×
Type I muscle fibers
Slow-Twitch (Slow Oxidative) Fibers
Function: Endurance, sustained contraction over long periods.
×
Type IIa muscle fibers
Fast-Twitch (Fast Oxidative-Glycolytic) Fibers.
Function: Intermediate; supports both aerobic and anaerobic activity.
×
Type IIB muscle fibers
Examples are weightlifters and sprinters.
Type IIb (fast-twitch glycolytic) muscle fibers are most associated with early fatigue and are used predominantly during anaerobic, high-intensity activities