Hi, there are differing views regarding whether a person should exercise during a fast or not. Allan Cott had has patients walk for three hours daily. I believe Shelton had them lie in bed all day. Others hold that the lymphatic system needs to be kept moving and so exercise is not only a good idea, but it is actually necessary. I would encourage you to read the various ideas behind both the theories for exercising, and the theories against exercising, and then make a decision for yourself.
My longest fast so far has been four days. I have fasted about one day a week (sometimes two days) for the last year or so. From my own experience, little as that experience may be, would be if you are wanting to keep up the exercise, you may or may not have the energy to do so even if you want to. Everyone is different and you may become exhausted from exercising and you may not. It is always good to read the various reasons for both sides of the issue though.