Nutritional Considerations for Runners

By: Ryan Hudson, MD, Non-Operative Sports Medicine Specialist
The University of Chicago Medicine Orthopaedics Center

As a runner, your overall diet is not only important to your health, but can also greatly impact your performance. Runners need to remember to maintain good nutrition habits before, during and after their runs. Some things to consider are your pre-workout meal, your glycemic index, eating during exercise and a high fat versus low fat diet.

Pre-workout Meal
Aerobic performance depends on glycogen stores in the body (carbohydrates); it’s what fuels our muscles. These stores become depleted during sleep and other periods of fasting. That is why eating a pre-workout meal is vital to fueling your run. The key components of the pre-workout meal are carbs and hydration. The best timing is 3 hours prior to working out to give time to digest, absorb and store energy. But, if you can’t allow 3 hours before exercise, it’s especially important to avoid foods high in fat, fiber and protein because they digest slowly and remain in the digestive tract longer.

Glycemic Index
The Glycemic index is a means to measure how carbohydrates affect blood sugar levels. Prior to exercising, it is best to eat carbohydrates with moderate to low glycemic index (i.e. whole wheat toast or oatmeal.) This is to avoid a rebound hypoglycemic (low blood sugar) event that can be caused by an insulin surge associated with high glycemic foods. However, eating foods with high glycemic index is not always bad. In fact, during the energy starved state of the body after intense exercise, the best way to replenish glycogen stores is with foods that have a higher glycemic index. Examples of high glycemic foods are a banana or white bread.

Eating During Exercise
High intensity aerobic exercise for 1 hour will deplete glycogen energy stores by about 55% and after 2 hours of vigorous exercise our glycogen stores are practically gone. Consuming about 60 grams of liquid or solid carbohydrates each hour of exercise has been shown to benefit performance for endurance events. Both our energy needs and fluid requirements can simply be met by drinking 1-2 oz per hour of a drink that contains between 4-8% concentration of carbohydrates (most sports drinks or gels).

High Fat vs. Low Fat Diet
Studies show that runners perform much better eating diets with carbohydrates. While recently there have been some very popular high protein and high fat diets, a balanced diet that includes carbohydrates will give you the best performance advantage.

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