If you're interested in reading more on ideas presented in the article below, I suggest reading Move Your DNA, Expanded Edition. If you'd like movement instruction via video, start with Daily Movement Multivitamin.
Body cast rhymes with podcasts, of which I've done about 50 in the last 8 months. On most podcasts I have been discussing this idea of how immobile we are--how it's not only that we exercise or don't. The very habitat in which we dwell is preventing full use of our body.
When I talk about "body casts" I use the analogy of a cast on a broken arm to illustrate a familiar example of how immobilization brings about tissue adaptations. For example, after wearing an arm cast for some time, you're likely to experience not only a decrease in muscle thickness, but a decrease in the length of your muscle as well. But it's not only loss. In muscles that are casted long, they have to adapt by increasing in length. Which in turn skews a joint's range of motion. And it's not only muscle tissue adapting. Connective tissue grows between muscles forming a sort of internal cast between unmoving parts.
Some casts (as in the case of shoes or a belt) are made of physically present "walls" that prevent a structure from moving through a full range of motion. In other cases a body is cast by a reflexive reaction to input. A good example of this is how the muscles in your eye will change shape in response to focusing on what's in front of it. A computer screen doesn't "hold" your eye lens in the way a cast holds an arm, but the reflexive behavior of the eye "holds the position" of your lens all the same.
While you, like me, may be attempting to optimize your physical body, there are things we do every day that take our structure away from well-being. We do these things because everyone did them before we got here and we assume their safety has been vetted, that the effects are well-understood. However, these items are loading our body--not for the better--almost all day long of almost every day of our lives. Meaning we are shaped much more by these cultural objects than we are to our favorite movement pastime.
Here is a list of items that cast parts of your body into a particular shape:
Computer screens (sets the shape of your eye's lens)
Briefs (The BALLS SHOW KatySays podcast will be released in February!)
Seats (Your office chair, favorite chair, couch...)
Baby devices (buckets, harnesses)
Repetitive use patterns
Flat and level ground
There are probably more, but this is what I came up with at the moment. As for flat and level ground, I find this cast to hugely impact the state of the entire body--and so I will spend the next few posts trying to explain why. Stay tuned.