Accumulation of which of the following molecules in the muscles occurs as a result of vigorous exercise?

Step-by-step solution

As the muscles work harder during times of extreme exercises, the amount of oxygen needed to use during energy production runs short, and the muscle cells turn to another process called anaerobic metabolism. The product of this process of obtaining energy anaerobically is lactic acid. When the muscle cells continue to work anaerobically, lactic acid can build up in the muscles.