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Total knee arthroplasty (TKA) is an end-stage treatment for knee osteoarthritis that relieves pain and loss of mobility, but patient satisfaction and revision rates require improvement. One cause for TKA revision is joint instability, which may be due to improper ligament balancing. A better understanding of the relationship between prosthesis design, alignment, and ligament engagement is necessary to improve component designs and surgical techniques to achieve better outcomes. We investigated the biomechanical effects of ligament model complexity and ligament wrapping during laxity tests using a virtual joint motion simulator. There was little difference in kinematics due to ligament complexity or ligament wrapping. [ABSTRACT FROM AUTHOR]

Early warning systems (EWSs) for landslides are becoming a pivotal tool to safeguard assets and stakeholders. With this mission, an EWS should be capable of reliably forecasting the failure time when the ground accelerates. There are analytical methods developed to this end that use time-series kinematics: inverse velocity (INV), minimum inverse velocity (MINV), slope gradient (SLO), and velocity over acceleration (VOA). Although an abundant number of studies applied these methods, they have been majorly examined in a back-analysis context where all the measurements are incorporated into the forecasting process. A successful operation of EWSs in raising meaningful alarms calls for an examination in which the forecasting method is evaluated synchronously. This study evaluates the ability of the four mentioned methods to provide reliable forecasts in real time using a comprehensive database including 75 historical failures. For the first time, the methods are evaluated using a quantitative metric called reliability fitness index (RFI) that measures the portion of forecasts meeting an accuracy threshold. For accuracy thresholds of 50, 75 and 90%, INV showed the highest RFI values of 16, 7, and 4% followed by SLO values of 12, 5, and 2%, respectively. Opposing reliability values for SLO and INV suggest EWSs should take advantage of hybrid models that consider both methods. [ABSTRACT FROM AUTHOR]

Many recent studies have used boil-and-bite style instrumented mouthguards to measure head kinematics during impact in sports. Instrumented mouthguards promise greater accuracy than their predecessors because of their superior ability to couple directly to the skull. These mouthguards have been validated in the lab and on the field, but little is known about the effects of decoupling during impact. Decoupling can occur for various reasons, such as poor initial fit, wear-and-tear, or excessive impact forces. To understand how decoupling influences measured kinematic error, we fit a boil-and-bite instrumented mouthguard to a 3D-printed dentition mounted to a National Operating Committee on Standards for Athletic Equipment (NOCSAE) headform. We also instrumented the headform with linear accelerometers and angular rate sensors at its center of gravity (CG). We performed a series of pendulum impact tests, varying impactor face and impact direction. We measured linear acceleration and angular velocity, and we calculated angular acceleration from the mouthguard and the headform CG. We created decoupling conditions by varying the gap between the lower jaw and the bottom face of the mouthguard. We tested three gap conditions: 0 mm (control), 1.6 mm, and 4.8 mm. Mouthguard measurements were transformed to the CG and compared to the reference measurements. We found that gap condition, impact duration, and impact direction significantly influenced mouthguard measurement error. Error was higher for larger gaps and in frontal (front and front boss) conditions. Higher errors were also found in padded conditions, but the mouthguards did not collect all rigid impacts due to inherent limitations. We present characteristic decoupling time history curves for each kinematic measurement. Exemplary frequency spectra indicating characteristic decoupling frequencies are also described. Researchers using boil-and-bite instrumented mouthguards should be aware of their limitations when interpreting results and should seek to address decoupling through advanced post-processing techniques when possible. [ABSTRACT FROM AUTHOR]

Robot technology is considered one of the most promising technologies to achieve intelligent production, with picking robots being the most common type. Picking robots are highly integrated mechatronic systems, which autonomously complete tasks including picking, carrying, and sorting. The application of picking robots enhances the efficiency of production across various environments. In this paper, a classification-design-optimization-application integrated framework of picking robots is addressed, contributing to theoretical research and application of picking robots. Classification of picking robot is established and analyzed considering the differences of overall form and end-effector to guide the development of research strategies and approaches of picking robot. Design of picking robot is described from different aspects of the target, structure, monitoring, and control design. Additionally, the commonly used optimization methods for picking robots, including structural parameters, kinematics and dynamics, and energy consumption, are discussed. Finally, the application of picking robots under different environments is expounded, and the challenges and prospects of picking robots are highlighted. This study could present theoretical support and application measures for picking robot study and technology development. [ABSTRACT FROM AUTHOR]

Generalizing smooth volumetric growth to the singular case, using de Rham currents and flat chains, we demonstrate how regular boundaries of bodies may evolve to fractals. [ABSTRACT FROM AUTHOR]

A second-order multiscale theory based on the concept of a Representative Volume Element (RVE) is proposed to link a classical poromechanical model at the RVE scale to a high-order poromechanical model at the macro-scale in the context of finite-strain kinematics. The proposed theory is carefully derived from the Principle of Multiscale Virtual Power, which is a generalization of the Hill-Mandel Principle of Macrohomogeneity. The coupled governing equations of the low-scale and the homogenization rules for the flux and stress-like quantities are obtained by means of standard variational arguments. The main theoretical result is that the minimally constrained space for the pore pressure field allows for non-zero net fluid flow across the RVE boundaries, unlike first-order theories. The direct consequence of this finding is that the present theory can be consistently applied in cases where the low-scale (RVE level) exhibits substantial volume changes (swelling or shrinking) as a consequence of the evolution of the macro-scale kinematics. Details of formulation development and expression for the homogenized tangent operators are presented for those interested in the computational implementation of the model. [ABSTRACT FROM AUTHOR]

The teleoperation of robotic manipulators allows extending the capabilities of human operators to work in different scales and distances to improve the efficiency of tasks that require high precision and repeatability. However, the lack of kinesthetics makes teleoperation difficult under diminished visibility or during palpation tasks despite visual and auditory feedback. This work presents the design and implementation of a haptic teleoperation system based on a master–slave hybrid control scheme. The robotic system uses a haptic device and a joystick to map the desired pose of the robot, while a force sensor located in the end-effector provides stiffness perception. The implemented control algorithm employs a weighted quadratic program to compute the inverse kinematics at different scales, allowing the system to operate over delicate and uneven surfaces, such as those found in surgical incisions. Finally, experimental results are shown, where the performance of the haptic system in cutting porcine tissue and manipulation tasks inside the free workspace are discussed. [ABSTRACT FROM AUTHOR]

The analysis of gait is an important tool for evaluating postoperative outcomes of a Total Knee Replacement (TKR). There are few studies which have evaluated the gait parameters of a Kinematic retaining (Kr) prosthesis. This study therefore aims to investigate the kinetic and kinematic differences of running and walking, in the ankle, knee and hip joints in patients who underwent a Kr TKR. This study assessed the gait of 12 patients with physica lima Kr TKRs at 1 year follow up and 8 healthy controls using 3D video analysis. Data was collected on the kinetics and kinematics of walking and running at the ankle, knee and hip. Comparison was made between the operated and non-operated limbs of the patients, and between the operated and control limbs. Gait analysis showed no statistically significant difference in the hip, ankle and knee angles or moments between the non-operated and operated legs during walking and running. However, there was a statistically significant difference between the knee angles of initial contact, maximum flexion during stance and swing in the TKR knees vs controls in walking and running. Similarly, there was also a statistically significantly higher max knee flexion moment between operated knees and controls in both walking and running. This study has shown that a quadriceps avoidance gait persists in patients after TKR, and that there was symmetry and reciprocated gait parameters in non-operated limbs. These findings suggest that Kr TKRs could be capable of replicating normal knee kinematics when running and walking. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of a five-week training program on undulatory underwater swimming (UUS) in swimmers and to compare the specific effects prompted by two different training protocols on UUS performance and kinematics. Swimmers (n = 14) were divided into in-water only (WO) (18.61 ± 2.62 years, FINA points: 507 ± 60) and water + dry-land training groups (with conical pulleys) (WD) (18.38 ± 2.67 years, FINA points: 508 ± 83). Three countermovement jumps (CMJ) and three maximal UUS trials were performed before and after a five-week training period. The training program comprised 14 × 30-min sessions. The WO group repeated the same 15-min block twice, while the WD group performed one block of 15 min in the water and the other block on land performing lower limb exercises with conical pulleys. Seven body landmarks were auto-digitalized during UUS by a pre-trained neural network and 21 kinematic variables were calculated. The level of statistical significance was set at p < 0.05. Significant time × group interaction in favour of the WD group was observed for mean vertical toe velocity (p = 0.035, η²p = 0.32). The WD group experienced enhancements in mean and maximum underwater velocity, kick frequency, maximum shoulder angular velocity, as well as mean and maximum vertical toe velocity (p < 0.05). The WO group exhibited an enhancement in CMJ height (p < 0.05). In conclusion, UUS performance was improved in adolescent swimmers after five weeks of specific training, only when combining water and conical pulley exercises. Coaches should include dry-land specific lower limb exercises in addition to in-water training to improve UUS performance. [ABSTRACT FROM AUTHOR]

