Zombies, Run! 5K Training is a separate app from the main Zombies, Run! app, and doesn't contain any Zombie Chases. Chases are included in the main app as a way to create a very basic kind of Interval Training, however as Zombies, Run! 5k Training is specifically an Interval Training app we have not included randomised chases in this version.
The 5k Training app was intended to be a more structured series of workouts to help people gain running experience, rather than the free form running used in the main Zombies, Run! app. We wanted to make sure that each app could be used separately from each other, so it’s for this reason the 5k Training app does not have this feature.