Originally Posted by Rockadile
This site says:
http://www.cptips.com/nutrtn.htm
"In order to avoid the "bonk" (the shift to fat metabolism with an accompanying deterioration in performance), supplemental carbohydrates need to be eaten during the early stages of rides that will be more than longer than 1 to 2 hours in length to supplement (and thus spare) the body's own glycogen stores."
I thought if I was doing aerobic exercise that I started burning fat after 20 min.
They are saying 2 hours after glycogen stores are depleted that I will start metabolizing fat, thus zapping me of riding energy, but If Im metabolizing fat I don't care how much energy I have to ride. Again though I thought I was metabolizing fat after 20 min of aerobic exercise.
Actually, the trick is to keep enough glucose in the system to keep mental function. Lipid/Protein metabolism provides 5X the energy of Glucose metabolism, but you need the glucose to keep your brain working due to the fact that the CNS can
ONLY metabolise Glucose. The Liver used to produce reserves to glucose from Glycogen stored in the muscles and liver. To understand this better you need to read up on the Citric Acid Cycle( Or Kreb Cycle) for ATP production in cellular metabolism as well as the Lipid and Protein Cycles (Both anaerobic). Usually, when you are in a hard bonk, it's more a deterioration of mental function that keeps you from being able to function.....you can't think straight! You aren't able to take in enough calories, by the way to overcome the deficit in calories in vs calories burned on a long ride, and that's why pre-ride loading and post ride recovery is so important if you are doing something longer than a couple of hrs.
