With record low temperatures sweeping the nation, Chicagoans prepare for business as usual. Millions of residents will bundle up with scarves, hats and mittens ready to face the arctic temperatures on their daily commute.

Although those from warmer climates may think Chicagoans are crazy for braving the cold, there is another group that baffles even some of the most hardened winter veterans — Chicago runners.

Each morning, thousands of Chicago runners pound the pavement, despite temperatures that have already claimed the lives of at least three Cook County residents this winter. Some wear expensive spandex, while others run in full winter jackets. Bearded runners become adorned with icicles making them look like human Popsicles.

What is it that drives these perfectly sane individuals to swaddle themselves in spandex and warming layers in order to keep running through the harshest elements?

To a non-runner, it can seem perplexing. Watching a runner zip by with frozen snot and chapped cheeks, radiating steam, looks awful. While most would assume that these runners are dedicated but miserable, the overwhelming majority of winter runners couldn’t imagine running indoors.

Filip Latocha is the vice president of the DePaul Run Club. His organization hasn’t stopped meeting for outdoor runs, despite the frosty temperatures.

Latocha says his club does not shy away from either cold temperatures or the snow. “Sometimes we will even wear goggles,” he laughs when saying this, perhaps knowing how crazy he must seem to a non-runner.

The one thing that will keep the DePaul Run Club indoors is freezing rain, and with good reason. Moisture is a real danger in sub-freezing temperatures, and runners can become extremely susceptible to frostbite or hypothermia.

Over the past week temperatures in Chicago have dipped as low as 9 degrees below zero. The highest they have risen is a frigid 18. According to the National Weather Service, frostbite can occur within minutes if the skin is exposed to temperatures below 15 degrees. It is important for runners to know how to dress if they want to be successful running outside all year long.

Lyndsey Baum is a product manager at Fleet Feet Sports, one of Chicago’s premier retail and training companies for runners, with several locations throughout the city. Baum has a few tips for runners to be successful in winter conditions.

“You need to dress in layers, but you also need to determine what works best for you,” Baum said. “I may sometimes just need spandex, while my husband will be in a full winter coat and balaclava.”

The key she stresses, is layers.

“If you have proper layers, and understand your body it makes things easier.” Baum recommends a product called Nuun Energy Tablets. She says that adding them to warm water can be a great way to warm up before or after a particularly cold run. When asked why she continues to run outside, Baum says, “it can be very meditative outside in the winter, since there are hardly any runners out.  Being cooped up inside is not very fun.”

Being outside is the major selling point for Ryan Caturan when recruiting new runners in the winter. Caturan is a coach at Chicago Endurance Sports and helps run a program called Winter Warriors. Throughout multiple locations, hundreds of runners continue training for races during what Caturan considers to be the off-season.

“The reason we run outside is because the treadmill sucks, and you can quote me on that,” he says jokingly. “When you do winter running and don’t allow the elements to keep you inside, it shortens that winter up.”

When asked if there is a threshold for runners being able to run outdoors, Caturan says that “there is no limit for an individual runner.” For safety and liability reasons, his group does have a threshold for when they will cancel an outdoor run. Caturan says that negative temperatures, or a real feel of 20 degrees below zero is the limit for the Winter Warriors.

But just how cold is too cold? Most experts say that as long as the temperature is above 20 degrees below zero, exercise is still safe providing an individual is properly dressed. The biggest danger is exposed skin and moisture.

Runners should favor fabrics that wick sweat away from the body, like spandex or Merino wool. Cotton is not ideal, as it becomes damp and clings to the body. It is especially important to remember to bring some type of payment in case a runner becomes stranded far from home. Things like dehydration, or a fall on the ice may make it difficult for a Chicago runner to make it home in freezing conditions.

When asked if they have a policy for injured or stranded runners in the cold, a representative from the Chicago Transit Authority unsurprisingly said that “there are no free rides on the CTA.” If a runner becomes stranded in sub-zero temperature and is too exhausted to continue, they better make sure they have some means to pay for transportation home.

No matter the conditions, Chicago runners don’t care. They will continue to run through the elements in order to satisfy an addiction that even they can’t quite explain.