What is the effect of chronic exercise on resting heart rate?

Chronic exercise has a significant impact on resting heart rate, and the correct answer reflects a well-established physiological response to regular aerobic training. Engaging in consistent exercise, particularly aerobic activities such as running, swimming, or cycling, leads to adaptations in the cardiovascular system.

As the heart becomes more efficient through training, there is an increase in the stroke volume—the amount of blood the heart pumps with each beat. As a result, the heart does not need to beat as frequently to maintain adequate blood flow at rest, leading to a decrease in resting heart rate. This is often seen in trained athletes, who may exhibit resting heart rates that are significantly lower than those of sedentary individuals.

The physiological mechanisms at play include improved autonomic regulation, particularly increased parasympathetic (vagal) tone and decreased sympathetic activity, which together contribute to lower heart rates when at rest. Hence, the effect of chronic exercise is a clear decrease in resting heart rate, aligning perfectly with the selected answer.