What exactly happens to muscle? It simply stretches? Sarcomerogenesis? Both?

Hi, all. I've read a few different things and I'm a bit unsure of what actually happens to the stretched muscle in LL. I've heard that if it is overstretched, it looses its elasticity and your power/force production is never the same (I believe Dr. Donghoon Lee has the rubber band analogy). I've also read that the muscle responds to overstretch by generating new tissue, or sarcomere units.

Stretching Skeletal Muscle: Chronic Muscle Lengthening through Sarcomerogenesis
https://www.researchgate.net/publication/232226780_Stretching_Skeletal_Muscle_Chronic_Muscle_Lengthening_through_Sarcomerogenesis

Does some combination of both happen in real-world procedures? Do the 18%-20% lengthening limits keep things under some threshold where muscle ceases to be able to undergo sufficient sarcomerogenesis so that the muscle can settle into its new "operating regime"? Do some people develop soft tissue problems as a result of some mismatch of distraction rate and their individual physiology? (ex: maybe their bone consolidation is occurring too quickly, so faster distraction rate and their muscle cannot enough lay down enough new sarcomere units to keep up with the tension). Is the procedure some kind of balancing act between these things? Just trying to understand the interplay between stretching existing muscle, the formation of new muscle, and tightness/weakness in some patients after lengthening. Hopefully this question makes sense and thank you for letting me pick your brains on this. 

I am a very active person as an adult (30s), but my posterior chain is a bit shortened due to heels/lifts and no stretching or working out throughout high school and college. I've been working on these issues pretty diligently with a PT but uncertain how much more progress I can make, so pretty concerned about changes in tissue quality.

I think this is super interesting. I agree with this and other research I've found on this topic. More studies should definitely look into this

There appears to be both stretching and sarcomerogenesis, but the stretching can only go so far. My surgeon kind of addressed this when he was asked why his max for tibial lengthening is 6 cm.

Dr Parihar: The general experience, and my own experience has been that after 5 cms, people start having trouble with more pain, difficulty to exercise their muscles, and start developing deformities such as equinus (ballerina) and flexion of the knee. Muscles can stretch to a point (like a rubber band), but beyond that point they lose their elasticity (and become like a rope). Initially muscle stretch keeps pace with the increase in length of the bone, beyond 5 cms the muscles are not stretching enough to keep pace with the bone lengthening. They then pull on whatever bone/joint they are attached to and cause deformities which are very difficult to stretch out with physio, and require surgery.

http://www.limblengtheningforum.com/index.php?topic=2783.msg43784#msg43784

The tissue itself actuallu grows--it's not just the stretching of muscular tissue.

Quote from: KiloKAHN on December 12, 2021, 11:52:47 PM