I have decided to do these "lectures" because I am tired of bodybuilders screwing up their training and then don't understand why they don't gain. I first explained why and how you should split your training
http://www.getbig.com/boards/index.php?topic=390663.0, and now I will explain how you should perform aerobics to maximize fat loss.
I have seen dudes performing aerobics too fast in the belief that doing it faster burns more calories, and I have seeen dudes barely walking on the belief that slower aerobics maximizes fat burning. Both are wrong.
Yep, when you run/pedal faster, you do burn more calories for the same amount of time performing an aerobic exercise, but you burn more glycogen than fat. Why? Because fats have to be first broken down and taken to the liver to be convered into ketones by a process called glycogenolosis. This is a slow process. If your run/pedal too fast, there is no time for the body to perform this, so it will resort to the muscles' stored glycogen to get the energy it needs. If you perform aerobics even faster, like if your sprint, there is no time for the body to use even glycogen, so it will use adenosine triphosphate instead. If you walk, you'll always burn fat, but if you walk too slow the amount of fat burned will be very small. The ideal for maximum fat burning is too perform the exercise with an intensity that will be at the very upper rang of using fat as energy right on the edge of where the body starts using glycogen.
So, as you can see, whether the body uses fat, glycogen or ATP to move depends on how fast you move it. Beneath 65% maximum intensity(walking to fast walking), the body uses fat, between 65% to 90%(running) or so it uses glycogen, and above 90% effort it uses adenosine triphosphate, which can be released as energy immediately.
To maximize fat burning, find what your 100% maximum sprinting speed and heart rate is, then try to walk at 65% of that speed for as long as you can. At first, you will only be able to handle this for 40 minutes, but eventually you should be able to handle up to two hours. Doing more than two hours of aerobics even at this low intensity increases glucocorticoid levels, so it is not adviced...
SUCKMYMUSCLE