{ "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/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/2dda7c7842f8b627c739b615bde678e28/inspo5", "tags" : [ "joint","maximum","range","estimation","the","corresponding","muscle","of","Far","angle","working","force","TS","on" ], "intraHash" : "dda7c7842f8b627c739b615bde678e28", "interHash" : "12a4bf98a06f2d283088a3622f5e5b0d", "label" : "Considerations on the human Achilles tendon moment arm for in vivo triceps surae muscle--tendon unit force estimates", "user" : "inspo5", "description" : "", "date" : "2022-07-19 11:10:29", "changeDate" : "2022-07-19 09:10:56", "count" : 2, "pub-type": "article", "journal": "Scientific Reports", "year": "2020", "url": "https://doi.org/10.1038/s41598-020-76625-x", "author": [ "Denis Holzer","Florian Kurt Paternoster","Daniel Hahn","Tobias Siebert","Wolfgang Seiberl" ], "authors": [ {"first" : "Denis", "last" : "Holzer"}, {"first" : "Florian Kurt", "last" : "Paternoster"}, {"first" : "Daniel", "last" : "Hahn"}, {"first" : "Tobias", "last" : "Siebert"}, {"first" : "Wolfgang", "last" : "Seiberl"} ], "volume": "10","number": "1","pages": "19559","abstract": "Moment arm-angle functions (MA-a-functions) are commonly used to estimate in vivo muscle forces in humans. However, different MA-a-functions might not only influence the magnitude of the estimated muscle forces but also change the shape of the muscle's estimated force-angle relationship (F-a-r). Therefore, we investigated the influence of different literature based Achilles tendon MA-a-functions on the triceps surae muscle--tendon unit F-a-r. The individual in vivo triceps torque--angle relationship was determined in 14 participants performing maximum voluntary fixed-end plantarflexion contractions from 18.3°þinspace±þinspace3.2° plantarflexion to 24.2°þinspace±þinspace5.1° dorsiflexion on a dynamometer. The resulting F-a-r were calculated using 15 literature-based in vivo Achilles tendon MA-a-functions. MA-a-functions affected the F-a-r shape and magnitude of estimated peak active triceps muscle--tendon unit force. Depending on the MA-a-function used, the triceps was solely operating on the ascending limb (nþinspace=þinspace2), on the ascending limb and plateau region (nþinspace=þinspace12), or on the ascending limb, plateau region and descending limb of the F-a-r (nþinspace=þinspace1). According to our findings, the estimated triceps muscle--tendon unit forces and the shape of the F-a-r are highly dependent on the MA-a-function used. As these functions are affected by many variables, we recommend using individual Achilles tendon MA-a-functions, ideally accounting for contraction intensity-related changes in moment arm magnitude.", "issn" : "2045-2322", "doi" : "10.1038/s41598-020-76625-x", "bibtexKey": "Holzer2020" } ] }