RESUMEN
Recent years have witnessed breakthroughs in assistive exoskeletons; both passive and active devices have reduced metabolic costs near preferred walking speed by assisting muscle actions. Metabolic reductions at multiple speeds should thus also be attainable. Musculoskeletal simulation can potentially predict the interaction between assistive moments, muscle-tendon mechanics, and walking energetics. In this study, we simulated devices' optimal assistive moments based on minimal muscle activations during walking with prescribed kinematics and dynamics. We used a generic musculoskeletal model with tuned muscle-tendon parameters and computed metabolic rates from muscle actions. We then simulated walking across multiple speeds and with two ideal actuation modes-motor-based and spring-based-to assist ankle plantarflexion, knee extension, hip flexion, and hip abduction and compared computed metabolic rates. We found that both actuation modes considerably reduced physiological joint moments but did not always reduce metabolic rates. Compared to unassisted conditions, motor-based ankle plantarflexion and hip flexion assistance reduced metabolic rates, and this effect was more pronounced as walking speed increased. Spring-based hip flexion and abduction assistance increased metabolic rates at some walking speeds despite a moderate decrease in some muscle activations. Both modes of knee extension assistance reduced metabolic rates to a small extent, even though the actuation contributed with practically the entire net knee extension moment during stance. Motor-based hip abduction assistance reduced metabolic rates more than spring-based assistance, though this reduction was relatively small. Our study also suggests that an assistive strategy based on minimal muscle activations might result in a suboptimal reduction of metabolic rates. Future work should experimentally validate the effects of assistive moments and refine modeling assumptions accordingly. Our computational workflow is freely available online.
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Extremidad Inferior , Músculo Esquelético , Caminata , Humanos , Fenómenos Biomecánicos , Caminata/fisiología , Extremidad Inferior/fisiología , Músculo Esquelético/fisiología , Velocidad al Caminar/fisiología , Modelos Biológicos , Simulación por Computador , Tendones/fisiología , Dispositivo Exoesqueleto , Biología Computacional , Marcha/fisiologíaRESUMEN
AbstractMuscle-tendon unit (MTU) morphology and physiology are likely major determinants of locomotor performance and therefore Darwinian fitness. However, the relationships between underlying traits, performance, and fitness are complicated by phenomena such as coadaptation, multiple solutions, and trade-offs. Here, we leverage a long-running artificial selection experiment in which mice have been bred for high levels of voluntary running to explore MTU adaptation, as well as the role of coadaptation, multiple solutions, and trade-offs, in the evolution of endurance running. We compared the morphological and contractile properties of the triceps surae complex, a major locomotor MTU, in four replicate selected lines to those of the triceps surae complex in four replicate control lines. All selected lines have lighter and shorter muscles, longer tendons, and faster muscle twitch times than all control lines. Absolute and normalized maximum shortening velocities and contractile endurance vary across selected lines. Selected lines have similar or lower absolute velocities and higher endurance than control lines. However, normalized shortening velocities are both higher and lower in selected lines than in control lines. These findings potentially show an interesting coadaptation between muscle and tendon morphology and muscle physiology, highlight multiple solutions for increasing endurance running performance, demonstrate that a trade-off between muscle speed and endurance can arise in response to selection, and suggest that a novel physiology may sometimes allow this trade-off to be circumvented.
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Adaptación Fisiológica , Músculo Esquelético , Resistencia Física , Carrera , Tendones , Animales , Ratones , Carrera/fisiología , Tendones/fisiología , Resistencia Física/genética , Resistencia Física/fisiología , Músculo Esquelético/fisiología , Adaptación Fisiológica/fisiología , Evolución Biológica , Masculino , Femenino , Contracción Muscular/fisiologíaRESUMEN
In this study, we investigated the capability of the Nakagami transformation to detect changes in vastus lateralis muscle-tendon stiffness (k) during dynamic (and intense) contractions. k was evaluated in eleven healthy males using the gold-standard method (a combination of ultrasound and dynamometric measurements) during maximal and sub-maximal voluntary fixed-end contractions of the knee extensors (20, 40, 60, 80, and 100% of maximum voluntary force), while Nakagami parameters were analysed using the Nakagami transformation during the same contractions. Muscle-belly behaviour was investigated by means of B-mode ultrasound analysis, while Nakagami parameters were obtained in post-processing using radiofrequency data. k was calculated as the slope of the force-muscle-belly elongation relationship. Three contractions at each intensity were performed to calculate the intra-trial reliability and the coefficient of variation (CV) of the Nakagami parameters. At all contraction intensities, high values of intra-trial reliability (range: 0.92-0.96) and low CV (<9%) were observed. k and Nakagami parameters increased as a function of contraction intensity, and significant positive correlations were observed between these variables. These data suggest that changes in mechanical properties (e.g., stiffness) at the muscle level could be investigated by means of Nakagami parameters.
