Functional classification of skeletal muscle fibers

Fast glycolytic fibers

-Fast fibers, fast twitch fibers

-Most abundant

-Quick contractions and quick fatigue

-Less myoglobin

-Anaerobic cellular respiration

-Body builder

Slow oxidative fibers

-Slow twitch fibers

-Aerobic cellular respiration

-More myoglobin

-More capillary beds

-Resistant to fatigue

-Marathon runners

Fast oxidative-glycolytic fibers

-Intermediate fibers

-Hybrid of fast and slow

-Similar to fast but resistant to fatigue

-ATP produced by both aerobic and anaerobic cellular respiration

-Triathlete

True or false: Distribution of fast, slow, and intermediate fibers is genetically determined

True

-You CAN increase the numbers of specific fibers to a limit