Berlin 2015 – scientific programme
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BP: Fachverband Biologische Physik
BP 37: Modelling of non-linear dynamics in biological movement (focus session)
BP 37.5: Talk
Wednesday, March 18, 2015, 16:15–16:30, EW 202
Wobbling masses: definite costs and potential benefits — •Michael Günther1,3 and Syn Schmitt1,2 — 1Universität Stuttgart, Human Movement Simulation Lab — 2Stuttgart Research Centre for Simulation Technology — 3Friedrich-Schiller-Universität Jena, Lehrstuhl für Bewegungswissenschaft
Humans seem biomechanically unique in the animal kingdom. It is, though, certainly neither bipedalism nor the strung-out leg that constitutes human's uniqueness. Some birds can even sleep on just one extended leg. Rather, it is the amount of muscle mass in the legs that makes humans unique animals. Muscle masses are soft tissue attached to the skeleton. They "wobble" when the bones are mechanically excited by impacts. Macroscopic units of soft tissue can be modelled as rigid bodies ("wobbling masses") interacting visco-elastically with the skeleton. As the corresponding energy dissipation is expected to roughly scale with wobbling mass volume, we examined how much energy is actually dissipated by human wobbling masses after a leg impact. We calculated numbers from wobbling mass kinematics of the stance leg, estimated on the basis of high-speed camera sequences of human running. Comparing dissipated energy to axial leg work and joint energy balances during ground contact provides a measure of relevance for the irreversible energy loss by leg wobbling masses. We discuss functional explanations for such a unique amount of wobbling masses in human legs. We also try and explain how they yet pay off although any significant amount of irreversible energy loss would seem inefficient and thus expectably avoided by nature as good as possible.