Some of the runners who competed in a race in Cape Cod, Massachusetts, this weekend weren't even there.
Physically, that is.
At the New Balance Falmouth Road Race, runners were allowed to compete simply by downloading an app on their tablet and hopping on a treadmill.
The app, created by Outside Interactive, used video footage to take virtual runners on the actual course from Sunday's race. The goal was to draw runners who couldn't attend in the flesh; for Falmouth, that included 3,000 runners who were turned away this year because of signup limits, along with others who weren't able to travel to Cape Cod.
"This gives them an opportunity to sign-up like they would the normal live race but at a reduced fee and they would then receive an email that would contain the virtual runner app for IPad for Android, the course video, an activation code, a downloadable bib, which they can actually use," Gary McNamee, president and founder of Outside Interactive, told Mashable.
Eighty-three virtual participants have reported their results so far, McNamee said.
Dave McGillivray FRolling down after completing the Virtual Falmouth road race using outsideinteractive.com #runnerspace A photo posted by @thefroller on Aug 16, 2015 at 4:01am PDT
Although the physical race happened on Sunday, participants can enter results through Monday, as some didn't have immediate access to a treadmill but still wanted to participate. Others who don't have a treadmill or tablet were able to run outside and submit their results manually.
It cost $40 to participate virtually, compared with $65 to run in the outdoor race. Virtual registrants received an official finisher's mug and a race keychain; their times will be posted online, but kept in a separate category from the outdoor race.
The price seemed fair to Jennifer Walker, who plans to race from a treadmill at her gym in Baltimore.
A former Boston resident, Walker has always wanted to run Falmouth. But with two young children and a husband who's a physician, she said, traveling can be a challenge.
"This is so easy for me. All I have to do is pretty much do what I normally do -- go run on the treadmill," Walker said.
After working with Falmouth, McNamee said the company decided to cap virtual participants at 100. "Some folks were confused about the live versus virtual race and what they were signing up for, so we decided to make it a pilot so we could learn from it with a containable number," he said. "Being the first race and first year, we don't know what we don't know."
Although the company debuted this technology at the race on Sunday, Outside Interactive has filmed 10 more races that could be developed into virtual versions, McNamee said.
While the technology for virtual racing is relatively new, the idea isn't.
For years, members of the military in far-flung locales have organized their own races to coincide with major events, such as the Chicago Marathon. In 2007, American astronaut Sunita Williams ran 26.2 miles on a space station's treadmill during the Boston Marathon.
The technology from Outside Interactive borrows from that concept but tries to create an authentic simulation of the actual course.
When the video approaches a hill, for example, it prompts runners to increase the elevation on their treadmill. If runners want to pick up the pace, they increase the treadmill speed and then adjust a pace setting on the video, which can speed up or slow down.
"There's so many runners that just do it for the experience and the course and having the virtual run you get that feel of being on the course and you get to experience it still in some way," McNamee told Mashable.
As close as virtual running gets to the real thing, though, race directors predict it will always fall short.
"Truth be told, I don't think you can compare the two," said Dave McGillivray, director of the race, who is also director of the Boston Marathon. "It'll never replace obviously the experience of running the race in person. Nothing will ever replace that. But it's an alternative to that."