RESEARCH to PRACTICE
Exercise Guidance in Hypertension
Kerry J. Stewart, EdD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 28 - NO. 10 - OCTOBER 2000
About 50 million American adults have systolic blood pressure (BP) greater than 140 mm Hg and/or diastolic BP greater than 90 mm Hg (1). Hypertension is a leading risk factor for stroke, congestive heart failure, angina, renal failure, and myocardial infarction at all ages and in both sexes. Because of its adverse impact on health, high blood pressure is one of the related focus areas in the Healthy People 2010 report (section 12-9). The 1997 Joint National Committee (JNC 6) on prevention, detection, evaluation, and treatment of high blood pressure determined risk categories for hypertension and proposed methods for treatment (table 1) (2).
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TABLE 1. Useful Web Sites on Hypertension
National High Blood Pressure Education Program (NHBPEP)
Johns Hopkins Bayview Medical Center's exercise and hypertension slide presentation
The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure
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For BP control, the JNC 6 recommends exercise, along with dietary changes and weight management. In the JNC 6 model, risk group A has no risk factors, no target organ disease (TOD), and no clinical cardiovascular disease (CCD); risk group B has one or more risk factors not including diabetes and no TOD/CCD; and risk group C has TOD/CCD and/or diabetes, with or without other risk factors. Lifestyle changes are recommended as the initial therapy for risk groups A and B with high normal (130-139/85-89 mm Hg) or stage 1 hypertension (140-159/90-99 mm Hg). For risk group C or anyone with stage 2 (160-179/100-109 mm Hg) or stage 3 (>=180/>=110 mm Hg) hypertension, drug therapy along with lifestyle modification is advised. The Healthy People 2010 report identifies physical activity as a leading health indicator. Among the many health benefits of physical activity, the report recommends increased physical activity to help prevent high blood pressure and to reduce blood pressure in persons with elevated levels.
How Exercise Lowers Blood Pressure
Several studies report that moderate exercise can reduce both systolic and diastolic BP by 7 mm Hg (3,4). An NIH review (5) revealed that BP decreased in 70% of exercising subjects by an average of 10.5/8.6 mm Hg from an average starting level of 154/98 mm Hg. Exercise may lower BP through several possible mechanisms. One possibility is that after training exercise lowers cardiac output and peripheral vascular resistance, the primary determinants of essential hypertension at rest and during submaximal exercise. Other physiologic mechanisms include reducing levels of serum catecholamines and depressing plasma renin activity. Another possibility is that exercise training may decrease central fat deposition, a factor linked to hypertension.
Exercise Guidelines
Aerobic exercise. For mild hypertension, the American College of Sports Medicine (ACSM) (6) recommends 20 to 60 minutes of aerobic exercise 3 to 5 days per week, at 50% to 85% of maximal oxygen uptake. For patients with stage 2 or stage 3 hypertension, exercise should be at 40% to 70% of maximal oxygen uptake after patients begin pharmacologic therapy.
Resistance exercise. One concern about resistance training has been that it produces exaggerated BP responses. While an acute bout of resistance exercise does result in greater increases in BP compared with aerobic exercise, heart rate does not increase as much. As such, the rate-pressure product, which represents myocardial oxygen demand, may be lower with resistance versus aerobic exercise (7,8). A recent position paper of the American Heart Association (9) recommends mild-to-moderate resistance exercise, at 30% to 60% of maximal effort, for improving muscle strength and endurance, preventing and managing diverse chronic medical conditions, modifying coronary risk factors including hypertension, and enhancing psychological well-being.
Screening and exercise testing. The ACSM does not recommend exercise testing specifically to determine BP responses (6). However, if an exercise test is done for other purposes—for example, as part of a physical exam—BP responses to exercise provide an indication of risk stratification. Because hypertension often clusters with hyperlipidemia, hyperinsulinemia, and obesity, many hypertensive individuals will be candidates for exercise testing based on risk stratification guidelines.
Antihypertensive drugs and exercise. Medical management of hypertension is often complicated by concomitant hyperlipidemia, a sedentary lifestyle, hyperinsulinemia, glucose intolerance, reduced arterial compliance, sympathetic overactivity, and obesity. Unfortunately, some antihypertensive agents adversely affect other risk factors, and adherence to medication is often a problem. On the other hand, lifestyle changes improve multiple risk factors without any side effects. In some patients, exercise can reduce or eliminate the need for antihypertensive medication (8).
Future Directions
Exercise has an important role in the treatment and prevention of hypertension, and it can decrease BP. Nevertheless, a few issues regarding the effectiveness of exercise against hypertension need further study. First, most of the research on which exercise recommendations are based has involved younger subjects, whereas the prevalence of hypertension is greatest in middle-aged and older subjects. Therefore, whether the current recommendations for exercise are applicable to older patients with hypertension is yet to be fully determined. Second, while there is strong evidence supporting the efficacy of exercise for reducing blood pressure, motivating individuals at any age to increase their physical activity and maintain an active lifestyle remains a major public health challenge. The extent to which we can answer these questions and meet this challenge will help to further define the merit of an exercise prescription for preventing and treating hypertension.
References
- Sutherland J, Castle C, Friedman R: Hypertension: current management strategies. J Am Board Fam Pract 1994;7(3):202-217
- The sixth report of the Joint National Committee on prevention, detection, evaluation, and treatment of high blood pressure. Arch Intern Med 1997;157(21):2413-2446 [published erratum in Arch Intern Med 1998;158(6):573]
- Arroll B, Beaglehole R: Does physical activity lower blood pressure: a critical review of the clinical trials. J Clin Epidemiol 1992;45(5):439-447
- Kelley G, McClellan P: Antihypertensive effects of aerobic exercise: a brief meta-analytic review of randomized controlled trials. Am J Hypertens 1994;7(2):115-119 [published erratum in Am J Hypertens 1994;7(7 pt 1):677]
- Hagberg JM: Physical activity, physical fitness, and blood pressure: NIH Consensus Development Conference: Physical Activity and Cardiovascular Health. Bethesda, MD, Office of the Director National Institutes of Health, 1995, pp 69-71
- ACSM's Guidelines for Exercise Testing and Prescription, ed 6. Baltimore, Lippincott Williams & Wilkins, 2000, pp 206-208
- Stewart KJ, Effron MB, Valenti SA, et al: Effects of diltiazem or propranolol during exercise training of hypertensive men. Med Sci Sports Exerc 1990;22(2):171-177
- Kelemen MH, Effron MB, Valenti SA, et al: Exercise training combined with antihypertensive drug therapy: effects on lipids, blood pressure, and left ventricular mass. JAMA 1990;263(20):2766-2771
- Pollock ML, Franklin BA, Balady GJ, et al: Resistance exercise in individuals with and without cardiovascular disease: benefits, rationale, safety, and prescription: an advisory from the committee on exercise, rehabilitation, and prevention, Council on Clinical Cardiology, American Heart Association. Circulation 2000;101(7):828-833
Dr Stewart is associate professor of medicine and program director of Johns Hopkins Heart Health at the Johns Hopkins School of Medicine in Baltimore. Address correspondence to Kerry J. Stewart, EdD, Johns Hopkins Heart Health, Johns Hopkins Bayview Medical Center, 4940 Eastern Ave, Baltimore, MD 21224; e-mail to kstewart@mail.jhmi.edu.