Gosser was told 28 months ago by Thomas Jefferson University Hospital surgeons that he might never walk again following a slip-and-fall accident in Old City.

But tomorrow, the 5-foot-11, 179-pound Neshaminy High School science teacher and former track coach is set to be one of 1,500 triathletes competing in the Sprint Triathlon, an event in which competitors will swim 0.9 kilometers (just over half a mile) in the Schuylkill, bike 24 kilometers (just under 15 miles) in Fairmount Park and run 5 kilometers (just over three miles) along Martin Luther King Drive.

The event starts at 8 a.m. at Martin Luther King Drive and Black Road and should end at about 9 a.m. at the same site.

The rest of the participants are scheduled to compete Sunday in the Olympic Triathlon, in which they will swim 1.5 kilometers (just under one mile), bike 40 kilometers (just under 25 miles), and run 10 kilometers (just over six miles). They are professionals and will be vying for $13,500 in prize money.

That event starts at 6:55 a.m. at St. Joseph's University Boathouse on Kelly Drive and should end about 8:45 a.m at Martin Luther Drive and Black Road.

The Cancer Center at the Children's Hospital of Philadelphia will benefit from the event, which was ranked among the top five triathlons in the nation last year by Outside magazine.

This will be Gosser's first experience as a triathlete and, much like his outlook after he fractured his pelvis and a vertebra after slipping on ice and landing on his buttocks on Feb. 25, 2007, his outlook is cautiously optimistic.

"My goal is to finish my first [triathlon]," said Gosser, who was a sprinter and pole vaulter on the Father Judge High School varsity track and field team in 1997. "To say I did it. . . . This is a way to thank my surgeons. They got me here."

Gosser remembers when those surgeons were not optimistic about his walking again when they inserted five screws and two rods to hold the vertebra in place and five screws and two rods into his pelvis during his three-week hospital stay.

But 12 weeks later, Gosser was able to walk freely.

Physical therapy followed, and again he amazed the medical professionals by swimming instead of walking in a pool and jogging instead of walking on a treadmill.

On March 13, 2008, at Gosser's request, doctors removed the screws and rods. A few weeks later, he was running a mile a day as he did before the accident.

"It was a goal to be able to get back all of my physical strength and prove that I am fine," Gosser said.

Tomorrow, he gets his chance.