Cardiovascular disease (CVD) is the leading cause of death worldwide. One of the most important measures for their prevention is physical activity.
In today’s world, people often have to walk, run, ride a bicycle and do other exercises in polluted air. Scientists have previously found that contamination with particles with a diameter of 2.5 to 10 micrometers (PM2.5 and PM10) is associated with an increased risk of CVD. Thus, dirty air has the potential to reduce the protection against CVD that physical activity provides. Until now, little has been known about the effects of exercise on heart and vascular health at potentially harmful levels of air pollution.
In a new study, researchers at Seoul National University analyzed data on nearly 1.5 million people between the ages of 20 and 39. The study participants lived in Korean cities. They were monitored from 2013 to 2018, during which time they underwent two medical examinations. Young people periodically filled out questionnaires in which they talked about their physical activity during the last week.
Scientists measured the physical activity that study participants underwent in metabolic equivalents (MET). 1 MET – the amount of energy that a person burns at rest is approximately 1 kilocalorie per kilogram of body weight per hour. With moderately severe physical activity, a person spends about 3-6 times more energy. The European Society of Cardiology recommends physical activity of 500-999 METs per week (15-30 minutes of moderate-intensity exercise 5 times a week).
“We found that in people aged 20-39, the risk of cardiovascular disease increased with decreased physical activity,” said Dr. Seong Rae Kim, co-author of the study.
At the same time, Kim said, physical activity of more than 1000 METs per week (which is above the usual recommendations) in polluted air (the concentration of PM2.5 particles is higher than 26.46 micrograms per cubic meter) can be dangerous to heart and vascular health. That is, in such conditions, high activity can be more harmful than physical passivity.
With lower air pollution, any activity, including intense activity, was beneficial.
“Overall, our data show that physical activity in the amounts recommended by the European Society of Cardiology is associated with a reduced risk of cardiovascular disease in young people. But when pollution levels are high, exercising more than the recommended amount can be harmful, ”summed up Sang Min Park, lead author of the study.