Joint Coordinates Research Articles

PRINCIPLES OF IMPLEMENTING LOCAL SELF-GOVERNMENT IN CONDITIONS OF MARTIAL STATE

The article highlights the principles of local self-government in the conditions of martial law, starting from February 2014 and especially during the period of the full-scale invasion of the Russian Federation into the territory of Ukraine. The provisions of individual regulatory legal acts regulating the activities of local self-government bodies during the period of the special legal regime are considered. The article analyzes the key tasks facing local councils, executive committees and other self-government bodies in ensuring the vital activity of territorial communities, public safety, the functioning of critical infrastructure and social protection of the population. Special attention is paid to the interaction of local authorities with military administrations, central government bodies and public associations in the context of joint coordination of efforts to support the state's defense capability. Institutional changes and the need for rapid adaptation of management processes to the challenges of wartime are identified. The role of local government in building community resilience, attracting resources for the restoration of damaged infrastructure and organizing humanitarian aid is investigated. The article outlines the main problems faced by local governments in wartime, including resource constraints, personnel challenges, the need for rapid decision-making and implementation in crisis situations. It suggests ways to improve local governance mechanisms, including the introduction of digital technologies and strengthening the legal framework for effective work during martial law.

Gait-To-Gait Emotional Human–Robot Interaction Utilizing Trajectories-Aware and Skeleton-Graph-Aware Spatial–Temporal Transformer

The emotional response of robotics is crucial for promoting the socially intelligent level of human–robot interaction (HRI). The development of machine learning has extensively stimulated research on emotional recognition for robots. Our research focuses on emotional gaits, a type of simple modality that stores a series of joint coordinates and is easy for humanoid robots to execute. However, a limited amount of research investigates emotional HRI systems based on gaits, indicating an existing gap in human emotion gait recognition and robotic emotional gait response. To address this challenge, we propose a Gait-to-Gait Emotional HRI system, emphasizing the development of an innovative emotion classification model. In our system, the humanoid robot NAO can recognize emotions from human gaits through our Trajectories-Aware and Skeleton-Graph-Aware Spatial–Temporal Transformer (TS-ST) and respond with pre-set emotional gaits that reflect the same emotion as the human presented. Our TS-ST outperforms the current state-of-the-art human-gait emotion recognition model applied to robots on the Emotion-Gait dataset.

A biomechanical study of the jumping muscles of gymnasts for specific abilities

This biomechanical study investigates the muscle group-specific abilities of gymnasts during the jump take-off, focusing on the hip, knee, and ankle joints. Using 3D kinematic and kinetic analysis, the study explores the role of these joints in jump height, reaction time, and stability. Key findings show that centrifugal contraction of the hip extensor muscles enhances jump stability, while the knee joint’s transition from centrifugal to centripetal contraction is critical for responding to ground reaction forces and generating vertical velocity. The ankle joint’s power output during centripetal contraction is crucial for vertical acceleration. Moreover, the synchronization between these joints significantly influences the overall efficiency of the jump, highlighting the importance of joint coordination in maximizing performance. The ability of the knee to rapidly switch from a flexion to extension phase also plays a vital role in controlling the impact forces and optimizing take-off velocity. This research provides important insights into the biomechanics of gymnastics jumping and informs targeted plyometric training to optimize jump performance.

Biomechanical disparities in pankration: A comparative computational analysis of ancient and contemporary techniques

Abstract Study aim: The study analyzed biomechanical similarities and differences between ancient and modern sports techniques, focusing on pankration. It examined historical artifacts and modern pankration scenes to elucidate biomechanical developments over time. Material and methods: OpenPose was employed for this analysis, focusing on both ancient depictions of pankration and contemporary pankration footage. The methodology involved collecting and analyzing depictions of archaeological artifacts, examining video performances frame by frame, and applying computational analysis to determine the Cartesian two-dimensional coordinates of joints. Comparative vector mapping and kinematic analyses were used for assessment. Results: The analysis revealed distinct biomechanical patterns between ancient and modern pankration techniques. It was found that ancient techniques primarily leverage gravity for movement execution, while modern techniques emphasize the utilization of muscular capacity. This distinction indicates a transformation in biomechanical strategy, shifting from a gravity-focused approach in ancient practices to a muscle-focused approach in modern practices. Conclusions: The research highlights the differences between ancient and modern pankration, emphasizing punching and kicking techniques. These changes reflect broader shifts in athletic practices over time, influenced by cultural and historical factors, and similar disciplines. The study not only enhances our understanding of ancient sports biomechanics but also opens avenues for future exploration of other ancient athletic disciplines using current computational methods.