Purpose: Most shoulder pathologies are associated with altered scapular kinematics which is mentioned as scapular dyskinesis. Scapular mobility, especially in upward rotation, measurement is essential for diagnosis and treatment. Easy-to-use, clinically applicable 2-dimensional (2-D) measurements would show excellent intra-tester reliability. To quantify intra-tester reliability for measuring scapular upward rotation in individuals with scapular dyskinesias, the landmark palpation with a video annotation tool was used. Methods: Ten participants with scapular dyskinesis were recruited. Scapular upward rotation was measured at rest, 30∘, 60∘, 90∘, and 120∘ of humeral elevation in the coronal plane both raising and lowering phases. Two trials were conducted for each arm position randomly, and an assessor took the pictures throughout. The video annotation tool (2-D Kinovia program) was used for measuring scapular upward rotation angles between days. The intra-tester reliability of scapular upward rotation was calculated. Results: This measurement technique demonstrated excellent intra-tester reliability (ICC3,1 = 0.98), range 0.96–0.99, and standard error of measurement was less than 1∘. Conclusions: The findings demonstrated that using this technique to measure scapular upward rotation was reliable in subjects with scapular dyskinesis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Kinesio taping has been widely used as a means of sports protection, but its role as a means to correct abnormal biomechanical changes of the lower limbs during side-step cutting remains unclear. OBJECTIVE: To analyze and compare the changes in lower limb kinematics and dynamics when the subjects complete the side-step cutting of the knee joint under the conditions of kinesio taping, placebo taping and blank control. METHODS: Thirty-nine male college students majoring in basketball were recruited as subjects. Each subject was tested with kinesio taping, placebo taping or no taping. The mechanical correction method was used to patch the dominant knee joint of each subject. The run-up speed of 4.5-5.5 m/s was selected to complete the 45° side-step cutting motion, and the kinematics and kinetics data were collected synchronously by the three-dimensional dynamic capture system and the force measuring platform. The kinematics and kinetics parameters at the moment of initial touchdown and peak ground reaction force were selected for data analysis. SPSS 27.0 software was used for statistical analysis of the test data. RESULTS AND CONCLUSION: Kinematic indexes: compared with no taping and placebo taping, the hip abduction and knee valgus angles at the initial touchdown moment were significantly decreased when kinesio taping was used (P < 0.05); at the moment of peak lateral ground reaction force, the angles of hip abduction, knee valgus and ankle plantar flexion decreased significantly (P < 0.05), and the knee flexion angle was significantly increased (P < 0.05). Kinetic indexes: Compared with no taping, both kinesio taping and placebo taping significantly reduced hip abduction and external rotation torque, knee valgus and external rotation torque at the moment of initial touchdown (P < 0.05), and significantly reduced peak vertical ground reaction force and peak horizontal backward ground reaction force (P < 0.05); in addition, kinesio taping significantly reduced peak lateral ground reaction force compared with no taping and placebo taping (P < 0.05). These results indicate that kinesio taping of the knee joint may improve some kinematic and kinetic indexes associated with lower limb injury risk factors during the completion of the side-step cutting in basketball specialized college students to some extent, and may have a positive effect on the prevention of injury during the side-step cutting. In addition, the trends in the effects of placebo taping and kinesio taping on the knee joint are more consistent in terms of changes in some indexes, suggesting that there may be a placebo effect on the mechanism of action of kinesio taping. [ABSTRACT FROM AUTHOR]

Quantitative three-dimensional gait analysis has been used to evaluate the loading at the knee (i.e. external knee adduction moment, EKAM) during level ground walking in individuals with knee osteoarthritis (OA). The magnitude of EKAM can be influenced by some factors, such as knee marker position and foot placement angles in static calibration trials, which may lead to inaccurate functional assessments and intervention planning. This study aimed to clarify the effects of knee position during static calibration trials on the evaluation of knee loading during gait in individuals with medial knee OA. Seventeen individuals with medial knee OA completed three different static standing trials; (1) knee flexed at 0 degrees, (2) knee flexed at 15 degrees, and (3) knee flexed at 30 degrees before walking at their self-selected speed. A sixteen-camera three-dimensional VICON gait analysis system with four AMTI force platforms was used to collect the EKAM, knee adduction angular impulse (KAAI), knee joint center (KJC), and other knee kinematic and kinetic variables during gait. A repeated measures ANOVA was used to investigate the differences between conditions. The 1st peak of EKAM, the 1st peak EKAM arm, KAAI, and knee extension moment were significantly increased at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P < 0.05). Additionally, the knee flexion moment and knee external rotation moment were significantly reduced at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P < 0.05). All biomechanical variables were influenced by the localization of the KJC during static calibration trials. The changes in knee position during static trials significantly affected the 1st peak EKAM, KAAI, and other knee kinematics and kinetics variables during gait. Therefore, future studies should consider keeping the participants’ knees in a consistent position during static trials between visits, as the variations in knee position could mask or exaggerate the differences between groups and interventions. [ABSTRACT FROM AUTHOR]

Introduction: Stiffness (k) describes a material’s resistance to deformation and is useful for understanding neuromuscular function, performance, and injury risk. The aim of this study is to compare the lower limb stiffness method (kLLS), which uses only force plate data, with methods combining force plate and motion capture data to calculate stiffness during the eccentric phase of a countermovement. Material and Methods: Twelve resistance-trained males: age 24.9 (4.4) years, height 1.81 (0.05) m, weight 88.2 (14) kg) performed three maximal effort countermovement jumps (CMJ). Data were collected synchronously using three-dimensional (3D) kinematic and kinetic data (dual force plate setup). Lower limb stiffness (z), joint stiffness (x, y, and z), and leg stiffness (linear, sagittal plane, and 3D) were calculated for the eccentric phase of all CMs. Results: kLLS showed high concurrent validity with strong correlations to kinetic-kinematic methods (r = 0.90-0.97, p < 0.05). A linear mixed model revealed no significant differences in k-values between kLLS and leg stiffness, indicating high concurrent validity. Discussion: kLLS offers valid and valuable information affecting performance, injury risk, and return-to-sport decisions. Conclusion: The findings suggest that kLLS is a valid method for calculating stiffness in CMJs and equal to 3D leg stiffness. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the variation of individual and group competitive learning strategies on technique, kinematic variables in the front crawl stroke swimming, and intelligent physical-motor among swimming level 2 course students. The sample of the study consisted of 16 students, it was selected based on Intentional style of swimming level 2 course students involved in the second semester (2018/2019) who divided into two similar groups; A: control group (8) students learning with the traditional style, B: experimental group (8) students learning with competitive strategy. The following variables have been measured: skill level, frequency and stroke length, and speed of swimming 50m at front crawl stroke as well as intelligent physical-motor. The results of the study showed that the traditional learning method has a positive impact on improving skillfulness and speed of swimming 50 m at front crawl stroke performance. On the other hand, a competitive learning strategy has a significant effect in improving the performance of swimming 50m at front crawl stroke between students. The researcher recommends using a competitive learning strategy better when implementing swimming education programs to enhance technique skills and mechanical performance in front crawl stroke swimming and evaluate the level of intelligent physical-motor to know the right and viable strategy that would be used in swimming learning and use the results of kinetic analysis when evaluating students swimming to give feedback to detect weaknesses in performance to modify them. [ABSTRACT FROM AUTHOR]

The circumgalactic medium (CGM) hosts many physical processes with different kinematic signatures that affect galaxy evolution. We address the CGM–galaxy kinematic connection by quantifying the fraction of H  i that is aligned with galaxy rotation with the equivalent width co-rotation fraction, |$f_{\rm EWcorot}$|⁠. Using 70 quasar sightlines having Hubble Space Telescope /Cosmic Origins Spectrograph H  i absorption (⁠|${12\lt \log (N(\rm{{\rm H}\,{\small I}})/{\rm cm}^{-2})\lt 20}$|⁠) within |$5R_{\rm vir}$| of |$z\lt 0.6$| galaxies we find that |$f_{\rm EWcorot}$| increases with increasing H  i column density. |$f_{\rm EWcorot}$| is flat at |$\sim 0.6$| within |$R_{\rm vir}$| and decreases beyond |$R_{\rm vir}$| to |$f_{\rm EWcorot}$| |$\sim 0.35$|⁠. |$f_{\rm EWcorot}$| also has a flat distribution with azimuthal and inclination angles within |$R_{\rm vir}$|⁠ , but decreases by a factor of two outside of |$R_{\rm vir}$| for minor axis gas and by a factor of 2 for edge-on galaxies. Inside |$R_{\rm vir}$|⁠ , co-rotation dominated H i is located within |$\sim 20$| deg of the major and minor axes. We surprisingly find equal amounts of H  i absorption consistent with co-rotation along both major and minor axes within |$R_{\rm vir}$|⁠. However, this co-rotation disappears along the minor axis beyond |$R_{\rm vir}$|⁠ , suggesting that if this gas is from outflows, then it is bound to galaxies. |$f_{\rm EWcorot}$| is constant over two decades of halo mass, with no decrease for log(M |$_{\rm h}/{\rm M}_{\odot })\gt 12$| as expected from simulations. Our results suggest that co-rotating gas flows are best found by searching for higher column density gas within |$R_{\rm vir}$| and near the major and minor axes. [ABSTRACT FROM AUTHOR]