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Contracción Muscular , Ultrasonografía , Humanos , Masculino , Adulto , Contracción Muscular/fisiología , Ultrasonografía/métodos , Adulto Joven , Fenómenos Biomecánicos , Músculo Esquelético/fisiología , Músculo Esquelético/diagnóstico por imagen , Tendones/fisiología , Tendones/diagnóstico por imagen , Músculo Cuádriceps/fisiología , Músculo Cuádriceps/diagnóstico por imagenRESUMEN
Tendons enable locomotion by transmitting high tensile mechanical forces between muscle and bone via their dense extracellular matrix (ECM). The application of extrinsic mechanical stimuli via muscle contraction is necessary to regulate healthy tendon function. Specifically, applied physiological levels of mechanical loading elicit an anabolic tendon cell response, while decreased mechanical loading evokes a degradative tendon state. Although the tendon response to mechanical stimuli has implications in disease pathogenesis and clinical treatment strategies, the cell signaling mechanisms by which tendon cells sense and respond to mechanical stimuli within the native tendon ECM remain largely unknown. Therefore, we explored the role of cell-ECM adhesions in regulating tendon cell mechanotransduction by perturbing the genetic expression and signaling activity of focal adhesion kinase (FAK) through both in vitro and in vivo approaches. We determined that FAK regulates tendon cell spreading behavior and focal adhesion morphology, nuclear deformation in response to applied mechanical strain, and mechanosensitive gene expression. In addition, our data reveal that FAK signaling plays an essential role in in vivo tendon development and postnatal growth, as FAK-knockout mouse tendons demonstrated reduced tendon size, altered mechanical properties, differences in cellular composition, and reduced maturity of the deposited ECM. These data provide a foundational understanding of the role of FAK signaling as a critical regulator of in situ tendon cell mechanotransduction. Importantly, an increased understanding of tendon cell mechanotransductive mechanisms may inform clinical practice as well as lead to the discovery of diagnostic and/or therapeutic molecular targets.
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Mecanotransducción Celular , Ratones Noqueados , Tendones , Animales , Masculino , Ratones , Células Cultivadas , Matriz Extracelular/metabolismo , Quinasa 1 de Adhesión Focal/metabolismo , Quinasa 1 de Adhesión Focal/genética , Proteína-Tirosina Quinasas de Adhesión Focal/metabolismo , Proteína-Tirosina Quinasas de Adhesión Focal/genética , Adhesiones Focales/metabolismo , Mecanotransducción Celular/fisiología , Ratones Endogámicos C57BL , Transducción de Señal/fisiología , Tendones/metabolismo , Tendones/fisiología , Tendones/citología , FemeninoRESUMEN
In this paper, the innovative design of a robotic hand with soft jointed structure is carried out and a tendon-driven mechanism, a master-slave motor coordinated drive mechanism, a thumb coupling transmission mechanism and a thumb steering mechanism are proposed. These innovative designs allow for more effective actuation in each finger, enhancing the load capacity of the robotic hand while maintaining key performance indicators such as dexterity and adaptability. A mechanical model of the robotic finger was made to determine the application limitations and load capacity. The robotic hand was then prototyped for a set of experiments. The experimental results showed that the proposed theoretical model were reliable. Also, the fingertip force of the robotic finger could reach up to 10.3 N, and the load force could reach up to 72.8 N. When grasping target objects of different sizes and shapes, the robotic hand was able to perform the various power grasping and precision grasping in the Cutkosky taxonomy. Moreover, the robotic hand had good flexibility and adaptability by means of adjusting the envelope state autonomously.
