{ "types" : { "Bookmark" : { "pluralLabel" : "Bookmarks" }, "Publication" : { "pluralLabel" : "Publications" }, "GoldStandardPublication" : { "pluralLabel" : "GoldStandardPublications" }, "GoldStandardBookmark" : { "pluralLabel" : "GoldStandardBookmarks" }, "Tag" : { "pluralLabel" : "Tags" }, "User" : { "pluralLabel" : "Users" }, "Group" : { "pluralLabel" : "Groups" }, "Sphere" : { "pluralLabel" : "Spheres" } }, "properties" : { "count" : { "valueType" : "number" }, "date" : { "valueType" : "date" }, "changeDate" : { "valueType" : "date" }, "url" : { "valueType" : "url" }, "id" : { "valueType" : "url" }, "tags" : { "valueType" : "item" }, "user" : { "valueType" : "item" } }, "items" : [ { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2cbec912855d58b7684527239ad3d1666/inspo5", "tags" : [ "joint","Dynamics","Tibia-metatarsus","Drag","Aspect","Semi-hydraulic","Hemolymph","Muscle","leg","ratio" ], "intraHash" : "cbec912855d58b7684527239ad3d1666", "interHash" : "c85ede589b7a13caabc8c25fa8520592", "label" : "Semi-hydraulic actuation in spider legs: The transport of the hemolymph does not hamper muscle driven leg joint flexion", "user" : "inspo5", "description" : "", "date" : "2025-12-18 11:27:05", "changeDate" : "2025-12-18 11:27:05", "count" : 2, "pub-type": "article", "journal": "Journal of Theoretical Biology","publisher":"Elsevier BV", "year": "2025", "url": "http://dx.doi.org/10.1016/j.jtbi.2025.112350", "author": [ "Reinhard Blickhan","Tobias Siebert","Tom Weihmann" ], "authors": [ {"first" : "Reinhard", "last" : "Blickhan"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Tom", "last" : "Weihmann"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "pages": "112350","abstract": "Hemolymph channels (lacunae) in the legs of spiders are part of their open circulatory system. They are defined as hemolymph-filled spaces between tissues within the exoskeletal tubes of the legs which are otherwise largely filled with muscles. In two of the major leg joints, the leg segments are connected via hinge joints with axes that are located at their dorsal rims.\r\nThe lacunae are used to channel hemolymph, which acts as a hydraulic fluid, to the extensor-less joints during the extension of the legs. However, due to competing optimization criteria of muscle-driven flexion and drainage of the hemolymph, fluid drag in the lacunae may hinder movement and force generation during flexion. Numerical modelling of dynamic flexions of the tibia-metatarsus joint, considering anatomical and physiological properties identified in the hunting spider Cupiennius salei, was used to investigate the trade-off between muscular force and hemolymph-drainage. The results showed that the diameters of the hemolymph channels exhibit a broad optimum for quick flexion. Within a wide range of channel diameters flexion times are hardly affected. Muscle properties, especially the time of muscle activation, strongly dampen the effect of the reduced muscle cross-section available. With small loads of 0.1\u202Fg, similar to the spiders\u2019 common prey size, the radius of the observed effective lacunae seems to enable the fastest flexions. A change in the aspect ratio of the tibia while maintaining the proportionality of its radius and the radius of the effective hemolymph channels leads to an extension of the flexion time.", "issn" : "0022-5193", "doi" : "10.1016/j.jtbi.2025.112350", "bibtexKey": "Blickhan_2025" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/25f223bfc85d55493de07f7c8c5d9718a/inspo5", "tags" : [ "disorders","apogee","activity","electromyography","lower","muscle","back","exoskeleton","active","musculoskeletal","velocity","movement" ], "intraHash" : "5f223bfc85d55493de07f7c8c5d9718a", "interHash" : "d43970df13496122338acd5777620812", "label" : "Biomechanical analysis of different lifting speeds when using an active exoskeleton", "user" : "inspo5", "description" : "", "date" : "2025-11-14 11:42:57", "changeDate" : "2025-11-14 11:42:57", "count" : 2, "pub-type": "article", "journal": "Frontiers Bioeng. Biotechnol. Sec.Biomechanics", "year": "2025", "url": "https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2025.1685634/full", "author": [ "Dominik Mayer","Tobias Siebert","Jens Hasenmaier","Norman Stutzig" ], "authors": [ {"first" : "Dominik", "last" : "Mayer"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Jens", "last" : "Hasenmaier"}, {"first" : "Norman", "last" : "Stutzig"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "13","abstract": "Introduction: Musculoskeletal disorders (MSDs), especially lower back pain, are common consequences of repetitive and long-term mechanical stress. Exoskeletons offer a promising approach to reduce this stress by supporting the wearer during physical labour. This study investigated the effect of an active exoskeleton (Apogee) on muscle activation and joint kinematics during load lifting at different lifting speeds and exoskeleton support levels.\r\n\r\nMethods: Sixteen healthy young adults (8 male, 8 female) lifted a 15 kg box at two lifting speeds (9 and 12 lifting cycles/min) and four support levels: 1) without exoskeleton, 2) exoskeleton in passive mode, 3) 50% support and 20% counterforce, 4) 100% support and 60% counterforce. Muscle activity was measured in the M. erector spinae (MES), M. biceps femoris (MBF) and M. vastus medialis (MVM) using EMG. Furthermore, joint range of motion (ROM) in the ankle, knee and hip were analysed using 3D motion capture.\r\n\r\nResults: Faster lifting significantly (p < 0.05) increased MBF (by 4.0% ± 1.5% maximum voluntary contraction, MVC) and MVM (1.6% ± 0.7% MVC) activity, while MES remained unaffected. The highest support level led to a significant decrease in MES and MBF activity by about 22.3% MVC and 10.6% MVC, respectively, as well as a small increase in hip joint ROM by 6° compared to lifting without exoskeleton support. There was no interaction between the level of support and lifting speed.