- People store large amounts of body fat in the form of triglycerides within fat (adipose) tissue as well as within muscle fibers
(intramuscular triglycerides).When compared to carbohydrate stored as muscle glycogen, these fat stores are mobilized and oxidized
at relatively slow rates during exercise.
- As exercise progresses from low to moderate intensity, e.g., 25-65% VO2Max, the rate of fatty acid mobilization from adipose
tissue into blood plasma declines, whereas the rate of total fat oxidation increases due to a relatively large use of intramuscular
triglycerides. Intramuscular triglycerides also account for the characteristic increase in fat oxidation as a result of habitual
- Dietary carbohydrate intake has a large influence on fat mobilization and oxidation during exercise; when dietary carbohydrate
produces sufficient carbohydrate reserves in the body, carbohydrate becomes the preferred fuel during exercise. This is especially
important during intense exercise because only carbohydrate(not fat) can be mobilized and oxidized rapidly enough to
meet the energy requirements for intense muscular contractions.
Edward F. Coyle, Ph.D.
Professor, Department of Kinesiology and Health Education
The University of Texas at Austin
Member, GSSI Sports Medicine Review Board