New European research has found that exercise can still help reduce the risk of a heart attack even when carried out in areas with moderate to high levels of traffic pollution.
Carried out by researchers in Denmark, Germany and Spain, the new large-scale study looked at 51,868 Danish adults age 50-65 to see if exercise could still help reduce the risk of first and recurrent heart attack even when participants were exposed to air pollution, which can increase the risk of cardiovascular disease including heart attacks, asthma and chronic obstructive lung disease.
The researchers analyzed the participants' outdoor physical activity levels, including sports, cycling, walking and gardening, and their exposure to nitrogen dioxide (NO2), a pollutant generated by traffic.
Participants were also asked to self-report on other lifestyle factors as well as their physical activities.
Over the 17.7-year period, there were 2,936 first heart attacks and 324 recurrent heart attacks.
The team found that as expected, higher levels of air pollution were associated with more heart attacks, with those living in higher risk areas showing a 17 percent increased risk for first heart attack and 39 percent for recurrent heart attack, compared to participants with low residential NO2 exposure.
However, the results also suggested that regular physical activity reduced the risk of both first and recurrent heart attack, even in areas with moderate-to-high levels of traffic pollution,
More specifically, those who participated in sports had a 15 percent lower rate of initial heart attacks and those who cycled had a 9 percent lower risk, regardless of air quality, with moderate cycling for four or more hours per week also reducing the risk for recurrent heart attack by 31 percent.
There was also a 58 percent reduction when all four types of physical activity were combined, together totalling four hours per week or more, regardless of air quality.
"Currently there is little data on whether poor air quality cancels out the protective benefits of physical activity in preventing heart attacks," said Kubesch. "Our study shows that physical activity even during exposure to air pollution, in cities with levels similar to those in Copenhagen, can reduce the risk of heart attack."
"Our research supports existing evidence that even moderate levels of regular physical activity, such as active commuting, are sufficiently intense to get these health benefits."
The results can be found published online in Journal of the American Heart Association, the Open Access Journal of the American Heart Association/American Stroke Association.