endurance athlete nutrition

Athlete

Endurance athlete

An athlete's diet should be composed of 55-65% carbohydrates, 12-15% protein and 20-35% fat. Heavily trained athletes, including endurance athletes can consume up to 4000-7000 calories a day, depending on age, gender and of course level of activity (Housh et al., 2017). The ISSN recommends  40–70 kcals/kg/day, which is approximately 2000-7000 calories/day for an athlete 50-100kg. The caloric intake is even more for elite athletes  (Kerksick et al., 2018). 

Carbohydrates

It is recommended that athletes intake 6-10 grams of carbohydrates/kilogram of body weight a day (Housh et al., 2017). Carbohydrates facilitate energy production by taking the form of blood glucose and stored glycogen (Housh et al., 2017). The International Society of Sports Nutrition (ISSN) recommends 8-12 grams/kilogram/body weight a day, in order to maximize glycogen stores (Vitale, K., & Getzin, A., 2019). 

Before an event or competition, endurance athletes should have a small amount of carbohydrates - typically 200-300 calories at least 3-4 hours before exercising can enhance performance (Housh et al., 2017). Vitale & Getzin, (2019) recommend 1-4 grams/kilogram of body weight 1-4 hours before the event. Athletes should also fuel during the exercise. It is recommended that athletes consume 30-60 grams of carbohydrates every hour divided in 15-20 minute intervals. This helps maintain blood glucose levels when glycogen stores are running low or are depleted. More specifically, in an ISSN review, they recommend .7 grams of carbohydrates/kilogram of body weight every hour, mixed in a 6-8% solution in 100ml of fluid (Kerksick et al., 2018). Carbohydrates taken before or during the competition or event should be low in fat and fiber, in order to avoid any gastrointestinal distress (Housh et al., 2017).

Immediately following the exercise, the athlete should consume 1-1.5 grams of carbohydrates per kilogram of body weight in two hour intervals for six hours. This will help replenish muscle glycogen stores. Delaying this process can result in early onset fatigue (Housh et al., 2017).

Protein

For endurance athletes, 1.2-1.4 grams per kilogram of body weight per day. Although it is recommended that strength athletes intake more protein each day (1.4-1.7 grams per kilogram of body weight per day), endurance athletes pull more energy from protein sources than strength athletes do. Compared to untrained individuals, the extra amount of protein each day can help with the repair of muscle tissue (Housh et al., 2017). In regard to the quality of protein, there are 23 amino acids, and 13 of which are synthesized in the cells. The body still requires 10 essential amino acids, which can be supplied through eating animal products. However, vegetarians have to fulfill their amino acid intake through fruits, seeds, roots and leaves. Vegetarians are encouraged to eat 1.3-1.8 grams of protein per kilogram of body weight a day (Housh et al., 2017). However, the ISSN states that athletes involved in intense, high volume training should have 1.7-2.2 grams of protein/kilogram of body weight a day  (Kerksick et al., 2018). 

Fat

Athletes generally are encouraged to intake 20-35% of calories from fat and no more than 10% of that from saturated fats (House et al., 2017). Dietary recommendations for fat intake for athletes is similar to non-athletes, ranging from .5-1.0 gram/kg/day (Kerksick et al., 2018). Fatty acids are rich in energy, providing 9 calories/gram. At the start of exercise, the fatty acid circulation immediately decreases and as the exercise bout continues, the circulating fatty acid increases as a result from fatty acid stored in the adipose tissue. However, a high fat diet does not necessarily improve endurance performance and is not recommended for endurance athletes (House et al., 2017). 

Vitamins

For endurance athletes, one supplementation that I believe is necessary to mention is iron. Taking iron supplements is necessary for those experiencing sports anemia. Many endurance athletes and vegetarian athletes suffer from low hemoglobin and hematocrit values (Housh et al., 2017). 

Protein + Carbohydrates

Kerksick et al. (2017) cites a study from Ivy and colleagues. They had trained cyclists perform a 3-hour cycling exercise at an intensity of 45-75% V02max. The participants ingested 7.75% carbohydrate or 7.75% carbohydrate and 1.94% protein solution before the event. They found a significant improvement in performance for the carbohydrate and protein group. 

Summary

A serious endurance athlete should consume anywhere from 4000-7000 calories a day. Each day, the athlete should consume 8-12 grams/kilogram/body weight of carbohydrates, 1.2-1.4 grams/kg/body weight of protein, and .5-1.0 grams/kg/body weight of fat. It is suggested that before the event and/or competition, athletes should consume 200-300 calories worth of carbohydrates that are low in fat and fiber 3-4 hours before. According to Kerksick et al. (2017), a small amount of protein should be added to this. During the competition or event, .7 grams of carbohydrates/kilogram of body weight should be consumed every hour, mixed in a 6-8% solution in 100ml of fluid (Kerksick et al., 2018). Finally after the event/competition, 1-1.5 grams/kg/body weight should be consumed immediately after. Athletes experiencing sports anemia may also want to consider taking iron supplements. Finally, if the endurance athlete is a vegetarian, it is recommended that they consume slightly more protein each day at 1.3-1.8 grams/kg/body weight. 

Housh, T. J., Housh, D. J., & DeVries, H. A. (2017). Applied Exercise & Sport Physiology With Labs. Routledge/Taylor and Francis Group. 

Kerksick, C.M., Arent, S., Schoenfeld, B.J. et al. International society of sports nutrition position    stand: nutrient timing. J Int Soc Sports Nutr 14, 33 (2017). https://doi.org/10.1186/s12970-017-0189-4

Kerksick, C.M., Wilborn, C.D., Roberts, M.D. et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr 15, 38 (2018). https://doi.org/10.1186/s12970-018-0242-y

Kerksick, C. M., Wilborn, C. D., Roberts, M. D., Smith-Ryan, A., Kleiner, S. M., Jäger, R., Collins, R., Cooke, M., Davis, J. N., Galvan, E., Greenwood, M., Lowery, L. M., Wildman, R., Antonio, J., & Kreider, R. B. (2018). ISSN Exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition, 15(1). https://doi.org/10.1186/s12970-018-0242-y

Vitale, K., & Getzin, A. (2019). Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients, 11(6), 1289. https://doi.org/10.3390/nu11061289