Clyde, You say in your guide (Endurance Nutrition Book) no more than 200 cal/hour. So if I'm burning 900 cal/hour and ride 8 hours, that necessarily means that 700 of those are fat (and some protein), at least on an asymptotic basis, right?
Today I skated hard for about 2 1/2 hours using 480 calories of Accelerade in 2 liters water, with a few 5 min breaks thrown in (socializing). That felt about right, as did hydration. Interesting...that's 192 calories per hour, right on target with your recommendation. Lloyd
ANSWER: You are correct that there is a mismatch between how much fuel muscle will absorb and the rate at which it burns it. Muscle can burn around 1000 Cal / hour but can only absorb about 1/4 of that amount per hour. The result is inevitable fatigue. However, we can store more carbs in the muscle before training even begins with carb loading, we can optimize muscle fueling during training by pacing our calories, and we can optimize fat availability and utilization by not spiking our insulin levels (again, by pacing our calorie consumption) during training AND by not training at a higher pace than our target. As intensity increases, sugar burning goes up and fat utilization goes down, and the sugars burned are obviously lost for the rest of the race since muscle can only absorbe sugars at a slow rate compared to the rate it is burned; in other words, training at a faster pace than intended will rob you of sugars that you need later. This happens to athletes who are so excited about a race that their beta endorphins reduce their pain sensation and they race faster than their intended pace, thinking they are having an amazing race day, but then they bonk later on. The athlete needs to take advantage of all fuel sources with proper training (increases fuel storage and transport capacity), nutrition (increases recovery and fuel availability), pacing (achieving the balance of sugar to fat burning that will enable the athlete to maintain some sugar reserves till the end of the race) and tapering (to ensure full recovery for competition so that the carb load is not lost to recovery, but actually goes to increasing glycogen as intended). Most of the calories burned during the most intensive training hours are in fact carbohydrate, but we can't replace them at a sufficient rate to maintain such a pace, so the higher the intensity the sooner we are forced to reduce our pace as the body is forced to use more fats when glycogen runs low. Or, worst case scenario, if sugars run out to the point that even fats can't be burned as efficiently (sugar burining produces pyruvate, which speeds up fat burning), then you bonk and have a hard time even walking. In other words, the athlete needs to have at least a small amount of sugar reserves to perform effectively. Achieving this, along with maintaining hydration for circulatory function and nerve excitation (avoiding cramping from high sodium or hyponatremia from low sodium concentrations), are the key goals of sports nutrition during training and competition.
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