Which of the following is NOT a cardiovascular benefit of exercise?

Increased muscle stiffness is the correct choice as it is not a cardiovascular benefit of exercise. When we engage in regular physical activity, we typically experience improved flexibility and muscle relaxation, rather than stiffness. Exercise is known to enhance cardiovascular health by improving the efficiency of the heart and blood vessels, which includes benefits like lowering cholesterol, reducing fat, and promoting better circulation. These responses help lower the risk of heart disease and stroke, while increased muscle stiffness does not contribute to cardiovascular well-being and may even indicate a lack of proper conditioning or stretching.