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Accurate analysis of sperm cell flagellar dynamics plays a crucial role in understanding sperm motility as flagella parameters determine cell behavior in the spatiotemporal domain. In this study, we introduce a novel approach by harnessing Genetic Algorithms (GA) to analyze sperm flagellar motion characteristics and compare the results with the traditional decomposition method based on Fourier analysis. Our analysis focuses on extracting key parameters of the equation approximating flagellar shape, including beating period time, bending amplitude, mean curvature, and wavelength. Additionally, we delve into the extraction of phase constants and initial swimming directions, vital for the comprehensive study of sperm cell pairs and bundling phenomena. One significant advantage of GA over Fourier analysis is its ability to integrate sperm cell motion data, enabling a more comprehensive analysis. In contrast, Fourier analysis neglects sperm cell motion by transitioning to a sperm-centered coordinate system (material system). In our comparative study, GA consistently outperform the Fourier analysis-based method, yielding a remarkable reduction in fitting error of up to 70% and on average by 45%. An in-depth exploration of the sperm cell motion becomes indispensable in a wide range of applications from complexities of reproductive biology and medicine, to developing soft flagellated microrobots.

In order to solve the problem of efficient trajectory control of centimeter-scale robots with small size, a small jellyfish robot (JRT) is designed and developed, which is composed of an air chamber, a center of gravity adjustment device and a jellyfish-inspired thruster with a size of only ⌀6.8 cm × 5.3 cm. Its trajectory can be effectively controlled underwater through the coordination of the center of gravity adjustment device and jellyfish-inspired thruster. Underwater experiments verify the function of JRT swimming and hovering in the vertical direction, horizontal directional swimming, and horizontal ejection. By analyzing the force balance relationship and motion state data of JRT swimming in the vertical and horizontal directions, a trajectory control scheme is proposed. The speed of horizontal directional swimming can reach 1.7 cm/s, and the trajectory deviation is 0—3.4 cm, which shows that the JRT has a good trajectory control ability and is expected to be applied in underwater resource exploration, environmental monitoring, and other fields.

[Objective] To deal the technical difficulties in further realizing the automation of de nucleating production of fresh peach slices. [Methods] A new type of fresh peach slicing and coining machine was designed. The cutting tool for slice kerning was simplified and analyzed by Mathematical analysis, and the motion characteristic equation and curve of the mechanism were obtained. The motion simulation analysis of the slicing and core-removing tool mechanism was carried out by using SolidWorks Motion software, and the motion characteristic curve of the mechanism was obtained.The correctness of the mathematical analysis was verified, and the rationality of the design of the cutting tool was also verified. [Results] The machine uses PLC control, including fresh peach conveyor chain feeding, fresh peach positioning, slicing tool movement, etc. Through the analysis of the field test results, the average cutting rate of fresh peach slicing and coiling machine reached 99.39%, the average coiling rate reached 99.15%, and the average breakage rate was lower than 0.12%. [Conclusion] The new type of fresh peach slicing and coiling machine can realize the automatic positioning, cutting and coiling of fresh peach, etc.

Abstract Background Systems that capture motion under laboratory conditions limit validity in real-world environments. Mobile motion capture solutions such as Inertial Measurement Units (IMUs) can progress our understanding of "real" human movement. IMU data must be validated in each application to interpret with clinical applicability; this is particularly true for diverse populations. Our IMU analysis method builds on the OpenSim IMU Inverse Kinematics toolkit integrating the Versatile Quaternion-based Filter and incorporates realistic constraints to the underlying biomechanical model. We validate our processing method against the reference standard optical motion capture in a case report with participants with transfemoral amputation fitted with a Percutaneous Osseointegrated Implant (POI) and without amputation walking over level ground. We hypothesis that by using this novel pipeline, we can validate IMU motion capture data, to a clinically acceptable degree. Results Average RMSE (across all joints) between the two systems from the participant with a unilateral transfemoral amputation (TFA) on the amputated and the intact sides were 2.35° (IQR = 1.45°) and 3.59° (IQR = 2.00°) respectively. Equivalent results in the non-amputated participant were 2.26° (IQR = 1.08°). Joint level average RMSE between the two systems from the TFA ranged from 1.66° to 3.82° and from 1.21° to 5.46° in the non-amputated participant. In plane average RMSE between the two systems from the TFA ranged from 2.17° (coronal) to 3.91° (sagittal) and from 1.96° (transverse) to 2.32° (sagittal) in the non-amputated participant. Coefficients of Multiple Correlation (CMC) results between the two systems in the TFA ranged from 0.74 to > 0.99 and from 0.72 to > 0.99 in the non-amputated participant and resulted in ‘excellent’ similarity in each data set average, in every plane and at all joint levels. Normalized RMSE between the two systems from the TFA ranged from 3.40% (knee level) to 54.54% (pelvis level) and from 2.18% to 36.01% in the non-amputated participant. Conclusions We offer a modular processing pipeline that enables the addition of extra layers, facilitates changes to the underlying biomechanical model, and can accept raw IMU data from any vendor. We successfully validate the pipeline using data, for the first time, from a TFA participant using a POI and have proved our hypothesis.

Abstract Background Movement is a defining aspect of animals, but it is rarely studied using quantitative methods in microscopic invertebrates. Bdelloid rotifers are a cosmopolitan class of aquatic invertebrates of great scientific interest because of their ability to survive in very harsh environment and also because they represent a rare example of an ancient lineage that only includes asexually reproducing species. In this class, Adineta ricciae has become a model species as it is unusually easy to culture. Yet, relatively little is known of its ethology and almost nothing on how it behaves during feeding. Methods To explore feeding behaviour in A. ricciae, as well as to provide an example of application of computational ethology in a microscopic invertebrate, we apply Procrustes motion analysis in combination with ordination and clustering methods to a laboratory bred sample of individuals recorded during feeding. Results We demonstrate that movement during feeding can be accurately described in a simple two-dimensional shape space with three main ‘modes’ of motion. Foot telescoping, with the body kept straight, is the most frequent ‘mode’, but it is accompanied by periodic rotations of the foot together with bending while the foot is mostly retracted. Conclusions Procrustes motion analysis is a relatively simple but effective tool for describing motion during feeding in A. ricciae. The application of this method generates quantitative data that could be analysed in relation to genetic and ecological differences in a variety of experimental settings. The study provides an example that is easy to replicate in other invertebrates, including other microscopic animals whose behavioural ecology is often poorly known.

Abstract: This study presents a new method to analyse the motion of moving objects. The novelty of this study is that the presented work obtains your location based on the coupled measured data using the GPS and other motion sensors of a smart phone. This method can be used for GPS free navigations in future studies. The smartphone sensors measure the desired values and a developed Android application records this data. A developed MATLAB code analyses these values for car road travel using multiple coordinate transformations and removes the effects of Earth's gravity from the measured acceleration. It is recognized that the presented method can be used to analyse the movement and performance of the studied material. The obtained results show that the integration of data recorded by the accelerometer sensor integrates the effects of noise and this sensor is not a convenient feature to obtain the instantaneous location. Calculating the acceleration using GPS data may also not be accurate in this case. Getting the location and acceleration using a GPS sensor and accelerometer is more accurate.