Goal-equivalent drifts in sagittal joint angle configuration as indicators of optimality in postural alignment.

The relevance of posture as a constituent of physical health varies depending on one's explanatory framework of disease. Contrasting perspectives within this discussion refer to optimal biomechanics, but often without consistent meaning. The resulting theoretical confusion presents challenges both for applied research and clinical practice. We studied joint angle drift tendencies and sway-stabilizing synergy as indicators of optimality in relaxed bipedal standing. Sixteen subjects completed a series of 4-min bipedal standing trials under varying foot positions. Kinematic time series were segmented on the basis of multivariate changepoint location to quantify directional tendencies associated with slow, unintentional joint angle drifts. Subsequently, time series were segmented into shorter epochs and synergy indices describing center of mass stabilizing joint coordination were quantified for each epoch. Paired t-tests were used to assess the tendency of observed drifts to approximate common endpoints and "Random Effects Within Between" models were used to assess the relationship between synergy indices and Euclidean distance from individually defined drift targets. Our analyses suggest that 1) joint angles in relaxed bipedal standing tend to drift toward specific endpoints, and 2) greater deviation from these drift endpoints associates with greater COM-stabilizing coordinative synergy. We interpret these findings as supporting the presence of latent cost functions associated with individual sagittal joint angle configuration. We discuss our work in the context of the ongoing theoretical and clinical dialogue concerning optimal movement and the relevance of biomechanics in physical health.

Pemberdayaan Lansia dalam Melakukan Aktivitas Fisik Senam Lansia untuk Meningkatkan Tingkat Kemandirian Lansia

Background: Aging leads to physical deterioration, which makes the elderly dependent on others for daily activities. One way to increase their independence is through physical activities such as elderly gymnastics. Regular participation in elderly gymnastics can restore physical function, improve joint, muscle, and movement coordination, and enhance heart function, leading to a healthier and fitter body. Method: The program began with a preparation stage, followed by elderly gymnastics training and counseling. This activity took place in one session, targeting both independent and assisted elderly individuals. The elderly gymnastics included basic exercises with a warm-up, core movements, and cooling down, lasting approximately 15-30 minutes. Afterward, an evaluation of the activity was conducted. Results: A total of 60 elderly individuals participated in the gymnastics session, which included warm-up, core, and cooling exercises. The participants appeared enthusiastic and easily followed the movements, especially with music accompaniment. However, some had difficulty with foot movements due to balance issues. After the gymnastics session, counseling was provided on the importance of doing elderly gymnastics independently. The elderly were very engaged during the counseling and asked several questions afterward. Conclusion: Elderly gymnastics can be incorporated as a routine activity in elderly health programs like posyandu, helping the elderly become more independent with a healthy and fit body. Regular participation in these exercises can improve their ability to perform daily activities independently.

Impact of Contralateral Hemiplegia on Lower Limb Joint Kinematics and Dynamics: A Musculoskeletal Modeling Approach

