Hypertension is the clinical term used to describe a high blood pressure (BP) of 140/90mmHg or higher (National Institutes of Health (NIH, 1997). It is such a health risk that the World Health Organisation (WHO) and International Society of Hypertension (ISH) claim that “one of the biggest challenges facing public health authorities and medical practitioners is the control of hypertension worldwide”. 

Worldwide, high blood pressure affects 1 billion people (NIH, 2003) and is estimated to cause 7.1 million deaths; 13% of the total deaths (WHO, 2002). For those suffering with hypertension (systolic BP ≥ 140mmHg and/or diastolic BP ≥ 90mmHg) there are increased risks of coronary artery disease, strokes, renal disease, and all-cause mortality (Gordon, 1997).

Hypertension is almost always asymptomatic i.e. without symptoms (WHO, 2002), thus it is sometimes described as a ‘silent killer’ and is normally only detected by the use of a stethoscope and sphygmomanometer.  Only people with severe hypertension or a rapid rise in BP are likely to experience warning headaches, blurred or impaired vision, fits or black-outs (BUPA, 2002). 

Elevated BP levels can produce a variety of structural changes in the arteries that supply blood to the brain, heart, kidneys and elsewhere. Yet 7 out of every 10 people with hypertension are not being treated adequately, according to the WHO and ISH (Chalmers, 1999).

Pathophysiology

The American College of Sports Medicine (Franklin, 2000) states that hypertension may be categorised as primary (cause unknown) or secondary (caused by identifiable disorders).

Primary hypertension:

95% of people with high BP have what’s called primary or essential hypertension. This means that there’s no single clear cause of it (BUPA, 2002). This would seem to be simply related to genetic predisposition, with a positive family history being a large risk factor. Lifestyle factors, such as obesity, high alcohol intake, high salt intake and stress all play a part as well. These factors all affect the process of atherosclerosis in which arteries become progressively narrower (increasing peripheral resistance), reducing their ability to dilate and increasing BP. The heart experiences increased resistance and has to work harder (increased cardiac output). Increasing peripheral resistance and/or cardiac output will increase BP (McArdle et al, 1996).

Secondary hypertension:

The other 5% of people with high BP have what’s known as secondary hypertension (BUPA, 2002). This means it can be linked to a recognised, and possibly reversible, cause and may actually be a symptom of an underlying problem or disease. Secondary causes of hypertension include kidney disease, adrenal gland disease, narrowing of the aorta (Gordon, 1997). Medications, such as oral contraceptive or steroids, may also elevate BP (BUPA, 2002).

Causes of Elevated Blood Pressure

Chronic pressure overload and microvascular damage are the ultimate causes of an increase in blood pressure. There are 3 elements that cause this increase:

• cardiac output
• peripheral resistance
• blood volume

Haemodynamic Response to Exercise

The heart, blood and vessels undergo changes in relation to increased activity and exercise. These changes can be affected in hypertensive individuals. The differences in haemodynamic responses between a healthy and hypertensive individual are highlighted in the table below.

A hypertensive individual also has increased myocardial oxygen demand placing a greater strain on the heart. In the long term left ventricular walls stiffen, lose elasticity and as a result reduce contractility and performance.

Classification of Hypertension

Exercise Recommendations

It is necessary to understand that exercise recommendations are dependent upon the level of hypertension. ‘High normal’ and ‘Stage 1’ are provided with different recommendations to ‘Stage 2 and 3’. ‘High Normal’ and ‘Stage 1’ are only advised to make lifestyle changes such as appropriate exercise, improving diet, reducing weight, moderating alcohol, stop smoking and decreasing stress. Whilst ‘Stage 2 and 3’ are advised to introduce lifestyle changes and take medication.

Aerobic exercise recommendation:

Aerobic physical activity using large muscle groups in a rhythmical fashion is probably the most beneficial form of exercise. Systolic BP and diastolic BP can be lowered by approximately 6-10 mmHg with regular aerobic exercise for many previously sedentary men and women, regardless of age (McArdle et al, 1996). Obvious activities would be walking, jogging, cycling, or cross trainers. Exercise training at somewhat lower intensities (e.g. 40-70% VO2 max) appears to lower BP as much as, if not more than, exercise at higher intensities (Gordon, 1997). ACSM recommendations for hypertension (Stewart, 2000) are:

Roberts (1997), also makes the following recommendation:

• employ a longer warm up and cool down

Resistance training exercise recommendations:

With the exception of circuit weight training (Harris, 1987), chronic strength/resistance training has not consistently been shown to lower resting blood pressure. Therefore, whilst resistance training can have many benefits for such groups, it is not recommended on its own as a means of decreasing blood pressure.

• avoid performing ‘valsalva manoeuvres’ and promote normal breathing patterns

Flexibility recommendations:

Follow the usual recommendations for flexibility training (adapted from ACSM, 2000):

• ensure the client breathes normally

Special exercise recommendations:

Roberts (1997), makes the following recommendations regarding strength training programmes and hypertensives:

• avoid isometric or power work
• avoid breath holding (Valsalva manoeuvre)

Additional recommendations to limit any increase in BP would be:

• do not go to concentric failure
• reduce the load when working above the shoulders in ‘High normal’ and ‘Stage 1’
• avoid overhead work completely in ‘Stage 2 and 3’
• avoid incline sit-up or decline bench exercises

DO NOT EXERCISE IF:

• resting systolic BP >200mmHg or diastolic BP >115 mmHg (Gordon, 1997).

