Part 1: Carbohydrates - Role of Carbohydrates in Exercise

Carbohydrates serve 4 important functions related to energy metabolism and exercise performance.

1) ENERGY SOURCES

Carbohydrates serve as an energy fuel especially during high-intensity exercise. Energy from catabolism of blood-borne glucose and muscle glycogen ultimately powers the muscle to contract and other forms of biological work.

Note that glycogen stores can be saturated. Once the stores reach maximum level, excess carbohydrates is converted to and stored as fat.

2) PROTEIN SPARER

Adequate carbohydrate intake helps preserve tissue protein. Protein is vital for tissue maintenance, repair, growth and metabolic functions. With glycogen depletion, the labile pool of amino acids may be used to make glucose. With extreme starvation or exercise resulting in extreme glycogen depletion, the lean body mass (muscles) may break down to provide energy.

3) METABOLIC PRIMER

Components of carbohydrate catabolism serve as substrate for fat oxidation. Insufficient carbohydrate breakdown (depletion etc). causes fat mobilization to exceeed fat oxidation. This incomplete fat breakdown leads to accumulation of ketone bodies. Ketone bodies leads to body acidity which can be harmful.

4) FUEL FOR CENTRAL NERVOUS SYSTEM

The brain uses blood glucose almost exclusively under normal conditions. Inadequacy of carbohydrate can lead to central nervous system fatigue with prolonged exercise.