This study investigates the biomechanical differences between typically developed (TD) individuals and those with contralateral hemiplegia (CH) using musculoskeletal modeling in OpenSim. Ten TD participants and ten CH patients were analyzed for joint angles and external joint moments around the three anatomical axes: frontal, sagittal, and transverse. The analysis focused on hip, pelvis, lumbar, knee, ankle, and subtalar joint movements, leveraging MRI-derived bone length data and gait analysis. Significant differences (p < 0.05) were observed in hip flexion, pelvis tilt, lumbar extension, and ankle joint angles, highlighting the impact of hemiplegia on these specific joints. However, parameters like hip adduction and rotation, knee moment, and subtalar joint dynamics did not show significant differences, with p > 0.05. The comparison of joint angle and joint moment correlations between TD and CH participants highlights diverse coordination patterns in CH. Joint angles show significant shifts, such as HF and LR (−0.35 to −0.97) and PR and LR (0.22 to −0.78), reflecting disrupted interactions, while others like HR and LR (0.42 to 0.75) exhibit stronger coupling in CH individuals. Joint moments remain mostly stable, with HF and HA (0.54 to 0.53) and PR and LR (−0.51 to −0.50) showing negligible changes. However, some moments, like KA and HF (0.11 to −0.13) and PT and KA (0.75 to 0.67), reveal weakened or altered relationships. These findings underscore biomechanical adaptations and compensatory strategies in CH patients, affecting joint coordination. Overall, CH individuals exhibit stronger negative correlations, reflecting impaired coordination. These findings provide insight into the musculoskeletal alterations in hemiplegic patients, potentially guiding the development of targeted rehabilitation strategies.

Path planning for flexible needle based on both insertion mechanism kinematics and needle bending model.

Due to the limited operating space in the magnetic resonance (MR) environment, there is coupled motion in the insertion mechanism, which not only reduces the flexibility of the robot but also challenges the insertion path planning. Meanwhile, the path planning is also restricted by the bending rule of the flexible needle, thus the bending model of the needle is also essentially built. This paper proposes a path planner for the flexible needle based on both the coupled motion kinematics of the insertion robot and the bending model of the flexible needle. A kinematic analysis for the coupled motion of insertion robot is performed. And the bending model of flexible needle is established based on the needle-tissue interactions. The position and posture of the needle insertion at the entry point are obtained by the calculation of the target position and the analysis of the bending model. And the rotation or translation coordinates of each robot joint are calculated by the inverse kinematics of the insertion robot. Then the path planning based on the coupled kinematics and the bending model is realized. The insertion experiments were performed for each target of G1 and G2. The root mean square errors were 0.83 mm and 0.74 mm, and the maximum errors were 1.1 mm and 0.9 mm for G1 and G2, respectively. The experimental results show that the effectiveness and accuracy of the path planning can meet the requirements for a general minimally invasive surgery, so the proposed path planning algorithm is feasible. This study provides a new solution for the path planning of insertion robots for the minimally invasive surgery. This method can meet the insertion mechanism working within the limited operating space in the MR environment and has a high application value in future clinical medicine.

The state-representative and corporate-legal nature of the benevolence of judges: a discussion on European standards

It is indicated that the right to a fair trial is guaranteed by Article 6 of the European Convention on Human Rights. The effective exercise of this right requires, in particular, that everyone has the right to be heard by «an independent and impartial tribunal established by law to determine civil rights and obligations or determine the merits of any criminal charge brought against him». The article is devoted to the analysis of the compliance of national legal regulation with European standards regarding the integrity of the judicial corps and the determination of the legal nature of this phenomenon in the public­authority and professional-labor sphere. It is indicated that the paradigm of the functioning of the judicial system contains the requirements of professionalism, independence and integrity of the administration of justice, which forms the basis of the development of statehood and the establishment of the principles of the rule of law, which is a requirement of international and European judicial standards. It is reasoned that the state-representative function of the integrity of judges is manifested in the high professional and moral compliance of the judicial corps with the requirements for the high position of a judge. The requirements are broader than for the integrity of other employees, let’s say, executive and local self-government bodies, due to the fact that judges are endowed with unique powers - to protect and restore rights and freedoms, legitimate interests on behalf of the state. The corporate and public nature of integrity is singled out as a professional criterion for judges (judge candidates) in order to meet the position held, which is due primarily to the fact that the judiciary takes place through the implementation of activities based on the judge’s legal awareness and the state provides them with a sufficiently wide discretion to implement powers This nature is manifested in openness and transparency, which is a guarantee of achieving the integrity of judges and the judiciary and judicial self-government. Based on the conclusions of the Advisory Council of European Judges, it is proven that overcoming corruption as a manifestation of dishonesty contributes to the general level of legitimization, where functional legitimacy is based on public trust, which is created through excellent work, transparency, accountability. The hypothetical effectiveness of the new model of corporate labor relations developed in our country has been proven - the joint coordination work of judicial self-government bodies, civil society and independent international experts.

