Hi,carnt offer any advise,but have found this a very interesting thread as we have the same concerns with Benson who is also a four month old working cocker.we have found it just about imposable to keep him off the furniture and he is forever launching himself onto the sofa,off the sofa, onto the arm of the sofa and off again.He often uses the sofa as a launch pad to attack cloe 
and I'm sure hes eyeing up the baby gate which is very scary.
OH takes him for a fifteen minute on lead walk in the mourning,and I take him to the park or golf course ect for off lead walk late afternoon with the best intentions of limiting it to twenty minutes,but if i take a few photos or meet other dog walkers this will very often extend to thirty minutes or longer and i will come home feeling a bit guilty 
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However like you I struggle to see the difference between Benson romping around in the park,and him romping about in the garden or living room for that matter.Other than he does tend to do a lot more running in the park so perhaps this is the answer.
I don't know, which is why I'm asking. However, from asking a vet friend and looking around on the internet, I've found out the following...
My vet friend says the guidelines are general. She says some breeds (like Labs) have a very high incidence of hip, etc. problems, but she thinks it's unfair to restrict the exercise of all young dogs on these grounds. Although Cockers do get hip and knee problems, the breed information I have says it's not a major problem with the breed. My friends says puppies legs are damaged mainly by walking on hard surfaces (i.e. tarmac) and being forced to continue when they want to stop (e.g. by lead walking them or hiking/jogging with a pup). She says that it's a risk walking a puppy longer because it could have a genetic propensity to hip problems that would be exacerbated, but her mum's Sprollie was doing half-day hikes at four months old!
This isn't something I would want to do with Toq at four months, however!
Having checked the Kennel Club's website, the five-minute rule is a guideline aimed at all breeds. The guidelines even recommend not allowing a puppy to walk too much after eating because it might get bloat, which definitely doesn't apply to Cockers (!) After seeing a pug of Toq's age in the park, it does seem absurd applying the same guidelines to every puppy. The poor little pug puppy could barely walk. Toq kept jumping about wanting to play and the pug was hobbling slowly in circles
I can imagine that pug was exhausted after 10 minutes!
There are numerous posts by people owning high-energy, working breeds (e.g. collies, springers, etc.) with the same concerns we have. In summary, the puppy is under-exercised and tearing up the house, but they're scared to allow the puppy more exercise in case they damage its joints. Training and play doesn't exhaust the dog enough either because they're born to work (Toq drove me nuts before his vaccinations - he was practically doing doggie Open University. I spent hours thinking up new puzzles after he solved two Nina Ottosson ones on the first attempt).
My friend's recommendation was to avoid taking Toq on long 'walks', but instead to let Toq set the pace himself off-lead so he could decide when to stop. Keep Toq off tarmac as much as possible and allow Toq to run about on soft ground. Carry Toq or leave the area the minute he looks tired. Other recommendations I've read include not allowing him to play too long with other puppies because he'll get over-excited and carry on long past the point he's tired. In general, if Toq looks over-stimulated, I'll do some training or carry him so I can tell how tired he is. We also pick him up periodically so we can see how 'floppy' he is. If he relaxes in our arms after a couple of minutes and doesn't try to leap out, we carry him home.
Joint problems are close to my heart because, in August, I permanently damaged my knee doing the Great Glen Way with a 20kg rucksack. I now can't walk for more than an hour on tarmac without twinges, but I can walk up to four hours on soft ground. It was a real wake-up call for me and has made me pretty wary about injuring Toq.
Crucially, however, I knew I was doing damage but carried on anyway because I wanted to finish the route and was too proud to get a bag carrier. I was limping for two days before my knee eventually gave out seven miles from Inverness and I had to go to A&E. I may be wrong, but I suspect Toq would moan/slow and sit down long before his humans over-walked him. Again, this might be wrong (?), but I suspect the people over-walking pups are taking them on long country walks where the pup is tired/hurting, but doesn't want to be left behind. I was walked like that as a child so wouldn't inflict it on my puppy! My parents made few allowances for me being small.
But I'm going to try switching to walking Toq three times a day - 2 x 20 minutes on tarmac and one carrying Toq to the park and off-leading him for 30 minutes. At the moment, he's doing two walks - a short one (15 minutes on tarmac) and a longer one (20 minutes to and from park with 30 minutes free play in the park). Unsure about the doggie stroller - I think it will be unnecessary within weeks. It would also probably encourage us to over-walk Toq - we'd go out for a six-hour country walk pushing Toq in the stroller and, inevitably, Toq would want to come out all the time...
Oh, and a pink doggie stroller will make Toq look like he belongs to Paris Hilton and insult his machismo
To me, there's a fine balance to be judged between having Toq miserable and under-exercised, and storing up problems for the future. I don't think strict clock-watching is helping us draw that balance correctly right now, and wondered how others had managed it.
Thoughts please? Discuss...
