Reasons to throw out static stretching before exercise-prior to exercise this type of stretching can inhibit blood flow, cause muscles to relax too much, and go as far as putting micro-tears in muscle prior to exercise… all bad…
Uhm…static stretching pre workout has been contraindicated for years. Dynamic motion stretching as a warmup is good stuff, provided there is some progression (Example: In my classes, I have the students start doing front kicks at knee level and progressing to head height.)
Static stretching after a workout helps to keep the muscles from tightening and most especially keeps the connective tissue more elongated, enabling an increasing ROM.
10 minutes after a workout won’t cut it if you are looking to increase flexibility, 20-30 minutes daily at a minimum. As far as athletic performance itself, the jury is still out, I recommend it heartily for injury prevention. My ankles are flexible enough that I can stand on the edges of my feet with the soles touching each other. This has saved me from rolling my ankle innumerable times running. Also, if you happen to go down on the bike and your leg gets caught/slides out, the more flexible you are, the further you can go before the muscle fibers and connective tissue start to tear.
And, finally, with swimming, the more flexible you are the better your reach/catch will be. High flexibility allows you to stretch and reach, getting a “fuller”, longer pull, and a more efficient stroke. Ankle flexibility allows the foot to relax out in an extended position, as opposed to having to use the calf muscles to point it.
Little things like that. Being flexible may not directly affect performance, but the net effect of being flexible will produce dividends.
John