University Heart Journal Vol. 5, No. 1, January 2009

Role of as a Therapeutic Intervention for Hypertension Md. Shahidur Rahman 1, A.K.M . Salek 1 1Department of Physical Medicine and Rehabilitation Bangabandhu Sheikh Mujib Medical University Address for Communication Dr. Md. Shahidur Rahman Associate Professor Department of Physical Medicine and Rehabilitation Bangabandhu Sheikh Mujib Medical University, Dhaka E-mail : [email protected] Abstract Physical exercise is found to have positive health and well being of a person since time immemorial. Regular exercise has proved to normalize the elevated blood pressure of mild to moderate intensity by many studies. The blood pres - sure response to such exercise may also be used to screen normotensive persons for the risk of developing elevated blood pressure. For mild hypertension and life style changes such as weight loss, dietary changes such as salt restriction and cessation of smoking are probably better choices. In moderate to severe essential hypertension, exercise should be combined with life style changes and medication. The aim of this review study is to delineate the effect of exercise in the control of elevated blood pressure. Methods used were analysis of the published article col - lected from the internet and other sources. The specific aims were to emphasis the importance of exercise as therapeu - tic intervention for the control of hypertension.

Introduction into the active muscle capillaries, thus minimizing changes Increasing levels of physical activity, together with reduced in diastolic pressure. In turn, changes in mean arterial pres - sodium intake, weight loss, and limited alcohol consump - sure will also be minimized. These changes in resistance tion are therapeutic lifestyle changes known to effectively during exercise are impressive. The blood pressure response reduce blood pressure (1) . Data from the Coronary Artery to exercise differs between normotensive and hypertensive Risk Development in Young Adults ( CARDI A) study support people. In normotensive individuals, acute bouts of dynam - the fact that cardiovascular fitness is inversely related to the ic exercise result in a higher SBP (usually < 220mmHg) and development of hypertension, diabetes, the metabolic syn - a reduction in peripheral vascular resistance as described drome, and (2). Dynamic aerobic above. However, because of an elevated baseline level, the training, in particular, has been shown to lower convention - absolute level of SBP attained during dynamic exercise is al and daytime blood pressure readings among hypertensive usually higher in persons with hypertension (220mmHg or patients (3) . In general, exercise provides a substantial bene - more). In addition, DBP may not change, or may even fit for patients with both hypertension and cardiovascular slightly rise, during dynamic exercise, probably as a result disease ( CVD ) and reduces the 10-year cardiovascular risk of impaired endothelial function and increased sympathetic by 25% (4) . Two other advantages of exercise as a therapeu - outflow. Patients with hypertension exhibit an increase in tic intervention are its positive effect on multiple cardiovas - the total peripheral resistance and increases in myocardial (5). cular disease risk factors. Mild to moderate exercise has low oxygen consumption and impaired vasodilation risk and very few contraindications for most people. Immediately following an acute bout of exercise, a post exercise hypotension phenomenon has been recognized in Blood Pressure Response to Exercise both normotensive and hypertensive individuals. Exercise has been shown to have both an acute and a chron - This response may last up to 22 h after exercise and, due to ic effect on blood pressure ( BP ). The typical blood pressure the decrease in systemic vascular resistance, usually drops response to an acute bout of aerobic exercise is a gradual the arterial blood pressure by 5–7 mmHg. The reduction in increase in systolic blood pressure ( SBP ) and a gradual blood pressure after exercise can be sustained for up to 1–2 (6). decrease or no change in diastolic blood pressure ( DBP ). weeks, after three or more separate bouts of exercise Systolic and diastolic pressures at rest average around 125 Over time, these changes chronically translate into eccentric and 80 mmHg, respectively, with a mean pressure of about left ventricular hypertrophy with a preserved cardiac func - 95 mmHg. tion (7) . Therapeutic Intervention for Hypertension brought about by caused by the overload from exercise translates changes in the autonomic nervous system and hormonal into cardiomyocyte expansion, hypertrophic remodeling, influences. This affects systolic pressure more than diastolic and an increase in the contractile force per cell (8). This or means pressure. The reason for this is that during exercise homogenous, physiologic remodeling is beneficial, as there is a simultaneous decrease in resistance due to vasodi - opposed to the pathologic concentric hypertrophy related to latation of the arterioles supplying blood to the more meta - chronic hypertension, which involves apoptotic processes bolically active skeletal muscles. This means that more and the replacement of necrotic tissue by fibroblasts and blood will drain from the arteries through the arterioles and collagen (9). Role of Exercise as a Therapeutic Intervention for Hypertension Shahidur Rahman et a

