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This study aimed to clarify the differences in muscular coordination during butterfly swimming between high- and low-performance swimmers using muscle synergy analysis. Eight female competitive swimmers and 8 female recreational swimmers participated in this study. The participants swam a 25-m butterfly stroke with maximum effort. Surface electromyography was measured from 12 muscles and muscle synergy analysis was performed from the data using nonnegative matrix factorization algorithms. From the results of the muscle synergy analysis, 4 synergies were extracted from both groups. Synergies 1 and 2 were characterized by coactivation of the upper and lower limb muscles in the recreational swimmers, whereas only synergy 1 was characterized by this in the competitive swimmers. Synergy 3 was involved in arm recovery in both groups. Synergy 4 was only involved in the downward kick in the competitive swimmers. From these results, it can be concluded that muscle synergies with combined coordination of upper and lower limb muscles were extracted more in the recreational swimmers and that the competitive swimmers controlled the downward kick with an independent synergy and that the adjustment of the timing of the downward kick may be an important factor for the efficient performance of butterfly swimming. [ABSTRACT FROM AUTHOR]

Altering baseball pitching mechanics affects both performance and the risk of injury. The purpose of this study is to investigate the relationships of shoulder external over internal rotation ratio (SEIR) and other shoulder rotational properties during physical exam and biomechanics of pitching for 177 collegiate baseball pitchers. The shoulder range of motion was quantitatively measured using a custom-made wireless device. Pitching motion data were collected at 240 Hz, and a custom program was created to calculate the throwing arm motion and loading during baseball pitching. Linear regression and analysis of variance tests were performed to investigate the relationships between the shoulder physical exam outcomes and throwing arm biomechanics. SEIR had significant correlations with shoulder horizontal adduction angle at foot contact, maximum shoulder external rotation angle, maximum shoulder linear velocity, and elbow angle at ball release. SEIR groups had significant differences in shoulder proximal force, adduction torque, internal rotation torque, and horizontal adduction torque, and in elbow medial force and varus torque. Glenohumeral internal rotation deficit and total rotational motion deficit had no relationships with throwing arm motions or joint loadings. Shoulder health should be monitored to improve understanding of pitching mechanics in collegiate baseball pitchers. [ABSTRACT FROM AUTHOR]

Foot stance and club type's relationship with lead knee joint biomechanics and possible involvement with injury incidences in amateur golfers have not been evaluated. This study included 16 male right-handed amateur golfers who performed golf swings with 2 different foot stances (straight and open) using 4 different club types (driver, 3 iron, 6 iron, and 9 iron) while standing on 2 force plates in a motion capture laboratory. A custom program calculated the kinematics and kinetics of the lead knee. Overall, the open stance reduced most translations, rotations, forces, and torques of the lead knee in all 4 club types when compared with the straight stance. The open stance reduced the rotation motion (−28%), compressive force (−5%), and rotation torque (−9%) when compared with the straight stance, which are the highest contributors to grinding of cartilage. The driver club had significantly larger values in most translations, rotations, forces, and torques when compared among the 4 club types. The open stance reduced the rotation motion, compressive force, and rotation torque in the lead knee joint compared with the straight stance. Lead knee joint biomechanics should be monitored to reduce injury in amateur golfers. [ABSTRACT FROM AUTHOR]

Deficits in movement patterns during cutting while running might place soccer players at risk of injury. The objective was to compare joint angles and intersegment coordination between sexes and ages during an unanticipated side-step cutting task in soccer players. This cross-sectional study recruited 11 male (four adolescents and seven adults) and 10 female (six adolescents and four adults) soccer players. Three-dimensional motion capture was used to measure lower-extremity joint and segment angles as participants performed an unanticipated cutting task. Hierarchical linear models examined relationships between joint angle characteristics with age and sex. Continuous relative phase was used to quantify intersegment coordination amplitude and variability. These values were compared between age and sex groups using analysis of covariance. Adult males had greater hip flexion angle excursions than adolescent males, while adult females had smaller excursions than adolescent females (p = .011). Females had smaller changes in hip flexion angles (p = .045), greater hip adduction angles (p = .043). and greater ankle eversion angles (p =.009) than males. Adolescents had greater hip internal rotation (p = .044) and knee flexion (p = .033) angles than adults, but smaller changes in knee flexion angles at precontact compared with stance/foot off (p < .001). For intersegment coordination, females were more out-of-phase than males in the foot/shank segment in the sagittal plane. There were no differences in intersegment coordination variability between groups. Differences in joint motion during an unanticipated cutting task were present between age groups and sexes. Injury prevention programs or training programs may be able target specific deficits to lower injury risk and improve performance. [ABSTRACT FROM AUTHOR]

Instability is one of the major failure modes of long span arch bridges, and its possibility of occurrence will be increased as triggered by earthquake excitations. However, the randomness of each ground motion causes the difficulty in achieving a reliable assessment of the safety of the bridges in regard to its stability issue based on certain time history analysis. Therefore, a failure probability-based instability evaluation method and corresponding instability damage index are proposed in this study to solve this problem, converting the deterministic analysis of a ground motion into a probability analysis of a group of random ground motions. The results find that the input direction, the velocity pulse and the pulse period of the ground motion have a significant impact on the stability of the bridge, while seismic moment and PGV/PGA ratio do not. The fragility curves show that the bridge has more than 60% probability of slight instability when input PGA reaches 0.2 g, 50% probability of moderate instability when input PGA reaches 0.6 g, and 20% probability of collapse when input PGA reaches 1.0 g. Moreover, when the PGA approaches 1.0 g, it is discovered that the velocity pulse and the pulse period can increase the chance of the occurrence of bridge instability by 20%–30%. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Level of Evidence In this study, prospective data were used to evaluate whether the early peak knee abduction moment waveform is associated with the risk of anterior cruciate ligament (ACL) injury.Biomechanical data from 84 athletes who participated in the study as adolescents were analysed after cross‐referencing national health registry data to confirm ACL reconstruction in the subsequent years. The knee abduction moment waveform shape was obtained with cluster analysis for the first 100 ms of a cutting manoeuvre (1776 trials in total) and classified as either containing an early peak knee abduction moment or not, and the odds ratio for later ACL injury was then calculated. Additionally, discrete kinematic and kinetic variables were extracted, and tested against the risk of ACL injury using mixed model logistic regression.Of 84 athletes, 8 (all female) sustained a total of 13 ACL injuries in the years after motion analysis data collection. Six clusters of knee abduction moment waveform shapes were identified. Two clusters containing 446 trials were classified as an early peak knee abduction waveform. This waveform was associated with a 7.2‐fold increase in the risk of ACL injury (95% confidence interval: 2.4–24.6; p < 0.001). Of the kinematic and kinetic variables tested, only the knee abduction angle at initial contact was associated with an increased risk of ACL injury (p < 0.001).This is the first study to confirm the association between the early peak knee abduction moment waveform and the risk of ACL injury. Using waveforms, instead of discrete peak values of the knee abduction moment, may better represent risky movement patterns. Replicating these findings in a larger cohort will support the use of this method to screen athletes for risk and guide targeted preventive interventions and their efficacy.Level II. [ABSTRACT FROM AUTHOR]