\r\n\r\nDiscussion: The decrease in MES activity of 22.3% MVC with full support suggests a potent reduction in spinal load. MBF activity increased less with higher speeds when support was applied. The MVM showed low and stable activity across all conditions. These findings suggest that the active exoskeleton Apogee provides support regardless of lifting speed and may help prevent MSDs in occupational settings. Users can adjust support levels based on task requirements and personal comfort.", "language" : "English", "doi" : "10.3389/fbioe.2025.1685634", "bibtexKey": "mayer2025biomechanical" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/24bec4570c7f790b34e93b3dcb55fdece/inspo5", "tags" : [ "muscle-tendon","locomotion","muscle","robotics" ], "intraHash" : "4bec4570c7f790b34e93b3dcb55fdece", "interHash" : "f68a586961d502b30664b5b508a67bb0", "label" : "Muscle\u2013tendon mechanics resolve the trade-off between energy-efficient and robust locomotion", "user" : "inspo5", "description" : "", "date" : "2025-11-05 14:58:13", "changeDate" : "2025-11-05 14:58:13", "count" : 1, "pub-type": "article", "journal": "Biology Letters","publisher":"The Royal Society", "year": "2025", "url": "http://dx.doi.org/10.1098/rsbl.2025.0200", "author": [ "Matthew Araz","Tobias Siebert","Alexander Badri-Spröwitz","Syn Schmitt","Daniel F. B. Haeufle" ], "authors": [ {"first" : "Matthew", "last" : "Araz"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Alexander", "last" : "Badri-Spröwitz"}, {"first" : "Syn", "last" : "Schmitt"}, {"first" : "Daniel F. B.", "last" : "Haeufle"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "21","number": "11","abstract": "Animals utilize elastic tendons in their limbs to store and release energy, reducing muscle effort and overall energy expenditure. At the same time, they navigate rough terrain dynamically without falling, despite significant neural delays. This ability allows them to achieve both robust and energy-efficient locomotion simultaneously\u2014two properties often considered trade-offs in robotics. Through computational simulations, this study demonstrates how muscle\u2013tendon mechanics can facilitate both energy-efficient and robust locomotion during perturbed vertical hopping across different muscle\u2013tendon length configurations. Integrating muscle\u2013tendon-like viscoelastic materials into legged robots may offer a solution to the previously perceived trade-off.", "language" : "English", "issn" : "1744-957X", "preprinturl" : "https://royalsocietypublishing.org/doi/10.1098/rsbl.2025.0200", "doi" : "10.1098/rsbl.2025.0200", "bibtexKey": "Araz_2025" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2e278e56571667204e41214ae82b33ff8/inspo5", "tags" : [ "microstructure","Soleus","experiments","Plantaris","tissue","characteristics","cuniculus","muscles","Morphology","Mechanical","muscle","Oryctolagus","Muscle","dependent","Gastrocnemius","Age" ], "intraHash" : "e278e56571667204e41214ae82b33ff8", "interHash" : "69776921c88e79d221d10d5313558951", "label" : "Age-dependent properties of the rabbit calf musculature \u2014 Relationship between mechanic and microstructure", "user" : "inspo5", "description" : "", "date" : "2025-05-15 15:36:41", "changeDate" : "2025-05-15 15:36:41", "count" : 2, "pub-type": "article", "journal": "Journal of the Mechanical Behavior of Biomedical Materials","publisher":"Elsevier BV", "year": "2025", "url": "http://dx.doi.org/10.1016/j.jmbbm.2025.107008", "author": [ "Markus Böl","Kay Leichsenring","Steven Kutschke","Fabian Walter","Tobias Siebert" ], "authors": [ {"first" : "Markus", "last" : "Böl"}, {"first" : "Kay", "last" : "Leichsenring"}, {"first" : "Steven", "last" : "Kutschke"}, {"first" : "Fabian", "last" : "Walter"}, {"first" : "Tobias", "last" : "Siebert"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "168","pages": "107008","abstract": "In order to meet the requirements of body weight and height and the associated changing tasks and movement patterns during the growth of living bodies, significant changes in the skeletal musculature occur during this phase. In this study, the age-dependent (between 21 and 100 days) mechanical and microstructural tissue behaviour of the calf musculature, consisting of soleus muscles (SOL), gastrocnemius muscles (GAS) and plantaris muscles (PLA), was examined. To this end, cubic muscle tissue samples were examined using axial and semi-confined compression experiments. In addition, the essential muscle tissue components (muscle fibres, extracellular matrix, remaining components) were analysed. In a final step, these results were linked to morphological properties of the animals and muscles (animal mass, muscle mass, tibia length). Interestingly, the mechanical properties of the individual muscle types hardly differ from each other during growth, while both the morphological and microstructural properties change significantly. Thus, a clear increase of all morphological parameters (animal mass by 850%, muscle mass by 1000% (SOL), 1183% (GAS) and 1050% (PLA), tibia length by 235%) can be seen. In comparison, the microstructural parameters show a less consistent trend. The proportion of muscle fibres in the tissue cross-section increases by about 138% in the SOL, whereas the fibre proportion in both the GAS and PLA increases by only 109%. Consequently, the ECM proportion in the tissue cross-section decreases by 48%, 58% and 52% for SOL, GAS and PLA. Overall, the data obtained her e provides a deeper understanding of muscle growth and, in particular, of different muscle types that have different functions inside the calf. On the other hand, these data represent a good and comprehensive basis for later model developments.", "language" : "English", "issn" : "1751-6161", "doi" : "10.1016/j.jmbbm.2025.107008", "bibtexKey": "B_l_2025" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2d4c6f9a31ee0320fc3be6307a85d6c4e/inspo5", "tags" : [ "Titin","Simtech","muscle","Contractile","Stretch","physiology","Muscle","behaviour","Sarcomere","Skeletal" ], "intraHash" : "d4c6f9a31ee0320fc3be6307a85d6c4e", "interHash" : "c1587910394340ebda12596b663f7b66", "label" : "Eccentric muscle contractions : from single muscle fibre to whole muscle mechanics", "user" : "inspo5", "description" : "", "date" : "2025-02-03 10:48:28", "changeDate" : "2025-02-03 11:10:28", "count" : 5, "pub-type": "article", "journal": "Pflügers Archiv","publisher":"Springer", "year": "2023", "url": "", "author": [ "André Tomalka" ], "authors": [ {"first" : "André", "last" : "Tomalka"} ], "volume": "475","pages": "421-435","abstract": "Eccentric muscle loading encompasses several unique features compared to other types of contractions. These features include increased force, work, and performance at decreased oxygen consumption, reduced metabolic cost, improved energy efficiency, as well as decreased muscle activity. This review summarises explanatory approaches to long-standing questions in terms of muscular contraction dynamics and molecular and cellular mechanisms underlying eccentric muscle loading. Moreover, this article intends to underscore the functional link between sarcomeric components, emphasising the fundamental role of titin in skeletal muscle. The giant filament titin reveals versatile functions ranging from sarcomere organisation and maintenance, providing passive tension and elasticity, and operates as a mechanosensory and signalling platform. Structurally, titin consists of a viscoelastic spring segment that allows activation-dependent coupling to actin. This titin-actin interaction can explain linear force increases in active lengthening experiments in biological systems. A three-filament model of skeletal muscle force production (mediated by titin) is supposed to overcome significant deviations between experimental observations and predictions by the classic sliding-filament and cross-bridge theories. Taken together, this review intends to contribute to a more detailed understanding of overall muscle behaviour and force generation\u2014from a microscopic