Muscle Fiber Types
Type I
They have large volumes of myoglobin and so oxygen and high numbers of Mitochondria. Due to this fact they are very resistant to fatigue and are capable of producing repeated low-level contractions by producing large amounts of ATP through an aerobic metabolic cycle.
Type IIa
These fibers contain a large number of mitochondria and Myoglobin. They manufacture and split ATP at a fast rate by utilising both aerobic and anaerobic metabolism and so produce fast, strong muscle contractions.
Type IIb
they have a low level of myoglobin and also contain few mitochondria. They produce ATP at a slow rate by anaerobic metabolism and break it down very quickly.
