The small units that make up muscles are called sarcomeres.
Sarcomeres shorten when we contract our muscles. When we stretch for a long time, there is an increase in the number of sarcomeres. Literally, muscles get longer.
For example, increased flexibility is directly related to an increased number of sarcomeres. One of the ways that the number of sarcomeres can increase happens to all of us: Growth from birth to out 21st year. Growth in the length of bones during childhood provides a prolonged stretch of muscles. As muscles are stretched to their physiological limit they react by developing an increase number of sarcomeres. Stretch has to be of sufficient duration for this remodeling of muscle to occur.
The opposite is true as well. When muscles are left in shortened position, the number of sarcomeres decreases. Nothing provides a prolonged shortening of muscles like spasticity after stroke and brain injury.
So all the rules of stretching are thrown out the window when the muscle is spastic.
How is spastic muscle different than normal muscle? Let me count the ways...
Spastic muscles...
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| Help! Stretch me! |
For example, increased flexibility is directly related to an increased number of sarcomeres. One of the ways that the number of sarcomeres can increase happens to all of us: Growth from birth to out 21st year. Growth in the length of bones during childhood provides a prolonged stretch of muscles. As muscles are stretched to their physiological limit they react by developing an increase number of sarcomeres. Stretch has to be of sufficient duration for this remodeling of muscle to occur.
The opposite is true as well. When muscles are left in shortened position, the number of sarcomeres decreases. Nothing provides a prolonged shortening of muscles like spasticity after stroke and brain injury.
So all the rules of stretching are thrown out the window when the muscle is spastic.
How is spastic muscle different than normal muscle? Let me count the ways...
Spastic muscles...
•have lost some (if not all) communication with the brain.
•are often kept in a shortened position on the "bad" side for long periods of time.
•are not subject to the same rules of stretch. (That rule: The more you stretch the longer the muscle will become.)
Spasticity after brain injury keeps muscles (on the "bad" side) in a shortened position long enough to lose sarcomeres.
It comes as some surprise to most therapists, but there is very little scientific evidence that stretching muscle reduces spasticity. In the very short term there is a small reduction in spasticity. But spasticity is not reduced in any lasting way by stretching because spasticity is not caused by muscles. Spasticity is caused by brain injury. Brain injury causes the brain to cede muscular control to spinal reflexes. Increasing the number of sarcomeres will not reduce spasticity. If it did, every case of spasticity would be eliminated by a regimented stretching program. And wouldn't that be nice?
Soooooo... Should you not stretch? No! I mean yes! I'm confused! Yes, you should stretch!
Why should you stretch? Because even if stretch has no lasting effect on spastic muscle, there are several reasons to do it anyway. Stretch...
•feels good
•reduces spasticity for a sort amount of time
•is good for joints
•may be good for other tissue besides muscle (ligaments, veins/arteries, nerves, skin, etc.)
Spasticity after brain injury keeps muscles (on the "bad" side) in a shortened position long enough to lose sarcomeres.
It comes as some surprise to most therapists, but there is very little scientific evidence that stretching muscle reduces spasticity. In the very short term there is a small reduction in spasticity. But spasticity is not reduced in any lasting way by stretching because spasticity is not caused by muscles. Spasticity is caused by brain injury. Brain injury causes the brain to cede muscular control to spinal reflexes. Increasing the number of sarcomeres will not reduce spasticity. If it did, every case of spasticity would be eliminated by a regimented stretching program. And wouldn't that be nice?
Soooooo... Should you not stretch? No! I mean yes! I'm confused! Yes, you should stretch!
Why should you stretch? Because even if stretch has no lasting effect on spastic muscle, there are several reasons to do it anyway. Stretch...
•feels good
•reduces spasticity for a sort amount of time
•is good for joints
•may be good for other tissue besides muscle (ligaments, veins/arteries, nerves, skin, etc.)
5 comments:
I was told that stretching helps to momentarily relax the muscles so that then we can do the repetitive exercises needed to promote recovery. Does this make sense?
Hi Pete- 2 things:
1)I know you’ve talked about the difference between spasticity and contracture. But for me, it seems academic: all I know is that movement is effortful, slow (and often jerky.) But you have contracture, isn’t it essential to stretch, if as if you were recovering from a broken bone? Don’t most survivors in the “chronic” stage who have spasticity also have contracture?
2)I do yoga poses and pilates-type exercises, in addition to repetitive exercises (like walking). I feel yoga, especially, has helped me immensely ( I know, I have only have one data point). I wonder if stretching/yoga yields more results for someone (like me) who has more sensory/proprioception issues? Holding a pose seems to help me “remember” what my muscles used to feel like.
Grace: How are you!! Long time no see! To your comment....
1: I'm from the world of research- as you know. The research is clear: stretch effects neither spasticity or contracture or anything else that comes form spasticity. BTW, if your muscles are indeed contracted there is a small window of opportunity (basically before the muscle turns into connective tissue) that serial casting may elongate the muscle. But for the most part the only way around a contracture is surgery.
2: Yoga: Any movement is good movement in my book (literally, in my book!) and yoga because it makes the practitioner so aware of their movement is probably of great benefit. There are many benefits IN THE LIT that strongly suggest (we researches hate the word "prove") that yoga helps across many physiological and cognitive domains. All the best!
Mom: Yes, stretch "helps to momentarily relax the muscles." No doubt. But the next big volitional movement or associated reaction (from sneezing, getting up from a chair, etc.) and spasticity will come back. But as a precursor to repetitive practice, yes! Its just that, you may have to do it a lot because as you work hard the spasticity will come back. Thanks for the thoughtful comment.
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