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Musculoskeletal biomechanical models have wide applications in ergonomics, rehabilitation, and injury estimation. Their use can be extended to enable quantitatively explaining and estimating ride comfort for a vehicles passenger. A biomechanical model of the upper body in the sagittal plane is constructed, which allows for curved motion to simulate the propagation of disturbance energy within a seated passenger aboard a moving vehicle. The dynamic predictions of the model are validated against experimental results within the literature. Frequency responses show that within the vehicular frequency range, the L4L5 and the L5S1 discs in the lower lumbar region are susceptible to the highest vibration transmission. It was also found that vibration transmission is maximized at around 4.5 Hz. The model provides analytical and geometric intuition into the motion of the various segments of the upper body using a few simple geometric assumptions and can be employed to develop a quantitative ride-comfort metric, such that the most comfortable ride would be that which would induce the least internal motion within the passenger model.

Fibrin has unique biomechanical properties which are essential for its role as a scaffold for blood clots. Fibrin is highly extensible and demonstrates significant strain stiffening behaviour, which is essential for stress-distribution in the network. Yet the exact structures of fibrin at the sub-fibre level that contribute to its unique biomechanical characteristic are unknown. Here we show how truncations of the fibrinogen αC-region impact the biomechanical properties of fibrin fibres. Surprisingly, absence of the complete αC-region did not influence the low strain modulus of fibrin fibres but led to premature fibre rupture and decreased extensibility. Intermediate effects were observed with partial deletion of the αC-region, reflected by intermediate rupture stress and toughness. However, overall strain-stiffening behaviour remained even in absence of the αC-region, indicating that strain stiffening is not due to stress being transferred from the αC-region to the protofibril backbone. Upon stress-relaxation, decay constants and their relative contribution to the total relaxation remained similar at all strains, showing that a distinct relaxation process is present until fibre rupture. However, relative contribution of fast relaxation was maximal only in crosslinked fibres if the flexible αC-connector was present. These data show that the αC-region is not the main load-bearing structure within fibrin fibres and point to a critical role for the protofibril backbone instead. We present a revised structural model based on protofibril branching that fully explains the unique biomechanical behaviour of fibrin fibres, while the αC-region primarily acts as a safety latch at the highest of strains. The findings presented in this paper reveal critically important details about how the molecular structure of fibrin contributes to its unique mechanical properties which are essential to fulfil its function as the scaffold of blood clots. In this work we used engineered proteins with alterations in an important but highly disordered area of the molecule called αC-region and we provide direct evidence for the first time for how the absence of either the globular αC-domain, or the complete αC-region impacts the mechanical behaviour of individual fibrin fibres. Using these results we developed a new structural model of protofibril organisation within fibrin fibres that fully explains their strain stiffening, relatively low modulus and their high, largely variable, extensibility. [Display omitted] [ABSTRACT FROM AUTHOR]

Material handling tasks often lead to skeletal injury of workers. The whole-body static biomechanical modeling method based on virtual humans is the theoretical basis for analyzing the human factor index in the lifting process. This paper focuses on the study of humans' body static biomechanical model for virtual human ergonomics analysis: First, the whole-body static biomechanical model is constructed, which calculates the biomechanical data such as force and moment, average strength, and maximum hand load at human joints. Secondly, the prototype model test system is developed, and the real experiment environment is set up with the inertial motion capture system. Finally, the model reliability verification experiment and application simulation experiment are designed. The comparison results with the industrial ergonomic software show that the model is consistent with the output of the industrial ergonomic software, which proves the reliability of the model. The simulation results show that under the same load, the maximum joint load and the maximum hand load are strongly related to the working posture, and the working posture should be adjusted to adapt to the load. Upright or bent legs have less influence on the maximum load capacity of the hand. Lower hand load capacity is due to forearm extension, and the upper arm extension greatly reduces the load capacity of the hand. Compared with a one-handed load, the two-handed load has a greater load capacity. [ABSTRACT FROM AUTHOR]

Revision total hip arthroplasty (rTHA) involving acetabular defects is a complex procedure associated with lower rates of success than primary THA. Computational modeling has played a key role in surgical planning and prediction of postoperative outcomes following primary THA, but modeling applications in rTHA for acetabular defects remain poorly understood. This study aimed to systematically review the use of computational modeling in acetabular defect classification, implant selection and placement, implant design, and postoperative joint functional performance evaluation following rTHA involving acetabular defects. The databases of Web of Science, Scopus, Medline, Embase, Global Health and Central were searched. Fifty‐three relevant articles met the inclusion criteria, and their quality were evaluated using a modified Downs and Black evaluation criteria framework. Manual image segmentation from computed tomography scans, which is time consuming, remains the primary method used to generate 3D models of hip bone; however, statistical shape models, once developed, can be used to estimate pre‐defect anatomy rapidly. Finite element modeling, which has been used to estimate bone stresses and strains, and implant micromotion postoperatively, has played a key role in custom and off‐the‐shelf implant design, mitigation of stress shielding, and prediction of bone remodeling and implant stability. However, model validation is challenging and requires rigorous evaluation and comparison with respect to mid‐ to long‐term clinical outcomes. Development of fast, accurate methods to model acetabular defects, including statistical shape models and artificial neural networks, may ultimately improve uptake of and expand applications in modeling and simulation of rTHA for the research setting and clinic. [ABSTRACT FROM AUTHOR]

This research introduces an innovative methodology for the integrated modeling, simulation, and analysis of two fingers, with particular emphasis on their fundamental roles in everyday tasks. In this study, we provide two nonlinear control strategies, specifically Sliding Mode Control (SMC) and Feedback Linearization Control (FLC), to achieve accurate and stable finger movements. As mentioned earlier, the controllers are utilized in the context of a biomechanical model consisting of two fingers, each possessing two degrees of freedom. These controllers enable the coordination of flexion and extension movements. The research conducted in our study emphasizes the coordinated regulation of finger movements, enabling the achievement of flexion through the utilization of two nonlinear controllers. By implementing these sophisticated control mechanisms, we can effectively showcase our model's fidelity in adhering to the physiological limitations inherent to human fingers in their natural state. In addition, the proposed controllers demonstrate sound mitigation of non-linearities, such as load variations, different velocities, positional changes, and damping forces. This approach presents several advantages, such as handling non-linearities, guaranteeing robustness, choosing suitable parameters, and conducting comparative analysis. In order to substantiate our findings, we develop the nonlinear model utilizing the MATLAB/Simulink software. The findings of our study demonstrate effective regulation and control of the two-finger model's position. In our study, we were able to get flexion angles of θ 1 = 1. 221 rad and θ 2 = 1. 396 rad using the sliding mode control (SMC) technique, and flexion angles of θ 1 = 1. 047 rad and θ 2 = 1. 134 rad using the fuzzy logic control (FLC) technique, all within a time frame of 5 s. These results serve to illustrate the applicability and significance of our proposed methodology. [ABSTRACT FROM AUTHOR]

