Carbohydrate manipulation across your training cycle is one of the simplest nutritional strategies to boost physical and mental fitness. For more than 20 years, I’ve used this strategy on myself, as well as with many of the athletes I coach, and have had great success.
In a nutshell, you supplement with carbohydrate before and during long runs early in your training cycle. Then, you wean yourself off carbohydrates for long runs in the middle portion of your training cycle. Finally, you sprinkle in some low-carb runs in the final few weeks of training, but balance these with long runs that practice your race-day carbohydrate fueling. The end result is that you get the performance benefits from using carbohydrate before and during long runs—higher quality long runs—but also get the positive physical and mental benefits from low-carbohydrate training, including exposure to race-like suffering, greater fat burning and carbohydrate sparing.
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When training for longer races like a half marathon or marathon, there are three main goals:
1. Increase the proportion of energy at race pace that comes from fat as opposed to carbohydrate. Race-pace running requires energy from both fats and carbohydrates but carbohydrate stores are limited. So, if at race pace you can get a higher percentage of your energy from fat, you’ll spare those precious carbohydrate stores.
2. Increase the total store of carbohydrate available. Think of this as having a larger fuel tank. You’ve probably read that carbohydrate stores typically last 90-120 minutes before they get low, so if you have a larger tank and burn the fuel at a slower rate, you’ll have more fuel at end of the race. No more hitting the wall for you!
3. Get acquainted with the “pain” at the end of long races. Racing your best half marathon or marathon is going to be mentally challenging. It will require more mental fortitude than you are often used to, so while training for the race, you actually want to experience the level of fatigue—physical and mental—where the brain is screaming at you to stop. You want to have some experiences of running in extremis.
You’ve probably read about the central governor theory whereby the brain, if it feels threatened by your rapidly depleting energy stores or tired muscles, will consciously send greater and greater sensations of fatigue and can actually cut the power to the muscles and slow you down. This leads to the “wall” or “bonking” that runners fear. Given that, some of your training must expose your brain to these feelings so it will feel less threatened on race day.
Manipulating your carbohydrate intake across your training plan can help you optimize each of the adaptations.