If it is military training in junior high school and senior high school, tell the instructor that you are not feeling well, it must be physical reasons, otherwise it is not good to ask for leave.

If you say you are flat-footed, you can't take it out.

If you are a university military training, I suggest you not take time off.

Because military training in general colleges and universities is based on getting credits. If you don't take enough credits, you won't get a diploma.

In short, it is a bit difficult to ask for leave for military training, but it is not impossible. Saying you are not feeling well is the best excuse.