Additional Lifestyle Recommendations

The treatment of hypertension is complex, and may require medication if severe, to decrease peripheral resistance or cardiac output. In the case of mild hypertension, lifestyle modifications such as cessation of smoking or increased activity may suffice. This would obviously be preferable to drug treatment, but in some instances medication is unavoidable. 

According to the guidelines (Chalmers, 1999):

“Smoking cessation is the single most powerful lifestyle measure for the prevention of both cardiovascular and non-cardiovascular diseases in hypertensive patients,” and excess body fat is described as “the most important factor predisposing to hypertension”.

The NIH (2003) has developed the following lifestyle measures for reducing hypertension:

The DASH (Dietary Approaches to Stop Hypertension), seeks to maintain adequate potassium, calcium and magnesium intake, and reduce saturated and total fat intake.

In addition to these recommendations, we can advise hypertensives to stop smoking, which will reduce overall cardiovascular risk (NIH, 2003). Learning to cope better with stress would also be recommended. 

Medications 

It should be noted that in some people with prehypertension or stage 1 hypertension, exercise can be just as effective as high blood pressure medications. Indeed, some exercisers have subsequently reduced their medication dosage while others have safely gone off it altogether (ACSM, 93). These guidelines cover four classes of hypertensive drugs (diuretics, beta-blockers, ACE inhibitors, calcium channel blockers). It must be remembered that anti-hypertensive medications alter the biochemistry of the body and may alter the client’s response to, or ability to perform, exercise. Normally only prescribed for ‘stage 2’ and ‘stage 3’ hypertensive clients.

Adapted from MacKnight 1999

Hypotension

In order to function properly, the brain must be supplied with blood at an adequate pressure.  If the pressure falls, symptoms may be experienced such as:

• tiredness
• general weakness 
• light-headedness and fainting (syncope)
• blurred vision 
• dizziness 
• palpitations 
• confusion 
• nausea

(NHS, 2002)

People with hypotension (<100 / 60 mmHg) are more liable to experience these symptoms when rising quickly or standing still after a training session (postural or orthostatic hypotension). Hypotension is not normally harmful, and only in rare instances are drugs prescribed. 

There can be a number of causes (NHS, 2002): 

• adverse effect of certain drugs, including diuretics, anaesthetics, nitrates, calcium blockers, certain types of antidepressant drugs and drugs for the treatment of high blood pressure 
• dehydration (heavy sweating, loss of blood, severe diarrhoea) 
• fainting 
• shock due to internal bleeding, severe infection or heart failure, heart attack or an irregular heartbeat 
• anaphylaxis (a severe allergic response) 
• diabetic neuropathy or peripheral neuropathies 
• it can also be related to pregnancy

Exercise prescription:

Exercise is the best course of treatment for hypotension and ensuring adequate levels of hydration may also be important. Hypotensives should always warm up and cool down adequately to avoid blood pooling and fainting.

References

American College of Sports Medicine (1993). Physical activity, physical fitness and hypertension.  Medicine and Science in Sports and Exercise, 25, i-x.

BUPA (2002) High blood pressure, http://www.bupa.co.uk/fact_sheets/html/hypertension.html

Chalmers J. (1999). World health organisation-international society of hypertension. Guidelines for the management of hypertension. Journal of Hypertension., 17 (2), 151-183.

Franklin, B. A. (Ed.) (2000) ACSM’s Guidelines for Exercise Testing and Prescription. 6^th Edition, Williams and Wilkins.

Gordon, N. F. (1997). Hypertension. In ACSM’s Exercise Management for Persons with Chronic Diseases and Disabilities (J. L. Durstine, Ed.) pp. 59-63, Human Kinetics.

Harris, K. A. and Holly, R. G. (1987). Physiological responses to circuit weight training in borderline hypertensive subjects. Medicine and Science in Sports and Exercise, 19, 246-252.

McArdle, W. D., Katch, F. I. and Katch, V. L. (1996). Exercise Physiology. 4^th Edition, Williams and Wilkins.

National Institutes of Health, National Heart, Lung and Blood Institute (1997) Sixth report of the Joint Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNCVI), Public Health Service, NIH Publication No. 98-4080.

National Institutes of Health, National Heart, Lung and Blood Institute (2003) Seventh Report of the Joint Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), Public Health Service, NIH Publication No. 03-5233.

NHS (2002). Hypotension.  http://www.nhsdirect.nhs.uk

Roberts, S. (1997). Special Populations and Health Concerns. In ACE Personal Trainer Manual (R. T. Cotton, Ed.). Ace Publishing.(Reebok University Press.), pp. 328-329.

World Health Organisation (2002) The World Health Report 2002. chapter 4., p5.http://www.who.int/whr/2002/chapter4/en/index4.html

MacKnight, J M, (1999). Hypertension in Athletes and Active Patients, The Physician and Sports Medicine

Stewart, K J, (2000). Exercise Guidance in Hypertension, The Physician and Sports Medicine