This study compared lower extremity, trunk, and upper extremity kinematics between tee and front toss hitting in youth baseball athletes. Twenty youth baseball athletes (14.3±2.9 yrs) performed three maximal effort swings off front toss and tee. Kinematic data were collected during the preparatory and acceleration phases. Lower extremity, trunk, and upper extremity kinematics were compared between tee and front toss hitting using 1-dimensional statistical parametric mapping (SPM). There was a significant difference in trunk kinematics between tee and front toss during the preparatory phase (p=.001); the trunk rotated more toward the back side when hitting off a tee compared to front toss (p<0.001). There was also a significant difference in trunk kinematics between tee and front toss for 67% of the acceleration phase; the trunk rotated more towards the back side from 0 to 67% when hitting off the tee (p<0.001). Significant differences were found in trunk kinematics between tee and front toss hitting in youth baseball players, where the trunk is less rotated toward the pitcher in the tee than in the front toss. Coaches utilize various training modalities to enhance hitting performance; however, differences in trunk kinematics should be considered between modalities when developing fundamental hitting techiques in youth baseball athletes. [ABSTRACT FROM AUTHOR]

Kinematic principle in lapping process is an essential theoretical foundation to achieve high lapping accuracy. The motion path of abrasive grains determines the machined area on workpiece, thereby affecting the surface accuracy. To improve lapping uniformity, this paper established a kinematic model of swing fixed-abrasive lapping (SFAL) and investigated the effect of kinematic parameters (rotational speed ratio, swing ratio, swing angle) on lapping uniformity. Non-uniformity coefficient (NUC) was adopted to evaluate the lapping uniformity, and the impact mechanism of kinematic parameters on the trajectory of abrasive grains were revealed by Taguchi experiments and numerical simulation. Furthermore, response surface experiments were employed to optimize the parameter combination, and a prediction model for NUC was developed. This work provides theoretical guidance for the selection of kinematic parameters in SFAL process, and has reference significance for improving the lapping accuracy. [ABSTRACT FROM AUTHOR]

AbstractMany researchers are interested in how the kinematics of reach-to-grasp movements in virtual reality (VR), which involve the vergence–accommodation conflict, differ from real space. The present study, conducted in VR, verified the effect of a discrepancy between visual and haptic target size and found that terminal haptic feedback is weighted more heavily than visual information, as is the case in real space. Furthermore, we investigated how the presence or absence of terminal haptic feedback modulates performance in VR by comparing prehension with or without terminal haptic feedback in VR, closed-loop natural grasping in real space, and pantomimed prehension with the eyes closed. Our results suggested that the contribution of a visual image to grip aperture adjustment is quite marginal in situations where terminal haptic feedback is unavailable, and that the performance in VR without haptic feedback is highly correlated with performances driven by fully internal representations (i.e., pantomimed movements). [ABSTRACT FROM AUTHOR]

The purpose of this quasiexperimental study was to test the effects of wearing the NewGait rehabilitative device on walking abilities in individuals with foot drop. The study involved 16 participants with foot drops caused by stroke (11 participants), multiple sclerosis (one participant), and peripheral neuropathies (four individuals). During a single testing session, participants walked 12 m at their self‐selected speed in four experimental conditions: walking without any orthotic device; walking while wearing a regular plastic posterior leaf ankle foot orthosis (AFO); walking with the NewGait device assisting ankle dorsiflexion only; and walking with the NewGait device assisting the hip, knee, and ankle joint motions. Body motions during walking were recorded using a 3D system for motion analysis and analyzed with a set of spatiotemporal and kinematic parameters and a gait decomposition index. The gait decomposition index indicated sagittal interjoint coordination in the three joint pairs (hip–knee, knee–ankle, and hip–ankle) of the paretic (foot drop) leg during walking and was validated in a previous study. Overall, wearing all three orthotic devices improved the gait velocity, ankle dorsiflexion, and foot clearance compared to gait trials in which no assistive devices were used. However, wearing the AFO significantly restricted the plantarflexion range of motion and decreased interjoint coordination as measured by joint decomposition. In contrast, the NewGait device altered the ankle plantarflexion motions but also increased coordinated movement (reduced the decomposition) in most lower‐extremity joint pairs and conditions. Therefore, the NewGait rehabilitative device can be considered superior to a regular AFO in correcting gait deviations caused by foot drop. [ABSTRACT FROM AUTHOR]

This paper introduces the flexible control and trajectory planning medical two-arm surgical robots, and employs effective collision detection methods to ensure the safety and precision during tasks. Firstly, the DH method is employed to establish relative rotation matrices between coordinate systems, determining the relative relationships of each joint link. A neural network based on a multilayer perceptron is proposed to solve FKP problem in real time. Secondly, a universal interpolator based on Non-Uniform Rational B-Splines (NURBS) is developed, capable of handling any geometric shape to ensure smooth and flexible motion trajectories. Finally, we developed a generalized momentum observer to detect external collisions, eliminating the need for external sensors and thereby reducing mechanical complexity and cost. The experiments verify the effectiveness of the kinematics solution and trajectory planning, demonstrating that the improved momentum torque observer can significantly reduce system overshoot, enabling the two-arm surgical robot to perform precise and safe surgical tasks under algorithmic guidance. [ABSTRACT FROM AUTHOR]

Studies reported the existence of instability catch (IC) during trunk flexion in patients with chronic low back pain (CLBP). However, different movement speeds can cause different neuromuscular demands resulting in altered kinematic patterns. In addition, kinematic characterization corresponding to clinical observation of IC is still limited. Therefore, this study aimed to determine (1) the association between movement speed and kinematic parameters representing IC during trunk flexion and (2) the differences in kinematic parameters between individuals with and without CLBP. Fifteen no low back pain (NoLBP) and 15 CLBP individuals were recruited. Inertial measurement units (IMU) were attached to T3, L1, and S2 spinous processes. Participants performed active trunk flexion while IMU data were simultaneously collected. Total trunk, lumbar, and pelvic mean angular velocity (T_MV, L_MV, and P_MV), as well as number of zero-crossings, peak-to-peak, and area of sudden deceleration and acceleration (Num, P2P, and Area), were derived. Pearson's correlation tests were used to determine the association between T_MV and L_MV, P_MV, Num, P2P, and Area. An ANCOVA was performed to determine the difference in kinematic parameters between groups using movement speed as a covariate. Significant associations (P < 0.05) were found between movement speed and other kinematic parameters, except for Area. Results showed that L_MV significantly differed from the P_MV (P = 0.002) in the CLBP group, while a significant between-group difference (P = 0.037) was found in the P_MV. Additionally, significant between-group differences (P < 0.05) in P2P and Area were observed. The associations between movement speed and kinematic parameters suggest that movement speed changes can alter kinematic patterns. Therefore, clinicians may challenge lumbopelvic neuromuscular control by modifying movement speed to elicit greater change in kinematic patterns. In addition, the NoLBP group used shared lumbar and pelvic contributions, while the CLBP group used less pelvic contribution. Finally, P2P and Area appeared to offer the greatest sensitivity to differentiate between the groups. Overall, these findings may enhance the understanding of the mechanism underlying IC in CLBP. [ABSTRACT FROM AUTHOR]

Background: To overcome the application limitations of functional electrical stimulation (FES), such as fatigue or nonlinear muscle response, the combination of neuroprosthetic systems with robotic devices has been evaluated, resulting in hybrid systems that have promising potential. However, current technology shows a lack of flexibility to adapt to the needs of any application, context or individual. The main objective of this study is the development of a new modular neuroprosthetic system suitable for hybrid FES-robot applications to meet these needs. Methods: In this study, we conducted an analysis of the requirements for developing hybrid FES-robot systems and reviewed existing literature on similar systems. Building upon these insights, we developed a novel modular neuroprosthetic system tailored for hybrid applications. The system was specifically adapted for gait assistance, and a technological personalization process based on clinical criteria was devised. This process was used to generate different system configurations adjusted to four individuals with spinal cord injury or stroke. The effect of each system configuration on gait kinematic metrics was analyzed by using repeated measures ANOVA or Friedman’s test. Results: A modular NP system has been developed that is distinguished by its flexibility, scalability and personalization capabilities. With excellent connection characteristics, it can be effectively integrated with robotic devices. Its 3D design facilitates fitting both as a stand-alone system and in combination with other robotic devices. In addition, it meets rigorous requirements for safe use by incorporating appropriate safety protocols, and features appropriate battery autonomy, weight and dimensions. Different technological configurations adapted to the needs of each patient were obtained, which demonstrated an impact on the kinematic gait pattern comparable to that of other devices reported in the literature. Conclusions: The system met the identified technical requirements, showcasing advancements compared to systems reported in the literature. In addition, it demonstrated its versatility and capacity to be combined with robotic devices forming hybrids, adapting well to the gait application. Moreover, the personalization procedure proved to be useful in obtaining various system configurations tailored to the diverse needs of individuals. [ABSTRACT FROM AUTHOR]

