Compensatory Movements Research Articles

Overhead squat assessment reflects treadmill running kinematics

PurposeOverhead squat assessment (OHSA) is a pre-activity dynamic movement analysis tool used to define deviations from an ideal motion pattern which known as compensation. Compensatory movements may result from abnormality in myofascial activity, length-tension relationships, neuro-motor control strategies, osteokinematics and arthrokinematics. The aim of this study is to identify the association between selected biomechanical variables of the ankle, knee, hip, pelvis, torso during OHSA and 16 km/h treadmill running tasks.MethodsThirteen national long distance male runners (17.3 ± 0.5 age (years); 5.89 ± 1.95 experience (years), 57.9 ± 3.7 body mass (kg); 175.4 ± 5.7 height (cm)) participated in this 2controlled laboratory study. Three-dimensional kinematics were collected at 250 Hz using a 9-camera Qualisys motion analysis system (Qualisys AB, Goteborg, Sweden) while participants performed 16 km/h treadmill running and OHSA tasks.ResultsCorrelation coefficients demonstrated that OHSA pelvic anterior tilt angle was in a positive association with foot strike (FS), mid-stance (MS), and toe-off (TO) pelvic anterior tilt angles and MS tibial internal rotation on talus, MS ankle pronation, MS hip internal rotation. OHSA pelvic anterior tilt angle was in a negative association with TO hip extension. OHSA maximal hip adduction was positively correlated with MS and stance maximal knee adduction. FS, MS, stance maximal angular dorsiflexion values were positively correlated with OHSA dorsiflexion. Increased OHSA dorsiflexion angle was negatively associated with TO plantar flexion. OHSA pronation was positively associated with MS and stance pronation. MS hip internal rotation, MS hip adduction angles were increased, and MS ankle dorsiflexion was significantly decreased with the increase of trunk forward lean relative to tibia during OHSA.ConclusionsOHSA was associated with some important and dysfunction-related hip, knee and ankle kinematics. Running coaches, may use OHSA as an assessment tool before the corrective training plan to detect injury-related compensation patterns to reduce the risk of injury and improve running technique.

MuRF-1 is Involved in Laryngeal Muscle Denervation Atrophy by Regulating G-Actin Ubiquitination.

Muscle RING-finger protein-1 (MuRF-1), an E3 ubiquitin ligase, has been reported to aggravate skeletal muscle denervated atrophy by mediating the ubiquitination degradation of multiple proteins, whereas the molecular mechanism underlying MuRF-1-mediated internal laryngeal muscle denervated atrophy remains unknown. A rat unilateral recurrent laryngeal nerve (RLN) transection model was established to evaluate denervated muscle atrophy of the larynx. The expression of MuRF-1, G- and F-actin in thyroarytenoid muscle (TA) myocytes before and after RLN injury was analyzed by immunofluorescence and Western blotting. Coimmunoprecipitation experiments detected molecular interactions between MuRF-1 and G-actin. Immunoprecipitation tested MuRF-1-mediated ubiquitination of G-actin in denervated and innervated TA muscle tissues. The shRNA-MuRF-1 AAV was used to suppress MuRF-1 expression in denervated TA muscles in vivo. First, MuRF-1 expression was significantly elevated in denervated TA muscle compared to innervated TA muscle (p < 0.001). Second, there was a progressive increase in the G/F-actin ratio in TA myocytes from day 3 to 14 after RLNI (p < 0.01). Furthermore, colocalization of MuRF-1 and G-actin in denervated TA myocytes was observed. Moreover, the upregulation of MuRF-1 was closely associated with the ubiquitination of G-actin in denervated TA myocytes and muscle tissues. Knockdown of MuRF-1 decelerated the degree of TA muscle atrophy compared with that in the Blank and NC groups (p < 0.001) but seemed to promote the compensatory movement of the healthy side. Collectively, we illustrate a novel molecular mechanism underlying MuRF-1-mediated internal laryngeal muscle denervated atrophy in that MuRF-1 could promote disequilibrium of the G/F-actin ratio by regulating G-actin ubiquitination. NA Laryngoscope, 134:855-864, 2024.

Poor functional task performance and compensatory trunk movements remain two years after total knee arthroplasty

Poor functional task performance and compensatory trunk movements remain two years after total knee arthroplasty

Prosthetic Stimulation of the Vestibular Nerve Can Evoke Robust Eye and Head Movements Despite Prior Labyrinthectomy.

