.Since I have been working with runners, it has left me in awe of some of the nutritional plans, or lack thereof, of so many runners. Disclaimer! I am not a registered dietician, however I am proficient at reading, interpreting, and sharing evidenced-based literature on exercise and sports nutrition, as well as exercise physiology. The latter is important for understanding energy (nutrition) consumption needs for peak performance and recovery, which go hand in hand. Without proper nutrition, one cannot achieve peak performance or recover between workouts to gain the benefits of their training, especially if it is long in duration and/or intensity.
In a time when lifestyle diets are becoming more prevalent; paleo, ketogenic, vegan, low/non-fat, etc., it is of utmost importance to understand that what the body requires for activities of daily living is different than what the body requires for sports performance and recovery. The paleo and ketogenic diet are often confused because they are both a low carbohydrate diet, with less than 10% of your daily calories come from carbohydrates. The paleo diet is higher in protein, while the ketogenic diet is higher in fat, at least 70% of daily calories from fat. The above diets, along with low/non-fat diets, are trending today, especially for weight loss, and some will argue adamantly for health benefits, real and assumed. But many runners, unknowingly are neglecting their bodies. There is a time and place for everything including when the low carb runner should be taking in carbs and when the vegan and non-fat runners are making sure they get enough protein and fat. This blog post will look at information to help runners make better nutritional choices towards their goal attainment.
Our bodies store glycogen (carbohydrates) in our muscles and liver and have the capacity to store 400-600 grams of carbs which equates to 1600-2400 kcal (Fink et al., 2011). If you google how many calories you burn during a marathon, it is going to say about 100 calories per mile as an average, approximately 2600 kcal. During a marathon, the body will run out of fuel before it reaches the finish line and this is only one reason why people sometimes “hit the wall”. Therefore, real-time race day nutrition is important to keep your blood sugar up when your liver and muscles have reached depletion. It may come as a shock that the current recommendation (remember I share the info, not determine it) is to consume 30-60 grams of carbohydrates every hour of running up to two hours and even more for over 2.5 hours of running (Jeukendrup, 2014). The American College of Sports Medicine suggests 0.7 g of carbohydrate per kilogram of body weight. A 125lb runner requires 40 grams of carbohydrate per hour to keep her motor running during a race over an hour. It requires training the gut to tolerate this much carbohydrate if you aren’t used to it, but will not be covered in this blog post.
Interestingly, the world’s best endurance runners’ diets consist of 10% protein, 13% fat, and 77% carbohydrate for the Kenyans and 13% protein, 23% fat, and 64% carbohydrates, for the Ethiopians. Although there are other factors that foster superior distance runners from East Africa, their macronutrient profile is not any different than their global competitors and are preferred for optimal training and competition at that level of competition (Wilber & Pitsiladis, 2012). Their diets are far from being low carbohydrate, high protein, or high fat. But they are competing at a level far greater than the recreational crowd. Carbohydrate utilization is intensity driven. I know most of my readers don’t know what their VO2max is, but the greater intensity that you are exercising, the greater utilization of energy from carbohydrate sources, which would be at or greater than 75% VO2max. Check out a heart rate conversion calculator at this web link: http://www.shapesense.com/fitness-exercise/calculators/heart-rate-and-percent-vo2max-conversion-calculator.aspx
At lower intensity exercise, less than 70% VO2max, there is a shift in fuel utilization to fat as fuel. Fat cells, called adipocytes can store up to 90,000 kcals of energy. Say what? Remember, we can store 1600-2400 kcal of energy from carbohydrates, which is a limited source of fuel for the marathon runner, none the less the ultra-runner, but we essentially have an unlimited source of fat storage to help us go the distance. Don’t be confused, this isn’t excess body fat, but essential fat and the storage is the same whether someone has a low or high percentage of body fat. One must understand that fat is a major fuel source for muscle cells in low to moderate exercise and when we are at rest. The only problem is that we are not very efficient at burning fat as fuel during endurance exercise. Training the body to mobilize fat as fuel would allow sparing of some of the carbohydrate storage to push out or avoid that aspect of hitting the wall altogether by becoming “fat adapted”. There are nutritional strategies that can be utilized in endurance training, Fink et al. (2012), but will not be included in the current blog post. Contact me for more info.
So far the take-aways are; fat is your friend, carbohydrates are the preferred source of fuel at greater intensity running, lifestyle diets that restrict carbohydrates or fats may not be the best for runners unless you are willing to play with different strategies and regardless of everything, race day fueling strategies reign supreme for performance. What was not mentioned? Protein as a source of fuel. Why? Protein is a horrible fuel (sorry paleo fans) and although the liver can convert non-carbohydrate sources such as proteins into glucose (carbohydrates) it is normally an end of the road situation, too little, too late to help with performance. Don’t get me wrong though; protein is essential for muscle protein synthesis (repair and building of muscle).
Assuming someone doesn’t follow a lifestyle diet and is looking to be the best endurance runner he/she can be, what should their daily diet look like during training and what else should they know about those macronutrients?
Carbohydrates: 6-10 g/kg of body weight depending on training load/intensity = 336-560 grams per day for the 125lb runner. In addition to what was already stated about carbohydrates, they also play a role in metabolizing fat as fuel and is also vital in brain function with depletion leading to confusion and delusions. Sound familiar ultra-runners?
Protein: 1.2-2 g/kg of body weight per day = 67-112 grams per day for the 125lb runner. Protein is important for distance runners because repeated muscle contractions of constant running cause protein breakdown, therefore protein consumption helps maintain protein turnover/synthesis.
Fat: 20-35% of daily calories should come from fat, which is essential in the diet for runners and non-runners. Fatty acids provide energy, produce hormones, and surround nerves to aid in proper nerve function and aid in the absorption of vitamins A, D, E, and K, which are all essential in bone strength and muscular function.
Nutritional strategies are huge in goal attainment. I hope this information allows my readers to reflect on their past racing performances and clarifies what their limiting factor was, if their training was spot on, but performed poorly on race day. In addition, I hope it is equally enlightening to all the runners that have missed their goal time by seconds or have experienced poor running times since adopting a lifestyle diet.
Runner Image: Chris Pangilinan
Fink, H.H., Mikesky, A.E., & Burgoon, L.A. (2011). Practical applications in sports nutrition (3rd ed). Burlington, MA: Jones & Bartlett Learning.
Jeukendrup, A. (2014). A step towards personalized sports nutrition: Carbohydrate intake during exercise. Sports Medicine, 44 (Suppl 1): S25–S33.
Meyer T, Lucía A, Earnest C, & Kindermann W. (2005). A conceptual framework for performance diagnosis and training prescription from submaximal gas exchange parameters: Theory and application. International Journal of Sports Medicine, 26: S38-S48.
Wilber, R. L. & Pitsiladis, Y. (2012). Kenyan and Ethiopian distance runners: What makes them so good? International Journal of Sports Physiology and Performance, 7, 92-102.