By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

A program of regular exercise is often advocated for people with hypertension, on the grounds that it may lower the blood pressure, help to promote weight loss, and improve the blood lipids (particularly the HDL cholesterol). Studies investigating its effects on blood pressure have used walking, running, or bicycling, but hitherto not swimming as the type of exercise.

A study conducted at the University of Tennessee investigated the effects of swimming in 18 people with mild hypertension. Twelve were put in the swimming training group, and the other six served as controls, who did not start any exercise program. The training consisted of swimming for 45 minutes on three days a week for 10 weeks, at a target heart rate of 60% of the maximum. The average distance swum during each session increased from 880 meters at the start of training to 1590 meters at the end.

The resting blood pressure decreased in 11 of the 12 subjects who completed the training program, the average decrease being 7mm Hg in systolic and 3 mm Hg in diastolic pressure. No changes occurred in the control group. Heart rate decreased by six beats a minute. Many of the subjects were somewhat overweight, but no changes in weight occurred during the study.

Doctor's comments

This is the first study to document the effects of swimming on blood pressure, despite the fact that this form of exercise is often recommended for the treatment of hypertension. It is of interest that the effects on blood pressure could not be attributed to weight loss or any change in diet. One of the advantages of swimming is that it can be recommended for people who are overweight or have arthritis, both of which may limit their ability to do other forms of exercise.

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