Biology
The Biomechanics of High-Speed Locomotion in Cheetahs and Greyhounds
Quick fact
Cheetahs and greyhounds both reach speeds over 70 km/h (45 mph) using a 'double suspension gallop' in which all four feet leave the ground twice per stride. This gait relies on a flexible spine that acts like a spring, storing and releasing elastic energy to lengthen each stride and increase speed.
Why this is interesting
Cheetahs are famously the fastest land animals, but did you know that greyhounds—dogs bred for racing—use almost identical body mechanics? How do two such different animals achieve such similar top speeds?
Read the full explanation
Understanding The Biomechanics of High-Speed Locomotion in Cheetahs and Greyhounds
Imagine two athletes, one a sleek cat and the other a slender dog, both built for one thing: speed. They look different, but their bodies have converged on the same solution. The key is their spine. Instead of being a rigid rod, the spine of a cheetah and a greyhound is highly flexible. When they run, their back flexes and extends dramatically, like a bow being drawn and released. This allows their powerful hind legs to reach far forward and then thrust powerfully backward, increasing the distance covered in each stride. But that's not all—their limbs are long and light, with muscles concentrated near the body to reduce inertia. Their paws are also specialized: cheetahs have semi-retractable claws that grip the ground like running spikes, while greyhounds have a deep chest and streamlined shape to reduce air resistance. Together, these features allow them to achieve incredibly long strides and rapid stride frequencies, propelling them to speeds that are unmatched by most other land animals.
A deeper explanation
The secret to the high-speed performance of cheetahs and greyhounds lies in their ability to store and release elastic energy. When a limb hits the ground, the muscles and tendons—especially the Achilles tendon—stretch, storing energy like a spring. This energy is then released as the limb pushes off, providing much of the force needed for the next stride. This elastic recoil is more efficient than using muscle contraction alone because it essentially 'recycles' energy that would otherwise be lost as heat. Furthermore, the flexible spine acts as a second spring: during the gallop, the back flexes and extends, storing and returning energy that contributes to the forward propulsion. This system is so effective that cheetahs and greyhounds achieve a 'double suspension' gallop—meaning there are two moments in each stride when all four feet are off the ground. This maximizes the time spent airborne, allowing them to cover more distance. Ultimately, these biomechanical adaptations—flexible spine, long limbs, and elastic tendons—are what allow these animals to sprint at astonishing speeds. Understanding this not only reveals the elegance of evolutionary design but also informs engineering and sports science, where similar principles are used to design prosthetics and athletic footwear.