Completing three minutes of moderate intensity exercise would use fuel primarily from which metabolic pathway?

The correct choice for the fuel source used during three minutes of moderate intensity exercise is aerobic metabolism, specifically from carbohydrates, which is utilized predominantly at this level of activity. During moderate exercise lasting several minutes, the body primarily relies on aerobic pathways to generate the energy required for muscular activity.

Aerobic metabolism is efficient and provides a sustained energy supply through the oxidative phosphorylation of glucose, which is derived from carbohydrates. As exercise intensity increases, the body shifts its reliance from stored creatine phosphate and anaerobic pathways, which are more suitable for shorter, high-intensity efforts.

While lipids serve as an energy source during prolonged low-intensity activities, they do not provide energy as rapidly as carbohydrates in the moderate intensity range, making it less favorable for a three-minute duration. Proteins are generally not a primary fuel source during exercise unless the glycogen stores are severely depleted.

In summary, during three minutes of moderate intensity exercise, the body predominantly uses aerobic metabolism of carbohydrates, which allows for an efficient and sustained energy supply needed for that duration and intensity of exercise.