How Much Do You Know About Low Blood Pressure?

Normal blood pressure in adults is less than 120/80 mm Hg. The exact level that marks low blood pressure differs from person to person. But the definition of low pressure is a blood pressure below 90/60, according to the National Heart, Lung and Blood Institute (NHLBI). The American Heart Association (AHA) goes further. The AHA says that low blood pressure is blood pressure that is low enough to cause symptoms of lightheadedness or fainting. The body uses several mechanisms to regulate blood pressure. It can:

• Expand or narrow (constrict) blood vessels
• Change the amount of blood pumped from the heart
• Change the amount of blood pumped through blood vessels

These mechanisms help blood pressure return to normal after changes brought on by eating, exercise, sleep, or position. Ongoing (chronic) low pressure may be a sign of disease. But it also can mean good physical conditioning. Athletes often have low blood pressure.