The Academy of Sport entrance doesn't cause you to cross private land, since, as I understand it, the academy of sport is on public land.

It does, however, as the 10 million signs will inform you, require you to be a criminal trespasser.Technically, a security guard could, should you fail to give him your name, detain you there.

That said, noone seems to mind.

If you are intent on being a rebellious outlaw, at least be discreet.
IE.
- park in the main carpark, not at the trail head
- drive very slowly
- give way to pedestrians
- don't play music really loud