Originally Posted by Tom Stormcrowe
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.
This fits my experience perfectly. It's nice to see a good explanation.
Ocasionally on the first century of the season, I get almost home and I can still ride, and still control the bike. But, I get giddy, laugh at everything, and can't think out something complicated (like simple math). This is always before I get too tired to ride. I could get on the bike and still have plenty of power to keep going. But now I know better.
I know the feeling when it starts and I know enough to stop, rest, and eat. I also get more carefull as I get tired instead of the other way around, I know I am getting worse at quick thinking. Some others don't they just keep on going. For me liquid carbs, even just sugar water (Fruit drinks of any kind at the convenience store) get me back faster than anything else. I do lots of centuries and this is what I have to watch out for more than any other problem. I see this in new century riders, if they listen to me and get some fast carbs and rest they are OK.