Background: Motor difficulties are common in many, but not all, autistic individuals. These difficulties can co-occur with other problems, such as delays in language, intellectual, and adaptive functioning. Biological mechanisms underpinning such difficulties are less well understood. Poor motor skills tend to be more common in individuals carrying highly penetrant rare genetic mutations. Such mechanisms may have downstream consequences of altering neurophysiological excitation-inhibition balance and lead to enhanced behavioral motor noise. Methods: This study combined publicly available and in-house datasets of autistic (n = 156), typically-developing (TD, n = 149), and developmental coordination disorder (DCD, n = 23) children (age 3–16 years). Autism motor subtypes were identified based on patterns of motor abilities measured from the Movement Assessment Battery for Children 2nd edition. Stability-based relative clustering validation was used to identify autism motor subtypes and evaluate generalization accuracy in held-out data. Autism motor subtypes were tested for differences in motor noise, operationalized as the degree of dissimilarity between repeated motor kinematic trajectories recorded during a simple reach-to-drop task. Results: Relatively 'high' (n = 87) versus 'low' (n = 69) autism motor subtypes could be detected and which generalize with 89% accuracy in held-out data. The relatively 'low' subtype was lower in general intellectual ability and older at age of independent walking, but did not differ in age at first words or autistic traits or symptomatology. Motor noise was considerably higher in the 'low' subtype compared to 'high' (Cohen's d = 0.77) or TD children (Cohen's d = 0.85), but similar between autism 'high' and TD children (Cohen's d = 0.08). Enhanced motor noise in the 'low' subtype was also most pronounced during the feedforward phase of reaching actions. Limitations: The sample size of this work is limited. Future work in larger samples along with independent replication is important. Motor noise was measured only on one specific motor task. Thus, a more comprehensive assessment of motor noise on many other motor tasks is needed. Conclusions: Autism can be split into at least two discrete motor subtypes that are characterized by differing levels of motor noise. This suggests that autism motor subtypes may be underpinned by different biological mechanisms. [ABSTRACT FROM AUTHOR]

Objective: To investigate in vivo 6-degree-of-freedom (DOF) vertebral motion in patients with isthmic spondylolisthesis (IS) during various functional weight-bearing activities. Methods: Fifteen asymptomatic volunteers (mean age 54.8 years) and fourteen patients with IS at L4-5 (mean age 53.4 years) were recruited. The positions of the vertebrae (L4-L5) in the supine, standing, flexion–extension, left–right twisting and left–right bending positions were determined using previously described CT-based models and dual fluoroscopic imaging techniques. Local coordinate systems were established at the center of the anterior vertebra of L4 isthmic spondylolisthesis (AIS), the posterior lamina of L4 isthmic spondylolisthesis (PIS) and the center of the L5 vertebra to obtain the 6DOF range of motion (ROM) at L4-L5 and the range of motion (ROM) between the AIS and the PIS. Results: The translation along the anteroposterior axis at L4-L5 during flexion–extension, left–right bending and left–right twisting was significantly greater than that of the healthy participants. However, the translation along the mediolateral axis at L4-L5 presented paradoxical motion under different positions: the ROM increased in the supine-standing and flexion–extension positions but decreased in the left–right bending and left–right twisting positions. The separation along the anteroposterior axis during flexion was significantly greater than that during standing, on average, reaching more than 1 mm. The separation along the mediolateral axis during standing, flexion and extension was significantly greater than that in the supine position. Conclusions: This study revealed the occurrence of displacement between the AIS and PIS, primarily in the form of separation during flexion. Symptomatic patients with isthmic spondylolisthesis exhibit intervertebral instability, which might be underestimated by flexion–extension radiographs. [ABSTRACT FROM AUTHOR]

Stiff knee gait (SKG) occurrence after a stroke is associated with various abnormal muscle activities; however, the interactions among these muscles are unclear. This study aimed to elucidate the muscle synergy characteristics during walking in patients with SKG after a stroke. This cross-sectional study included 20 patients with poststroke SKG (SKG group), 16 patients without poststroke SKG (non-SKG group), and 15 healthy adults (control group). Participants walked a 10-m distance at a comfortable speed, and electromyographic data were recorded from six lower-limb muscles. Non-negative matrix factorization was employed to derive time-varying activity (C), muscle weights (W), and the percentage of total variance accounted for (tVAF) for muscle synergies. The SKG group showed a higher tVAF than the control group. The initial stance module (including knee extensors) showed increased activity during the swing phase. The initial swing module (including hip flexors and ankle dorsiflexors) exhibited a higher activity during the single-support phase but a lower activity during the swing phase. The synergy structure in patients with SKG after stroke was simplified, with specific abnormalities in synergy activities. SKG may arise from several synergy alterations involving multiple muscles, indicating that approaches focused on controlling individual muscle activities are unsuitable. [ABSTRACT FROM AUTHOR]

Information about another person's movement kinematics obtained through visual observation activates brain regions involved in motor learning. Observation-related changes in these brain areas are associated with adaptive changes to feedforward neural control of muscle activation and behavioral improvements in limb movement control. However, little is known about the stability of these observation-related effects over time. Here, we used force channel trials to probe changes in lateral force production at various time points (1 min, 10 min, 30 min, 60 min, 24 h) after participants either physically performed, or observed another individual performing upper limb reaching movements that were perturbed by novel, robot-generated forces (a velocity-dependent force-field). Observers learned to predictively generate directionally and temporally specific compensatory forces during reaching, consistent with the idea that they acquired an internal representation of the novel dynamics. Participants who physically practiced in the force-field showed adaptation that was detectable at all time points, with some decay detected after 24 h. Observation-related adaptation was less temporally stable in comparison, decaying slightly after 1 h and undetectable at 24 h. Observation induced less adaptation overall than physical practice, which could explain differences in temporal stability. Visually acquired representations of movement dynamics are retained and continue to influence behavior for at least 1 h after observation. NEW & NOTEWORTHY: We used force channel probes in an upper limb force-field reaching task in humans to compare the durability of learning-related changes that occurred through visual observation to those after physical movement practice. Visually acquired representations of movement dynamics continued to influence behavior for at least 1 h after observation. Our findings point to a 1-h window during which visual observation of another person could play a role in motor learning. [ABSTRACT FROM AUTHOR]

Bradykinesia is a term describing several manifestations of movement disruption caused by Parkinson's disease (PD), including movement slowing, amplitude reduction, and gradual decrease of speed and amplitude over multiple repetitions of the same movement. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves bradykinesia in patients with PD. We examined the effect of DBS on specific components of bradykinesia when applied at two locations within the STN, using signal processing techniques to identify the time course of amplitude and frequency of repeated hand pronation-supination movements performed by participants with and without PD. Stimulation at either location increased movement amplitude, increased frequency, and decreased variability, though not to the range observed in the control group. Amplitude and frequency showed decrement within trials, which was similar in PD and control groups and did not change with DBS. Decrement across trials, by contrast, differed between PD and control groups, and was reduced by stimulation. We conclude that DBS improves specific aspects of movement that are disrupted by PD, whereas it does not affect short-term decrement that could reflect muscular fatigue. NEW & NOTEWORTHY: In this study, we examined different components of bradykinesia in patients with Parkinson's disease (PD). We identified different components through signal processing techniques and their response to deep brain stimulation (DBS). We found that some components of bradykinesia respond to stimulation, whereas others do not. This knowledge advances our understanding of brain mechanisms that control movement speed and amplitude. [ABSTRACT FROM AUTHOR]

Hamstring strain injuries (HSIs) are prevalent in sports involving high-speed running and most of the HSIs are biceps femoris long head (BFlh) injuries. The primary cause for HSIs during high-speed running remains controversial due to the lack of in vivo measurement of the BFlh muscle behavior during running. Therefore, the purpose of this study was to quantify the muscle-tendon unit (MTU) and fascicle behavior of BFlh during running. Seven college male sprinters (22.14 ± 1.8 years; 177.7 ± 2.5 cm; 70.57 ± 5.1 kg; personal bests in 100m: 11.1 ± 0.2 s) were tested on a motorized treadmill instrumented with two force plate for running at 4, 5, 6m/s. The ground reaction force (GRF), 3D lower limb kinematics, EMG, and ultrasound images of biceps femoris long head (BFlh) in the middle region were recorded simultaneously. BFlh fascicles undergo little length change (about 1 cm) in the late swing phase during running at three submaximal speeds. BFlh fascicle lengthening accounted for about 30% of MTU length change during the late swing phase. BFlh was most active during the late swing and early stance phases, ranging from 83% MVC at a running speed of 4 m/s to 116% MVC at 6 m/s. Muscle fascicles in the middle region of BF1h undergo relatively little lengthening relative to the MTU in the late swing phase during running in comparison to results from simulation studies. These results suggest that there is a decoupling between the fascicle in the middle region and MTU length changes during the late swing phase of running. [ABSTRACT FROM AUTHOR]

