What type of muscle fiber is better suited for endurance activities such as long-distance running?
Answer
a. Neither type is suited
b. Both types are equally suited
c. Slow twitch fibers
d. Fast twitch fibers
The correct answer and explanation is:
The correct answer is c. Slow twitch fibers.
Slow twitch muscle fibers, also known as Type I fibers, are better suited for endurance activities such as long-distance running. These fibers have a higher concentration of mitochondria, the powerhouses of the cell, which allow them to produce energy through aerobic respiration. This means they rely on oxygen to produce energy, making them more efficient for prolonged activities. Slow twitch fibers are also more resistant to fatigue, which is a key trait for endurance sports where energy is expended over long periods of time.
These fibers contract more slowly than fast twitch fibers but are capable of sustaining contractions for longer durations without tiring quickly. They also have a rich supply of capillaries, which helps deliver oxygen to the muscle tissue during extended exertion. Because of these characteristics, slow twitch fibers are ideal for activities such as long-distance running, cycling, and swimming, where the body needs to maintain moderate effort over an extended period.
In contrast, fast twitch fibers (Type II fibers) are designed for short bursts of strength or speed. They generate power quickly and rely more on anaerobic metabolism (without oxygen), which leads to quicker fatigue. Fast twitch fibers are ideal for activities such as sprinting or weightlifting, where rapid and forceful contractions are needed, but the activity does not last long enough to require sustained energy.
Thus, for endurance sports like long-distance running, slow twitch fibers are the dominant muscle fiber type that enables athletes to perform for extended periods without tiring quickly.