Despite improvements in implant design, surgical techniques and assistive technologies for total knee arthroplasty (TKA), anterior knee pain (AKP) remains frequently reported, even by satisfied patients. This persistent problem calls for better understanding and management of the patellofemoral or anterior compartment during surgery, just as the techniques and strategies deployed to optimize the flexion and extension spaces through personalized alignment, bone cuts and ligament balancing. Assistive technologies such as navigation and robotics provide new tools to manage this ‘third space’ through precise pre‐operative planning and dynamic intra‐operative assessment. Such endeavors must start with clear definitions of the ‘third space’, how it should be measured, what constitutes its ‘safe zone’, and how it affects outcomes. There are yet no established methods to evaluate the patellofemoral compartment, and no clear thresholds to define over‐ or under‐stuffing. Static assessment using lateral radiographs provides a limited understanding and depends considerably on flexion angle, while dynamic evaluation at multiple flexion angles or using intra‐operative computer or robotic‐assistance enables a broader perspective and solutions to manage patellar tracking and anterior offset. Future studies should investigate the impact of variations in anterior offset in TKA, define its safe zone, and understand the effects of of thresholds for over‐ or under‐stuffing. Experimental methods such as in‐vivo motion analysis and force sensors could elucidate the influence of anterior offset on flexion and extension biomechanics. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) motion analysis (MA) techniques are progressively being used in biomechanics research and for clinical applications to assess the risk of injuries. A marker-based 3D MA protocol has been developed to measure the upper and lower extremity (UE and LE) joints' active and passive ranges of motion (AROM and PROM) in children. The joints that were included in this protocol are shoulder, elbow, wrist, hip, knee and ankle. The anatomical joint coordinate systems (JCS) have been defined for the upper and lower extremities to standardize reporting. A marker placement model was defined according to the International Society of Biomechanics (ISB) recommendations and used to develop the protocol. The proposed movements will be captured and analyzed using the Motion Analysis Corporations 3D MA system integrated with Cortex software. The movements adopted in this study have been selected from various sources to incorporate all joint rotations while ensuring the isolation of each joint motion during the movements. It is recommended that future studies utilize this protocol to draw a relationship between the joints' range of motion (ROM) and the adjacent segments characteristics, i.e., segment length, joint stiffness, etc. [ABSTRACT FROM AUTHOR]

Introduction: Osteogenesis imperfecta (OI) is a hereditary disorder primarily caused by mutations in type I collagen genes, resulting in bone fragility, deformities, and functional limitations. Studies on upper extremity deformities and associated functional impairments in OI are limited. This cross-sectional study aimed to evaluate upper extremity deformities and functional outcomes in OI. Methods: We included patients regardless of their OI subtypes with a minimum age of 7 years. Radiographic analysis of radial head dislocation, ossification of the interosseous membrane, and/or radioulnar synostosis of the forearm were performed, and deformity was categorized as mild, moderate, or severe. Clinical evaluation was performed using the Quick Disabilities of Arm, Shoulder, and Hand (qDASH) questionnaire and shoulder-elbow-wrist range of motion (ROM). Three-dimensional motion analysis of the upper limb was conducted using the Southampton Hand Assessment Procedure (SHAP). The SHAP quantifies execution time through the Linear Index of Function (LIF) and assesses the underlying joint kinematics using the Arm Profile Score (APS). Additionally, the maximum active Range of Motion (aRoM) was measured. Results: Fourteen patients aged 8 to 73 were included. Radiographic findings revealed diverse deformities, including radial head dislocation, interosseous membrane ossification, and radioulnar synostosis. Six patients had mild, six moderate, and two severe deformities of the upper extremity. Severe deformities and radial head dislocation correlated with compromised ROM and worse qDASH scores. The qDASH score ranged from 0 to 37.5 (mean 11.7). APS was increased, and LIF was reduced in OI-affected persons compared with non-affected peers. APS and LIF also varied depending on the severity of bony deformities. aRoM was remarkably reduced for pro-supination. Conclusion: Patients with OI showed variable functional impairment from almost none to severe during daily life activities, mainly depending on the magnitude of deformity in the upper extremity. Larger multicenter studies are needed to confirm the results of this heterogeneous cohort. Level of evidence: Retrospective clinical study; Level IV. [ABSTRACT FROM AUTHOR]

Over the past decades, tremendous technological advances have emerged in human motion analysis (HMA). How has technology for analysing human motion evolved over the past decades, and what clinical applications has it enabled? The literature on HMA has been extensively reviewed, focusing on three main approaches: Fully-Instrumented Gait Analysis (FGA), Wearable Sensor Analysis (WSA), and Deep-Learning Video Analysis (DVA), considering both technical and clinical aspects. FGA techniques relying on data collected using stereophotogrammetric systems, force plates, and electromyographic sensors have been dramatically improved providing highly accurate estimates of the biomechanics of motion. WSA techniques have been developed with the advances in data collection at home and in community settings. DVA techniques have emerged through artificial intelligence, which has marked the last decade. Some authors have considered WSA and DVA techniques as alternatives to "traditional" HMA techniques. They have suggested that WSA and DVA techniques are destined to replace FGA. We argue that FGA, WSA, and DVA complement each other and hence should be accounted as "synergistic" in the context of modern HMA and its clinical applications. We point out that DVA techniques are especially attractive as screening techniques, WSA methods enable data collection in the home and community for extensive periods of time, and FGA does maintain superior accuracy and should be the preferred technique when a complete and highly accurate biomechanical data is required. Accordingly, we envision that future clinical applications of HMA would favour screening patients using DVA in the outpatient setting. If deemed clinically appropriate, then WSA would be used to collect data in the home and community to derive relevant information. If accurate kinetic data is needed, then patients should be referred to specialized centres where an FGA system is available, together with medical imaging and thorough clinical assessments. • Gait analysis by stereophotogrammetry provides highly accurate biomechanics of motion. • Wearable sensors enable ecological data collection at home and in community setting. • Deep-learning video analysis can perform motion capture without instruments on subjects. • Several authors suggest more modern technologies shall replace traditional gait analysis. • We argue that these three technologies complement each other and shall be "synergistic". [ABSTRACT FROM AUTHOR]