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Diseño de Equipo , Fuerza de la Mano , Mano , Robótica , Robótica/instrumentación , Mano/fisiología , Humanos , Fuerza de la Mano/fisiología , Dedos/fisiología , Biomimética/métodos , Tendones/fisiología , Modelos BiológicosRESUMEN
BACKGROUND: Robot-assisted microsurgery (RAMS) is gradually becoming the preferred method for some delicate surgical procedures. However, the lack of haptic feedback reduces the safety of the surgery. Surgeons are unable to feel the grasping force between surgical instruments and the patient's tissues, which can easily lead to grasping failure or tissue damage. METHODS: This paper proposes a tendon-driven grasping force feedback mechanism, consisting of a follower hand and a leader hand, to address the lack of grasping force feedback in flexible surgical robots. Considering the friction in the tendon transmission process, a grasping force estimation model is established for the follower hand. The admittance control model is designed for force/position control of the leader hand. RESULTS: Through experimental validation, it has been confirmed that the grasping force sensing range of the follower hand is 0.5-5 N, with a sensing accuracy of 0.3 N. The leader hand is capable of providing feedback forces in the range of 0-5 N, with a static force accuracy of 0.1 N. CONCLUSIONS: The designed mechanism and control strategy can provide the grasping force feedback function. Future work will focus on improving force feedback performance. TRIAL REGISTRATION: This research has no clinical trials.
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Diseño de Equipo , Retroalimentación , Fuerza de la Mano , Procedimientos Quirúrgicos Robotizados , Humanos , Procedimientos Quirúrgicos Robotizados/métodos , Procedimientos Quirúrgicos Robotizados/instrumentación , Fuerza de la Mano/fisiología , Microcirugia/métodos , Microcirugia/instrumentación , Tendones/cirugía , Tendones/fisiología , Reproducibilidad de los ResultadosRESUMEN
Image-based deformation estimation is an important tool used in a variety of engineering problems, including crack propagation, fracture, and fatigue failure. These tools have been important in biomechanics research where measuring in vitro and in vivo tissue deformations are important for evaluating tissue health and disease progression. However, accurately measuring tissue deformation in vivo is particularly challenging due to limited image signal-to-noise ratio. Therefore, we created a novel deep-learning approach for measuring deformation from a sequence of images collected in vivo called StrainNet. Utilizing a training dataset that incorporates image artifacts, StrainNet was designed to maximize performance in challenging, in vivo settings. Artificially generated image sequences of human flexor tendons undergoing known deformations were used to compare benchmark StrainNet against two conventional image-based strain measurement techniques. StrainNet outperformed the traditional techniques by nearly 90%. High-frequency ultrasound imaging was then used to acquire images of the flexor tendons engaged during contraction. Only StrainNet was able to track tissue deformations under the in vivo test conditions. Findings revealed strong correlations between tendon deformation and applied forces, highlighting the potential for StrainNet to be a valuable tool for assessing rehabilitation strategies or disease progression. Additionally, by using real-world data to train our model, StrainNet was able to generalize and reveal important relationships between the effort exerted by the participant and tendon mechanics. Overall, StrainNet demonstrated the effectiveness of using deep learning for image-based strain analysis in vivo.
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Aprendizaje Profundo , Tendones , Ultrasonografía , Tendones/diagnóstico por imagen , Tendones/fisiología , Humanos , Ultrasonografía/métodos , Fenómenos Biomecánicos , Procesamiento de Imagen Asistido por Computador/métodosRESUMEN
The ability of a novel biorealistic hand prosthesis for grasp force control reveals improved neural compatibility between the human-prosthetic interaction. The primary purpose here was to validate a virtual training platform for amputee subjects and evaluate the respective roles of visual and tactile information in fundamental force control tasks. We developed a digital twin of tendon-driven prosthetic hand in the MuJoCo environment. Biorealistic controllers emulated a pair of antagonistic muscles controlling the index finger of the virtual hand by surface electromyographic (sEMG) signals from amputees' residual forearm muscles. Grasp force information was transmitted to amputees through evoked tactile sensation (ETS) feedback. Six forearm amputees participated in force tracking and holding tasks under different feedback conditions or using their intact hands. Test results showed that visual feedback played a predominant role than ETS feedback in force tracking and holding tasks. However, in the absence of visual feedback during the force holding task, ETS feedback significantly enhanced motor performance compared to feedforward control alone. Thus, ETS feedback still supplied reliable sensory information to facilitate amputee's ability of stable grasp force control. The effects of tactile and visual feedback on force control were subject-specific when both types of feedback were provided simultaneously. Amputees were able to integrate visual and tactile information to the biorealistic controllers and achieve a good sensorimotor performance in grasp force regulation. The virtual platform may provide a training paradigm for amputees to adapt the biorealistic hand controller and ETS feedback optimally.
