What is the primary energy system used by fast-glycolytic muscle fibers?

Fast-glycolytic muscle fibers primarily rely on glycolysis for their energy supply. These fibers are designed for short bursts of high-intensity activity, such as sprinting or heavy lifting, where quick energy release is essential. Glycolysis is a metabolic pathway that breaks down glucose to produce energy rapidly, allowing these muscle fibers to perform well during anaerobic conditions, meaning they do not require oxygen for this process.

In contrast, aerobic metabolism involves the use of oxygen and is more suited to endurance activities, making it less relevant for fast-glycolytic fibers that focus on power and speed. Fat oxidation involves burning fats for energy, which is a slower process and not efficient for quick, intense efforts. Protein synthesis refers to the process of building proteins and does not directly provide energy for muscle contractions. Hence, glycolysis is the most appropriate choice for the primary energy system used by fast-glycolytic muscle fibers.