sarcomere level to a macroscopic multi-joint muscle level\u2014impacting muscle modelling, the understanding of muscle function, and disease.", "issn" : "1432-2013", "language" : "eng", "doi" : "10.1007/s00424-023-02794-z", "bibtexKey": "tomalka2023eccentric" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/26ae557bda4245c64d9be9293e67104dd/inspo5", "tags" : [ "Photogrammetric","pennation","geometry","length","Muscle","compartments","Fascicle","reconstruction","curvature" ], "intraHash" : "6ae557bda4245c64d9be9293e67104dd", "interHash" : "665b863a52d2c8a3419188684061b167", "label" : "Influence of muscle packing on the three-dimensional architecture of rabbit M. plantaris", "user" : "inspo5", "description" : "", "date" : "2024-12-19 16:44:48", "changeDate" : "2024-12-19 16:44:48", "count" : 3, "pub-type": "article", "journal": "Journal of the Mechanical Behavior of Biomedical Materials", "year": "2024", "url": "https://www.sciencedirect.com/science/article/pii/S1751616124003941?via%3Dihub", "author": [ "Mischa Borsdorf","Stefan Papenkort","Markus Böl","Tobias Siebert" ], "authors": [ {"first" : "Mischa", "last" : "Borsdorf"}, {"first" : "Stefan", "last" : "Papenkort"}, {"first" : "Markus", "last" : "Böl"}, {"first" : "Tobias", "last" : "Siebert"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "160","abstract": "In their physiological condition, muscles are surrounded by connective tissue, other muscles and bone. These tissues exert transverse forces that change the three-dimensional shape of the muscle compared to its isolated condition, in which all surrounding tissues are removed. A change in shape affects the architecture of a muscle and therefore its mechanical properties. The rabbit M. plantaris is a multi-pennate calf muscle consisting of two compartments. A smaller, bi-pennate inner muscle compartment is embedded in a larger, uni-pennate outer compartment (Böl et al., 2015). As part of the calf, the plantaris is tightly packed between other muscles. It is unclear how packing affects the shape and architecture of the plantaris. Therefore, we examined the isolated and packed plantaris of the contralateral legs of three rabbits to determine the influence of the surrounding muscles on its shape and architectural properties using photogrammetric reconstruction and manual digitization, respectively. In the packed condition, the plantaris showed a 27% increase in fascicle pennation and a 54% increase in fascicle curvature compared to the isolated condition. Fascicle length was not affected by muscle packing. The change in muscle architecture occurred mainly in the outer compartment of the plantaris. Furthermore, the isolated plantaris showed a more circular shape and a reduced width of its muscle belly. It can be concluded that the packed plantaris is flattened by the forces exerted by the surrounding muscles, causing a complex architectural change. The data provided improve our understanding of muscle packages in general and can be used to develop and validate realistic three-dimensional muscle models.", "language" : "English", "doi" : "10.1016/j.jmbbm.2024.106762", "bibtexKey": "siebert2024influence" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2dd555a4fd35faa41b3f9a475802f1084/inspo5", "tags" : [ "joint","moment","muscle-tendon","dynamics","gearing","locomotion","muscle","sound","ultra","force","enhancement" ], "intraHash" : "dd555a4fd35faa41b3f9a475802f1084", "interHash" : "16909b6df8a0d1c17a291e8e0cb7eaf7", "label" : "Decoupling of muscle-tendon unit and fascicle velocity contributes to the in vivo stretch-shortening cycle effect in the male human triceps surae muscle", "user" : "inspo5", "description" : "", "date" : "2024-12-19 16:12:00", "changeDate" : "2024-12-19 16:12:00", "count" : 2, "pub-type": "article", "journal": "The Physiological Society", "year": "2024", "url": "https://physoc.onlinelibrary.wiley.com/doi/10.14814/phy2.70131", "author": [ "Denis Holzer","Daniel Hahn","Ansgar Schwirtz","Tobias Siebert","Wolfgang Seiberl" ], "authors": [ {"first" : "Denis", "last" : "Holzer"}, {"first" : "Daniel", "last" : "Hahn"}, {"first" : "Ansgar", "last" : "Schwirtz"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Wolfgang", "last" : "Seiberl"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "12","number": "23","pages": "e70131","abstract": "During the shortening of stretch-shortening cycles (SSCs), muscle force output is enhanced compared with pure shortening (SHO), referred to as the SSC-effect. In general, muscle-tendon unit (MTU), muscle belly, muscle fascicle, and tendon length changes can be decoupled during contraction, which affects force generation and elastic recoil. We researched whether MTU decoupling contributes to the SSC-effect. Participants performed electrically stimulated submaximal fixed-end, SSC, and SHO plantar-flexions on a dynamometer at two velocities (40, 120°/s) and two ranges of motion (15, 25°). Fascicle and tendon length changes of the gastrocnemius medialis, and ankle joint kinematics were assessed by ultrasound and motion capture, respectively. During SSC shortening, ankle joint torque and work, MTU force and work, and fascicle force were increased by 12%\u201322% compared with SHO, confirming a SSC-effect. Further, fascicle length change and velocity during SSCs were significantly reduced compared with SHO condition, and SSC fascicle work was decreased by ~35%. Our results indicate that MTU decoupling leads to a reduction in fascicle shortening amplitude and velocity, thereby increasing the muscle's force capacity while reducing its work output during SSC shortening. MTU decoupling therefore contributes to the SSC-effect and underlines the limited transferability of joint work measurements to estimated muscle work.", "language" : "English", "doi" : "10.14814/phy2.70131", "bibtexKey": "holzer2024decoupling" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2112b47e516f3b08e53d295d89027127a/inspo5", "tags" : [ "gearing","Muscle","AGR","Ultrasound","architecture" ], "intraHash" : "112b47e516f3b08e53d295d89027127a", "interHash" : "7118ef30d9e0d0109338f9b611d56769", "label" : "Impact of contraction intensity and ankle joint angle on calf muscle fascicle length and pennation angle during isometric and dynamic contractions", "user" : "inspo5", "description" : "", "date" : "2024-10-23 16:21:18", "changeDate" : "2024-10-23 16:21:18", "count" : 6, "pub-type": "article", "journal": "Scientific Reports", "year": "2024", "url": "https://doi.org/10.1038/s41598-024-75795-2", "author": [ "Corinna Coenning","Volker Rieg","Tobias Siebert","Veit Wank" ], "authors": [ {"first" : "Corinna", "last" : "Coenning"}, {"first" : "Volker", "last" : "Rieg"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Veit", "last" : "Wank"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "14","number": "1","pages": "24929","abstract": "During muscle contraction, not only are the fascicles shortening but also the pennation angle changes, which leads to a faster contraction