This article was written by Kevin Sprouse, DO, CAQSM. Dr. Sprouse is a team physician for the Cannondale Pro Cycling Team, has a degree in exercise science, and is board-certified in two medical specialties. He practices Sports Medicine at Provision Sports Medicine in Knoxville, TN. Race day can be daunting. You’ve put in the time and made the sacrifices, now it’s time to see how you can perform. It is often the final test after months training. All too commonly though, athletes end up having sub-par performances because they fail to get their nutrition right on race day. Maybe their training has been excellent, but they undermine all that preparation with poor fueling. Chances are pretty good that this has happened to you. Race day fueling is not terribly complicated, but it is incredibly important. Before we get into what you should eat and when, let’s take a look at the physiologic processes that your nutrition is supporting. Your body runs on a combination of fat and carbohydrate to fuel its activities. Efforts that are low-intensity burn primarily fat. Those that are more intense use carbohydrate (or glycogen) as their main source of fuel. Realistically, all efforts burn a combination of both carbs and fats, and that ratio is dependent on the athlete and the effort. This is important when planning your race nutrition, because you want to ensure that you support the effort appropriately. Even the leanest of us has tens of thousands of calories stored as fat, but only about 1500 to 2000 calories stored as glycogen. Depleting those glycogen stores during a race is much more likely to occur than depleting fat. If you know your body’s physiology and the effort predicted for the race, then you can make a much better decision about what and when you should eat. However, most of us have not undergone testing to determine this. While I do think many more athletes could and should benefit from this type of testing to look at their “substrate utilization”, you can certainly make some generalized recommendations without such data. For the purposes of this discussion, we’re going to assume that an athlete has arrived at the start line properly fueled. Given that, you must first look at the type of event that is being contested. Nutrition for a 10km run is going to look much different than for a 100km ultra. Here are some general guidelines for nutrition, based on event length and intensity:
- Less than 45 minutes: For these short, intense efforts, you should need no fueling during the race. If you have eaten appropriately and tapered during the days prior to the race, you will have plenty of glycogen to fuel you for this event.
- 45 to 90 minutes: Depending on your normal diet and training (ie - level of “fat adaptation”), your needs during this type of event may vary. In general though, a race of this duration will be fairly high intensity and will benefit from some carbohydrate intake. You will want to avoid significant amounts of fat, protein, or fiber, as these will slow digestion. An intake of 30-45g of carbohydrate will be all you’ll need to support this effort. This could be as simple as a packet or two of Untapped spaced throughout your race. You are basically topping up your stores and bumping your blood sugar level.
- Greater than 2 hours: Once you begin to compete at these longer distances, your race day fueling becomes much more crucial and a bit more complex. Generally, you will want to consume somewhere between 60 and 90 grams of carbohydrate per hour for these types of races. The more you eat, the more you’ll want them to be a mix of carbohydrate types. For instance, you’ll achieve better absorption at these higher levels when combining glucose and fructose (as with Skratch Fruit Drops), as each uses a different transporter mechanism in the gut. Your body is unlikely to efficiently absorb 80g of a single carbohydrate, thus leaving it in the gastrointestinal system to ferment and cause problems.