by Steve Holman, Iron Man Magazine
Q: When is it best to do cardio? I’ve tried first thing in the morning before breakfast, but I felt tired and burned out by midmorning, and my job suffered. Is right after a weight-training workout good? If so, for how many minutes?
A: I recently interviewed top researchers, Gabriel Wilson, M.S., and Jacob Wilson, Ph.D., and they believe that doing cardio first thing in the morning on an empty stomach is highly catabolic. In other words, it wastes away your hard-earned muscle tissue. That makes sense considering you’ve been fasting for eight hours or more while you slept and your body is in the early stages of starvation.
That means your body will burn way too much muscle in order to preserve fat because it perceives famine. It also means lots of fatigue—as you found out. Therefore doing cardio first thing in the morning on an empty stomach might not be a bodybuilder’s best choice.
The optimal time, according to the Wilson brothers, is right after a weight-training workout. I suggest about 20 minutes of medium-intensity work on a treadmill after your last set of weights.
After a workout is when you’ve burned off all the sugar in your bloodstream. Your body will go to bodyfat immediately for the energy it needs during medium-intensity cardio. Go at a pace that’s hard enough to elevate your breathing but not so hard that you can’t carry on a coherent conversation.