Properties of the muscle-tendon complex

Muscles have different functions in locomotion (e.g. motor, brake, spring). A sub-goal of this project is to verify whether there are adaptations of muscle parameters to these functions. For this purpose, different muscles are compared experimentally and by simulations of muscle contractions. The latter requires a muscle model that describes the history dependence of muscle force. For this purpose, we were able to develop a model that starts from physiological ideas (activation-dependent recruitment of the muscle filament titin) and allows for the first time the prediction of force enhancement and force depression in the correct order of magnitude (Rode et al. 2009).  Based on the modeling of the titin-actin interaction, realistic simulations of eccentric contractions over very long strain ranges at different start lengths could further be reproduced (Till et al. 2008, Till et al. 2010). In this application period, a necessary model extension regarding force reduction during muscle shortening will be performed. Based on this model extension, muscles will be compared with respect to their properties as motor, brake or spring.
Muscles are surrounded by other muscles and bones, which exert transverse forces on them. Another subgoal is to study the effects of these forces on contraction dynamics as a prerequisite for comparing the adaptations of different muscles in this regard. The model description of the reduction of muscle force (Siebert et al. 2012a, Siebert et al. 2012b) by transverse loading will be extended with the help of further experiments with respect to different transverse loads (e.g., impacts, variation of contact area). By combining this with a previously developed geometry model, a reduced 3D model for muscle deformation and contraction dynamics during transverse loading will be created. This could be used e.g. in medicine (prediction of functional effects of medical operations), prosthetics (optimization of prostheses) and accident research.
Muskeln sind von anderen Muskeln und Knochen umgeben, die transversale Kräfte auf sie ausüben. Ein weiteres Teilziel ist die Untersuchung der Auswirkungen dieser Kräfte auf die Kontraktionsdynamik als Voraussetzung für den Vergleich der diesbezüglichen Anpassungen verschiedener Muskeln. Die modellhafte Beschreibung der Reduktion der Muskelkraft (Siebert et al. 2012a, Siebert et al. 2012b) durch transversale Belastung soll mit Hilfe weiterer Experimente im Hinblick auf unterschiedliche transversale Belastungen (z.B. Stöße, Variation der Kontaktfläche) erweitert werden. Durch Kombination mit einem bereits entwickelten Geometriemodell soll ein reduziertes 3D Modell für Muskelverformung und Kontraktionsdynamik bei transversaler Belastung erstellt werden. Dieses konnte z.B. in der Medizin (Vorhersage funktioneller Auswirkungen medizinischer Operationen), der Prothetik (Optimierung von Prothesen) und der Unfallforschung verwendet werden.

Literatur

• Siebert, T., Tomalka, A., Stutzig, N., Leichsenring, K., & Bol, M. (2017). Changes in three-dimensional muscle structure of rabbit gastrocnemius, flexor digitorum longus, and tibialis anterior during growth. J Mech Behav Biomed Mater, 74, 507-519. [link]
• Siebert, T., Stutzig, N., & Rode, C. (2017). A hill-type muscle model expansion accounting for effects of varying transverse muscle load. J Biomech. [link]
• Heidlauf, T., Klotz, T., Rode, C., Siebert, T., & Rohrle, O. (2017). A continuum-mechanical skeletal muscle model including actin-titin interaction predicts stable contractions on the descending limb of the force-length relation. PLoS Comput Biol, 13(10), e1005773. doi:10.1371/journal.pcbi.1005773 [link]
• Tomalka A, Rode C, Schumacher J & Siebert T. (2017). The active force-length relationship is invisible during extensive eccentric contractions in skinned skeletal muscle fibres. Proc Biol Sci, 284. [link]
• Heidlauf T, Klotz T, Rode C, Altan E, Bleiler C, Siebert T & Rohrle O. (2016). A multi-scale continuum model of skeletal muscle mechanics predicting force enhancement based on actin-titin interaction. Biomech Model Mechanobiol 15, 1423-1437. [link]
• Reinhardt L, Siebert T, Leichsenring K, Blickhan R & Böl M. (2016). Intermuscular pressure between synergistic muscles correlates with muscle force. J Exp Biol 219, 2311-2319. [link]
• Rode C, Siebert T, Tomalka A & Blickhan R. (2016). Myosin filament sliding through the Z-disc relates striated muscle fibre structure to function. Proc R Soc B., 283. [link]
• Siebert T, Rode C, Till O, Stutzig N & Blickhan R. (2016). Force reduction induced by unidirectional transversal muscle loading is independent of local pressure. J Biomech. 49, 1156-1161. [link]
• Siebert T, Leichsenring K, Rode C, Wick C, Stutzig N, Schubert H, Blickhan R & Bol M. (2015). Three-Dimensional Muscle Architecture and Comprehensive Dynamic Properties of Rabbit Gastrocnemius, Plantaris and Soleus: Input for Simulation Studies. PLoS ONE 10, e0130985. [link]
• Morl F, Siebert T & Haufle D. (2015). Contraction dynamics and function of the muscle-tendon complex depend on the muscle fibre-tendon length ratio: a simulation study. Biomech Model Mechanobiol. DOI: 10.1007/s10237-015-0688-7   [link]
• Siebert T., Till O., Stutzig N., Günther M. & Blickhan R. (2014). Muscle force depends on the amount of transversal muscle loading.  J Biomech 47, 1822-1828.  [link]
• Till O., Siebert T., Blickhan R. (2014). Force depression decays during shortening in the medial gastrocnemius of the rat.   J Biomech  47, 1099-1103.  [link]
• Siebert T, Till O & Blickhan R. (2014). Work partitioning of transversally loaded muscle: experimentation and simulation.  Comput Methods Biomech Biomed Engin, 17, 217-229  [link
• Morl F, Siebert T, Schmitt S, Blickhan R & Gunther M. (2012). Electro-mechanical delay in Hill-type muscle models.  Journal of Mechanics in Medicine and Biology  12,18 pages. Doi: 10.1142/S0219519412500856.  [link]
• Muller R, Siebert T & Blickhan R. (2012). Muscle Preactivation Control: Simulation of Ankle Joint Adjustments at Touchdown During Running on Uneven Ground.  J Appl Biomech  28, 718-725.  [link]
• Maas R, Siebert T & Leyendecker S. (2012). On the relevance of structure preservation to simulations of muscle actuated movements.  Biomech Model Mechanobiol 11, 543-556.  [link]
• Till O, Siebert T & Blickhan R. (2010). A mechanism accounting for independence on starting length of tension increase in ramp stretches of active skeletal muscle at short half-sarcomere lengths.  J Theor Biol  266, 117-123.  [link]
• Rode C, Siebert T & Blickhan R. (2009). Titin-induced force enhancement and force depression: a 'sticky-spring' mechanism in muscle contractions?  J Theor Biol  259, 350-360.  [link]
• Rode C, Siebert T, Herzog W, & Blickhan R (2009). The effects of parallel and series elastic components on the active cat soleus force-length relationship.  Journal of Mechanics in Medicine and Biology, 9(1), 105-122.  [link]
• Till O, Siebert T, Rode C & Blickhan R. (2008). Characterization of isovelocity extension of activated muscle: a Hill-type model for eccentric contractions and a method for parameter determination.  J Theor Biol  255, 176-187.  [link]
• Siebert T, Rode C, Herzog W, Till O, Blickhan R (2008) Nonlinearities make a difference: comparison of two common Hill-type models with real muscle.  Biol Cybern 98 (2), 133-143.  [link]