Abstract Staircases are a frequently encountered obstacle in daily life, requiring individuals to navigate ascending and descending movements that place additional demands on the trunk and lower limbs compared to walking on level surfaces. Therefore, it is crucial to examine the biomechanical characteristics of the trunk and lower limbs in individuals with scoliosis during stair activity. The aim of this study was to investigate the biomechanical differences in trunk and lower limbs during daily stair activities between patients with scoliosis and a healthy population. Additionally, the study aimed to explore the relationship between trunk abnormalities and lower limb biomechanics, providing a clinical and objective assessment basis for scoliosis. The Qualisys system, based in Gothenburg, Sweden, was employed for data collection in this study, with a sampling frequency of 150 Hz. It captured the kinematics of the trunk and lower limbs, as well as the kinetics of the lower limbs during stair ascent and descent for both the 28 individuals with scoliosis and the 28 control participants. The results indicate that scoliosis patients demonstrated significantly higher asymmetry compared to the control group in various measures during ascent and decent. These include different parts of kinematics and kinetics. Scoliosis patients demonstrate noticeable variations in their movement patterns compared to the healthy population when engaging in stair activities. Specifically, during stair ascent, scoliosis patients exhibit a seemingly more rigid movement pattern, whereas descent is characterized by an unstable pattern.

Companies are becoming increasingly aware of the health of their employees and are now integrating exoskeleton solutions for both prevention and job maintenance. However, the effect of using exoskeletons is still an open question. Therefore, this study aimed to evaluate the impact of an active lumbar exoskeleton and its passive belt on trunk kinematics and muscle activity using instrumented motion analysis. Twenty-three healthy subjects volunteered to perform three handlings of a 5 kg load (free lifting, squat lifting, and load transfer) under three different experimental conditions. The “Control” condition was when the subject did not wear any device, the “Belt” condition was when the subject wore only the passive part of the exoskeleton, and the “Exo” condition was when the subject wore the active exoskeleton. Based on the Rapid Upper Limb Assessment scale, the exoskeleton reduced the time spent in angles that were considered dangerous for the back, according to ergonomic evaluations. Furthermore, for the handling sessions, it was observed that the exoskeleton did not modify muscle activity in the abdominal–lumbar region.

Background Although My Jump 2® consistently presented excellent values of reliability and validity when compared to force platforms (FPs) and contact mats, to date no scientific investigation assessed the validity and reliability of My Jump 2® to measure jump height in visually impaired five-a-side soccer athletes. Thus, the study aimed at analyzing the validity and reliability of the My Jump 2® to measure the vertical jump of five-a-side soccer athletes. Methods Twelve visually impaired five-a-side soccer athletes, volunteered for this study. Each player performed five countermovement jumps (CMJs) and squat jumps (SJs) on a contact platform (CP) while they were simultaneously recorded using My Jump 2®. Results There was almost perfect agreement between the My Jump 2® and the contact platform measurements of CMJ (intraclass correlation coefficient = 0.99; p < 0.001) and SJ (intraclass correlation coefficient = 0.99; p < 0.001), heights for athletes during the first and second measurement days. Bland-Altman analysis showed a bias of 0.25 ± 0.5 cm; maximum SD = 1.3; minimum SD = −0.88 for CMJ, while that Bland-Altman analysis showed bias 0.18 ± 0.5 cm; maximum SD = 1.3; minimum SD = −0.96, for SJ. Conclusion We can conclude that the My Jump 2® is a valid and reliable method to measure CMJ and SJ in visually impaired five-a-side soccer athletes.

Sprint performance is a critical factor in soccer. While previous studies have extensively explored the biomechanical, physiological, and metabolic determinants of sprinting, the impact of anthropometric variables in team sports contexts, especially soccer, remains underexplored. This study aims to investigate the influence of anthropometric and mechanical variables on sprint performance in young soccer players. Fifty-eight young soccer players were evaluated in anthropometry and a 30-meter (m) sprint using radar technology. Split times in 5, 15, and 30 m were determined, in addition to the assessment of the force-velocity profile proposed by Morin and Samozino. Results: Key anthropometric variables associated with improved sprint performance included lower-limb muscle mass at distances 5 and 15 m (R2 = 0.08 and R2 = 0.09, respectively, both with small effects). Additionally, body composition, particularly a lower % body fat, was crucial across all sprint distances (ES: large). Among the mechanical variables, max power (R2 = 0.997, ES: large) and maximum velocity (R2 = 0.553, ES: large) are the mechanical variables that were most strongly associated with sprint performance over distances greater than 30 m. Soccer coaches, athletic trainers, and strength and conditioning specialists working with young athletes can apply the findings of this study to their training programming.

This study introduces a novel surrogate safety indicator, the ‘effective radius’, and a dynamic tracking methodology for assessing the safety of micromobility (MM) users on isolated bike lane curves, with a focus on geometric characteristics. The methodology involves six main pillars, including site selection, geometric data collection, video recording, speed and position extraction, visualization, and analysis. Naturalistic video data of bike lane users are captured to observe user behavior, and specific points along the curve centerline are identified for monitoring lateral position and speed on a selected curve site in Valencia, Spain. The analysis centers on a bidirectional bike lane featuring a sharp horizontal curve, incorporating the effective radius criteria to evaluate MM users' responses to geometry and environmental conditions. Findings reveal significant variation in effective radius, especially during left turns, primarily due to the geometry factor and the lane's positioning outside the curve. Lateral displacement heat maps indicate that left-turn users often have higher tendencies to violate dedicated lanes, posing collision risks. The speed analysis underscores potential conflicts and reduced handling capabilities for users breaching lane boundaries. The imperative need for well-informed design and safety measures in micromobility infrastructure is emphasized, considering the impact of geometric factors on user behavior and safety.

Background: The consensus on anterior cruciate ligament (ACL) injury prevention involves the suppression of dynamic knee valgus (DKV). The gold standard for evaluating the DKV includes three-dimensional motion analysis systems; however, these are expensive and cannot be used to evaluate all athletes. Markerless motion-capture systems and joint angle calculations using posture estimation have been reported. However, there have been no reports on the reliability and validity of DKV calculations using posture estimation. Research question: This study aimed to clarify the reliability and validity of DKV calculation using posture estimation. Methods: Fifteen participants performed 10 single-leg jump landings from a height of 20 cm, and the knee joint angle was calculated using joint points measured using machine learning (MediaPipe Pose) and motion-capture systems (VICON MX). Two types of angle calculation methods were used: absolute value and change from the initial ground contact (IC). Intra- and inter-rater reliabilities were examined using intraclass correlation coefficients, and concurrent validity was examined using Pearson's correlation coefficients. To examine intra-examiner reliability, we performed single-leg jump landings at intervals of ≥3 days. Results: The calculation by MediaPipe Pose was significantly higher than that by the 3-D motion analysis systems (p 0.05). No significant concurrent validity was found in the absolute value, which was significantly correlated with the change in IC. Although the inter-rater reliability of the absolute value was low, the change in IC showed good reliability and concurrent validity. Significance: The results of this research suggest that the DKV calculation by pose estimation using machine learning is practical, with normalization by the angle at IC.