We present a comprehensive neural network to model the deformation of human soft tissues including muscle, tendon, fat and skin. Our approach provides kinematic and active correctives to linear blend skinning [Magnenat-Thalmann et al. 1989] that enhance the realism of soft tissue deformation at modest computational cost. Our network accounts for deformations induced by changes in the underlying skeletal joint state as well as the active contractile state of relevant muscles. Training is done to approximate quasistatic equilibria produced from physics-based simulation of hyperelastic soft tissues in close contact. We use a layered approach to equilibrium data generation where deformation of muscle is computed first, followed by an inner skin/fascia layer, and lastly a fat layer between the fascia and outer skin. We show that a simple network model which decouples the dependence on skeletal kinematics and muscle activation state can produce compelling behaviors with modest training data burden. Active contraction of muscles is estimated using inverse dynamics where muscle moment arms are accurately predicted using the neural network to model kinematic musculotendon geometry. Results demonstrate the ability to accurately replicate compelling musculoskeletal and skin deformation behaviors over a representative range of motions, including the effects of added weights in body building motions. [ABSTRACT FROM AUTHOR]

The Latarjet procedure is an established surgical treatment for recurrent glenohumeral joint instability with glenoid bone loss. Intraoperatively, the conjoint tendon and its attachement on the coracoid bone graft is routed through a split in subscapularis where the graft is fixed to and augments the anteroinferior glenoid. The objective of this in vitro study was to quantify the influence of glenohumeral joint position and conjoint tendon force on the lines of action and moment arms of subscapularis muscle sub‐regions after Latarjet surgery. Eight fresh‐frozen, entire upper extremities were mounted onto a testing apparatus, and a cable‐pulley system was used to apply physiological muscle loading to the major shoulder muscles. The lines of action and moment arms of four subregions of subscapularis (superior, mid‐superior, mid‐inferior, and inferior) were quantified radiographically with the conjoint tendon unloaded and loaded while the shoulder was in (i) 0° abduction (ii) 90° abduction (iii) 90° abduction and full external rotation (ABER), and (iv) the apprehension position, defined as ABER with 30° horizontal extension. Conjoint tendon loading after Latarjet surgery significantly increased the inferior inclination of the lines of action of the mid‐inferior and inferior subregions of subscapularis in the scapular plane in ABER and apprehension positions (p < 0.001), as well as decreased the horizontal flexion moment arm of the inferior subscapularis (p = 0.040). Increased subscapularis inferior inclination may ultimately increase inferior joint shear potential, while smaller horizontal flexion leverage may reduce joint flexion capacity. The findings have implications for Latarjet surgical planning and postoperative rehabilitation prescription. [ABSTRACT FROM AUTHOR]

Total temporomandibular joint replacement (TMJR) surgery is the established treatment for severe temporomandibular joint disorders. While TMJR surgery is known to increase mouth-opening capacity, reduce pain and improve quality of life, little is known about post-surgical jaw function during activities of daily living such as biting and chewing. The aim of this study was to use subject-specific 3D bite force measurements to evaluate the magnitude and direction of joint loading in unilateral total TMJR patients and compare these data to those in healthy control subjects. An optoelectronic tracking system was used to measure jaw kinematics while biting a rubber sample for 5 unilateral total TMJR patients and 8 controls. Finite element simulations driven by the measured kinematics were employed to calculate the resultant bite force generated when compressing the rubber between teeth during biting tasks. Subject-specific musculoskeletal models were subsequently used to calculate muscle and TMJ loading. Unilateral total TMJR patients generated a bite force of 249.6 ± 24.4 N and 164.2 ± 62.3 N when biting on the contralateral and ipsilateral molars, respectively. In contrast, controls generated a bite force of 317.1 ± 206.6 N. Unilateral total TMJR patients biting on the contralateral molars had a significantly higher lateral TMJ force direction (median difference: 63.6°, p = 0.028) and a significantly lower ratio of working TMJ force to bite force (median difference: 0.17, p = 0.049) than controls. Results of this study may guide TMJ prosthesis design and evaluation of dental implants. [ABSTRACT FROM AUTHOR]

Dual-task walking and cell phone usage, which is associated with high cognitive load and reduced situational awareness, can increase risk of a collision, a fall event, or death. The objective of this study was to quantify the effect of dual-task cell phone talking, texting, and reading while walking on spatiotemporal gait parameters; minimum foot clearance; and dynamic stability of the lower limb joints, trunk, and head. Nineteen healthy male participants walked on an instrumented treadmill at their self-selected speed as well as walking while simultaneously (1) reading on a cell phone, (2) texting, and (3) talking on a cell phone. Gait analyses were performed using an optical motion analysis system, and dynamic stability was calculated using the Maximum Lyapunov Exponent. Dual-task cell phone usage had a significant destabilizing influence on the lower limb joints during walking. Cell phone talking while walking significantly increased step width and length and decreased minimum foot clearance height (P <.05). The findings suggest that dual-task walking and cell phone conversation may present a greater risk of a fall event than texting or reading. This may be due to the requirements for more rapid information processing and cognitive demand at the expense of motor control of joint stability. [ABSTRACT FROM AUTHOR]

This article explains the mechanics, control strategies and main applications of a new concept which achieves a balance between energy saving and driver comfort. A physical and mathematical model of a suspension system with energy recovery is presented. It shows practical implementation of the BLDC braking system with energy recovery in a horizontal seat suspension and a detailed simulation analysis of their features and performance. The research involves a specific solution, with a specific BLDC motor, and experimental tests on a laboratory stand. The results of the simulation study using a simplified biomechanical model and experimental studies with human participation are presented. [ABSTRACT FROM AUTHOR]

Subacromial impingement (SAI) is associated with shoulder pain and dysfunction and is exacerbated by rotator cuff tears; however, the role of acromioplasty in mitigating subacromial contact in the rotator cuff deficient shoulder remains debated. This study aimed to quantify the influence of isolated and combined tears involving the supraspinatus on subacromial contact during abduction; and second, to evaluate the influence of acromioplasty on joint space size and subacromial contact under these pathological conditions. Eight fresh‐frozen human cadaveric upper limbs were mounted to a computer‐controlled testing apparatus that simulated joint motion by simulated force application. Shoulder abduction was performed while three‐dimensional joint kinematics was measured using an optoelectronic system, and subacromial contact evaluated using a digital pressure sensor secured to the inferior acromion. Testing was performed after an isolated tear to the supraspinatus, as well as tears involving the subscapularis and infraspinatus‐teres minor, both before and after acromioplasty. Rotator cuff tears significantly increased peak subacromial pressure (p < 0.001), average subacromial pressure (p = 0.001), and contact force (p = 0.034) relative to those in the intact shoulder. Following acromioplasty, significantly lower peak subacromial contact pressure, force and area were observed for all rotator cuff tears involving the supraspinatus at 30° of abduction (p < 0.05). Acromioplasty predominantly reduces acromion thickness anteriorly thereby reducing subacromial contact in the rotator cuff deficient shoulder, particularly in early to mid‐abduction where superior glenohumeral joint shear force potential is large. These findings provide a biomechanical basis for acromioplasty as an intervention for SAI syndrome and as an adjunct to rotator cuff repairs. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANNs) are a powerful class of computational models for unravelling neural mechanisms of brain function. However, for neural control of movement, they currently must be integrated with software simulating biomechanical effectors, leading to limiting impracticalities: (1) researchers must rely on two different platforms and (2) biomechanical effectors are not generally differentiable, constraining researchers to reinforcement learning algorithms despite the existence and potential biological relevance of faster training methods. To address these limitations, we developed MotorNet, an open-source Python toolbox for creating arbitrarily complex, differentiable, and biomechanically realistic effectors that can be trained on user-defined motor tasks using ANNs. MotorNet is designed to meet several goals: ease of installation, ease of use, a high-level user-friendly application programming interface, and a modular architecture to allow for flexibility in model building. MotorNet requires no dependencies outside Python, making it easy to get started with. For instance, it allows training ANNs on typically used motor control models such as a two joint, six muscle, planar arm within minutes on a typical desktop computer. MotorNet is built on PyTorch and therefore can implement any network architecture that is possible using the PyTorch framework. Consequently, it will immediately benefit from advances in artificial intelligence through PyTorch updates. Finally, it is open source, enabling users to create and share their own improvements, such as new effector and network architectures or custom task designs. MotorNet’s focus on higher-order model and task design will alleviate overhead cost to initiate computational projects for new researchers by providing a standalone, ready-to-go framework, and speed up efforts of established computational teams by enabling a focus on concepts and ideas over implementation.

