HIIT has its advantages but does jogging at a slower pace but constantly really burn more?
Zhadow said:I'll try and keep the physiology simple to be understood, But if anyone wants more technical biochemical explanation with the references, I can provide them.
During exercise your body is fairly efficient, and has been previously stated on this forum, you normally don't kick into burning fat until after the immediate energy storage in your muscles are used up Approx 20-30 minutes depending on your intensity and who you read. This is technically true. But there is a way to speed up this process.
There is an enzyme in your muscles called AMP Kinase (AMPK). The activity of this enzyme is increased when levels of Adenosine Mono Phosphate (AMP) are increased in your muscle. ATP is the energy for your muscles. When it releases its energy, it become ADP. During mild or moderate exercise, the majority of ADP is then reconverted to ATP. But during "strenous" exercise (e.g. 30 second as hard as you can sprint) your muscles need energy fast and so ADP is used for energy and converted to AMP. High levels of AMP stimulate many different activities in your muscle at levels that slow or moderate levels of exercise do not achieve. One of these is a very high stimulation of AMPK. (3 or more times the stimulation of moderate exercise).
The AMPK, by increasing the activity of some enzymes, and inhibiting others (e.g. Acetyl-CoA Decarboxylase, etc.) causes your muscle to start burning higher levels of fat (fatty acids) almost immediately. (based on animal AND human studies). In animals, chemically stimulating AMPK activity causes them to lose significant amounts of fat.
Think of it as when you exercise really hard for even a short period of time (30 seconds) increases the AMP in your muscles and your muscles think that means you are running out of energy and so they start the fat burning process much sooner than they normally would.
What does all this mean??? The post above counting calories, is simplistic and doesn't take into account the varying physiology.
If you want to do a slow jog, or walk or any aerobics, and want to burn more fat, for a given amount of time, then I recommend after a brief warm up, a 30 second sprint. then continue your exercise.
A better advice would be to do 30 seconds all out sprint, then 4 minute rest (walking) then 30 second sprint, and then continue your regular exercise. During which you will already be burning fat. (the 4 minute rest followed by 30 second sprint further increases the AMP in your muscles, causing higher stimulation of AMPK).
So you can see, even one high interval sprint, combined with your regular exercise can give you benefits that the regular exercise would take much longer to do.
Fascinating stuff.
Think of it as if high levels of AMP tell your muscle you are running out of energy, and so your muscle