This study examined the relationship between motor competence (MC) and Landing Error Scoring System (LESS) performance in a sample of male junior grassroots footballers aged 10-13 years. Ninety-eight boys aged 10-13 years (mean ± SD = 11.7 ± 1 years) undertook assessment of MC, using the Test of Gross Motor Development (third edition) and anterior cruciate ligament (ACL) injury risk using the LESS. Height and mass were assessed from which maturity status was predicted. Multiple backward linear regressions indicated a significant model (p = 0.001), which explained 49% of the variance in LESS scores. Locomotor MC (β = -0.538, p = 0.001), object control MC (β = -0.261, p = 0.004), and age (β = 1.17, p = 0.03) significantly contributed to the model. Maturity offset (p = 0.100) was not significant. Analysis of covariance (controlling for age and maturity offset) indicated a significant difference in locomotor MC between those classified as poor for LESS. A similar result was observed for object control MC (p = 0.003, ηp² = 0.09), where those classed as poor for LESS had significantly poorer object control MC compared with those classed as excellent, good, and moderate. The results of this study indicate that there is a relationship between both locomotor and object control MC and errors in drop jump landing mechanics in boys aged 10-13 years, with MC explaining nearly 50% of the variance in LESS scores. Practically, this study indicates that MC, particularly locomotor MC, has potential to identify performance in jump landing tests that are associated with increased risk of ACL injury in boys who play grassroots soccer. [ABSTRACT FROM AUTHOR]

High-quality cutting technique is essential for agility development and safer cuttings in adolescent athletes. Certain sidestep techniques and kinematics are characteristic of high movement quality and are associated with both, faster performance and lower knee joint loading (i.e., reduced anterior cruciate ligament injury risk). The aim of this study was to determine the effects of a 6-week, side step, technique modification training intervention targeting specific kinematics on agility performance and movement quality. Twenty-two adolescent American football players were recruited for a nonrandomized, controlled, intervention study. For 6 weeks, an intervention group (IG) of 11 players participated in 25-minute cutting technique training sessions integrated into team training twice a week, whereas a control group (CG) of 11 players continued their usual training routine. Agility performance was assessed based on percentage-based change of direction deficit (CODDp) obtained during reactive agility tests at 45° and 90° angles. The Cutting Movement Assessment Score (CMAS) qualitative screening tool was used to assess 2D high-speed videos of the cuts for movement quality. The significance level was set at α = 0.01. The intervention effectively altered players' sidestep technique irrespective of cutting angle with large time x group interaction effects observed for CMAS (ηp² = 0.82). Statistical and practical significant improvements in CMAS pre-to-post intervention were evident in the IG (-2.30 ≤ g ≤ -1.75; 313.87 ≤ BF10 ≤ 2,342.00), whereas deteriorations were found in the CG for 90° (g = 1.38; BF10 = 64.21). However, in both groups, no statistically significant differences in CODDp were observed pre-to-post intervention (0.019 ≤ p ≤ 0.586; 0.34 ≤ BF10 ≤ 3.59). The cutting technique modification training meaningfully improved movement quality, without negatively affecting agility performance, and can be used by practitioners to foster a safe technical foundation for subsequent agility development in adolescent athletes. [ABSTRACT FROM AUTHOR]

Sea ice models are essential tools for simulating the thermodynamic and dynamic processes of sea ice and the coupling with the polar atmosphere and ocean. Popular models such as the Community Ice CodE (CICE) are usually based on non-moving, locally orthogonal Eulerian grids. However, the various in situ observations, such as those from ice-tethered buoys and drift stations, are subjected to sea ice drift and are, hence, by nature Lagrangian. Furthermore, the statistical analysis of sea ice kinematics requires the Lagrangian perspective. As a result, the offline sea ice tracking with model output is usually carried out for many scientific and validational practices. Certain limitations exist, such as the need for high-frequency model outputs, as well as unaccountable tracking errors. In order to facilitate Lagrangian diagnostics in current sea ice models, we design and implement an online Lagrangian tracking module in CICE under the coupled model system of CESM (Community Earth System Model). In this work, we introduce its design and implementation in detail, as well as the numerical experiments for the validation and the analysis of sea ice deformation. In particular, the sea ice model is forced with historical atmospheric reanalysis data, and the Lagrangian tracking results are compared with the observed buoys' tracks for the years from 1979 to 2001. Moreover, high-resolution simulations are carried out with the Lagrangian tracking to study the multi-scale sea ice deformation modeled by CICE. Through scaling analysis, we show that CICE simulates multi-fractal sea ice deformation fields in both the spatial and the temporal domain, as well as the spatial–temporal coupling characteristics. The analysis with model output on the Eulerian grid shows systematic difference with the Lagrangian-tracking-based results, highlighting the importance of the Lagrangian perspective for scaling analysis. Related topics, including the sub-daily sea ice kinematics and the potential application of the Lagrangian tracking module, are also discussed. [ABSTRACT FROM AUTHOR]

Background/Objectives: There is emerging evidence that task-specific pain-related psychological measures may better predict movement behaviour in chronic low back pain (CLBP) than general pain-related psychological measures. Currently, little is known regarding the prediction of movement duration and movement velocity. Methods: Baseline data from a previously published randomized controlled trial were used (clinicaltrials.gov NCT02773160). Fifty-five patients with CLBP and 54 pain-free persons performed a lifting task while kinematic measurements were obtained to calculate movement velocity of the L1 vertebra, S1 vertebra, and the lumbar spine, as well as the time to complete the lifting task. Scores on the Photograph Daily Activities Series-Short Electronic Version (PHODA-SeV), Tampa Scale for Kinesiophobia (TSK), and its Activity Avoidance and Somatic Focus subscales were used as general pain-related psychological measures. The score on a picture of the PHODA-SeV, showing a person lifting an object with a bent back (PHODA-Lift), was used as task-specific measure of perceived harmfulness. Results: The task-specific measure best predicted movement duration and movement velocity of L1 and the lumbar spine, and explained 35%, 19%, and 25% of the respective movement parameters. Although general perceived harmfulness predicted S1 velocity and movement duration, it only explained 6% and 8% of the respective movement parameters. General measures of pain-related fear were not predictive for any of the movement parameters. It took patients with CLBP significantly longer to complete the lifting task when compared to the pain-free participants (ES = 1.01, p < 0.0001), and patients with CLBP also moved significantly slower at L1 (ES = 0.85, p < 0.0001) and the lumbar spine (ES = 1.01, p < 0.0001). These between-groups differences were larger for CLBP subgroups with higher scores on the PHODA-Lift, and to some extent for subgroups with higher total scores on the PHODA-SeV. Conclusions: Task-specific perceived harmfulness best predicts movement velocity. General pain-related fear measures (i.e., TSK and its subscales) do not predict these movement parameters. [ABSTRACT FROM AUTHOR]

We aimed to conduct a biophysical comparison of angular (Biorower) and linear (Concept2) rowing ergometers across a wide spectrum of exercise intensities. Sixteen (eleven male) skilled rowers, aged 29.8 ± 8.6 and 23.6 ± 1.5 years, with international competitive experience, performed 7 × 3 min bouts with 30 W increments and 60 s intervals, plus 1 min of all-out rowing on both machines with 48 h in between. The ventilatory and kinematical variables were measured breath-by-breath using a telemetric portable gas analyzer and determined using a full-body markerless system, respectively. Similar values of oxygen uptake were observed between ergometers across all intensity domains (e.g., 60.36 ± 8.40 vs. 58.14 ± 7.55 mL/min/kg for the Biorower and Concept2 at severe intensity). The rowing rate was higher on the Biorower vs. Concept2 at heavy and severe intensities (27.88 ± 3.22 vs. 25.69 ± 1.99 and 30.63 ± 3.18 vs. 28.94 ± 2.29). Other differences in kinematics were observed across all intensity domains, particularly in the thorax angle at the finish (e.g., 19.44 ± 4.49 vs. 27.51 ± 7.59° for the Biorower compared to Concep2 at heavy intensity), likely due to closer alignment of the Biorower with an on-water rowing technique. The overall perceived effort was lower on the Biorower when compared to the Concept2 (14.38 ± 1.76 vs. 15.88 ± 1.88). Rowers presented similar cardiorespiratory function on both rowing ergometers, while important biomechanical differences were observed, possibly due to the Biorower's closer alignment with an on-water rowing technique. [ABSTRACT FROM AUTHOR]

A common challenge for exoskeleton control is discerning operator intent to provide seamless actuation of the device with the operator. One way to accomplish this is with joint angle estimation algorithms and multiple sensors on the human–machine system. However, the question remains of what can be accomplished with just one sensor. The objective of this study was to deploy a modular testing approach to test the performance of two joint angle estimation models—a kinematic extrapolation algorithm and a Random Forest machine learning algorithm—when each was informed solely with kinematic gait data from a single potentiometer on an ankle exoskeleton mock-up. This study demonstrates (i) the feasibility of implementing a modular approach to exoskeleton mock-up evaluation to promote continuity between testing configurations and (ii) that a Random Forest algorithm yielded lower realized errors of estimated joint angles and a decreased actuation time than the kinematic model when deployed on the physical device. [ABSTRACT FROM AUTHOR]

