What is the duration of activities for which oxidative (aerobic) metabolism is primarily utilized?

The correct choice reflects the primary role of oxidative (aerobic) metabolism as a source of energy during prolonged activities. Oxidative metabolism becomes the dominant energy pathway when exercise lasts longer than three minutes. This is because aerobic metabolism relies on the efficient utilization of oxygen to produce ATP (adenosine triphosphate) from carbohydrates and fats, which takes time to ramp up effectively in response to sustained activity.

In contrast, activities lasting less than three minutes typically rely more on anaerobic pathways, which provide energy quickly but are not as efficient as aerobic metabolism in terms of ATP yield and duration. For activities up to about 30 seconds, for example, the phosphagen system (using stored ATP and creatine phosphate) dominates, while the anaerobic glycolysis pathway is more prominent for efforts lasting between 30 seconds to a couple of minutes. However, once exercise extends beyond three minutes, the body transitions to utilizing aerobic pathways to meet the energy demands through oxygen-dependent processes.