AK should typically be raising/reraising in a tourny setting as is the original question. Zach explained it very well so this will be redudent mostly but the reason AK is so good is that it will win a lot of pots on the and does very well against calling ranges. As zach pointed out use stove, it is a pretty solid favorite vs AQ+ 88+.
Typically in tournys, people have pretty small stacks and as it gets later in the tounry blinds/antes make up a significant portion of total stack sizes and stealing becomes very important. So later in the tourny not only can you steal the blinds by raising, but you make be able to also steal the person trying to steal, and even if they call you are really usually crushing their range(lets say average stack is 15BB) since people will start stealing wide and have to call down lighter than say the first orbit. And as zach showed, even using a conservative range AK still is in great shape.
Overall, the real beauty of AK is its fold equity as hands such as 55,66 shouldnt be calling(since those hands against our range are bad) and even if called we are usually either dominated them or in a coinflip. While AA and KK are obviously in villians range, its not a big part as we have one of each already which significantly decreases those chances.