The Challenges of Intergovernmental Organizations in Combating Transnational Crime: An Indonesian Perspective

Human trafficking is a pressing global issue, especially in the Southeast Asian region, where Indonesia plays a role as a country of origin, transit and destination. This study aims to identify the cooperation between the Indonesian Police and ASEANAPOL using descriptive qualitative research methods. This research also highlights the role of ASEANAPOL through 4 strategies of handling Indonesian Police in collaboration with ASEANAPOL which include capacity building through training (ATCM), international meetings (AMMTC and SOMTC), electronic-based real-time information exchange (System e-ADS), and strengthening cross-border investigation mechanisms through the Joint Coordination System (JCS) with border guarding and dispatching personnel such as Attache POLRI (ATPOL) and POLRI Technical Staff (STAFNISPOL). While this research focuses on preventive responses to human trafficking, there are limitations that need to be considered, including aspects of prevention and prosecution involving victim identification and protection. Future research is recommended to explore all aspects, including prevention and prosecution measures, to develop ASEANAPOL’s organisational framework in addressing transnational crimes.

The role of cognitive load on interlimb differences in motor coordination in older adults.

Although the dominant hand has been shown to have performance advantages over the nondominant hand, these interlimb differences have found to be dependent on task and biomechanical demands. The dynamic dominance hypothesis suggests that the left hemisphere is specialized for the control of intersegmental dynamics while the nondominant right hemisphere is specialized for postural control, in right-handers. In a real-world scenario, however, cognitive challenges might be expected to modulate these specialized behaviors. Therefore, we hypothesized that with increased cognitive load, lateralized motor control processes would become even more asymmetrical. We recruited 16 right-handed older adults (11 females, 5 males; 65.88 yr ± 1.99 SE) to perform 170 trials of a unilateral reaching task with each of their hands on the Kinereach system. In each trial, participants rapidly memorized pictorial instructions before identifying and reaching for the correct object on a screen. The complexity of the task increased over the course of the experiment. Our results demonstrated higher reaction times in the right than in the left hand (P = 0.0004). Movements became increasingly curved and erroneous with cognitive load, but interlimb differences in movement quality were absent. We found higher joint cocontraction in the right than in the left arm (P < 0.05), but these differences were unaffected by cognitive load. Hence, with the addition of a cognitive load, we observed asymmetries in reaction time but not in joint coordination or movement quality. This highlights the role of cognitive load in modulating limb/hemisphere specializations for control processes.NEW & NOTEWORTHY Although we know that motor control processes are lateralized to each hemisphere, the role of cognitive load on these specialized processes is undefined. We designed a unique task that incorporates a cognitive challenge to a typical reaching movement to examine how cognitive load affects limb asymmetries in motor control. In a group of typical older adults, we demonstrated interlimb asymmetries in reaction time but not in joint coordination or movement quality.

Self-other distinction modulates the sense of self-agency during joint actions

In daily life interactions, we achieve goals with partners through tight temporal coordination or sequential joint efforts. Is our individual sense of control over shared outcomes (sense of self-agency) the same as the one experienced when we act alone? Do we explicitly and implicitly feel like we are fully in control of the motor act even if the goal is finally achieved by our partner? To address these questions, we measured explicit and implicit sense of self-agency in individual and (coordinated or sequential) interactive contexts. We studied 42 healthy adult participants during active/passive button presses aimed at turning on a light bulb. This goal could be achieved individually (Solo condition) or by interacting with a partner (Joint condition) synchronously (joint Coordination task) or sequentially (joint Sequential task). We collected trial-by-trial explicit judgments of self-agency. To quantify the intentional binding phenomenon, an index of implicit sense of agency, we also measured the perceived compression of the time interval between the active or passive movements and their outcomes. Explicit sense of agency: we observed decreased judgments of self-agency in Joint trials compared with the Solo ones in both the Coordination and Sequential tasks. Implicit sense of agency: in the Coordination task, we found a significant intentional binding effect only in Solo trials but not in Joint ones. For the Sequential task, however, a significant intentional binding was also present in the Joint condition. Our results indicate that the individual sense of agency is reduced during joint actions, yet this can be restored at an implicit level when the format of the motor interaction makes the individual contribution to goal achievement more obvious. We discuss these results considering current cognitive theories on motor awareness and interactions.