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Amputados , Miembros Artificiales , Electromiografía , Retroalimentación Sensorial , Fuerza de la Mano , Mano , Diseño de Prótesis , Humanos , Retroalimentación Sensorial/fisiología , Masculino , Fuerza de la Mano/fisiología , Mano/fisiología , Adulto , Femenino , Persona de Mediana Edad , Tacto/fisiología , Músculo Esquelético/fisiología , Desempeño Psicomotor/fisiología , Antebrazo/fisiología , Fenómenos Biomecánicos , Tendones/fisiologíaRESUMEN
BACKGROUND: Tendons transmit tensile load from muscles to the skeleton. Differential loading across a tendon can occur, especially when it contains subtendons originating from distinct muscles. Tendon shear wave speed has previously been shown to reflect local tensile stress. Hence, a tool that measures spatial variations in wave speed may reflect differential loading within a tendon during human movement. RESEARCH QUESTION: Do wave speeds measured via high-framerate ultrasound-based tensiometry correspond with differential loading across a tendon? METHODS: Ultrasound-tensiometry uses an external mechanical actuator to induce waves and high-framerate plane wave ultrasound imaging (20â¯kHz) to track tissue displacements arising from wave propagation within a tendon. Local tissue displacements are temporally and spatially filtered to remove high-frequency noise and reflected waves. A Radon transform of the spatio-temporal displacement data is used to compute the shear wave speed across the tendon. We evaluated ultrasound-tensiometry's ability to measure differential loading across a tendon using in silico, ex vivo and in vivo approaches. The in silico approach used a finite element model to simulate wave propagation along two adjacent subtendons undergoing differential loading. The ex vivo experiment measured wave speed in adjacent porcine flexor subtendons subjected to differential loading. In vivo, we tracked wave speed across the Achilles tendon while a participant performed calf stretches to differentially load the subtendons, and while walking on a treadmill at 1.5â¯m/s. RESULTS: Wave speeds modulated with local tendon stress under both in silico and ex vivo conditions, with higher wave speeds observed in subtendons subjected to higher loads (6-16â¯m/s higher at 1.5× load differential). Spatial variations in in vivo Achilles tendon wave speeds were consistent with differential subtendon loading arising from distinct muscle loads (maximum range: 0-137â¯m/s, resolution: 0.1â¯mm×0.2â¯mm, precision: ±0.2â¯m/s). SIGNIFICANCE: High-framerate ultrasound-tensiometry tracks spatial variations in tendon wave speed, which may be useful to investigate local tissue loading and to delineate individual muscle contributions to movement.
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Tendón Calcáneo , Ultrasonografía , Animales , Fenómenos Biomecánicos , Tendón Calcáneo/fisiología , Tendón Calcáneo/diagnóstico por imagen , Porcinos , Humanos , Tendones/fisiología , Tendones/diagnóstico por imagen , Movimiento/fisiología , Soporte de Peso/fisiología , Análisis de Elementos Finitos , Resistencia a la Tracción/fisiologíaRESUMEN
Computational models of musculoskeletal systems are essential tools for understanding how muscles, tendons, bones, and actuation signals generate motion. In particular, the OpenSim family of models has facilitated a wide range of studies on diverse human motions, clinical studies of gait, and even non-human locomotion. However, biological structures with many joints, such as fingers, necks, tails, and spines, have been a longstanding challenge to the OpenSim modeling community, especially because these structures comprise numerous bones and are frequently actuated by extrinsic muscles that span multiple joints-often more than three-and act through a complex network of branching tendons. Existing model building software, typically optimized for limb structures, makes it difficult to build OpenSim models that accurately reflect these intricacies. Here, we introduce ArborSim, customized software that efficiently creates musculoskeletal models of highly jointed structures and can build branched muscle-tendon architectures. We used ArborSim to construct toy models of articulated structures to determine which morphological features make a structure most sensitive to branching. By comparing the joint kinematics of models constructed with branched and parallel muscle-tendon units, we found that among various parameters-the number of tendon branches, the number of joints between branches, and the ratio of muscle fiber length to muscle tendon unit length-the number of tendon branches and the number of joints between branches are most sensitive to branching modeling method. Notably, the differences between these models showed no predictable pattern with increased complexity. As the proportion of muscle increased, the kinematic differences between branched and parallel models units also increased. Our findings suggest that stress and strain interactions between distal tendon branches and proximal tendon and muscle greatly affect the overall kinematics of a musculoskeletal system. By incorporating complex muscle-tendon branching into OpenSim models using ArborSim, we can gain deeper insight into the interactions between the axial and appendicular skeleton, model the evolution and function of diverse animal tails, and understand the mechanics of more complex motions and tasks.
