[Dabhand16]

OK - there are a few more things to think about here. Given the situation you will be in, it might be that the autofocus system of your camera may not funtion well, so you'll need the lens to be easy to focus - that is the focus ring has to be easy to access, some lenses have very thin focus rings, and they can be at the front or the rear of the lens. You need it where it feels best. You might be able to pre-focus a lot of the time, so it is not a huge problem.

Image stablisation would probably be an advantage. This will enable slower shutter speeds to be used, bearing in mind if you want to freeze any action, you will need higher speeds. So while for indoor/low light situations using a fair bit of zoom IS will let you get away with relatively slow lenses, the opposite applies to freeze the action. Here you have to have high shutter speed, and this requires fast lenses.

Don't forget you can increase the ISO to ease the problem, only you can decide if the increase in noise is acceptable. Sometimes noise can add to an image, and there are always noise reducing programs to fall back on too.

I doubt you will need more than 200mm at the top end unless the stadia you are going to be in are HUGE, but a 70-200 f2.8 lens will be quite heavy compared to a similar lens that is slower. A prime lens will be lighter. You could use a 70-200 with a monopod to make it less of an issue to hold for any length of time. Back to your choice again!

Can you get to a store to try a couple of lenses? you will know the sort of range you will be shooting at, so will probably be able to narrow the choice down to two or three that are suitable, then go for the one you find easiest to use.