Which of the following best defines "aerobic exercise"?

Aerobic exercise is best defined as a physical activity that increases heart rate and breathing while using large muscle groups. This type of exercise is characterized by sustained activity that relies on the cardiovascular system to supply sufficient oxygen to the working muscles, enabling them to perform continuously for an extended period. Examples of aerobic exercise include running, swimming, cycling, and dancing.

The focus on large muscle groups means that activities should engage major areas of the body, thereby enhancing overall cardiovascular fitness, endurance, and stamina. The increase in heart rate and breathing is essential for promoting increased oxygen intake, which fuels the muscles and contributes to improved aerobic capacity and efficiency.

Other definitions provided in the choices emphasize aspects that do not accurately represent aerobic exercise. For instance, the option describing physical activity that relies on short bursts of energy aligns more with anaerobic exercise, which is characterized by high-intensity efforts and limited oxygen supply. Similarly, the focus on low-intensity activities regarding flexibility and endurance does not capture the intensity and muscle engagement typical of aerobic activities. Lastly, exercise routines focused exclusively on resistance training do not fit the definition of aerobic exercise, as they primarily emphasize strength and do not significantly elevate heart rate in the same manner.