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Articulaciones , Músculo Esquelético , Programas Informáticos , Tendones , Tendones/fisiología , Tendones/anatomía & histología , Humanos , Fenómenos Biomecánicos , Articulaciones/fisiología , Articulaciones/anatomía & histología , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Modelos Biológicos , Biología Computacional , Simulación por Computador , AnimalesRESUMEN
ABSTRACT: Stone, MH, Hornsby, G, Mizuguchi, S, Sato, K, Gahreman, D, Duca, M, Carroll, K, Ramsey, MW, Stone, ME, and Haff, GG. The use of free weight squats in sports: a narrative review-squatting movements, adaptation, and sports performance: physiological. J Strength Cond Res 38(8): 1494-1508, 2024-The squat and its variants can provide numerous benefits including positively affecting sports performance and injury prevention, injury severity reduction, and rehabilitation. The positive benefits of squat are likely the result of training-induced neural alterations and mechanical and morphological adaptations in tendons, skeletal muscles, and bones, resulting in increased tissue stiffness and cross-sectional area (CSA). Although direct evidence is lacking, structural adaptations can also be expected to occur in ligaments. These adaptations are thought to beneficially increase force transmission and mechanical resistance (e.g., resistance to mechanical strain) and reduce the likelihood and severity of injuries. Adaptations such as these, also likely play an important role in rehabilitation, particularly for injuries that require restricted use or immobilization of body parts and thus lead to a consequential reduction in the CSA and alterations in the mechanical properties of tendons, skeletal muscles, and ligaments. Both volume and particularly intensity (e.g., levels of loading used) of training seem to be important for the mechanical and morphological adaptations for at least skeletal muscles, tendons, and bones. Therefore, the training intensity and volume used for the squat and its variations should progressively become greater while adhering to the concept of periodization and recognized training principles.
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Adaptación Fisiológica , Rendimiento Atlético , Músculo Esquelético , Humanos , Rendimiento Atlético/fisiología , Adaptación Fisiológica/fisiología , Músculo Esquelético/fisiología , Entrenamiento de Fuerza/métodos , Movimiento/fisiología , Tendones/fisiología , Fenómenos BiomecánicosRESUMEN
The complexity of wrist anatomy and mechanics makes it challenging to develop standardized measurements and establish a normative reference database of wrist biomechanics despite being studied extensively. Moreover, heterogeneity factors in both demographic characteristics (e.g. gender) and physiological properties (e.g. ligament laxity) could lead to differences in biomechanical behaviour even within healthy groups. We investigated the kinematic behaviour of the carpal bones by creating a virtual web-like network between the bones using electromagnetic (EM) sensors. Our objective was to quantify the changes in the carpal bones' biomechanical relative motions and orientations during active wrist motion in the form of orb-web architecture. Models from five cadaveric specimens at different wrist positions: (1) Neutral to 30° Extension, (2) Neutral to 50° Flexion, (3) Neutral to 10° Radial Deviation, (4) Neutral to 20° Ulnar Deviation, and (5) Dart-Throw Motion - Extension (30° Extension/10° RD) to Dart-Throw Motion Flexion (50° Flexion/20° UD), in both neutral and pronated forearm have been analyzed. Quantification analyses were done by measuring the changes in the network thread length, as well as determining the correlation between the threads at different wrist positions. We observed similarities in the kinematic web-network patterns across all specimens, and the interactions between the network threads were aligned to the carpal bones' kinematic behaviour. Furthermore, analyzing the relative changes in the wrist web network has the potential to address the heterogeneity challenges and further facilitate the development of a 3D wrist biomechanics quantitative tool.
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Tendones , Articulación de la Muñeca , Humanos , Articulación de la Muñeca/fisiología , Fenómenos Biomecánicos , Tendones/fisiología , Huesos del Carpo/fisiología , Masculino , Modelos Biológicos , Femenino , Rango del Movimiento Articular/fisiología , Persona de Mediana Edad , AncianoRESUMEN
The aim of our study is to evaluate preserving gracilis tendon in anterior cruciate ligament reconstruction (ACLR) surgery and its effect to the flexion of the knee joint and tibial internal rotation strength and the stability of the knee. Patients who underwent primary single-bundle arthroscopic ACLR using all-inside technique and using hamstring tendon autograft were evaluated retrospectively. Patients were divided into two groups as gracilis preserved (St) and gracilis harvested (StG) groups. The International Knee Documentation Committee (IKDC) score, Lysholm, Knee Injury and Osteoarthritis Outcome Score-Knee-related quality of life (KOOS-QOL) score, ACL-Return to Sport after Injury scale score were used to evaluate as postoperative functional scores at last follow-up. Anterior tibial translation was evaluated using the KT-1000 device. Knee joint flexion, extension, and internal rotation strength were evaluated using isokinetic dynamometer. Dynamic balance performances were measured using the Biodex Balance System. There were 24 patients in the St group and 23 patients in the StG group. Demographic data and clinical results showed no significant difference. Anteroposterior movement of the tibia was found to be significantly higher in the StG group than in the St group in measurements at 89 and 134 N, respectively (p = 0.01 and <0.001). No statistically significant difference was found between both standard and deep flexor and extensor and internal rotator strength. No statistically significant difference was found in the amount of total, anteroposterior, and mediolateral balance deficit between the two groups. Additional gracilis harvesting does not have a negative effect on both standard and deep knee flexion, and tibial internal rotation strength compared with the St group. Although semitendinosus and StG group showed significantly more anterior tibial translation, there was no significant difference in clinical and dynamic stability measurements.