Accurate sensing and control are important for high-performance formation control of spacecraft systems. This paper presents a strategy of disturbance estimation and distributed predefined-time control for the formation of multi-spacecraft systems with uncertainties based on a disturbance observer. The process begins by formulating a kinematics model for the relative motion of spacecraft, with the formation's communication topology represented by a directed graph for the formation system of the spacecraft. A disturbance observer is then developed to estimate the disturbances, and the estimation errors can be convergent in fixed time. Following this, a disturbance-estimation-based sliding mode control is proposed to guarantee the predefined-time convergence of the multi-spacecraft formation system, regardless of initial conditions. It allows each spacecraft to reach its desired position within a set time frame. The results of the analysis of the multi-spacecraft formation system are also provided. Finally, an example simulation of a five-spacecraft formation flying system is provided to demonstrate the presented formation control method. [ABSTRACT FROM AUTHOR]

Standing long jump is known as one of the important skills in the success of athletes in most sports. In addition, one of the most effective factors that can affect standing long jump distance and kinematics is the focus of attention used by the athlete. Therefore, the aim of the present study was to compare the effect of internal, external, and holistic focus of attention instructions on standing long jump performance and kinematics. The participants were 30 novices (all males; mean age = 21.70 ± 2.21 years; mean height = 175.73 ± 6.09 cm; and mean weight = 73.76 ± 11.77 kg) who performed 12 standing long jumps in four focus of attention conditions. Internal focus, external focus, holistic focus, and control conditions were implemented in a counterbalanced order. Jump distance and maximum knee flexion angle before take-off were recorded in all trials. The results showed that in relation to the standing long jump performance, the distance was similar in external and holistic focus conditions, and both were superior to internal or control conditions. There was no difference between control and internal focus of attention conditions. The results related to movement kinematics, however, did not report a difference between the maximum flexion angles before take-off. This study replicates the benefits of external and holistic focus instructions for jump distance, but this difference was not a product of different maximum knee flexion angles. It is suggested that coaches implement external and/or holistic focus cues to maximize athlete performance in jumping tasks. [ABSTRACT FROM AUTHOR]

Background: Although the Lee Silverman Voice Treatment BIG® (LSVT BIG®) improves motor symptoms in patients with Parkinson's Disease, no reports exist for patients with Progressive Supranuclear Palsy (PSP). Objective: To describe the effect of LSVT BIG® on the motor symptoms of a participant with PSP. Case Description: The participant was a 74-year-old man with PSP. His goals were to improve limb movement, balance ability, and festinating gait over the 4-week LSVT BIG® program. Outcomes: All assessments of limb movement and balance ability showed improvements after intervention for the limb and gait subsections of the PSP rating scale. Scores improved from 9 to 5, and 8 to 6, respectively for the Unified Parkinson's Disease Rating Scale (UPDRS) Part 3, from 30 to 21 and for the Berg balance scale (BBS), from 45 to 50 points. The improvements in UPDRS Part 3 and BBS exceeded the minimum detectable change values (7–8 and 2 points, respectively). After intervention, improvements in festinating gait and rapid walking pace were noted on the UPDRS Part 3 (2 to 1 point) and 10-meter walk test (1.65 m/s to 1.10 m/s). Conclusion: The intervention was effective for the participant but further studies with diverse populations are needed. [ABSTRACT FROM AUTHOR]

Error transformation can be used to evaluate the kinematic performance of a parallel manipulator. However, the terminal error of redundantly actuated parallel manipulators is difficult to calculate from joint errors. This paper proposes a method to approximate the terminal error of a redundantly actuated parallel manipulator by taking the minimum terminal error among all corresponding nonredundant counterparts. The local Frobenius norm index (LFNI) is proposed to estimate the expectation of terminal error. Additionally, the global Frobenius norm index (GFNI) is introduced to describe the worst case of terminal error in the workspace, which is then used for the optimum design of a RPU-UPR-2UPU redundantly actuated parallel manipulator. After the optimum design, the average root mean square error of the manipulator is reduced. Furthermore, a control mode determination strategy for allocating force/position control to a certain chain is also proposed to minimize the terminal error, whose effectiveness is validated through simulation. [ABSTRACT FROM AUTHOR]

Multi-segment foot models (MFMs) provide a better understanding of the intricate biomechanics of the foot, yet it is unclear if they accurately differentiate foot type function during locomotion. We employed an MFM to detect subtle kinematic differences between foot types, including: pes cavus, neutrally aligned, and asymptomatic and symptomatic pes planus. The study investigates how variable the results of this MFM are and if it can detect kinematic differences between pathologic and non-pathologic foot types during the stance phase of gait. Independently, three raters instrumented three subjects on three days to assess variability. In a separate cohort, each foot type was statically quantified for ten subjects per group. Each subject walked while instrumented with a four-segment foot model to assess static alignment and foot motion during the stance phase of gait. Statistical analysis performed with a linear mixed effects regression. Model variability was highest for between-day and lowest for between–rater, with all variability measures being within the true sample variance. Almost all static measures (radiographic, digital scan, and kinematic markers) differed significantly by foot type. Sagittal hindfoot to leg and forefoot to leg kinematics differed between foot types during late stance, as well as coronal hallux to forefoot range of motion. The MFM had low between-rater variability and may be suitable for multiple raters to apply to a single study sample without introducing significant error. The model, however, only detected a few dynamic differences, with the most dramatic being the hallux to forefoot coronal plane range of motion. Significance: Results only somewhat aligned with previous work. It remains unclear if the MFM is sensitive enough to accurately detect different motion between foot types (pathologic and non-pathologic). A more accurate method of tracking foot bone motion (e.g., biplane fluoroscopy) may be needed to address this question. • The majority of static measures differed significantly by foot type. • Sagittal hind- and forefoot to leg kinematics differed between groups during stance. • Coronal hallux to forefoot range of motion varied by foot type during gait. • All variability measures were within the true sample variance. [ABSTRACT FROM AUTHOR]

The sit-to-stand transfer is a fundamental functional movement during normal activities of daily living. Central nervous system disorders can negatively impact the execution of sit-to-stand transfers, often impeding successful completion. Despite its importance, the neurophysiological basis at muscle (electromyography (EMG)) and brain (electroencephalography (EEG)) level as related to the kinematic movement is not well understood. This review synthesises the published literature addressing central and peripheral neural activity during 3D kinematic capture of sit-to-stand transfers. A pre-registered systematic review was conducted. Electronic databases (PubMed, CINAHL Plus, Web of Science, Scopus and EMBASE) were searched from inception using search operators that included sit-to-stand, kinematics and EMG and/or EEG. The search was not limited by study type but was limited to populations comprising of healthy individuals or individuals with a central neurological pathology. From a total of 28,770 identified papers, 59 were eligible for inclusion. Ten of these 59 studies received a moderate quality rating; with the remainder rated as weak using the Effective Public Health Practice Project tool. Fifty-eight studies captured kinematic data of sit-to-stand with associated EMG activity only and one study captured kinematics with co-registered EMG and EEG data. Fifty-six studies examined sit-to-stand transfer in healthy individuals, reporting four dynamic movement phases and three muscle synergies commonly used by most individuals to stand-up. Pre-movement EEG activity was reported in one study with an absence of data during execution. Eight studies examined participants following stroke and two examined participants with Parkinson's disease, both reporting no statistically significant differences between their kinematics and muscle activity and those of healthy controls. Little is known about the neural basis of the sit-to-stand transfer at brain level with limited focus in central neurological pathology. This poses a barrier to targeted mechanistic-based rehabilitation of the sit-to-stand movement in neurological populations. • Four dynamic movement phases are commonly used by most individuals to stand up. • Three muscle synergies are commonly used by most individuals to stand up. • No EEG data during sit-to-stand execution with 3D motion analysis was found. [ABSTRACT FROM AUTHOR]

Chronic ankle instability (CAI) has been associated with lower limb deficits that can lead to altered biomechanics during dynamic tasks. There have been contradictory findings in terms of ankle and hip joint biomechanics to date, influenced by the variety of movement tasks and varying definitions of the CAI condition. How do biomechanical variables of the lower extremity differ during walking, running, and jump-landing in individuals with CAI compared with those without CAI? Thirty-two individuals (17 CAI and 15 controls) participated in this retrospective case-control study. Sagittal and frontal plane ankle and hip joint angles and moments, and mediolateral foot balance (MLFB) were calculated during the tasks. Statistical parametric mapping (SPM) was used for the whole trajectory analysis to detect group differences. Discrete variables, including initial contact (IC) and peak angles and moments, were additionally compared. No differences were found between groups during walking. During running, the CAI group exhibited a lower plantar flexor moment (p < 0.001) and more laterally deviated MLFB (p = 0.014) during mid-stance when compared to controls. Additionally, participants with CAI had a significantly greater peak plantar flexion angle in early stance (p = 0.022) and a reduced peak plantar flexor moment (p = 0.002). In the jump-landing, the CAI group demonstrated an increased hip extensor moment (p = 0.008), and a greater peak hip adduction angle (p = 0.039) shortly after ground contact compared to the control group. Differences in ankle and hip biomechanics were observed between groups during running and jump landing, but not during walking. These differences may be indicative of impairments in the sensorimotor system or of learnt strategies adopted to try to minimise instability and injury risk and can help to inform future intervention design. • Individuals with CAI display different ankle joint biomechanics than controls during running. • Individuals with CAI display different hip joint biomechanics than controls during jump-landing. • The level of demand for the task may influence the biomechanical strategy adopted. [ABSTRACT FROM AUTHOR]

