Originally Posted by Aeroplane

Extra motion in the joints shouldn't be a problem unless it is not in the direction that it is intended to move, or else far more motion than it is used to. Flexibility increases your ability to use the muscle you already have, whether by increasing your stride length (running) or using different muscle groups (cycling).



"Intense" stretching is bad. If it hurts, you are going to far. And, if you stretch too far, the muscle can have a reflexive tendency to lose flexibility, making the stretch counter to its intent. I've been running competitively for 9 years, and that's one of the things that every coach who's worth his salt has told us.

Increasing flexibility and litheness are two reasons that American distance runners have been slowly getting more competitive on an international scale. In the 80's and 90's, the focus was on just working yourself to death, since it worked in the 70's. Stretching helps.