Stair-climbers ascend steps of Willis Tower for 15th annual 'Skyrise Chicago'

CHICAGO (WLS) -- Hundreds of people raced to the sky for a good cause Sunday morning inside Chicago's tallest building.

More than 1,700 climbers ascended the steps to the 103rd floor of the Willis Tower for the world's largest indoor stair climb.

"I just love this race and I do it every year," climber David Hanley said.

The climb is part of this year's Skyrise Chicago event. Back for its 15th year, the event benefits the Shirley Ryan Ability Lab, which helps people rehabilitate from serious injuries.

"Every year it gets bigger and better," Shirley Ryan Ability Lab COO Laura Ferrio said. "You can feel the energy up here."

Veteran stair climber, 66-year-old Karen Geninatti, made it to the top in just 21 minutes.

"When I climb the stairs, I think about the people who cannot climb and how fortunate I am to be able to do this," Geninatti said.

The Willis Tower, one of the tallest buildings in the world, has 110 floors.

"It was really challenging," first time climber Brian Baker said. "It was steeper than I thought."

Current and former ability lab patients and their supporters attended the event to cheer on the climbers taking on the 2,109 stairs to the tower's Skydeck on the 103rd floor.

Chicago Police Department Sgt. Mike Dineen climbed the stairs for his 15th time.

"It's gotten bigger every year, which is really nice," Dineen said. "There's just more and more people."

Dineen suffered a brain injury a few years ago and was treated at the Shirley Ryan Ability Lab. He said he participates in the annual event to thank them for the care they gave him.

"They're the best... they taught me to walk and talk again," Dineen said.

The event is expected to raise over $1 million.

"It makes me feel good being around all these people and its makes my body feel good," climber Steven Curry said.

Organizers say everyone who climbs also does it for their own reasons.

"Here you can see what you just physically accomplished as well as feel good about what you just did," SkyDeck Chicago general manager Randy Stancik said.