Question

During marathon, we sometimes get painful contractions of leg muscles due to the accumulation of one of the following in leg muscles. This is:

Options

• Carbon dioxide

• Alcohol

• Lactose

• Lactic acid

Answer 1

Lactic acid

During a marathon, most of the energy in our muscles is produced through aerobic respiration, while anaerobic respiration provides some extra energy needed under these conditions. The anaerobic respiration by the muscles brings about partial breakdown of glucose to form lactic acid. The accumulation of lactic acid in the muscles causes muscle cramps.