Thanks again for your thoughtful comments.
So I guess if stretching within a normal range of motion is OK--our 'corporeal yawns'--then it's only the hamstring stretching I do that I may have to reconsider. And just to clarify: when I wrote it was 'almost painful' not to stretch out my hamstrings, I meant they tend to tighten up again if I don't stretch them (this was more of a problem when I was practicing karate every day for four to five hours). Perhaps it's trying to return to a more natural length. I don't practice karate anymore, so there's really no reason to be able to do high kicks (even if I were required to defend myself [unlikely in St. Paul], I'd just kick out a weight-bearing knee and run), except it still feels awesome to be able to put my foot up that high. In any case, you've given me a lot to think about, and I appreciate the suggestion to use a foam roller--I'll give that a try.
So I guess if stretching within a normal range of motion is OK--our 'corporeal yawns'--then it's only the hamstring stretching I do that I may have to reconsider. And just to clarify: when I wrote it was 'almost painful' not to stretch out my hamstrings, I meant they tend to tighten up again if I don't stretch them (this was more of a problem when I was practicing karate every day for four to five hours). Perhaps it's trying to return to a more natural length. I don't practice karate anymore, so there's really no reason to be able to do high kicks (even if I were required to defend myself [unlikely in St. Paul], I'd just kick out a weight-bearing knee and run), except it still feels awesome to be able to put my foot up that high. In any case, you've given me a lot to think about, and I appreciate the suggestion to use a foam roller--I'll give that a try.