Prosthetic electrical stimulation can evoke compensatory eye and head movement despite vestibular implant electrode insertion occurring years after prior labyrinthectomy. Vestibular implants sense head rotation and directly stimulate the vestibular nerve, bypassing damaged end organs. Animal research and current clinical trials have demonstrated the efficacy of this approach. However, candidacy criteria for vestibular implants currently require presence of a patent labyrinth in the candidate ear and at least aidable hearing in the opposite ear, thus excluding patients who have undergone prior labyrinthectomy for unilateral Menière's disease that later progressed to bilateral vestibular hypofunction. Eight years after right unilateral labyrinthectomy, we implanted stimulating electrodes in the previously exenterated right ear ampullae of a rhesus macaque monkey. The left labyrinth had long-standing hypofunction due to intratympanic gentamicin injection and surgical disruption. We used three-dimensional video-oculography to measure eye movement responses to prosthetic electrical stimulation. We also measured head-movement responses to prosthetic stimulation with the head unrestrained. Bilateral vestibular hypofunction was confirmed by absence of vestibuloocular reflex responses to whole-body rotation without prosthetic stimulation. For a subset of the implanted electrodes, prosthetic vestibular stimulation evoked robust compensatory eye and head movements. One electrode reliably elicited responses aligned with the implanted ear's anterior canal nerve regardless of the return electrode used. Similarly, a second electrode also elicited responses consistent with excitation of the horizontal canal nerve. Responses grew quasilinearly with stimulation rate and current amplitude. Prosthetic electrical stimulation targeting the vestibular nerve can be effective years after labyrinthectomy, if at least some parts of the vestibular nerve's ampullary branches remain despite destruction or removal of the membranous labyrinth.

Kinematic analysis of movement patterns during a reach-and-grasp task in stroke patients.

This study aimed to evaluate the kinematic movement patterns during a reach-and-grasp task in post-stroke patients according to the upper extremity impairment severity. Subacute stroke patients (n = 46) and healthy controls (n = 20) were enrolled in this study. Spatiotemporal and kinematic data were obtained through 3D motion analysis during the reach-and-grasp task. Stroke patients were grouped using the Fugl-Meyer Assessment (FMA) scale, and a comparison of the groups was performed. The severe group showed a significantly longer movement time, lower peak velocity, and higher number of movement units than the mild group during the reach-and-grasp task (p < 0.05). Characteristic compensatory movement patterns, such as shoulder abduction, thoracic posterior tilting, and upward and external rotation were significantly greater during the forward transporting phase in the severe group than in the mild group (p < 0.05). The FMA score was significantly associated with the movement time during the forward transporting phase, number of movement units during the reaching phase, range of shoulder abduction-adduction and wrist flexion-extension movements during the reaching phase, and range of thoracic internal-external rotation during the backward transporting phase (p < 0.05). Post-stroke patients have unique spatiotemporal and kinematic movement patterns during a reach-and grasp-task according to the impairment severity.

Examining the Effect of Time-From-Treatment on Activities of Daily Living Kinematics in Breast Cancer Survivors.

Breast cancer affects one in 8 females with a 5-year survival rate of 89%. Up to 72% of breast cancer survivors have trouble with activities of daily living (ADL) following treatment. Increased time-from-treatment improves some measures of function, yet ADL limitations persist. Therefore, this study assessed the effect of time-from-treatment on upper extremity kinematics during ADLs in breast cancer survivors. Twenty-nine female breast cancer survivors were divided into 2 groups: <1year (n = 12) and 1-2years (n = 17) from treatment. Kinematics were collected during 6 ADL tasks, and humerothoracic joint angles were quantified. A 2-way mixed analysis of variance assessed the effects of time-from-treatment and arm on maximum angles for each ADL. Decreased maximum angle existed for breast cancer survivors with increased time-from-treatment during all ADLs. Breast cancer survivors in the 1-2years group used ∼28° to 32° lower elevation, ∼14° to 28° lower axial rotation, and ∼10° to 14° lower plane of elevation range across tasks. Decreased ranges of arm movement during ADLs with increased time-from-treatment may reflect compensatory movement strategies. Recognizing this shift in strategies and accompanying underlying disease progression can help inform responses to functional performance limitations in breast cancer survivors as delayed effects are present posttreatment.

