We think of this as the big bowl of pasta the night before the big race or pizza to provide the fuel for that long event coming up. Why do we do this? Carbohydrates are the body’s main fuel source the extract energy from and this is particularly important for endurance athletes. Is this really conducive to improving one’s performance? Let’s check it out.
What is the idea?
This idea came from previous research involving 2 days of glycogen depletion followed by 3-4 days of glycogen repletion, consisting of ingesting about 65-70% of calories as carbohydrates. The idea is to produce enough stored glycogen to fuel the muscles for long strenuous exercise. Feeding in this ideal time window can “maximize” liver and muscle glycogen levels.1
Glycogen is the body’s main source of stored carbohydrates, aka energy. This usually gets depleted after 90 minutes of aerobic exercise or can get drained quicker (between 30-60 minutes) after high-intensity exercise. Previous research has revealed that administration of carbohydrates helps delay the onset of muscle fatigue up to 20% in endurance events lasting longer than 90 minutes.1
According to a recent study, ingestion of about 70% carbohydrate after an overnight fast before a long bout of exercise (>70 minutes) improved aerobic performance, increased utilization of muscle glycogen, and increase carbohydrate oxidation (or breaking down carbohydrates for energy.) Others showed that carbohydrates worked better for performance when ingested several hours before the high-intensity exercise. This review also noted that “the need to ingest pre-exercise meals or snacks goes up when athletes have consumed relatively small amounts of carbohydrates in the days leading up to a competition OR proper rest or recovery had not been instilled.
Do you really have to do this?
I spoke with Dr. Jason Barker of The Natural Athlete Clinic in Colorado. After 90 minutes of exercise, your body needs it’s glycogen stores to be replenished but requires complex nutrition. Instead of loading the body with straight sugar, adding in a source of fat, protein and carbohydrates serves as better fuel for a long ride or run. We are still losing muscle during these long bouts of exercise and require proper fuel from protein to maximize recovery from that exercise. Fats also decrease digestion and can create a steadier stream of energy flow.
Is there really much of a benefit to carbohydrate loading?
Yes and no. Glycogen storage and utilization should be steady over time, aka not just in the days leading up to the race. Also, there are other macronutrients that are responsible for generating energy and restoring the body. Personally, I would rather not deplete myself of carbohydrates for a period of time. Glycogen depletion training is very taxing on the system, makes it very hard to train, and although the body may adapt, I do not believe it has to be that violent. I can attest to this from my own experience. If my carbohydrates were low, my performance tanked. I felt very tired, I was not recovering properly and that made me very discouraged. Having a steady amount of carbohydrates during my training was where I saw the best results.
As mentioned, if one is not recovering properly, then the question of the amount of protein one is consuming should be addressed as this helps build new muscle. Sleep is also going to be another big factor in how well glycogen stores are maximized as improper sleep can decrease glycogen storage potential.
The moral of the story, carbohydrates are necessary for performance but should be steady throughout training. Lower glycemic carbohydrates should be the focus along with each meal consisting of a complex carbohydrate, fat, protein, and veggie. Pre-workout, some sort of complex carbohydrate should be consumed 30 – 60 minutes before exercise. During a race, include simple carbohydrates mixed with protein and fats. After 90 minutes this can be in 30 or 60 minute intervals. This helps to maintain optimal blood glucose levels. If you are fueling properly during the exercise, you have at least 2 hours before you need to refuel. This can also be done with a complex meal. For me personally, I love a nutrient-dense shake. This also decreases cortisol levels which can improve muscle recovery.
Other lifestyle factors should include getting adequate amounts of sleep and water and decreasing sugar intake which can stress the adrenals further and dehydrate the body.
References:
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Kershik, C. International Society of Sports Nutrition Position Stand: Nutrient Timing. Journal on International Society of Sports Nutrition. 2017. 14(33). Article retrieved from https://jissn.biomedcentral.com/articles/10.1186/s12970-017-0189-4.
