WORCESTER — Jason Israel, an actuary from Syosset, N.Y., has run four full marathons and 10 half-marathons over the years.
But he had to come to Worcester this weekend to run one indoors.
That's right, indoors. Israel and 40 other runners ran a half-marathon Saturday on a makeshift 207-meter concrete track inside the DCU Center, the first race of its kind in recent memory in Massachusetts.
That's 13.1 miles. 102 laps. And more than 400 left turns.
"I thought it would be an interesting change," said Israel, 44. "I do like whimsy."
Until recently, almost all marathons were held outdoors, regardless of the weather. But a growing number of indoor events have popped up around the country in recent years — including ones in Minnesota, Wisconsin, and Ohio — to meet demand from the ever-growing number of marathoners looking for a new challenge.
The same running group that organized the Worcester event, Southern New England Athletic Association, is planning to hold a full 26.2-mile marathon (as well as another half marathon and shorter races) inside a Hartford convention center next month to form the "Arena Attack Indoor Race Series."
"It's so unique," said Ryan Lamppa, a researcher with Running USA, a nonprofit group that tracks the industry. "You are probably looking at only 300 to 500 people that compete in an indoor marathon a year, compared to a half a million plus who finish a marathon."
It also makes it easier for organizers to hold a marathon in New England and other northern regions during the harsh winter months.
"There could be a blizzard outside and we'd be fine," said Scott Sutter, the race director for the Worcester event.
Deb Bryan, 51, of Warwick, R.I., said she was already signed up for a half-marathon in Florida in February. But she entered the Worcester and Hartford indoor events to maintain her running shape at a time when other races in New England are hard to find. "This is practice," she said.
Runners also didn't have to worry about wind, rain, or snow: The temperature in the convention center was around 50 degrees — perfect for running. And the route had no hills. "It was nice and flat," said Kevin Monteiro, 24, of Peabody, who finished with his personal best time of 1 hour, 28 minutes. "It's obviously much easier" than a traditional race.
Kerri Haskins, 42, of Danville, N.H., who has run marathons in all 50 states, said this was the second time she had run an indoor half-marathon. She said one benefit of the course is that the slower runners are never far from the faster racers. "You never feel like you're in last place," she said.
Race organizers also bragged that bathrooms, the water stop, and first aid were never more than a lap away. And spectators could watch friends and relatives pass by almost every minute.
Some acted as personal support squads. Ruth Frechette, 45, from Worcester stood along the course, cheering on her boyfriend and clutching a strawberry-banana energy gel to hand off to him as he ran by.
"We see them every single turn," Frechette said.
But there are disadvantages — such as lack of scenery. Many marathons are famous for runs along the ocean, through parks and other sites, but runners at the Worcester convention center passed the same green and white walls again and again. Instead of mile markers, a digital screen flashed their names and laps as they ran over a timing mat nearby.
Organizers tried to liven up the event by hiring a disc jockey to continually pump high-energy songs, like the Dropkick Murphys' "I'm Shipping Up To Boston," through the convention center.
And to help defray the cost, they rented out space inside the track to a company holding a competition for CrossFit exercise enthusiasts, so there was a constant whir of motion inside the course — as well as along the perimeter.
Because the track was narrow, race organizers also strictly limited the number of runners that could race at the same time — splitting the field into two half-marathons. (Monteiro won the first race, while Hiroshi Oda of Cambridge won the second with an even faster time of 1 hour and 23 minutes.) They also held shorter races, including a 5K and a 10K, over the course of the day.
But it was the half-marathon that stood out because it involved so many laps and so many turns. (Some other indoor races even reverse directions every half hour or hour to help runners avoid injuries by making so many turns in the same direction.)
Bill Adamson, a police officer from Ayer who signed up for the Worcester half-marathon after getting shut out of a more traditional race, said his fellow runners, the music and the spectators helped ward off boredom. "There is so much going on," he said.
But Adamson, who has run eight full marathons, said he could never imagine running the full marathon distance on the indoor track. "No way. Absolutely not," said Adamson, 33. "Two hundred laps? I think I would lose it."
Todd Wallack can be reached at email@example.com. Follow him on Twitter @twallack.