Measuring Blood Pressure

When you measure a client’s blood pressure you are measuring two things - the maximum pressure (systolic) and the lowest pressure (diastolic) made by the beating of the heart.

The systolic pressure is the maximum pressure in an artery at the moment when the heart is beating and pumping blood through the body.

The diastolic pressure is the lowest pressure in an artery in the moments between beats when the heart is filling.

Both the systolic and diastolic pressure measurements are important - if either one is raised beyond normal levels, it means that your client has high blood pressure (known as hypertension).

How is blood pressure measured?

1.      To take a blood pressure reading, you need your client to be relaxed and comfortably seated, with their arm well supported on a bench or table. Their elbow should be resting at 90degrees

2.      A cuff that inflates is wrapped around your clients upper arm and kept in place with Velcro. A tube leads out of the cuff to a rubber bulb that is used to inflate the cuff.

3.      Another tube (sometimes its the same tube depending on the equipment) leads from the cuff to measureing unit (called a sphygmomanometer). This measuring unit is either a dial as shown on the right, or a column filled with mercury as shown above.  Whatever pressure is in the cuff is shown on the measuring unit. This is a sealed system – only air travels between the sphygmomanameter and the cuff.

4.      Air is blown into the cuff usually by squeezing the rubber bulb.  Enough air is blown into the cuff to increase the pressure to about 180mmHg (pressure is expressed in 'mmHg' which is millimetres of mercury).  The client will feel a tightening on their upper arm as the pressure increases.

5.      A stethoscope is placed over your client’s brachial artery underneath the cuff to enable you to listen to the arterial pulse while the air is slowly let out of the cuff.

6.      The systolic pressure is measured when you hear the first pulse at the brachial artery.

7.      This sound slowly becomes loader, then more distant and muffled and it finally disappears.

8.      The diastolic pressure is measured from the moment you are unable to hear the sound of the pulse at the brachial artery.

The following table indicates the established categories for normal and elevated blood pressure:

While statistically normal values for blood pressure could be computed for a given population, it needs to be remembered that, not only does blood pressure vary from person to person, it also varies in individuals from moment to moment. Additionally, since there's no guarantee the norm of the population in question should even be considered healthy, the relevance of such values would be questionable.

In children the observed normal ranges are lower; in the elderly, they are often higher, largely because of reduced flexibility of the arteries. Factors such as age, gender and race influence blood pressure values. Pressure also varies with exercise, emotional reactions, sleep, digestion and time of the day.

Levels above 120 but below 140 mmHg in systolic pressure, or above 80 but below 95 mmHg in diastolic pressure, are referred to as "pre-hypertensive" and often progress to hypertensive levels.  Studies reveal that there are fewer cardiovascular complications at, e.g., 115 mmHg systolic than 120, and in fact arterial pressure is a continuum with decreasing pathology associated with lower levels to well within the current “optimum range”.  Some data indicates that 115/75 mm Hg should be the gold standard.

Once arterial pressure rises above 115/75 mm Hg, the risk of cardiovascular disease begins to increase. Pre-hypertension is now widely considered to be a systolic pressure ranging from 120 to 139 or a diastolic pressure ranging from 80 to 89.  In the past, hypertension was only diagnosed if secondary signs of high arterial pressure were present, along with a prolonged high systolic pressure reading over several visits. In the U.S., this reactive stance has been soundly rejected in the light of recent evidence.

In the UK, mirroring abandoned earlier U.S. practice, nursing students continue to be taught that their patients’ readings should be considered ‘normal’ if in the range:

• Systolic: 110 - 140mmHg
• Diastolic: 70 - 90 mmHg

Clinical trials demonstrate that people who maintain arterial pressures at the low end of these pressure ranges have much better long term cardiovascular health. The principal medical debate is the aggressiveness and relative value of methods used to lower pressures into this range for those who don't maintain such pressure on their own. Elevations, more commonly seen in older people, though often considered normal, are associated with increased morbidity and mortality. The clear trend from double blind clinical trials has increasingly been that lower arterial pressure is found to result in less disease.

Regardless of the debate surrounding ‘optimal’ levels, accurately measuring your clients blood pressure is the most important safety measurement you make as a personal trainer.  So you must learn how to do this correctly to gather an true insight into the cardiovascular health of your clients.