State-of-the-art participant-specific finite element models require advanced medical imaging to quantify bone geometry and density distribution; access to and cost of imaging is prohibitive to the use of this approach. Statistical appearance models may enable estimation of participants' geometry and density in the absence of medical imaging. The purpose of this study was to: (1) quantify errors associated with predicting tibia-fibula geometry and density distribution from skin-mounted landmarks using a statistical appearance model and (2) quantify how those errors propagate to finite element-calculated bone strain. Participant-informed models of the tibia and fibula were generated for thirty participants from height and sex and from twelve skin-mounted landmarks using a statistical appearance model. Participant-specific running loads, calculated using gait data and a musculoskeletal model, were applied to participant-informed and CT-based models to predict bone strain using the finite element method. Participant-informed meshes illustrated median geometry and density distribution errors of 4.39–5.17 mm and 0.116–0.142 g/cm3, respectively, resulting in large errors in strain distribution (median RMSE = 476–492 με), peak strain (limits of agreement =±27–34%), and strained volume (limits of agreement =±104–202%). These findings indicate that neither skin-mounted landmark nor height and sex-based predictions could adequately approximate CT-derived participant-specific geometry, density distribution, or finite element-predicted bone strain and therefore should not be used for analyses comparing between groups or individuals. [ABSTRACT FROM AUTHOR]

Inspired by buckle-induced structural deformation, a new type of tensegrity robot using bending bars is proposed. First, a combination of numerical calculation and the finite-element simulation method was adopted to determine the influence of geometric parameters on equivalent stiffness, and the basic configuration parameters were determined. Then, the tensegrity dynamical model and the ground contact model were established using a nonlinear finite-element method, and four rolling gaits of the robot were realized by driving diagonal cables. Finally, an experimental prototype of the bending bar tensegrity robot was built for rolling gait experiments. The results show that the experimental rolling motion is in good agreement with the theoretical model. Through continuous curve path rolling, the minimum turning radius of the robot was determined, and the motion mode of the prismatic tensegrity robot was enriched. Practical Applications: Tensegrity structure is a self-balancing system composed of compression bars and tension cables, which has aroused numerous scholars' research interest in civil architecture, mechanical engineering, aerospace, biomedical, and other fields. The results cover model design, form-finding analysis, static equilibrium stability analysis, optimization design, dynamic response analysis, and so on. In fact, when the tensegrity mechanism is applied to a mobile robot, a change in shape can be achieved by shortening some cables with the actuator, so the system's stiffness contradicts the ability to deform. The focus of this work is to propose a new type of bending bar design that can replace the spring to meet the needs of large deformation and avoid weakening the structure's overall stiffness. This design realizes the rolling motion mode of the robot and can be applied to the motion mode of other prismatic tensegrity robots. [ABSTRACT FROM AUTHOR]

Human motion prediction in various motion capture applications, e.g., optical and inertial, is challenging because of the complexity of human motion sequences. Current studies on this issue have insufficient analysis on the latent motion information in a given motion sequence, such as motion trends, transient changes, and temporal evolution. Meanwhile, methods using simple graph convolution networks suffer from over-smoothing, causing the predicted poses staying invariant in long-term prediction. To address these challenges, we propose a multi-feature-based orthogonal graph convolution network (MFOGCN), where the multi-feature extraction consists of two key modules: (1) hybrid spectral transform, which captures local transient features and global motion trends of motion sequences by discrete wavelet transform while considering temporal smoothing between human joints and (2) mask-aware multiple attention, with sliding time windows to extract motion sequence feature representations from historical multiple subsequences, refining the correlation between adjacent poses while obtaining global dependencies between sequences. In addition, we propose orthogonal graph convolution and orthogonal loss for the prediction network, which help to stabilize the feature transformation of the graph convolution to resolve the over-smoothing issue. An extensive evaluation on the Human 3.6M, AMASS and 3DPW datasets has been conducted, showing reliable effectiveness of the proposed MFOGCN that outperforms other approaches. [ABSTRACT FROM AUTHOR]

The bipolar technique is a flaking strategy that has been identified from 3.3 Ma until the twentieth century, with no geographical or chronological homogeneous distribution. It is represented by the intentional contact of an active percussive element against a core rested on an anvil. This tool composite has been described by some researchers as a sign of low-skill of hominins, unable to perform successfully free-hand flaking or for flaking low-quality raw materials. Based on this premise, our research focused on the following question: Are there any quantitative and qualitative differences in terms of both kinematic parameters and technical skills between knappers with different levels of expertise when flaking using the bipolar technique? To get an answer, we developed a systematic experimental program with 12 volunteer participants with different levels of expertise. Then, to assess potential quantifiable differences and to understand the mechanics of bipolar technology, we did a video motion analysis based on kinematic parameters (including position, velocity, acceleration, and kinetic energy of the hammerstone). In addition, we performed a technological analysis of the experimental lithic assemblages to assess the technological differences between knappers based on their levels of expertise. In kinematic parameters, both statistical analysis and observations from the experiment clearly show that there are differences between the levels of expertise in this technique. Intermediate knappers have been observed to apply more velocity and kinetic energy than experts and novices. Also, differences were observed in the flaking strategies. Expert knappers show a longer reduction sequence, while intermediates show shorter one. Moreover, some of the novice knappers did not even obtain a single flake. The results of our experiment stress the complexity of bipolar flaking and that previous assumptions about it might be reconsidered, especially in terms of reconsidering the negative connotations attributed to this flaking technique. [ABSTRACT FROM AUTHOR]

Traditional 3D motion analysis typically considers the spine as a rigid entity. Nevertheless, previous single-joint models have proven inadequate in evaluating the movement across different spinal segments in patients with idiopathic scoliosis (IS). Scoliosis significantly impairs movement functions, especially during activities such as ascending and descending stairs. There is a lack of research on the patterns of stair movement specifically for patients with IS. This study aims to investigate trunk kinematics in college students with IS during stair ascent and descent tasks. A total of 56 participants, 28 with IS and 28 with healthy controls, were recruited for this case-control study. The trunk movements were analyzed using a motion analysis system that incorporated a multisegment spine model. Understanding the multi-segment spine kinematics during stair tasks can contribute to the development of effective rehabilitation programs for individuals with IS. Case-control study. Twenty-eight IS and 28 controls. Cobb angle, spinal curvature, spinal active range of motion (ROM), Kinematics. The Qualisys system (Gothenburg, Sweden) was utilized in this study with a sampling frequency of 150 Hz. It recorded the kinematics in the thoracic, lumbar, thoracic cage, and pelvis while ascending and descending stairs for both the 28 IS individuals and the 28 control participants. Additionally, clinical parameters such as the Cobb angle, curvature of the spine, spinal range of motion (ROM), and other relevant factors were concurrently assessed among the subjects. Project supported by the National Natural Science Foundation of China (Grant No. 82205306). The authors declare no conflict of interest in preparing this article. The findings of this study revealed that IS individuals exhibited reduced kyphotic curvature in the sagittal plane (p<.05) when compared to the control group. In contrast, these IS patients displayed greater coronal curvature (Cobb angle) in the frontal plane and a more substantial difference in thoracic side bending range of motion in comparison to the control group (p.05). Moreover, during the ascending stair activity, IS patients showed reduced thoracic cage flexion-extension range of motion (p<.05), while displaying increased lumbar rotation range of motion and anterior-posterior pelvic tilt range of motion (p<.05) in contrast to the control group. Notably, the kinematic analysis during the descent of stairs indicated that IS patients exhibited a larger range of motion in thoracic flexion-extension, thoracic side bending, thoracic cage side bending, thoracic rotation, and thoracic cage rotation when compared to the control group (p<.05). The results showed significant differences in trunk kinematics between the two groups during both stair ascent and descent tasks. The utilization of the "multisegment spine model" facilitates the acquisition of motion information across multiple segments of the spine in patients diagnosed with IS, effectively enhancing the assessment outcomes derived from imaging information. The three-dimensional structural deformity in the trunk affects both static and dynamic activity patterns. In different activity states, IS patients demonstrate stiff movements in certain segments while experiencing compensatory instability in others. In the future, clinical rehabilitation programs for IS should prioritize stair-related activity training. [ABSTRACT FROM AUTHOR]

