A common question posed of me is, "Should I warm up my muscles by running, skipping rope, etc., before I stretch? Won't I pull a muscle if I don't warm up? I read In Wikipedia you should always warm up before you stretch, and that must be right (:0). You stretch COLD?" Yes, I do. And always have.
I have found through personal experience that if you stretch when you are cold, you will see how tight you really are. If you warm up first, your muscles fill with blood, and it is easier to stretch. There is no argument to that. You will probably stretch farther and get deeper into your postures when you are already sweating. However, if you can get your muscles to lengthen without "warming" them up, your gains in stretch will be more permanent. Your flexibility will not be dependent upon breaking a sweat first.
When you stretch when you are "cold", it takes longer to stretch. It will probably hurt more, but not necessarily. The "hurt" is the cold muscle struggling to lengthen. If you go slowly, as I STRONGLY suggest, the hurt goes away. You must be patient. Do not bounce, or throw yourself into the position. The action of stretching will warm you up anyway, so the stretches you work on later in your routine will come easier than the first ones. You still won't be as warm as if you skipped rope or ran around the block, but the end of your routine will be easier than the beginning.
My reason for doing the stretching cold was practical. I grew up in New York, in a rough neighborhood, and the winters were cold. If someone wanted to start a fight with me, I could not say, "Excuse me, before you try to kick my ass, I have to stretch first." I needed my body ready, regardless of the weather, time of day, my level of fatigue, to be able to use my martial arts skill to defend myself.
In other things in life, I need my body ready without having to prepare first. But it takes time and effort to get it that way.
Tomorrow: Part TWO, the great cold stretch experiment!