Here’s some helpful tips from Blacker on using your flash in actions shots to add a bit more of character!

Slow Sync Flash:
This will freeze your subject (because of the flash) and will render a nice background because your camera will be using a slower shutter speed thus causing some very creative backgrounds as well as some of those “wow” shots!

Try Panning During Exposure:
Combined with slow sync flash try panning along with your subject as they move by and you’ll capture some interesting effects with blurred backgrounds but an in focus main subject frozen by the flash.

Try Zooming During Exposure:
Similarly, try zooming your lens in or out during the exposure to get a sense of movement in the shot while still capturing it still during the flash.

Play around with of camera flash (if you can):
If you want to get really creative try some off camera flash techniques to light your subject as they travel by from different angles.