(1) A form of cellular respiration that occurs when oxygen is absent or scarce.
(2) The process of generating energy by the oxidation of nutrients and using an external electron acceptor other than oxygen.
Obligate anaerobes strictly rely on anaerobic respiration to produce energy.
Humans, who are aerobes, carry out anaerobic respiration, especially when muscles perform strenuous exercise resulting in oxygen debt The cells then turn to anaerobic respiration to generate energy. Lactic acid and ATP are produced however the energy net gain is less compared with that in aerobic respiration.
Compare: aerobic respiration.
See also: cellular respiration.