I checked some of the photos I took last year using my Nikon D3S and the Nikon 70-200mm f2/8 VR II - I always use a monopod so the VR II feature was turned off.
Shooting at f2.8 under crappy stadium lights, I was shooting a f2.8 with a shutter speed of 1/1000 or 1/1250 - depending on which end of the field I was shooting - ISO was 8000.
On a field with really good lights I could drop the ISO down to 6400 while keeping the aperture at f2.8 and the shutter speed 1/1000 or 1/1250.
If we extrapolate and use a lens that has a minimum aperture of f5.6 (2 full stops slower than f2.8)so to get the same exposure as above you would need an ISO of 8000x2x2 or an ISO of 32,000 (which should generate a lot of noise) or you could drop the shutter speed down to 1/250 and not be able to stop the action -- or -- you could shoot at ISO 16,000 at 1/500 - still get a lot of noise but should be able, with good technique, be able to stop most of the action.
This assumes you shoot at the max aperture of your lens but unfortunately most consumer zoom lenses need to be stopped down at least a full-stop to get sharper images - shooting at f8 now means an ISO of 64,000
And remember, with the VR feature enabled your focusing speed is slowed down - noticeably.
