Final answer:
Under anaerobic metabolism at peak muscle activity, there is an increase in glucose breakdown, leading to ATP production through glycolysis and lactic acid buildup.
Step-by-step explanation:
Under conditions of anaerobic metabolism, during peak levels of muscle activity, what typically occurs is an increase in glucose breakdown. This is because, under anaerobic conditions, the muscle's demand for ATP can exceed the oxygen supply, leading to the use of glycolysis for ATP production. Glycolysis, which occurs in the muscle cell's cytosol, can function without the presence of oxygen and breaks down glucose into pyruvate. Since the conditions do not provide enough oxygen for aerobic respiration, the pyruvate is then converted into lactic acid.
This process of breaking down glucose anaerobically provides some ATP, but not nearly as much as aerobic respiration would. It also increases the levels of lactic acid in the muscles, which may contribute to muscle fatigue. This buildup of lactic acid is a natural consequence of high-intensity exercise and is one of the factors that can lead to muscle fatigue.