Objective Participation in martial arts such as Karate, Taekwondo, Kung Fu, and Wushu has increased recently, and it is possible that determining the difference between performing different kicks in skilled athletes can be of great help to coaches and beginner athletes for better performance and prevention of sports injuries. Methods Twelve athletes in two fields of Taekwondo and Wushu were divided into groups of six people. A motion analysis device was used to measure the variables of roundhouse kicking with the foot. Paired t-tests were used to analyze the data at a significance level of 0.05 for statistical analysis. Results Findings showed that there is no significant difference between the duration of the kicking (leg return), the maximum speed of the foot until the moment of kicking, the speed of the foot at the moment of strike, the angle of the knee at the moment of strike, and thigh internal rotation angle (p>0.05). However, significant differences were observed in the variables of maximum knee angle in the flexion axis, hip flexion angle at the moment of strike, lateral angle (Y&Z) of the thigh at the moment of strike, the amount of internal rotation of the hip (in terms of angle), the amount of lateral rotation to the outside of the hip, the maximum amount of internal angular changes of the thigh in terms of time, and maximum amount of hip lateral angular changes in terms of time (p

The aim of this paper is to present theoretical aspects of the study of biomechanics in athletics, which is essential for performance optimization, injury prevention, and improvement of athletes' capabilities. This study contains various research directions in athlete biomechanics as well as biodynamic modeling and simulation in athletics. Finally, aspects of athlete training design and optimization are presented, which are essential for tailoring training programs to the individual needs and goals of athletes.

Material handling tasks often lead to skeletal injury of workers. The whole-body static biomechanical modeling method based on virtual humans is the theoretical basis for analyzing the human factor index in the lifting process. This paper focuses on the study of humans’ body static biomechanical model for virtual human ergonomics analysis: First, the whole-body static biomechanical model is constructed, which calculates the biomechanical data such as force and moment, average strength, and maximum hand load at human joints. Secondly, the prototype model test system is developed, and the real experiment environment is set up with the inertial motion capture system. Finally, the model reliability verification experiment and application simulation experiment are designed. The comparison results with the industrial ergonomic software show that the model is consistent with the output of the industrial ergonomic software, which proves the reliability of the model. The simulation results show that under the same load, the maximum joint load and the maximum hand load are strongly related to the working posture, and the working posture should be adjusted to adapt to the load. Upright or bent legs have less influence on the maximum load capacity of the hand. Lower hand load capacity is due to forearm extension, and the upper arm extension greatly reduces the load capacity of the hand. Compared with a one-handed load, the two-handed load has a greater load capacity.

Despite its high-level of robustness and versatility, the human sensorimotor control system regularly encounters and manages various noises, nonlinearities, uncertainties, redundancies, and delays. These delays, which are critical to biomechanical stability, occur in various parts of the system and include sensory, signal transmission, CNS processing, as well as muscle activation delays. Despite the relevance of accurate estimation and prediction of the various time delays, the current literature reflects major discrepancy with regards to existing prediction and estimation methods. This scoping review was conducted with the aim of characterizing and categorizing various approaches for estimation of physiological time delays based on PRISMA guidelines. Five data bases (EMBASE, PubMed, Scopus, IEEE and Web of Science) were consulted between the years of 2000 and 2022, with a combination of four related categories of keywords. Scientific articles estimating at least one physiological time delay, experimentally or through simulations, were included. Eventually, 46 articles were identified and analyzed with 20 quantification and 16 qualification questions by two separate reviewers. Overall, the reviewed studies, experimental and analytical, employing both linear and non-linear models, reflected heterogeneity in the definition of time delay and demonstrated high variability in experimental protocols as well as the estimation of delay values. Most of the summarized articles were classified in the high-quality category, where multiple sound analytical approaches, including optimization, regression, Kalman filter and neural network in time domain or frequency domain were used. Importantly, more than 50% of the reviewed articles did not clearly define the nature of the estimated delays. This review presents and summarizes these issues and calls for a standardization of future scientific works for estimation of physiological time-delay. [ABSTRACT FROM AUTHOR]

Purpose: The acquisition of good quality ultrasound (US) images requires good acoustic coupling between the ultrasound probe and the patient's skin. In practice, this good coupling is achieved by the operator applying a force to the skin through the probe. This force induces a deformation of the tissues underlying the probe. The distorted images deteriorate the quality of the reconstructed 3D US image. Methods: In this work, we propose two methods to correct these deformations. These methods are based on the construction of a biomechanical model to predict the mechanical behavior of the imaged soft tissues. The originality of the methods is that they do not use external information (force or position value from sensors, or elasticity value from the literature). The model is parameterized thanks to the information contained in the image. This is allowed thanks to the optimization of two key parameters for the model which are the indentation d and the elasticity ratio α. Results: The validation is performed on real images acquired on a gelatin-based phantom using an ultrasound probe inducing an increasing vertical indentation using a step motor. The results showed a good correction of the two methods for indentations less than 4 mm. For larger indentations, one of the two methods (guided by the similarity score) provides a better quality of correction, presenting a Euclidean distance between the contours of the reference image and the corrected image of 0.71 mm. Conclusion: The proposed methods ensured the correction of the deformed images induced by a linear probe pressure without using any information coming from sensors (force or position), or generic information about the mechanical parameters. The corrected images can be used to obtain a corrected 3D US image. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present theoretical aspects of the study of biomechanics in athletics, which is essential for performance optimization, injury prevention, and improvement of athletes' capabilities. This study contains various research directions in athlete biomechanics as well as biodynamic modeling and simulation in athletics. Finally, aspects of athlete training design and optimization are presented, which are essential for tailoring training programs to the individual needs and goals of athletes. [ABSTRACT FROM AUTHOR]

