Question

which of the following best explains the cardiovascular drift? during prolonged exercise there is a higher venous return to the heart and a increase in blood volume. therefore the heart rate increases to maintain cardiac output during prolonged exercise there is a lower venous return to the heart and a small decrease in blood volume due to sweating. therefore the heart rate increases to maintain cardiac output during prolonged exercise there is a lower venous return to the heart and a decrease in blood volume due to sweating. therefore the heart rate decreases to maintain cardiac output

Explanation:

Cardiovascular drift during prolonged exercise is characterized by a lower venous return to the heart due to sweating - induced blood volume decrease. To maintain cardiac output (the amount of blood pumped by the heart per minute), the heart rate increases. The first option is incorrect as it mentions higher venous return and increase in blood volume which is not the case. The third option is incorrect because the heart rate increases, not decreases, to maintain cardiac output.

Answer:

The second option: During prolonged exercise there is a lower venous return to the heart and a small decrease in blood volume due to sweating. Therefore the heart rate increases to maintain cardiac output.