As a rule, every editor I've worked for HATES these types of photographs, so if you have dreams of being a newspaper photojournalist and don't want to spend quality time in your bosses office getting your butt chewed out, I advise you to not follow my example.
That said, when I can, and very judiciously, I like to show the motion that athletes are in while competeing in their sport. To do this, I use a slow shutter speed of 1/8th to 1/15th of a second focused on my subject while at the same time moving my camera at the same speed of the subject as I press the shutter botton on the camera. The effect is that the subject is in focus because it is moving at the relative same speed as my moving camera and the background is blurred.
The photograph shows in a still photograph the motion of the athlete. It takes some practice to get the timing down and rarely do I make these kinds of photographs on the first try, but with practice and repetition it's not a hard photograph to make with the right subject.
First, watch how your subect is moving and practice following that movement through your lens, then set your camera so that you are shooting at the mentioned 1/8th to a 1/15th of a second. If you're photographing in bright sunlight, a neutral density filter along with setting your camera to its lowest ASA setting will get you to the lower shutter speed.
Now try it for real making exposures. Experiment with slower and faster shutter speeds and different subjects moving in different ways until you find what works for you. In these days of digital there is no film to waste, so make a lot of photographs and check the backscreen of your camera for proper exposure and to see if you are getting the effect you want. Yes, I do that also.
Have fun with it and make a photograph that is different and exciting...Well, that's what I do the day before I end up in a bosses office trying to explain myself.....
See ya on the sidelines,