Positive Health Online

What is Blood Pressure?

Many people will be familiar with having their blood pressure taken. They may also be aware that it is important to be wary of high/low blood pressure. However, lots of people may not know what their reading means, and how important it is for your overall health and wellbeing.

Blood Pressure is the pressure of blood in your arteries, made up of two different numbers. One is the systolic pressure (the higher of the two numbers) - this is the pressure of blood during heartbeats. The other is the diastolic pressure (the second number), which gives the pressure between beats when the heart relaxes (BHF, 2009). An example of this would be 130/85 mmHg (millimetres of mercury). People's blood pressure will be different, depending on individual circumstances. Therefore it is important to have your blood pressure measured so you know what your normal reading is.

Category	Systolic mmHg	Diastolic mmHg
Low	100	60
Optimal	120	80
Normal	130	85
High Normal	130-139	85-89
Stage 1	140-159	90-99
Stage 2	160-179	100-109
Stage 3	180	110

Blood pressure varies constantly in response to various lifestyle factors such as fitness levels, stress and health of arteries. The body has specific responses to changes in blood pressure, which are lead by baroreceptors. The baroreceptors are located in blood vessels of the human body; their job is to detect the blood pressure and to send signals to the central nervous system (CNS). The CNS will then increase or decrease blood pressure accordingly. The baroreceptors are often more effective in reacting to low blood pressure rather than high blood pressure. A good example of this would be the way blood pressure reacts to the activity of sitting to standing; the blood pressure has to increase quickly to provide blood supply to the upper extremities and brain. An inefficiency of this leads to feelings of light-headedness. Blood pressure can vary throughout the day; hence it is essential that you take your blood pressure at the same time of day.

It is important for our blood pressure to be checked on at least a six to twelve month basis for over 45s (Blood Pressure Association, 2009). Often we are told our blood pressure is high without actually knowing what our 'numbers' are, and even when our health professionals tell us, we often don't remember our reading.

 

 

Primary High Blood Pressure (Hypertension)

High blood pressure is often asymptomatic, which means that high blood pressure (Hypertension) in the majority of cases can go undiagnosed. It is thought that up to 90% of the population with high blood pressure are unaware of their diagnosis (BACR, 2006). This is why high blood pressure is often called the 'silent killer'.

When blood pressure is higher than normal, the heart has to work harder in order to pump the blood into the circulation. If this is not treated over time this can lead to a thickened, enlarged and less efficient heart. Due to the increased size of the heart, it demands more oxygen compared to a healthy heart, thus further increasing blood pressure. It can also significantly increase the likelihood of a stroke or a heart attack.

It is often only people with severe hypertension, or a rapid rise in blood pressure that are likely to experience warning headaches, blurred vision, fits and blackouts (BUPA, 2002). If you have high blood pressure you are not alone; just over 3 in 10 men and just fewer than 3 in 10 women in the UK have high blood pressure (Health services, 2006).

Blood pressure increases with age and will often vary, minute-to-minute, day-to-day due to a number of different variables. A reading may show you have high blood pressure, but this may be due to feelings of anxiety and stress, especially so when being tested and worrying about being tested. Therefore it is important that high blood pressure is not diagnosed and medicated on the basis of one reading.

It is important when taking blood pressure readings that health care professionals use a blood pressure cuff that is appropriately sized. If the cuff is too large it can lead to an artificial low reading; too small and it will give you a falsely high reading. It is also good practice to take a reading from both arms.

Causes of Primary High Blood Pressure

It is not always easy to say exactly why a person has high blood pressure, but some common factors include:

• Being overweight- Reducing body fat, specifically central obesity, can significantly lower blood pressure;
• Having too much salt in your diet. Salt causes the body to retain fluid. Excess fluid causes the heart to work harder, which will increase blood pressure;
• Not eating enough fruit and vegetables - a lack of minerals and vitamins, particularly potassium, can cause the body to retain salt, leading to fluid retention as described above;
• A family history of high blood pressure. This can significantly increase the likelihood of developing high blood pressure;
• Being physically inactive - can cause inefficiency within the heart and arteries leading to a significant rise in blood pressure;
• Stress - can lead to heightened blood pressure by leaving the heart and body in a near constant state of arousal.

How Exercise can Help to Improve High BP

Myth: Exercise will make my blood pressure even higher
Truth:  Blood pressure will rise in the short term, as a response to the heart's need to meet the increased oxygen demands of the working muscles. However in the long term, exercise can help to decrease resting heart rate; this will help to reduce systolic blood pressure at various work intensities.

Typically a systolic blood pressure of 120mmHg can rise up to around 200mmHg during exercise at maximal exertion, in comparison to the diastolic blood pressure that hardly changes at all. This is our heart's prehistoric inbuilt response to being put under the stress of physical activity. Long term- regular physical activity has been shown to reduce systolic blood pressure by 10 mmHg and the diastolic by 8mmHg.

