With 800 speed film, the optimum F-Stop is f 4 or f 2.8. The aperture setting must be considered along with shutter speed. Shutter speed describes how quickly the shutter opens and closes exposing the film to a flash of light. The higher the shutter speed the shorter the exposure. High shutter speed is the primary tool for stopping action.
Direction of movement is also important.
For fencing, this would mean positioning the camera at either end of the strip near the reel. An example of this would be the view of the referee. However, the greater the shutter speed the more light is needed, and again for fencing there is usually not much. Also, if you use any type of telephoto, a 250 or above shutter speed is needed to avoid camera shake which can blur your photo. Pratice this article.