Combining spinal neuromodulation and activity based neurorehabilitation therapy improves sensorimotor function in cerebral palsy.

Motor dysfunction in individuals with cerebral palsy (CP) such as the inability to initiate voluntary movements, walking with compensatory movement patterns, and debilitating spasticity is due to the aberrant neural connectivity between the brain and spinal cord. We tested the efficacy of noninvasive spinal cord neuromodulation (SCiP™, SpineX Inc.) with activity-based neurorehabilitation therapy (ABNT) in improving the sensorimotor function in six children with CP. Children received 8 weeks of either SCiP™ or sham therapy with ABNT (n = 3 per group). At the end of 8 weeks, all participants received 8 weeks of SCiP™ therapy with ABNT. Follow up assessments were done at week 26 (10 weeks after the last therapy session). Sensorimotor function was measured by the Gross Motor Function Measure 88 (GMFM88) test. We observed minimal change in sham group (mean 6% improvement), however, eight weeks of SCiP™ therapy with ABNT resulted in statistically and clinically relevant improvement in GMFM88 scores (mean 23% increase from baseline). We also observed reduced scores on the modified Ashworth scale only with SCiP™ therapy (-11% vs. +5.53% with sham). Similar improvements were observed in sham group but only after the cross over to SCiP™ therapy group at the end of the first eight weeks. Finally, sixteen weeks of SCiP™ therapy with ABNT resulted in further improvement of GMFM88 score. The improvement in GMFM88 scores were maintained at week 26 (10 weeks after the end of therapy), suggesting a sustained effect of SCiP™ therapy.

Role of raising the upper limb of the non-rising side when performing rising movements from bed

Rising movements from bed comprise an important aspect of recovery from the bedridden state; however, they have not been sufficiently investigated using motion analysis studies. In particular, the effect of using the upper limb of the non-rising side before waist flexion on rising movements remains to be analyzed; this study aimed to clarify this effect. Accordingly, motion analyses were performed on rising movements under two constraint conditions, namely raising the upper limb of the non-rising side (upper limb use-condition) and keeping it in contact with the pelvis (upper limb non-use-condition); subsequently, the kinematics and kinematics parameters were compared. In comparison with the upper limb use-condition, in the upper limb non-use-condition, the distance traveled by the center of mass of the body (CoM trajectory, p < 0.01) increased while switching from the half-side-lying to on-hand postures, horizontal body movement (movement speed (Normalized time/total time), p < 0.01 and weight of center of body mass (CoM momentum in horizontal plane), p < 0.05) during the same period increased, and the half-side-lying time approached the peak value of the waist flexion angular velocity (Time lag between from half-side-lying to waist angler peak velocity, p < 0.05). The compensatory movement that occurred due to the upper limb non-use-condition denoted an increase in body momentum in the horizontal direction, rather than in the sagittal plane. Therefore, the upper limb on the non-rising side contributed to the smooth movement of the body in the horizontal direction. Moreover, this study demonstrated that asymmetrical rising movement in the diagonal direction is a characteristic movement wherein the horizontal movement of the body constitutes the main movement.

Online detection of compensatory strategies in human movement with supervised classification: a pilot study.

Stroke survivors often compensate for the loss of motor function in their distal joints by altered use of more proximal joints and body segments. Since this can be detrimental to the rehabilitation process in the long-term, it is imperative that such movements are indicated to the patients and their caregiver. This is a difficult task since compensation strategies are varied and multi-faceted. Recent works that have focused on supervised machine learning methods for compensation detection often require a large training dataset of motions with compensation location annotations for each time-step of the recorded motion. In contrast, this study proposed a novel approach that learned a linear classifier from energy-based features to discriminate between healthy and compensatory movements and identify the compensating joints without the need for dense and explicit annotations. Six healthy physiotherapists performed five different tasks using healthy movements and acted compensations. The resulting motion capture data was transformed into joint kinematic and dynamic trajectories. Inspired by works in bio-mechanics, energy-based features were extracted from this dataset. Support vector machine (SVM) and logistic regression (LR) algorithms were then applied for detection of compensatory movements. For compensating joint identification, an additional condition enforcing the independence of the feature calculation for each observable degree of freedom was imposed. Using leave-one-out cross validation, low values of mean brier score (<0.15), mis-classification rate (<0.2) and false discovery rate (<0.2) were obtained for both SVM and LR classifiers. These methods were found to outperform deep learning classifiers that did not use energy-based features. Additionally, online classification performance by our methods were also shown to outperform deep learning baselines. Furthermore, qualitative results obtained from the compensation joint identification experiment indicated that the method could successfully identify compensating joints. Results from this study indicated that including prior bio-mechanical information in the form of energy based features can improve classification performance even when linear classifiers are used, both for offline and online classification. Furthermore, evaluation compensation joint identification algorithm indicated that it could potentially provide a straightforward and interpretable way of identifying compensating joints, as well as the degree of compensation being performed.

