Washington: Physical activity during work and leisure time significantly lowers the risk of heart attacks, while ownership of a car and television is linked to an increased risk, particularly in low and middle-income countries, a worldwide study has shown.
The findings come from the INTERHEART study, a case-control study of over 29,000 people from 262 centres in 52 countries in Asia, Europe, the Middle East, Africa, Australia, North and South America.
Claes Held, the first author of the study, who is an associate professor at Uppsala Clinical Research Center and the Department of Cardiology, at Uppsala University Hospital, Sweden, and his colleagues from Canada and the USA, compared the work and leisure exercise habits of 10,043 people who had suffered their first heart attack with 14,217 healthy people.
They asked the participants whether their work was mainly sedentary, or predominantly walking at one level, or mainly walking including walking uphill or lifting heavy objects, or heavy physical labour.
For physical activity during their leisure time, participants could select from four possible responses: mainly sedentary (sitting activities, like sitting reading, watching TV), mild exercise (minimal effort activities, like yoga, fishing, easy walking), moderate exercise (moderate effort, like walking, cycling or light gardening at least four hours a week), and strenuous exercise (when the heart beats rapidly, like running, football or vigorous swimming).
They also asked about the ownership of goods such as a car, motorcycle, radio/stereo, TV, computer, land and livestock.
After adjusting for various confounding factors such as age, sex, country, income, smoking, alcohol, education, health, diet etc, they found that people whose work involved either light or moderate physical activity had a fifth or a tenth lower risk of having a heart attack when compared to people whose occupation was mainly sedentary.
However, heavy physical labour did not reduce the risk at all. During leisure time, the risk of a heart attack was lower for any level of exercise when compared with being mainly sedentary, reducing by 13 percent for mild activity and 24 percent for moderate or strenuous activity.
People who owned both a car and a TV, both indicators of a sedentary lifestyle, had a 27 percent increased risk of a heart attack, compared to those who owned neither a car nor a TV.
A greater proportion of people in low-income countries had sedentary jobs and undertook less physical activity in their leisure time, than in middle- and high-income countries.
“These differences in physical activity were most pronounced regarding leisure-time activity,” the authors of the study said.
“This may partly be explained by differences in education and other socio-economic factors. In addition, this may also reflect differences in culture and in climate. The likelihood of a subject performing leisure-time PA in tropical or hot climate zones is lesser than in more temperate areas of the world,” they said.
The authors concluded that daily moderate physical exercise should be encouraged in everyone to prevent heart disease.
“The data have some real-life implications. One suggestion may be for the lower income countries to be more involved in promoting physical activity as their societies starts to use more labour-saving devices, so as to counter-act the inactivity that this can lead to; however, it also important to promote physical activity in all parts of the world,” Held said.
The study has been recently published online in the European Heart Journal.