Inertial measurement units (IMUs) have been validated for measuring sagittal plane lower-limb kinematics during moderate-speed running, but their accuracy at maximal speeds remains less understood. This study aimed to assess IMU measurement accuracy during high-speed running and maximal effort sprinting on a curved non-motorized treadmill using discrete (Bland–Altman analysis) and continuous (root mean square error [RMSE], normalised RMSE, Pearson correlation, and statistical parametric mapping analysis [SPM]) metrics. The hip, knee, and ankle flexions and the pelvic orientation (tilt, obliquity, and rotation) were captured concurrently from both IMU and optical motion capture systems, as 20 participants ran steadily at 70%, 80%, 90%, and 100% of their maximal effort sprinting speed (5.36 ± 0.55, 6.02 ± 0.60, 6.66 ± 0.71, and 7.09 ± 0.73 m/s, respectively). Bland–Altman analysis indicated a systematic bias within ±1° for the peak pelvic tilt, rotation, and lower-limb kinematics and −3.3° to −4.1° for the pelvic obliquity. The SPM analysis demonstrated a good agreement in the hip and knee flexion angles for most phases of the stride cycle, albeit with significant differences noted around the ipsilateral toe-off. The RMSE ranged from 4.3° (pelvic obliquity at 70% speed) to 7.8° (hip flexion at 100% speed). Correlation coefficients ranged from 0.44 (pelvic tilt at 90%) to 0.99 (hip and knee flexions at all speeds). Running speed minimally but significantly affected the RMSE for the hip and ankle flexions. The present IMU system is effective for measuring lower-limb kinematics during sprinting, but the pelvic orientation estimation was less accurate. [ABSTRACT FROM AUTHOR]

• Firefighter-specific musculoskeletal models were developed to quantify loads. • Carrying SCBA increased firefighters' rectus femoris force, hip and knee exertion. • Adjusting shoulder strap length is an effective ergonomic intervention. • Targeting physical training at firefighters' lower limb is suggested. • Compatibility design of the trunk morphology and back-mounted frame is needed. Introduction : Musculoskeletal loading data are needed to design ergonomic intervention for firefighters. This study aimed to quantify the firefighters' musculoskeletal loads during self-contained breathing apparatus (SCBA) carriage and evaluate the effectiveness of shoulder strap length variation for the prevention of SCBA-related injuries. Method: Twelve firefighters (height: 174.6 ± 2.4 cm, mass: 67 ± 3.5 kg, BMI = 22 ± 1 kg/m2) participated the walking and running protocols with no SCBA equipped and three varying-strapped SCBAs conditions. Joint range of motion and surface electromyography (sEMG) were synchronously measured. Subsequently, joint kinematics was inputted for subject-specific musculoskeletal modeling to estimate muscle forces and joint reaction forces, while the sEMG was used to validate the model. Repeated measures analysis of variance was used for the main effects (p < 0.05). Independent samples t -test was performed to determine differences between walking and running. Results: Walking with SCBA increased the rectus femoris force and hip reaction force by 34.92% [ F = 53.629; p < 0.001; η2 = 0.317] and 34.71% [ F = 53.653; p < 0.001; η2 = 0.517], the growth rate was 54.2% [ F = 76.487; p < 0.001; η2 = 0.418] and 51.19% [ F = 69.201; p < 0.001; η2 = 0.652] during running, respectively. Running with SCBA significantly increased the knee reaction force by 63.04% [ F = 83.960; p < 0.001; η2 = 0.797], while only 18.49% increase during walking. Adjusting SCBA shoulder strap length significantly altered the rectus abdominis force and L4/L5 reaction force during walking and running. Conclusions: Results revealed that rectus femoris activity, hip and knee exertion was sensitive to SCBA carriage. The variation of shoulder strap length has potential to influence the risk of low back pain (LBP). Practical applications: The findings suggest that fire services promote targeting physical training at firefighters' hip and knee regions. Test firefighters in this study were not advisable to adjust their shoulder strap at loose-fitting condition. The compatibility design of the trunk morphology and SCBA back-mounted frame was suggested for the management of LBP. [ABSTRACT FROM AUTHOR]

Musculoskeletal biomechanical models have wide applications in ergonomics, rehabilitation, and injury estimation. Their use can be extended to enable quantitatively explaining and estimating ride comfort for a vehicle's passenger. A biomechanical model of the upper body in the sagittal plane is constructed, which allows for curved motion to simulate the propagation of disturbance energy within a seated passenger aboard a moving vehicle. The dynamic predictions of the model are validated against experimental results within the literature. Frequency responses show that within the vehicular frequency range, the L4L5 and the L5S1 discs in the lower lumbar region are susceptible to the highest vibration transmission. It was also found that vibration transmission is maximized at around 4.5 Hz. The model provides analytical and geometric intuition into the motion of the various segments of the upper body using a few simple geometric assumptions and can be employed to develop a quantitative ride-comfort metric, such that the most comfortable ride would be that which would induce the least internal motion within the passenger model.

Despite its high-level of robustness and versatility, the human sensorimotor control system regularly encounters and manages various noises, non-linearities, uncertainties, redundancies, and delays. These delays, which are critical to biomechanical stability, occur in various parts of the system and include sensory, signal transmission, CNS processing, as well as muscle activation delays. Despite the relevance of accurate estimation and prediction of the various time delays, the current literature reflects major discrepancy with regards to existing prediction and estimation methods. This scoping review was conducted with the aim of characterizing and categorizing various approaches for estimation of physiological time delays based on PRISMA guidelines. Five data bases (EMBASE, PubMed, Scopus, IEEE and Web of Science) were consulted between the years of 2000 and 2022, with a combination of four related categories of keywords. Scientific articles estimating at least one physiological time delay, experimentally or through simulations, were included. Eventually, 46 articles were identified and analyzed with 20 quantification and 16 qualification questions by two separate reviewers. Overall, the reviewed studies, experimental and analytical, employing both linear and non-linear models, reflected heterogeneity in the definition of time delay and demonstrated high variability in experimental protocols as well as the estimation of delay values. Most of the summarized articles were classified in the high-quality category, where multiple sound analytical approaches, including optimization, regression, Kalman filter and neural network in time domain or frequency domain were used. Importantly, more than 50% of the reviewed articles did not clearly define the nature of the estimated delays. This review presents and summarizes these issues and calls for a standardization of future scientific works for estimation of physiological time-delay.

Sit-Up tests have been involved to measure the abdominal strength and endurance of youth and elite players in training sessions and specific skill tests. This study was aimed at evaluating the fitness level of the muscular strength and endurance of the abdominal and hip-flexor muscles of youth people corresponding to the body segment parameters: height and weight. The test battery and biomechanical model of the dynamic movement of Sit-Up were designed. The 30s Sit-Up test was performed by youth people: n = 1373 male and n = 1160 female. The percentile method was used to distinguish the performance levels. The average numbers of Sit-Up of males and females are 17 (SD = 2.17) and 12 (SD = 1.98), respectively. University students (68), who have already tested their fitness levels (satisfactory level or above) of muscular strength and endurance of abdominal and hipflexor muscles by the Euro-fit test, were selected to show the validity of the test battery. Nearly 90% of students were at the average level or above relevant to the new Sit-Up test battery. The biomechanical model described the main active muscles' forces (Rectus Femoris: 0-900 N, Psoas 0-300 N, and Iliacus 0-295 N) and total mechanical energy expenditure (132.66 J: 70.72 J, 61.94 J concentric and eccentric movements, respectively; player: mass 67.5 kg and height 1.66 m) for any player. The new '30s Sit-Up test battery' is affective to evaluate reliable fitness levels for muscular strength, endurance of abdominal and hip-flexor muscles of youth. The biomechanical model demonstrates the energy expenditure for anyone (EAvg = 0.317 + 0.002 Cal). [ABSTRACT FROM AUTHOR]