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Reconstrucción del Ligamento Cruzado Anterior , Artroscopía , Inestabilidad de la Articulación , Articulación de la Rodilla , Fuerza Muscular , Humanos , Fuerza Muscular/fisiología , Adulto , Masculino , Femenino , Estudios Retrospectivos , Inestabilidad de la Articulación/prevención & control , Inestabilidad de la Articulación/cirugía , Inestabilidad de la Articulación/fisiopatología , Articulación de la Rodilla/cirugía , Articulación de la Rodilla/fisiopatología , Articulación de la Rodilla/fisiología , Adulto Joven , Músculo Grácil/trasplante , Rango del Movimiento Articular , Lesiones del Ligamento Cruzado Anterior/cirugía , Lesiones del Ligamento Cruzado Anterior/fisiopatología , Tendones/cirugía , Tendones/fisiología , Tendones Isquiotibiales/trasplanteRESUMEN
OBJECTIVE: To systematically review the effects of low-load blood flow restriction training (LL-BFR) on healthy adult tendons. DESIGN: A systematic review with meta-analysis. LITERATURE SEARCH: Six electronic databases were searched by two researchers. STUDY SELECTION CRITERIA: Clinical trials comparing the effects of LL-BFR to high-load resistance training (HL-RT) or low-load resistance training (LL-RT) in healthy adult tendons. DATA SYNTHESIS: Two reviewers selected the eligible clinical trials, and one reviewer exported the data. Two reviewers evaluated the study quality and risk of bias using the PEDro scale and the ROB2 scale. We performed meta-analysis where appropriate using a random-effects model. We rated the quality of evidence using GRADE. RESULTS: Six studies were eligible. We analyzed tendon cross-sectional area (CSA) and tendon stiffness as the outcomes. Across all comparisons, there was low-to moderate-quality evidence of a difference between LL-BFR and LL-RT immediately after exercise. There was high-quality evidence of no difference between LL-BFR and HL-RT in the long term. CONCLUSION: The effects of LL-BFR on the tendons depends on the time and dose of the intervention. LL-BFR could be useful to increase the CSA of the tendons in a similar or superior way to HL-RT after 8 weeks of intervention.
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Entrenamiento de Fuerza , Tendones , Humanos , Entrenamiento de Fuerza/métodos , Tendones/fisiología , Tendones/irrigación sanguínea , Flujo Sanguíneo Regional/fisiología , Terapia de Restricción del Flujo Sanguíneo/métodos , AdultoRESUMEN
The workflow to simulate motion with recorded data usually starts with selecting a generic musculoskeletal model and scaling it to represent subject-specific characteristics. Simulating muscle dynamics with muscle-tendon parameters computed from existing scaling methods in literature, however, yields some inconsistencies compared to measurable outcomes. For instance, simulating fiber lengths and muscle excitations during walking with linearly scaled parameters does not resemble established patterns in the literature. This study presents a tool that leverages reported in vivo experimental observations to tune muscle-tendon parameters and evaluates their influence in estimating muscle excitations and metabolic costs during walking. From a scaled generic musculoskeletal model, we tuned optimal fiber length, tendon slack length, and tendon stiffness to match reported fiber lengths from ultrasound imaging and muscle passive force-length relationships to match reported in vivo joint moment-angle relationships. With tuned parameters, muscle contracted more isometrically, and soleus's operating range was better estimated than with linearly scaled parameters. Also, with tuned parameters, on/off timing of nearly all muscles' excitations in the model agreed with reported electromyographic signals, and metabolic rate trajectories varied significantly throughout the gait cycle compared to linearly scaled parameters. Our tool, freely available online, can customize muscle-tendon parameters easily and be adapted to incorporate more experimental data.
