Flexibility & Performance
Flexibility is an important quality that must be trained daily. Flexibility is often a limiting factor inhibiting other qualities. Here are two references on stretching and warm-up that I have found informative:
Warm-Up and Stretching in the Prevention of Muscular Injury. Shrier, Ian. Sports Medicine. 38(10):879, October 1, 2008.
Some thoughts on flexibility, it’s place in warm-up and it's role in athletic performance.