Shoulder instability (SI) is a complex impairment, and identifying biomarkers that differentiate subgroups is challenging. Children and adolescents with SI (irrespective of etiology) have differences in their movement and muscle activity profiles compared to age- and sex-matched controls (2-tailed). There are limited fundamental movement and muscle activity data for identifying different mechanisms for SI in children and adolescents that can inform subgrouping and treatment allocation. Young people between 8 and 18 years were recruited into 2 groups of SI and age- and sex-matched controls (CG). All forms of SI were included, and young people with coexisting neurologic pathologies or deficits were excluded. Participants attended a single session and carried out 4 unweighted and 3 weighted tasks in which their movements and muscle activity was measured using 3-dimensional (3D) movement analysis and surface electromyography (sEMG). Statistical parametric mapping was used to identify between-group differences. Data were collected for 30 young people (15 SI [6 male, 9 female] and 15 CG [8 male, 7 female]). The mean (standard deviation) age of the participants was 13.6 years (3.0). The SI group demonstrated consistently more protracted and elevated sternoclavicular joint positions during all movements. Normalized muscle activity in latissimus dorsi was lower in the SI group and had the most statistically significant differences across all movements. Where differences were identified, the SI group also had increased normalized activity of their middle trapezius, posterior deltoid, and biceps muscles but decreased activity of their latissimus dorsi, triceps and anterior deltoid muscles compared with the CG group. No statistically significant differences were found for the pectoralis major across any movements. Weighted tasks produced fewer differences in muscle activity patterns compared with unweighted tasks. Young people with SI may adapt their movements to minimize glenohumeral joint instability. This was demonstrated by reduced variability in acromioclavicular and sternoclavicular joint angles, adoption of different movement strategies across the same joints, and increased activity of the scapular stabilizing muscles, despite achieving similar arm positions to the CG. Young people with SI demonstrated consistent differences in their muscle activity and movement patterns. Consistently observed differences at the shoulder girdle included increased sternoclavicular protraction and elevation accompanied by increased normalized activity of the posterior scapula–stabilizing muscles. Existing methods of measurement may be used to inform clinical decision making; however, further work is needed to evaluate the prognostic and clinical utility of derived 3D and sEMG data for informing decision making within SI. [ABSTRACT FROM AUTHOR]

During an archery competition, archers frequently fail to correctly adjust their bow's sight so that their arrow groups are centred on the target. Arrows are shot in ends of three or six, depending on the phase of the competition, and consequently each end provides very limited data on which to make sight adjustments, although at the conclusion of the competition it is usually obvious if an archer has succeeded in the task or not. This paper considers three sight optimisation processes with a view to minimise score loss both in ranking rounds and in matches. It is shown that archers should take a more aggressive rather than a less aggressive approach to sight movements, especially for the first end. Each sight adjustment process can be implemented using a simple look-up table. [ABSTRACT FROM AUTHOR]

The quantitative relationship between kicking motion and ball behaviour can be easily explained by detecting the impact point and foot posture. In previous studies, the impact point of a kicking foot was difficult to capture using visual tracking. Thus, a virtual surface modelling technique was applied in this study to clarify the differences in the three-dimensional foot speed, impact point and foot posture between straight, curve, and knuckle kicks in soccer, as well as the relationship between the kick motion and ball rotation. An optical three-dimensional motion capture system (VICON) was used to record the kicking motion. The impact points of the straight, curve, and knuckle kicks were found to be centrally located in the instep area, at a lower (more downwards) inside area, and at the medial area between the instep and inside areas of the kicking foot, respectively. Moreover, an impact with a greater 'swing vector deviation angle (relative to the direction from the impact point to the centre of gravity of the ball)' is necessary for ball rotation. The impact point detection method employed in this study can be applied to other ball impact estimations beyond soccer kicks. [ABSTRACT FROM AUTHOR]

The coefficient of friction (COF) is usually calculated from a force ratio or a translational velocity ratio. We developed a new method for calculating the COF between fingers and a thrown ball from the spin parameter (angular over translational velocity). We used triad data obtained from a motion analysis system. We rigidified the triad data with a new method by force-fitting a master triangle (obtained from average side lengths) to each triad, where the three distances between each pair of corresponding vertices are three virtual forces that are in force and moment equilibrium. We also applied a low-pass filter to the data. The following data were calculated: helical axis between two consecutive master triangles, angular velocity, translational velocity, and COF. We applied this method to cricket ball deliveries (finger-spin topspin Ft, finger-spin backspin Fb, wrist-spin topspin Wt, wrist-spin backspin Wb). The standard deviations of the triad side lengths were smaller without than with low-pass filter. The COF showed smaller interquartile and total ranges when force fitting the raw data than when force-fitting the filtered data; or filtered data without force fitting; or neither force-fitting nor filtering. The delivery finger-spin backspin exhibited the smallest COF, whereas wrist-spin backspin had the highest. Finger-spin deliveries had a smaller COF than wrist-spin ones. There was no significant difference between topspin and backspin in terms of the COF. Deliveries with the palm pointing medially (Ft, Wb) had a greater COF than deliveries with the palm pointing laterally (Fb, Wt). In conclusion, the force-fitting method was superior compared to low-pass filtering with the latter worsening the data because of filtering along the time axis rather than spatially. The COF imparted on cricket ball led to a new classification system of deliveries and to a proposal for a new bowling strategy. [ABSTRACT FROM AUTHOR]

