The question is incomplete. The complete question is:
Question: If the amount of oxygen required by your muscles during a workout exceeds your aerobic capacity, your muscle cells will
a. switch to anaerobic respiration and produce lactic acid
b. send a signal to the respiratory system to increase your breathing rate
c. stop getting energy until your breathing rate increases and more oxygen is delivered to your cells
d. increase their capacity to absorb oxygen
Answer:
a. switch to anaerobic respiration and produce lactic acid
Explanation:
Muscles require ATP to sustain their activities. Muscles obtain the ATP by performing aerobic cellular respiration. When the oxygen supply is not enough to keep with the demand, muscles perform lactic acid fermentation to ensure the continuous supply of ATP. Lactic acid fermentation includes the reduction of pyruvate into lactate and regeneration of NAD+ which is otherwise required for glycolysis. Glycolysis obtains 2 ATP per glucose molecule.
Therefore, lactic acid fermentation results in the build-up of lactate in muscles. Since lactic acid fermentation occurs in the absence of oxygen, it is also called anaerobic respiration.
