In Steven Low's article states " EPOC (excessive post-exercise energy consumption) has generally been the explaining for the phenomena superior fat loss for HIIT versus ET. This theory is incorrect". I read the pubmed abstracts of the study this was based on (Laforgia, et al. 2006) and the related studies in Pubmed and have the following questions/points of view/thoughts.
1. How was EPOC measured? The abstracts did not say. How does on measure oxygen (O2) consumption? O2 Uptake can be measured easily, was this measured? If one only looks to when O2 uptake returns to normal, this does not correlate to when O2 consumption returns to normal. O2 uptake and O2 delivery (DO2) are generally 3-10x in excess of O2 needs (MVO2). So, you can have O2 uptake return to normal, but still have elevated O2 consumption.
2. How was "EPOC comprises only 6-15% of the net O2 cost of exercise" determined? Again, did they look at how much O2 was uptaken during exercise and after how long until O2 uptake returned to normal?
3. The neuoroendocrine response to exercise results in both an increase in Beta oxidation and glycolysis. The purpose of both of these is energy production (ATP). Beta oxidation gives us the substrates NADH, FADH2, and Acetyl Co-A. Beta Oxidation requires O2 (O2 consumption). Next, glycolysis also gives us a small amount of ATP, but also substrate (pyruvate), which ulitmately leads to NADH and FADH2. NADH and FADH2 require O2 (more O2 consumption) to give us ATP (energy). Is this O2 consumption considered as part of EPOC?
I just do not see how someone can measure O2 consumption or really how O2 consumption (not uptake) can be separated from the oxidative phosphorylation. Finally, when the term EPOC was "coined" does anyone know how it was used? Was it meant to refer not just to O2 consumption, but beta-oxidation, glycolysis, oxidative phosphorylation?
All points of view are welcomed. It is nice to find an environment where my main interests....exercise and physiology/pharmacology interact. Now if anyone wants to start a thread on Alpha-2 receptors, I am in