Myth: It is not safe to exercise with high blood pressure
Truth: Most people with moderate or high blood pressure are fine to increase their physical activity levels safely. However, if your blood pressure is very high your doctor may wish to bring your blood pressure down by using medication. It is safe to exercise with high blood pressure (140/90) unless it is very high (160/100). You should always consult your GP before commencing on a new exercise routine.

Always remember to include a warm up and a warm down into your routine. This can be a simple as walking round the house before setting out, or by starting a walk or a run slowly before building up to a moderate speed. Remember, your heart is very much like a car engine or bike cog; you would never start in fourth or fifth gear - it is the same principle with the heart and muscles. You will benefit from easing through the gears in preparation for exercise.

Myth: Any exercise is good for people with high blood pressure
Truth: Some, but not all exercise is good. Cardiovascular type activities e.g. walking, cycling, and swimming are particularly important for patients with high blood pressure, but it is still important to include some strength and flexibility based activity to gain the best health benefits.

People with high blood pressure should avoid heavy weight-based exercise. This is due to the smaller muscle mass in the upper limbs as opposed to the lower limbs. Consequently this means that static or dynamic work will put a greater demand on blood pressure. You should particularly avoid sustained over shoulder/head exercise where the blood pressure has to also fight against gravity to maintain the oxygen demand of the muscle.

With the exception of circuit based weight training, weight training has not been shown to specifically reduce blood pressure. So weight training does have a part to play in overall health and fitness, but not specifically in reducing overall blood pressure.

If you do decide to use weights, it is important not to hold your breath when exerting (Valsalva manoeuvre), as this will temporarily increase your blood pressure, putting an additional strain on your heart.

Myth: If you feel healthy you do not need to worry about blood pressure
Truth: Not only can physical activity help to reduce high blood pressure it can also help prevent it from developing in the first place. This may be of particular importance to people who may have a predisposition to high blood pressure through family history.

People tend to get the biggest reduction in blood pressure within the first ten weeks of regular physical activity, but the key is you need to remain active to maintain the benefits. Hence there is no value in exercising to bring your blood pressure down and then stopping once it has returned to a normal level.

Lack of physical activity can lead to a build up of a plaque like formation within the artery causing an overall narrowing. Due to the increased difficulty of the blood to flow through the arteries, this again will further increase the blood pressure.

Myth: You do not need to worry about your blood pressure if it's only slightly high.
Truth: You should still try and reduce your blood pressure even it is only slightly higher than normal. You need a certain amount of pressure within the arteries to keep the blood flowing. High blood pressure develops if the walls of the larger arteries lose their natural elasticity and became rigid, and the smaller blood vessels became narrower. By employing some simple strategies such as increased physical activity levels and reducing salt intake you may be able to reduce your blood pressure levels.

It is important to regularly check your blood pressure, so any increases can be regulated.

Myth: Jogging is the only exercise you can do to get fit
Truth: This isn't the only type of exercise. Stamina type activities such as walking, cycling and swimming are the ideal based activities. These types of activity will work on what is called your cardiovascular fitness. This form of fitness will help strengthen the heart, but by including activities such as walking uphill and Tai Chi you will also improve strength and flexibility.

In general you should try to increase your daily activity levels, by employing simple strategies such as using the stairs rather than the lift or going for a short walk on your lunch hour.

Myth: Low blood pressure (hypotension) is as bad as high blood pressure
Truth: Low blood pressure is often referred to as hypotension; a classic blood pressure reading would be 100/60 mmHg. People with low blood pressure tend to live longer than those with normal and high blood pressure, but do tend to suffer from side effects such as light headedness when standing to quickly (postural hypotension). Being aware that you have low blood pressure means that you can combat these side effects. For example moving slowly or by tapping the feet to improve circulation in preparation for activity.

In conclusion, there are many factors which can cause high blood pressure, but there are also many ways in which you can help combat it. There are huge benefits to exercise, and it is possible to do it safely and not only increase your fitness, but also help reduce high blood pressure. If you wish to find out anymore or ask any questions about blood pressure then please contact me.

References

BACR. British Association for Cardiac Rehabilitation Training Module. Human Kinetics Europe. Leeds. 2006.
Blood pressure association. www.bpassoc.org.uk  Date accessed September 2009
British Heart Foundation. Physical activity and high blood pressure (leaflet) British heart Foundation. London. March 2003.
British Heart Foundation.
www.bhf.org.uk/keeping_your_heart_healthy/preventing_heart_disease/blood_pressure.aspx Date accessed September 2009.
BUPA. http://hcd2.bupa.co.uk/fact_sheets/html/hypertension.html  Date accessed September 2009.
Department of Health. At Least Five a Week. Evidence on the Impact of Physical Activity and its Relationship to Health. A Report from the chief Medical Officer. Department of Health. London. 2004.