ObjectiveSharp force injury has been and will remain to be a major cause of violent death; however, scientific evaluations on the impact of body posture of the victim and gender of the perpetrator on sharp force injury have been scarce. The purpose of this study was to evaluate the biomechanical characteristics found in individuals (male and female) when using a Chinese kitchen knife to slash the neck of a dummy while it was in the standing and supine positions. This work offers a solid basis for forensic identifications, criminal investigations, and court trials.MethodsA total of 12 male and 12 female college students participated in this study. Kinematic, kinetic, and surface electromyography (sEMG) data were evaluated when slashing the neck of a dummy while it was in the standing and supine positions using a Chinese kitchen knife.ResultsWhen slashing the neck of a standing dummy, participants showed shorter contact time (19.5%) and slower shoulder velocities (30.9%) as well as higher hip velocity (26.0%) and increased root mean square (RMS) and integral electromyography (iEMG) for the anterior deltoid (51.3% and 51.2%, respectively) compared to those while the dummy was in the supine position (all p < 0.05), regardless of gender. When slashing a dummy’s neck while it was in standing and supine positions, male participants showed higher shoulder, elbow, and wrist velocities (22.6%, 22.7%, and 24.4%, respectively) and higher slashing velocity (19.8%), slashing force (24.2%), and energy (46.2%) than female participants (all p < 0.05). In addition, male participants showed shorter contact time (17.8%), and the values of RMS and iEMG of the anterior deltoid, biceps brachii, extensor carpi radialis longus, and flexor carpi ulnaris were less than those of female participants (98.9%, 47.3%, 65.6%, and 33.4% for RMS and 115.1%, 59.4%, 80.1%, and 47.8% for iEMG, respectively).ConclusionThere was no difference in slashing speed, slashing force, and energy when using a Chinese kitchen knife to slash the dummy’s neck while it was in different body postures (standing and supine), suggesting a similar level of injury severity. However, there were significant differences in slashing action patterns between the two body postures, with longer contact time, smaller hip velocity, greater shoulder velocity, and less muscle activation level of the deltoid exertion when slashing the dummy’s neck in the supine position. Gender may have a greater effect on the severity of slashing, and the gender difference may be partly related to the body weight difference. The findings from this study may provide quantitative indicators and references for analyzing the motive behind the crime, as well as for case reconstruction, and for the court’s conviction and sentencing processes.

Abstract Introduction Recently, interest in quantifying upper limb function in cerebral palsy has grown. However, the lack of reference tasks and protocols, have hindered the development of quantified movement analysis in clinical practice. This study aimed to evaluate existing instrumented assessments of upper limb function in cerebral palsy, with a focus on their clinical applicability, to identify reasons for the lack of adoption and provide recommendations for improving clinical relevance and utility. Methods A systematic review was conducted by a multidisciplinary team of researchers and clinicians (Prospero CRD42023402382). PubMed and Web of Science databases were searched using relevant keywords and inclusion/exclusion criteria. Results A total of 657 articles were initially identified, and after the selection process, 76 records were included for analysis comprising a total of 1293 patients with cerebral palsy. The quality assessment of the reviewed studies revealed a moderate overall quality, with deficiencies in sample size justification and participant information. Optoelectronic motion capture systems were predominantly used in the studies (N = 57/76). The population mainly consisted of individuals with spastic cerebral palsy (834/1293) with unilateral impairment (N = 1092/1293). Patients with severe functional impairment (MACS IV and V) were underrepresented with 3.4% of the 754 patients for whom the information was provided. Thirty-nine tasks were used across the articles. Most articles focused on unimanual activities (N = 66/76) and reach or reach and grasp (N = 51/76). Bimanual cooperative tasks only represented 3 tasks present in 4 articles. A total of 140 different parameters were identified across articles. Task duration was the most frequently used parameter and 23% of the parameters were used in only one article. Conclusion Further research is necessary before incorporating quantified motion analysis into clinical practice. Existing protocols focus on extensively studied populations and rely on costly equipment, limiting their practicality. Standardized unimanual tasks provide limited insights into everyday arm use. Balancing methodological requirements and performance evaluation flexibility is a challenge. Exploring the correlation between outcome parameters and therapeutic guidance could facilitate the integration of quantified movement assessment into treatment pathways.

The advent of computer technology and the modernization of sports education have led to an increasing reliance on intelligent technology in the field of sports education. To improve the application effect of intelligent technology in physical education, a volleyball motion analysis technology combined with pose estimation optimization algorithm is designed. During the process, Kinect collects the joint data of the research object, which is then combined with the commonly used background subtraction and frame difference optimization techniques. This results in the construction of a background model. The background update number in the initial frame is utilized as the reference value. The contour edge is smoothed through the application of a one-dimensional Gaussian kernel function, and a teaching action guidance system is designed. The experimental results showed that the average accuracy of the research method reached 79.7 % and the average recall rate reached 75.2 %. The average relative error of the method was 4.13 % when comparing the accuracy of human body model. The research method is validated to accurately capture and analyze volleyball motion, which can provide some technical help for sports teaching.

IntroductionWhen walking and stepping over an obstacle of a certain height, tripping occurs more frequently with the trailing limb than the leading limb. The present study was designed to address whether collisions involving the trailing limb can be improved with experimental manipulation of the placement of the leading limb after stepping over an obstacle. We used an immersive, virtual obstacle-crossing task to ensure that the collision was not improved simply due to the experience of physical collision with an obstacle.MethodsFourteen young participants (12 males and 2 females, 28.7 ± 3.5 years) were required to walk and step over a virtual horizontal pole under one of four conditions. In three conditions, participants were required to place their leading foot on a square target located along their walking path after crossing the obstacle. The target was positioned so that it was relatively close to the obstacle (10 cm from the obstacle, referred to hereafter as the closer condition), at a position that would naturally be stepped on in successful trials without a collision (20 cm from the obstacle, the middle condition), or relatively far from the obstacle (40 cm from the obstacle, the farther condition). For the fourth condition, participants were free to select where they would step after stepping over the obstacle (the control condition).Results and discussionThe results showed that the collision rate of the trailing limb was significantly lower under the closer condition than under the other three conditions. Compared to the control condition, under the closer condition the movement of the trailing limb was modified so that obstacle crossing was performed at approximately the moment when the height of the toe of the trailing limb was higher, and the walking speed was slower. These findings suggest that placing the foot of the leading limb closer to the obstacle after crossing the obstacle may ensure safe obstacle avoidance by the trailing limb.

Despite residual functional deficits clinically observed in conservatively treated mid-shaft clavicle fractures, no study has reported a quantitative assessment of the treatment effects on the kinematics of the shoulder complex during functional movement. Using computerised motion analysis, the current study quantified the 3D residual kinematic deviations or strategies of the shoulder complex bones during multi-plane elevations in fifteen patients with conservatively treated mid-shaft clavicle fractures and fifteen healthy controls. Despite residual clavicular malunion, the patients recovered normal shoulder kinematics for arm elevations up to 60° in all three tested planes. For elevations beyond 60°, normal clavicle kinematics but significantly increased scapular posterior tilt relative to the trunk was observed in the patient group, leading to significantly increased clavicular protraction and posterior tilt relative to the scapula (i.e., AC joint). Slightly different changes were found in the sagittal plane, showing additional changes of increased scapular upward rotations at 90° and 120° elevations. Similar kinematic changes were also found on the unaffected side, indicating a trend of symmetrical bilateral adaptation. The current results suggest that shoulder kinematics in multi-plane arm elevations should be monitored for any compromised integrated motions of the individual bones following conservative treatment. Rehabilitation strategies, including muscle strengthening and synergy stability training, should also consider compensatory kinematic changes on the unaffected side to improve the bilateral movement control of the shoulder complex during humeral elevation.

IntroductionAs motion capture technology becomes more popular for athlete monitoring and return-to-play evaluation, it is imperative that trunk mechanics are modeled similarly across participants. The purpose of this study was to determine how adjusting marker placement at the sternum or removing potentially occluded markers for purposes of tracking the trunk segment influences trunk kinematics during gait and a drop vertical jump (DVJ).MethodsSagittal plane trunk angles of 18 participants were computed for a Definition Model and three trunk model variations. Model variations were specifically chosen to avoid difficulties with placement of the sternum and/or thorax markers in female participants due to sports bra coverage and/or occlusion. Intraclass correlation coefficients were computed per trunk model variation to determine agreement with the Definition Model.ResultsThe Mid-Sternum model, in which the xiphoid process marker was adjusted to the midpoint of the xiphoid process and jugular notch, exhibited the least discrepancies and excellent agreement with the Definition Model across both tasks. Alternatively, the No-Thorax model, in which the thorax marker was removed, exhibited the greatest kinematic differences during the DVJ and moderate to excellent agreement across both tasks.ConclusionThe marker set chosen to track trunk motion during dynamic tasks must include locations that can be placed similarly on all participants. Based on these findings, the xiphoid process marker may be adjusted superiorly prior to the collection of dynamic trials. The recommended model for tracking the trunk segment includes marker placements on the jugular notch, mid-sternum, and 1st and 10th thoracic spinous processes.

