aggressive chocolate lab

Question
We recently got a Chocolate Lab puppy... he was ten weeks old when we bought him and he is now nine months old.  Here is my problem:  although I am home with him and walk him as soon as we get up in the morning -- and it's a healthy walk of a few kilometers then a romp in the off leash park, sometime with other dog pals. Lately, he has been aggressive with me.  I can't tell if this is just 'play', but it has to stop.  He jumps up and bites at my coat sleeve and 'humps' me ... and sometimes we get into quite the battle with me putting him on the ground and telling him 'NO!'.  I find this VERY disturbing.  I LOVE this dog, and HATE it when our excellent walk is tarnished by this behavior.

'Edward' gets LOTS of exercise, LOTS of attention and training sessions, and has several of his own toys to play with -- his favorite being the soccer ball which we kick around in the park just behind the house.  

WHAT DO I DO TO STOP THIS?  HELP!  when he was a little puppy and would do this i would put him down on his back, but this just made him more aggressive so i took a different stance -- i would walk away and not 'play' anymore (this is what i was told to do in puppy training classes), but now that he is much bigger he is getting very hard for me to 'correct' in this way.

Edward is a VERY mellow dog by anyone's standard, and actually VERY well trained in every other regard except for this behavior which has become a daily occurance.  

In puppy training they told me to keep him away from other adult dogs or aggressive pups -- Edward is always quite submissive to them and gets the short end of the stick every time.  Is this what i should do?  it hardly seems appropriate to keep him away from playing with other dogs.  I do step in and 'protect' him when things get out of hand.  

Why is he doing this with me?  and what can i do about it?

Answer
Hello Mahara,

First is Edward neutered? If not, do so. He is engaging in this behavior because he is a dog. He is growing up and trying to determine who is the leader. Don't take it personally. It doesn't mean that he doesn't love you dearly.

Secondly, does Edward pull on the leash when you walk him? Does he reliably do a down command? This would be a barometer of how he views you. If he pulls or refuses to consistently obey the down command then he probably doesn't respect you. Make sure he does a proper heel and down command.

Finally, when he decides to challenge you with his nipping and humping, bite him on the neck. Forget about all the pseudo Alpha roll nonsense. Just bite him on the neck like his mom used to do when he was a pup. He'll understand that you're serious. You do this by purchasing a prong collar and attaching it to his neck with a leash. When little Ed starts his daily humping and biting, you give a quick sharp tug and say "NO".
Repeat with increasing force until he stops misbehaving.

That should do it.

Good Luck!

Sandy