I am not quite sure how that would work if you worked on a project alone and need to review a large stack of code or you work with somebody else, you can't exactly take 3 minutes on a threadmill.
If you work on a team, mark time on your calendar where you are busy and stick to it - there are very few emergencies that really are more important than maintaining your own personal productivity - in the rare event that you hit one, throw an exception.
And that may sound self-centered and harsh, but really, your most valuable time at work is your time in flow. If your employer doesn't value that, and feels free to interrupt you willy nilly as well as drop you into the middle of a 1960s boiler room of coders happily jabbering away instead of writing code, your project and likely your company is doomed.
If you're working alone and you're blocked, go exercise, it works like magic because it monkey wrenches your brain out of the infinite loop that's keeping you from seeing the solution. If you aren't blocked, go exercise anyway. Make it a regular habit.
Finally, review that stack of code after you come back from the gym. You'll be in a much more receptive state to do so.
