By Jeremy Ross

CHICAGO (CBS) — Street closures are set up for runners from across the globe who tend to stay in the hotels along Michigan Avenue in preparation for the 2019 Chicago Marathon.

Some are nervous — others excited — most noting the weather is on their side this year.

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More than 40,000 runners will pound the pavement across Chicago’s neighborhoods Sunday morning in an effort to complete the 26.2 mile race, which some have trained months for and others have set out to accomplish as a life milestone.

The course running along the lake shore and nearby communities means some streets have been blocked off and traffic detours are in place.

Most elite runners will finish in about two hours. Others will take four or five hours to complete the marathon’s grueling length.

But most believe the elements will be on their side in Sunday’s race, as cooler temperatures than in years past settle in.

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A study in Runner’s World showed when researchers analyzed the finishing times of 1.8 million marathoners over a 10-year period, they found that a race-day temperature of 43 degrees produced the quickest times overall.

Other studies, however, suggest colder conditions only have a minimal impact on times — on average cutting mere seconds off finish times.

But many consider any edge a bonus when running for hours.

“I ran this morning in shorts and a long sleeve shirt and it was perfect,” runner Sarah Martin said. “I run much faster in the cold.”

Another competitor said the weather was the “most perfect weather we could ask for.”

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“I ran it back in 2010 and it was very hot, so I’m excited to run it when it’s gonna be cool,” Sarah Jackson said. “Just the wind, if that could cut down, that would be amazing.”