Muscle–spring dynamics in time-limited, elastic movements

Rosario, Michael and Sutton, Gregory and Patek, Sheila and Sawicki, Gregory (2016) Muscle–spring dynamics in time-limited, elastic movements. Proceedings of the Royal Society B: Biological Sciences, 283 (1838). ISSN 0962-8452

Full content URL: https://doi.org/10.1098/rspb.2016.1561

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Abstract

Muscle contractions that load in-series springs with slow speed over a long duration do maximal work and store the most elastic energy. However, time constraints, such as those experienced during escape and predation behaviours, may prevent animals from achieving maximal force capacity from their muscles during spring-loading. Here, we ask whether animals that have limited time for elastic energy storage operate with springs that are tuned to submaximal force production. To answer this question, we used a dynamic model of a muscle–spring system undergoing a fixed-end contraction, with parameters from a time-limited spring-loader (bullfrog: Lithobates catesbeiana) and a non-time-limited spring-loader (grasshopper: Schistocerca gregaria).We found that when muscles have less time to contract, stored elastic energy is maximized with lower spring stiffness (quantified as spring constant). The spring stiffness measured in bullfrog tendons permitted less elastic energy storage than was predicted by a modelled, maximal muscle
contraction.However,whenmuscle contractionswere modelled using biologically relevant loading times for bullfrog jumps (50 ms), tendon stiffness actually maximized elastic energy storage. In contrast, grasshoppers, which are not time limited, exhibited spring stiffness that maximized elastic energy storage when modelled with a maximal muscle contraction. These findings demonstrate the significance of evolutionary variation in tendon and apodeme properties to realistic jumping contexts as well as the importance of considering the effect of muscle dynamics and behavioural constraints on energy storage in muscle–spring systems.

Keywords:biomechanics, elastic recoil, muscle, tendon
Subjects:C Biological Sciences > C340 Entomology
H Engineering > H140 Mechanics
C Biological Sciences > C100 Biology
Divisions:College of Science > School of Life Sciences
ID Code:34749
Deposited On:25 Feb 2019 15:39

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