I shoot sport with canon 1ns and nikon f80 cameras, using the 540ez and sb26 flash guns. the cameras will give a set shutter speed usually 1/60 and a higher f-stop about f-11 or so.
this is ok if you want a large area of dept of field. but in my case the lower shutter speed it gives the subject time to move. ie for example you get a nice,sharp image on the film but a little bit of movement shows as very slight double image.which makes the photo useless for newspapers.
to fix this i have been using the Fuji NPH 800 iso film at a shutter speed of 1/125 the camera on manual and at a f-stop of f-5.6. i checked it first with my friends canon digital and it works great.good sharp action stopping photos.
if you have only 400 NPH drop the shutter speed to 1/90 and you will still get a great sharp photo.