Track events are predictable; you know where the athletes are going to run. If you are at right angles to the track you can use panning to keep them sharp as they move across your field-of-view. If you get close to the track and aim your camera down the lanes as the athletes run towards you, a slower shutter speed is acceptable.
Football, rugby and other events played on a pitch are more difficult to cover because the action moves quickly around a large area. If you are close to a touchline, the players might be very close at one moment and in a far corner of the pitch a few seconds later. Use a faster shutter speed for close shots, as movement appears faster when nearby.
You don’t need to be at major sports events to shoot good pictures. Search out local games where the spectators stand on the touchlines and shout encouragement. The action can be just as strong and your viewpoints will be better.
Image stabilization is particularly useful when shooting with telephoto lenses as it reduces the effects of camera shake that are more noticeable when using longer focal lengths.
Canon’s Optical Image Stabilizer (IS) works by having a ‘floating’ element in the lens. Gyros in the system detect camera movement. This is analyzed by the onboard processor and instructions are sent which move the floating element up and down or from side to side. This keeps the image of the subject in one place on the sensor, even though the camera is moving. The system is so responsive that it can overcome the vibration of an engine if you are shooting from a car or helicopter.