Lower limb gait joint coordination variability in people with diabetes-related foot ulcers

BackgroundDiabetes-related foot ulcers pose substantial health risks globally, yet the biomechanical intricacies underlying their development remain incompletely understood. This study aimed to evaluate lower limb gait joint coordination variability in individuals with diabetes-related foot ulcers compared to those with diabetes (without diabetes-related foot ulcers) and healthy controls. MethodsA total of 99 participants (diabetes-related foot ulcers cases – 16, Diabetes controls – 50, Health controls – 33) compared three self-paced walking trials. Vector coding, a technique quantifying movement coordination, was employed, analysing hip-knee, knee-ankle, and hip-angle joint couplings in the sagittal plane. FindingsNo significant differences in coordination variability were found among the groups. However, distinct coupling pattern frequencies emerged, with diabetes-related foot ulcers cases exhibiting unique anti-phase hip and ankle coupling frequency counts compared to healthy controls. InterpretationThese findings challenge conventional understandings of diabetes-related foot ulcers biomechanics and underscore the complexity of gait in this population.

Intralimb Coordination Pattern of the Lower Limbs in Male Athletes With Allograft and Autograft Anterior Cruciate Ligament Reconstruction During Landing

Background and Objectives: Two common choices exist for anterior cruciate ligament (ACL) reconstruction, autograft and allograft. Hamstring tendon autografts and soft-tissue allografts are commonly used for ACL reconstruction. The outcomes between these two grafts are controversial. This research aims to quantify and compare lower limb joint coordination between two ACL reconstruction graft options and healthy individuals. Methods: Sixty-one athletes were enrolled after ACL reconstruction surgery (allograft, n=22; autograft, n=18). Furthermore, twenty-one healthy athletes were considered in the control group. The inclusion criteria included unilateral anterior cruciate ligament reconstruction surgery with allograft and autograft methods, male athletes with a minimum of 9 months and a maximum of two years since their surgery, successfully passing a series of quadriceps and hamstring strength tests and distance jumping before entering sports-specific activities under the supervision of a sports physiotherapist, and returning to pre-injury sports activities. Results: Autograft was not statistically different from matched healthy limbs in terms of joint coordination variability and magnitude (P&gt;0.05). However, the magnitude of joint coordination was superior to the allograft group compared to the autograft reconstructed ACL (P&lt;0.05). Conclusion: Although our result reported no significant difference between groups in joint coordination variability, having an insight into coordinative function after ACL reconstruction will help develop postoperative rehabilitation programs as well as minimize the re-injury risk among patients. We also suggest that scholars should conduct more robust trials with valid research designs to control the results of ACL reconstruction comparison with autograft and allograft.

Dynamics of Dominance in Interacting Zebrafish

While two-body fighting behavior occurs throughout the animal kingdom to settle dominance disputes, important questions such as how the dynamics ultimately lead to a winner and loser are unresolved. Here we examine fighting behavior at high resolution in male zebrafish. We combine multiple cameras, a large volume containing a transparent interior cage to avoid reflection artifacts, with computer vision to track multiple body points across multiple organisms while maintaining individual identity in three dimensions. In the body point trajectories we find a spectrum of timescales which we use to build informative joint coordinates consisting of relative orientation and distance. We use the distribution of these coordinates to automatically identify fight epochs, and we demonstrate the postfight emergence of an abrupt asymmetry in relative orientations—a clear and quantitative signal of hierarchy formation. We identify short-time, multi-animal behaviors as clustered transitions between joint configurations, and show that fight epochs are spanned by a subset of these clusters, which we denote as maneuvers. The resulting space of maneuvers is rich but interpretable, including motifs such as “attacks” and “circling.” In the longer-time dynamics of maneuver frequencies we find differential and changing strategies, including that the eventual loser attacks more often towards the end of the contest. Our results suggest a reevaluation of relevant assessment models in zebrafish, while our approach is generally applicable to other animal systems. Published by the American Physical Society 2024

Computational joint action: Dynamical models to understand the development of joint coordination.

