Nature: Four-legged animals can run much faster than humans because they can gallop

Why Usain Bolt will NEVER be as fast as a cheetah: Four-legged animals can reach much faster speeds than humans because they can gallop and use their trunk muscles for propulsion, study finds

  • Experts from the universities of Cologne and Stuttgart have modeled running speeds
  • They include factors such as body shape, number of legs and propulsion power
  • From this they can calculate the maximum walking speed of a certain animal
  • World-class sprinters, they found, are approaching our theoretical maximum speed

Animals that run on four legs can reach much faster speeds than humans because they can gallop — using their trunk muscles for propulsion — a study has found.

Researchers led by the universities of Cologne and Stuttgart developed a model for the maximum possible walking speed of a creature based on body structure.

When applied to humans, the team found that world-class sprinters — such as those currently competing in the Olympics — are close to our maximum potential speed.

At the height of physical fitness, people can reach running speeds of nearly 45 kilometers per hour – about the same as a domestic cat.

Cheetahs, on the other hand, can run more than twice as fast, reaching a speed of about 100 kilometers per hour.

Animals that run on four legs can reach much faster speeds than humans because they can gallop — using their trunk muscles for propulsion — a study has found. Pictured: a cheetah

The study was conducted by animal physiologist Tom Weihmann of the University of Cologne and his colleagues.

After assessing the physical and biological factors that determine animals’ top speed, the team created a biophysical model for running — the core of which is the balance between a creature’s propulsive leg power, air resistance and muscle inertia.

It also takes into account physiological characteristics such as body shape, leg length, number of legs and stiffness of the spine – all of which can influence the animal’s maximum speed.

Based on this model, the team identified a “main path” showing how the structure of animal bodies must change with body size to reach optimal speed.

“This master pathway describes how an organism’s shape must change as a function of body size to achieve high walking speed,” says Dr. Weihmann.

In addition, he added, it describes “how specific shapes affect the maximum speed that can be achieved.”

Elephants' heavy bones and straight legs (pictured) limit their top speed, which is why elephants are slower than cheetahs, even though they have longer legs, the team explained.

Elephants’ heavy bones and straight legs (pictured) limit their top speed, which is why elephants are slower than cheetahs, even though they have longer legs, the team explained.

As an example, the researchers point to the contrasting body plans of elephants and mice. Relatively speaking, the former have thicker and heavier bones and longer and straighter legs, all of which are necessary to achieve such large sizes.

(In contrast, a mouse scaled up to the size of an elephant would be too delicate — its bones would eventually break under its own weight.)

However, elephants’ heavy bones and straight legs inherently limit their top speed, which is why elephants are slower than cheetahs, even though they have longer legs.

“However, if the animals become overweight, even more powerful muscles will not help, because larger muscles take longer to contract at top speed,” said Dr. Weihmann.

“Correspondingly, the weight limit above which sprint speeds start to decrease again is around 50 kg [110 lbs], which is pretty close to the average weight of cheetahs and pronghorns, the fastest sprinters on our planet,” he explained.

When the team applied their model to the design of our bodies, they found that the top sprinters in the sport are already getting very close to the maximum speed that humans can theoretically achieve.  Pictured: Usain Bolt, the world's fastest man, sprinting at the 2016 Olympics

When the team applied their model to the design of our bodies, they found that the top sprinters in the sport are already getting very close to the maximum speed that humans can theoretically achieve. Pictured: Usain Bolt, the world’s fastest man, sprinting at the 2016 Olympics

When the team applied their model to the design of our bodies, they found that the top sprinters in the sport are already getting very close to the maximum speed that humans can theoretically achieve.

In addition to adding technical improvements such as special running shoes or body-strengthening exoskeletons, just developing longer legs or more elastic tendons would allow human sprinters to reach higher speeds, the team explained.

The team whimsically noted that their model can even be applied to fictional creatures. For example, Shelob – the giant spider from JRR Tolkien’s “The Lord of the Rings” – could reach a top speed of about 60 mph if it were real.

The full findings of the study have been published in the Journal of theoretical biology.

HOW CAN THE CHEETAH’S INNER EAR MAKE IT FASTER?

The inset shows the cheetah's inner ear, which affects the animal's balance

The inset shows the cheetah’s inner ear, which affects the animal’s balance

Scientists have discovered one of the keys to the incredible speeds of the world’s fastest animal, the cheetah.

The balance system, in the inner ears of vertebrates, consists of three ducts that are semicircular.

The ducts contain sensory hair cells and fluid.

The cells detect head movements.

Each of the three channels has a different angle.

They are all particularly sensitive to different movements: one is sensitive to up-and-down movements, the other to sideways movements, and the latter to tilt movements that go from side to side.

New research from the American Museum of Natural History has found that two of the three semicircular canals in the inner ear of the modern cheetah are different in length than those of extinct species.

Scientists believe that the design of the animal’s inner ear has evolved over time to make it faster.

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