What role does the heart play in sustaining aerobic activity?

The heart plays a crucial role in sustaining aerobic activity primarily by delivering oxygen-rich blood to the muscles. During aerobic exercise, such as running or cycling, the muscles require increased amounts of oxygen to produce the energy necessary for extended physical activity. The heart works in conjunction with the lungs to oxygenate the blood, which is then pumped through the circulatory system to the working muscles.

This delivery of oxygen-rich blood is vital for sustaining aerobic metabolism, which predominates during prolonged, moderate-intensity exercise. The efficiency of the heart’s pumping action affects how well the muscles can perform and endure aerobic activities. By supplying oxygen and nutrients while also aiding in the removal of carbon dioxide and lactic acid from the muscles, the heart supports endurance and overall athletic performance.

In contrast, the other options do not accurately reflect the heart's primary function during aerobic exercise. The heart does not directly increase blood volume; rather, it regulates the flow and pressure of blood in the existing volume. It does not pump oxygen-poor blood to the muscles as the primary function of the left side of the heart is to deliver oxygen-rich blood. While the heart does play a role in regulating body temperature through blood flow changes, this is not its primary role in sustaining aerobic activity