IntroductionArthrodesis, performed as a salvage surgical procedure to treat intractable joint conditions in dogs and cats, is associated with a high incidence of complications intra and postoperative, proving the need for improved and new techniques in arthrodesis surgery. Adding a new resorbable bone glue to the arthrodesis could potentially add fixation strength and lower complications. The objectives of this experimental ex vivo biomechanical study were therefore to develop a biomechanical test model of partial tarsal arthrodesis and to determine whether the new resorbable bone glue (phosphoserine modified cement) produced measurable fixation strength in canine calcaneoquartal arthrodesis, without orthopedic implants.MethodsFour biomechanical test models with a total of 35 canine tarsal joints were used. Soft tissues were dissected to 4 different test models with variable contributions from soft tissues. The calcaneoquartal joint was prepared as in vivo arthrodesis and the glue was applied to joint surfaces as a liquid/putty (0.4 cc). After curing for 24 h, a shear force was applied to the joint (1 mm per minute) and the failure strength was recorded.ResultsCalcaneoquartal joints, where all soft tissues had been completely resected and fixated with glue (1–1.5 cm2 joint surface), withstood 2–5 mm of displacement and an average of 100 ± 58 N/cm2 of shear force (Model 1). Similar adhesive fixation strengths were obtained in Model 2 and 3 with increasing contributions from soft tissues (80 ± 44 and 63 ± 23 N/cm2, p = 0.39, ANOVA).ConclusionThe developed biomechanical model was sensitive enough to measure differences in fixation strengths between different glue formulations. The average fixation strength (60–100 N/cm2) should be strong enough to support short-term load bearing in medium sized canines (20 kg). The developed cadaver biomechanical test model is of potential use for other arthrodesis studies. The new resorbable glue can potentially contribute to stability at arthrodesis surgery, acting as a complement to today’s standard fixation, metal implants.

Objective: The aim was to review the biomechanical origins of occupational shoulder damage, while considering the complexity of shoulder mechanics and musculoskeletal consequences of diverse task demands. Background: Accessible measures of physical exposures are the primary focus of occupational shoulder assessments and analyses. This approach has led to guidelines and intervention strategies that are often inadequate for mitigating shoulder disorders amongst the complexity of modern workplace demands. Integration of complex shoulder mechanics into occupational assessments, analyses, and interventions is critical for reducing occupational shoulder injury risk. Method: This narrative review describes shoulder biomechanics in the context of common injury mechanisms and consequent injuries, with a particular focus on subacromial impingement syndrome. Several modulators of shoulder injury risk are reviewed, including fatigue, overhead work, office ergonomics considerations, and pushing and pulling task configurations. Results: Relationships between work requirements, muscular demands, fatigue, and biomechanical tissue loads exist. This review highlights that consideration of specific workplace factors should be integrated with our knowledge of the intricate arrangement and interpersonal variability of the shoulder complex to proactively evaluate occupational shoulder demands and exposures. Conclusion: A standard method for evaluating shoulder muscle exposures during workplace tasks does not exist. An integrated approach is critical for improved work design and prevention of shoulder tissue damage and accompanying disability. Application: This review is particularly relevant for researchers and practitioners, providing guidance for work design and evaluation for shoulder injury prevention by understanding the importance of the unique and complex mechanics of the shoulder. [ABSTRACT FROM AUTHOR]

Using the passive ankle exoskeleton to reduce the energy consumption of human walking has been proposed by many researchers; however, limited knowledge of the impact of walking with the PAE on the human body has been reported. This study was to quantify the changes in the joints' internal forces (JIFs) during assisted walking. The joint kinematic patterns must be studied as a priority, and then it was used as the input of dynamic analysis to obtain the changes of JIFs. Firstly, based on the developed human-PAE system, we simulated the PAE assisting humans walking over a series of ankle angles, and the simulation result was consistent with the experimental data that the walking angle of the ankle joint kept invariable during walking with the PAE. Furthermore, we found that the JIFs of the knee and ankle, calculated by the biomechanical modeling, decreased at different degrees. The changes in the JIFs indicated that while reducing the ankle moment of normal walking by PAE, it also brought lower JIFs. The results provided a new perspective for using the elastic elements to assist human body movement, which reduces the JIFs of humans when assisting humans walking with an elastic ankle exoskeleton. To study the influence of the passive ankle exoskeleton on the human joints' internal forces. We established the dynamics model of the human joints' internal forces and presented the highly human-machine compatible design and finished the relative tests. In the experimental, we found that the human joints' internal forces increased at different degrees. Besides, the joints' angle of the human lower limb kept invariable, which was consistent with the simulation analysis of walking with the passive ankle exoskeleton, when the spring stiffness of the matching experimenter was the best. In the figure, the red line represents the internal force of the human knee joint and the yellow line represents the internal force of the human ankle joint. In the late stance phase although the coordinated movement of the human-PAE system and the reduction of the human ankle moment, the internal forces of the human knee and ankle joint increased because of the forces of the stretched spring acting on the human ankle and knee joint. [ABSTRACT FROM AUTHOR]

This research paper aimed to validate two methods for measuring loads during walking with instrumented crutches: one method to estimate partial weight-bearing on the lower limbs and another to estimate shoulder joint reactions. Currently, gait laboratories, instrumented with high-end measurement systems, are used to extract kinematic and kinetic data, but such facilities are expensive and not accessible to all patients. The proposed method uses instrumented crutches to measure ground reaction forces and does not require any motion capture devices or force platforms. The load on the lower limbs is estimated by subtracting the forces measured by the crutches from the subject's total weight. Since the model does not consider inertia contribution in dynamic conditions, the estimation improves with low walking cadence when walking with the two-point contralateral and the three-point partial weight-bearing patterns considered for the validation tests. The shoulder joint reactions are estimated using linear regression, providing accurate values for the forces but less accurate torque estimates. The crutches data are acquired and processed in real-time, allowing for immediate feedback, and the system can be used outdoors in real-world walking conditions. The validation of this method could lead to better monitoring of partial weight-bearing and shoulder joint reactions, which could improve patient outcomes and reduce complications. [ABSTRACT FROM AUTHOR]

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BackgroundReactive lower limb muscle function during walking plays a role in balance, stability, and ultimately fall prevention. The objective of this study was to evaluate muscle and joint function used to regain balance after trip-based perturbations during walking.Research questionHow are lower limb muscles used to recover from external tripping during walking?MethodThe dominant legs of 20 healthy adult participants with similar athletic backgrounds were tripped using a split-belt instrumented treadmill. High- and medium-intensity trips were simulated by deceleration of the dominant leg at initial contact from the speed of 1.1 m/s to 0 m/s and back to 1.1 m/s in 0.4 s and 0.8 s, respectively. Lower limb kinematics, kinetics, and muscle forces following perturbations were computed to pre-perturbation values using statistical parametric mapping (SPM) paired t-test.ResultsA greater ankle dorsiflexion angle (mean difference: 5.3°), ankle plantar flexion moment (mean difference: 0.6Nm/kg), and gastrocnemius and soleus muscle forces (mean difference: 4.27N/kg and 13.56N/kg for GAS and SOL, respectively) were observed post-perturbation step despite the magnitude of the perturbation.SignificanceThis study concludes that adequate timely response of ankle function during a compensatory step is required for a successful recovery after tripping during walking in young healthy adults. Weakness in plantar flexors suggests insufficient ankle moments, which ultimately can result in falls. The findings of this paper can be used as a reference for the joint moments and range of motion needed to recover trips in the design of assistive devices. In addition to that, clinicians can use the estimated values of muscle forces and the pattern of muscle activities to design targeted training in fall prevention among the elderly.

