If you've ever done some hard work - lifting, weight training etc, and felt ok for the first day or so, then started to feel muscle soreness, you've had DOMS.  This afternoon, it's my turn.  I generally don't get it, maybe that's because I don't train hard enough?  No way!  There's lots of explanations for it, the wikipedia article I've linked to above is a pretty good summary.  Generally I use a 4:1 carb:protein drink after hard training to reduce its effects.  According to Ed Bourke and Chris Carmichael's books this works, and generally my experience (placebo tested?  nope ... this isn't science on my part) is that it does.  C4P, or chocolate milk is my post-training drink of choice.  Whatever the cause and cure, today it's not working!  I didn't do the usual 50 lap enduro ride after my sprint training, which may have contributed, although that's contentious.  There's no proof that stretching or warmdowns reduce DOMS, but even if they don't, they're worth doing anyway if for nothing else than a bit of endurance work after strength training to keep some endurance up.

And for something simply amazing and completely unrelated on bikes, Artistic Cycling - have a look here.  It'll blow your mind.