If you can, pre-focus on a point where the action happens. I shoot women's barrel racing and pre-focus on the 2nd/left barrel and get the shot as they come around. Then, using back-button focus, I can then get them coming off the 3rd/back barrel on their run for home...using continuous/AF-C focus and the back button, it allows me to track the rider. When done, I go back to the barrel, hit the back button to focus on it, then wait for the next rider.
In track, say the broad jump, you could focus on the take-off pad and catch the shot as they come off. Or the pole vault, focus on the middle of the cross-bar and get them as they approach/clear it. (this is essentially what we do when photographing equine jumping shows, too).