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Authors: Christensen, Kasper B.
Günther, Michael
Schmitt, Syn
Siebert, Tobias
Title: Cross-bridge mechanics estimated from skeletal muscles’ work-loop responses to impacts in legged locomotion
Issue Date: 2021 Zeitschriftenartikel 12 Scientific reports 11 (2021), No. 23638
ISSN: 2045-2322
Abstract: Legged locomotion has evolved as the most common form of terrestrial locomotion. When the leg makes contact with a solid surface, muscles absorb some of the shock-wave accelerations (impacts) that propagate through the body. We built a custom-made frame to which we fixated a rat (Rattus norvegicus, Wistar) muscle (m. gastrocnemius medialis and lateralis: GAS) for emulating an impact. We found that the fibre material of the muscle dissipates between 3.5 and 23μJ ranging from fresh, fully active to passive muscle material, respectively. Accordingly, the corresponding dissipated energy in a half-sarcomere ranges between 10.4 and 68zJ, respectively. At maximum activity, a single cross-bridge would, thus, dissipate 0.6% of the mechanical work available per ATP split per impact, and up to 16% energy in common, submaximal, activities. We also found the cross-bridge stiffness as low as 2.2pNnm-1, which can be explained by the Coulomb-actuating cross-bridge part dominating the sarcomere stiffness. Results of the study provide a deeper understanding of contractile dynamics during early ground contact in bouncy gait.
Appears in Collections:10 Fakultät Wirtschafts- und Sozialwissenschaften

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