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Blood Pressure Basics by Joe Cannon, MS, CSCS

Just about all of us at one time or another has been to the doctor and had our blood pressure taken, that procedure where we get our arm wrapped in that Velcro-lined sheath and sit quietly while the doctor or nurse reads the results. Usually, those of us who are brave enough to ask how it went, get the reply, "its normal." Unfortunately, most people don't give any thought to blood pressure and just knowing its "normal" is enough for them. But if we were to think about it, what exactly is blood pressure? Why do we need it? What is "normal" blood pressure? What is abnormal blood pressure? Why do doctors check it periodically? For those of you who've always wondered about these and other important questions, read on and learn all about the basics of blood pressure.

Blood pressure is really nothing more than the pressure or force exerted on the walls of your blood vessels by your blood. The organ that is intricately involved with this pressure is your heart. As your heart beats, it forces blood through your blood vessels, propelling it to all the cells of your body. Because each heartbeat consists of a contraction phase (systole) and a relaxation phase (diastole), blood pressure is represented by two numbers: a larger number that represents the contraction of the heart (called the systolic blood pressure) and a smaller number, which represents the relaxation of the heart (called the diastolic blood pressure). Both numbers are usually written as a fraction. Therefore, your blood pressure is really a composite of two separate blood pressures representing the contraction and relaxation of the heart. For example, suppose someone has a blood pressure of 120/80. This fraction indicates that as the person's heart contracts, that person's systolic blood pressure is 120 and as their heart relaxes, their blood pressure (diastolic blood pressure) drops down to 80. Usually blood pressure numbers are expressed as millimeters of mercury (mm Hg). This convention is used because some blood pressure cuffs utilize mercury to facilitate the reading. If this seems confusing, think of it this way: if someone says you have a systolic blood pressure of 80 mm Hg, this means that the pressure inside your blood vessels is strong enough to push a column of mercury up 80 millimeters high.

What's Normal and High Blood Pressure?

Having said all this, you're probably wondering what is "normal" blood pressure and what is "abnormal." Normal blood pressured used to be referred to as 120/80 but that has since changed. A blood pressure of 120/80 is now referred to as pre-hypertension or pre high blood pressure. The reason for this change is based on the fact that there are statistics showing that that a 55 yr old person who has a blood pressure of 120/80 has a better than 90% chance of developing high blood pressure sometime during their life. Thus, the name pre-hypertension was adopted to call attention to this probability. Most medical experts recommend lifestyle changes for the person diagnosed with pre-hypertension. Modifications such as stopping smoking, exercise, reducing stress, eating less salt and consuming more fruits and vegetables are all examples of small changes that can lead to big drops in blood pressure. Having a blood pressure of less than 120/80 is termed "optimal." High blood pressure or hypertension is defined as having a consistent resting blood pressure greater than or equal to 140/90.

What Influences Blood Pressure?

Blood pressure can vary with gender, age, and even the time of day. For example, blood pressure is usually lowest just before awakening in the morning. So the thing to remember is, just because the doctor might get a high reading doesn't necessarily mean you have high blood pressure. It is generally accepted that at least two readings on separate occasions are required before one is diagnosed as having high blood pressure.

Are There Different Types of Hypertension?

Two different types of high blood pressure are usually recognized: essential hypertension (also called primary hypertension) and secondary hypertension. The difference between them is that with essential hypertension, the cause is unknown while with secondary hypertension, a known factor is causing it (for example kidney disease or atherosclerosis). If you are wondering which type you have, this tip might help: primary hypertension is responsible for about 90-95% all cases.

Exercise and Blood Pressure

Another thing that can alter your blood pressure is exercise. While it is true that blood pressure does rise during exercises, regular physical activity has been shown to lower both systolic and diastolic pressures. Interestingly, this effect of is most pronounced in those who have high blood pressure. The type of exercise that has been found to be safest in those with hypertension is light aerobic activities such as walking or light jogging, working up to 3 to 4 days a week and lasting for 30-60 minutes per exercise session. Because everybody is different, it is prudent to talk with your doctor before you begin exercising to lower your blood pressure. This is especially true if you are on high blood pressure medication because some of medications may interfere with your ability to exercise effectively. So, the bottom line is, your doctor knows you best and can make the best recommendations for your particular case.

About the Author: Joe Cannon, MS, CSCS, is an exercise physiologist, personal trainer, and health educator. He is the author several books including his latest, Nutritional Supplements, What Works and Why. A Review from A to Zinc and Beyond. For more information, or to contact him directly, visit his official website, www.Joe-Cannon.com