Related Experiment Video
Updated: Jun 27, 2026

Measurement of Basal and Forskolin-stimulated Lipolysis in Inguinal Adipose Fat Pads
Published on: July 21, 2017
Physiological factors that regulate the use of endogenous fat and carbohydrate fuels during endurance exercise
Bettina Mittendorfer1, Samuel Klein
1Department of Internal Medicine and Center for Human Nutrition, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8031, St Louis, MO 63110, USA.
Abstract:
Exercise causes a dramatic increase in energy requirements because of the metabolic needs of working muscles. Exercise-dependent factors regulate fuel use. Absolute exercise intensity determines the exercise-induced increase in energy demands, whereas exercise intensity relative to an individual's maximal aerobic capacity (VO2max) determines the proportional contribution of different fuel sources (i.e. plasma glucose, plasma fatty acids, muscle glycogen and intramuscular triacylglycerols). Endurance training increases aerobic capacity in muscle and the oxidation of fat during exercise. In addition, exercise-independent factors, such as diet composition, sex, age, and body composition also influence substrate use during exercise. The present review discusses the regulation of substrate use during exercise in human subjects, with a focus on the role of exercise-independent factors.
Related Concept Videos
Metabolic States of the Body: Fasting and Starvation
Muscle Recovery and Fatigue
Glucose Homeostasis: Regulation of Blood Glucose
During fasting, when blood glucose levels are low, the pancreas secretes glucagon. it...
Fats as Energy Storage Molecules
Fats as Energy Storage Molecules
Metabolic States of the Body: The Postabsorptive State
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...