Application of Deep Learning Algorithm to Monitor Upper Extremity Task Practice.

Upper extremity hemiplegia is a serious problem affecting the lives of many people post-stroke. Motor recovery requires high repetitions and quality of task-specific practice. Sufficient practice cannot be completed during therapy sessions, requiring patients to perform additional task practices at home on their own. Adherence to and quality of these home task practices are often limited, which is likely a factor reducing rehabilitation effectiveness post-stroke. However, home adherence is typically measured by self-reports that are known to be inconsistent with objective measurement. The objective of this study was to develop algorithms to enable the objective identification of task type and quality. Twenty neurotypical participants wore an IMU sensor on the wrist and performed four representative tasks in prescribed fashions that mimicked correct, compensatory, and incomplete movement qualities typically seen in stroke survivors. LSTM classifiers were trained to identify the task being performed and its movement quality. Our models achieved an accuracy of 90.8% for task identification and 84.9%, 81.1%, 58.4%, and 73.2% for movement quality classification for the four tasks for unseen participants. The results warrant further investigation to determine the classification performance for stroke survivors and if quantity and quality feedback from objective monitoring facilitates effective task practice at home, thereby improving motor recovery.

DMVC: Decomposed Motion Modeling for Learned Video Compression

Inter prediction is the critical component in hybrid coding framework to deal with the temporal redundancy. Most of the neural video coding methods typically follow the motion compensation based inter coding scheme, establishing motion vector (MV) as the central role. In this paper, we innovatively propose an efficient motion modeling approach by inherently decomposing it into two components, the intrinsic motion and the compensatory motion. The intrinsic motion originates from the implicit spatiotemporal context hidden in the historical sequence, which can be intuitively captured free of bits. On the top of it, the compensatory motion acts a role of structural refinement and texture enhancement as a form of side information. In particular, the inter prediction is performed in the feature space as a manner of progressive temporal transition, conditioned on the decomposed motion. By the motion decomposition paradigm, we innovatively answer the question of motion representation, compensation and coding in the learned video compression framework. With the temporal prediction, the remaining pixel residue is signaled to obtain the reconstruction. Extensive experimental results demonstrate that the proposed method achieves state-of-the-art coding performance on par with other end-to-end coding methods, and outperforms versatile video coding (VVC) under low-delay P (LDP) configuration in terms of MS-SSIM metric.

A theoretical framework of information preservation method and its application to low-speed nonequilibrium gas flows

Simulations of nonequilibrium gas flows have garnered significant interest in modern engineering problems involving rarefied gas flow characteristics. Despite the popularity of the direct simulation Monte Carlo (DSMC) method in simulating such flows, its use in low-speed flows is limited by statistical noises. The information preservation (IP) method is a promising alternative known for its low noise properties. In this study, a new theoretical framework for the IP method based on kinetic theory is introduced to offer complete understanding for the transport properties of the preserved information. Specifically, we introduce a velocity-information joint distribution function (VIJDF) and derive its governing equation as well as the corresponding macroscopic transport equations. To ensure the accuracy of the IP method, the total stress/heat flux in IP, including information stress/heat flux generated during movement and collision steps and compensation stress/heat flux imposed in the compensation step, is matched to the molecular stress/heat flux in DSMC. To this end, a nonequilibrium model for the VIJDF is proposed to evaluate the compensation stress/heat flux. The parameters in the collision model of IP are theoretically determined by equating the transport coefficients associated with the preserved information to the coefficients of viscosity and thermal conductivity in DSMC. Numerical simulations for a variety of nonequilibrium gas flows, including low-speed Couette flow, Fourier flow, high-speed Couette flow, external force-driven Poiseuille flow, lid-driven cavity flow, and thermal creep flow, demonstrate that the IP method can achieve similar accuracy as the DSMC method with a much smaller sampling size.

