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Updated: Oct 21, 2025

Author Spotlight: Bridging the Gap Between In Vivo and Ex Vivo Studies with the "Avatar" Technique to Advance Muscle Mechanics Research
Published on: August 18, 2023
Muscle-specific economy of force generation and efficiency of work production during human running
Sebastian Bohm1,2, Falk Mersmann1,2, Alessandro Santuz1,2
1Humboldt-Universität zu Berlin, Department of Training and Movement Sciences, Berlin, Germany.
Abstract:
Human running features a spring-like interaction of body and ground, enabled by elastic tendons that store mechanical energy and facilitate muscle operating conditions to minimize the metabolic cost. By experimentally assessing the operating conditions of two important muscles for running, the soleus and vastus lateralis, we investigated physiological mechanisms of muscle work production and muscle force generation. We found that the soleus continuously shortened throughout the stance phase, operating as work generator under conditions that are considered optimal for work production: high force-length potential and high enthalpy efficiency. The vastus lateralis promoted tendon energy storage and contracted nearly isometrically close to optimal length, resulting in a high force-length-velocity potential beneficial for economical force generation. The favorable operating conditions of both muscles were a result of an effective length and velocity-decoupling of fascicles and muscle-tendon unit, mostly due to tendon compliance and, in the soleus, marginally by fascicle rotation.
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