http://www.bodybuildingforyou.com/articles-submit/tanja-gard...
For strength training, there’s evidence that stretching before a workout is counter-productive. Strength training requires muscles to contract tightly against a heavy weight, and loosening the muscle fibres by stretching them first reduces their ability to do this. This doesn’t mean you shouldn’t warm your muscles up before strength training – just avoid stretching them first. If you want to include stretching in the same workout as strength training, it’s better to wait until after you’ve finished your weights work.
I typically warm up on the elliptical machine for 5 minutes and then for each muscle group I'm doing that day I start with a set of low weight/high reps to warm it up. After the workout I do stretch my hamstrings because I sit on my ass all day.
Look at results from this search: http://www.google.com/search?q=dont+stretch+before+weightlif...
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"For strength training, there’s evidence that stretching before a workout is counter-productive. Strength training requires muscles to contract tightly against a heavy weight, and loosening the muscle fibres by stretching them first reduces their ability to do this. This doesn’t mean you shouldn’t warm your muscles up before strength training – just avoid stretching them first. If you want to include stretching in the same workout as strength training, it’s better to wait until after you’ve finished your weights work."
[Note: I did not refresh the page and see that user naner replied similarly. May I say: great minds think alike! Haha.]