5 Year olds - deadly, dangerous, determined

How many five year olds could you take if:

1. You are in an enclosed area, roughly the size of a basketball court. There are no foreign objects.
2. You are not allowed to touch a wall.
3. When you are knocked unconscious, you lose. When they are all knocked unconscious, they lose. Once a kid is knocked unconscious, that kid is "out."
4. Someone intent on seeing to it you fail gets to choose the kids from a pool that is twice the size of your magic number. The pool will be 50/50 in terms of gender and will have no discernable abnormalities in terms of demographics, other than they are all healthy Americans.
5. The kids receive one day of training from hand-to-hand combat experts who will train them specifically to team up to take down one adult. You will receive one hour of "counter-tactics" training.