Have you ever looked around the gym and thought, “That person is definitely a runner”? There’s a certain look shared by many endurance athletes. They’re usually fit and lean, but there’s also something about their shoulders and the way they hold their arms. By the same token, you could probably pick out a football player by his thick neck and a ballerina by her impeccable posture—but why?
We could argue that some people are “just built for” their specific sport. And to some extent, this is true. “Morphology” is the term for general body shapes, and there are three main types: ectomorph, mesomorph and endomorph. We can see these different shapes show up more often in sports they are suited for. Long and lean ectomorphs tend to show up in marathons, mesomorphs dominate as muscle-packed gymnasts, and endomorphs represent as the powerful Olympic lifters and shot putters. But what morphology can’t explain is the physical changes that happen to people as a result of their sport.
The answer is almost hilariously simple: We are what we do. Or, to put it more scientifically, our bodies adapt to imposed demands. Ballerinas have such enviable posture—not because they were born with it but because they practice it over and over again. It makes you wonder whether they even know how to slouch.
But for a football player’s neck or a runner’s rounded shoulders, we need to look a little deeper. After all, you can’t practice your way to a big neck—it’s a structure thing. And runners don’t practice rounding their shoulders, it just starts happening. To understand why, we need to understand how our body adapts to the way we move.