Above knee socket prosthesis use changes proximal femur morphology.

Patients with transfemoral amputation (TFA) are up to six times more likely to develop hip osteoarthritis (OA) in either or both the intact and residual limb, which is primarily attributed to habitually altered joint loading due to compensatory movement patterns. However, joint loading patterns differ between limbs, which confounds the understanding of loading-induced OA etiology across limbs. It remains unknown if altered loading due to amputation results in bony shape changes at the hip, which is a known etiological factor in the development of hip OA. Retrospective computed tomography images were collected of the residual limb for 31 patients with unilateral TFA (13F/18M; age: 51.7±9.9 y/o; time since amputation: 13.7±12.4years) and proximal femur for a control group of 29 patients (13F/16M; age: 42.0±12.27years) and used to create 3D geometries of the proximal femur. Femoral 3D geometric variation was quantified using statistical shape modeling (SSM), a computational tool which placed 2048 corresponding particles on each geometry. Independent modes of variation were created using principal component analysis. 2D radiographic measures of the proximal femur, including common measures such as α-angle, head neck offset, and neck shaft angle, were quantified on digitally reconstructed radiographs (DRRs). SSM results were then compared to 2D measures using Pearson correlation coefficients (r). Two-sample t-tests were used to determine if there were significant differences between the TFA and control group means of 2D radiographic measurements (p<0.05). Patients with TFA had greater femoral head asphericity within the SSM, which was moderately correlated to head-neck offset (r=-0.54) and α-angle (r=0.63), as well as greater trochanteric torsion, which was strongly correlated to the novel radiographic measure of trochanteric torsion (r=-0.78), compared to controls. For 2D measures, the neck-shaft angle was smaller in the TFA group compared to the control group (p=0.01) while greater trochanter height was larger in the TFA group compared to the control group (p=0.04). These results indicate altered loading from transfemoral prosthesis use changes proximal femur bony morphology, including femoral head asphericity and greater trochanter changes. Greater trochanter morphologic changes, though not a known factor to OA, affect moment arm and line of action of the primary hip abductors, the major muscles which contribute to joint loading and hip stability. Thus, chronic altered loading of the amputated limb hip, whether under- or overloading, results in bony changes to the proximal femur which may contribute to the etiological progression and development of OA.

Congenital bilateral radioulnar synostosis: A rare case report with review of literature

Congenital radioulnar synostosis (CRUS) is a rare anomaly of the upper limb which causes varying degrees of limitations in forearm rotations. It most commonly presents at the age of 6 years when the child starts going to school with difficulty in day-to-day activities. A 5-year-old male child presented to the outpatient department with complains of difficulty in forearm supination bilaterally. Plain radiography showed proximal radioulnar synostosis of 5 cm on both sides. He was managed conservatively with physiotherapy, occupational therapy, activity modification, and counseled about following up if no improvement occurred, in 2 years. CRUS can present as an isolated anomaly and is easily missed as it usually does not cause significant cosmetic concern and the child learns to overcome the deficits in forearm movements by compensatory movements at the shoulder and distal radioulnar joint. Diagnostic imaging plays a major role in identifying and planning management.

Placebo effect after visual restitution training: no eye-tracking controlled perimetric improvement after visual border stimulation in late subacute and chronic visual field defects after stroke.

A significant number of Restitution Training (RT) paradigms claim to ameliorate visual field loss after stroke by re-activating neuronal connections in the residual visual cortex due to repeated bright light-stimulation at the border of the blind and intact fields. However, the effectiveness of RT has been considered controversial both in science and clinical practice for years. The main points of the controversy are (1) the reliability of perimetric results which may be affected by compensatory eye movements and (2) heterogeneous samples consisting of patients with visual field defects and/or visuospatial neglect. By means of our newly developed and validated Virtual Reality goggles Salzburg Visual Field Trainer (SVFT) 16 stroke patients performed RT on a regular basis for 5 months. By means of our newly developed and validated Eye Tracking Based Visual Field Analysis (EFA), we conducted a first-time full eye-movement-controlled perimetric pre-post intervention study. Additionally, patients subjectively rated the size of their intact visual field. Analysis showed that patients' mean self-assessment of their subjective visual field size indicated statistically significant improvement while, in contrast, objective eye tracking controlled perimetric results revealed no statistically significant effect. Bright-light detection RT at the blind-field border solely induced a placebo effect and did not lead to training-induced neuroplasticity in the visual cortex of the type needed to ameliorate the visual field size of stroke patients.

