Hawttiekins is absolutely correct. If you are going to teach them not to jump on people at the dog park, they should not be allowed to jump on anyone else at any time. Dogs can't deduce the differences between at home and somewhere else, or between family and friends. They are either allowed to jump or they aren't.
Kneeing them is not only not effective, it's just plain mean. Dogs respond to body language, and the worst thing you can do to a dog is ignore them. In their own language, if their pack alpha is displeased with them, he will turn his back on them and totally ignore them, sending the message that what they are doing is not good.
If they jump on you, fold your arms in front of you and turn your back to them, saying NOTHING to them. Don't LOOK at them. Give them absolutely no attention until they get down, then turn around and talk to them. If they jump up again, fold your arms and turn away from them until they have all four feet on the floor. Eventually they will get the message that you will not deal with them if they jump on you.
Jaybay is our resident training maven, I am sure that when she gets here she'll have a couple of great suggestions for you! :)
Ghilly
the best way to teach a dog not to do that is to not let them do that at home,,for instance when they jump on other people,you family guest say in a ferm voice no ,,beause if you tell them its ok at home they think its ok anywhere.that just confuses their little heads..so dont let them do it at home and im sure that will help.
I had a similar problem and I felt the same, thinking it was cruel to knee my dog in the chest. When I tried it out I got him in the head a couple of times. But eventually it worked. Still he likes to jump but now it is in front of me and not on me. Good luck.
i hate when dogs jump on me, so i do not allow my dog to jump i startedher right off if she jumps she get introuble, when mine jumps and they learning i pop them in nose they not jump no more. no fun being jumped on with your dog but to have someone elsa dog do it is a pain, i will not go to a few friends houses because they let there dogs jump on you and they big dogs , so i just stay away from them.