Monday, October 10, 2016

Stuff I Learned - Week #5

I'm pretty enthusiastic about active stretching. While there may be a time and a place for passive stretching, I've found that active stretching tends to possess three oft-desirable attributes:
  • The gains in flexibility come quicker.
  • The flexibility gains tend to be longer-lasting.
  • The flexibility gains tend to be greater.
In addition to these positive benefits in flexibility gains with active stretching, I've also found that active stretching tends to better support joint stability. And as many of you know, I'm very interested in techniques that facilitate greater stability of both body and mind!

OK - so what is active stretching? Active stretching is where the yogi or yogini contracts the muscle that's being stretched. For example, in Supta Padangusthasana (Hand to Foot Pose), the hamstring is contracting at the same time that it's being lengthened. I think many of us (most of us?) have a sense of what contracting means, though what are the mechanisms that underly contraction?

Muscle contraction begins with an intention, which via complex mechanisms in the nervous system results in an electrical stimulus (action potential) at the muscle. This action potential then catalyzes a release of calcium (see previous blog about calcium storage in the bones), which begins the process of muscular contraction.

Muscle contraction happens at the cellular level, in an interaction between the proteins actin and myosin. Actin and myosin get along OK, as long as there's some energy put into their relationship. When that energy (ATP) is invested into their relationship, some cool movements occur!

At this cellular level, we see that the filaments of these proteins slide one across each other. In this video, we see some of the various mechanisms that underly this sliding action, and how the summation of many, many sliding filaments contributes to muscular contraction.

Perhaps you're thinking, my muscles contract, so why should I both trying to figure out what the diagram to the right means? Or why would I want to digest the video's discussion of actin, myosin, ATP, etc? Good questions!

If you're in a hurry, I think the primary take-aways from today's blog are these two points:

  • Muscles can only shorten to a certain extent. At that maximum shortening, the actin/myosin fibers are jammed up, and cannot shorten any more.
  • Muscles can only lengthen to a certain extent. That's right, muscles do not really stretch (unless they're being torn). Beyond a certain limit, the actin/myosin are no longer connected to each other, and then the muscle fiber is no longer able to function.
The latter point serves to debunk a lot of the focus of MPY (modern, postural yoga) on flexibility, and also shows us the potential power of this practice. Stretching, and any resultant flexibility, is more about training/conditioning the nervous system than it is about making muscles longer. Trying to lengthen muscles (independent of teasing apart fascial adhesions) is not the greatest use of anyone's time.

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