Coordinating with others is part of our everyday experience. Previous studies using sensorimotor coordination games suggest that human dyads develop coordination strategies that can be interpreted as Nash equilibria. However, if the players are uncertain about what their partner is doing, they develop coordination strategies which are robust to the actual partner's actions. This has suggested that humans select their actions based on an explicit prediction of what the partner will be doing-a partner model-which is probabilistic by nature. However, the mechanisms underlying the development of a joint coordination over repeated trials remain unknown. Very much like sensorimotor adaptation of individuals to external perturbations (eg force fields or visual rotations), dynamical models may help to understand how joint coordination develops over repeated trials. Here we present a general computational model-based on game theory and Bayesian estimation-designed to understand the mechanisms underlying the development of a joint coordination over repeated trials. Joint tasks are modeled as quadratic games, where each participant's task is expressed as a quadratic cost function. Each participant predicts their partner's next move (partner model) by optimally combining predictions and sensory observations, and selects their actions through a stochastic optimization of its expected cost, given the partner model. The model parameters include perceptual uncertainty (sensory noise), partner representation (retention rate and internale noise), uncertainty in action selection and its rate of decay (which can be interpreted as the action's learning rate). The model can be used in two ways: (i) to simulate interactive behaviors, thus helping to make specific predictions in the context of a given joint action scenario; and (ii) to analyze the action time series in actual experiments, thus providing quantitative metrics that describe individual behaviors during an actual joint action. We demonstrate the model in a variety of joint action scenarios. In a sensorimotor version of the Stag Hunt game, the model predicts that different representations of the partner lead to different Nash equilibria. In a joint two via-point (2-VP) reaching task, in which the actions consist of complex trajectories, the model captures well the observed temporal evolution of performance. For this task we also estimated the model parameters from experimental observations, which provided a comprehensive characterization of individual dyad participants. Computational models of joint action may help identifying the factors preventing or facilitating the development of coordination. They can be used in clinical settings, to interpret the observed behaviors in individuals with impaired interaction capabilities. They may also provide a theoretical basis to devise artificial agents that establish forms of coordination that facilitate neuromotor recovery.

Home-based guidance training system with interactive visual feedback using kinect on stroke survivors with moderate to severe motor impairment

The home-based training approach benefits stroke survivors by providing them with an increased amount of training time and greater feasibility in terms of their training schedule, particularly for those with severe motor impairment. Computer-guided training systems provide visual feedback with correct movement patterns during home-based training. This study aimed to investigate the improvement in motor performance among stroke survivors with moderate to severe motor impairment after 800 min of training using a home-based guidance training system with interactive visual feedback. Twelve patients with moderate to severe stroke underwent home-based training, totaling 800 min (20–40 min per session, with a frequency of 3 sessions per week). The home-based guidance training system uses Kinect to reconstruct the 3D human body skeletal model and provides real-time motor feedback during training. The training exercises consisted of six core exercises and eleven optional exercises, including joint exercises, balance control, and coordination. Pre-training and post-training assessments were conducted using the Fugl-Meyer Assessment-Upper Limb (FMA-UE), Fugl-Meyer Assessment-Lower Limb (FMA-LE), Functional Ambulation Categories (FAC), Berg Balance Scale (BBS), Barthel Index (BI), Modified Ashworth Scale (MAS), as well as kinematic data of joint angles and center of mass (COM). The results indicated that motor training led to the attainment of the upper limit of functional range of motion (FROM) in hip abduction, shoulder flexion, and shoulder abduction. However, there was no improvement in the active range of motion (AROM) in the upper extremity (U/E) and lower extremity (L/E) joints, reaching the level of the older healthy population. Significant improvements were observed in both left/right and superior/inferior displacements, as well as body sway in the mediolateral axis of the COM, after 800 min of training. In conclusion, the home-based guidance system using Kinect aids in improving joint kinematics performance at the level of FROM and balance control, accompanied by increased mediolateral body sway of the COM for stroke survivors with moderate to severe stroke. Additionally, spasticity was reduced in both the upper and lower extremities after 800 min of home-based training.