Introduction: Alterations of scapular kinematics are generically reported as scapular dyskinesis (SD), and are a nonspecific response to various shoulder pathologies. The most widely used classification is Kibler's (K), which is, however, characterized by poor sensitivity. To overcome this limit, using a 3D motion analysis system, we identified a specific pattern for each type of SD according to Kibler. Materials and methods: We analyzed 34 patients with a total of 68 shoulders who came to our observation for shoulder pain. All patients underwent clinical examination, video-recording and motion analysis with SHoW Motion 3D kinematic tracking system (SM). Three independent observers classified SD into K types I, II and III. Only patients with concordant classification among the 3 operators were studied to identify a characteristic graphic pattern by type of SD. Results: Typical patterns emerged from the examination with SM. K. type 1 consists of decreased or reversed posterior tilt and increased protraction in flexion–extension (FE) in early degrees of motion. K. type 2 consists of increased protraction and marked reversal of lateral rotation in abduction–adduction (Ab–Ad) in early degrees of movement. K. type 3 has been subdivided into two subgroups: K. type 3-A, composed of patients with massive rotator cuff lesions, shows an increase in all scapular movements in both FE and Ab–Ad. K. type 3-B, composed of patients with scapular stiffness and/or impingement, presents a slight increase in posterior tilt and lateral rotation in the final grades of FE and Ab–Ad. Conclusions: The SM system allows reproducible dynamic analyses with low intra- and intra- operator variability. In our study, we demonstrated its applicability in the classification of SD. It also provides an objective and quantitative assessment of motor pattern alteration that is essential in the follow-up of patients to evaluate the effectiveness of rehabilitation and/or surgical treatment. Level of Evidence 3: According to "The Oxford 2011 Levels of Evidence". [ABSTRACT FROM AUTHOR]

The production of triceps surae plantarflexion moment is complex in that the Achilles tendon moment arm affects the Achilles tendon force by determining the muscle length change and shortening velocity during ankle rotation. In addition, there is evidence for associations between the sizes of muscles and their moment arm at the joints they span. These relationships between muscle architecture and tendon moment arm ultimately affect the muscle's force generating capacity and are thus important for understanding the roles played by muscles in producing locomotion. The purpose of this study was to investigate in vivo the relationship between architecture of two plantarflexors and the Achilles tendon moment arm in a healthy adult population. Ultrasound-based measurements were made of the architecture (fascicle length, muscle volume, physiological cross-sectional area, and anatomical cross-sectional area) of the lateral and medial gastrocnemius and the Achilles tendon moment arm was assessed using a technique that combined ultrasound imaging and motion analysis. Positive correlations were observed between the length (r = 0.499, p = 0.049) and size variables (muscle volume r = 0.621, p = 0.010; ACSA r = 0.536, p = 0.032) of the lateral gastrocnemius and the Achilles tendon moment arm, but correlations were only observed for size variables (muscle volume r = 0.638, p = 0.008; PCSA r = 0.525, p = 0.037; ACSA r = 0.544, p = 0.029), and not the length, of the medial gastrocnemius. These findings suggest lateral gastrocnemius adapts to moment arms to maintain force production throughout the range of motion across individuals, while the medial gastrocnemius does not and is thus better suited for static force generation. [ABSTRACT FROM AUTHOR]

In order to investigate the applicability of the ground motion generated by different methods in the seismic study of high-speed railways, this paper presents a multiple comparative analysis of the ground motion produced by the ground motion prediction equation method (GMPE) and the physically-based seismic simulation method (PBS), taking the Chi-Chi earthquake as an example. First, the ground motions of typical stations were obtained by GMPE and PBS methods and compared with the original seismic records. It is found that the PGAs of the simulated ground motions are closer to the original seismic records, and the median value of the PGAs of the ground motions selected by the GMPE method is slightly larger. There are differences between the two ground motion acceleration response spectra and the original seismic record, but there are also partially valid intervals. After that, the PBS ground motion (PBS-GM), GMPE ground motion (GMPE-GM), and original seismic record (Oril-SR) were inputted into the High-Speed Railway Track Bridge System (HSRTBS) for the dynamic history analysis, respectively. It was found that the PBS-GM overestimated the dynamic response of the HSRTBS at locations closer to the epicenter and underestimated it at locations farther away, but the error was small. In contrast, the GMPE-GM accurately estimates the dynamic response of the HSRTBS at locations moderately close to the epicenter and overestimates it at locations closer to the epicenter but with flat topography. In summary, the PBS-GM has a reliability that is not inferior to that of the GMPE-GM. [ABSTRACT FROM AUTHOR]

Introduction: When 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. Methods: Fourteen 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 discussion: The 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. [ABSTRACT FROM AUTHOR]

Motion analysis has played a crucial role in providing gait analysis for prosthetic users. Understanding kinematics in motion analysis allows for the evaluation of the effects of prostheses and the development of a prosthetic component design that aids in walking within the community. However, there are currently limited open datasets available to study the locomotion of individuals using transtibial prostheses, and most research studies involve a limited number of participants. This dataset shows 30 transtibial prosthesis users walking comfortably on a 10-meter walkway inside a laboratory. We offer a set of joint ankles obtained from the inertial measurement unit (IMU) signals in CSV file format. We also provide the optical motion capture (OMC) system's raw trajectory marker data in C3D file format and joint angle in CSV file format. This open dataset will provide resources for professionals interested in amputee gait for research in amputee gait detection and tracking algorithms. Moreover, the data will be the control data for comparison in developing advanced prosthetic components. [ABSTRACT FROM AUTHOR]

The gluteus medius (GM) plays an important role in stabilizing the knee and preventing injury. This study aimed to determine the immediate effects of weight-bearing gluteus medius exercises on lower-extremity muscle function and dynamic knee valgus. Eighteen healthy adults (nine each of both sexes) performed three types of weight-bearing gluteus medius exercises (standing, mini-squat, and dead-lift), and a range of kinematic variables were tested in triplicate. Weight-supporting GM exercise consisted of three sets of 15 repetitions of the lateral band walk. The Y-balance test (YBT) and vertical single-leg jump were used as indicators of muscle function in the lower limbs. We used a video analyzer to film the dynamic knee valgus and performed a YBT for the supporting leg and landing leg following a jump. The height of the single-leg vertical jump and the posterolateral and total YBT scores were significantly higher in the dead-lift posture than in the standing and mini-squat postures. Motion analysis of the dead-lifts revealed high hip flexion on the supporting leg in the posterolateral direction, as determined by the YBT, with low levels of internal hip rotation on the landing leg during the one-leg vertical jump. As an immediate effect of gluteus medius exercise, the dead-lift posture facilitated single-leg vertical jump, posterolateral balance, and reduced dynamic knee valgus. [ABSTRACT FROM AUTHOR]

