Medline ® Abstracts for References 1-6

PURPOSE: Physical activity has been associated with reduced blood pressure in observational epidemiologic studies and individual clinical trials. This meta-analysis of randomized, controlled trials was conducted to determine the effect of aerobic exercise on blood pressure.

DATA SOURCES: English-language articles published before September 2001.

STUDY SELECTION: 54 randomized, controlled trials (2419 participants) whose intervention and control groups differed only in aerobic exercise.

DATA EXTRACTION: Using a standardized protocol and data extraction form, three of the investigators independently abstracted data on study design, sample size, participant characteristics, type of intervention, follow-up duration, and treatment outcomes.

DATA SYNTHESIS: In a random-effects model, data from each trial were pooled and weighted by the inverse of the total variance. Aerobic exercise was associated with a significant reduction in mean systolic and diastolic blood pressure (-3.84 mm Hg [95% CI, -4.97 to -2.72 mm Hg]and -2.58 mm Hg [CI, -3.35 to -1.81 mm Hg], respectively). A reduction in blood pressure was associated with aerobic exercise in hypertensive participants and normotensive participants and in overweight participants and normal-weight participants.

CONCLUSIONS: Aerobic exercise reduces blood pressure in both hypertensive and normotensive persons. An increase in aerobic physical activity should be considered an important component of lifestyle modification for prevention and treatment of high blood pressure.

We measured physical fitness, assessed by maximal treadmill testing in 4,820 men and 1,219 women aged 20 to 65 years. Participants had no history of cardiovascular disease and were normotensive at baseline. We followed up these persons for one to 12 years (median, four years) for the development of hypertension. Multiple logistic risk analysis was used to estimate the independent contribution of physical fitness to risk of becoming hypertensive. After adjustment for sex, age, follow-up interval, baseline blood pressure, and baseline body-mass index, persons with low levels of physical fitness (72% of the group) had a relative risk of 1.52 for the development of hypertension when compared with highly fit persons. Risk of hypertension developing also increased substantially with increased baseline blood pressure.

The effects of a 16-week aerobic exercise program on blood pressure and plasma catecholamine levels were evaluated in 56 patients with baseline diastolic blood pressure of 90 to 140 mm Hg. The exercise group significantly improved their physical fitness, and reduced systolic and diastolic blood pressures, compared with controls. To evaluate the relationship between exercise, blood pressure, and plasma catecholamine values, the exercise group was further divided into hyperadrenergic and normoadrenergic subgroups. Reductions in systolic pressures were 6.3 mm Hg, 10.3 mm Hg, and 15.5 mm Hg for control, normoadrenergic, and hyperadrenergic groups, respectively. Diastolic changes were similar and also significant. Within the hyperadrenergic group, changes in blood pressures were associated with changes in values for plasma catecholamines following training. We conclude that an aerobic exercise program reduces blood pressure, which is at least partially mediated by changes in plasma catecholamine levels.

The long-term effect of exercise on blood-pressure (BP) was assessed in 13 untreated patients with essential hypertension. After a 6-week run-in period the levels of activity studied were sedentary, 45 min bicycling at 60-70% of maximum work capacity (Wmax) three times per week (3/week), and 45 min bicycling seven times per week (7/week), each for 4 weeks. The order differed between subjects in accordance with a Latin square. Supine BP, 48 h after each phase, averaged 148/99 mm Hg in the run-in and 143/96 mm Hg in the sedentary phase; it fell below values in the sedentary phase by 11/9 mm Hg with 3/week exercise, and by 16/11 mm Hg with 7/week exercise (both p less than 0.01). With increasing activity total peripheral resistance fell and the cardiac index rose. Plasma noradrenaline concentration fell below values in the sedentary phase by 21% and 33% after 3/week and 7/week exercise. Bodyweight and 24 h sodium excretion remained constant. Moderate regular exercise lowers BP and seems to be an important non-pharmacological method of treating hypertension.

We studied exercise training combined with the use of antihypertensive drugs and examined the following questions. (1) Are there additive antihypertensive benefits with exercise and drug therapy combined? (2) Does drug therapy limit exercise-induced lipid improvements? (3) Does exercise that includes weight training and walking/jogging affect the left ventricle? Fifty-two hypertensive men were randomly assigned, double-blind, to diltiazem hydrochloride, sustained release (360 mg daily), propranolol hydrochloride (240 mg daily), or placebo and exercised three times per week for 10 weeks. Baseline blood pressure (145/97 mm Hg) fell after training (131/84 mm Hg) in all groups. Exercise decreased total and low-density lipoprotein cholesterol levels in all groups. Increases in the levels of high-density lipoprotein cholesterol were similar in placebo and diltiazem groups, whereas the propranolol group changed in an opposite direction. In all groups, left ventricular mass increased with training, while diastolic function was unchanged. We conclude that (1) drug therapy provided no additive benefit to the antihypertensive effects of exercise, (2) propranolol limited improvements in high-density lipoprotein cholesterol, and (3) exercise did not adversely affect the left ventricle.

BACKGROUND: Although previous studies suggest that physical activity may reduce the risk of hypertension, the role of daily life activity in the development of hypertension remains unclear.

METHODS: The study population included 2548 Japanese male office workers aged 35 to 59 years, who were without hypertension (systolic blood pressure [SBP]<140 mm Hg, diastolic blood pressure [DBP]<90 mm Hg, and no medication for hypertension) and had no history of cardiovascular disease. Daily life energy expenditure was estimated by a 1-day activity record during an ordinary weekday at study entry. Blood pressures were measured at periodic annual health examinations over 7 successive years.

RESULTS: After controlling for potential predictors of hypertension (age, family history of hypertension, alcohol consumption, cigarette smoking, regular physical exercise at entry, and change in body mass index during the follow-up period), mean SBP and DBP in each follow-up year decreased as daily life energy expenditure increased. With additional adjustment for SBP at entry, the relative risk of hypertension (SBP>or =140 mm Hg and/or DBP>or =90 mm Hg or medication for hypertension) across quartiles of daily life energy expenditure (lowest to highest) were 1.00, 0.84, 0.75, and 0.54 (P<.001 for trend). Analyses by presence or absence of a risk factor demonstrated that the risk of hypertension was inversely related to daily life energy expenditure in men at either low or high risk of hypertension. Daily life energy expenditure was also associated with reduced risk of hypertension for subjects in all 3 categories of normotension: low normal, normal, and high normal.

CONCLUSIONS: Increased daily life activity is effective for the prevention of hypertension, and this benefit applies to men at either low or high risk of hypertension.