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After studying this chapter, the reader should be able to:

  • 7.1 Describe the pathway of glucose from food to fuel.

  • 7.2 Explain the rationale and effectiveness of carbohydrate loading.

  • 7.3 List the roles of protein in endurance and resistance training.

  • 7.4 Explain the rationale behind “fat loading” and why the method is not recommended.

  • 7.5 Recognize the major goals of pre-exercise, exercise, and post-exercise nutritional strategies.

  • 7.6 List several strategies to optimize pre-exercise, during exercise, and post-exercise nutrition.


  • carbohydrate loading Eating pattern that consists of increasing the amount of carbohydrates consumed in the days leading up to an athletic endurance event to maximize muscle and liver glycogen stores. Typically, activity levels are decreased during this time as well.

  • fat loading A strategy of progressively increasing percentage of fat intake to increase fatty acid oxidation and thus preserve glycogen stores for prolonged exercise.

  • gluconeogenesis The production of glucose from precursors such as proteins or fats in the liver.

  • glycemic index A measurement of the amount of increase in blood sugar after eating particular foods.

  • glycogen A polysaccharide that is a highly branched chain of glucose molecules. The chief carbohydrate storage material in animals formed and stored in the liver and muscle.

  • hyperglycemia An abnormally high level of glucose (sugar) in the blood (> 100 mg/dL fasting).

  • hyperinsulinemia An abnormally high level of insulin in the blood.

  • portal circulation Circulatory system that takes nutrients directly from the stomach, small intestine, colon, and spleen to the liver.

  • triacylglycerols Compound consisting of three fatty acids and one glycerol molecule.


Dennis Kimetto of Kenya holds the record for the fastest recorded marathon with a 2 hour, 2 minute, and 57 second finish at the 2014 Berlin Marathon—that’s about 4 minutes and 42 seconds per mile, or 12.8 miles per hour. These days, it’s not just elite runners who are triumphantly finishing 26.2-mile runs. Recreational athletes from teenagers to the elderly (the oldest finisher to date was 100 years old) repeatedly accomplish the feat. But the human body may not have been designed to run such long distances. Legend has it the first marathoner was the Greek soldier Pheidippides, who ran 25 miles to carry a message from the Battle of Marathon to Athens. He reportedly collapsed and died shortly after reaching his destination. While this story may be part myth, the point is important—without adequate preparation, including regular physical training and good nutrition and hydration, the body is susceptible to overheating and breaking down.

On the other hand, with appropriate training and nutrition, the body can be trained to perform at high levels under highly stressful conditions. For example, in 2010 a Belgian man ran a marathon for every day of the year—365 marathons in as many days. Regardless of whether an athlete is preparing for a 10K run, a century (100-mile) bike ride, or an Ironman distance triathlon (2.4-mile swim, 112-mile bike ride, ...

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