I wouldn't recommend it as I heard it can cause problems even if you are careful.
But I'm a hypocrite as I used to double bind in full binders at a physically demanding and humid job. Luckily, I didn't have trouble in those few years. I also learned how to breathe small short breaths when I was a kid in order to hide panic attacks, so I breathe like that while binding.
If you have to wear a binder, I would go with what FTMDiaries said and see what causes you to pant/be careful. I would also vote on attempting to control breathing and staying hydrated (8 cups of water a day hydrated).
As for the locker room, I don't know as I didn't start binding until after high school. While gross (sweaty), it's not fun/took a good couple of minutes to take binders off or put them on. If you choose to wear a binder, you could either wear it all day or switch between two (one for gym, one for school). There are also tri top binders and swim binders that would potentially work better/be less restrictive and easier to change.
Good luck and stay safe.