A hunter pace is a form of competition involving horses and riders.
In a hunter pace a trail is marked for horse and rider to follow.
On the day of the competition, early in the morning, the hosts of the event send an experienced horse and rider to ride the trail as fast as it is safely possible to do so.
This morning ride is called "the dead body run", and it establishes two things: The pace time is the ideal time to safely but quickly ride the set trail.
Checkpoints set along the ride ensure that the riders are staying on course and are not overworking their horses.