what’s the protocol for this? empty or full stomach? supps important? etc.
I would always have some protein, with little to no carbs before (about an hour before), and then just some Whey powder post. I would always do my cardio on lower carb days, so if I was dragging a bit, it was to be expected. I believe CT’s approach in regard to the Anaconda protocol is to skip the finibars, but keep the Anaconda/Mag10 mix. This is what I plan to do for my next prep.
S
If you’re trying to lose fat, and it’s low-intensity cardio, you could do it fasted. It might help burn more fat slightly (it might not). Or you could have something beforehand, I don’t think evidence has been super conclusive about this.
If it’s high intensity or mega endurance, then you’ll want to consume something beforehand. Carbs, carbs + some protein, BCAAs, or a mini anaconda protocol are all ideas.
I picked up in the “Things I can’t prove but believe” thread in the T-Alpha cell to have fatty acids before cardio, it has worked well for me thus far (But I cannot put the credit on the fatty acids, as there are other variables 
I just use Power Drive before for fatty acids and Noops, then sip on my green tea for 30 min, then down a little bit more caffeine then head out, afterwards I have a shot of whey to hold me off as I make breakfast.
But that is all for low intensity, for High intensity, I would treat it like a weight training session, as everything is explosive in nature. Just less calories than one would with weights.
RM, this depends on what kind of cardio, when, and goals just like nutrition/supplementation for any other workout. Right now I’m in the process of bulking, I only do cardio on off days from lifting for overall health, because I am concerned of expending any muscle I may be gaining during this bulk I consume 40 grams of whey before my cardio, do a short 20 minute session, and then consume another 40 grams of whey with about 35-40 grams of higher glycemic carbs afterwards. This fits my goals for the time being. If you give us what your goals are and what kind of cardio your doing we could give you some more specific advice.