Obesity is a crucial factor that increases the risk of initiating and advancing knee osteoarthritis. However, it remains unclear how obesity directly impacts the biomechanical experience of the lower limb joints, potentially triggering or exacerbating joint degeneration. This study investigated the interactive effects of BMI augmentation on lower limb kinematics, kinetics, and muscle activations during walking. A group of 60 participants underwent a three-dimensional gait analysis. These individuals were categorized into three groups based on their body mass index (BMI): those with a BMI below 25 were classified as having a healthy weight, those with a BMI between 25 and 30 were categorized as overweight, and those with a BMI exceeding 30 were considered obese. This study analyzed the gait of 60 participants categorized by BMI. During walking trials, they recorded ground reaction forces electromyography of leg muscles like the gastrocnemii, hamstrings, and quadriceps. Lower limb joint angles and net moments were also calculated. Statistical mapping identified variations in kinematic, kinetic, and muscle activation patterns across the stance phase between BMI groups. The results displayed distinct biomechanical patterns in obese individuals. Notably, there was a significant increase in flexion observed in the hip and knee joints (P < 0.001) during the initial stance phase and an increase in hip and knee adduction angles and moments throughout the entire stance phase (P < 0.001). Additionally, muscle activations underwent significant changes (P < 0.01), with a positive correlation noted with the BMI factor. This correlation was most pronounced during the early stance phase for the quadriceps and hamstring muscles and the late stance phase for the gastrocnemius. These findings represent a comprehensive picture that contributes to understanding how excess weight and obesity influence joint biomechanics, highlighting the associated risk of joint osteoarthritis. • The study analyzes how BMI affects gait biomechanics in 60 guys aged 18-30. • Gait analysis, force plates, and motion capture analyze 3D motion, forces, and muscle activation. • Obesity increased hip/knee angles and moments, indicating biomechanical effects. • Research relates BMI to walking quadriceps, hamstring, and calf muscular activation. [ABSTRACT FROM AUTHOR]

Individuals with myelomeningocele (MMC) present with neurological and orthopaedic deficiencies, requiring orthoses during walking. Orthoses for counteracting dorsiflexion may restrict activities such as rising from a chair. How are sit-to-stand (STS) movements performed with ankle joint-restricted ankle-foot orthoses (AFO) and knee-ankle-foot orthoses with a free-articulated knee joint (KAFO-F)? Twenty-eight adults with MMC, mean age 25.5 years (standard deviation: 3.5 years), were divided into an AnkleFree group (no orthosis or a foot orthosis) and an AnkleRestrict group (AFOs or KAFO-Fs). Study participants performed the five times STS test (5STS) while their movements were simultaneously captured with a three-dimensional motion system. Centre of mass (CoM) trajectories and joint kinematics were analysed using statistical parametric mapping. The AnkleRestrict group performed the STS slower than the AnkleFree group, median 8.8 s (min, max: 6.9, 14.61 s) vs 15.0 s (min, max: 7.5, 32.2 s) (p = 0.002), displayed reduced ankle dorsiflexion (mean difference: 6°, p = 0.044) (74–81 % of the STS cycle), reduced knee extension (mean difference: 14°, p = 0.002) (17–41 % of the STS cycle), larger anterior pelvic tilt angle (average difference: 11°, p = 0.024) (12–24 % of the STS cycle), and larger trunk flexion angle (on average 4°, p = 0.029) (6–15 % of the STS cycle). The differences between the AnkleFree and AnkleRestrict groups in performing the STS seem consistent with the participants functional ambulation: community ambulation in the AnkleFree group, and household and nonfunctional ambulation with less hip muscle strength in the majority of the AnkleRestrict group. No differences in the 5STS CoM trajectories or the kinematics were found with respect to the AFO and KAFO-Fs groups. Because orthoses are constructed to enable walking, the environment needs to be adjusted for activities in daily living such as the STS movement. • Orthoses for walking require restricted ankle dorsiflexion in individuals with MMC. • A blocked ankle hampers forward movement altering sit-to-stand (STS) movements. • The effort required to perform STS in everyday activities should be acknowledged. • The findings highlight the importance of adjusting the environment with external support. [ABSTRACT FROM AUTHOR]

Three dimensional (3D) kinematic analysis based on motion capture can study synchronized data from the integrated jaw and neck motor system. Jaw function is commonly estimated on linear outcome variables of motion range. By combining jaw border movements in three planes the functional range of motion could be described by movement area and volume measures. Can we ensure the accuracy, test-retest reliability, and intra-individual variability with 3D kinematic analysis for estimating jaw functional range of motion (ROM), including jaw movement area and volume and jaw and head linear measures? Accuracy was estimated by applying the method to a set of beakers with known volume, based on the percentage deviation and Pearson correlation coefficient between target and estimated values. Test-retest reliability was then analysed on maximum jaw movements performed in a pre-determined movement sequence by 17 pain-free participants (25.4 years ± 2.4) to estimate jaw functional ROM. Intraclass correlation coefficients (ICC) were calculated, and Bland-Altman plots were constructed. Coefficient of variation (CV) tested the within session reliability. The accuracy in volume and area measurements were high with a percentage deviation (0.03±0.59) and (1.2±0.45), respectively, with a strong linear relationship (R2=0.99) between target and estimated values. The test-retest reliability showed moderate to excellent reliability, and Bland-Altman plots showed good agreement. Overall, CVs showed high repeatability, but jaw movements in horizontal directions were less reliable and presented higher variability. The study with 3D kinematic analysis of jaw functional ROM, provides a methodological basis for accurate and reliable measurements. The study presents a new way to estimate jaw functional ROM measures, useful for evaluation in clinical intervention, for instance in pain and jaw dysfunction. Moreover, the natural biological movement variability and the complexity of the interplay of jaw-head movement will be emphasised. • A new kinematic method to estimate jaw functional range of motion. • The accuracy in area and volume measurements were high. • Jaw and head linear movement displacements showed high test-retest reliability. • The method has potential to evaluate dysfunctions in jaw-neck motor system. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament injuries are serious conditions encountered in volleyball players and occur frequently during spike jump landings. During spike jumps, the lower limb kinematics and kinetics during landing may be altered in relation to the ball position. Does the ball position have an effect on lower-limb kinematics and kinetics during spike jumps? We measured the lower limb kinematics and kinetics of 20 healthy female college volleyball athletes during a spike jump using a three-dimensional motion analysis system. The ball positions were set to normal, dominant, and non-dominant positions. A repeated analysis of variance was used to compare the lower limb kinematics and kinetics at the initial contact and the maximum knee flexion during jump landing. Additionally, statistical parametric mapping analysis was used to analyze changes over time during the spike jumps. At the initial contact of the spike jump landing, the knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment when the ball was set at the non-dominant position increased compared to those at the dominant position. Statistical parametric mapping analysis showed no significant change in knee valgus angle and moment of jump landing. Knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment increased with the non-dominant position; furthermore, the risk of ACL injury may also be increased. The posture at ball impact may influence the landing kinematics and kinetics. Therefore, it is necessary to pay close attention to movements during and prior to landing. • Ball positions influenced trunk and lower limb in volleyball. • The knee valgus angle and moment were increased in non-dominant position. • The movement of trunk lateral bend during mid-flight affect the landing movement. [ABSTRACT FROM AUTHOR]

Gait kinematics differ between settings and among young and older adults with and without knee osteoarthritis. Out-of-lab data has a variety of walking bout characteristics compared to controlled in-lab settings. The effect of walking bout duration on gait analysis results is unclear, and there is no standardized procedure for segmenting or selecting out-of-lab data for analysis. Do gait kinematics differ by bout duration or setting in young and older adults with and without knee osteoarthritis? Ten young (28.1±3.5 yrs), ten older adults (60.8±3.3 yrs), and ten older adults with knee osteoarthritis (64.1±3.6 yrs) performed a standard in-lab gait analysis followed by a prescribed walking route outside the lab at a comfortable speed with four IMUs. Walking speed, stride length, and sagittal hip, knee, and ankle angular excursion (ROM) were calculated for each identified stride. Out-of-lab strides included straight-line, level walking divided into strides that occurred during long (>60 s) or short (≤60 s) bouts. Gait kinematics were compared between in-lab and both out-of-lab bout durations among groups. Significant main effects of setting or duration were found for walking speed and stride length, but there were no significant differences in hip, knee, or ankle joint ROM. Walking speed and stride length were greater in-lab followed by long and short bout out-of-lab. No significant interaction was observed between group and setting or bout duration for any spatiotemporal variables or joint ROMs. Out-of-lab gait data can be beneficial in identifying gait characteristics that individuals may not encounter in the traditional lab setting. Setting has an impact on walking kinematics, so comparisons of in-lab and free-living gait may be impacted by the duration of walking bouts. A standardized approach for to analyzing out-of-lab gait data is important for comparing studies and populations. • Setting and the duration of walking bouts have an influence on gait kinematics. • Speed and stride length were greater in vs out of lab and for long vs short bouts. • Adults respond similarly to different settings or bout durations regardless of age. [ABSTRACT FROM AUTHOR]

