Human muscle cells are facultative anaerobes that perform lactic acid fermentation when oxygen is depleted from muscle tissues .During periods of high physical activity, such as a 100-meter sprint ,ATP is tepidly used from muscle contraction .The limited oxygen delivered to muscle cells becomes a problem ,and aerobic respiration is blocked .In anaerobic respiration, the ATP provide by rapid fermentation, temporary provides energy to maintain muscle function in the absence of oxygen until oxygen levels are restored . Yeast also performers cellular respiration in the obsence of oxygen , a process called alcoholic fermentation. what are two products of arcoholic fermentation?