of the muscle than of its fascicles. This phenomenon is called muscle gearing, and it has a direct influence on the force output of the muscle. There are few studies showing pennation angle changes during isometric and concentric contractions for different contraction intensities and muscle lengths. Therefore, the aim was to determine these influences over a wide range of contraction intensities and ankle joint angles for human triceps surae. Additionally, the influence of contraction intensity and ankle joint angle on muscle gearing was evaluated. Ten sport students performed concentric and isometric contractions with intensities between 0 and 90\\% of the maximum voluntary contraction and ankle joint angles from 50° to 120°. During these contractions, the m. gastrocnemius medialis and lateralis and the m. soleus were recorded via ultrasound imaging. A nonlinear relationship between fascicle length and pennation angle was discovered, which can be described with a quadratic fit for each of the muscles during isometric contraction. A nearly identical relationship was detected during dynamic contraction. The muscle gearing increased almost linearly with contraction intensity and ankle joint angle.", "issn" : "2045-2322", "doi" : "10.1038/s41598-024-75795-2", "bibtexKey": "Coenning2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2a02e2ea2586fd20089b22f156738b3e0/inspo5", "tags" : [ "geometryfascicle","myown","curvaturephotogrammetric","pennationfascicle","lengthfascicle","reconstructionmuscle","Muscle","compartments" ], "intraHash" : "a02e2ea2586fd20089b22f156738b3e0", "interHash" : "665b863a52d2c8a3419188684061b167", "label" : "Influence of muscle packing on the three-dimensional architecture of rabbit M. plantaris", "user" : "inspo5", "description" : "", "date" : "2024-10-02 13:53:09", "changeDate" : "2024-10-02 13:53:09", "count" : 3, "pub-type": "article", "journal": "Journal of the Mechanical Behavior of Biomedical Materials","publisher":"Elsevier BV", "year": "2024", "url": "http://dx.doi.org/10.1016/j.jmbbm.2024.106762", "author": [ "Mischa Borsdorf","Stefan Papenkort","Markus Böl","Tobias Siebert" ], "authors": [ {"first" : "Mischa", "last" : "Borsdorf"}, {"first" : "Stefan", "last" : "Papenkort"}, {"first" : "Markus", "last" : "Böl"}, {"first" : "Tobias", "last" : "Siebert"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "pages": "106762","abstract": "In their physiological condition, muscles are surrounded by connective tissue, other muscles and bone. These tissues exert transverse forces that change the three-dimensional shape of the muscle compared to its isolated condition, in which all surrounding tissues are removed. A change in shape affects the architecture of a muscle and therefore its mechanical properties. The rabbit M. plantaris is a multi-pennate calf muscle consisting of two compartments. A smaller, bi-pennate inner muscle compartment is embedded in a larger, uni-pennate outer compartment (\r\nBöl et al., 2015\r\n). As part of the calf, the plantaris is tightly packed between other muscles. It is unclear how packing affects the shape and architecture of the plantaris. Therefore, we examined the isolated and packed plantaris of the contralateral legs of three rabbits to determine the influence of the surrounding muscles on its shape and architectural properties using photogrammetric reconstruction and manual digitization, respectively. In the packed condition, the plantaris showed a 27% increase in fascicle pennation and a 54% increase in fascicle curvature compared to the isolated condition. Fascicle length was not affected by muscle packing. The change in muscle architecture occurred mainly in the outer compartment of the plantaris. Furthermore, the isolated plantaris showed a more circular shape and a reduced width of its muscle belly. It can be concluded that the packed plantaris is flattened by the forces exerted by the surrounding muscles, causing a complex architectural change. The data provided improve our understanding of muscle packages in general and can be used to develop and validate realistic three-dimensional muscle models.", "language" : "English", "issn" : "1751-6161", "doi" : "10.1016/j.jmbbm.2024.106762", "bibtexKey": "Borsdorf_2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2c7e68ae5f3894d810752300311254ade/inspo5", "tags" : [ "lengthening","Active","Force-length","Force-velocity","relation","Benchmark","LS-DYNA","Muscle","model","Impedance" ], "intraHash" : "c7e68ae5f3894d810752300311254ade", "interHash" : "f87d2c872f2e6f474113b724ada23083", "label" : "A benchmark of muscle models to length changes great and small", "user" : "inspo5", "description" : " linked to Projekt Adires", "date" : "2024-09-24 16:36:35", "changeDate" : "2025-02-11 20:19:56", "count" : 16, "pub-type": "article", "journal": "ScienceDirect Elsevier", "year": "2024", "url": "https://www.sciencedirect.com/science/article/pii/S1751616124003722?via%3Dihub", "author": [ "Matthew Millard","Norman Stutzig","Jörg Fehr","Tobias Siebert" ], "authors": [ {"first" : "Matthew", "last" : "Millard"}, {"first" : "Norman", "last" : "Stutzig"}, {"first" : "Jörg", "last" : "Fehr"}, {"first" : "Tobias", "last" : "Siebert"} ], "abstract": "Digital human body models are used to simulate injuries that occur as a result of vehicle collisions, vibration, sports, and falls. Given enough time the body\u2019s musculature can generate force, affect the body\u2019s movements, and change the risk of some injuries. The finite-element code LS-DYNA is often used to simulate the movements and injuries sustained by the digital human body models as a result of an accident. In this work, we evaluate the accuracy of the three muscle models in LS-DYNA (MAT_156, EHTM, and the VEXAT) when simulating a range of experiments performed on isolated muscle: force-length-velocity experiments on maximally and sub-maximally stimulated muscle, active-lengthening experiments, and vibration experiments. The force-length-velocity experiments are included because these conditions are typical of the muscle activity that precedes an accident, while the active-lengthening and vibration experiments mimic conditions that can cause injury. The three models perform similarly during the maximally and sub-maximally activated force-length-velocity experiments, but noticeably differ in response to the active-lengthening and vibration experiments. The VEXAT model is able to generate the enhanced forces of biological muscle during active lengthening, while both the MAT_156 and EHTM produce too little force. In response to vibration, the stiffness and damping of the VEXAT model closely follows the experimental data while the MAT_156 and EHTM models differ substantially. The accuracy of the VEXAT model comes from two additional mechanical structures that are missing in the MAT_156 and EHTM models: viscoelastic cross-bridges, and an active titin filament. To help others build on our work we have made our simulation code publicly