You probably don't want to hear this but I agree with batgirl. Your body needs to digest whey protein and it's your digestive system that you need to rest... That said, I've managed to do light aerobic training on the MC, so why don't you start a bit of that? But lifting weights certainly sounds ambitious - I know I couldn't face it. You might consider just doing a 10 day MC, then going on to soups and juice for a few days and then veggies, fruit and other good things and this, with re-starting your training should get you back to fitness. Also, I've heard from others that you can continue the P&B shakes with veggies when you're off the fast and you will continue to cleanse. But I really don't think protein drinks will go with an Master-Cleanse - it might stop all the gunk coming out, which would be a pity after all the effort. For just 10 days, why not go for it? Just a suggestion but it's your decision in the end. All the best whatever you decide
Anya