Sports that take place indoors such as basketball, volleyball, and swimming are sometime hard to shoot – even with fast cameras and lenses.
Most indoor gymnasiums and pools are designed for the sport, not for the photographers shooting them. Here is a shot from a race in an outdoor pool. Even though most races and meets you can use flash photography as long as it’s not at the buzzer off the block (the swimmers watch for a flash that goes along with the buzzer to start) you just can’t get this kind of light indoors.
(Canon 60D, Tamron 70-200 f/2.8 lens)