On a recent Sunday morning, Kate Silvester ran a 5K. She didn’t have to worry about where to park to get to the starting line in time: She just headed out to a biking and running path behind her house and onto a back road.

Her race was a virtual 5K associated with the NYC Half, which was run in New York the same day.

Virtual challenges and runs are part of a growing trend in recreational running: doing a race whenever you can, wherever you can, and still feeling as if you’re part of the crowd, even if you’re running alone.

Bob Bickel, founder of the race registration platform Run Sign Up, said the organization saw virtual races pop up “in earnest” about five years ago. One of the first popular virtual runs, he said, was that of Jeff Galloway, a running coach who trains runners using a run-walk-run method. In 2018, 1,050 people finished Mr. Galloway’s virtual events, which included a 5K and half marathon.

“People are used to running with their apps, and I think more and more people are comfortable with connecting virtually,” Mr. Bickel said, “whether it’s on Facebook or Instagram or Snapchat, people can actually have friendships even though they don’t see each other.”