The muscular tissue in the body of living organisms can be divided into three categories based on their characteristics. These are fast fibers, slow fibers and intermediate fibers.
Fast fibers refers to muscular tissue that can contract very fast once it is stimulated. They produce powerful contractions and most of the muscular tissue in our skeletal system is fast fiber. Fast fibers require a lot of energy which is extracted from glucose using anaerobic respiration. This does not allow fast fibers to perform tasks for a prolonged period of time without rest.
Slow fibers react slowly to stimulation and can contract for long durations without tiring. This is accomplished with a lot of capillaries present in the muscles that ensures an adequate supply of oxygen. Muscular tissue with more slow fibers is red in color whereas tissue with predominantly fast fibers is white in color.
Intermediate fibers have characteristics that lie between those of fast and slow fibers. They are able to contact at a relatively fast rate but contain a more extensive network of capillaries that allows access to more oxygen.