Two weeks ago, I was inspired to write my nutrition blog based on conversations I had with a few runners that made me realize how much people don’t understand physiology. Sports nutrition is all about physiological needs, which is different than needs for activities of daily living. I hope all that read the nutrition blog post gained that understanding. I discussed macronutrient needs and, more importantly, intensity-based fuel utilization. At greater intensities, carbohydrate metabolism reigns supreme, yet we have a limited storage capacity to get us to the marathon finish line. This problem is solved by becoming a more fat-adapted athlete, or more easily achieved through race day carbohydrate consumption. Even the fat-adapted athlete requires race day carbohydrates because they are a major player in metabolizing fat storage into fuel.
The complaint from many runners is that their stomach cannot tolerate carbohydrate gels and/or fluids and the research shows that marathon runners under fuel. As stated in the previous blog post, the current recommendation for carbohydrate consumption is 30-60 grams per hour, up to two hours of running and even greater for runs longer than two hours. The reason is that carbohydrates provide an ergogenic effect, which means they are “performance enhancing”. Run out of gas in your fuel tank and you will not get anywhere anytime soon, including to the finish line. Makes sense, doesn’t it? Research reveals 73% of marathon runners consume less than 30-60 grams per hour of carbohydrates during a marathon race (Stellingwerff, 2012).
Recently, nutrition researchers have been heavily studying gut adaptability to increased carbohydrate for an ergogenic effect. The topic is way beyond my scope and the understanding of my readers. But in basic terms, the stomach can be “trained” to tolerate and uptake more carbohydrates. Exercise physiologist, Dr. Trent Stellingwerff conducted a case study of nutritional and training periodization variables on two Canadian elite marathon runners. He developed nutritional periodization strategies which included but not limited to adapting the gastrointestinal tract to accept increased fluid and carbohydrates on race day. Gut adaptions in the form of an increase in carbohydrate transporters allowed a higher level of carbohydrate gel consumption and fluid on race day, allowing for a maximal ergogenic effect of the carbohydrates. The elite runners reduced their personal best time in the marathon by 2:36 and 5:30 by training their stomach to tolerate 30-60 grams of carbohydrates per hour. Remember, the faster you are, the less room for improvement there is. These are elite runners. Elite runners improve by seconds, not minutes. The last time the world watched an elite runner decrease his marathon time by more than two minutes, it was by Eliud Kipchoge in the Nike Breaking2 Attempt, where many other variables were intentionally manipulated to achieve superior results.
How might the nutritional strategy of adapting the gut to tolerate more carbohydrates impact me and you, the run of the mill recreational marathon runner, coupled with appropriate (smart) training? How about up to a 4% improvement in race time!?! Research has supported adapting the gut to tolerate carbohydrates on race day, along with a well-designed and executed training plan and racing strategy, could improve a marathon time from 3:50 to 3:40. So how many of my readers have missed their goal time, Boston Qualifying time, or even worse, their acceptable Boston time by a minute or two? If your training is on point and your daily nutrition is on point, it is time to change your race day nutrition strategies to keep your engine running.
Runner Image: Darryl and Tricia Sol
Stellingwerrf, T. (2012). Case study: Nutrition and training periodization in three elite marathon runners. International Journal of Sport Nutrition and Exercise Metabolism, 22, 392 -400.