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Elastic mechanisms are very important in the movement of vertebrate animals. The muscles that control vertebrate locomotion are affiliated with tissues that are springy, such as tendons, which lie within the muscles and connective tissue. A spring can be a mechanism for different actions involved in hopping, running, walking, and serve in other diverse functions such as metabolic energy conservation, attenuation of muscle power production, and amplification of muscle power production.〔Roberts, Thomas J., and Emanuel Azizi. "Flexible Mechanisms: The Diverse Roles of Biological Springs in Vertebrae Movement." The Journal of Experimental Biology (2011): 353-61. Print. 8.〕 When a body is running, walking or hopping, it uses springs as a way to store energy which indicates that elastic mechanisms have a great influence on its dynamics.〔Lan, Chai-Chieh, Kok-Meng Lee, and Jian-Hao Liou. 2009. Dynamics of highly elastic mechanisms using the generalized multiple shooting method: Simulations and experiments. Mechanism and Machine Theory. Pg.2165-2178〕 When a force is applied to a spring it bends and stores energy in the form of elastic strain energy and when it recoils after the force has been released, this energy is released as well.〔 Elastic proteins provide the property of elasticity which gives the spring the ability to bend reversibly without the loss of energy, and the ability to bend to large strains with small force.〔Gosline, John et al. 2002. Elastic proteins: biological roles and mechanical properties. Philosophical Transactions: Biological Sciences, 357:121-132 4.〕 Elastic proteins also contain high resilience and low stiffness which helps with the function of elastic strain energy. While running, tendons are able to reduce the metabolic rate of muscle activity by reducing the volume of the muscle that is active to produce force. The timing of muscle activation is very important for utilizing the mechanical and energetic benefits of tendon elasticity.〔Sawicki, Gregory S., Emanuel Azizi, Thomas J. Roberts. 2008. Timing of Muscle Activation for a “Tuned” Muscle-Tendon Elastic Mechanism. National Science Foundation.〕 Power attenuation by the use of the tendons can allow the muscle-tendon system the ability to absorb energy at a rate beyond the muscles maximum capacity to absorb energy. Power amplification mechanisms are able to work because the spring and muscles contain different intrinsic limits of power. Muscles in a skeletal system can be limited in their maximum power production. Power amplification by the use of the tendons allows the muscle to produce power beyond the muscle’s capacity.〔 The mechanical functions of tendons contain a structural basis and are not subjected to limitation of power production. == Elastic Mechanisms for Metabolic Energy Conservation == From previous experimental studies on large animals, it was noted that during active locomotion mammals save much of the energy they would otherwise need for running by means of elastic structures in their legs. Measurements been made of the rates of oxygen consumption of various animals, as they walked, ran or hopped, revealed that at high speeds animals seem to save more than a half the metabolic energy they would otherwise need for locomotion.〔McNeil, R. A. (1984). Elastic energy stores in running vertebrates. American Zoology , (24), 85-94.〕 A notable example is jumping in kangaroos. When hopping at slow speeds, their uses of energy increase linearly, but at high speeds, kangaroos can move as cheaply (from an energetic perspective) as if they were moving at slower speeds.〔Irschick DJ, Henningsen J. 2009. Functional morphology: Muscles, elastic mechanisms, and animal Performance. P. 27-37 In Princeton Ecology Guide. Ed. Simon Levin. Princeton University Press. Princeton, New Jersey. Pdf〕 Deep research in to the anatomy of large mammals such as, kangaroos and other large ungulates such as deer and gazelle, suggests strongly that some sort of elastic mechanism is important for this energetic savings.〔 Previous combination of careful experiments, with anatomical (e.g. tendon dimensions), mechanical (e.g. force plate recordings) and mathematical calculations revealed that a significant fraction of the work done with each step could be provided by the spring-like action of tendons, rather than by muscle work.〔 When the animal’s foot contacts the surface of the ground during high speed locomotion, the tendon or ligament is pressed tightly together, storing elastic energy much like a compressed spring. As the foot gets of the ground, the pressure on the compressed tendons and ligaments is released, and elastic recoil from these spring like structures provides additional force to propel the animal thus resulting in energetic savings.〔 Simple calculations based kangaroo hopping and forces involved in hopping show how storage of elastic strain energy can save twenty to thirty percent of metabolic energy required for hopping. Measurements of oxygen consumption with fluctuations of kinetic and gravitational potential energy, indicate elastic savings of at least fifty four percent at high speeds.〔 It is important to take under consideration that metabolic benefits of elastic structures are probably most apparent for larger animals, rather than small organisms such as insects. This results from a simple fact, that larger animals can exert much higher forces on their tendons and ligaments during movement, compared to small animals.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Elastic mechanisms in animals」の詳細全文を読む スポンサード リンク
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