Really really fast! Back when I was a sergeant at the local jail, before I made it to the patrol division, the K-9 handlers would let the trustee inmates volunteer to try to get away from the dogs. The guys would volunteer and they would put on padded suits for protection. They were then allowed to get a pretty lengthy head start before the dog was instructed to capture them. The K-9 always won that battle, not one time did I see a human outrun the dog, and some of these guys were pretty fast. It was pretty awesome to observe how smart the dogs were, they inevitably always went for the suspects arm and latched on before dragging them down to the ground. The K-9 would then hold the subject on the ground until an officer arrived to complete the simulated arrest. These dogs were also trained in tracking as well as drug searches. After observing several of these training sessions I can honestly tell you that there is no way I would try to outrun one of these dogs. My plan would consist of immediately throwing myself to the ground and hoping the officer got there quickly to rescue me.