Here's the question. How will dietary carbohydrate alter the metabolism of a well fed athlete performing steady-state exercise at 60% Max Hr, which is assumed to be 100% aerobic muscle fiber recruitment for purposes of this question. However, basal metabolic requirements still need to be accounted for.
Here's the control subject:For sake of simplicity, 30-year-old male, 170lbs, will expend 1200 cal during 3 hours of sub-maximal exercise while ingesting enough water. (test subject is hydrated as well)
Here's the test subject: Identical twin of control subject, 170lbs, will expend 1200 cals during exercise, but will ingest 200cals of a 50/50 fructose/sucrose blend at 1 hour 2 hour mark during the workout.
Obviously, one athlete has accumulated a 1200 cal deficit, and other has also expended 1200 cals but ingested 400 cals of simple sugars - therefore that athlete is at an 800 cal deficit.
Question 1)Is it possible to ascertain the difference of stored energy-substrate utilization between the two athletes as a result of 1200 cals or metabolic activity?
Question 2)Is it possible to identify the whether or not the ratio of energy substrate utilization involving fatty-acid oxidation and adipocyte mobilization is affected?
Essentially, we know that both athletes are down 800 and 1200 calories respectively. But what every single lame fat-head wants to know is - which athlete "burned the most fat".
We also know that eventually, homeostasis will restore any disturbance of balance of metabolites in the blood by oxidizing fat. So the guy who didn't eat carbs does eventually - "burn the most fat."
But my Richard Cranium question is:In this scenario, how much does carbohydrate ingestion during exercise contribute to energy expenditures and how much of the recent carbohydrate is actually replacing energy substrates that are already mobilized and ready for oxidation. I'm trying to understand how the body discriminates between adipocyte mobilization and recently metabolized [created] blood-born energy stores. (that is, the carbs before they turn into glycogen or non-"free" fat cells)
See if you can figure that out from reading this.
Here's a great link, previously supplied by an esteemed forum member:
Here's the gist of the link:
Regulation of Fatty Acid Metabolism
In order to understand how the synthesis and degradation of fats needs to be exquisitely regulated, one must consider the energy requirements of the organism as a whole. The blood is the carrier of triacylglycerols in the form of VLDLs and chylomicrons, fatty acids bound to albumin, amino acids, lactate, ketone bodies and glucose. The pancreas is the primary organ involved in sensing the organism's dietary and energetic states by monitoring glucose concentrations in the blood. Low blood glucose stimulates the secretion of glucagon, whereas, elevated blood glucose calls for the secretion of insulin.
The metabolism of fat is regulated by two distinct mechanisms. One is short-term regulation, which can come about through events such as substrate availability, allosteric effectors and/or enzyme modification. The other mechanism, long-term regulation, is achieved by alteration of the rate of enzyme synthesis and turn-over.