Mar 8, 2018
Hitting the Wall
Laura Anderson

At the University of Colorado, distance runners train six days a week, with the women logging anywhere from 45 to 75 miles per week, and the men running 70 to 100 miles. As you can imagine, fueling this high level of activity is no easy task.

Our fueling plan for distance runners starts with fresh food. Then, we provide lots of different ways for athletes to have access to it and educate them on nutrient timing. Combined with comprehensive physiological monitoring of potential relative energy deficiency syndrome (RED-S), our fueling program plays a significant role in athlete recovery and supports our runners being able to train and compete at an elite level. (A closer look at the program can be found here.)

If University of Colorado distance runners have abided by my pre-training nutrition and hydration guidelines, they should have no problem getting through workouts. But sometimes the busy life of a student-athlete prevents them from doing this, and they experience the dreaded “bonk.”

The bonk, or “hitting the wall,” is an indication that the body’s glycogen stores are depleted, and the athlete’s ability to work at high levels may be compromised. Symptoms include feeling weak and tired, being shaky, sweating, dizziness, and lightheadedness. Most athletes have experienced this dreadful feeling, and it is next to impossible to continue at the same intensity pre-bonk, even for the most metabolically efficient runners.

During individual nutrition sessions with each runner, I do my best to help them plan strategies for keeping the bonk at bay. When training or racing, I encourage them to have products on-hand such as a sport drink, gels, bars, or blocks to provide their body with an endogenous form of carbohydrate and allow them to complete the practice or meet at the intensity expected of them.

Presently, there is a lot of conversation in the endurance world about improving performance by following a low carbohydrate diet. While there is solid research showing an increase in the body’s ability to utilize fat at a high intensity, thus preserving glycogen stores, there isn’t solid evidence of actual performance improvement in real-life endurance athletes. Until that time, I will continue to educate the athletes on how to periodize their carbohydrate consumption around training sessions and body composition goals during specific times of the year.


Laura Anderson, MS, RD, CSSD, is Director of the Performance Nutrition Department for University of Colorado athletics.


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