Numerous health benefits are derived from regular exercise, such as a reduced incidence of cardiovascular and cerebrovascular disease. The level of intensity required to lower blood pressure is unclear, however. Moderate-intensity activity appears to be as useful as high-intensity activity in lowering blood pressure. Young and colleagues conducted this randomized clinical trial to determine whether 12 weeks of moderate-intensity aerobic exercise or t'ai chi could help lower blood pressure in a group of sedentary older patients.
Patients were included in the study if they were between 60 and 80 years of age and had an average systolic blood pressure between 130 and 159 mm Hg and a diastolic pressure of 95 mm Hg or less. Patients were excluded if they engaged in more than 10 minutes of vigorous activity per week or were taking antihypertensive medication or insulin. Patients were also excluded if they had had a recent myocardial infarction or stroke, or if they had angina, heart failure or exercise-induced asthma. After two screening visits, patients were randomized to the t'ai chi group or the aerobic exercise group. The t'ai chi group was instructed in the physical movements of t'ai chi (with minimal emphasis on the meditation and philosophic aspects), which consists of 13 sequential movements that are performed in a slow, continuous manner. These relaxed movements served to minimize heart rate increases. Patients randomized to the aerobic activity group were instructed to exercise at 40 to 60 percent of their heart rate reserve (i.e., estimated maximal heart rate minus resting pulse rate). All participants had group exercise sessions of one hour twice a week and individual exercise sessions (for 30 to 45 minutes) two to three alternate days per week. At the biweekly follow-up visits, blood pressure measurements were recorded.
Each group consisted of 31 participants, most of whom (93 percent) had a body mass index of more than 25. Ninety-seven percent of participants completed the study and the follow-up visits. Both groups showed significant decreases in both systolic and diastolic blood pressure levels. Most of the decreases in blood pressure occurred during the initial stages of the intervention, but less marked decreases continued to occur over the course of the 12-week study. Average heart rate during the exercise activity for the aerobic exercise group was 112 beats per minute, compared with 75 beats per minute for those in the t'ai chi group.
The authors conclude that t'ai chi, a low-intensity physical activity, can have antihypertensive effects in sedentary older persons similar to those associated with moderate aerobic activity. Patients who practice t'ai chi need no specialized clothing or equipment, and it is accessible to those who have been sedentary and may be discouraged by the thought of aerobic exercise. Further studies are needed to determine what “dose” of activity is needed to reduce blood pressure in elderly patients who are sedentary.