There are 4 very real reasons you should be stretching:
Improves flexibility imbalances between sides.
I know what some of you are thinking, “Human beings aren’t perfect, so why bother?” Just because we aren’t perfect doesn’t mean we can’t strive to improve our current physical state. After all, we don’t get up in the morning and think, “Gee, my body isn’t perfect, so I don’t think I’m going to hit the gym today.“Just as we should be working to achieve a balance in strength from side-to-side, we should also be focusing to achieve balance in flexibility as well. Flexibility imbalances between sides will typically manifest into bigger problems down the line.
It decreases susceptibility to other injury.
The previous point leads right into this one. If you’re working to improve flexibility imbalances between sides, your body is going to work in a more optimal fashion once it re-learns proper movement and function.
Note: This does not mean your body is automatically going to be perfect; you’ve been moving the way you are now for quite some time. It’s going to take time and repetitions in your “new” body to really reap the benefits.
It improves length-tension relationship in muscles and improved firing of lengthened muscles.
Simply put, if a muscle isn’t at its ideal resting length, you’re not going to get ideal muscle function. The shortened muscle is going to cause postural distortions, and the antagonistic muscle group is going to suffer from poor motor recruitment due to reciprocal inhibition.
It improves quality of movement.
Something that I feel isn’t discussed frequently enough is the quality of movement. Quite often you’ll hear people refer to the ability of various forms of stretching to increase the ROM or the quantity of movement. When you take the previous factors into account (decreases in myogenic tone, decreased adhesion formation, improved flexibility levels between sides, etc.), you’ll find the quality of your movements will be greatly improved: smoother and more effortless.
To sum it all up, static stretching can promote balanced ROM from side-to-side, decrease susceptibility to injury, decrease the formation of muscular adhesions, improve firing of antagonistic muscle groups, and promote optimal function. Shame on you if you thought static stretching was stupid!