Air Quality, Not Just Fitness Level, Impacts Marathoners' Finish Times

THURSDAY, Dec. 26, 2024 (HealthDay News) -- Runners put a lot of thought into how much they must eat and drink to endure a 26.2-mile marathon, properly fueling their bodies to sustain a record-setting pace.

But the quality of the air they huff and puff during endurance events could also play a key role in their performance, a new study says.

Higher levels of air pollution are associated with slower average marathon finish times, according to findings published recently in the journal Sports Medicine.

“Runners at that level are thinking about their gear, their nutrition, their training, the course, even the weather,” lead researcher Elvira Fleury, a doctoral student at Harvard University, said in a news release. “Our results show that those interested in optimizing athletic performance should consider the effect of air pollution, as well.”

Runners’ average finish times on a marathon steadily decreased for every increase in particle pollution of one microgram per cubic meter of air, results show.

Men finished 32 seconds slower on average for every increased unit of air pollution, and women finished 25 seconds slower, researchers found.

These effects also appeared to be more pronounced in faster-than-average runners, researchers said.

“This means that air pollution can be a health risk not just for those who are elderly or susceptible — it can negatively affect even the most healthy and well-trained among us,” senior researcher Joseph Braun, a professor of epidemiology at Brown University, said in a news release from the college.

For the study, researchers analyzed data from U.S. public marathons conducted between 2003 and 2019, involving more than 1.5 million male runners and more than 1 million female runners.

The research team compared the runners’ finishing times with air quality data captured on event days, including the amount of particle pollution in the air along different points of the marathon route.

“This really sophisticated spatial-temporal model of particulate matter allowed us to plot pollution at every mile of every course,” Fleury said. “Without a model like this, it wouldn't have been possible to look at so many different marathons in different states across different years.”

Researchers specifically looked at levels of fine particle pollution, which are airborne particles smaller than the width of a human hair or grain of fine beach sand, according to the Environmental Protection Agency.

These airborne particles are typically generated by fossil fuels burned by cars and power plants, although in recent years, wildfires have contributed to such pollution.

Previous studies have shown that particle air pollution is associated with overall risk of death, as well as risk of heart disease, breathing problems and lung cancer, researchers said.

Air pollution could be harming marathon runners’ performance by causing increases in blood pressure, constricted blood vessels, impaired lung function, and perhaps even short-term changes in brain function, researchers speculated.

“People who can complete a marathon are generally quite healthy, and we can assume they have honed their cardiorespiratory fitness,” Braun said.

“This study revealed a negative impact from air pollution, even at levels below current health-based standards, on these very healthy people,” Braun continued.

These findings support efforts to reduce pollution emissions by shifting motor vehicles and power plants away from fossil fuels, researchers concluded.

More information

The Environmental Protection Agency has more on particle pollution.

SOURCE: Sports Medicine, journal study, Dec. 18; Brown University, news release, Dec. 18, 2024