Numbness increases flexibility?

I was sitting in a particular position such that my legs fell asleep. When they recovered just enough so I could stand but they were still numb and pins and needly, I got the idea that stretching my hamstrings might make the feeling come back quicker. To my surprise, I was able to lift each leg in turn very high, about 90 degrees! Normally they are so tight that they don’t go above 45 degrees without a lot of effort or patience. When the numbness eventually went away, they became tight again.

I’m wondering what causes this phenomenon. My friend theorized I was able to do this because there was no “stretching pain”. But usually when I stretch, just the tension itself is an obstacle long before pain is.

Now I was under the impression that the tension in our muscles was an actual physical property of the muscles - that developing flexibility was a matter of gradually changing the structure of the muscles. But this event makes it seem like flexibility is just a matter of nerve impulses and if you took a muscle relaxant or were say hypnotized, you could be super flexible immediately without any long term training. What’s the scoop?

This is basically the case for healthy individuals. Your lack of flexibility is due to your nervous system’s inhibiting the motions.