Lots of runners back out of races they signed up for, but Kat Clewley backed into hers.

Clewley, who lives in Burlington, Ont., ran Sunday's Road2Hope Hamilton Marathon backwards. Her official time was 4:48:42, which qualifies her to hold the first Guinness World Record for a woman accomplishing the feat, she says.

Kat Clewley waves to supporters while running backwards during the Hamilton Marathon on Sunday. (Jim Commerford/Twitter) She measured the exertion in how much she had to eat during the 42-kilometre course.

Usually during a marathon, Clewley might consume one packet of energy gel, she said.

Sunday, she had three. And an energy bar. "That's how hard I was working," she said.

And the former goalkeeper for Canada's women's soccer team at the Pan Am Games found she had to take off her long-sleeve shirt, finishing the November race in a tank top and shorts.

"I've done an Ironman, a lot of 100-mile runs, Boston Marathon, Mudderella, you name it," she said. "This was the hardest thing I've ever done."

She said she was thankful for the support of her family and colleagues and friends from the YMCA on Rymal Road in Hamilton, many of whom came out Sunday to cheer her on. Clewley is a program manager there, and she organized running training groups for Saturday's five- and 10-kilometre races, as well as Sunday's half and full marathons finishing at Confederation Park.

Clewley used the attention her goal brought to raise money for the YMCA's after-school and summer program, Beyond the Bell, as she trained for the race.

.<a href="https://twitter.com/UltraFitKat">@UltraFitKat</a> making history. Proud of you, Kat. .<a href="https://twitter.com/ymcahbb">@ymcahbb</a> .<a href="https://twitter.com/HMRoad2Hope">@HMRoad2Hope</a> <a href="https://twitter.com/hashtag/road2hope?src=hash">#road2hope</a> <a href="https://twitter.com/hashtag/HamOnt?src=hash">#HamOnt</a> <a href="https://t.co/W22ts24GWA">pic.twitter.com/W22ts24GWA</a> —@BDWebber

Retro-running

Clewley got into the sport known as "retro-running" somewhat backwards, too.

This summer she was out on a run with her dog, Vanilla. She worried Vanilla would drop yet another $10 ball along the path, so Clewley turned around to keep an eye on her companion. She ran backwards for 10 minutes, enjoyed herself and went home to Google it.

Sure enough, there's a championship in Europe every year. Clewley will travel to Germany to represent Canada next July.

The race went pretty smoothly Sunday, she said. Heavy winds complicated things, especially for her sister, who was riding a bike alongside and filming the effort.

Clewley found some relief going downhill for seven kilometres on the stretch of the Red Hill Valley Parkway that's part of the race route. When you run backwards, she explains, you spend all of your time on the balls of your feet, so when her heels were hitting the ground on the downhill stretch it was a nice change.

She did have a fall, she said. Clewley tripped over her own feet crossing a bridge over the QEW.

"There's the QEW right underneath," she said. "Of all places to fall."

In the end, she finished under five hours, which was the mark the Guinness World Records organization told her she needed to shoot to be under for the record to count, she said. The fastest man to run a marathon backwards is Xu Zhenjun, who ran in 3:43:39 in 2004 in Beijing.