Gapping the field refers to having a very intense and strong last hundred meter dash in a middle distance or long distance race. This term can only be used when someone is clearly picking up pace when coming down the last 200 meter or less during a race.
"Damn Chase and Noah are gapping the field in that 800 meterrace."
Mainly used in sport for fitness or running. It basically means to skip corners while running around a field or track for fitness or just for a warm-up lap.