Abstract This study compared the joint kinematics between the front squat (FS) conducted in the upright (natural gravity) position and in the supine position on a short arm human centrifuge (SAHC). Male participants (N = 12) with no prior experience exercising on a centrifuge completed a FS in the upright position before (PRE) and after (POST) a FS exercise conducted on the SAHC while exposed to artificial gravity (AG). Participants completed, in randomized order, three sets of six repetitions with a load equal to body weight or 1.25 × body weight for upright squats, and 1 g and 1.25 g at the center of gravity (COG) for AG. During the terrestrial squats, the load was applied with a barbell. Knee (left/right) and hip (left/right) flexion angles were recorded with a set of inertial measurement units. AG decreased the maximum flexion angle (MAX) of knees and hips as well as the range of motion (ROM), both at 1 and 1.25 g. Minor adaptation was observed between the first and the last repetition performed in AG. AG affects the ability to FS in naïve participants by reducing MAX, MIN and ROM of the knees and hip.

The utilization of tools provided by CAD software has become an essential component of any design process in modern mechanical design. These tools provide a simplified design methodology that does not require expert knowledge for the design of complex mechanical parts. Gears, as one of the most used mechanical components, have precisely defined and well-understood several types of tooth geometry. However, different shapes of tooth profiles cannot be easily analyzed and designed without knowledge of mathematics and analytical geometry. With modern design tools, especially CAD software, that knowledge is not necessarily required in the design process. Engineers can simply define the relative motion of one component to produce all necessary parameters that define the shape and geometry of another component.

The utilization of tools provided by CAD software has become an essential component of any design process in modern mechanical design. These tools provide a simplified design methodology that does not require expert knowledge for the design of complex mechanical parts. Gears, as one of the most used mechanical components, have precisely defined and well-understood several types of tooth geometry. However, different shapes of tooth profiles cannot be easily analyzed and designed without knowledge of mathematics and analytical geometry. With modern design tools, especially CAD software, that knowledge is not necessarily required in the design process. Engineers can simply define the relative motion of one component to produce all necessary parameters that define the shape and geometry of another component.

This paper aims to improve the design of a seat slider mechanism for an automotive seating system. The seating track mechanism comprises various parts, such as the track bar, upper slider rail, lower slider rail, and locking/unlocking mechanism. The upper rail holds the seat and manikin weight, whereas the lower rail is secured with mounting brackets. A Computer-aided design model of the proposed modified locking/unlocking mechanism of the seating track is created and conducted Finite Element Analysis (FEA). Also, the study includes the motion and dynamic analysis of the seating track mechanism using the bond graph technique by considering the mechanism with an equivalent spring-mass-damper system. The FEA ensured the design strength and its safety regarding failure analysis, whereas the motion analysis confirmed the suitability of the mechanism's kinematics. It is found that the maximum stress is developed at the track bar, i.e., 186.35 MPa, whereas the track displacement reaches its final design position, i.e., 175 mm in 2 s, when the applied force on the track bar is 100 N and on each slider is 20 N. The study ensures an alternative spring-less locking/unlocking mechanism for the seat slider mechanism.

Objective: Low-cost, portable RGB-D cameras with integrated motion tracking functionality enable easy-to-use 3D motion analysis without requiring expensive facilities and specialized personnel. However, the accuracy of existing systems is insufficient for most clinical applications, particularly when applied to children. In previous work, we developed an RGB-D camera-based motion tracking method and showed that it accurately captures body joint positions of children and young adults in 3D. In this study, the validity and accuracy of clinically relevant motion parameters that were computed from kinematics of our motion tracking method are evaluated in children and young adults. Methods: Twenty-three typically developing children and healthy young adults (5-29 years, 110–189 cm) performed five movement tasks while being recorded simultaneously with a marker-based Vicon system and an Azure Kinect RGB-D camera. Motion parameters were computed from the extracted kinematics of both methods: time series measurements, i.e., measurements over time, peak measurements, i.e., measurements at a single time instant, and movement smoothness. The agreement of these parameter values was evaluated using Pearson’s correlation coefficients r for time series data, and mean absolute error (MAE) and Bland-Altman plots with limits of agreement for peak measurements and smoothness. Results: Time series measurements showed strong to excellent correlations (r-values between 0.8 and 1.0), MAE for angles ranged from 1.5 to 5 degrees and for smoothness parameters (SPARC) from 0.02-0.09, while MAE for distance-related parameters ranged from 9 to 15 mm. Conclusion: Extracted motion parameters are valid and accurate for various movement tasks in children and young adults, demonstrating the suitability of our tracking method for clinical motion analysis. Clinical Impact: The low-cost portable hardware in combination with our tracking method enables motion analysis outside of specialized facilities while providing measurements that are close to those of the clinical gold-standard.

In most real world rehabilitation training, patients are trained to regain motion capabilities with the aid of functional/epidural electrical stimulation (FES/EES), under the support of gravity-assist systems to prevent falls. However, the lack of motion analysis dataset designed specifically for rehabilitation-related applications largely limits the conduct of pilot research. We provide an open access dataset, consisting of multimodal data collected via 16 electromyography (EMG) sensors, 6 inertial measurement unit (IMU) sensors, and 230 insole pressure sensors (IPS) per foot, together with a 26-sensor motion capture system, under different MOVEments and POstures for Rehabilitation Training (MovePort). Data were collected under diverse experimental paradigms. Twenty four participants first imitated multiple normal and abnormal body postures including (1) normal standing still, (2) leaning forward, (3) leaning back, and (4) half-squat, which in practical applications, can be detected as feedback to tune the parameters of FES/EES and gravity-assist systems to keep patients in a target body posture. Data under imitated abnormal gaits, e.g., (1) with legs raised higher under excessive electrical stimulation, and (2) with dragging legs under insufficient stimulation, were also collected. Data under normal gaits with low, medium and high speeds are also included. Pathological gait data from a subject with spastic paraplegia further increases the clinical value of our dataset. We also provide source codes to perform both intra- and inter-participant motion analyses of our dataset. We expect our dataset can provide a unique platform to promote collaboration among neurorehabilitation engineers.

Fine motor skills have been suggested to be related to human cognitive abilities. To develop an objective method for evaluating fine motor skills, we applied a flexible tactile sensor based on electrical impedance tomography (EIT) and the contact resistance principle to a cylinder designed to mimic the peg used in the Functional Dexterity Test. Six pinching motions were classified to confirm the feasibility of the prototype system. Two types of classification were performed: classification using reconstructed images and classification using measured voltage vectors. The feasibility of the classification method was evaluated using adult participants, and it was demonstrated that the system can accurately classify various types of pinching motions. The results revealed that utilizing reconstructed images for classification achieved a classification accuracy of 79.4%, while employing measured voltage vectors for classification resulted in a classification accuracy of 91.4%. These findings underscore the potential for developing an automated finger motion analysis system using EIT-based tactile sensor.