A reduction in the cardiac output and/or a reduction in the multiple behavioral interventions including physical activi - peripheral vascular resistance are postulated as possible ty, weight loss, decreased sodium intake, decreased daily mechanisms for the antihypertensive effects of exercise intake of alcohol, and a diet high in fruits and vegetables training (10–12 ). Aerobic exercise is also associated with a and low in saturated and total fat ( DASH diet) (22) . Another decrease in plasma noradrenaline, which correlates with the meta-analysis of 54 randomized controlled trials (2419 reductions in SBP s and DBP s that are common among patients) evaluating the effect of aerobic exercise on blood hypertensive individuals with elevated resting cate - pressure reported an overall significant reduction in mean cholamine levels. SBP 3 to 8mmHg and mean DBP 2 to 6mmHg (23). BP was This reduction in levels of sympathetic activity may corre - significantly reduced even in trials whose participants did late with the reduction in cardiac output as well as in periph - not lose weight. Other factors such as daily emotional fluc - eral resistance (13) . At the endothelial level, the elevated tuations, stress, and degree of physical activity have also shear stress in the vessel walls, a product of the increased been implicated in the severity of hypertension and its blood flow to muscles during exercise, serves as a stimulus response to exercise. Regular aerobic exercise together with for nitric oxide release, thus leading to smooth muscle- weight loss has particularly proven to be beneficial in the mediated vasodilatation (14) . Reactive hyperemia, an index reduction of diastolic and mean arterial blood pressure dur - of the nitric oxide-related vasodilatation, improved with ing activities of daily living. In a study of 112 participants, long-term aerobic exercise in a study of Japanese patients the elevations of DBP and SBP, associated with the emo - with mild-to-moderate essential hypertension (15) . tional distress and physical activity variations during a typ - ical day, notably improved with 55 min of daily exercise (p There is also a depletion of whole blood and plasma vol - < 0.005) (24). umes, as well as sodium depletion, noted by a significant correlation between the changes in the sodium/potassium Exercise and Hypertension in the Elderly ratio and SBP (16). These changes were confirmed in a study where middle-aged men with essential hypertension sub - Progressive degeneration of the arterial media and increased jected to regular exercise experienced a significant reduc - collagen and calcium deposition results in stiffening of the (25). tion in blood pressure, a higher serum Na and K ratio, a arteries in the elderly, hypertensive population These higher cardiac index, and lower total peripheral resistance changes seem to be hastened by the effect of prolonged high (17). These findings help explain the theory that exercise blood pressure levels. Clinically, this is manifested by an reduces blood pressure more effectively in volume-depend - elevated SBP and has been implicated as a contributor to (26). ent hypertensive. cardiovascular morbidity and mortality However, mod - erate aerobic exercise training has failed to improve large- Clinical Evidence artery stiffness in patients with isolated systolic hyperten - sion (27). Nonetheless, a study involving elderly individuals Data from the First National Health and Nutrition with essential hypertension that were randomized to a low- Examination Survey (NHANES I) with 9791 study subjects or moderate-intensity training program found that low- revealed a favorable association between exercise and out - intensity exercise significantly reduces the systolic BP comes (all-cause and cardiovascular mortality) in hyperten - 7mmHg after 9 months of regular training (p < 0.05). Both sive individuals (p < 0.001 and p < 0.002, respectively), low- and moderate intensity exercise, however, reduced the when compared to normotensive and prehypertensive sub - DBP and mean BP by 9mmHg and 8 mmHg, respectively, jects (18). The chronic effects of regular exercise on individ - when compared with the control group of patients not exer - uals with hypertension are reflected by an average blood cising (28). An increase in the total body fat, particularly pressure reduction of 2.6–7.4mmHg (19). Thus, prescribing abdominal fat that is more prominent with aging, is also exercise should be a standard of practice, especially in directly related to the appearance of hypertension in this age patients with hypertension. group (29) . Data from multiple randomized controlled clinical trials Data obtained from the Senior Hypertension and Physical support the use of exercise for blood pressure reduction (20). Exercise ( SHAPE ) study revealed that after a 6-month ran - Despite this overwhelming evidence, some aspects remain domized controlled trial of aerobic and resistance training, undefined; one example is whether the reduction in blood (30). pressure is independent of weight reduction, body composi - exercisers failed to significantly reduce their SBP tion, and other modifiable risk factors. A meta-analysis of Aortic stiffening, as measured by aorto-femoral pulse-wave 44 randomized controlled clinical trials indicates that velocity, failed to improve with exercise as well; this would endurance exercise contributes to the control of blood pres - explain the resistance of systolic hypertension to improve sure in overweight as well as in lean subjects, although a with physical activity in the elderly. significant decrease in the BMI occurred in the obese popu - However, a meta-analysis involving 802 normotensive and lation only (21) . Although exercise seems to exert its benefit hypertensive patients older than 50 years demonstrated a independently from other modifiable factors, blood pressure significant reduction of 2mmHg in SBP (20). Younger adult control was most successful among individuals undergoing populations exhibit a better response to exercise. For

