Training Grounds are areas in Mirror's Edge used by Runners for warming up, practice, and to train new Runners in the art of Parkour. There are only two shown in the game: the new training grounds used by Faith Connors during the Tutorial Level Training Area, and the old training grounds seen at the end of Chapter 2, Jacknife (chapter). Whether there are more in the City of Glass is unknown.
Old Training GroundsEdit
The Old Training Grounds shown in Chapter 2 are considerably smaller than the New Training Grounds, although it is placed rather discretely, with buildings encompassing the area, meaning that City Protection Force would not locate the area very easily. There is an above-ground subway line a block away from the area.
The reason for its abandonment is unknown. It is unlikely that it was discovered, because if it had been it would have probably been stripped of all platforms and challenges set up by the Runners. Before the events of Mirror's Edge, Blues generally ignored the presence of Runners in the city, so would not bother locating it anyway. A more likely idea is that it was outdated. The new Training Grounds are considerably larger, and feature many more challenges than its predecessor; zip lines, crash pads, and horizontal pipes to balance across. Another reason may be because it was ageing and falling apart, as shown by the wooden ramp Jacknife runs across in Chapter 2 falling off the building as he jumps, and the pole he grabs to recover collapses during mid-swing. The wooden additions to the area are also quite creaky while the player stands on them, possibly due to being weak, but this noise can also be heard on many other wooden additions throughout the levels, so this may not have been a factor.