Why even the fastest person can’t run your cat


this weekend, The fastest sprinters on the planet gather together Tokyo Olympics Compete for the gold medal in the 100-meter sprint race. Lamont Marcel Jacobs crossed the finish line in 9.80 seconds, bringing Italy the first gold medal of the event. In the women’s competition, Jamaica won gold, silver and bronze medals-led by Elaine Thompson-Hera swept the opponent, she broke the 33-year-old Olympic women’s record with a time of 10.61 seconds.

But none of them can touch the legacy of Jamaica’s eight-time Olympic gold medalist Usain Bolt, who retired in 2017 but still has the title of fastest human being in the world. Bolt ran 100 meters in 9.58 seconds. The top speed is about 27 miles per hour, slightly lower than the top speed of a domestic cat. (Yes, house cat.) In the race against the world’s fastest animals, the cheetah and the pronghorn, Bolt has no chance.

You might think that how fast an animal can walk depends on the size of its muscles: the greater the strength, the faster the speed. Although this is true to a certain extent, an elephant will never run past a gazelle. So what determines the maximum speed?

Recently, a group of scientists led by Michael Günther, a biomechanist at the University of Stuttgart at the time, set out to determine the laws of nature that govern the animal kingdom’s maximum running speed.in a New research Posted last week in Journal of Theoretical Biology, They proposed a complex model that took into account factors such as size, leg length, muscle density, etc., to discover which body design elements are most important for optimizing speed.

This research provides insight into the biological evolution of legged animals and their corresponding gaits, which ecologists can use to understand how the speed limits of animal movement affect the population, habitat selection, and community dynamics of different species.For roboticists and biomedical engineers, knowing the body structure most suitable for speed in nature can further improve the design Biped walking machine and Prosthesis.

“It’s about understanding the reasons for evolution, and why and how it shapes the body,” Gunther said of the project’s goals. “If you ask this question mechanically, then you can really deepen your understanding of how evolutionary requirements shape car body design—for example, speed.”

Previous work in the fieldLed by Myriam Hirt of the German Comprehensive Biodiversity Research Center, it was discovered that the key to speed is related to the metabolism of animals. Metabolism is the process by which the body converts nutrients into fuel. A limited amount of nutrients are stored in muscle fibers for use when sprinting. Hirt’s team found that larger animals run out of this fuel faster than smaller animals because they need more time to accelerate their heavier bodies. This is called muscle fatigue.It explains why, in theory, humans can have Run past Tyrannosaurus.

But Günther and his colleagues are skeptical. “I think we might be able to give another explanation,” he said, which only uses the principles of classical physics to explain the speed limit. Therefore, they established a biomechanical model with more than 40 different parameters related to body design, running geometry, and the balance of competitiveness on the body.

The co-author of the study, Robert Rockenfeller, a mathematician at Koblenz-Landau University, said: “The basic idea is the two factors that limit the maximum speed.” The first is air resistance or drag. , When it tries to push the body forward, the reaction force acting on each leg. Since the influence of resistance does not increase with the increase in mass, it is the main factor in the capping speed of small animals. “According to air resistance, if you are infinitely heavy, you will run infinitely fast,” Rockenfeller said.

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