Our blood pressure is constantly altering and it is extremely rare for an individual to have a blood pressure level  which is always the same no matter what. Almost everything we do will have an affect on our blood pressure which will move up and down as we go about our normal day to day business. Simple things such as walking the dog, walking, talking, drinking, standing up, watching television, sleeping, mowing the lawn, eating and almost anything else you can think of will alter your blood pressure. 

While the fact that your blood pressure is always changing is nothing more than a simple fact of life it can nonetheless create difficulties for doctors who need to be able to use blood pressure as a monitor of your general health. The problem is therefore to attempt to define a blood pressure level which we can consider to be a normal average and then to define limits below and above this figure which will represent the normal range of blood pressure change. A good point at which to start is to consider the pressure in the body's arteries as the heart is pumping freshly oxygenated blood throughout the body.

Our blood carries a mixture of nutrients and oxygen to all parts of the body through a series of blood vessels starting with the main aorta taking blood from the heart and ending in a multitude of tiny capillaries.

The first consideration therefore is exactly how high a pressure is required in the aorta as the blood leaves the heart for it to reach its destination in far flung parts of the body.

Next, the second consideration is how high a pressure is required in the capillaries for oxygen and nutrients to be transferred into the tissues of the body.

Careful study over many years shows that the best arterial pressure to deliver blood throughout the body and to enable the movement of oxygen and nutrients into the tissues of the body is 120 mm Hg. This figure represents the average blood pressure when the heart is pumping blood around the body and is frequently known as your systolic pressure.

As with most things in life though a pressure slightly above or below this figure is not going to make a lot of difference and your body will continue to function quite normally. However, if your blood pressure drops too low or rises too high then you will start to run into difficulty.

So exactly what are the lower and upper limits within which the average individual should be able to continue operating normally?

Here things become a little bit fuzzy and the answer varies from person to person. However generally speaking the upper limit for blood pressure in the majority of people will be in the region of 140 mg Hg and the lower limit will be in the region of 90 mg Hg.

Perhaps the most important starting point however is to establish the figure which is right for you and which takes into account such things as your age and general health together with your lifestyle. Having agreed this figure with your doctor it is then simply a matter of keeping an eye on you blood pressure.