I have read that repeatedly overstretching a muscle will cause it to lengthen. The idea is that, as the muscle is stretched more and more, the muscle tissue increases the number of sarcomeres, which causes it to lengthen.
This can be seen more quantitatively in this diagram:
Caption: Serial sarcomere number versus time. The serial sarcomere number increases exponentially and converges toward a homeostatic equilibrium, which depends on the applied overstretch. Increasing or decreasing the overstretch, shown in blue and green, increases or decreases the serial sarcomere number. Modeled sarcomere numbers, shown as black dashed line, show the same trend as experimentally measured sarcomere numbers, shown as red circles.
However, I am having trouble finding information on the reverse process. Suppose a muscle is consistently shortened over time. How does this affect the muscle length?