PURPOSE This study aims to analyze the effects of injury prevention video feedback on kinetic variables of the knee joint during the cutting maneuver. METHODS Twenty-eight healthy men participated and motion and force data were collected using infrared cameras, a force plate, and a Witty timing system. Paired t-tests were employed for data evaluation using the SPSS 26.0 program. RESULTS Results showed increased abduction and lateral rotation angles of the knee joint at the lower height of the center of mass (COM) (p

This study aimed to compare force plate, motion analysis, and mobile application methods for calculating vertical jump height. Twenty-nine male college students (age: 22.4 ± 1.0 years; height: 178.1 ± 6.2cm; body weight: 71.2 ± 8.0 kg) voluntarily participated in the study. Two countermovement jumps (CMJ) with 1-minute intervals on a force platform (BERTEC 4060-10) were performed. The countermovement jump performances were captured using an iPhone 11 (Apple Inc., USA). The experimental setup involved using three high-speed cameras, specifically the My Jump 2 and SIMI Motion 7.5. Obtained results from hip displacement (HD) data with motion analysis system showed that participants had significantly lower vertical jump height calculated from motion capture (p = 0.01; -8.3 ± 3.86, 95%CI; MyJump2-SIMI_HD = 1.24/3.30). It was also found that calculations from left and right foot displacement were higher than My Jump 2 results (95%CI; MyJump2-SIMI_RF = 0.66/2.93) and 95%CI (MyJump2-SIMI_LF) = (-0.63/2.65). In contrast, force plate calculations, known as the gold standard in the literature, were very similar to My Jump (95%CI; MyJumpII-FP) = (2.38/4.01). The findings indicate that the My Jump 2, used for assessing vertical jump height, may be a reliable alternative for determining vertical jump height instead of setting up gold standard methods. Individuals' athletic performance abilities and birth, gender, and sports preferences should be considered. Finally, when coaches or sports scientists intend to measure CMJ, My Jump 2 application can be recommended as a laboratory application as well as a practical and valid measurement method, especially for field applications.

Abstract Background Reference values for normal knee kinematics were limited in Asian population and were influenced by race and other factors. This study was aimed to establish the reference values and identify the factors associated with knee kinematics in healthy Thai adults, aged 18–40 years. Methods A retrospective cohort study was conducted between 2016 and 2020. Healthy Thai adults aged 18–40 years old with body mass index (BMI) between 18.5 and 24.9 kg/m2 were included. All eligible participants were attached with reflective markers. Their walking was captured by 8-digital cameras, and assessed by motion analysis software. The primary outcomes were average knee kinematic data (degrees) in three dimensional planes as valgus-varus, flexion-extension, and internal-external rotation. Paired t-test and multiple linear regression were applied to compare the outcomes and to determine their associated factors. Results Ninety-eight participants (60 females and 38 males) were included with mean age 28.5 ± 5.4 years, and BMI 21.1 ± 2.0 kg/m2. Knee kinematics showed slight adduction during the swing phase, flexion during the stance phase, and obvious external rotation throughout the gait cycle, with a peak of 30–31 degrees during mid-swing. Right knee was significantly more adducted, flexed and externally rotated than the left side, particularly at mid-stance (P = 0.047, 0.017, and

To address the limitations of current cabbage harvesters in China, which are often designed for a single variety and lack adaptability to different cabbage varieties, we developed an electric side-mounted cabbage harvester suitable for field operations in the Jiangsu region of China. This design is informed by the statistical analysis of the physical and agronomic parameters of major cabbage varieties. The harvester consists of key components, including an extraction device, a leaf-stripping device, a clamping and conveying device, and a root-cutting device. Powered by a 120 Ah direct current (DC) power source, it is capable of performing cabbage extraction, feeding, clamping, conveying, root cutting, and boxing in a single operation for three hours. Through theoretical analysis of the key components, specific parameters were determined, and field tests were conducted to verify the design. The results of the field experiments indicate that all components of the cabbage harvester operated effectively. Optimal performance was observed when the extraction roller speed was set between 100 and 110 RPM, the conveyor belt speed at 60 RPM, and the cutter speed between 160 and 220 RPM, resulting in a low cabbage harvest loss rate. The harvest loss rates from the three experiments were 11.3%, 13.3%, and 12%, respectively, which meets the mechanical harvesting requirements for cabbage.

With the advancement of deep-sea exploration, the demand for underwater manipulators capable of long-duration heavy-duty operations has intensified. Water-hydraulic systems exhibit less viscosity variation with increasing depth than oil-based systems, offering better adaptability to deep-sea conditions. Using seawater as the driving medium inherently eliminates issues such as oil contamination by water, frequent maintenance limiting underwater operation time, and environmental pollution caused by oil leaks. This paper introduces a deep-sea manipulator directly driven by seawater from the deep-sea environment. To address the challenges of weak lubrication and high corrosion associated with water hydraulics, a reciprocating plunger seal was adopted, and a water-hydraulic actuator was developed. The installation positions of actuator hinges and maximum output force requirements were optimized using particle swarm optimization (PSO), effectively reducing the manipulator’s self-weight. Through kinematic and inverse kinematic analyses and joint performance tests, a six-degree-of-freedom water-hydraulic manipulator was designed with a maximum reach of 2.5 m, a lifting capacity of 5000 N, and end-effector positioning accuracy within 18 mm.

Few studies have reported on the validity of a sensor-based lower-limb kinematics evaluation during the timed up and go (TUG) test. This study aimed to determine the validity of a wearable gait sensor system for measuring lower-limb kinematics during the TUG test. Ten young healthy participants were enrolled, and lower-limb kinematics during the TUG test were assessed using a wearable gait sensor system and a standard optical motion analysis system. The angular velocities of the hip, knee, and ankle joints in sit-to-stand and turn-to-sit phases were significantly correlated between the two motion analysis systems (R = 0.612–0.937). The peak angles and ranges of motion of hip, knee, and ankle joints in the walking-out and walking-in phases were also correlated in both systems (R = 0.528–0.924). These results indicate that the wearable gait sensor system is useful for evaluating lower-limb kinematics not only during gait, but also during the TUG test.

Purpose The aim of this study was to assess the reliability and validity of the My Jump 2® app in measuring jump height, flight time, and peak power among elite women beach volleyball players on sand surfaces. Methods Eleven elite female beach volleyball players (aged 23.6 ± 6.2 years; weight 66.3 ± 5.8 kg; height 174.4 ± 5.8 cm; with 8.4 ± 4.8 years of professional experience) participated in this study. Each player performed six countermovement jumps in a wooden box filled with sand on a force platform while simultaneously recording a video for subsequent analysis using the My Jump 2® app. Results We found excellent agreement for flight time, jump height and peak power between observers (ICC = 0.92, 0.91 and 0.97, respectively). No significant differences between force platform and My Jump 2® app were detected in the values obtained for the three variables (P > 0.05). For the force platform and the My Jump 2® app, we found a good agreement measuring jump height and flight time (ICC = 0.85 and 0.85, respectively). However, we only found a moderate agreement for peak power (ICC = 0.64). The difference in jump height showed a limit of agreement between −4.10 and 4.74 cm in Bland-Altman, indicating a high level of agreement between the two measurement tools. Conclusion Based on our findings, the My Jump 2® app reveals a valid tool for measuring jump height and flight time of CMJ on sand surfaces. However, more caution is needed when measuring peak power.