The left ventricle (LV) has an important mechanical part in pumping blood throughout the body and it is generally sensitive to the failure. Heart failure is one of the world's leading causes of death and has reached the epidemic rate. For the study of heart failure, there are several diagnostic methods, but computational biomechanical models of human myocardium would be a practical tool in diagnostics and patient specific treatment planning. These models help in classifying myocardium pathologies. In this paper, we developed a quasi-static biomechanical model of the LV for healthy subjects based on Cardiac Magnetic Resonance (CMR) acquisition. Estimation LV strain is done using Finite Element (FE) software Abaqus and clinical assessment measured from 20 healthy subjects, such as End Systole (ES) and End Diastole (ED) volumes, ED wall thickness and wall thickening. We acquired LV End Systole strain component is within one standard deviation of the measurements made in the equatorial region of LV. The results of this study suggest that the proposed FE model of LV describes the physiological function of the heart and can differentiate between normal and pathological cardiac function. [ABSTRACT FROM AUTHOR]

Cardiac cine magnetic resonance (CCMR) imaging plays an important role in the clinical cardiovascular disease (CVD) examination and evaluation.To accurately reconstruct the displacement field and describe the motion of the left ventricular myocardium (LVM), this study proposes and tests a new approach for tracking myocardial motion of the left ventricle based on a biomechanical model.CCMR imaging data acquired from 103 patients are enrolled, including two simulated and 101 clinical data. A non-rigid image registration method with a combination of a thin-plate spline function and random sample consensus is used to recover the observed displacement field of LVM. Next, a biomechanical model and a material matrix are introduced to solve the dense displacement field of LVM using a finite element framework. Then, the tracking precision and error of results for the two groups are analyzed.Displacement results of the simulated data show correlation coefficient≥0.876 and mean square error≤0.159, while displacement results of the clinical data show Dice≥0.97 and mean contour distance≤0.464. Additionally, the strain results show correlation coefficient≥0.717.This study demonstrates that the proposed new method enables to accurately track the motion of the LVM and evaluate strain, which has clinical auxiliary value in the diagnosis of CVD. [ABSTRACT FROM AUTHOR]

Numerical models of the musculoskeletal system as investigative tools are an integral part of biomechanical and clinical research. While finite element modeling is primarily suitable for the examination of deformation states and internal stresses in flexible bodies, multibody modeling is based on the assumption of rigid bodies, that are connected via joints and flexible elements. This simplification allows the consideration of biomechanical systems from a holistic perspective and thus takes into account multiple influencing factors of mechanical loads. Being the source of major health issues worldwide, the human spine is subject to a variety of studies using these models to investigate and understand healthy and pathological biomechanics of the upper body. In this review, we summarize the current state-of-the-art literature on multibody models of the thoracolumbar spine and identify limitations and challenges related to current modeling approaches. [ABSTRACT FROM AUTHOR]

Nachdem in Teil 1 des Beitrags im vorigen Heft ein deutlicher Bedarf für einen kohärenten, interprofessionellen und metakonzeptionellen Rahmen für die osteopathische Versorgung nachgewiesen wurde, wird im 2. Teil des Hypothesenpapiers die Integrale Theorie (IT) als ein ganzheitlicher, evidenzbasierter, multimodaler, selbstreflexiver klinischer Argumentationsprozess vorgeschlagen und aufgezeigt, wie die verschiedenen osteopathischen Versorgungsmodelle in das Vier-Quadranten-Modell der IT eingefügt werden können. Die Integrale Theorie findet beispielsweise im Rahmen der psychosomatischen Osteopathie ihre Anwendung, bei der auch die spirituelle Komponente des Seins beleuchtet wird, um Patient*innen innerhalb ihres gesamten Lebenskontexts zu behandeln. So können beim Menschen in jedem dieser – von der Befruchtung bis zum Tod reichenden – Entwicklungsschritte und Morphodynamiken mögliche schädliche oder belastende externe oder interne Einflüsse auftreten, die zu Befindensstörungen, Symptomen und zu somatisch-energetisch-psychischen Dysfunktionsmustern führen können. Having demonstrated a clear need for a coherent, interprofessional, and metaconceptual framework for osteopathic care in part 1 in the previous issue, part 2 of this hypothesis paper proposes Integral Theory (IT) as a holistic, evidence-based, multimodal, self-reflexive clinical reasoning process and shows how the different osteopathic models of care can be integrated into the 4-quadrant model of IT. This is used, for example, in the context of psychosomatic osteopathy, where the spiritual component of being is also taken into account in order to treat patients within their whole life context. Thus, in humans, in each of these developmental steps and morphodynamics – from conception to death – possibly harmful or stressful external or internal influences may occur, which can lead to disorders of well-being, symptoms and to somatic-energetic-psychic dysfunctional patterns. [ABSTRACT FROM AUTHOR]

This paper proposes a biomechanical platelet model with an intracellular prestressed assumption. The platelet structure is composed of a membrane cortex and a marginal band (MB). The membrane cortex is assumed in a spherical shape in its initial state and modeled using spring-network elements widely used for the similar membrane structure of red blood cells. The MB is modeled as one solid torus, which employs the hyperelastic material model, and is confined inside the cortex through a contact model. In the initial equilibrium state, the platelet has a stable, flat, and discoid shape. Upon activation, the possible mechanism of the unbinding rate of crosslink between the microtubules (MTs) is assumed to break the homogeneous stiffness of the MB, which causes the platelet to have a disc-to-sphere morphological transition. The numerical results and the experimental images of the MBs show good agreement. The proposed model provides a novelty in relating the mechanical property changes of the MB to the platelet morphological changes upon activation, thus, can provide a possible engineering tool to reveal the intriguing behavior of platelet upon activation. [ABSTRACT FROM AUTHOR]

The left myocardium is the strongest cardiac muscle, representing the ability of heart to pump arterial blood throughout the body. Quantitative analysis of the contractive motion of left ventricle (LV) stands an important approach to diagnose cardiovascular diseases such as myocardial infarction. This paper utilized a biomechanical model describing the material of left myocardium to reconstruct the displacement field of LV. The mechanical model was used as an interpolation term, which was incorporated into the Bayesian estimation framework with the displacement field observed by cardiac cine magnetic resonance (CCMR) image, and the equation of displacement field was solved by finite element method. Functional parameters of LV were compared between the weak (46 cases) and normal (55 cases) ejection fraction groups of LV in the experiment. Significant differences in radial and circumferential displacement and velocity, strain and strain rate were observed between the two groups (p < 0.001), which proved that the method could effectively distinguish whether the motion of LV is normal or not. The experimental results are also highly correlated with the functional parameters of LV measured by CVI software, indicating that the method will facilitate the diagnosis of cardiovascular diseases.