37 University Heart Journal Vol. 5, No. 1, January 2009 instance, a study involving postmenopausal women with an no further testing is advised. All hypertensive patients, how - average age of 55 years revealed a significant reduction in ever, must be carefully screened with a history and physical the systolic (from 142mmHg to 131 mmHg, 8%) and mean examination for the presence of secondary causes of hyper - arterial blood pressure (from 103mmHg to 98 mmHg, 5%) tension, the presence of risk factors, target-organ damage, after 24 weeks of regular in prehypertensive and and the presence of (19). stage I hypertensive patients. Systolic BP and mean arterial Exercise testing and monitoring is not necessary for prehy - BP remained constant in the control group throughout the 24 pertensive or stage one or two hypertensive who are less weeks. There was no significant change in resting DBP in than 50 years and have no CVD risk. Patients who are more either group across 24 weeks. The improvement was unre - than 50 years and have CVD or suspicion of CVD should be lated to body composition, diet, or fasting insulin levels (31) . started with low-impact activities such as walking, , and but this is better to have a exercise tolerance Prescription of Exercise for Patients with Hypertension test and interval ECG monitoring in case of chest pain. As a consensus, patients with hypertension should exercise Frequency of exercise should be 6–7 days/week with a start - most or all days of the week, for a minimum of 30 min of ing intensity of 20–30 min continuous aerobic activity at moderate aerobic exercise. Resistance training should serve comfortable pace. Then the individual is advised to maintain as an adjunct to an aerobic-based program (32). Moderate- aerobic program at up to 85% of maximum heart rate. For intensity exercise should be defined as one producing an patients who are overweight, weight reduction through diet elevation to 50–60% of the maximum heart rate and associ - modification is necessary. ated with 40–60% of the heart rate reserve or VO2 reserve. For endurance exercise training, it appears prudent to main - Conclusion tain exercise blood pressure values less than 220/105 Exercise and lifestyle modification as therapeutic interven - mmHg. Moderate-intensity exercise has been proven to be tion for the control of hypertension has proved efficacy as effective as vigorous activity in lowering blood pressure found in many controlled studies. Aerobic exercise training and is associated with fewer cardiovascular and muscu - (33). can be valuable in the treatment of mild to moderate essen - loskeletal adverse effects Hypertensive patients seem to tial hypertension. 35. It may cause a decrease in up to 10 mm maximally benefit from aerobic exercise involving large Hg in both systolic and diastolic blood pressure. 36 The muscle groups such as walking, , cycling, or blood pressure response to such exercise may also be used swimming. to screen normotensive persons for the risk of developing The prescription of exercise will vary according to the stage elevated blood pressure. 37 For mild hypertension aerobic of hypertension, the cardiovascular status in general, and the exercise and life style changes and risk factor modification patient’s age. These factors will determine the frequency, such as avoidance of sedentary habit, minimizing stressful intensity, duration, and type of exercise advised, and activity in office (to control white coat hypertension), whether exercise testing and monitoring is required. For weight reduction in case of , dietary changes such as instance, patients who are older than 50 years with docu - fatty diet and salt restriction and cessation of smoking are mented hypertension and suspected cardiovascular disease probably better choices. In moderate to severe essential will need evaluation and/or monitoring by a clinical exer - hypertension, exercise should be combined with life style cise physiologist and in these cases only light-to-moderate changes and medication. physical activity is recommended. Conversely, younger pre - hypertensive patients with no documented atherosclerotic References disease may engage in more strenuous activities and likely 1. Whelton PK, He J, Appel LJ. Primary Prevention of 34 do not require initial testing or monitoring Hypertension: Clinical and Advisory from the The evaluation of patients who will start to exercise depends National High Blood Pressure Education Program. JAMA. on the intensity of the anticipated activity and on the 2002; 288:1882–1888 patient’s cardiovascular risk factors. Peak or symptom-lim - 2. Carnethon M, Gidding S, Nehgme R. Cardiorespiratory ited exercise testing is warranted in patients with hyperten - Fitness in Young Adulthood and the Development of sion about to engage into hard physical activity or in those Cardiovascular Disease Risk Factors. JAMA . 2003; 290 (23) : individuals with cardiovascular disease. 3092–3100. Patients without cardiovascular disease, but with blood 3. Fagard R. The Role of Exercise in Blood Pressure Control: pressure more than 180/110mmHg, may benefit from exer - Supportive Evidence. J Hypertens. 1995; 13:1223–1227. cise testing before moderate activity but not before light activity. Commonly used criteria for discontinuation of 4. Hagberg JM, Park JJ, Brown MD. The Role of Exercise exercise testing include SBP and/or DBP values > Training in the Treatment of Hypertension: An Update. 250mmHg and 115 mmHg, respectively (19) . Conversely in Sports Med. 2000; 30(3):193–206. asymptomatic individuals with BP < 180/110mmHg who 5. Pickering T. Pathophysiology of Exercise Hypertension. are about to engage in light-to-moderate physical activity, Herz. 1987; 12 (2):119–124.

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