Legal or illegal..LOL

Seriously, your best bet us to consume a protein shake both before and after heavy cardio days. It along with a good multivitamin or heavy doses of vitamin C will help prevent free radicals ( muscle damaging) from harming your cells

That and a meal with simple carbs as soon as your finished to help replace lost muscle glycogen

alright any recommendations for the protein shake

I would go with whey isolate during the day ( quick absorbtion rate) and something with casein in it before you go to sleep ( slow absorbtion)

Try and get in your bodyweight in grams for protein spread out evenly during the day, with an extra hit right after the intense cardio. I would even bring the shaker cup with you to the gym and have it IMMIDIATLY afterwards. The quicker the better for preserving your muscles..

Protein shakes all the way man. Just be careful with Whey It started to really give me stomach problems. I have been taking papayamine protein shakes its awesome and real easy on my stomach. Research it for your self its been working great for me.