What is the primary action of the sympathetic nervous system during exercise?

The primary action of the sympathetic nervous system during exercise is to increase heart rate and contractility. During physical activity, the body requires more oxygen and nutrients to meet the heightened metabolic demands. The sympathetic nervous system responds by releasing norepinephrine, which stimulates the heart to beat faster and with greater force. This increase in heart rate (positive chronotropic effect) and contractility (positive inotropic effect) enhances cardiac output, ensuring that more blood—rich in oxygen and nutrients—is delivered to active muscles.

In addition to facilitating increased blood flow to working muscles, the sympathetic response also helps prepare the body for the stressor of exercise, enabling individuals to perform optimally. Various mechanisms, such as the redistribution of blood flow away from non-essential systems, further support this process, including reducing blood flow to the gut and skin, which is less critical during intense physical activity.