Which factor plays a crucial role in sustainable energy expenditure?

The correct answer emphasizes that both aerobic power and anaerobic capacity are significant factors in sustainable energy expenditure. Aerobic power, which refers to the maximum capacity of an individual's body to transport and utilize oxygen during exercise, is critical for prolonged physical activity. It determines how efficiently muscles can continuously produce energy through aerobic metabolism, which is vital during extended periods of exercise.

On the other hand, anaerobic capacity contributes to energy expenditure during high-intensity activities that last for shorter durations. While this form of energy production cannot be sustained for very long, individuals with a well-developed anaerobic capacity can perform short bursts of intense exercise effectively. This ability can enhance overall athletic performance and contribute to energy expenditure during exercise regimens that involve varying intensities.

Combining these two capacities allows for a more versatile and effective approach to physical activity, enabling the body to utilize different energy systems according to the demands of the exercise. Thus, both aerobic power and anaerobic capacity are indispensable for optimizing sustainable energy expenditure during various forms of exercise.