A skin marker-based motion capture model providing measures of scapular rotations was recently developed. The aim of this study was to investigate the concurrent validity and the interrater reliability of the model. Shoulder range of motion (RoM) and activities of daily living (ADL) were tested in healthy volunteers with reflective markers on the scapula and thorax. To investigate the validity, the model was compared to simultaneous data collection from markers on a scapular intracortical pin. The interrater reliability was tested by comparing the skin marker-based protocol performed by two investigators. The mean root mean square error (RMSE) and the intraclass correlation coefficient (ICC(2,1)) were calculated to determine the validity and the interrater reliability, respectively. Eight subjects were included in the validity test: female/male = 2/6, mean (SD) age 35.0 (3.0) and BMI 23.4 (3.3). The mean RMSE of all scapular rotations ranged 2.3–6.7° during shoulder RoM and 2.4–7.6° during ADL. The highest errors were seen during sagittal and scapular plane flexions, hair combing and eating. The reliability test included twenty subjects: female/male = 8/12, mean (SD) age 31.4 (4.9) and BMI 22.9 (1.7). The ICC(2,1) for measuring protraction ranged 0.07–0.60 during RoM and 0.27–0.69 for ADL, for upward rotation the corresponding ICC(2,1) ranged 0.01–0.64 and 0.38–0.60, and anterior tilt 0.25–0.83 and 0.25–0.62. The validity and interrater reliability of the model are task dependent, and interpretation should be made with caution. The model provides quantitative measurements for objective assessment of scapular movements and can potentially supplement the clinical examination in certain motion tasks.

Background: Spinometry is a radiation-free method to three-dimensional spine imaging that provides additional information about the functional gait patterns related to the pelvis and lower extremities. This radiation-free technology uses the surface topography of the trunk to analyze surface asymmetry and identify bony landmarks, thereby aiding the assessment of spinal deformity and supporting long-term treatment regimes. Especially reliable dynamic spinometric data for spine and pelvis are necessary to evaluate the management of non-specific back pain. Research aim: This study aims to generate reliable dynamic spinometric data for spine and pelvis parameters that can serve as reference data for future studies and clinical practice. Methods: This study assessed 366 subjects (185 females) under static and 360 subjects (181 females) under dynamic (walking on a treadmill at 3 km/h and 5 km/h) conditions. The DIERS Formetric 4Dmotion® system uses stripes of light to detect the surface topography of the spine and pelvis and identifies specific landmarks to analyze the spine during standing and walking. Results: Relevant gender effects were calculated for lordotic angle (ηp2 = 0.22) and pelvic inclination (ηp2 = 0.26). Under static conditions, female subjects showed larger values for both parameters (lordotic angle: 41.6 ± 8.60°; pelvic inclination: 25.5 ± 7.49°). Regarding speed effects, three relevant changes were observed (sagittal imbalance: ηp2 = 0.74, kyphotic angle: ηp2 = 0.13, apical deviation: ηp2 = 0.11). The most considerable changes were observed between static condition and 3 km/h, especially for sagittal imbalance and lordotic angle. For these parameters, relevant effect sizes (d > 0.8) were calculated between static and 3 km/h for males and females. Concerning clinical vertebral parameters, only lordotic angle and pelvic inclination were correlated with each other (r = 0.722). Conclusion: This study generated a gender-specific reference database of asymptomatic individuals for static and dynamic spinometry. It demonstrated that the DIERS Formetric 4Dmotion® system could capture natural changes in static and dynamic situations and catalogue functional adaptations of spino-pelvic statics at different speeds. The lordotic angle is an indirect marker of pelvic inclination, allowing spinometry to identify individuals at risk even under dynamic conditions.

Background Restrictive cardiomyopathy (RCM) is characterized by impaired diastolic function with preserved ventricular contraction. Several pathogenic variants in sarcomere genes, including TNNI3, are reported to cause Ca2+ hypersensitivity in cardiomyocytes in overexpression models; however, the pathophysiology of induced pluripotent stem cell (iPSC)‐derived cardiomyocytes specific to a patient with RCM remains unknown. Methods and Results We established an iPSC line from a pediatric patient with RCM and a heterozygous TNNI3 missense variant, c.508C>T (p.Arg170Trp; R170W). We conducted genome editing via CRISPR/Cas9 technology to establish an isogenic correction line harboring wild type TNNI3 as well as a homozygous TNNI3‐R170W. iPSCs were then differentiated to cardiomyocytes to compare their cellular physiological, structural, and transcriptomic features. Cardiomyocytes differentiated from heterozygous and homozygous TNNI3‐R170W iPSC lines demonstrated impaired diastolic function in cell motion analyses as compared with that in cardiomyocytes derived from isogenic‐corrected iPSCs and 3 independent healthy iPSC lines. The intracellular Ca2+ oscillation and immunocytochemistry of troponin I were not significantly affected in RCM‐cardiomyocytes with either heterozygous or homozygous TNNI3‐R170W. Electron microscopy showed that the myofibril and mitochondrial structures appeared to be unaffected. RNA sequencing revealed that pathways associated with cardiac muscle development and contraction, extracellular matrix‐receptor interaction, and transforming growth factor‐β were altered in RCM‐iPSC‐derived cardiomyocytes. Conclusions Patient‐specific iPSC‐derived cardiomyocytes could effectively represent the diastolic dysfunction of RCM. Myofibril structures including troponin I remained unaffected in the monolayer culture system, although gene expression profiles associated with cardiac muscle functions were altered.

Aiming at the problems of single flapping wing movement mode and low flight flexibility and stability of flapping-wing aircraft, a single-drive multi-mode flapping-wing aircraft based on the space linkage mechanism is designed. The kinematic model of the flapping-wing aircraft is established, and the driving mechanism is analyzed by Matlab and Adams co-simulation, and the kinematic characteristics of the flapping-wing aircraft is obtained by comparison. The aerodynamic model of a single-drive multi-mode flapping-wing aircraft is established. The windward resistance with periodic variation is applied to the wing, and the dynamic characteristics of the flapping-wing aircraft are analyzed. Through the kinematic and aerodynamic coupling analysis of the combined mechanism, the coupling dynamic characteristics of the flapping-wing aircraft are obtained, which provides a research basis for the flight control and performance improvement of the flapping-wing aircraft in the future.

Running is one of the most popular sports worldwide motivating many non-athletic people to start new physical activities. But especially novice runners are at risk to develop injuries as they tend to run with prejudicial posture. Hence, there has been considerable research to identify factors improving running performance. One of these factors is the correct movement of arms as a swinging pendulum during running. Based on this knowledge ergonomically shaped handgrip elements were designed to improve the posture of the shoulder-arm complex during running. The main objective of this study was the validation of the actual effectiveness on shoulder-arm posture of these handgrips. In this sense 25 adult, healthy persons without running experience were examined by motion capture analysis during running on a treadmill with and without the use of the handgrips. The focus of movement analysis was on changes of hand supination, shoulder abduction and shoulder rotation. Flexion of elbows and shoulders were not expected to change and thus, were investigated as an internal control. Significant changes were found in sense of a reduction of forearm pronation, shoulder abduction, and internal rotation of the shoulder, resulting in improved posture during running. At the same time, no significant changes were found in elbow flexion and shoulder flexion. Future studies are needed to investigate the effects of the detected improvement of arm posture on other important running parameters, such as trunk stability, movement of lower limbs, running economy, and risk of injury. These studies should also compare effects in competitive athletes, recreational runners, and novice runners.

With the recent increase in interest in machine learning and computer vision, camera-based pose estimation has emerged as a promising new technology. One of the most popular libraries for camera-based pose estimation is MediaPipe Pose due to its computational efficiency, ease of use, and the fact that it is open-source. However, little work has been performed to establish how accurate the library is and whether it is suitable for usage in, for example, physical therapy. This paper aims to provide an initial assessment of this. We find that the pose estimation is highly dependent on the camera’s viewing angle as well as the performed exercise. While high accuracy can be achieved under optimal conditions, the accuracy quickly decreases when the conditions are less favourable.