Gait abnormalities have been described in patients after total knee arthroplasty (TKA), leading to the development of inter-joint coordination abnormalities and increased risk of falling. Such impairments have been reported to persist in the long-term, although the majority of studies assessed gait pattern especially in the first months after TKA. What are the long-term gait impairments in patients after TKA compared to healthy age-matched subjects? A systematic search was conducted on MEDLINE/PubMed, EMBASE, CENTRAL and Scopus databases. Observational studies or randomized controlled trials investigating gait spatial-temporal, kinematic and kinetics parameters in a time-window longer than 6 months in patients with TKA compared to healthy age-matched subjects were included. Methodological quality was assessed using the modified Downs and Black (D&B) checklist and participants' characteristics, surgical procedures details and outcome measures were extracted. Pooled or un-pooled findings were categorized into "6 months - 1 year" and "more than 1 year" timepoint categories. Twenty-eight studies (976 patients) were included. Overall quality was fair with a mean modified D&B score of 63.5 %. Reduced speed, stride length, cadence and longer stance phase were found in patients when compared to healthy individuals at "6 months - 1 year" follow-up. Spatial-temporal parameters deficits were also found at more than 1 year after TKA, where lower single-limb support and longer double-limb support durations were detected. These impairments occurred in concomitance with decreased knee range of motion along the sagittal and frontal planes and altered kinetic parameters. Hip kinematic and kinetic long-term impairments were also detected after TKA. These findings highlighted long-term gait pattern alterations in patients with TKA compared to age-matched healthy subjects. Future studies should identify interventions able to reduce long-term gait pattern alterations and improve function in patients after TKA. • Long-term gait impairments were found in patients after TKA. • Lower speed, stride length, cadence and longer stance phase occurred after TKA. • Hip and knee kinematic and kinetic deficits were detected after TKA. [ABSTRACT FROM AUTHOR]

Multi-segment foot models have been used to quantify foot kinematics during walking. However, walking kinematics is not sufficient to assess hindfoot flexibility (available range of hindfoot varus-valgus motion). The modified Shriners Hospitals for Children – Greenville (mSHCG) foot model has been used to quantify hindfoot flexibility with Coleman block test (peak hindfoot valgus) and Root test (peak hindfoot varus). Sensitivity of mSHCG foot model to detect clinically relevant difference in hindfoot flexibility measures for planovalgus (PV) and cavovarus (CV) feet has not been demonstrated. Can mSHCG foot model detect statistically significant difference in hindfoot flexibility measures between PV, CV and typically developing (TD) feet? Hindfoot flexibility assessment was completed for 32 PV (37 feet), 27 CV (37 feet) and 20 TD (40 feet) individuals. Hindfoot position relative to tibia in coronal plane was measured in three postures: standing, heel raise and Coleman block test. Radiographic measures in standing position were also completed for PV and CV individuals and their correlation with hindfoot flexibility measures were evaluated. Statistically significant (p<0.001) differences were observed between three groups (TD, PV, CV) in all three hindfoot flexibility measures- (i) Hindfoot varus in standing position (ii) Peak hindfoot varus in heel raise and (iii) Peak hindfoot valgus in Coleman block test. There was relatively stronger correlation (R2=0.407–0.854) between three radiographic measures and hindfoot varus in standing position. Correlation between hindfoot range of motion towards valgus from standing to Coleman block test and the three radiographic measures was weaker (R2=0.2329–0.3042). Hindfoot flexibility assessment can detect statistically significant difference between PV, CV and TD feet and provides additional information about available dynamic range of motion of hindfoot in the coronal plane that cannot be predicted from radiographic measures. Therefore, hindfoot flexibility assessment may assist in treatment planning of foot deformities. • mSHCG foot model can be used to quantify hindfoot flexibility. • Significant difference observed in hindfoot flexibility for PV and CV feet compared to TD. • Hindfoot varus in standing position strongly correlated with radiographic measures. • Hindfoot valgus range in Coleman block test weakly correlated with radiographic measures. • Hindfoot flexibility assessment may be critical to treatment planning. [ABSTRACT FROM AUTHOR]

Wearable sensors provide the ability to assess ambulatory activity in the community after hip preservation surgery (HPS). In combination with gait analysis and patient reported outcomes, more perspective on post-operative function is gained. The purpose of this study was to assess the relationship between self-reported function/activity, temporo-spatial parameters and walking kinematics to objectively measured ambulatory activity. Forty-nine participants (38 Females; age range 16–38 years) who were five years or more post-surgery and the following diagnoses were included: Acetabular Dysplasia (n=34), Femoroacetabular Impingement (n=12) and Legg-Calvé Perthes disease (n=3). Participants underwent 3D gait analysis and gait deviations were quantified using the Gait Deviation Index (GDI) and Gait Profile Score (GPS). Temporo-spatial parameters were also calculated. Self-reported pain/function and activity level were assessed via the Harris Hip Score (HHS) and UCLA Activity Scale (UCLA). Participants wore a StepWatch Activity Monitor in their community and the Intensity/Duration of ambulatory bouts were analyzed. Spearman correlation coefficients were run to assess the following relationships: in-lab walking measures, self-reported function/activity vs.community ambulatory activity. There were no statistically significant correlations between HHS, UCLA or temporospatial parameters with ambulatory activity (p>0.05). Worsening gait deviations (GDI/GPS scores) correlated with daily total ambulatory time (ρ=0.284/-0.284, p<0.05), time spent in Short duration ambulatory bouts (ρ=-0.321/0.321, p<0.05) and the amount of time in Long duration ambulatory bouts (ρ=0.366/-0.366, p<0.05). The amount of time spent in Easy intensity/Short duration and Easy intensity/Long duration ambulatory bouts did have a weak correlation with the GDI and GPS (p<0.05). In HPS patients after long-term follow up, ambulatory activity in the community did not correlate with patient reported outcomes but there was a weak correlation with the presence of gait deviations. Incorporating wearable sensors to assess community ambulatory bout intensity/duration, provides additional quantifiable measures into the overall function of patients following HPS • Harris Hip Score did not correlate with community ambulatory activity. • Temporal spatial parameters did not correlate with community ambulatory activity. • Overall walking mechanics weakly correlate with community ambulatory activity. • Wearable sensors provide information on community ambulatory intensity/duration. [ABSTRACT FROM AUTHOR]

An ankle-foot orthosis (AFO) with plantar flexion resistance (PFR) can improve the first rocker function during gait, but the incremental changes in the resistive moment on balance and gait have not been well identified. To investigate the effect of changing the PFR moment of dynamic AFO (DAFO) on measures of the center of pressure (COP) and clinical gait outcomes in individuals with post-stroke hemiparesis. In this randomized repeated measure study of 36 stroke individuals, the customized DAFO using foot drop ankle units set in three PFR situations (low, medium, and high) was evaluated. The balance parameters for COP measures were investigated by HUMAC® Balance & Tilt System. Gait parameters and ankle kinematics were recorded using the 3D motion analysis through force platform and optoelectronic system. The comparison was made using a parametric ANOVA test and the P value was set at 0.05 for statistical significance. Significant differences were observed for COP average velocity (1.30 ± 0.64, 1.10 ± 0.05, and 1.37 ± 0.43), COP path length (43.3 ± 4.6, 33.4 ± 4.3, and 36.3 ± 5.4), walking velocity (11.0 ± 3.1, 13.2 ± 4.4, and 9.9 ± 3.5), and cadence (31.5 ± 2.0, 33.0 ± 3.1, and 29.0 ± 1.6) respectively for low, medium and high PFR settings (P < 0.05). Except for the COP path length and cadence, posthoc multiple comparisons revealed significant differences between low and medium (P < 0.05) and medium and high (P < 0.05) PFR grades. PFR with medium resistance demonstrated near-normal maximal peak ankle dorsiflexion (mean deviation of 8 degrees, P < 0.05). Medium PFR grade should be encouraged since it can enhance balance parameters like path length and average velocity of COP, increase cadence and average velocity during gait, and improve maximal peak ankle dorsiflexion. • Changes in resistive moment of plantar-flexion affects gait and balance in stroke. • The influence of PFR moment on ankle kinematics, gait and balance was examined. • Dynamic AFOs with dorsiflexion assist Klenzak joints allow for adjustable PFR. • Moderate PFR setting may improve the ankle kinematics, gait and balance parameters. • High PFR may increase non-symmetrical ankle dorsiflexion during swing. [ABSTRACT FROM AUTHOR]