available.", "language" : "English", "doi" : "10.1016/j.jmbbm.2024.106740", "bibtexKey": "millard2024benchmark" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/213d1c527b422f0c2fbfb26d98885b1f6/inspo5", "tags" : [ "Blebbistatin","damping","Cross-bridge","Mechanosensing","Signaling","Mechanical","Contractile","power","Muscle","behaviour","block","Sarcomere" ], "intraHash" : "13d1c527b422f0c2fbfb26d98885b1f6", "interHash" : "1a1ddb22b3fc4a98ff638b17f957aa71", "label" : "Force re-development after shortening reveals a role for titin in stretch-shortening performance enhancement in skinned muscle fibres", "user" : "inspo5", "description" : "", "date" : "2024-08-28 13:42:24", "changeDate" : "2025-02-11 20:09:58", "count" : 6, "pub-type": "article", "journal": "Journal of Experimental Biology","publisher":"The Company of Biologists", "year": "2024", "url": "http://dx.doi.org/10.1242/jeb.247377", "author": [ "André Tomalka","Sven Weidner","Daniel Hahn","Wolfgang Seiberl","Tobias Siebert" ], "authors": [ {"first" : "André", "last" : "Tomalka"}, {"first" : "Sven", "last" : "Weidner"}, {"first" : "Daniel", "last" : "Hahn"}, {"first" : "Wolfgang", "last" : "Seiberl"}, {"first" : "Tobias", "last" : "Siebert"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "abstract": "Stretch-shortening cycles (SSCs) involve muscle lengthening (eccentric contractions) instantly followed by shortening (concentric contractions). This combination enhances force, work, and power output compared to pure shortening (SHO), which is known as SSC-effect. Recent evidence indicates both cross-bridge-based (XB) and non-cross-bridge-based (non-XB, e.g., titin) structures contribute to this effect. This study analyzed force re-development following SSCs and SHO to gain further insight into the roles of XB and non-XB structures regarding the SSC-effect. Experiments were conducted on rat soleus muscle fibres (n=16) with different SSC velocities (30%, 60%, 85% of maximum shortening velocity) and constant stretch-shortening magnitudes (18% of optimum length). The XB inhibitor blebbistatin was used to distinguish between XB and non-XB contributions to force generation. Results showed SSCs led to significantly greater (1.02±.15 vs. 0.68±.09 [ΔF/Δt]; t(62)=8.61, p<.001, d=2.79) and faster (75 ms vs. 205 [ms]; t(62) = -6.37, p<.001, d=-1.48) force re-development compared to SHO in the control treatment. In the blebbistatin treatment, SSCs still resulted in greater (.11±.03 vs. .06±.01 [ΔF/Δt]; t(62) = 8.00, p<.001, d=2.24) and faster (3010±1631 vs. 7916±3230 [ms]; t(62) = -8.00, p<.001, d=-1.92) force re-development compared to SHO. These findings deepen our understanding of the SSC-effect, underscoring the involvement of non-XB structures like titin in modulating force production. This modulation likely involves complex mechanosensory coupling from stretch to signal transmission during muscle contraction.", "issn" : "1477-9145", "doi" : "10.1242/jeb.247377", "bibtexKey": "Tomalka_2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/23703361ba5364a5c2d4588e2de1b7f6e/inspo5", "tags" : [ "Give","Soleus","muscle","Contractile","Stretch","behavior","Skeletal" ], "intraHash" : "3703361ba5364a5c2d4588e2de1b7f6e", "interHash" : "91b7f9a1d1c44b2548f31012f256c179", "label" : "Impact of lengthening velocity on the generation of eccentric force by slow-twitch muscle fibers in long stretches", "user" : "inspo5", "description" : "", "date" : "2024-07-29 15:08:26", "changeDate" : "2025-02-03 10:59:12", "count" : 6, "pub-type": "article", "journal": "Pfluegers Archiv - European Journal of Physiology", "year": "2024", "url": "https://doi.org/10.1007/s00424-024-02991-4", "author": [ "Sven Weidner","André Tomalka","Christian Rode","Tobias Siebert" ], "authors": [ {"first" : "Sven", "last" : "Weidner"}, {"first" : "André", "last" : "Tomalka"}, {"first" : "Christian", "last" : "Rode"}, {"first" : "Tobias", "last" : "Siebert"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "abstract": "After an initial increase, isovelocity elongation of a muscle fiber can lead to diminishing (referred to as Give in the literature) and subsequently increasing force. How the stretch velocity affects this behavior in slow-twitch fibers remains largely unexplored. Here, we stretched fully activated individual rat soleus muscle fibers from 0.85 to 1.3 optimal fiber length at stretch velocities of 0.01, 0.1, and 1 maximum shortening velocity, vmax, and compared the results with those of rat EDL fast-twitch fibers obtained in similar experimental conditions. In soleus muscle fibers, Give was 7\\%, 18\\%, and 44\\% of maximum isometric force for 0.01, 0.1, and 1 vmax, respectively. As in EDL fibers, the force increased nearly linearly in the second half of the stretch, although the number of crossbridges decreased, and its slope increased with stretch velocity. Our findings are consistent with the concept of a forceful detachment and subsequent crossbridge reattachment in the stretch's first phase and a strong viscoelastic titin contribution to fiber force in the second phase of the stretch. Interestingly, we found interaction effects of stretch velocity and fiber type on force parameters in both stretch phases, hinting at fiber type-specific differences in crossbridge and titin contributions to eccentric force. Whether fiber type-specific combined XB and non-XB models can explain these effects or if they hint at some not fully understood properties of muscle contraction remains to be shown. These results may stimulate new optimization perspectives in sports training and provide a better understanding of structure--function relations of muscle proteins.", "issn" : "1432-2013", "doi" : "10.1007/s00424-024-02991-4", "bibtexKey": "Weidner2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/21c09ad3a57d45986105107c77d0da5cf/inspo5", "tags" : [ "3d","image","fibres","shape","muscle","deformation","processing","contraction","dynamic","movement","ultrasound" ], "intraHash" : "1c09ad3a57d45986105107c77d0da5cf", "interHash" : "539e1f9768e937f368f3546f4de55813", "label" : "Determination of muscle shape deformations of the tibialis anterior during dynamic contractions using 3D ultrasound", "user" : "inspo5", "description" : "", "date" : "2024-07-05 14:59:56", "changeDate" : "2024-07-18 11:02:59", "count" : 7, "pub-type": "article", "journal": "Frontiers in Bioengineering and Biotechnology", "year": "2024", "url": "https://www.frontiersin.org/articles/10.3389/fbioe.2024.1388907", "author": [ "Annika S. Sahrmann","Lukas Vosse","Tobias Siebert","Geoffrey G. Handsfield","Oliver Röhrle" ], "authors": [ {"first" : "Annika S.", "last" : "Sahrmann"}, {"first" : "Lukas", "last" : "Vosse"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Geoffrey G.", "last" : "Handsfield"}, {"first" : "Oliver", "last" : "Röhrle"} ], "volume": "12", "issn" : "2296-4185", "doi" : "10.3389/fbioe.2024.1388907", "bibtexKey": "Sahrmann2024c" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2bdb55aca3ae7eac8dc1d01764e0773a3/inspo5", "tags" : [ "stretch","muscle-tendon","siebert","unit","muscle","Eccentric","action","active","stretch-shortening","cycle" ], "intraHash" : "bdb55aca3ae7eac8dc1d01764e0773a3", "interHash" : "ded4877e88b626fe8d1872f00b7a2a53", "label" : "Unlocking the benefit of active stretch: The Eccentric muscle action not the preload maximizes muscle-tendon unit stretch-shortening cycle performance", "user" : "inspo5", "description" : "", "date" : "2024-07-01 13:13:24", "changeDate" : "2024-07-01 13:13:24", "count" : 2, "pub-type": "article", "journal": "Journal of Applied Physiology","publisher":"American Physiological Society", "year": "2024", "url": "http://dx.doi.org/10.1152/japplphysiol.00809.2023", "author": [ "Tobias Goecking","Denis Holzer","Daniel Hahn","Tobias Siebert","Wolfgang Seiberl" ], "authors": [ {"first" : "Tobias", "last" : "Goecking"}, {"first" : "Denis", "last" : "Holzer"}, {"first" : "Daniel", "last" : "Hahn"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Wolfgang", "last" : "Seiberl"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "abstract": "Stretch-shortening cycles (SSCs) outperform shortening contractions preceded by isometric contractions in terms of enhanced force/torque, work, and power production during shortening. This so-called SSC-effect is presumably related to the active muscle stretch before shortening in SSCs. However, it remains unclear whether the stretch-induced higher preload level or stretch-induced history dependence effects maximize the SSC-effect. Therefore, we analyzed fascicle behavior, MTU shortening work, and torque/force (N=12 participants) via ultrasound and dynamometry during electrically stimulated submaximal plantar flexion contractions from 10° plantarflexion to 15° dorsiflexion. To elucidate the effects of preload level and preload modality (i.e. contraction type) on shortening performance, muscle-tendon unit shortening was preceded by fixed-end (SHO), active stretch (SSC), and preload-matched fixed-end (MATCHED) contractions. Prior to shortening MATCHED and SCC had the same preload level (1% torque difference), similar joint position and muscle fascicle lengths. Compared with SHO, shortening work was significantly (p<.001, partial η2=.749) increased by 85% and 55% for SSC and MATCHED, respectively, with SSC shortening work being significantly higher than MATCHED (p=.016). This indicates that preload contributes by 65% to the overall SSC-effect, so that 35 % need to be referred to stretched-induced history dependent mechanisms. Additionally, SSC showed larger fascicle forces at the end of shortening (p<.001) and 20% less depressed isometric torque following shortening compared with MATCHED (p<.001). Since potential decoupling effects by the series elastic element were controlled by matching the preload levels, we conclude that the difference between SSC and MATCHED is related to stretch-induced long-lasting history dependent effects.", "language" : "English", "issn" : "1522-1601", "doi" : "10.1152/japplphysiol.00809.2023", "bibtexKey": "Goecking_2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/21947549f0f7295e064e79f467f085d7b/inspo5", "tags" : [ "3D","image","muscle","deformation","processing","contraction","dynamic","movement","ultrasound" ], "intraHash" : "1947549f0f7295e064e79f467f085d7b", "interHash" : "277676c63d8a348032cb6102b6abeb37", "label" : "Determination of muscle shape deformations of the tibialis anterior during dynamic contractions using 3D ultrasound.\r\nFront. Bioeng. Biotechnol. 12:1388907.", "user" : "inspo5", "description" : "", "date" : "2024-06-05 15:26:27", "changeDate" : "2024-07-16 12:38:53", "count" : 3, "pub-type": "article", "journal": "Frontiers in Bioengineering and Biotechnology", "year": "2024", "url": "https://www.frontiersin.org/articles/10.3389/fbioe.2024.1388907/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Bioengineering_and_Biotechnology&id=1388907", "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "12","abstract": "Purpose: In this paper, we introduce a novel method for determining 3D deformations of the human tibialis anterior (TA) muscle during dynamic movements using 3D ultrasound.\r\n\r\nMaterials and Methods: An existing automated 3D ultrasound system is used for data acquisition, which consists of three moveable axes, along which the probe can move. While the subjects perform continuous plantar- and dorsiflexion movements in two different controlled velocities, the ultrasound probe sweeps cyclically from the ankle to the knee along the anterior shin. The ankle joint angle can be determined using reflective motion capture markers. Since we considered the movement direction of the foot, i.e., active or passive TA, four conditions occur: slow active, slow passive, fast active, fast passive. By employing an algorithm which defines ankle joint angle intervals, i.e., intervals of range of motion (ROM), 3D images of the volumes during movement can be reconstructed.\r\n\r\nResults: We found constant muscle volumes between different muscle lengths, i.e., ROM intervals. The results show an increase in mean cross-sectional area (CSA) for TA muscle shortening. Furthermore, a shift in maximum CSA towards the proximal side of the muscle could be observed for muscle shortening. We found significantly different maximum CSA values between the fast active and all other conditions, which might be caused by higher muscle activation due to the faster velocity.\r\n\r\nConclusion: In summary, we present a method for determining muscle volume deformation during dynamic contraction using ultrasound, which will enable future empirical studies and 3D computational models of skeletal muscles.", "language" : "English", "doi" : "10.3389/fbioe.2024.1388907", "bibtexKey": "siebert2024determination" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/283fba02b010557af3f547c378cdb6de6/inspo5", "tags" : [ "fiber","Intramuscular","tissue","matrix","Extracellular","integrity","transmission","Endomysium","Connective","Muscle","force" ], "intraHash" : "83fba02b010557af3f547c378cdb6de6", "interHash" : "2d12b002242e8974ec406082ad65e8b3", "label" : "Endomysium determines active and passive force production in muscle fibers", "user" : "inspo5", "description" : "", "date" : "2024-05-08 11:25:57", "changeDate" : "2024-08-07 11:33:21", "count" : 8, "pub-type": "article", "journal": "Journal of Biomechanics","publisher":"Elsevier BV", "year": "2024", "url": "http://dx.doi.org/10.1016/j.jbiomech.2024.112134", "author": [ "Paolo Carlo Danesini","Maximilian Heim","André Tomalka","Tobias Siebert","Filiz Ates" ], "authors": [ {"first" : "Paolo", "last" : "Carlo Danesini"}, {"first" : "Maximilian", "last" : "Heim"}, {"first" : "André", "last" : "Tomalka"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Filiz", "last" : "Ates"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "168","pages": "112134","abstract": "Connective tissues can be recognized as an important structural support element in muscles. Recent studies