Track Stars and Floppy Necklaces: What's the Deal?

So on Saturday night, in Birmingham, England, the American Galen Rupp ran 5000 meters in 13 minutes 11.44 seconds. (I went out to dinner with my wife and had warm chocolate cake for dessert, so I had a pretty awesome Saturday night too. But I digress.)
In case you're wondering, Rupp's 13:11.44 is a new American record for 5000 meters. He snatched the mark away from Bernard Lagat by 6/100th of a second.
Let that sink in for a moment.
Good? Now, to put things in perspective: That "moment" you just took probably lasted 100/100th of a second! Maybe more!
The point is, Rupp notched this new record — over 5000 meters, mind you — by a margin so slim, "razor thin" seems inadequate to describe it. If I were Bernard Lagat, right about now I'd be thinking one thing and one thing only:
"Dang. Maybe I should ditch the necklace."
That's right. Like many elite runners — track types especially, it seems — Lagat is a serial necklace-wearer. As shown here:
2010 Reebok Boston Indoor Games
Sometimes he puts it in his mouth, like this:
2008 Olympic Games Beijing, China    August 8-24, 2008 Photo: Ji
I've always found this mouth thing sort of quirky and endearing, but the track-star-with-floppy-necklace phenomenon in general has always puzzled me.
I mean, seriously: When events — especially sprints — are routinely won and lost by hundredths of a second, wouldn't you maybe want to leave the dangling gold chains and stuff at home on race day? In the aforementioned 5000 meter scenario, isn't it plausible that something like a flapping necklace could add 6/100th of a second to your time? That it could seem less like jewelry around your neck, and more like an albatross?
For the record, I am in no way picking on Mr. Lagat. I am and always have been a fan of his. And in any case, as I've said, this is a widespread thing. Here are just a few photos I was able to dig up quickly…
Floppy necklace, headband, watch, wristband. You have to know the team that designed Michael Rodgers' skin-tight suit saw this and shook their heads:
2009 World Outdoor Championships
Necklace and double wristbands? At least it's symmetrical:
2010 Rieti World Challenge
Usain Bolt isn't wearing a necklace, but the guy behind him is. Just sayin':
2008 Olympic Games Beijing, China    August 8-24, 2008 Photo: Ji
Asafa Powell, wearing not only a necklace but a Livestrong wristband and a watch. I guess in case he wants to check his splits every 25 meters or something:
2007 World Athletics Final Stuttgart, Germany   September 22-23,
Sanya Richards is a necklace wearer…
2009 World Outdoor Championships
…but then, she also has one of THESE necklaces.
2009 World Outdoor Championships
So I guess she's earned the right to wear pretty much whatever she wants.
me? I like my wedding band...