I thought I'd give you a couple of examples showing some sporting events taken with slower speeds.
This was taken at 1/500s - less than 1/2 the speed you used.
Canon 30D - Canon 70-300mm - 1/500s f/5.0 at 200.0mm iso400
This one was taken without a flash I did bump the ISO and set the aperture wide open.
Canon 30D - Sigma 50-150mm - 1/200s f/2.8 at 54.0mm iso500
Not exactly a sporting event, but running was involved and this was taken on a very cloudy afternoon. 1/250s was fast enough to stop the action.
Canon 30D - Canon 100-400mm - 1/250s f/4.5 at 105.0mm iso400
I thought maybe the examples would help more than the explanations.