Dynamics of a knuckle crane carrying a load subjected to wind pressure

AbstractThe paper presents the authors’ model of a knuckle crane offshore type that takes into account the flexibility of boom and drives, which is used to analyze the effect of constant wind pressure or cyclical gusts on the dynamics of the crane and the load. The mathematical model of the crane is derived using a formalism of joint coordinates, homogeneous transformation matrices, and Lagrange equations. Using this model, the influence of wind pressure on the torques and forces in the crane drives and on the accuracy of load positioning is investigated. The results show that the influence of wind on the accuracy of load positioning should not be assessed by limiting the observation to the movement of its gravity center but by observing the movement of characteristic points, the corners of the load. Root mean squared (RMS) indicators are used to quantitatively assess this impact on the driving torque and forces, and appropriate indicators are proposed to assess the accuracy of load positioning.

Determining the optimum number of cycles for calculating joint coordination and its variability during running at different speeds: A timeseries analysis

Understanding the intricacies of human movement coordination and variability during running is crucial to unraveling the dynamics of locomotion, identifying potential injury mechanisms and understanding skill development. Identification of minimum number of cycles for calculation of reliable coordination and its variability could help with better test organization and efficient assessment time. By adopting a cross-sectional study design, this study investigated the minimum required cycles for calculating hip-knee, hip-ankle and knee-ankle coordination and their variability using a continuous relative phase (CRP) method. Twenty-nine healthy adults ran on a treadmill at speeds of 9, 12.5, and 16 km.h−1 while 3D kinematic data of their lower limbs were recorded using 6 optoelectronic cameras. Using Intraclass Correlation Coefficient (ICC) analysis, reliability between CRP and its variability (CRPv) in different gait cycles (3, 5, 10, 20, 30) was assessed for each speed. A minimum of 10 cycles was required for CRP calculation across all speeds, whereas CRPv necessitated a minimum of 30 cycles for moderate to good reliability. While increasing the number of cycles improved ICC values for inter-joint CRP, the same trend was not consistently observed for CRPv, emphasizing the importance of separately assessing CRP and its variability metrics.

Influence of medial longitudinal arch flexibility on lower limb joint coupling coordination and gait impulse

BackgroundA causal link exists between structural differences in the foot and alterations in the lower limb biomechanics, which might predispose an individual to develop characteristic musculoskeletal disorders. Research questionThis study aimed to determine how the foot structural characteristics, as represented by the medial longitudinal arch flexibility, affect lower limb joint coupling coordination and anterior-posterior ground reaction impulses (GRIs) during walking and running. MethodsFollowing the calculation of arch height flexibility, a total of fifty-four physically active males were grouped and completed gait experiments to collect kinematic and kinetic data synchronously. Inter-joint coordination and variability were calculated from the angle-angle plots of knee-hip, ankle-knee, and metatarsophalangeal (MTP)-ankle couplings based on an optimized vector coding technique. ResultsOur results indicate that coupling coordination of interest and its variability, as well as anterior-posterior GRIs, could potentially be influenced due to differences in arch height flexibility. Notably, the individuals with stiff arches exhibited significantly greater coordination variabilities during the early stance for both ankle-knee and MTP-ankle coordination yet significantly smaller for MTP-ankle coordination variabilities during the mid-stance phase. Furthermore, combining the statistical parametric mapping analysis results, the flexible arches experienced a greater proportion of GRIs in the anterior-posterior direction. SignificanceIn conclusion, these observations demonstrated that variations in arch flexibility led to differences in lower limb joint coordination variabilities and GRIs during gait. This fresh insight into inter-joint coordinative function may be useful for enhancing foot motion strategies based on arch structural characteristics.