Fiber types

Fiber types in the body primarily include two types: slow-twitch (Type I) and fast-twitch (Type II). Slow-twitch fibers are designed for endurance activities like walking or long-distance running; they are efficient at using oxygen to generate energy, making muscles resistant to fatigue. Fast-twitch fibers power quick, explosive movements such as sprinting or heavy lifting; they generate force quickly but tire faster because they rely more on anaerobic energy. Some muscles contain a mix of both types, allowing for a balance of endurance and strength depending on activity demands.