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It’s a question faced by many runners: When running along a street that has no sidewalk, are you better off to go with traffic or against it?

Researchers in Finland found that people moving against traffic have, on average, a 77 percent lower risk of being struck and injured by a car. The reason is simple: You can’t react to something you can’t see.

“Running against traffic allows you to see oncoming vehicles and to react to them,” said Jean Knaack, executive director of the Road Runners Club of America. “If your back is to incoming traffic, you’re far less likely to react if a car is not giving you an adequate right of way.”

Dennis Barker, head coach at Team USA Minnesota, suggested that runners put themselves into the driver’s seat, figuratively speaking, by recalling what it was like the last time they encountered someone on foot on a two-lane road.

“As a driver, I appreciated others who walked or ran facing traffic because it helped me see them better when they adjusted their position as I approached,” Barker said. “I, in turn, adjusted my position. We both took responsibility for each other’s safety.”

Runners should practice “defensive running” in the same vein as defensive driving, he said. Defensive runners always look for oncoming distracted drivers encroaching on their space.

“Staying aware provides crucial time to avoid a distracted driver who may not be taking a straight line,” Barker said. “A runner going with traffic is not aware of what’s coming and is at the mercy of the driver.”

The U.S. Department of Transportation said that in 2015 there were nearly 3,500 fatalities and 400,000 pedestrian injuries because of distracted driving, primarily from people manipulating handheld devices. “Never assume a driver sees you,” the agency recommends.

Todd Straka, a Colorado race organizer and publisher of the Boulder Running website, suggested that runners borrow a page from bicyclists.

“Bikers often have blinking lights, even during the day. I would suggest runners wear something like that so they can be seen from afar,” he said.

Some people who run with traffic believe that if they are hit, the impact will not be as severe because they are moving in the same direction as the car. Rebecca Metzler, associate professor of physics at Colgate University who also is a runner, said that the difference isn’t significant. “Your reaction time is far more important, and that smaller force is outweighed by the ability to get out of the way in the first place,” she said.

There are two instances, however, in which experts recommend running with traffic: as you approach the crest of a steep hill, and as you round a sharp turn. In those situations, the runner and the driver may not see each other until it’s too late. The solution, experts say, is to cross the road in advance of the hill or the turn and run with traffic until it’s safe to cross back over to the other side of the road.