The ins and outs of carb loading

           Carbohydrate loading or carb loading for short is often misinterpreted as eating carbs the night prior to a long aerobic event. While is it important to eat carbs the night prior it is not classified as carb loading. Carb loading is a structuring your nutrition several days ahead of time. Common practice is to consume 8-10grams of carbs per kilogram of body weight three days ahead of the aerobic event. For example, if I am 86kg (190 pounds) then I would plan to eat between 688-860 grams of carbs per day for the next three days in order to prepare for the race. In the event of a marathon distance or above it may be beneficial to consume a larger amount of carbs. 10-12g of carbs per days two days prior is recommended. A few things to keep in mind when carb loading the various types of carbs may have counterproductive results nutritionally. Carbs that are higher in fiber may give off the feeling of being "full" due to delayed gastric emptying leading to bloating thus not hitting Nutrional goals (nothing worse than trying to eat more food when you feel full). Prebiotic fiber stimulates bacteria growth in the stomach which may lead to more trips to the bathroom. Another concern is potential weight gain from increased carbs. When carbs are digested, they are either sent to the muscles for glycogen storage (energy source). Increasing the amount of water within the muscle. Carbs that are not used for muscle glycogen are stored in the liver for liver glycogen. (Skeletal muscles glycogen is used for muscles and liver glycogen is stored for the entire body). A cautionary tale is to practice this method and use trial and error on types of carbs consumed. Rule of thumb is to not experiment with nutrition before a race. Using carb loading techniques has been shown to increase glycogen storage up to 20%-40% in males. I say males because females historically have had mixed results from carb loading due to not having enough total caloric intake. To really make carb loading effective one should taper off before a race. Tapering is simply a planned reduction in training. This can be accomplished more or less in two methods: linear and step. Linear is the gradual reduction in training, and step is a more aggressive approach by abruptly reducing training. Tapering along with carb loading is the sure-fire way to saturate muscle glycogen.

        Why fill up glycogen storage? Glycogen is energy currency used by the body during exercise. A good metaphor is filling up your gas tank before a road trip. Yes, road trips with a half a tank are certainly doable but requires more stops. Filling up the gas tank before driving enables your car to go further. Same as filling up your energy levels enables your body to go further before re-fueling. Glycogen is the bodies preferred method of fuel for exercise for more intense exercise.

        Some of the guidelines pertaining towards carb loading for aerobic events typically involve at least 90 min of exercise at roughly 70%-80% of your Vo2 max. 90 min of aerobic events include a 10-mile run (unless you're really competitive runner), half marathon and of course a marathon. 

        To summarize carb loading is appropriate for aerobic events that exceed 90 min. With a recommended intake of 8g-10g of carbs per kilogram of body weight (or 10g-12g of carb). Also, experiment with these techniques is paramount to avoid any race day GI issues.