Weekend Reads | What's the Best Exercise to Lower Your Blood Pressure?

by Kevin Schofield

The conventional wisdom is that exercise will help lower your blood pressure, and for years doctors have recommended aerobic exercise, such as walking, running, and cycling, as the most effective form of exercise for that purpose. But since that became the prevailing view, many new kinds of physical training have been developed. That leads to an important question: Is aerobic exercise still the best kind of exercise for lowering blood pressure? A group of researchers in the U.K. set out to answer that question, and their report is exactly the kind of research we hope doctors perform before they hand out advice.

The researchers approached the problem as a "meta-review": Rather than do new research on their own, they sought to collect and analyze the huge body of existing research, published over many years, on the cardiovascular effects of various forms of exercise. They found 270 studies, which involved over 15,000 test subjects.

Analyzing a large body of work like that isn't easy, because the studies often aren't "apples to apples" comparisons; many variables need to be controlled for, including the demographics of the test subjects and the level to which they suffer from hypertension (high blood pressure). They also needed to review each study for signs of potential bias, something that is far too common in consumer-related health fields where new health products and services are constantly being introduced with great fanfare.

They grouped various exercise regimens into one of five categories:

• Aerobic exercise training (AET), such as running, cycling, and walking.
• High-intensity interval training (HIIT), described as "short bouts of high-intensity exercise separated by short periods of recovery at lower intensity."
• Dynamic resistance training (RT): exercising the full range of muscles under tension or resistance.
• Isometric exercise training (IET): contracting muscles without any movement in the surrounding joints, such as "wall squats" or leg extensions.
• Combined training (CT) that brings together more than one of these categories into a training program.

When the smoke cleared after running the numbers, they found a few surprising things. First and foremost, aerobic exercise was not the most effective at lowering blood pressure; instead, isometric exercise won out. Apparently we should all be doing a lot more wall squats, too: of the various forms of isometric exercise, that one came out on top with the greatest reduction in blood pressure.

Perhaps even more surprising, the researchers discovered that while those participating in aerobic exercise still saw some reduction to their blood pressure, doing so less frequently led to greater reductions, i.e., running three times a week was better than running six times a week. But they also found that not all aerobic exercise had the same effect: In particular, walking had a much smaller impact than cycling or running. This suggested to the researchers that the intensity level of exercise is an important factor in how much it reduces blood pressure.

Overall, the benefit of exercise on blood pressure depended heavily on what your blood pressure was to begin with: Those with higher levels of hypertension saw the greatest benefit from exercise.

The researchers note that the 270 studies varied widely in their design and thus, not surprisingly, in their results as well, making it more difficult to have a high level of confidence in the statistical value of this kind of meta-analysis where a number of studies are rolled up together. They also found a fair number of papers with apparent bias that they needed to reject, as well as other concerning factors, such as variability in how well study participants complied with the training regimen. Nevertheless, the results they found suggest that health care professionals should probably revise the guidance they give us on exercising to improve our blood pressure, given that the conventional wisdom apparently isn't as wise as we thought.

It's time to do some wall squats! Who's with me?

Exercise training and resting blood pressure: a large-scale pairwise and network meta-analysis of randomised controlled trials

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