This has tickled my brain for a while so I finally decided to post it up here. Give it a look-over and tell me what you think.
I don’t feel like being wordy so I’ll go point form:
When we do “cardio” we generally record our work output in the form of “calories burned”.
“Calories” are a measurement of the heat units that come out of nutrients in a bomb calorimeter.
Is the human body a bomb calorimeter? No.
When we are active are we really burning “calories”? No.
We are “burning” ATP.
So the goal should then be how do we burn the maximum amount of macronutrients with the least amount of ATP?
Then, using that pathway, how do we burn as much ATP as possible to maximize the amount of ingested and stored macronutrients burned?
I dug into my old manuals and found this:
ATP-PC system: 1 ATP per unit of PC
Fast glycolysis: 2 ATP per molecule of glucose or glycogen
Slow glycolysis: 38 ATP per molecule of glucose of glycogen
Fatty acid oxidation: 100 ATP per molecule of glucose or glycogen
Turning that around, we get this:
ATP/PC: 100 ATP = 100 PC
Fast glyc: 100 ATP = 17 molecules glycogen or glucose
Slow glyc: 100 ATP = 2.6 mol’s glyc or gluc
Fatty acid ox: 100 ATP = 1 molecule fatty acid
So no wonder steady-state cardio doesn’t burn much fat. For every “calorie” of ATP burned in a lactic sprint, we burn 17 TIMES as much glycogen reserve as we would with the same amount of work done in a “steady-state” manner.
Then during the next 24-48 hours, while our bodies are at rest, we dip into fat stores to replenish glycogen stores via gluconeogenesis.
Is this right? Is this how it works? I didn’t take biochemistry in college so someone please help me out if my numbers aren’t right.