Exercise as it relates to Disease/Hypertension: guidelines for exercise prescription

=HYPERTENSION: Guidelines for Exercise Prescription=

Hypertension: A life threatening condition
Cardiovascular disease (CVD) is currently one of the largest causes of death in Australia(3). A principal contributor to CVD, is Hypertension, also known as high blood pressure(5). Hypertension is also a considerable risk factor for stroke, coronary heart disease, kidney disease and heart failure(1).

Approximately 29% of Australians have hypertension(1). The 2004-2005 Australian National Health Survey data demonstrated that the prevalence of hypertension increases with age, as 14% of those aged 45–55 years reported the disease compared to 41% of those aged over 75 years. It is believed that as the average population age increases, so will these figures(5).

Currently the main form of treatment for patients with high blood pressure is the implementation of drug therapy and lifestyle modifications including dietary and physical activity(2).

The classification of blood pressure levels is found in the following table.

The relationship between Hypertension and Physical Activity
Epidemiologic studies demonstrate a strong relationship between physical inactivity and hypertension(1). For this reason, physical activity is recommended as a first line of intervention in the prevention, treatment and control of hypertension(1,2,5). According to the American College of Sports Medicine (ACSM)(4), the implementation of physical activity reduced the risk of developing hypertension with age by more than 30-50%. It is recommended for preventing and treating those with prehypertension and treating those with grade 1 and grade 2 hypertension.

The ACSM 2004 review(4) of the interaction between BP and exercise also suggests that there are a number of effects from physical activity. When in regard to endurance/aerobic exercise the following can be seen:


 * Acute/Short term effects: immediately after exercise there is an average reduction in BP of 5-7 mmHg, referred to as most as exercise hypotension. This affect regardless of exercise intensity may last up to 22 hours.


 * Chronic/Long term effects: with regular moderate endurance exercise lasting between 30 and 60 minutes individuals with hypertension not treated with drug therapy may reduce their baseline BP by 5-7 mmHg. Additionally individuals with normal baseline BP due to drug therapy may reduce BP further by up to 2.6 mmHg.

When in regard to resistance/strength training a favourable chronic effect on baseline BP is demonstrated, however it is important to note that these effects are lower than those demonstrated by endurance exercise(1).

Precautions

 * It is important to note that most patients with high-normal and grade 1 hypertension can safely participate in moderate exercise programs without thorough medical screening(1); however it is recommended to seek medical advice before starting any physical activity program(3).
 * For those with grade 2 and 3 hypertension and those over 50 years of age, a stress test is recommended to analyse the hearts response to exercise(1). Following this exercise should be prescribed by a certified clinical exercise physiologist(1,5).
 * When exercising monitor exertion and blood pressure levels closely(6). Take breaks when required.
 * A systolic BP higher than 220 mmHg and diastolic higher than 100 mmHg is considered abnormal when exercising(2).

Physical Activity suggestions

 * Type: Aerobic physical activity of a moderate intensity, incorporating large muscle groups is the recommended treatment strategy for all individuals with hypertension. Examples include walking, jogging, bike riding(1).
 * Intensity: Physical Activity of a moderate intensity is the optimal level for those with hypertension(1,2). This is considered as 50 – 60% of the individual’s maximum heart rate(1), easily estimated with the following equation, 220 - age.
 * Frequency: Physical activity should ideally be completed 5-7 days a week for at least 30-60 minutes. It is best to start and build up from 20 minutes of activity(1,2,4).
 * Other: Light resistance training may be beneficial and considered as an adjunct to aerobic physical activity(1), especially within ageing populations(5). However its effects are not as significant as aerobic physical activity. When resistance training is utilised individuals must not hold breath while lifting as this exacerbates the BP response to exercise(2).

Conclusion
Physical Activity prescription is considered as a first line prevention and treatment for hypertension. The benefits of physical activity are in many cases shown to be similar to those of the drug therapy. It is important to note that physical activity should be prescribed under the appropriate precautions for all individuals.

Recommended Reading
Exercising With Hypertension: Prescription for Health.

Heart Foundation Guide to management of hypertension

Hypertension: Exercise Recommendations for General Practitioners