Older adults who don’t do much exercise, and whose blood pressure is getting to the point where they may need treatment, should perhaps consider swimming as a way to help bring it back down, at least that is what a small US study of sedentary over-50-year-olds might suggest. The study was published early online in The American Journal of Cardiology earlier this month.

Swimming is an ideal form of exercise for older, sedentary people because it puts little weight-bearing stress on the body and is not likely to lead to overheating. However, despite this, we know little about the effect this form of exercise has on the arteries and blood pressure, write the authors, from the University of Texas (UT) at Austin.

They found that 12 weeks of swimming significantly lowered blood pressure and improved the function of arteries in a group of sedentary, unmedicated over-50s whose blood pressure was on the verge of “unhealthy” (prehypertension) or in stage 1 of hypertension.

For their study, Dr Nantinee Nualnim, of UT’s Cardiovascular Aging Research Laboratory, and colleagues, recruited 43 sedentary people aged over 50 (average age of 60) who also had prehypertension or stage 1 hypertension but were not on any medication.

They randomly assigned them either to do 12 weeks of swimming or 12 weeks of gentle relaxation exercises (the controls).

The researchers also took a number of measurements before, during, and at then end the 12 weeks, including measures of height, body weight, body fat, blood pressure, vascular function, blood glucose and cholesterol.

Before the 12 weeks, there were no significant differences between the swimmers and the controls.

Body mass, body fat (adiposity) and blood levels of glucose and cholesterol did not change in either group throughout the 12 weeks.

However, they found that blood pressure (casual systolic) fell from 131 to 122 mm Hg in the swimming group (note that 120 is the “ideal” for a healthy heart, as in 120/80).

There were also significant changes to vascular function, such as the “stiffness” of arteries, in the swimming group. The authors note:

“Swimming exercise produced a 21% increase in carotid artery compliance (p