I've read up on carb loading and generally observed that its a common misconception you need to carb load for shorter distance races like 5k or 10k. Its supposedly only relevant in a marathon or more since glycogen stores can last about 20 miles. However, does anyone have any research articles that prove this? For example, comparing 5k performances with less and less glycogen stores in the subjects? There must be a cutoff point where a lack of glycogen will inhibit performance in the shorter distance races like 5k or 10k.
I'm also starting to wonder if glycogen loading could in fact be necessary for success at 5k or 10k. The following quotes from a runnersconnect article got me thinking:
"Additionally, there’s a factor that Rapoport didn’t take into account: new research suggests that the brain anticipates glycogen depletion and slows the body down gradually to conserve energy...
Obviously, no significant amount of sugar could make its way into your bloodstream through rinsing your mouth; the performance boost must be coming from the brain sensing that more carbohydrates are on the way.3 So it’s reasonable to propose that performance will be inhibited significantly before your body actually runs out of glycogen."
http://runnersconnect.net/running-training-articles/cience-of-bonking-and-glycogen-depletion/
So it seems the body will slow itself down if it senses glycogen becoming depleted. But at what point? When its going below 10%? 50%? 90%? and to what degree? It sounds like its possible that going into a 5k without glycogen loading could be hurting performance slightly, say if you start the race at 50% stores and your body is slowing you down sensing it is below a certain threshold. So I'm curious if anyone has some research that can refute or support these possibilities.