Displaced center of pressure on the treated side in individuals with essential tremor after radiofrequency ablation: a longitudinal case-control study.

Essential tremor (ET) is a common involuntary movement disorder (IMD). Radiofrequency ablation (RFA) targeting the ventral intermediate nucleus (Vim) of the thalamus is a stereotactic neurosurgery performed in individuals with ET when pharmacotherapy is no longer effective. Though the reasons remain largely unclear, certain adverse events are known to appear post-RFA. These may be due to functional changes in the Vim, related to RFA-induced tremor reduction, or an adverse reaction to compensatory movement patterns used to perform movements in the presence of tremor symptoms. This study aimed to understand the characteristics of post-RFA symptoms in individuals with ET. In a longitudinal case-control study, we compared post-RFA symptoms between individuals with ET who underwent Vim-targeted RFA and those with IMD who underwent non-Vim-targeted RFA. Symptoms were compared preoperatively and 1-week and 1-month postoperatively. Quantitative assessments included center-of-pressure (COP) parameters, grip strength, Mini-Mental State Examination, two verbal fluency tests, and three types of physical performance assessments (upper extremity ability, balance ability, and gait ability). Individuals with ET after RFA showed horizontal displacements of the COP to the treated side (the dominant side of the RFA target's hemisphere) at 1-week postoperatively compared to the preoperative period. The horizontal COP displacement was associated with balance dysfunction related to postural stability post-RFA. Other COP parameters did not significantly differ between the ET and IMD groups. COP displacement to the treated side may be due to a time lag in adjusting postural holding strategies to the long-standing lateral difference in tremor symptoms associated with tremor improvement after RFA.

Acoustic Roughness Measurement of Railway Tracks: Running Surface Detection and Compensation of Lateral Movements for Optical Measurements on a Train.

Rolling noise is a significant contributor to railway noise. Wheel and rail roughness are decisive for the emitted noise level. An optical measurement method installed on a moving train is suitable for closer monitoring of the rail surface condition. A measurement setup based on the chord method requires the sensors to be positioned in a straight line along the direction of measurement and in a stable lateral position. Measurements should always be performed within the shiny and uncorroded running surface, even when there are lateral movements of the train. In this study, concepts for the detection of the running surface and the compensation of lateral movements are investigated in a laboratory setting. The setup consists of a vertical lathe with a ring-shaped workpiece that incorporates an implemented artificial running surface. The detection of the running surface based on laser triangulation sensors and a laser profilometer is investigated. It is shown that the running surface can be detected using a laser profilometer that measures the intensity of the reflected laser light. It is possible to detect the lateral position and the width of the running surface. A linear positioning system is proposed to adjust the lateral position of the sensors based on the running surface detection of the laser profilometer. When the lateral position of the measuring sensor is disturbed by a movement with a wavelength of 18.85 m, the linear positioning system can keep the laser triangulation sensor inside the running surface for 98.44% of the measured data points at a velocity of approximately 7.5 km h-1. The mean positioning error is 1.40 mm. By implementing the proposed system on the train, future studies can be conducted to examine the lateral position of the running surface as a function of the various operational parameters of the train.

Muscle coordination patterns in regulation of medial gastrocnemius activation during walking

