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Muscle-spring dynamics in time-limited, elastic movements.
M V Rosario1, G P Sutton2, S N Patek3
1Department of Biology, Duke University, Durham, NC 27708, USA michael_rosario@brown.edu.
Proceedings. Biological Sciences
|September 16, 2016
Summary
Animals with limited time for muscle contraction, like bullfrogs, maximize elastic energy storage with lower spring stiffness. This contrasts with time-unlimited animals, like grasshoppers, optimizing energy storage with higher stiffness for powerful jumps.
Area of Science:
- Biomechanics
- Evolutionary biology
- Animal locomotion
Background:
- Muscle-spring systems store elastic energy for locomotion.
- Time constraints can limit muscle force production during rapid movements.
- Evolutionary adaptations in biological springs (tendons, apodemes) are crucial for locomotion.
Purpose of the Study:
- To investigate if animals with time-limited muscle contractions use spring systems tuned for submaximal force.
- To compare elastic energy storage in time-limited (bullfrog) and non-time-limited (grasshopper) muscle-spring systems.
- To understand the role of muscle dynamics and behavioral constraints in optimizing energy storage.
Main Methods:
- A dynamic model of a muscle-spring system with fixed-end contraction was employed.
- Parameters from bullfrog (Lithobates catesbeiana) and grasshopper (Schistocerca gregaria) were used.
- Model simulations analyzed elastic energy storage under varying time constraints and spring stiffness.
Main Results:
- Maximal elastic energy storage is achieved with lower spring stiffness when muscle contraction time is limited.
- Bullfrog tendon stiffness, relevant to jump times (50 ms), maximized elastic energy storage.
- Grasshopper spring stiffness maximized energy storage under modeled maximal muscle contraction, reflecting no time limitation.
Conclusions:
- Evolutionary variations in tendon and apodeme properties are significant for realistic jumping performance.
- Muscle dynamics and behavioral constraints critically influence energy storage in biological muscle-spring systems.
- The tuning of biological springs is context-dependent, balancing speed and force for effective locomotion.
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