Imagine you are an impala, racing across the African savannah to try and escape a cheetah – the world's fastest land animal, which can reach a running speed of more than 100 km/h (62 mph). It may seem like a hopeless effort, but in real life, impalas do sometimes manage to get away. Which running strategy do you think would give you the best chance of beating the cheetah?
A. Fast and in a straight line
B. Fast and zig-zag
C. Slow and in a straight line
D. Slow and zig-zaga
Agrowing body of research on wild cheetahs and their prey not only reveals the answer to this quiz – more on this below –by but also offers wider insights into why exactly cheetahs are so fast, and what we might learn from them to help our own athletic pursuits.
Alan Wilson, a professor of locomotor biomechanics at the Royal Veterinary College, University of London, UK, and his team have revealed a nuanced picture of cheetahs' athleticism. They have used special tracking collars to measure their speed and movements. They have also filmed the animals from an aircraft, and performed biopsies of the muscles of dead cheetahs. One crucial finding, according to Wilson, is that their athletic performance is about much more than speed.
"You look at a cheetah and think, 'there's an animal that's evolved to be the ultimate high-speed athlete'," he says. "But it's not, it's evolved to be the ultimate manoeuvrer, and it happens to be fast."
In a 2013 study published in Nature, Wilson and his team equipped three female and two male adult cheetahs in Botswana with tracking collars to gather data on 367 runs over 17 months. Until that study, data on cheetahs' speed was from captive animals chasing a lure in a straight line, or, for wild cheetahs, from direct observation and film, according to the paper.
The data from the collars did confirm that cheetahs are incredibly fast: the highest recorded speed was 93 km/h (58 mph, or 25.9 m/s). By comparison, the top speed reached by a human is 12.32 m/s, which was achieved by Usain Bolt in the 2009 Berlin World Championships in Athletics. There's no doubt, then, that if cheetahs were to compete at the Paris Games this year, they would win gold. But Wilson and his team discovered that there's much more to cheetah fitness than speed.
In fact, most of the tracked hunts involved only moderate speeds – but featured a lot of manoeuvring, such as speeding up, slowing down, and sharply turning. The cheetahs, which mostly hunted impalas, accelerated and decelerated with twice the power of polo horses, and accelerated faster than greyhounds at the start of a race, according to the study. Their anatomy plays a key part in these feats, with their powerful back musculature helping them accelerate, for example.
"Cheetahs are muscular," Wilson points out. "People look at cheetahs in a zoo and see a sort of two-dimensional coat rack, but a wild cheetah doesn't look like that. A wild cheetah has quite a bit of muscle on it. They're much more substantial than a greyhound. They've got big legs, big shoulders, lots of powerful muscles – that's an important part of being an athletic animal."
These strong muscles are supported by other useful anatomical features that allow them to move forward from the ground very quickly, as well as turning, he adds. "They have a lot of grip, they have these non-retractable claws, like a set of running spikes." He sums up how all these elements come together when a cheetah hunts: "The muscles work quickly and powerfully so you can speed up and slow down, the legs are strong so you can apply big forces and redirect, and the body is versatile… it can twist and you can lean into a turn". Even the tail helps: the cheetah whips it from one side to the other to bank the body over, using the tail as a counterweight in sharp turns.