As a general rule, everything on this planet is adapted to do what they do best. Beavers have giant teeth that continue to grow throughout their entire lives so that they can chomp down trees. Owls have giant, brilliant eyes adapted to spotting scurrying food on the ground and scaring the shit out of unsuspecting campers. And honey badgers don’t give a shit.
But what about adaptations within a single species? Michael Phelps was born to swim thanks to his ginormous hands and disproportionately long torso. Shaquille O’Neal was ridiculously quick for his enormous size, giving him every advantage on the baseline.
However, special adaptations seem to be able to apply to an entire class of people, as evidenced by a recent study from Penn State. In it, associate professor of kinesiology Stephen Piazza shows that sprinters have a bone structure in their ankles and feet specifically designed for speed.
Piazza took eight sprinters – defined as currently in competition and training for at least three years – along with eight non-sprinters, and took a look at their ankle and foot bone structure with an MRI scan. After making some measurements and crunching the numbers, he found that sprinters have a longer forefoot (from toes to that ball on your ankle that juts out) and a shorter heel (from the Achilles tendon to that same ball). He then created a simple computer program that confirmed why this is helpful.
“Imagine a wheelbarrow with 30-foot handles. Such long handles would provide you with great mechanical advantage compared to what you would get from a wheelbarrow with three-foot handles, but rapidly producing the same rotation of this wheelbarrow would be more difficult because you’d have to move the ends of the handles really fast. It is easier for your hands to generate these lifting forces when they move a few inches rather than a few feet in the same amount of time,” said Piazza. “The Achilles tendons are like your hands; they are better able to lift your body (the wheelbarrow) when the handles are long enough to provide sufficient leverage without being so long that they prevent rapid force generation by the calf muscles.”
Of course, there are many other variables that make a good sprinter, like percentage of fast-twitch muscles to slow-twitch muscles, stride length, stamina, practice and much more. Also, this is an instance of correlation, not necessarily causation. What I mean is, it could be that having this bone structure allows people to be better sprinters. But it could also be that practicing sprinting so much has caused their foot to slowly take this shape over time.
It’s a classic example of the chicken and the egg.