During which type of exercise would the lactic acid typically begin to accumulate?

Lactic acid begins to accumulate primarily during high-intensity exercise, such as sprinting, due to the reliance on anaerobic metabolism. In these conditions, the body's demand for energy exceeds the oxygen supply available for aerobic respiration. When the muscles are contracting at a high rate, the body shifts to anaerobic pathways to rapidly produce energy, leading to the conversion of glucose into lactate (the form of lactic acid). This process occurs because anaerobic metabolism, while capable of generating ATP quickly, results in the production of lactic acid as a byproduct.

During low-intensity steady-state or moderate aerobic activities, oxygen is readily available, allowing the body to efficiently use aerobic metabolism, which does not produce lactic acid at significant levels. Similarly, while strength training can be intense, it generally involves short bursts of exertion followed by rest, allowing for recovery and oxygen replenishment, which limits lactic acid buildup compared to sustained high-intensity efforts like sprinting.