Final answer:
Fast-twitch (type II) muscle fibers have a faster peak shortening velocity and faster rate of force production compared to slow-twitch (type I) fibers, due to their quicker ATP hydrolysis and rapid contraction capability supporting short, anaerobic bursts of activity.
Step-by-step explanation:
Compared with slow-twitch (type I) muscle fibers, fast-twitch (type II) fibers are known for having a faster peak shortening velocity and a faster rate of force production.
This difference arises because fast-twitch fibers hydrolyze ATP approximately twice as quickly as slow-twitch fibers, leading to quicker cross-bridge cycling and thereby a faster contraction speed. Additionally, fast-twitch fibers usually have a greater potential for increasing muscle mass and contribute more to muscle strength than slow-twitch fibers.
The metabolic pathways used also differ between these muscle fiber types. Slow-twitch fibers are dense in mitochondria and have a high capacity for oxygen which allows them to support endurance activities through aerobic metabolism. In contrast, fast-twitch fibers generate ATP quickly through anaerobic metabolism, such as glycolysis, but they fatigue more rapidly than slow-twitch fibers.
Fast-twitch fibers are especially prevalent in athletes who engage in activities requiring short bursts of power, such as sprinting and weightlifting, due to their ability to contract rapidly and powerfully.