> one tentatively draws evidence from studies of children and exercise
We allow our toddlers to play to get thier excersie, we don't force them to walk the pavements or fields, most toddlers would refuse to walk very far and kick up a tantrum untill back in the buggy!!, but most pups wouldn't notice thier bodies feeling tired at the time of a walk making it easy to over walk them past thier personal limits.
> Some of them contradict each other slightly and most of them promote the need for exercise
Forced excersie (ie lead walking/treadmill) and free excersie (allowed to run & play in a safe area) are different things.
> Also (and of course I am not a dog!) I have joint problems and have been advised by professionals such as osteopaths, physiotherapists, chiropractors and surgeons to do exercises to strengthen the muscles around the joints for extra support. Would this be similar in dogs?
Yes, same for dogs.
Buster was diagnosed as a pup with elbow displasia (he was crippled with it, courld barely walk :( ). A short, slow daily lead walk was prescribed for the very reasons you have said, but it was VERY short, only about 10 yards to start with (couldn't manage any more), this was built up over time very slowly. It was a carefull juggling act between getting the speed & distance right, too fast and he'd pay for it after, too far and he' pay for it. I couldn't allow him to walk at the pace he wanted to start with, I had to slow him down.
Now as an adult (4 & half years old) the pace of his walk rarely effects him and to my suprise he has even recently ran his entire route
(gets with his rottie buddy and he turns into an energetic dog!)
with no ill effects :) Lots of energetic play-bows can still give him a bit of a limp though :(