Leaders in the Chicago Marathon, courtesy viewer Michael V. Paskvan. (Michael V. Paskvan)
Courtesy Eli's Cheesecake on Twitter. (@ElisCheesecake on Twitter)
Courtesy viewer Patty Bruno on Twitter (@brunopatty on Twitter)
Viewer David Kahn took this photo before the marathon in the South Loop. (@DavidKahn1009 on Twitter)
(ABC7's Ben Bradley)
CHICAGO (WLS) -- Running 26.2 miles is an epic test of endurance for most people, but 45,000 hardy souls are up for the challenge in the 37th annual Chicago Marathon.