Can you elaborate here? This is a weird fascination of mine (man+canine).
I walk long distances with dogs, here's what I've found and ruminated:
1. If I chase or follow a dog, I can chase them to exhaustion.
2. If I'm walking several miles with a dog, they tend to trot ahead of me and stop and pant and wait for me. Rinse, wash, repeat. Bursted energy/rest cycles.
When we are in the field they will triple my distance travelled ( verified by GPS ). My outings are typically 8-12 miles and thus 24-36 miles for the dogs. Of course I need to keep them hydrated during this activity.
The behavior of running forward and looking back is most likely what we refer to as checking in. The dog is trying verify where you are heading/doing. In my dog's case they will range out to around 400 yards and then return to with 20 yards and run passed making eye contact as they run by.
Dogs (and the prey) can do burst sprints, but will easily overheat, and will need to stop periodically to cool down. Humans are furless and sweating is sufficient to regulate our internal temperature, so we can keep jogging for hours on end. Additionally, dogs are great at sniffing out hidden prey at the beginning of a hunt, and once found, humans are excellent trackers.