Describe the types of carbohydrates and fats used during inc

Describe the types of carbohydrates and fats used during increasing intensities of exercise and during prolonged exercise of moderate intensity.

Solution

Carbohydrates consumsed during exercise are obtained from muscle glycogen and blood glucose. Muscle glycogen and blood glucose are the source of carbohydrates during high and low intensity exercise respectively. Muscle glycogen supplies most of the carbohydrates in first hours of high-intensity exercise. On the other hand, liver glycogenolysis serves as main source of blood glucose during low-intensity exercise. It also serves as source of carbohydrates during long-duration exercise due to lowered level of muscle glycogen at that time. During prolonged, low-intensity exercise, fats serve as source of energy rather than carbohydrates. Intramuscular triglycerides and plasma FFA serve as fat source during exercise. Intramuscular triglycerides are mostly consumsed during higher intensity exercise while plasma FFA serves as fat source during low intensity exercise. Adipose tissue lipolysis converts the triglycerides to glycerol and FFA. The FFA enters beta oxidation and the resultant acetyl CoA molecules enter Kreb cycle to release the stored energy. Plasma FFA is important source of energy during long-duration exercise as muscle triglyceride levels decline.