I have done the cleanse many times before. Sometimes I was able to go the gym & walk & cycle lightly. I tried lifting weights but I wasn't able to do my normal routine. Other times I had just enough energy to get through the workday, then come home & sleep (no workout).
I am on the cleanse now (Day 7) and this time I have been walking outside for my exercise.
I would judge by how strong you feel each day. I feel that somedays are easier to workout than others during the 10 days ...