Glucose and Fat Oxidation: Bomb Calorimeter Be Damned
Figure 1
Anaerobic glycolytic metabolism is depicted in red, aerobic metabolism in black print, from left to right. At the top of the figure, both comprise a respiratory oxygen uptake to energy cost conversion of 1 liter of oxygen = 21.1 kJ when glucose is used as a fuel. Below, the anaerobic and aerobic components of a brief bout of exercise are shown, followed by an all-aerobic recovery (represented by the term “O2 debt”) where fat and lactate are consumed at 19.6 kJ per liter of oxygen. The 1.5 kJ per liter of O2 uptake difference is accounted for by entropy changes with pyruvate formation and by enthalpy changes when lactate is produced.