Two-stage harvesting is the main method used for the mechanized harvesting of peanuts in China, in which the pickup device is a core part of the combine harvester. In order to solve the problem of pod loss caused by “stack” and “loss picking” from peanut plants when using a traditional spring-finger cylinder pickup device, an optimal spring-finger cylinder peanut pickup mechanism was designed and its picking properties were tested. Based on the picking characteristics and picking force analysis when considering a peanut plant windrow, the ideal picking attitude and swing rule of the spring-finger were determined, and the cam slide, as the core element of the spring-finger cylinder peanut pickup device, was optimized. A mathematical model of the cam cylinder center line was established according to the swing law of the four picking stations utilizing the spring-finger. MATLAB and ADAMS were used to establish a simulation of the pickup mechanism, and kinematics and dynamics simulation analyses of the pickup mechanism were carried out. According to the design results, a prototype was constructed and a running pickup test was carried out. The peanut plant picking experiments indicated that the phenomenon of peanut plant stacking had significantly disappeared. Furthermore, through response surface analysis, the optimal working parameters of the picking device were obtained as follows: the forward speed Vm was 48.0 m/min, the rotational speed N was 50 r/min, and the ground height H was −16.8 mm. The picking rate of peanut plants was 99.21% and the pod loss rate was 1.79% under two harvesting conditions, with a peanut plant moisture content of 15% to 17%. This study provides technical support for the future design of picking devices for two-stage peanut pickup harvesters.

This study aimed to clarify the differences between the previously reported mechanisms of sports-related concussion (SRC) injuries without a loss of consciousness in contact and collision sports and the mechanisms of SRC injuries in our cases. Based on two videos of SRC injuries occurring during a men’s rhythmic gymnastics competition (three people were injured), the risk of SRC occurrence was estimated from various parameters using a multibody analysis and eight brain injury evaluation criteria. In the present study, the three SRC impacts that occurred in men’s rhythmic gymnastics showed significant characteristics in duration compared to previously reported cases in the contact sports. This suggests that the occurrence of SRC may have been caused by a different type of impact from that which causes SRC in contact sports (e.g., tackling). In addition, calculation of the strain indicating the rate of brain deformation suggested a risk of nerve swelling in all cases involving type 2 axonal injuries. Therefore, when reexamining sports-related head injuries, it is important to recognize the characteristics and mechanisms of SRC that occur in each different sport, as well as the symptoms and course of SRC after injury.

This study evaluates the effects of object weight and hand dominance on the end-point kinematics of the hand-to-mouth (withdrawal) movement in a functional reach-to-drink task for typically developing school-aged children. Using 3D motion capture, speed (average velocity and peak velocity), straightness (ratio), and smoothness (number of velocity peaks and log dimensionless jerk) of hand movements were calculated for the withdrawal motion with three different bottle weights (empty, half-filled, and full). Average velocity (550.4 ± 142.0 versus 512.1 ± 145.6 mm/s) and peak velocity (916.3 ± 234 versus 842.7 ± 198.4 mm/s) were significantly higher with the empty versus half-filled bottle and with the non-dominant (average: 543.5 ± 145.2 mm/s; peak: 896.5 ± 207 mm/s) versus dominant (average: 525.2 ± 40.7 mm/s; peak: 864.2 ± 209.2 mm/s) hand. There were no differences in straightness or smoothness. These findings indicate that increasing weight in reach-to-drink task puts greater constraints on the task. The slower movements with the dominant hand might denote better precision control than the non-dominant hand. The quantitative motion capture results show average values for the kinematic variables for a functional reach-to-drink task in a typically developing population of school-aged children with changing weights of the bottles that are relevant to a real-life scenario. These results could inform the design of individualized therapeutic interventions to improve functional upper-extremity use in children with neurodevelopmental motor disorders.

(1) Background and objectives: Running-related injuries (RRIs) are commonly attributed to improper running posture and overuse. This study aims to analyze the running motions of individuals with and without RRIs using a sensor-free method, which offers a user-friendly and straightforward approach. (2) Materials and Methods: A total of 155 runners were divided into two groups: the normal runner group (runners who had never been injured, n = 50) and the RRI group (runners who had experience at least one injury while running, n = 105). The forward head posture (FHP), trunk lean, hip rotation, horizontal movement of the center of gravity (COG), vertical movement of the COG, pelvic rotation, hip hike, and type of strike were measured for posture analysis. (3) Results: We found that the left–right balance of the pelvis and the spinal posture during running were associated with RRIs. The difference in hip hike and FHP emerged as key predictors of running-related musculoskeletal injury occurrence from our logistic regression analysis. (4) Conclusions: Identifying pathological movements in runners through running motion analysis without the use of sensors can be instrumental in the prevention and treatment of RRIs.

Back-Support Industrial Exoskeletons (BSIEs) are designed to reduce muscle effort during repetitive tasks that involve trunk bending. We recruited twelve participants to perform 30 cycles of 45° trunk bending with/without the assistance of BSIEs and with/without postural asymmetry, first without any back fatigue, and then at the medium–high level of perceived back fatigue. To study the benefits of BSIEs, the effects of being in a fatigued state were assessed by comparing the muscle demands, kinematics, and stability measures during bending, retraction, and their transition portions per cycle across the study conditions. Overall, the BSIEs caused a minimal decrease in the lower-back activity (0–1.8%), caused by the increased demands during the retraction portion. A substantial decrease in leg activity was observed (10–18%). Asymmetry increased the right-lower-back and leg demands. Medium–high fatigue caused an increase in the lower-back activity (8–12%) during bending and retraction. The BSIEs caused slower movements and improved the stability by lowering the maximum distance of the Center of Pressure (COP) during the transition portion, as well as by lowering the mean velocity of the COP during the bending/retraction portions. This controlled study demonstrated the use of a cyclic trunk flexion–extension paradigm to study the effects of BSIEs, and the outcomes can help with understanding the temporal effects of using BSIEs on physiological measures, ultimately benefiting their proper implementation.

In recent years, preoperative planning has undergone significant advancements, with a dual focus: improving the accuracy of implant placement and enhancing the prediction of functional outcomes. These breakthroughs have been made possible through the development of advanced processing methods for 3D preoperative images. These methods not only offer novel visualization techniques but can also be seamlessly integrated into computer-aided design models. Additionally, the refinement of motion capture systems has played a pivotal role in this progress. These “markerless” systems are more straightforward to implement and facilitate easier data analysis. Simultaneously, the emergence of machine learning algorithms, utilizing artificial intelligence, has enabled the amalgamation of anatomical and functional data, leading to highly personalized preoperative plans for patients. The shift in preoperative planning from 2D towards 3D, from static to dynamic, is closely linked to technological advances, which will be described in this instructional review. Finally, the concept of 4D planning, encompassing periarticular soft tissues, will be introduced as a forward-looking development in the field of orthopedic surgery.

In the field of straw recycling, a cotton straw-harvesting mechanism is an important piece of agricultural equipment. The mechanistic analysis method of the harvesting mechanism is a major focus of research and development in this field. Currently, in the mechanistic analysis of the cotton straw recycling mechanism, the kinematic and mechanical analysis of the recycling mechanism is generally the main focus. There is not a lot of research based on the quantitative analysis between different recycling mechanisms. In this study, a clamped cotton straw pulling mechanism is optimized and designed, and two different pulling structures are designed. In addition, a two-dimensional modeling and analysis method is used to establish the two-dimensional equations of motion of the two pulling mechanisms, analyze the leakage and breakage rates of the two clamping structures, predict the final pulling effect, and verify the results of the field tests. According to the analysis, the belt-clamping side has more uniform clamping stress and a larger clamping contact area than the chain-clamping side, and the tangential stress on cotton straw is smaller. Based on the field-test verification, the band-clamping side had a higher pulling net rate by an average of 19.32% and a lower missed pulling rate by an average of 6.01% than the chain-clamping side. Therefore, it was determined that the main reason for the lower pulling net rate of the chain-gripped side than that of the belt-gripped side was the higher pulling breakage rate, and the secondary reason was the high leakage pulling rate. Thus, the feasibility and accuracy of the analytical method of this study are verified.

