Quote from JT47319:
My understanding is that it is more profitable to engage in cardio exercises AFTER engaging in weight training. Your muscles would be in a catabolic state, ergo they are cannibalizing themselves for the much needed protein. Lift weights, protein shake, then run.
I used to work out twice a day for 6 days, but I couldn't keep that up for more than 6 months. Otherwise, I think I'm in damn good shape. Could be better, but I'm more lean and mean like a male model than I am a weight lifter.