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.

The myofascial network

The myofascial network is the three-dimensional matrix of soft tissues that work with our skeleton to give us shape. These soft but strong tissues include our muscles, blood, skin and connective tissues like tendons, ligaments and fascia. We all know the basics about muscles, blood and skin, but connective tissue is less well-known.

Everything in our body is surrounded by connective tissue of different shapes and textures. In some parts of our body, it is open like a spider’s web, and in other places, it forms sheets, layers and tube-like sheaths. This variety of structure gives fascia the ability to function in different ways. In our feet, it acts as a shock absorber, transferring the force of each step through our soft tissues to protect the joints of our knees and lower back.

Regardless of shape or location, fascia is mostly made up of collagen and water—lots of water. Did you ever hear that humans are 70 percent water? Our fascia holds most of that water for us. Like a wet sponge, fascia stretches, twists, compresses and springs back into shape.

When we walk or run, our fascia’s elasticity helps our muscles relax quickly so we can take our next step smoothly. It helps us bend into yoga postures and manage the odd positions we get into when we pick up our kids.

With every move we make, fascia adapts to help us do more with less effort. One of the main ways is through a process called mechanotransduction.

Structural response

Mechanotransduction is the method by which special cells in the body react to physical force by producing certain chemicals. In fascia, these cells are called fibroblasts. When stimulated, they produce collagen and other materials that reinforce the fascia by making it stronger or thicker.

Essentially, mechanotransduction is a structural response to forces, and it helps explain why runners get rounded shoulders. Running is all about forward motion. Not only do our legs propel us forward while we run, but our upper body also leans forward. If we run often enough, our connective tissue will pull us into the forward position—and voilà, rounded shoulders.

Fascia will adapt to any repetitive posture or movement. Office workers, for instance, can find themselves dealing with a tight lower back from too much sitting. The body builds up connective tissue in areas that support the sitting position, which makes it easier for the body to maintain but at the expense of mobility and comfort. It can even lead to chronic back pain.

In fact, many joint injuries are actually fascial injuries. Some, like tennis elbow or lower-back pain, happen from overuse and repetition. Others, like spraining an ankle during a soccer game, happen when our fascia isn’t fortified in enough places to withstand unexpected stresses.

To build a resilient, efficient body without compromising mobility or risking injury, we need to tweak our workouts with some fascia-boosting strategies.

Three ways to train for healthier connective tissue

1) Get more directions

Postures and movements that are too repetitive increase our risk of overuse injuries. If you only do one type of exercise—whether it’s running or Spin class or weight lifting— you’re at risk of overuse injuries. Fascia is remodeled along the lines (or directions) of stress. By moving in a variety of ways, we create stress in different vectors and generate tissue that is robust from any angle. Take a lunge, for example. We can lunge to the front, side, back or out on an angle.

2) Change up the speed

Fascia responds to rapid movement by improving its elastic ability to stretch and snap quickly back into shape. Slow and sustained movement, on the other hand, encourages plastic deformation of the fascia, in which the tissue starts to stretch into the position it’s held. This can increase our mobility by stretching out layers of fascia that are making us feel tight.

3) Load it differently

Most workouts already adjust load by increasing weight because we can lift more. But for fascia, we need to change the way we use weights, too. Consider the various tools we can use to add weight. Each tool has a different grip, center of mass and pattern of resistance. A dumbbell, medicine ball and kettlebell affect our bodies differently, even when they each weigh 45 pounds. Resistance bands, cable stacks, TRX and body-weight workouts also change how we use our bodies to resist force.

These three strategies are most powerful when combined. Moving in multiple directions with weight improves tensile strength—making our muscles and fascia long and strong. Moving loads at different speeds develops our elasticity. And slow, multidirectional movement allows our fascia to stretch out in three dimensions, increasing our mobility.

Photo credit: ramonespelt, Adobe Stock; Adam Gregor, Adobe Stock; KittisakJirasittichai, Adobe Stock; undrey, Adobe Stock