The biggest bang for the buck against hypertension
By Ralph Hall, MD
Emeritus Professor of Medicine
University of Missouri-Kansas City
How much, what kind, and how effective is exercise in treating hypertension? Hyper-tension is one of the most important risk factors for cardiovascular disease, stroke and end-stage kidney disease. The Joint National Committee Report on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends exercise as a significant component of the treatment of high blood pressure (BP).1
Hypertension affects more than 42 million people in the United States, and it’s the most common reason for outpatient visits.2 However, there are significant costs, difficulty with adherence, and often significant adverse events from the drugs used to treat hypertension. Therefore, nonpharmacologic approaches to treating hypertension are receiving more attention. But how effective are they?
In reviewing the literature covering exercise and hypertension, it is difficult to compare studies. There is great variation in the age, sex, and ethnicity, of the subjects and a marked difference in the intensity, duration, and whether the exercise was accompanied by weight loss and/or sodium restriction.
In their recent review, Hagberg and colleagues conclude that "approximately 75% of the subjects studied reduced systolic and diastolic BPs, which averaged 11 mm Hg and 8 mm Hg, respectively."3 They also noted that women may reduce their BP more than men and that middle-aged people seemed to obtain better benefits than young or older people.
A recent study is important in that it differentiates weight loss plus exercise from an exercise-only program, which Hagberg did not do. The study started with 133 sedentary, overweight men and women with unmedicated, mild hypertension and concludes that "although exercise alone was effective in reducing blood pressure, the addition of a behavior weight loss program enhanced this effect."
The subjects in the study included 59 men and 74 women, 23% of whom were black, starting at age 29. The average patient age was 47. BPs were obtained four times on three separate visits with the first measurement being discarded.
The last three pressure measurements were averaged and represented the clinic visit BP. The subjects also underwent ambulatory BPs monitoring from early morning until bedtime and had measurements taken of cardiac output and peripheral resistance.
The subjects then were randomized to three treatment groups. The groups were divided into an exercise-only group, a control group, and an exercise-plus-behavioral-weight management group. The subjects exercised three to four times per week at 70% to 85% of their heart rate reserve, as determined at the time of an initial treadmill test.
Participants in the weight-management group had an average 7.4/5.6 mm Hg reduction in their clinic systolic/diastolic BP as compared to a 4.4/ 4.3 mm Hg reduction in the exercise-only group. Those in the weight-management group also consumed less sodium during the experiment.
Fasting blood glucose and insulin levels were also lower in both exercise and the exercise-plus-diet groups following the study. The weight-loss-plus-exercise group had a statistically different improvement in treadmill time and peak oxygen consumption. Both groups responded to stress with less rise in their BP readings after their training.
Another recent study of diet and its effect on hypertension is worth noting.
Paul Conlin, MD, and fellow researchers at the endocrinology-hypertension division at Brigham and Women’s Hospital in Boston, studied a group of patients with hypertension with systolic BP of 140 mm Hg to 159 mm Hg and/or diastolic BP of 90 mm Hg to 95 mm Hg.
Participants were randomized to receive for eight weeks either the control diet; a diet rich in fruits and vegetables, but otherwise similar to control; or a combination diet rich in fruits, vegetables, and low-fat dairy products, including whole grains, fish, poultry, and nuts, and reduced in red meats, sweets, and sugar-containing beverages. Sodium intake and weight were held constant throughout the study.
The combination diet significantly reduced systolic BP 11.1 mm Hg and diastolic BP 5.5 mm Hg. The fruits and vegetable diet also reduced systolic BP 7.2 mm Hg and diastolic BP 2.8 mm Hg. Researchers concluded that the DASH diet (Dietary Approaches to Stop Hypertension) may be useful in achieving control of Stage one hypertension.
You could presume that reducing sodium and weight loss would have decreased BP even more in a few selected individuals. It would be interesting to see how much exercise, in addition to the DASH diet, will decrease the BP.
In the studies reviewed by Hagberg and colleagues, Asian and Pacific Island patients were more successful in reducing their BPs with exercise, more so than Caucasian patients. African-American patients also experienced significant reductions in their pressures with exercise training. They also note that in some studies there was a reduction in pathological left ventricular hypertrophy with exercise.
It’s obvious that other risk factors should be considered and treated in hypertensive patients. Endurance training improves lipid profiles especially if treated for longer periods of time.4 High-density lipoproteins often fail to change if treated for less than four to six months. That is in contrast to BP, which responds to exercise of moderate intensity and duration. In addition, high density lipoprotein responses to exercise are greatest in those with longer duration and higher intensity of exercise.
In the past, many physicians were satisfied with BPs of 140/90 mm Hg. The recent United Kingdom Prospective Diabetes studies on BPs in Type 2 diabetes demonstrated a marked drop in the incidence of both macrovascular and microvascular disease in patients whose BPs were lowered from 154/ 87mm Hg to 144/82 mm Hg.5 Data would indicate that more realistic goals are to reach BP levels of 130/80 mm Hg if possible.
My recommendation is to prescribe endurance exercise for five or six days per week and two to three days per week decrease the amount of endurance exercise and replace it with resistance training. The resistance training can be performed at 40% to 50% of maximum repetition capacity.
Resistance training is beneficial, too
This intensity, according to Hagberg’s studies, does not elevate BP and maintains strength. This is especially true for older patients. Resistance training also has the favorable effect on lipids that occur with endurance exercise. Diets are difficult to change, but the DASH diet would seem to have significant benefits, both in terms of hypertension and macrovascular disease.
As Hagberg and colleagues point out, "These results continue to support the recommendation that exercise training is an important initial or adjunctive step that is highly efficacious in the treatment of individuals with mild to moderate elevations in blood pressure."
The benefits of exercise in the prevention of cardiovascular disease are well-documented. Let’s make sure our patients benefit from this simple and inexpensive therapy — exercise and diet.
References
1. Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. The sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Arch Intern Med 1997; 157:2,413-2,446.
2. Burt VL, Curler JA, Higgins M, et al. Trends in the prevalence, awareness, treatment, and control of hypertension in the adult U.S. population: Data from the Health Examination Surveys, 1960-1991. Hypertension 1995; 26:60-69.
3. Hagberg JM, Park Jung-Park, Brown MD. The role of exercise training in the treatment of hypertension. Sports Med 2000; Sept 30(3):193-206.
4. Stefanick ML, Mackey S, Sheehan M, et al. Effects of diet and exercise in men and post-menopausal women with low levels of HDL cholesterol and high levels of LDL cholesterol. N Engl J Med 1998; 339:12-20.
5. UK Prospective Diabetes Study Group. Efficacy of Atenolol and Captopril in reducing risk of microvascular and macrovascular complications in Type 2 diabetes; UKPDS 39. BMJ 1998; 317:713-720.
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