Thebigturtle wrote:
Absorption rate of carbohydrates and nutrients in general is highly variable. There are so many factors that go into it. The graph that Dan Plews posted is incomplete at best and in some ways misleading as it seems to suggest one size fits all. Big fast endurance athletes like Sam Long and Kristian Blummfeldt have huge caloric needs when they are racing. Furthermore, our bodies fat oxidation is optimized for lower exercise intensities, with increasing reliance on oxidation of carbohydrates when exercising at higher speeds. The reality is, when you are burning 1200-1400 calories per hour at half IM racing intensity, you are going to need a LOT of carbs. The body as a rule is highly adaptable, and I have no doubt that larger elite endurance athletes can train their bodies to absorb 120 grams of carbs per hour, if not more. 120 grams of carbs is only 480 cals...To be fair to Dan, on the HTT podcast he agreed a guy like Sam pushing 300+W would need massive amounts of carbs for a full IM. The number he stated Sam needs was closer to the 200+g/hr range in a full IM which is probably unsustainable (this estimate was presumably based on RER/VO2 testing data). Hence Dan’s attempt to increase Sam’s fat oxidation rates.
The point where I think Dan goes wrong is locking in on the 90g/hr rate and ignoring the evidence higher rates are attainable (and necessary, for Sam). Sam is like a ticking time bomb on every full distance race and clearly has glycogen depletion issues that need to be addressed, but that’s also the case for most people who have to overcome a 5 minute deficit after every swim. That should be priority #1, and perhaps some nutritional manipulation can be used to further improve his ability to protect glycogen stores.