personally I scale things WAAAYY back during the MC. I generally commute to work by bicycle (45 minutes each way) + workout on a pretty intense resistance program 5 days a week. When I do the Master-Cleanse
I stick to yoga and walking. What I've found is that without the carb intake necessary to fuel the muscles, I "bonk" or burn out way too quickly. Too much of this consecutively can be harmful.
Fellow cyclists have found the same situation when doing the Master-Cleanse
and trying to keep their regular regimen in place.
I've read where others have done their workouts without problems, I really don't know how unless they have some reserves to work off of.
But everyone is different.
There you have it, my two cents....