Question

Fast-Glycolytic fibers are the largest and strongest of all the types of skeletal muscle. The units contract when muscle contracts are the Slow-Oxidative fibers. With the appropriate training, IIb fibers can be converted to IIa fibers or vice versa.

True or False?

Answer 1

Fast-glycolytic fibers are indeed the largest and strongest skeletal muscle fibers, using anaerobic glycolysis for quick, forceful contractions but fatigue quickly. Slow-oxidative fibers contract more slowly using aerobic respiration. Appropriately directed training can lead to conversion between Type IIb and Type IIa fibers.

Step-by-step explanation:

The statement about fast-glycolytic fibers (FG fibers) being the largest and strongest of all the types of skeletal muscle fibers is true. FG fibers use anaerobic glycolysis to produce ATP quickly, allowing them to produce high levels of tension. However, they fatigue quickly as well. The contraction units that contract when a muscle contracts slowly are slow-oxidative fibers (SO fibers), and these fibers use aerobic respiration to produce ATP.

With respect to training adaptations, it is true that with the appropriate training, Type IIb fibers can be converted to Type IIa fibers and vice versa. Type IIa fibers are also known as fast oxidative fibers and are rich in mitochondria and blood vessels, appearing red. These fibers can be trained to enhance their oxidative capacity or their glycolytic power, leading to a switch between subtypes IIa and IIb (also known as IIx or IId), which are the fastest muscle types in humans.