Study in polluted Taiwan shows regular exercise still prevents high blood pressure

People who regularly exercise are at a lower risk of high blood pressure, even if they live in highly polluted areas, found a new research, since the risk-benefit relationship between air pollution and physical activity is a major concern as more than 91% of people worldwide live in areas where air quality fails to meet World Health Organization (WHO) guidelines.

The paper published in the American Heart Association’s flagship journal Circulation, is based on a study of more than 140,000 adults without high blood pressure in Taiwan, who are followed for five years. Researchers classified the weekly physical activity levels of each adult as inactive, moderately active or highly active.

Researchers also classified level of exposure to fine particulate matter (PM2.5) as low, moderate and high. PM2.5 is the most commonly used indicator of air pollution. High blood pressure was defined as 140/90 mm Hg, though the American Heart Association 2017 Guideline defines high blood pressure as 130/80 mm Hg.

Exercise helps despite high pollution 

Study author Xiang Qian Lao, an associate professor at the Jockey Club School of Public Health and Primary Care at The Chinese University of Hong Kong in Shatin, said: “While we found that high physical activity combined with lower air pollution exposure was linked to lower risk of high blood pressure, physical activity continued to have a protective effect even when people were exposed to high pollution levels. The message is that physical activity, even in polluted air, is an important high blood pressure prevention strategy.”

Highlights of the study show that people who are highly active and exposed to low levels of pollution had a lower risk of developing high blood pressure, whereas those who were inactive and exposed to highly polluted air had a higher high blood pressure risk.

High risk levels

Each increase in PM2.5 level was associated with a 38% increase in risk of incident hypertension, whereas each increase in physical activity level lead to a 6% lower risk of hypertension, suggesting that reducing air pollution is more effective in preventing high BP.

Regardless of pollution level, people who exercised moderately had a 4% lower risk of high blood pressure than those who didn’t exercise. People who exercised at a high level had a 13% lower risk of high blood pressure than those who don’t.

The findings of this study are limited to air pollution because it only included people living in Taiwan, where ambient air was moderately polluted (the annual PM2.5 concentration was 2.6 times of the limit recommended by the World Health Organization).