Escape velocity is just around 5 m/2 so don't pitch it too fast or it won't come back! Even a Little League pitcher should be able to throw a ball at 20 m/s or so.
Most healthy adults should be able to do that, especially with a running start. It's about as much as you need to do to get a passing grade in PE at age 16 in most places. Also in this hypothetical you don't have to fight much gravity while accelerating - only inertia.
(Except, as others have said, I wouldn't have the traction to accelerate.)