The purpose of carb loading is to enhance muscle glycogen prior to extended aerobic endurance exercise. The theory was developed in 1931 and has taken a variety of forms since its induction into the fitness realm. First, let’s talk about why we call them carbs in the first place. Carbohydrates are composed of carbon, hydrogen, and oxygen with the acronym of CHO, hence why we’ve shortened the structure to “carbs.” Their primary role is to serve as an energy source and can be classified into three groups according to the number of sugar molecules they contain.
Monosaccharides – glucose, and fructose (fruit)
Disaccharides – lactose (dairy), and sucrose (table sugar) Limit these sugars as much as possible.
Polysaccharides (complex carbs) – fiber, starch, and glycogen (stored glucose)
Glucose is the most common monosaccharide and is found as circulating sugar in the blood. The storage form of glucose is called glycogen, of which 2/3 is found in skeletal muscle and 1/3 in the liver. It’s the glycogen that is the most important when referring to carb loading. The intent is to overload your glycogen stores so that it can be broken down into glucose and utilized for energy during the physical event. The most accepted method of carb loading with the fewest side effects (water retention, weight gain, digestive issues) is 3 days of a high-carbohydrate diet along with tapering exercise the week before competition and complete rest the day before competition.
The following table is an easy and effective way of gauging your carb intake for a given workout or event. The Beast on the Bay will take you between 1.5 and 3.5 hours, depending on your aerobic conditioning. 10 miles at a pace of 3 mph would take 3 hours and 20 minutes. Most people with adequate training should pace between 4 and 6 mph, which would take between 1 hour and 40 minutes and 2.5 hours. Based on the recommendations presented in the table, you should consume 4 -6 grams of carbs per kilogram of body mass (BM). To calculate this amount, use the following equation: BM/2.2 x 4. For example, I weigh 86 kg and should therefore consume 345 grams of carbs per day for the three days prior to the Beast. This is assuming that I am giving my best effort for the entire 1.5 hours. If I were just walking, I would only consume about half this amount. It’s imperative that you find out how your body reacts to high carb consumption prior to the week of the event so you can make adjustments as necessary.
-Dave Hopkins, M.S. ACSM-HFS, NSCA-CSCS
LECOM Medical Fitness & Wellness Center
5401 Peach Street Erie, PA 16509