It's a combination of shooting skills and a timed event. You run to a station (arrows must be in the quiver) and take your best shot, then you run to the next station and shoot. In all I think there were five targets. Then you run back. Your score is a combination of what you shoot and how fast you can do it.
The older guys usually make better shots, but the young bucks who can really run fast can still win it if they have on their running shoes.
Its a fun event. You run so fast its hard to conertrate on the last shot with breathing heavy and all.
The IATBS is an amazing event with lots of fun shoots. My wife and I look forward to it every year. My advice is to try everything once, thats why its fun. If you loose an arrow they make more everyday.