Exercise and Blood Pressure in Seniors

Summarized by Robert W. Griffith, MD
June 17, 2005

Introduction

It's possible that the usual lifestyle guidelines (plenty of exercise, eat right) don't apply equally to older people. In particular, they may not be very effective in dealing with high blood pressure. Scientists at the Johns Hopkins School of Medicine in Baltimore have investigated this, and published their findings in the Archive of Internal Medicine. Here's a summary.

What was done

The study, which was called the Senior Hypertension and Physical Exercise (SHAPE) study, was done in just over 100 patients aged 55 to 75 with mild high blood pressure. People with cardiovascular disease or serious medical illnesses, smokers, people with diabetes, and those who already exercised regularly were excluded. If they were taking blood pressure mediation, they stopped this for 2 weeks to see if they met the study requirements.

Selected at random, half the participants received 'usual care' (advice on exercise and diet) and acted as controls, while the rest underwent a 6-month supervised program of combined aerobic and resistance training. At baseline, their systolic blood pressure was between 130 and 159 mm Hg, or their diastolic pressure was between 85 and 99 mm Hg.¹

Blood pressure (BP) was measured at screening, baseline, and twice monthly for 6 months - at least one day after an exercise day. If subjects' blood pressure fell outside the accepted range (see above) on 2 consecutive occasions, they were withdrawn from the study. Effectiveness of aerobic and strength fitness was measured by peak oxygen uptake using a treadmill program, body weight, height, body mass index (BMI), fat mass, and percentage body fat. Aortic stiffness was measured by femoral pulse-wave velocity.

The exercising participants attended 3 sessions a week for 6 months; each session consisted of a warm-up period, 45 minutes of aerobics, and 2 sets of 10-15 repetitions of resistance training exercises.

What was found

The average age at baseline was 63 years. The average systolic BP was 140 mm Hg, and the average diastolic BP was 76 mm Hg. Those in the exercise group improved their aerobic and anaerobic fitness, increased their lean muscle mass, and reduced their general and abdominal obesity; their BMI decreased, on average, 0.7 units more than those in the usual care group. Men had a greater increase in upper and lower body and total muscle strength than women; and a greater reduction in abdominal fat than women.

After 6 months, both the exercisers and the 'usual care' controls reduced their systolic and diastolic BPs significantly, compared to baseline: systolic BP by 5.3 (exercisers) vs. 4.5 (controls) mm Hg, and diastolic BP by 3.7 (exercisers) vs. 1.5 (controls) mm Hg. The average diastolic BP reduction was greater in the exercisers than in the controls, but the reductions were about the same for systolic BP.

The degree of diastolic BP reduction was linked to changes in peak oxygen uptake, total muscle strength, body weight, percentage body fat, lean body mass, and abdominal fat. Systolic BP reduction, on the other hand, was only linked with decreased abdominal fat. There was no improvement in aortic stiffness in the exercisers or the 'usual care' controls.

What these results mean

It's generally accepted that exercise lowers blood pressure in hypertensive patients by improving body composition (less fat, more muscle), increasing cardiac performance, increasing heart output, and decreasing the resistance in the blood vessels. This particular study was done in older patients - their average age was 63 - and the improvement in blood pressure was confined to the diastolic BP.

An additional finding - a lack of improvement in aortic stiffness - supports the view that older people are resistant to exercise-induced reductions in systolic BP. Certainly, the changes in body composition (increased peak oxygen uptake, decreased BMI, decreased total body fat, and increased lean body mass) were the same as those reported with younger patients.

For many years the diastolic BP was always considered the more important measurement, and a degree of systolic hypertension would be tolerated. Not any more. Isolated systolic hypertension (where the systolic pressure is above 140 mm Hg and the diastolic is below 90 mm Hg) is now recognized as the most common form of high blood pressure in older people, and accounts for numerous cases of stroke, heart attack or myocardial infarction (MI), and heart failure. The present study suggests that exercise may not be the first thing to tackle in treating such people; salt restriction, weight loss, stopping smoking, decreased alcohol intake, and appropriate medication should be in the foreground.

Source

• Effect of exercise on blood pressure in older persons: a randomized controlled trial. KJ. Stewart, AC. Bacher, KL. Turner,  et al., Arch Intern Med., 2005, vol. 165, pp. 756--762

Footnotes
1. Blood pressure is recorded as a systolic number over a diastolic number. The systolic is the peak pressure achieved when the heart beats; the diastolic is the pressure when the heart relaxes between beats. Blood pressures less than 120/80 mm Hg (systolic/diastolic) are usually considered ideal.

Related Links
Which is More Important - the Upper or Lower BP Number?
Exercise: A Necessary Component in a Program for Vascular Health
High Blood Pressure: Are the Older Drugs Better?

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