In today's world, our thoracic spines get no love. Here is a lateral view of the spine so that you can see what area I am referencing:
The thoracic spine is our mid-back onto which our rib cages attach. It is prone towards loss of motion due to our sedentary, desk-bound lives. In addition to our time spent slouched forward at our desks banging away at our keyboards, we have thrown in our hand-held devices. Now, when we're commuting home from work, we're reinforcing that forward head, forward shoulder posture often seen when sitting. Over the course of time, the thoracic spine can get stiff and kyphotic (rounded forward). I call it going back into the technological womb. In utero, we are flexed. Then, as we develop through our motor milestones, we gain the ability to extend. Modern life is undoing all that hard work we did as babies and toddlers.
So, why does thoracic spine mobility matter? As mentioned, our rib cages are attached to the t-spine. Good mobility in our thoracic spines will help make breathing easier. Pretty important, right?
Another reason that it's important to maintain good t-spine mobility is to optimize healthy shoulder movement. Our shoulders are ball-and-socket joints. Think of a golf ball on a tee. Optimal health of that glenohumeral (GH) joint and the rotator cuff (four muscles that control how that golf ball rotates on that tee) relies on proper mechanics of the scapula (shoulder blade) as it relates to the rib cage on which it sits. I tell my patients that their scapulothoracic joints must be mobile yet stable platforms from which to "launch" their ball-and-socket GH motions (flexion/extension, abduction, internal rotation, external rotation, horizontal abduction/adduction). The scapulothoracic joint is the "core" of the shoulder. If one cannot move the thoracic spine well, then the scapula will have trouble getting into the ideal positions necessary to maintain healthy GH joints.
Try this experiment to see what I'm talking about. Stand up and stand tall. Now, raise your right or left (healthy) arm up overhead as far as possible. See how far you can raise it by watching yourself in a mirror. Next, take your arm and reach behind your back as you attempt to touch your opposite shoulder blade. Ideally you'll be able to reach far enough to at least touch the inferior angle with your finger tips. Now, try slouching forward at your mid-back and repeat those same two movements. Was it more challenging? Did you get as far? Probably not. This is an example of how a stiff, kyphotic thoracic spine can negatively impact shoulder movement.
Another reason one should want to maintain thoracic spine mobility is so that your lumber (lower) spine won't have to overwork. When your body begins to lose mobility in an area where it ought to otherwise have it, then it will simply seek that mobility elsewhere in the kinetic chain. Your bodies are great at compensating in order to get you from A to B. It will sacrifice form for function. However, while it's impossible to declare, "Because you move this way, injury X is bound to happen," it is safe to say that optimizing healthy movement patterns will help reduce your risk of injury.
For you folks out there who are desk bound, who have low back pain, or who are having trouble with your shoulders, please consider addressing your thoracic spine. It is a big player in a lot of musculoskeletal pain and dysfunction.
Here are two quick and easy drills you can do to help keep your thoracic spines healthy:
Give them a try, and use them in good health.