The key is that the PACK starts off first and get a head start. Th JAMMERS (one per team, wearing a white helmet) take off and try and break through the PACK and then upon lapping the PACK on the second time around they get a point for each one they pass. It's the job of the PACK to make it as difficult to get by as possible without using their arms legs or elbows, ie: hips and shoulders only.
You have to see it live with the crowd going berzerk to get the real feel for the action, despite the magnificence of my photos at conveying the mood of the event. It's like hockey in that aspect and a few others actually (they both skate for one). | 
Dr. Naysay
What are the rules? 