Motion style transfer, which aims to transfer the style from a source motion to the target while keeping its content, has recently gained considerable attention. Some existing works have shown promising results but required labeled data for supervised training, limiting their applicability. In this paper, we present a novel self-supervised learning method for motion style transfer. Specifically, we cast the problem into a contrastive learning framework, which disentangles the human motion representation into a content code and a style code, and the result can be generated by compositing the style code of source motion and the content code of target motion. To encourage better code disentanglement and composition, we investigate InfoNCE loss and Triplet loss in a self-supervised manner. This framework aims at generating reasonable motions while guaranteeing the disentanglement of the latent codes. Comprehensive experiments have been conducted over the benchmark datasets and demonstrated our superior performance over state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Introduction: Stereotype threat can lead older adults to perceive their experiences in a biased manner, giving rise to interfering thoughts and negative emotions that generate stress and anxiety. Negative beliefs about aging may serve as an additional factor that increases the need for attentional demand, potentially resulting in a performance level below their actual capabilities. In the present study, we asked whether negative aging stereotypes influence a dynamic balance task and explored the means to counteract them in healthy elderly participants. Methods: The performance of balance was compared in two groups of participants aged 65 to 75 years (n = 22) under stereotype threat or reducedthreat situation. Balance abilities were tested under dynamic conditions, requiring participants to maintain balance on a moving platform and using a gradient of difficulty (with eyes open or closed, without or with foam). Postural performance was evaluated by means of posturographic evaluation of the center of pressure displacement and motion analysis. Additionally, we investigated the effects of stereotype threat on a preferred walking speed task and on the Timed Up and Go (TUG) test. Results: Participants under stereotype threat showed poorer balance, particularly in challenging conditions (eyes closed, on foam), with less effective body segments stabilization. Their postural stabilization on foam was worse compared to a solid surface. Conversely, those in the reduced threat condition maintained better body segment stabilization across all conditions, indicating consistent postural control regardless of the presence of foam. Stereotype threat did not affect preferred walking speed or the time to complete the "Time Up and Go" test. Discussion-conclusion: This study provides the first description of age-based stereotype threat effects on a dynamic balance task and how to counteract them in healthy older adults. We suggest that the decrease in postural performance observed in participants exposed to stereotype threat can be attributed to a split in attentional focus between negative intrusive thoughts and the attention needed for maintaining balance. These findings open new perspectives on how to overcome negative expectations when evaluating and training physical abilities, thereby contributing to fall prevention among older adults. [ABSTRACT FROM AUTHOR]

Running is the basis of many sports and has highly beneficial effects on health. To increase the understanding of running, DSPro® insoles were developed to collect running parameters during tasks. However, no validation has been carried out for running gait analysis. The aims of this study were to assess the test–retest reliability and criterion validity of running gait parameters from DSPro® insoles compared to a motion-capture system. Equipped with DSPro® insoles, a running gait analysis was performed on 30 healthy participants during overground and treadmill running using a motion-capture system. Using an intraclass correlation coefficient (ICC), the criterion validity and test–retest reliability of spatiotemporal parameters were calculated. The test–retest reliability shows moderate to excellent ICC values (ICC > 0.50) except for propulsion time during overground running at a fast speed with the motion-capture system. The criterion validity highlights a validation of running parameters regardless of speeds (ICC > 0.70). This present study validates the good criterion validity and test–retest reliability of DSPro® insoles for measuring spatiotemporal running gait parameters. Without the constraints of a 3D motion-capture system, such insoles seem to be helpful and relevant for improving the care management of active patients or following running performance in sports contexts. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The utilization of inertial measurement units as wearable sensors is proliferating across various domains, such as health care, sports, and rehabilitation. This expansion has produced a market of devices tailored to accommodate very specific ranges of operational demands. Simultaneously, this growth is creating opportunities for the development of a new class of devices more oriented towards general-purpose use and capable of capturing both high-frequency signals for short-term, event-driven motion analysis and low-frequency signals for extended monitoring. For such a design, which combines flexibility and low cost, a rigorous evaluation of the device in terms of deviation, noise levels, and precision is essential. This evaluation is crucial for identifying potential improvements and refining the design accordingly, yet it is rarely addressed in the literature. This paper presents the development process of such a device. The results of the design process demonstrate acceptable performance in optimizing energy consumption and storage capacity while highlighting the most critical optimizations needed to advance the device towards the goal of a smart, general-purpose unit for human motion monitoring. [ABSTRACT FROM AUTHOR]

Featured Application: The proposed kinematic analysis protocol can play a role in detecting electromyographic and kinematic alterations of the shoulder for the pre-clinical detection of the risk factors for overuse pathologies. Moreover, the proposed exercise prevention protocol has shown valuable results in optimizing shoulder movement and can be proposed to overhead athletes as a part of their athletic preparation. Scapular dyskinesia, glenohumeral internal rotation deficit, upper posterior labral anterior tears, and rotator cuff injuries are common in athletes who play "overhead" sports due to their repetitive excessive movements. The aims of this study are to propose a new protocol with kinematic analysis coupled with sEMG and to objectively analyze the effect of a specific prevention exercise protocol. Thirty-two subjects (age: 22 ± 4 years, height: 183 ± 3.2 cm, BMI: 23 ± 0.96 kg/m2), including sixteen healthy subjects (Group A) and sixteen male water polo athletes (Group B), underwent a three-dimensional motion analysis based on optoelectronic and sEMG systems. A functional evaluation was performed on Group A and Group B to assess the reliability of the operator-dependent tasks and collect a series of normative data, before starting the prevention protocol (T0) and after 8 weeks (T1). The athletes performed a specific exercise protocol to prevent shoulder injuries. In Group B, the movements of abduction (T0: 111° ± 24°; T1: 140° ± 13°) and extension (T0: 72°± 10°; T1: 84° ± 2.8°) of the glenohumeral joint and the scapulothoracic joint (T0: 33° ± 8.36°; T1: 40.5° ± 10.6°) significantly improved. A significant reduction (in %) in the maximum voluntary contraction (MCV) at T1 of the upper trapezius, teres minor, and pectoralis major was observed. This protocol provides objective data in a simple and reliable way for the functional assessment of the shoulder in water polo players during the sport season. [ABSTRACT FROM AUTHOR]

For convenient comparison and clear physical meaning, the gravity on the surface of a homogeneous cube and on spheres inside, outside, and intersecting about it is calculated by polyhedral or harmonic expansion methods. In addition, the gravity coefficients of a rectangle's spherical harmonics are both derived analytically and evaluated numerically, where only five terms are nontrivial up to the order of 4, which is somewhat unexpected when we first obtained them. There are some similarities of these coefficients to an ellipsoid for the terms C20,C22,C42, but they are much different for the terms C40,C44. Thence, a few special gravity characteristics are here revealed or visualized. For example, it is shown as expected that the maximum gravity appears at the sphere intersecting the cube, but maximum surface gravity at the center of the mid-plane of a rectangle's surface is different from the gravity on an ellipsoid at the end of its short axis. Based on these results, an orbit around a cube is integrated by a polyhedral method, and its secular motion analysis by averaging theory is investigated where the numerical and analytic results fit very well. Finally, a few special trajectories on a surface plane of a cube are simulated; the physical meaning is quite clear, and some insights are shown, such as why a natural celestial body in the shape of a rectangle with sharp corners is rarely found due to its surface gravity distribution. All gravity calculations are visualized on 3D figures both for cubes or rectangles. Additionally, examples of an asteroid and an ellipsoid are shown so that the techniques discussed here can be adopted to directly analyzing the gravity of other shapes. [ABSTRACT FROM AUTHOR]