have also highlighted its importance in active force generation and transmission between muscles, particularly through the epimysium. In the present study, we aimed to investigate the impact of the endomysium, the connective tissue surrounding muscle fibers, on both passive and active force production. Pairs of skeletal muscle fibers were extracted from the extensor digitorum longus muscles of rats and, after chemical skinning, their passive and active force\u2013length relationships were measured under two conditions: (i) with the endomysium between muscle fibers intact, and (ii) after its dissection. We found that the dissection of the endomysium caused force to significantly decrease in both active (by 22.2 % when normalized to the maximum isometric force; p < 0.001) and passive conditions (by 25.9 % when normalized to the maximum isometric force; p = 0.034). These findings indicate that the absence of endomysium compromises muscle fiber\u2019s not only passive but also active force production. This effect may be attributed to increased heterogeneity in sarcomere lengths, enhanced lattice spacing between myofilaments, or a diminished role of trans-sarcolemmal proteins due to dissecting the endomysium. Future investigations into the underlying mechanisms and their implications for various extracellular matrix-related diseases are warranted.", "language" : "English", "issn" : "0021-9290", "doi" : "10.1016/j.jbiomech.2024.112134", "bibtexKey": "Carlo_Danesini_2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/29fc3cfecc2c39e52b98d0b7689d90927/inspo5", "tags" : [ "myown","Passive","strength","isometric","muscle","of","motion","range" ], "intraHash" : "9fc3cfecc2c39e52b98d0b7689d90927", "interHash" : "c80ddfcaf1910d1f46a38466df87a8f6", "label" : "Reference measures of lower-limb joint range of motion, muscle strength, and selective voluntary motor control of typically developing children aged 5\u201317 years", "user" : "inspo5", "description" : "", "date" : "2024-05-07 14:33:56", "changeDate" : "2024-08-07 11:29:43", "count" : 6, "pub-type": "article", "journal": "Journal of Children\u2019s Orthopaedics","publisher":"SAGE Publications", "year": "2024", "url": "http://dx.doi.org/10.1177/18632521241234768", "author": [ "Emily Scherff","Sabrina Elisabeth Schnell","Tobias Siebert","Sonia D\u2019Souza" ], "authors": [ {"first" : "Emily", "last" : "Scherff"}, {"first" : "Sabrina Elisabeth", "last" : "Schnell"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Sonia", "last" : "D\u2019Souza"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "pages": "1-10","abstract": "Background:\r\nJoint range of motion based on the neutral null method, muscle strength based on manual muscle testing, and selective voluntary motor control based on selective control assessment of the lower extremity are standard parameters of a pediatric three-dimensional clinical gait analysis. Lower-limb reference data of children are necessary to identify and quantify abnormalities, but these are limited and when present restricted to specific joints or muscles.\r\nMethods:\r\nThis is the first study that encompasses the aforementioned parameters from a single group of 34 typically developing children aged 5\u201317\u2009years. Left and right values were averaged for each participant, and then the mean and standard deviation calculated for the entire sample. The data set was tested for statistical significance (p\u2009<\u20090.05).\r\nResults:\r\nJoint angle reference values are mostly consistent with previously published standards, although there is a large variability in the existing literature. All muscle strength distributions, except for M. quadriceps femoris, differ significantly from the maximum value of 5. The mean number of repetitions of heel-rise test is 12\u2009±\u20095. Selective voluntary motor control shows that all distributions, except for M. quadriceps femoris, differ significantly from the maximum value of 2.\r\nConclusion:\r\nSince typically developing children do not match expectations and reference values from the available literature and clinical use, this study emphasizes the importance of normative data. Excessively high expectations lead to typically developing children being falsely underestimated and affected children being rated too low. This is of great relevance for therapists and clinicians.", "language" : "English", "issn" : "1863-2548", "doi" : "10.1177/18632521241234768", "bibtexKey": "Scherff_2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2d627d1373c83b8831d4db9c14e3feadb/inspo5", "tags" : [ "Image","Skeletal","ultrasound","3D","Inspo","PN2-8","Pennation","muscle","angle","processing","Siebert","architecture" ], "intraHash" : "d627d1373c83b8831d4db9c14e3feadb", "interHash" : "98fb95294493de86e2fff35735a2a27a", "label" : "3D ultrasound-based determination of skeletal muscle fascicle orientations", "user" : "inspo5", "description" : "", "date" : "2024-04-02 12:17:45", "changeDate" : "2024-07-16 12:43:09", "count" : 5, "pub-type": "article", "journal": "Biomechanics and Modeling in Mechanobiology", "year": "2024", "url": "https://doi.org/10.1007/s10237-024-01837-3", "author": [ "Annika S. Sahrmann","Lukas Vosse","Tobias Siebert","Geoffrey G. Handsfield","Oliver Röhrle" ], "authors": [ {"first" : "Annika S.", "last" : "Sahrmann"}, {"first" : "Lukas", "last" : "Vosse"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Geoffrey G.", "last" : "Handsfield"}, {"first" : "Oliver", "last" : "Röhrle"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "abstract": "Architectural parameters of skeletal muscle such as pennation angle provide valuable information on muscle function, since they can be related to the muscle force generating capacity, fiber packing, and contraction velocity. In this paper, we introduce a 3D ultrasound-based workflow for determining 3D fascicle orientations of skeletal muscles. We used a custom-designed automated motor driven 3D ultrasound scanning system for obtaining 3D ultrasound images. From these, we applied a custom-developed multiscale-vessel enhancement filter-based fascicle detection algorithm and determined muscle volume and pennation angle. We conducted trials on a phantom and on the human tibialis anterior (TA) muscle of 10 healthy subjects in plantarflexion (157 ± 7\\$\\$^\\backslashcirc\\$\\$), neutral position (109 ± 7\\$\\$^\\backslashcirc\\$\\$, corresponding to neutral standing), and one resting position in between (145 ± 6\\$\\$^\\backslashcirc\\$\\$). The results of the phantom trials showed a high accuracy with a mean absolute error of 0.92 ± 0.59\\$\\$^\\backslashcirc\\$\\$. TA pennation angles were significantly different between all positions for the deep muscle compartment; for the superficial compartment, angles are significantly increased for neutral position compared to plantarflexion and resting position. Pennation angles were also significantly different between superficial and deep compartment. The results of constant muscle volumes across