Getting race-day nutrition balanced is a science, and because we don’t all have our own personal physicians, chemists and nutritionists locked away in our medicine cabinets, it takes quite a bit of trial and error to find the optimal arrangement. The following are some general guidelines both men and women can adhere to as a template or stable starting point.
Three days prior to the event you should be consuming 10 grams of carbohydrate (CHO) per kilogram of body weight. This ensures that your muscles will be fully stocked with enough easily accessible glycogen so you don’t go into the race with a deficit leaving you limp and hungry. Liquid meal supplements can be used pre-exercise for those who have difficulty digesting solid foods and they are ideal to use close to competition to prevent nausea and vomiting. A high-CHO, low-fat snack is easily digested and normalizes blood sugar. Avoid fatty meals or snacks because they may stay in your stomach for long periods of time. The meal should be moderate in protein–just enough to satisfy hunger. You should aim to eat your pre-race meal 3 hours ahead of the start time so that your body has enough time to fully digest and balance its systems. If you have only 1-2 hours ahead of time to eat, the number of grams of CHO you should ingest corresponds with the hours you have left ( 1 hour before the event = 1g/kg, 2hrs prior = 2g/kg).
The recommended CHO intake during exercise is 30-60 grams for every hour as food and/or liquid. For sessions up to 60 minutes, plain water is sufficient and your body won’t be in any caloric deficit to necessitate eating. For sessions up to 90 minutes, an electrolyte beverage is adequate as your body will likely be sweating and demand mineral uptake without the need for excess calories. For sessions 90-180 minutes, it is best to follow the above mentioned recommended CHO intake along with 4 oz of water every 15 minutes (one mouthful is equivalent to 1 oz). It might be helpful to grab 2 cups of liquid at each aid station when racing.
One gram of sodium intake per hour is best. It can be consumed via sports beverage, salt tablets, or salty snacks at aid stations. If you are a big sweater you should add salt to your sports drink. Be careful when using salt tablets; if they are used cautiously and with plenty of fluid they can be an acceptable way to replenish sodium. However, they generally contain much more sodium than the amount lost from perspiration. With inadequate fluid intake, a concentrated salt solution is introduced into the small intestine and draws water from the blood stream.
The volunteers at aid stations are there to assist you in getting just what you need, and most are runners themselves. They understand the nutritional demands of trail/ultra-running and will be prepared to get you on your way. It will decrease time spent at aid stations when you already know what foods work for you and if you carry something with you just in case–it is always best to eat and drink before you feel hungry and thirsty. Experiment with your eating schedule and see what works best for you.