One of the first tests performed at the doctor's office or emergency room is to check a person's blood pressure. Blood pressure is one simple measure of overall or even immediate health and, when normal, reflects good cardiovascular function and blood circulation. Although a normal blood pressure doesn't rule out the possibility of disease, it's an important sign of good health.
What iIs Blood Pressure?
Blood pressure is a measure of how hard a person's heart has to work to pump blood through the body. Blood delivers oxygen to the cells, like the fuel that cycles through a car to keep it running. With each beat of the heart, blood is pushed through the blood vessels and exerts force, or pressure, on the walls of the arteries. If pressures are too high, over time they can damage the heart or blood vessels. If they're too low, inadequate oxygen is delivered to the body's cells.
Blood Pressure Terminology
Blood pressure is reported as a set of two numbers: systolic pressure and diastolic pressure, expressed as “mm Hg," or millimeters of mercury. When the blood pressure is said to be 120 over 80, or 120/80 mm Hg, the first number is the systolic pressure and the second the diastolic. Systolic pressure reflects the force exerted when a person's heart contracts and blood is ejected into the arteries. The higher this pressure, the more work the heart must perform with every beat. The lower diastolic pressure occurs when the heart rests between contractions.
Normal Blood Pressure
Doctors generally consider a blood pressure of 120/80 mm Hg or less to be normal and healthy. More attention is usually paid to the systolic pressure, but both numbers are important. Either a systolic pressure above 120 or diastolic pressure above 80 may be cause for concern if readings remain consistently high. High blood pressure, or hypertension, over time can lead to heart attack, stroke, kidney damage and vision problems. Low blood pressures are generally only of concern if they're below 90/60 mm Hg or accompanied by symptoms such as dizziness, fainting, clammy skin, shallow breathing or fatigue. Causes of low blood pressure include dehydration, serious infection, anemia and some heart conditions.
Factors Affecting Normal Blood Pressure
An individual's blood pressure can change for many reasons. Blood pressures are generally lower during sleep or at rest, and they increase with stress, anxiety or vigorous exercise. A single high blood pressure reading is generally of little concern, but consistently high readings should prompt medical evaluation. Blood pressure can be influenced by such factors as age, ethnicity, gender and physical fitness. Blood pressure tends to increase as people and their cardiovascular systems age. Men under age 55 are more likely to have high blood pressure than women, but the risk for women increases after menopause. Obesity, lack of physical activity, smoking and poor diet can all increase the risk of hypertension.
Maintaining Normal Blood Pressure
Lifestyle modifications can help an individual maintain a normal blood pressure. A diet low in salt that balances fruits, vegetables and whole grains usually is recommended. Regular exercise or physical activity and maintaining a healthy weight also can help. The American Heart Association suggests that managing stress, not smoking cigarettes and limiting alcohol consumption are all important steps to better blood pressure. If blood pressure readings remain high despite these steps, talk to a doctor about further treatment options.
- National Heart, Lung, and Blood Institute: What Is Blood Pressure?
- American Heart Association: Understanding Blood Pressure Readings
- American Heart Association: Why Blood Pressure Matters
- Blood Pressure UK: What Is Normal Blood Pressure?
- Neurology: Prehypertension and the Risk of Stroke -- A Meta-analysis
- National Heart, Lung, and Blood Institute: Categories for Blood Pressure Levels in Adults
- NIH SeniorHealth: What Is High Blood Pressure?
- Harvard Health Blog: New Guidelines Published for Managing High Blood Pressure
- MedlinePlus: Low Blood Pressure
- American Heart Association: Low Blood Pressure