My feeling is this: set the camera's ISO level to 500,640,or 800 as the STARTING POINT for the majority of action shooting when using "consumer" cameras and consumer zoom lenses. More-modern cameras, made within the last 4 years, are pretty decent at 800 to 1,250 ISO. As the light levels drop in the afternoon, it is quite often necessary to elevate the ISO to 1,600...ESPECIALLY if your camera has a slowish lens, like say a 70-300 f/4~5.6 or the newer f/4.5~5.6 lens.
Second thing--as most consumer zooms are zoomed out, the max aperture lets in less light, down to as little at f/5.6 or even f/6.3....so, keeping the lens at the shorter end, or perhaps in the middle of the zoom range on lenses like the 80-400 Nikon or 100-400 Canon, will keep the aperture at f/5 or f/5.3.
It is better to have a slight bit of noise and a crisp, stop-motion image, than a low-noise, ISO 200 shot with smeared motion.
One tried and true method for better action shots is to get a "fast" lens, like a 50mm f/1.8 or 85/1.8. A lens with a wide, light-gathering aperture value of f/1.8 to f/2 will allow for fast shutter speeds. At ranges of 30 to 100 feet, there is PLENTY of depth of field to allow use of the lens at f/1.8 or f/2.