The Most Important Muscle in Your Body

Most of our days right now are spent rebuilding professional baseball players, preparing them for the most rotational sport on the planet. But yesterday, I got to talking with an NFL quarterback about the differences between quarterbacks and baseball players. It’s an interesting difference that we can all learn from because it shows there is little use for categorizing upper versus lower leg muscles. The reason is your core, more specifically your thoracolumbar fascia.

We previously introduced fascia as a layer of connective tissue that surrounds muscles, nerves, organs, basically permeating and extending uninterrupted throughout your entire body. We also discussed that this tissue is not just dormant plastic sandwich wrap, but has cells sensitive to pressure that allows communication throughout the entire body, similar to the control of the nervous system.

Perhaps most important is the thoracolumbar fascia, the deeper tissue of the back. It basically forms an “X”, starting right below the shoulder blades and running diagonally to your hip bone on the other side. In their 2007 research, Vleeming and Stoeckart discussed this fascia’s crucial role in transferring force between the spine, pelvis, and lower body. Remember we talked about your trunk being the internet connection? The healthier this tissue is, the faster and more effectively forces are transmitted when you run, throw, or jump. The authors go onto explain how this “glistening sheet of connective tissue, links two of the largest muscles of the body, the latissimus dorsi and gluteus maximus.”

How does this fascia relate? One of the main differences according to this NFL quarterback was the decreased importance of the front throwing leg. You can imagine you don’t want to have a wide stance like hitting a baseball or pitching, otherwise a 300 pound freight train can end your season (Tom Brady’s ACL injury). So that is where the thoracolumbar fascia plays a role. Force is still generated from the ground, through the back leg shin angle. But with a narrow stance of a quarterback, there is less ability to transfer forces to the front leg, and that fascia must be able to transfer and stiffen the front side by bracing the lead lat muscle for a strong, abrupt finish of the back hip and leg.

The answer is not just more pull-ups, the best upper body exercise and one of the chief means of improving lat strength. The answer is strength from many movements; pull-ups, rows, and yes even lower body strength movements like squat, because we know that no athletic movement targets just the lower or the upper body. Olympic weightlifters perform little traditional upper body work, but have extremely strong lats from holding heavy barbells on their shoulders. We also labeled fascia’s need to be “healthy”, not just strong, so releasing this fascia by lying on balls can help stretch and release fascia from the tightness of training. Another stretch, what we call “heel sit rotation”, shown below, can be a very effective, yet simple solution for mobility in this region.

So work on your “X”, you’ll need it to connect your lower and upper bodies, regardless of how you throw or what sport you play. Think of the thoracolumbar fascia as the fastest network, the most important one you’ll ever use.