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Fibras Musculares Esqueléticas , Tendones , Tendones/fisiología , Tendones/diagnóstico por imagen , Humanos , Fibras Musculares Esqueléticas/fisiología , Músculo Esquelético/fisiología , Fenómenos Biomecánicos , Caminata/fisiología , Marcha/fisiología , Electromiografía , Modelos Biológicos , Masculino , Simulación por ComputadorRESUMEN
BACKGROUND: Methodological heterogeneity hinders data comparisons across isolated studies of tendon and ligament properties, limiting clinical understanding and affecting the development and evaluation of replacement materials. PURPOSE: To create an open-access data set on the morphological, biomechanical, and biochemical properties of clinically important tendons and ligaments of the lower limb, using consistent methodologies, to enable direct tendon/ligament comparisons. STUDY DESIGN: Descriptive laboratory study. METHODS: Nineteen distinct lower limb tendons and ligaments were retrieved from 8 fresh-frozen human cadavers (5 male, 3 female; aged 49-65 years) including Achilles, tibialis posterior, tibialis anterior, fibularis (peroneus) longus, fibularis (peroneus) brevis, flexor hallucis longus, extensor hallucis longus, plantaris, flexor digitorum longus, quadriceps, patellar, semitendinosus, and gracilis tendons; anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments; and 10 mm-wide grafts from the contralateral quadriceps and patellar tendons. Outcomes included morphology (tissue length, ultrasound-quantified cross-sectional area [CSAUS], and major and minor axes), biomechanics (failure load, ultimate tensile strength [UTS], failure strain, and elastic modulus), and biochemistry (sulfated glycosaminoglycan [sGAG] and hydroxyproline contents). Tissue differences were analyzed using mixed-model regression. RESULTS: There was a range of similarities and differences between tendons and ligaments across outcomes. A key finding relating to potential graft tissue suitability was the comparable failure loads, UTS, CSAUS, sGAG, and hydroxyproline present between hamstring tendons (a standard graft source) and 5 tendons not typically used for grafting: fibularis (peroneus) longus and brevis, flexor and extensor hallucis longus, and flexor digitorum longus tendons. CONCLUSION: This study of lower limb tendons and ligaments has enabled direct comparison of morphological, biomechanical, and biochemical human tissue properties-key factors in the selection of suitable graft tissues. This analysis has identified 6 potential new donor tissues with properties comparable to currently used grafts. CLINICAL RELEVANCE: This extensive data set reduces the need to utilize data from incompatible sources, which may aid surgical decisions (eg, evidence to expand the range of tendons considered suitable for use as grafts) and may provide congruent design inputs for new biomaterials and computational models. The complete data set has been provided to facilitate further investigations, with the capacity to expand the resource to include additional outcomes and tissues.
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Cadáver , Ligamentos , Extremidad Inferior , Tendones , Humanos , Masculino , Femenino , Persona de Mediana Edad , Tendones/anatomía & histología , Tendones/fisiología , Anciano , Fenómenos Biomecánicos , Ligamentos/anatomía & histología , Ligamentos/fisiología , Extremidad Inferior/anatomía & histología , Extremidad Inferior/fisiología , Resistencia a la Tracción/fisiologíaRESUMEN
The present work reports on the multiaxial region and orientation-dependent mechanical properties of two porcine wrap-around tendons under tensile, compressive and combined loads based on an extensive study with n=175 samples. The results provide a detailed dataset of the anisotropic tensile and compressive longitudinal properties and document a pronounced tension-compression asymmetry. Motivated by the physiological loading conditions of these tendons, which include transversal compression at bony abutments in addition to longitudinal tension, we systematically investigated the change in axial tension when the tendon is compressed transversally along one or both perpendicular directions. The results reveal that the transversal compression can increase axial tension (proximal-distal direction) in both cases to orders of 30%, yet by a larger amount in the first case (transversal compression in anterior-posterior direction), which seems to be more relevant for wrap-around tendons in-vivo. These quantitative measurements are in line with earlier findings on auxetic properties of tendon tissue, but show for the first time the influence of this property on the stress response of the tendon, and may thus reveal an important functional principle within these essential elements of force transmission in the body. STATEMENT OF SIGNIFICANCE: The work reports for the first time on multiaxial region and orientation-dependent mechanical properties of wrap-around tendons under various loads. The results indicate that differences in the mechanical properties exist between zones that are predominantly in a uniaxial tensile state and those that experience complex load states. The observed counterintuitive increase of the axial tension upon lateral compression points at auxetic properties of the tendon tissue which may be pivotal for the function of the tendon as an element of the musculoskeletal system. It suggests that the tendon's performance in transmitting forces is not diminished but enhanced when the action line is deflected by a bony pulley around which the tendon wraps, representing an important functional principle of tendon tissue.
