Final answer:
The fast glycolytic (FG) muscle fibers fatigue the most rapidly because they rely on anaerobic glycolysis for ATP production, which is less efficient and provides less energy than oxidative methods.
Step-by-step explanation:
The muscle fiber type that fatigues most rapidly is the fast glycolytic (FG) fiber. These muscle fibers are capable of fast contractions and primarily use anaerobic glycolysis to produce ATP. Consequently, they fatigue more quickly because they produce less ATP per cycle compared to fibers that use oxidative methods for generating ATP. FG fibers are designed for short, intense bursts of activity, such as sprinting or lifting heavy weights. In contrast, the slow oxidative (SO) fibers use aerobic metabolism and are more resistant to fatigue, which makes them suitable for endurance activities. Fast oxidative (FO) fibers also use aerobic respiration but can switch to anaerobic glycolysis, which makes them fatigue more quickly than SO, but not as quickly as FG fibers.