i usually stretch b4 my workouts, not for a long time, but maybe load up the bar and while im standing there do a little stretching. my muscles tired usually so stretching helps a little bit..
even if you do a light set say warmup with 135 on bench or something, you are still kind of stretching in a sense. i just cant get in there throw on my heavy set and get at it.
i guess its still unknown, im always hurt though and i stretch so maybe i just shouldnt stretch and see how it goes...lol
later,
Todd