Asunto(s)
Fuerza Compresiva , Tendones , Resistencia a la Tracción , Animales , Anisotropía , Tendones/fisiología , Porcinos , Estrés Mecánico , Soporte de Peso/fisiología , Fenómenos BiomecánicosRESUMEN
Lumbrical muscles originate on the flexor digitorum profundus (FDP) tendons and, during fist making, they move in the same direction when FDP muscle produces maximal proximal tendon gliding. Injuries of the bipennate lumbricals have been described when a shear force acts between the origins on adjacent tendons of the FDP, as they glide in opposite directions in asymmetric hand postures. Other structures of the deep flexors complex can be affected during this injury mechanism, due to the so-called quadriga effect, which can commonly occur during sport climbing practise. Biomechanical studies are needed to better understand the pathomechanism. A cadaveric study was designed to analyse the effects of load during the fourth lumbrical muscle injury mechanism. The amount of FDP tendon gliding and metacarpophalangeal (MCP) joint flexion of the 5th finger were calculated. Ten fresh-frozen cadaveric specimens (ten non-paired forearms and hands) were used. The specimens were placed on a custom-made loading apparatus. The FDP of the 5th finger was loaded, inducing isolated flexion of the 5th finger, until rupture. The rupture occurred in all specimens, under a load of 11 kg (SD 4.94), at 9.23 mm of proximal tendon gliding (SD 3.55) and at 21.4° (SD 28.91) of MCP joint flexion. Lumbrical muscle detachment from the 4th FDP was observed, from distal to proximal, and changes in FDP tendons at the distal forearm level too. The quadriga effect can lead to injury of the bipennate lumbrical muscles and the deep flexors complex in the hand and forearm.
Asunto(s)
Cadáver , Músculo Esquelético , Tendones , Humanos , Músculo Esquelético/fisiopatología , Músculo Esquelético/fisiología , Tendones/fisiopatología , Tendones/fisiología , Fenómenos Biomecánicos , Masculino , Montañismo/fisiología , Persona de Mediana Edad , Anciano , Traumatismos de los Tendones/fisiopatología , Femenino , Antebrazo/fisiopatología , Antebrazo/fisiología , Rotura/fisiopatología , Articulación Metacarpofalángica/fisiopatología , Articulación Metacarpofalángica/lesiones , Modelos BiológicosRESUMEN
BACKGROUND: Tendon stem/progenitor cell (TSPC) senescence contributes to tendon degeneration and impaired tendon repair, resulting in age-related tendon disorders. Ferroptosis, a unique iron-dependent form of programmed cell death, might participate in the process of senescence. However, whether ferroptosis plays a role in TSPC senescence and tendon regeneration remains unclear. Recent studies reported that Platelet-derived exosomes (PL-Exos) might provide significant advantages in musculoskeletal regeneration and inflammation regulation. The effects and mechanism of PL-Exos on TSPC senescence and tendon regeneration are worthy of further study. METHODS: Herein, we examined the role of ferroptosis in the pathogenesis of TSPC senescence. PL-Exos were isolated and determined by TEM, particle size analysis, western blot and mass spectrometry identification. We investigated the function and underlying mechanisms of PL-Exos in TSPC senescence and ferroptosis via western blot, real-time quantitative polymerase chain reaction, and immunofluorescence analysis in vitro. Tendon regeneration was evaluated by HE staining, Safranin-O staining, and biomechanical tests in a rotator cuff tear model in rats. RESULTS: We discovered that ferroptosis was involved in senescent TSPCs. Furthermore, PL-Exos mitigated the aging phenotypes and ferroptosis of TSPCs induced by t-BHP and preserved their proliferation and tenogenic capacity. The in vivo animal results indicated that PL-Exos improved tendon-bone healing properties and mechanical strength. Mechanistically, PL-Exos activated AMPK phosphorylation and the downstream nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway, leading to the suppression of lipid peroxidation. AMPK inhibition or GPX4 inhibition blocked the protective effect of PL-Exos against t-BHP-induced ferroptosis and senescence. CONCLUSION: In conclusion, ferroptosis might play a crucial role in TSPC aging. AMPK/Nrf2/GPX4 activation by PL-Exos was found to inhibit ferroptosis, consequently leading to the suppression of senescence in TSPCs. Our results provided new theoretical evidence for the potential application of PL-Exos to restrain tendon degeneration and promote tendon regeneration.