Windsurfing sails have three degrees of controllable angular freedoms and rely heavily on the sailor's gravity to balance the heeling moments. The position of the sailor's center of gravity that affect the moment generation is greatly influenced by the posture. These factors result in the complexity of predicting windsurfing velocity during steady sailing, which is shown to be an under-defined problem. To address the challenges, this study proposes a hierarchical approach. At the lower levels of the hierarchy, a mechanical model of windsurfing is constructed by incorporating a tailor-made biomechanical model of the sailor, as well as the aero- and hydrodynamic properties of the sail, board, and sailor. The mechanical model allows the investigation of control variables that lead to different steady states, including sail roll, yaw and hydrofoil roll. At a higher level, these variables are optimized to maximize sailing speed. The proposed approach provides intermediate results that explore factors affecting sailing velocity, such as sail and board orientation angles, the sailor's center of gravity, and wind conditions. Furthermore, the approach generates a velocity polar chart that illustrates the maximum sailing speed for different travel directions. The chart indicates the maximum VMG and optimal sailing angle for achieving an upwind or downwind mark. This study contributes to a deeper understanding of the critical variables influencing windsurfing velocity and provide insights for improving sailing performance. • A tailor-made biomechanical model was integrated into the VPP to consider the impact of sailor's posture on load. • A hierarchical approach was developed to address the under-defined problem of windsurfing velocity prediction. • The proposed VPP was validated through field test measurements using a developed sensor package. • The VPP evaluated some factors impacting sailing velocity and enable the creation of a velocity polar chart. [ABSTRACT FROM AUTHOR]

Many physically straining occupations involve lifting movements over the full-vertical range of motion, which over time may lead to the development of musculoskeletal injuries. To address this, occupational exoskeletons can be designed to provide meaningful support to the back and shoulders during lifting movements. This paper introduces the main functional design features of the OmniSuit, a novel passive occupational exoskeleton. We present the technical and biomechanical considerations for the expected support level, as well as an evaluation of the physiological benefit and usability of the exoskeleton in a sample of 31 healthy volunteers performing physically demanding tasks in a laboratory setting. The OmniSuit exoskeleton significantly reduced Deltoid, Trapezius and Erector Spinae muscle activity between 4.1%MVC and 15.7%MVC when lifting a 2.5 kg weight above shoulder level (p < 0.001), corresponding to a reduction of up to 49.1% compared to without exoskeleton. A position-dependent reduction of Erector Spinae muscle activity was observed (p < 0.001), with reductions ranging between 4.6%MVC and 14.0%MVC during leaning and squatting, corresponding to a reduction up to 41.5% compared to without exoskeleton. The measured muscular support and the predicted support torque based on the biomechanical model were found to show a similar profile for those phases of the movement which are most straining to the shoulder and back muscles. Participants reported experiencing good device usability and minimal discomfort (<1/10) in the shoulder and back during task execution with exoskeleton support. These first results validate that the considered biomechanical model helped design an ergonomic and efficient exoskeleton, and confirm the potential of such wearable assistive devices to provide support over multiple joints during physically demanding tasks. [Display omitted] [ABSTRACT FROM AUTHOR]

The construction of a rigid body biomechanical model with higher ordered controller design is a challenging task due to the complicated architecture and complexity of human intended movements. Biomechanical analysis of such complex model for sit-to-stand (STS) movement in three dimensions (3D) requires the envisioned actions of humans by utilizing motor controls. The current study aims to enhance our investigation into 3D bipedal mobility by creating optimal control for our novel Twist and Tilt foot mechanism. Unlike earlier models, this mechanism does not assume any fixed foot for the entire profile. This novel model type enables one foot to perform a twisting motion and the other foot to execute a sliding tilt motion. This technique simulates the control effort needed during the STS task by individuals with neurological impairments while performing various joint positions. The twist and tilt model is created using computer-aided design (CAD) software SOLIDWORKS, utilizing an 8-segment biped. The linearized model in SIMULINK generated 24th ordered State Space model. Subsequently, we developed LQR (linear quadratic regulator) controller for attaining the desired trajectories in MATLAB/SIMULINK. This novel twist and tilt optimal control strategy have improved angular profiles and simulation results showcase the stroke patient’s movements with one foot sliding deficient tilt and other foot twisting during the profile. [ABSTRACT FROM AUTHOR]

Abstract Background The ability to measure joint kinematics in natural environments over long durations using inertial measurement units (IMUs) could enable at-home monitoring and personalized treatment of neurological and musculoskeletal disorders. However, drift, or the accumulation of error over time, inhibits the accurate measurement of movement over long durations. We sought to develop an open-source workflow to estimate lower extremity joint kinematics from IMU data that was accurate and capable of assessing and mitigating drift. Methods We computed IMU-based estimates of kinematics using sensor fusion and an inverse kinematics approach with a constrained biomechanical model. We measured kinematics for 11 subjects as they performed two 10-min trials: walking and a repeated sequence of varied lower-extremity movements. To validate the approach, we compared the joint angles computed with IMU orientations to the joint angles computed from optical motion capture using root mean square (RMS) difference and Pearson correlations, and estimated drift using a linear regression on each subject’s RMS differences over time. Results IMU-based kinematic estimates agreed with optical motion capture; median RMS differences over all subjects and all minutes were between 3 and 6 degrees for all joint angles except hip rotation and correlation coefficients were moderate to strong (r = 0.60–0.87). We observed minimal drift in the RMS differences over 10 min; the average slopes of the linear fits to these data were near zero (− 0.14–0.17 deg/min). Conclusions Our workflow produced joint kinematics consistent with those estimated by optical motion capture, and could mitigate kinematic drift even in the trials of continuous walking without rest, which may obviate the need for explicit sensor recalibration (e.g. sitting or standing still for a few seconds or zero-velocity updates) used in current drift-mitigation approaches when studying similar activities. This could enable long-duration measurements, bringing the field one step closer to estimating kinematics in natural environments.

Functional electrical stimulation (FES) can be used to restore motor function to people with paralysis caused by spinal cord injuries (SCIs). However, chronically-paralyzed FES-stimulated muscles can fatigue quickly, which may decrease FES controller performance. In this work, we explored the feasibility of using deep neural network (DNN) controllers trained with reinforcement learning (RL) to control FES of upper-limb muscles after SCI. We developed upper-limb biomechanical models that exhibited increased muscle fatigability, decreased muscle recovery, and decreased muscle strength, as observed in people with chronic SCIs. Simulations confirmed that controller training time and controller performance are impaired to varying degrees by muscle fatigability. Also, the simulations showed that large muscle strength asymmetries between opposing muscles can substantially impair controller performance. However, the results of this study suggest that controller performance for highly-fatigable musculoskeletal systems can be preserved by allowing for rest between movements. Overall, the results suggest that RL can be used to successfully train FES controllers, even for highly-fatigable musculoskeletal systems.

