my point is, can a human reasonably stay within viewing distance from a dog that is running away from him? the dog can just run at top speed, gain some distance, take a little rest and maintain that distance at a comfortable pace.

I used to believe in the endurance hunting thing until I realized playing with my dog it didn't make sense. They DO get tired, but they take a 1 minute break and it's like they are back square 0.

For the record, I'm in shape and with a pretty light frame (181cm/70kg) and go for 10km/1 hour jogs regularly.