Charyop---yes, I understand this, you're quite right. But there's another side. I found an interesting thread on an exercise-physiology board a few (i.e., many) years back suggesting that if you do a certain amount of weight training at the same time that you do your aerobic exercise---so do your interval sprints and then do a few heavy sets of some compound exercise---that you can `switch off' the routing of the call for calories that might otherwise target muscle protein. The idea is that the body will call for hypertrophy if it gets sufficiently overextended on weight training demands, regardless of the fact that you're also demanding compensation for calorie expenditure. So that only leaves any residual stored carbs (and of course the brain takes first dibs on these) and fat. I took these results seriously and tried it in the gym: I would do half an hour of hard intervals, followed by ten or fifteen minutes of serious leg presses or bench presses---big compound exercise, the idea was. And even though I'm pretty sure I went consistently into the red zone on my aerobic weights, I never lost any muscle tone at all---just got very cut. I'm restarted that program now, actually. So there's maybe more than one way to skin this particular cat. It's something to experiment with, anyway...
I really hate to monotor my heart rate, is what it comes down to...
So pick up the the method you like and try it out...BUT REMEMBER WE ARE NOT DOCTORS NOR WE DO WANT TO SUBSTITUTE YOUR DOCTOR!!!!! A VISIT WITH YOUR DOCTOR BEFORE ANY PHYSICAL ACTIVITY IS A MUST!!!!!