The ankle plantar flexion in the late stance phase is referred to as the ankle push-off. When the ankle push-off force is enhanced, compensatory adjustments occur in the adjacent phases. The muscle control that achieves these compensatory movements remains unknown, although they are expected to be coordinately regulated across multiple muscles and phases. Muscle synergy is used as a quantification technique for muscle coordination, and this analysis enables the comparison of synchronized activity between multiple muscles. Therefore, this study aimed to elucidate the tuning of muscle synergies in muscle activation adjustment of push-off. It is hypothesized that muscle activation adjustment of push-off is performed in the muscle synergy related to ankle push-off and in the muscle synergy that activates during the adjacent push-off phase. Eleven healthy men participated, and participants manipulated the activity of the medial gastrocnemius during walking through visual feedback. Two conditions were compared as experimental conditions: increasing the muscle activity to 1.6 times that during normal walking (High) and matching it with that during normal walking (Normal). Twelve muscle activities in the trunk and lower limb and kinematic data were recorded. Muscle synergies were extracted by the non-negative matrix factorization. No significant difference was observed in the number of synergies (High: 3.5 ± 0.8, Normal: 3.7 ± 0.9, p = 0.21) and muscle synergy activation timing and duration between the High and Normal conditions (p > 0.27). However, significant differences were observed in the peak muscle activity during the late stance phase of the rectus femoris (RF), biceps femoris (BF) between conditions (RF at High: 0.32 ± 0.21, RF at Normal: 0.45 ± 0.17, p = 0.02; BF at High: 0.16 ± 0.01, BF at Normal: 0.08 ± 0.06 p = 0.02). Although the quantification of force exertion has not been conducted, the modulation of RF and BF activation could have occurred due to the attempts to help knee flexion. Muscle synergies during normal walking are therefore maintained, and slight adjustments in the amplitude of muscle activity occurred for each muscle.

Automatic Post-Stroke Severity Assessment Using Novel Unsupervised Consensus Learning for Wearable and Camera-Based Sensor Datasets

Stroke survivors often suffer from movement impairments that significantly affect their daily activities. The advancements in sensor technology and IoT have provided opportunities to automate the assessment and rehabilitation process for stroke survivors. This paper aims to provide a smart post-stroke severity assessment using AI-driven models. With the absence of labelled data and expert assessment, there is a research gap in providing virtual assessment, especially for unlabeled data. Inspired by the advances in consensus learning, in this paper, we propose a consensus clustering algorithm, PSA-NMF, that combines various clusterings into one united clustering, i.e., cluster consensus, to produce more stable and robust results compared to individual clustering. This paper is the first to investigate severity level using unsupervised learning and trunk displacement features in the frequency domain for post-stroke smart assessment. Two different methods of data collection from the U-limb datasets—the camera-based method (Vicon) and wearable sensor-based technology (Xsens)—were used. The trunk displacement method labelled each cluster based on the compensatory movements that stroke survivors employed for their daily activities. The proposed method uses the position and acceleration data in the frequency domain. Experimental results have demonstrated that the proposed clustering method that uses the post-stroke assessment approach increased the evaluation metrics such as accuracy and F-score. These findings can lead to a more effective and automated stroke rehabilitation process that is suitable for clinical settings, thus improving the quality of life for stroke survivors.

Development of a program to determine optimal settings for robot-assisted rehabilitation of the post-stroke paretic upper extremity: a simulation study

Robot-assisted therapy can effectively treat upper extremity (UE) paralysis in patients who experience a stroke. Presently, UE, as a training item, is selected according to the severity of the paralysis based on a clinician’s experience. The possibility of objectively selecting robot-assisted training items based on the severity of paralysis was simulated using the two-parameter logistic model item response theory (2PLM-IRT). Sample data were generated using the Monte Carlo method with 300 random cases. This simulation analyzed sample data (categorical data with three difficulty values of 0, 1, and 2 [0: too easy, 1: adequate, and 2: too difficult]) with 71 items per case. First, the most appropriate method was selected to ensure the local independence of the sample data necessary to use 2PLM-IRT. The method was to exclude items with low response probability (maximum response probability) within a pair in the Quality of Compensatory Movement Score (QCM) 1-point item difficulty curve, items with low item information content within a pair in the QCM 1-point item difficulty curve, and items with low item discrimination. Second, 300 cases were analyzed to determine the most appropriate model (one-parameter or two-parameter item response therapy) to be used and the most favored method to establish local independence. We also examined whether robotic training items could be selected according to the severity of paralysis based on the ability of a person (θ) in the sample data as calculated by 2PLM-IRT. Excluding items with low response probability (maximum response probability) in a pair in the categorical data 1-point item difficulty curve was effective in ensuring local independence. Additionally, to ensure local independence, the number of items should be reduced to 61 from 71, indicating that the 2PLM-IRT was an appropriate model. The ability of a person (θ) calculated by 2PLM-IRT suggested that seven training items could be estimated from 300 cases according to severity. This simulation made it possible to objectively estimate the training items according to the severity of paralysis in a sample of approximately 300 cases using this model.