Why four-legged animals are better sprinters – sciencedaily


Many four-legged mammals can achieve considerably faster running speeds than two-legged humans. Animals perfectly adapted to sprinting, such as cheetahs or antelopes, are characterized by a slender figure, long legs, and a particularly mobile spine to reach very high speeds when running. An interdisciplinary team including researchers from the Institute of Zoology at the University of Cologne has now developed a model that takes these characteristics into account and can calculate maximum running speeds for animals of any size. The results of their research were published in the article “Rules of nature’s Formula Run: Musclemechanics during late stance is the key to expliciting maximum running speed” in the Journal of Theoretical Biology.

The Tokyo Olympics are fast approaching and one of the highlights will be the men’s 100-meter sprint. The best sprinters can reach running speeds of almost 45 km / h. Sounds impressive, but it actually isn’t compared to sprint performance in the animal kingdom. It is only roughly equivalent to the top speed of a domestic cat. Cheetahs can run more than twice as fast (over 100 km / h), but other animals like antelopes (90 km / h), or even warthogs and hares (just under 60 km / h ) would overtake human sprinters.

The research team led by Dr Michael Günther (University of Stuttgart) studied the physical and biological factors on which the maximum speed of these animals depends. In the process, the researchers developed comprehensive answers to questions about the importance of body design, such as: “Why are maximum natural speeds achieved by medium-sized animals?”, “What characteristics? main factors determine the maximum running speed? ” and “What features set limits on speed?” ”

The heart of their theoretical work is the physical balance of the propulsive force of the legs and the resistance of the air to be overcome, as well as the inertia of the propellant muscles. They show a kind of main way to change the structural shape of animal bodies according to body size (allometry) by adapting to the fast locomotion driven by the legs. “This primary pathway describes how the shape of an organism must change with body size in order to achieve high running speed, and how specific shapes affect the maximum speed that can be achieved,” said Dr Tom Weihmann of the University of Cologne Institute of Zoology.

The classic example is the mouse and the elephant. An elephant-sized mouse would simply not be viable because its bones would break under their own weight. Elephants have much thicker and heavier bones for their weight as well as much longer and straighter legs. These characteristics make the enormous size of the animals possible. However, heavy bones and straight legs limit their top speed, which is much lower than that of cheetahs, even though elephants’ legs are much longer.

However, top speeds depend not only on size but also build, such as number of legs and spinal mobility. For example, many four-legged mammals are able to achieve much higher running speeds than bipedal models such as humans and birds because they can gallop using the muscles in their trunk for propulsion. “If the animals get too heavy, however, even stronger muscles won’t help, because bigger muscles take longer to contract at high speed. As a result, the weight limit above which sprint speeds begin to drop again is around 50 kg, which is quite close to the average weight of cheetahs and antelopes, the fastest sprinters on our planet ”, Weihmann explained.

The model can even be applied to fantastic creatures. For example, the giant Shelob spider from JRR Tolkien’s “Lord of the Rings” would be able to reach a top speed of around 60 km / h. In terms of the geometry of the human body, the model shows that the best sports sprinters are already very close to their optimal speed. Apart from technical applications like special running shoes or exoskeletons, providing elongation levers or extra elasticity, only longer legs or more elastic tendons would allow even higher speeds.

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Materials provided by University of Cologne. Note: Content can be changed for style and length.


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