Nutrition in Endurance Training for Marathon and Long Distance Runners
Distribution of Macronutrients for Exercise Performance
When determining macronutrient (macros) distribution we are looking at the total percentage of protein, carbohydrates and fats that make up the total consumed calories in a person’s daily diet. A balanced macro ratio would consist of consuming about 50% of calories from carbohydrates (3 to 5 g/kg/day), 20% from protein (0.8 to 1 g/kg/day), and 30% from fat (0.5 to 1.5 g/kg/day). This recommendation aligns with the U.S. Dietary Guidelines, Academy of Dietetics and Nutrition and the American College of Sports Medicine. Endurance training more than 3 times per week for longer than 60 minutes will increase your energy needs, or caloric intake.
What Does the Research Say?
During exercise the body is relying on glucose stores (glycogen) to keep producing energy out of the cell to keep our muscles pumping and body moving. This process is called cellular respiration which mainly uses glucose to produce this energy. Glucose comes from carbohydrates, so consuming carbohydrates is important to build up these glycogen stores to give our bodies the glucose it needs to keep producing energy with intense exercise or long, endurance workouts. Marathon and long distance runners should aim to meet the caloric needs of training by following a periodized strategy of rotating macros dependent on pre- or post-season training and competion. This is a process called nutrition periodization. Increasing the amount of carbohydrates consumed before long duration exercise can help reduce glycogen depletion. However, reducing consumption of carbohydrates before low-intensity workouts, active rests, post-season recovery and/or may improve cell function and fat oxidative capacity. The duration of exercise and intensity training cause the cells to use fat stores to produce energy in the cell, but a continuous stream of carbohydrates is needed to breakdown those fat stores. Runners have a much smaller storage supply of glycogen than fat, and the body prefers to use the glycogen at high levels of exertion.
Pros and Cons
Eating within your macros can give someone a lot of flexibility within their daily diet, however tracking your calories and macros may be triggering for those who have a history with disordered eating patterns. In one study, researchers designed an experiment to test nutritional support during marathon races and the performance of the runner in comparison to no nutritional support during the race. Results determined that consuming in-race nutrition with 100 calorie sports gels consisting of mainly carbohydrates 4 times spread evenly throughout a marathon race improved running performance (longer distance in same period of time) compared to using no in-race nutrition.
Beneficial Supplements
Electrolytes including sodium and potassium are important to include during training, endurance runs, and competitive races. Your body will continuously sweat during high intensity and endurance exercise which can create an imbalance in electrolytes that can lead to dehydration and hyponatremia. Especially in hot and humid temperatures, it’s important to stay hydrated and consuming water alone will not be enough. Sodium and potassium both work together to bring glucose into the cell and produce the energy we need from our cells. Two supplements that you can use to make sure your consuming electrolytes while rehydrating is Liquid IV and LMNT. Both are sold in many local grocery stores and come in easy-to-use pouches that you can add to water on the go. Another supplement you can use while endurance training and in competitive races are Gatorade chews. Gatorade chews provide a blend of both glucose and sucrose, sugars found in carbohydrates, that are readily absorbed and used for energy in the cell to keep you going.
References
Raymond, J. & Morrow, K. Krause and Mahan’s Food & The Nutrition Care Process. 16th ed. Elsevier; 2023.
Tiller NB, Roberts JD, Beasley L, et al. International society of sports nutrition position stand: nutritional considerations for single-stage ultra-marathon training and racing. J Int Soc Sports Nutr. 2019;16(1):50. Published 2019 Nov 7. doi:10.1186/s12970-019-0312-9
Cook C, Chen G, Hager WW, Lenhart S. Optimally controlling nutrition and propulsion force in a long distance running race. Front Nutr. 2023;10:1096194. Published 2023 May 18. doi:10.3389/fnut.2023.1096194
