During exercise, how does autonomic input change to heart rate?

During exercise, how does autonomic input change to heart rate?

• A. Parasympathetic increases, sympathetic decreases
• B. Parasympathetic decreases, sympathetic increases
• C. Both increase
• D. Both decrease

Answer: (B)

During exercise, the body needs more blood flow, so the heart rate rises by shifting autonomic input toward the sympathetic side and away from the parasympathetic side. The parasympathetic (vagal) brake is reduced, allowing the SA node to fire more quickly, while sympathetic activity increases, releasing noradrenaline and adrenaline that raise heart rate and contractility via beta-1 receptors. This combined effect speeds up the heart to meet the higher demand for oxygen and nutrients. So the best description is parasympathetic decreases and sympathetic increases.

During exercise, the body needs more blood flow, so the heart rate rises by shifting autonomic input toward the sympathetic side and away from the parasympathetic side. The parasympathetic (vagal) brake is reduced, allowing the SA node to fire more quickly, while sympathetic activity increases, releasing noradrenaline and adrenaline that raise heart rate and contractility via beta-1 receptors. This combined effect speeds up the heart to meet the higher demand for oxygen and nutrients. So the best description is parasympathetic decreases and sympathetic increases.