Shrinkage is a sign of healthy hair with great elasticity. Think about a slinky. When you release a slinky its job is to pop back into starting position unless you continue to stretch the slinky out. At that point if you release the slinky it will continue to be limp and will not spring back into place.
So, the next time we complain about shrinkage let's all be glad our hair is giving us a sign of being healthy.