Hamstring cramping and tightness problem. Stretching questions.

[Bouncer]

I read not to stretch before or during a workout, just to proper warmups. The theory was stretching tears the muscle fibers and you dont want to do that as it weakens you for your lifts. You should stretch after the workout, bonus is the muscles are already warm. I always heard you were supposed to stretch for longer, like a minute at a time?

If I dont stretch before a workout I cant get through a workout. My hams get to tight. I have noticed no weakness.