I usually started my dogs as young pups working or exercising along with older dogs. There was never a need for anything. On an older dog who had not been conditioned we would work him along slowly until he was in condition. We found out by doing this by the time the dog was in condition to work or hunt his pad were tough enough. I don't really like to use anything unless it is very necessary. Even on hunting hounds, who sometimes will run for days if not caught, we don't use anything except conditioning. Some dogs were conditioned on treadmills if impossible to free run, which we enjoyed as much as the dogs.
I have seen dogs who had bare pads but was usually from being lost and running for days nonstop. Under normal working, hunting, running, sporting dogs we have never had a problem. Maybe some one else can give more info. I did know a man who exercised his dog on the pavement while riding a bicycle who had problems but he had other probles also and when he found another way to exercise his problem went away.