Traditional motion analysis systems are impractical for widespread screening of non-contact anterior cruciate ligament (ACL) injury risk. The Kinect V2 has been identified as a portable and reliable alternative but was replaced by the Azure Kinect. We hypothesize that the Azure Kinect will assess drop vertical jump (DVJ) parameters associated with ACL injury risk with similar accuracy to its predecessor, the Kinect V2. Sixty-nine participants performed DVJs while being recorded by both the Azure Kinect and the Kinect V2 simultaneously. Our software analyzed the data to identify initial coronal, peak coronal, and peak sagittal knee angles. Agreement between the two systems was evaluated using the intraclass correlation coefficient (ICC). There was poor agreement between the Azure Kinect and the Kinect V2 for initial and peak coronal angles (ICC values ranging from 0.135 to 0.446), and moderate agreement for peak sagittal angles (ICC = 0.608, 0.655 for left and right knees, respectively). At this point in time, the Azure Kinect system is not a reliable successor to the Kinect V2 system for assessment of initial coronal, peak coronal, and peak sagittal angles during a DVJ, despite demonstrating superior tracking of continuous knee angles. Alternative motion analysis systems should be explored.

The aim of this study was to examine match running patterns before a hamstring muscle injury occurs during a match in male professional football players. A total of 281 male professional football players belonging to 7 teams from LaLiga were prospectively monitored over three seasons. Among these, 36 players suffered a non-contact hamstring muscle injury during an official match. The injuries were recorded by the medical staff, including the minute when the injury occurred. Running distances at different speed thresholds for 5 min and 15 min before the injury were compared to mean values of the previous 5 matches for the same time points. There were a total of 44 non-contact hamstring muscle injuries, which represents a hamstring muscle injury incidence of 3.34 injuries/1000 h of match exposure. The average time loss for these injuries was 33±28 days (range 7 to 117 days). In the 15 min prior to the injury, players ran a similar distance as in control matches ( p from 0.22 to 0.08). However, players ran a greater distance in the 5-min period before the injury than in control matches at 21.0–23.9 km/h ( p < 0.001) and at ≥ 24 km/h ( p 30.0 m at ≥ 21 km/h in a 5-min period ( p 21 km/h, compared with control matches. This suggests that a short period of unusual running increases the risk of hamstring muscle injury in professional football players.

Abstract Background With concerns about accurate diagnosis through telehealth, the Kinect sensor offers a reliable solution for movement analysis. However, there is a lack of practical research investigating the suitability of a Kinect-based system as a functional fitness assessment tool in homecare settings. Hence, the objective of this study was to evaluate the feasibility of using a Kinect-based system to assess physical function changes in the elderly. Methods The study consisted of two phases. Phase one involved 35 young healthy adults, evaluating the reliability and validity of a Kinect-based fitness evaluation compared to traditional physical examination using the intraclass correlation coefficient (ICC). Phase two involved 665 elderly subjects, examining the correlation between the Kinect-based fitness evaluation and physical examination through Pearson’s correlation coefficients. A Kinect sensor (Microsoft Xbox One Kinect V2) with customized software was employed to capture and compute the movement of joint centers. Both groups performed seven functional assessments simultaneously monitored by a physical therapist and the Kinect system. System usability and user satisfaction were assessed using the System Usability Scale (SUS) and Questionnaire for User Interface Satisfaction (QUIS), respectively. Results Kinect-based system showed overall moderate to excellent within-day reliability (ICC = 0.633-1.0) and between-day reliability (ICC = 0.686-1.0). The overall agreement between the two devices was highly correlated (r ≧ 0.7) for all functional assessment tests in young healthy adults. The Kinect-based system also showed a high correlation with physical examination for the functional assessments (r = 0.858–0.988) except functional reach (r = 0.484) and walking speed(r = 0.493). The users’ satisfaction with the system was excellent (SUS score = 84.4 ± 18.5; QUIS score = 6.5–6.7). Conclusions The reliability and validity of Kinect for assessing functional performance are generally favorable. Nonetheless, caution is advised when employing Kinect for tasks involving depth changes, such as functional reach and walking speed tests for their moderate validity. However, Kinect’s fundamental motion detection capabilities demonstrate its potential for future applications in telerehabilitation in different healthcare settings.

Background: Scapula kinematics is recognized to be a crucial variable in shoulder dysfunction. Nevertheless, quantitative scapula tracking and measurement are not part of the current clinical evaluation. The main concern is measurement accuracy. Methods: To assess the accuracy of the wearable sensor technology Showmotion a cadaver experiment was designed, allowing a direct comparison between sensors directly pinned to the scapula and superficial sensors. A measurement protocol was adopted to evaluate errors in measurement, mimicking the suggested in vivo evaluation. Sensors were simultaneously placed above (supraspinal) and below (infraspinal) the scapular spine to determine if one placement resulted in fewer errors compared to the other. Results: Mean and standard deviations of the supraspinal sensor root mean square error (RMSE) in flexion-extension movements resulted in 3.59° ± 2.36°, 4.73° ± 2.98°, and 6.26° ± 3.62° for upward-downward rotation (up-down), anterior-posterior tilt and internal-external (intra-extra) rotation, respectively, while 2.16° ± 1.21°, 2.20° ± 1.02°, and 4.46° ± 2.16° for the infraspinal sensor. In abduction-adduction movements, mean and standard deviations of the supraspinal sensor RMSE resulted in 4.26° ± 2.98°, 5.68° ± 4.22°, and 7.04° ± 4.36° for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.38° ± 1.63°, 2.47° ± 1.77°, and 4.92° ± 3.14° for the infraspinal sensor. The same behavior was confirmed in shrug movements, where 4.35° ± 3.24°, 4.63° ± 3.09°, and 5.34° ± 6.67° are mean and standard deviations of the supraspinal sensor RMSE for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.76° ± 1.87°, 2.83° ± 2.53°, and 4.68° ± 5.22° for the infraspinal sensor. Conclusion: This method of quantitative assessment of scapular motion is shown to have good accuracy and low error between the sensor measurements and actual bone movement in multiple planes of scapular motion, both over the entire range of motion and in its individual segment intervals. The decreased amount of error with the infraspinal sensor placement suggests that placement is ideal for clinical quantitative assessment of scapular motion.

The purpose of this study was to compare and examine gait parameters, hip joint angle, and lower extremity muscle activity during normal walking before and after Nordic walking (NW) intervention. Nineteen healthy male participants (age 26.3 ± 2.4 years) were included in the study. During walking, we measured gait parameters using the footprint-measuring gait analysis system. Аngular changes of the hip joint were measured with an IMU-type portable three-dimensional motion analyzer and the EMG activity of each muscle. The measurements above were performed before and after a one-hour NW training course. The hip joint angle, muscle activity, and gait parameters were compared before and after the intervention with the same participants. In gait parameters, the stride length and walking speed were significantly greater after the intervention, while the cadence decreased significantly. Both hip flexion and extension angles were significantly greater after the intervention. In terms of muscle activity, the rectus abdominis, the tibialis anterior, and the gastrocnemius were very different after the intervention. According to previous reports, employing a large stride length during NW would affect the normal gait after the training. The use of the Nordic pole may have stimulated a substantial forward movement in the lower extremities using the large range of motion of the hip joints. The benefits of NW include enhanced forward propulsion during gait and additional stability during the stance phase due to the greater support surface provided by the poles.