the 3 ankle joint angles indicate the suitability of the method for capturing 3D muscle geometry. Absolute pennation angles in our study were slightly lower than recent literature. Decreased pennation angles during plantarflexion are consistent with previous studies. The presented method demonstrates the possibility of determining 3D fascicle orientations of the TA muscle in vivo.", "issn" : "1617-7940", "doi" : "10.1007/s10237-024-01837-3", "bibtexKey": "Sahrmann2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2d99121cf0e4d2bfa7c185360a86e038b/inspo5", "tags" : [ "area","Inspo","siebert","Aponeurosis","pennation","geometry","length","Muscle","compartments","Fascicle","curvature" ], "intraHash" : "d99121cf0e4d2bfa7c185360a86e038b", "interHash" : "816781b7dca07a6982acaabf86b1f62f", "label" : "Influence of muscle length on the three-dimensional architecture and aponeurosis dimensions of rabbit calf muscles", "user" : "inspo5", "description" : "", "date" : "2024-04-02 12:06:57", "changeDate" : "2024-04-02 12:06:57", "count" : 2, "pub-type": "article", "journal": "Journal of the Mechanical Behavior of Biomedical Materials","publisher":"Elsevier BV", "year": "2024", "url": "http://dx.doi.org/10.1016/j.jmbbm.2024.106452", "author": [ "Mischa Borsdorf","Stefan Papenkort","Markus Böl","Tobias Siebert" ], "authors": [ {"first" : "Mischa", "last" : "Borsdorf"}, {"first" : "Stefan", "last" : "Papenkort"}, {"first" : "Markus", "last" : "Böl"}, {"first" : "Tobias", "last" : "Siebert"} ], "editor": [ "Tobias Siebert" ], "editors": [ {"first" : "Tobias", "last" : "Siebert"} ], "volume": "152","pages": "106452","abstract": "The function of a muscle is highly dependent on its architecture, which is characterized by the length, pennation, and curvature of the fascicles, and the geometry of the aponeuroses. During in vivo function, muscles regularly undergo changes in length, thereby altering their architecture. During passive muscle lengthening, fascicle length (FL) generally increases and the angle of fascicle pennation (FP) and the fascicle curvature (FC) decrease, while the aponeuroses increase in length but decrease in width.\r\n\r\nMuscles are differently structured, making their change during muscle lengthening complex and multifaceted. To obtain comprehensive data on architectural changes in muscles during passive length, the present study determined the three-dimensional fascicle geometry of rabbit M. gastrocnemius medialis (GM), M. gastrocnemius lateralis (GL), and M. plantaris (PLA). For this purpose, the left and right legs of three rabbits were histologically fixed at targeted ankle joint angles of 95° (short muscle length [SML]) and 60° (long muscle length [LML]), respectively, and the fascicles were tracked by manual three-dimensional digitization. In a second set of experiments, the GM aponeurosis dimensions of ten legs from five rabbits were determined at varying muscle lengths via optical marker tracking.\r\n\r\nThe GM consisted of a uni-pennated compartment, whereas the GL and PLA contained multiple compartments of differently pennated fascicles. In the LML compared to the SML, the GM, GL, and PLA had on average a 41%, 29%, and 41% increased fascicle length, and a 30%, 25%, and 33% decrease in fascicle pennation and a 32%, 11%, and 35% decrease in fascicle curvature, respectively. Architectural properties were also differentiated among the different compartments of the PLA and GL, allowing for a more detailed description of their fascicle structure and changes. It was shown that the compartments change differently with muscle length. It was also shown that for each degree of ankle joint angle reduction, the proximal GM aponeurosis length increased by 0.11%, the aponeurosis width decreased by 0.22%, and the area was decreased by 0.20%. The data provided improve our understanding of muscles and can be used to develop and validate muscle models.", "language" : "English", "issn" : "1751-6161", "doi" : "10.1016/j.jmbbm.2024.106452", "bibtexKey": "Borsdorf_2024" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2e4e02c0109253f014eab6112890ec01a/inspo5", "tags" : [ "myown","fibers","skeletal","muscle" ], "intraHash" : "e4e02c0109253f014eab6112890ec01a", "interHash" : "6523cef4e6753682ec109909945c5d3c", "label" : "Ultrastructural and kinetic evidence support that thick filaments slide through the Z-disc", "user" : "inspo5", "description" : "", "date" : "2023-11-21 13:55:47", "changeDate" : "2024-07-05 14:43:40", "count" : 6, "pub-type": "article", "journal": "Interface : journal of the Royal Society","publisher":"The Royal Society", "year": "2022", "url": "https://royalsocietypublishing.org/doi/10.1098/rsif.2022.0642", "author": [ "André Tomalka","Maximilian Heim","Annika Klotz","Christian Rode","Tobias Siebert" ], "authors": [ {"first" : "André", "last" : "Tomalka"}, {"first" : "Maximilian", "last" : "Heim"}, {"first" : "Annika", "last" : "Klotz"}, {"first" : "Christian", "last" : "Rode"}, {"first" : "Tobias", "last" : "Siebert"} ], "volume": "19","number": "197","pages": "20220642","abstract": "How myofilaments operate at short mammalian skeletal muscle lengths is unknown. A common assumption is that thick (myosin-containing) filaments get compressed at the Z-disc. We provide ultrastructural evidence of sarcomeres contracting down to 0.44 µm\u2014approximately a quarter of thick filament resting length\u2014in long-lasting contractions while apparently keeping a regular, parallel thick filament arrangement. Sarcomeres produced force at such extremely short lengths. Furthermore, sarcomeres adopted a bimodal length distribution with both modes below lengths where sarcomeres are expected to generate force in classic force\u2013length measurements. Mammalian fibres did not restore resting length but remained short after deactivation, as previously reported for amphibian fibres, and showed increased forces during passive re-elongation. These findings are incompatible with viscoelastic thick filament compression but agree with predictions of a model incorporating thick filament sliding through the Z-disc. This more coherent picture of mechanical mammalian skeletal fibre functioning opens new perspectives on muscle physiology", "research-areas" : "Science & Technology - Other Topics", "language" : "eng", "issn" : "1742-5689 and 1742-5662", "affiliation" : "Tomalka, A (Corresponding Author), Univ Stuttgart, Mot & Exercise Sci, Stuttgart, Germany.\r\n Tomalka, A (Corresponding Author), Univ Stuttgart, Stuttgart Ctr Simulat Sci, Stuttgart, Germany.\r\n Tomalka, Andre; Heim, Maximilian; Klotz, Annika; Siebert, Tobias, Univ Stuttgart, Mot & Exercise Sci, Stuttgart, Germany.\r\n Tomalka, Andre; Heim, Maximilian; Klotz, Annika; Siebert, Tobias, Univ Stuttgart, Stuttgart Ctr Simulat Sci, Stuttgart, Germany.\r\n Rode, Christian, Univ Rostock, Inst Sport Sci, Dept Biomech, Rostock, Germany.", "unique-id" : "WOS:000894225300004", "doi" : "10.1098/rsif.2022.0642", "bibtexKey": "tomalka2022ultrastructural" } ] }