The excited, one-degree-of-freedom mechanical system with symmetrical and asymmetrical rigid constraints, is investigated in a two-parameter bifurcation plane ω–b. Decision conditions for the chattering-sticking motion of the system are given. The analytical solution of P(1, 1, 1) periodic motion and the linearization matrix of the Poincaré map are derived. The bifurcation characteristics of the P(1, 1, 1) periodic motion are analyzed theoretically by the position of the eigenvalue passing through the unit circle. The multiplicity and evolution of periodic motions of the system with symmetrical and asymmetrical constraints are explained by zones of their occurrence and stability in the plane of ω–b. Special attention is given to the complex dynamics near the singular points Si and the mutual transfer law of adjacent P(1,r,r) motion. The singular point is a codimensional-2 grazing bifurcation point related to P(1,r,r) type, and also a codimensional-2 flip-fold bifurcation point related to P(1,r + 1,r + 1) motion. The mutual evolution of adjacent P(1,r,r) motion is reversible only at the singular point Si. For symmetrical system, motions P(1,r + 1,r), P(2, 2r, 2r + 1), P(3, 3r + 1, 3r + 1) and their evolutions emerge in the ligulate zone. For an asymmetrical system, a cluster of abnormal basic groups gathers in the low-frequency. The symmetrical constraint model is a special case of the asymmetrical model. The obtained results have reference value for reducing component wear, noise, and improving the operational reliability of mechanical systems with clearance couplings. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The behavior of pedestrians in a non-constrained environment is difficult to predict. In wearable robotics, this poses a challenge, since devices like lower-limb exoskeletons and active orthoses need to support different walking activities, including level walking and climbing stairs. While a fixed movement trajectory can be easily supported, switches between these activities are difficult to predict. Moreover, the demand for these devices is expected to rise in the years ahead. In this work, we propose a cloud software system for use in wearable robotics, based on geographical mapping techniques and Human Activity Recognition (HAR). The system aims to give context to the surrounding pedestrians by providing hindsight information. The system was partially implemented and tested. The results indicate a viable concept with great extensibility prospects. [ABSTRACT FROM AUTHOR]

Skeleton-based action recognition, renowned for its computational efficiency and indifference to lighting variations, has become a focal point in the realm of motion analysis. However, most current methods typically only extract global skeleton features, overlooking the potential semantic relationships among various partial limb motions. For instance, the subtle differences between actions such as "brush teeth" and "brush hair" are mainly distinguished by specific elements. Although combining limb movements provides a more holistic representation of an action, relying solely on skeleton points proves inadequate for capturing these nuances. Therefore, integrating detailed linguistic descriptions into the learning process of skeleton features is essential. This motivates us to explore integrating fine-grained language descriptions into the learning process of skeleton features to capture more discriminative skeleton behavior representations. To this end, we introduce a new Linguistic-Driven Partial Semantic Relevance Learning framework (LPSR) in this work. While using state-of-the-art large language models to generate linguistic descriptions of local limb motions and further constrain the learning of local motions, we also aggregate global skeleton point representations and textual representations (which generated from an LLM) to obtain a more generalized cross-modal behavioral representation. On this basis, we propose a cyclic attentional interaction module to model the implicit correlations between partial limb motions. Numerous ablation experiments demonstrate the effectiveness of the method proposed in this paper, and our method also obtains state-of-the-art results. [ABSTRACT FROM AUTHOR]

Gait monitoring using hip joint angles offers a promising approach for person identification, leveraging the capabilities of smartphone inertial measurement units (IMUs). This study investigates the use of smartphone IMUs to extract hip joint angles for distinguishing individuals based on their gait patterns. The data were collected from 10 healthy subjects (8 males, 2 females) walking on a treadmill at 4 km/h for 10 min. A sensor fusion technique that combined accelerometer, gyroscope, and magnetometer data was used to derive meaningful hip joint angles. We employed various machine learning algorithms within the WEKA environment to classify subjects based on their hip joint pattern and achieved a classification accuracy of 88.9%. Our findings demonstrate the feasibility of using hip joint angles for person identification, providing a baseline for future research in gait analysis for biometric applications. This work underscores the potential of smartphone-based gait analysis in personal identification systems. [ABSTRACT FROM AUTHOR]

Given the problems such as insufficient control on pests and diseases or pesticide damage on plants caused by uneven distribution of pesticide droplets during the current application process by UAVs, this paper designed novel uniform application equipment with nozzles swinging horizontally based on a UAV platform in order to improve the distribution uniformity of droplets volume. Nozzles swinging periodically are able to increase the overlap probability of spray fans generated from nozzles. It is helpful to further the spray deposition uniformity improvement. Through droplet motion analysis, CFD simulation, and spray tests, it was determined that the key factors affecting uniformity were the oscillating rod length, spray height, and nozzle angle. The best parameter combination was explored as the length of 175 mm, the height of 1.5 m, and the angle of 15°. Based on this combination, the prototype was produced and installed on the UAV platform. A field test was carried out to verify its performance. The results showed that the CV of the improved UAV was 26.41%, which was 6.43 percentage points lower than the traditional UAV, and the decrease was 19.58%, meaning that it is feasible to use this equipment to improve uniformity. [ABSTRACT FROM AUTHOR]

Background: The objective of our study was to biomechanically evaluate the use of kyphoplasty to stabilize post-traumatic segmental instability in incomplete burst fractures of the vertebrae. Methods: The study was performed on 14 osteoporotic spine postmortem samples (Th11–L3). First, acquisition of the native multisegmental kinematics in our robot-based spine tester with three-dimensional motion analysis was set as a baseline for each sample. Then, an incomplete burst fracture was generated in the vertebral body L1 with renewed kinematic testing. After subsequent kyphoplasty was performed on the fractured vertebral body, primary stability was examined again. Results: Initially, a significant increase in the range of motion after incomplete burst fracture generation in all three directions of motion (extension–flexion, lateral tilt, axial rotation) was detected as proof of post-traumatic instability. There were no significant changes to the native state in the adjacent segments. Radiologically, a significant loss of height in the fractured vertebral body was also shown. Traumatic instability was significantly reduced by kyphoplasty. However, native kinematics were not restored. Conclusions: Although post-traumatic segmental instability was significantly reduced by kyphoplasty in our in vitro model, native kinematics could not be reconstructed, and significant instability remained. [ABSTRACT FROM AUTHOR]

