furthermore, we find out the optimal hand for dexterous manipulation within the region reconstructed by the major evolutionary patterns of the anthropoid hands. The optimal hand is more dexterous than the human hand. Compared to the optimal hand, the human hand has shorter metacarpals relative to phalanges, which is thought to be advantageous to the prehensility. It suggests that the human hand is not an organ exclusive for the dexterous manipulation, but a trade-off between multiple functions.

Assessing the manipulative potentials of monkeys, apes and humans from hand proportions: implications for hand evolution.

The hand structure possesses a greater potential for performing manipulative skills than is typically observed, whether in humans or non-human anthropoids. However, a precise assessment of the potential manipulative skills of hands has been challenging, which hampers our understanding of the evolution of manipulative abilities in anthropoid hands. Here, we establish a functional model to quantitatively infer the manipulative potentials of anthropoid hands based on hand proportions. Our results reveal a large disparity of manipulative potentials among anthropoid hands. From the aspect of hand proportions, the human hand has the best manipulative potential among anthropoids. However, the species with a manipulative potential closer to that of humans are not our nearest relatives, chimpanzees, but rather, are certain monkey species. In combination with the phylogenetically informed morphometric analyses, our results suggest that the morphological changes of non-human anthropoid hands did not coevolve with the brain to facilitate the manipulative ability during the evolutionary process, although the manipulative ability is a survival skill. The changes in non-human anthropoid hands may have more likely evolved under selective pressure for locomotion than manipulation.

Biomechanical Characteristics of Hand Coordination in Grasping Activities of Daily Living.

Hand coordination can allow humans to have dexterous control with many degrees of freedom to perform various tasks in daily living. An important contributing factor to this important ability is the complex biomechanical architecture of the human hand. However, drawing a clear functional link between biomechanical architecture and hand coordination is challenging. It is not understood which biomechanical characteristics are responsible for hand coordination and what specific effect each biomechanical characteristic has. To explore this link, we first inspected the characteristics of hand coordination during daily tasks through a statistical analysis of the kinematic data, which were collected from thirty right-handed subjects during a multitude of grasping tasks. Then, the functional link between biomechanical architecture and hand coordination was drawn by establishing the clear corresponding causality between the tendinous connective characteristics of the human hand and the coordinated characteristics during daily grasping activities. The explicit functional link indicates that the biomechanical characteristic of tendinous connective architecture between muscles and articulations is the proper design by the Creator to perform a multitude of daily tasks in a comfortable way. The clear link between the structure and the function of the human hand also suggests that the design of a multifunctional robotic hand should be able to better imitate such basic architecture.

[Determination of available as (III) and as (V) in soils by flow injection hydride generation atomic fluorescence spectrometry].

A method for the determination of available As (III) and As (V) in soils by flow injection hydride generation atomic fluorescence spectrometry (FI-HG-AFS) was presented. As the concentration of As (III) in extract was determined by HG-AFS in the medium of 0.1 mol.L-1 citric acid solution and the total arsenic was determined after FI on-line reduction of As (V) by L-cysteine, the concentration of As (V) was calculated by the difference. The manifolds for FI on-line reduction of As (V) were designed. The chemical conditions and the operating parameters were optimized. The detection limits (3 sigma) of As (III) and As (V) are 0.11 and 0.07 ng.mL-1, respectively, and the relative standard deviation is 1.43 for 7 determinations of 10 ng.mL-1 As (III) solution. The developed method was applied to the determination of available As (III) and As (V) in real soils and the recovery was 82%-104%.