It is known that red muscle fibres in animals can work for longer periods of time continuously . How is this possible ?

Explanation

Generally muscles are of two types : (1) Red muscle (2) White muscle.
Red muscles can work for longer period because.
(i) They red Haemoglobin named Myoglobin so they appear red coloured.
Myoglobin accepts oxygen and stores in the form of oxymyoglobin. Oxymayoglobin release `O_(2)` during muscle contraction.
(ii) They have more mitochondria. So they can work till longer period .
(iii) They have less myofibrils network.
(iv) They can do aerobic respiration for longer period without storing lactic acid. So without tiring red muscles can contract for longer period .
(v) The rate of contraction is low for longer period. eg. back muscles in humans.