To define the regular upper eyelid anatomy and their changes during dynamic motion using ultrasonographically depicted structures. A cross-sectional study. High-resolution ultrasound biomicroscopy (50MHz) was performed on 84 upper eyelids of 42 healthy volunteers without evidence of eyelid conditions. The skin-orbicularis oculi complex (SOOC), levator aponeurosis, and Müller's muscle-conjunctival complex were imaged. The thickness of these structures was measured in primary gaze and downgaze positions. SOOC and levator aponeurosis thickness was bigger with eyes open than with eyes closed (p < 0.01). With eyes closed, the thickness of SOOC on the pupillary midline and levator aponeurosis was positively correlated with age (p < 0.05, p < 0.01, respectively), and the thickness of levator aponeurosis and SOOC on the pupil midline was also positively correlated with BMI index (p < 0.05). Similarly, SOOC thickness on the medial and lateral canthus line is also positively correlated with BMI index and age (p < 0.05, p < 0.01, respectively). As for the differences between genders, the mean thickness of SOOC and levator aponeurosis was statistically different (p < 0.05, respectively). The magnitude of levator aponeurosis thickness in men varied more than in women in different ocular positions (p < 0.05). All measurements had an intramethod between 0.624 and 0.792, and inter-rater ICC and intrarater ICC between 0.748 and 0.850. Ultrasound biomicroscopy represents a noninvasive tool for the visualization of upper eyelid morphology. Expanding its application can help to understand the dynamics of upper eyelid physiological movement, aging, and disease research in different populations and evaluate surgical outcomes. [ABSTRACT FROM AUTHOR]

The overtopping-inundation process of a tsunami results in the collisions of drifting objects on the coast, which damage structures, thereby increasing the risk of collapse. This study conducted laboratory experiments on the collision between a drifting container caused by the overtopping-inundation process of a solitary wave and a fixed port crane's leg. The movement trajectory and velocity of the container as well as the collision velocity by solitary wave inundation, were analyzed using motion analysis software. Overall, increasing solitary wave scale, collision velocity, and drifting object weight and decreased distance between the two objects tended to increase the collision force. However, different experiment results were also obtained due to pitching in objects that fully floated without bottom friction owing to the solitary wave bore. This resulted in line-to-surface collisions. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects. [ABSTRACT FROM AUTHOR]

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Transformer tracking always takes paired template and search images as encoder input and conduct feature extraction and target‐search feature correlation by self and/or cross attention operations, thus the model complexity will grow quadratically with the number of input images. To alleviate the burden of this tracking paradigm and facilitate practical deployment of Transformer‐based trackers, we propose a dual pooling transformer tracking framework, dubbed as DPT, which consists of three components: a simple yet efficient spatiotemporal attention model (SAM), a mutual correlation pooling Transformer (MCPT) and a multiscale aggregation pooling Transformer (MAPT). SAM is designed to gracefully aggregates temporal dynamics and spatial appearance information of multi‐frame templates along space‐time dimensions. MCPT aims to capture multi‐scale pooled and correlated contextual features, which is followed by MAPT that aggregates multi‐scale features into a unified feature representation for tracking prediction. DPT tracker achieves AUC score of 69.5 on LaSOT and precision score of 82.8 on TrackingNet while maintaining a shorter sequence length of attention tokens, fewer parameters and FLOPs compared to existing state‐of‐the‐art (SOTA) Transformer tracking methods. Extensive experiments demonstrate that DPT tracker yields a strong real‐time tracking baseline with a good trade‐off between tracking performance and inference efficiency. [ABSTRACT FROM AUTHOR]

The performance assessment of relevant biomechanical factors is essential for appropriate age-related training progression in volleyball spike (VS). This study aimed to investigate the differences in upper limbs' (a) range of motion (ROM), (b) angular velocities, and (c) muscular activity during VS among under 16- (U-16), under 18- (U-18), and under 20- (U-20) year-old female volleyball players. The kinematic variables of the spike performances were recorded using six optoelectronic cameras (Vicon Motion system, UK). Additionally, the wireless Trigno system (Delsys, USA) was used to record the electromyographic signals. The one-way ANOVA (1d SPM analysis) exhibited a significantly greater wrist internal rotation (p <.001), wrist adduction velocity (p <.001), and palmaris longus activity (p <.001) in the acceleration phase in U-20, compared to the U-16 group. Additionally, the U-20 and the U-18 players portrayed a significantly greater shoulder external rotation (p <.001) and internal angular velocity (p =.035) relative to the U-16 group. A significantly greater pectoralis major (p <.001), biceps brachii (p <.001), and anterior deltoid (p <.001) activity was observed in the U-20 group, compared to younger groups. This study suggests that older players employ more upper limb muscular activities during spike with the presence of blocks, which enables them to hit the ball with greater velocities and direct the ball in their desired direction through increased wrist ROMs. [ABSTRACT FROM AUTHOR]

Researchers are actively recommending optimal modes of usage for techno-pedagogical tools to ensure that athletes reap the benefits of technology in their training. In this study, we investigated the most effective video feedback viewing speed among normal-speed (NS), half-speed (HS), and quarter-speed (QS), for technical error correction in young weightlifters during the snatch movement. A total of 37 weightlifters (25 boys and 12 girls), aged 11–12 years, were randomly divided into three groups, namely the normal-speed (control group), the half-speed, and the quarter-speed group. Participants completed a pretest (T0), a seven-week snatch learning unit, and a posttest (T1), as well as a retention test one week later (T2). Video-mediated technical analysis of the snatch movement was conducted using the Kinovea motion analysis software. The main results showed that weightlifters who viewed their feedback videos at a quarter of the normal speed (QS) achieved significantly greater improvements in the displacement of the bar in the first pull Dx2 (T1 vs. T0: 27.41 ± 26.10%, Hedges' g = 0.87, p < 0.05; T2 vs. T0: 24.34 ± 27.11%, Hedges' g = 1.07, p < 0.05) and the vertical displacement VTR (T1 vs. T0: 22.89 ± 14.16%, Hedges' g = 1.16, p < 0.05) compared to those who viewed the videos at NS or HS. These findings suggest that slowing down video feedback playback to a quarter of the normal speed can be an effective strategy for enhancing technical error correction in young weightlifters. [ABSTRACT FROM AUTHOR]

Introduction: As 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). Methods: Sagittal 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. Results: The 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. Conclusion: The 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, midsternum, and 1st and 10th thoracic spinous processes. [ABSTRACT FROM AUTHOR]

With the rapid development of marine engineering in recent years, offshore operations have become increasingly common, making wave compensation platforms crucial for safe operations at sea. This paper presents a pendulum-type wave compensation platform specifically designed for wave compensation applications. The main components of this wave compensation platform include a chassis, support base, hydraulic cylinders, telescopic rods, upper platform, three sets of balancing mechanisms, three sets of tilt angle sensors, and a control system. Firstly, to thoroughly understand the compensatory motion of the pendulum-type three-degree-of-freedom wave compensation platform, kinematic analysis of the entire system was conducted, and the motion inverse solution curves of the mechanism were obtained through simulation using motion simulation software. Secondly, to enhance the compensatory response performance of the platform, a fuzzy PID control algorithm was employed to control the system and achieve attitude control of the platform. Finally, through control system simulation, compared to PID control, fuzzy PID reduces system response delay and successfully meets the expected technical requirements and application needs. [ABSTRACT FROM AUTHOR]

(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. [ABSTRACT FROM AUTHOR]