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.)
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