Featured Application: This study presents a new method to estimate the residual forces (tones) of the trunk muscles at rest, including the deep ones that are difficult to reach with nonintrusive means. Compared to classical methods (intrusive means), this method is painless and safe for the subject, as it uses only trunk experimental stiffness in conjunction with numerical modeling. The present method can be used independently or to supplement classical means which provide direct measures for the tone of superficial muscles. With these measures the identification problem is reduced to finding the tones of only the deep muscles. The proposed method can then be applied, for the specific subject with further gain in accuracy and efficiency. The accuracy of results can be improved by considering more muscle classes in the identification methodology. This work proposes an identification methodology to estimate the residual tension values (tones) for the human trunk muscles, including the deep ones, using multidirectional trunk stiffness data in association with numerical modeling. The role of this residual muscle tension or contraction is to maintain posture and balance. Knowledge of the tone is useful for the diagnosis and treatment of several spinal diseases and is important for realistic modeling and numerical simulation of trunk behavior. Most of the existing techniques for the measurement and estimation of muscle tones, such as electromyography, are restricted to superficial muscles. Those designed for deep muscles are invasive and present risks of infection and pain. In contrast, the proposed identification approach is painless and safe for the subject. It proceeds by matching the experimental trunk stiffness with numerical upper and lower estimates of the stiffness, to construct an inclusive solution domain of possible tone values of superficial as well as deep trunk muscles. By dividing the trunk muscles into three classes, each assumed to share the same tone ratio, a reasonable solution domain is obtained that exhibits a significant overlap with ranges of muscle tones found in the literature. [ABSTRACT FROM AUTHOR]

In recent years, myoelectric control systems have emerged for upper limb wearable robotic exoskeletons to provide movement assistance and/or to restore motor functions in people with motor disabilities and to augment human performance in able-bodied individuals. In myoelectric control, electromyographic (EMG) signals from muscles are utilized to implement control strategies in exoskeletons and exosuits, improving adaptability and human–robot interactions during various motion tasks. This paper reviews the state-of-the-art myoelectric control systems designed for upper-limb wearable robotic exoskeletons and exosuits, and highlights the key focus areas for future research directions. Here, different modalities of existing myoelectric control systems were described in detail, and their advantages and disadvantages were summarized. Furthermore, key design aspects (i.e., supported degrees of freedom, portability, and intended application scenario) and the type of experiments conducted to validate the efficacy of the proposed myoelectric controllers were also discussed. Finally, the challenges and limitations of current myoelectric control systems were analyzed, and future research directions were suggested. [ABSTRACT FROM AUTHOR]

Das Konzept der fünf osteopathischen Modelle (biomechanisch, neurologisch, zirkulatorisch-respiratorisch, metabolisch und psychisch) wurde auf der Grundlage der Prinzipien der Osteopathie entwickelt und wird gegenwärtig von vielen Osteo-path*innen als Basis für die klinische Anwendung der osteopathischen Prinzipien genutzt. Dennoch wird innerhalb der osteopathischen Gemeinschaft nach einem Konsens über einen theoretischen Metarahmen für die osteopathische Versorgung gesucht. Innerhalb dieser Debatte werden biopsychosoziale und biomechanisch-strukturelle Ansätze postuliert, welche häufig als gegensätzlich und nicht komplementär verstanden werden. Daraus zeichnet sich ein deutlicher Bedarf für einen kohärenten, interprofessionellen und metakonzeptionellen Rahmen für die osteopathische Versorgung ab. Im 2. Teil im kommenden Heft wird die Inte-grale Theorie (IT) als ein ganzheitlicher, evidenz-basierter, multimodaler, selbstreflexiver klinischer Argumentationsprozess vorgestellt und diskutiert. The concept of the five osteopathic models was developed on the basis of the principles of osteopathy and is currently used by many osteopaths as a basis for the clinical application of osteopathic principles. However, a consensus on a theoretical meta-framework for osteopathic care is being sought within the osteopathic community. Within this debate, biopsychosocial and biomechanical-structural approaches are postulated, which are often understood as opposing and not complementary. From this, a clear need for a coherent, interprofessional and metaconceptual framework for osteopathic care emerges. In part 2 in the upcoming issue, Integral Theory (IT) will be presented and discussed as a holistic, evidence-based, multimodal, self-reflexive clinical reasoning process. [ABSTRACT FROM AUTHOR]

Automatic venipuncture robots are expected to replace manual venipuncture methods owing to their high control precision, steady operation, and measurable perception. However, the lack of perception of the venipuncture status in the human body leads to an increased risk and failure rate, which further restricts the development of such robots. To address this, we propose a humanoid venipuncture method guided by a biomechanical model to imitate human sensations and feedback. This method intends to perceive the venipuncture status and improve the performance of the venipuncture robot. First, this study establishes a biomechanical venipuncture model, which thoroughly considers the elastic deformation, cutting, and friction of tissues and can be applied to different venipuncture conditions. Then, venipuncture simulations and in vitro phantom experiments are performed under various settings to analyze and validate the model. Finally, to evaluate the robotic humanoid venipuncture method, we apply the method to a self-developed six-degree-of-freedom venipuncture robot via rabbit ear veins with a success rate of approximately 90%. This work demonstrates that the humanoid venipuncture method based on the biomechanical model is practical and rapid in processing simple information in venipuncture robots. [ABSTRACT FROM AUTHOR]

Self‑Contained Breathing Apparatus (SCBA) is an essential piece of personal protective equipment for firefighters, providing essential respiratory support and protection. A major challenge in SCBA research is to reduce musculoskeletal disorders and enhance firefighter comfort while carrying the SCBA. In this study, a novel SCBA pack was designed to reduce SCBA‑related musculoskeletal stress. Ten volunteer firefighters were recruited to participate in the test protocol equipped with a novel SCBA (SCBANovel) and a traditional SCBA (SCBATrad) pack. Surface electromyography and pressure data were collected, and subjective ratings of discomfort using a visual analog scale. The results showed that the SCBANovel significantly reduced trapezius and erector spinae muscle activity. Shoulder and waist pressure were reduced by 19.73%‑32.83% and 18.46%‑41.55%, respectively. In addition, the SCBANovel pack reduced lower back discomfort scores by 59.1%, all compared to the SCBATrad pack. The SCBANovel pack showed a significant reduction in musculoskeletal stress and discomfort in firefighters.Practitioner SummarySCBAs are known to be critical in protecting the health of firefighters, but are often associated with firefighter discomfort and musculoskeletal disorders. We developed the SCBANovel pack and explored the effects on the upper body musculoskeletal system and comfort during walking and running compared to carrying the SCBATrad pack. The SCBANovel pack reduced muscle activity in the trapezius and erector spinae muscles and significantly reduced pressure on the shoulders and lower back.

This research paper aimed to validate two methods for measuring loads during walking with instrumented crutches: one method to estimate partial weight-bearing on the lower limbs and another to estimate shoulder joint reactions. Currently, gait laboratories, instrumented with high-end measurement systems, are used to extract kinematic and kinetic data, but such facilities are expensive and not accessible to all patients. The proposed method uses instrumented crutches to measure ground reaction forces and does not require any motion capture devices or force platforms. The load on the lower limbs is estimated by subtracting the forces measured by the crutches from the subject’s total weight. Since the model does not consider inertia contribution in dynamic conditions, the estimation improves with low walking cadence when walking with the two-point contralateral and the three-point partial weight-bearing patterns considered for the validation tests. The shoulder joint reactions are estimated using linear regression, providing accurate values for the forces but less accurate torque estimates. The crutches data are acquired and processed in real-time, allowing for immediate feedback, and the system can be used outdoors in real-world walking conditions. The validation of this method could lead to better monitoring of partial weight-bearing and shoulder joint reactions, which could improve patient outcomes and reduce complications.