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Footpads manage increasing body mass: mammals


Dog's paw / HTO / LicensePD - Public Domain

The footpads of mammals maintain functional integrity as body mass increases through changes in geometry and material properties.

"In most mammals, footpads are what first strike ground with each stride. Their mechanical properties therefore inevitably affect functioning of the legs; yet interspecific studies of the scaling of locomotor mechanics have all but neglected the feet and their soft tissues. Here we determine how contact area and stiffness of footpads in digitigrade carnivorans scale with body mass in order to show how footpads’ mechanical properties and size covary to maintain their functional integrity. As body mass increases across several orders of magnitude, we find the following: (i) foot contact area does not keep pace with increasing body mass; therefore pressure increases, placing footpad tissue of larger animals potentially at greater risk of damage; (ii) but stiffness of the pads also increases, so the tissues of larger animals must experience less strain; and (iii) total energy stored in hindpads increases slightly more than that in the forepads, allowing additional elastic energy to be returned for greater propulsive efficiency. Moreover, pad stiffness appears to be tuned across the size range to maintain loading regimes in the limbs that are favourable for long-bone remodelling. Thus, the structural properties of footpads, unlike other biological support-structures, scale interspecifically through changes in both geometry and material properties, rather than geometric proportions alone, and do so with consequences for both maintenance and operation of other components of the locomotor system" (Chi & Roth 2010)
About the inspiring organism

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Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Improved cushioning for footwear, tires, construction equipment, prosthetics, with better spreading of load. Using cushioning to provide energy in moving devices.

Industrial Sector(s) interested in this strategy: Engineering

Biology Department
V. Louise Roth
Duke University
Chi KJ; Roth VL. 2010. Scaling and mechanics of carnivoran footpads reveal the principles of footpad design. J R Soc Interface.
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Bates KL. 2010. The bigger the animal, the stiffer the 'shoes'. Duke University Office of News & Communications [Internet],
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