Motion blur halp

[dyyylan]

I shot some pictures of my friends last weekend, and since the sun was so bright (and apparently 102° at one point) I figured I'd just use my flashes to fill in some shadows, depending on the spot...

However, I'm using the nikon CLS to trigger flashes off camera, which limits me to 1/200. Since the flash isn't what's stopping the motion, just adding some light, im getting motion blur. In this shot it's not a huge deal I guess but I'd like to know how I can control it better in the future.

If I have to do this I usually just use a sb600 on the hotshoe with auto FP so I can shoot at like 1/500 or 1/750 and still get some extra light... but that doesn't help me much hah, are there any other options?

Here's one of the images: