[jumpinjeff]

Stretching done correctly is one of the best tools I have to improve dexterity and precision. Stretching done incorrectly can cause injury as you noted. Two words changed my methods from harmful to beneficial: Silly Putty. Treat those guitar muscles (fingers,hands,wrists,forearms,shoulders and neck) as if they were silly putty. Slow stretch and it will stretch safely for miles. Fast stretch and it will snaP. It is a matter of stretching for release and not stretching to feel the stretch.