CURRENT ARTICLE: Flexibility
that is a really good question to be asking, karky. the standard issue trainer paradigm is that you have to stretch to prevent injury. this is untrue.
first, you bring up a very good point by asking what good it does you other than being able to do the splits. exactly! if you don't need a certain rom, then being overly flexible is a liability. remember this little rule: you only want to be as flexible as you need to be. if you are more flexible than you need to be, you are vulnerable. the difference between your active and passive flexibility is your "flexibility deficit"... the greater the deficit, the better your chances for injury.
second, the whole idea that you can "prevent" an injury somehow by being more flexible is a misnomer. i prefer the term "injury minimization". in a perfect world, a well trained athlete under the perfect conditions can injure himself. that is the nature of living in 3d... chaos rules, and opportunities to injure ourselves are everywhere. by being unflexible or too flexible, you aren't guaranteed an injury either. it is not black and white. you are just vulnerable, and have more opportunities to hurt yourself, but you may still dodge that bullet for a while.
the best way to increase your flexibility is through active stretching, which means that you stretch using motion, preferably under a light load. this way you are only increasing the rom that you can control. passive flexibility is increased by static stretching, which only increases your tolerance to pain and also can deform the muscle fiber. this is done by pushing slightly beyond the level of comfort on a stretch and holding it for 30 seconds. another form of active stretching is isometric holds, which force you to actively contract a muscle in a stretched state.
incased within each muscle fiber is a tiny little string called a "spindle fiber". this little piece of important fiber is what determines how much the muscle and shorten or lenthen. if you want to increase the rom that you can control, you don't want to hold this in a stretched position, but you want to "re-educate" it by actively loading it in a gradually increasing rom. as alwyn cosgrove cscs says, "you only want your body to know that its going to be x range of motion, and it's going to be heavy."
the best method i have found to date is a complex given to me by strength coach, bill hartman. he calls it "rufus complex". start with a 45 lb bar, and do each exercise for 5 reps each, performing all of them back to back with no rest between exercises. this will serve a dual purpose, as it will jack up your nervous system, and get your heart rate up preparing you for the coming onslaught of heavy resistance. here are the exercises i would perform. some can be dropped if there is an injury, and you may want to add other exercises as well. basically you are just trying to get your body to prepare for a wide variety of movements.
hang clean (from thigh)
hang clean (from knee)
hang clean (from shin)
power snatch (may want to drop this one)
bent over row
that's 75 reps total. i think bill's version had more like 100, but this seems to cover everything i do in my training of myself and my clients. if there is some specialized area that i need to do an active stretch, i would suggest getting a foam roller and buy bill hartman's dvd. bill is one of the smartest fitness professional i have ever encountered (and i have met many, trust me). most of the best advice i ever give, i learned from him. although this video is marketed to the golf industry, it is not just for them. i use the exercises in that video in some form or another on all of my clients. you will also just gain a basic understanding of flexibility and how to attain it.
hope this was helpful.