Ten years after its first run, the Lowell Kinetic Sculpture Race returned to Market Street in Lowell with competitors gathering at 9 a.m. and the race starting at 11:30 a.m., an organizer said. The course runs through downtown, crosses the cobblestones of Bridal Street (referred to by organizers as “Bone Shaker Alley”), loops twice around the rotary by the Tsongas Center, traverses a mud pit and proceeds about three miles to the Lowell Heritage DCR State Park Stamps Pavilion, where competitors enter the Merrimack River for about 100 yards before exiting the water and returning to a finish in town, organizers said. The event began in 2016 after Michael Roundy, a University of Massachusetts Lowell art professor, told organizers about a human-powered kinetic sculpture race he had seen in California; after a year of fundraising, the first Lowell race was held in 2016, according to the remarks. Organizers invited the public to join future runs and to learn more at Lowellkinetic.com.