He ran his first race when he was a preschooler. Now the first-grader is a regular on the weekend road-race circuit in the Washington, D.C., suburbs, crossing the finish line alongside adults five times his age. He's active in youth track and cross-country events, too.
"He's looked up to in school. He's known as 'the runner.' Kids in fifth grade want to race him," says his dad, fellow runner Dennis Harrison.
Rheinhardt is among an increasing number of children pounding the pavement for fun.
"Kids' runs are taking off," says Bart Yasso, a writer and running expert at Runner's World magazine, who attends races almost every weekend.
Yasso says that in recent years many race organizers have added 1-mile "fun runs" to their agendas in an effort to accommodate adult runners who drag their little ones along to events. More proof of the trend: Until recently, the youngest award category at many races was "18 and under," but now you see that group broken down further by age, says Kathy Dalby, event director for Pacers Running Stores in the D.C. area.
The Marine Corps Marathon 1-mile fun run, which took place a week ago in Washington, drew 3,000 children this year, many of whom are the kids of marathoners, says Tami Faram, public relations coordinator for the event.
"We've grown from a little over 670 our first year 11 years ago," says Faram, who holds the fun run in the Pentagon's parking lot the day before the marathon. "When they crossed that finish, they got a medal put around their neck by a U.S. Marine."
And while medals, T-shirts and goody bags are a big draw from a child's perspective, organizers say the rewards run deeper.
"Running is the vehicle of showing them they can achieve," Yasso says.
Some organizations have other goals as well.
"Our mission is to educate and prepare girls for a lifetime of self-respect and healthy living. So while running is part of the program, it's just a piece of it," says Elizabeth Kunz, president of Girls on the Run International, a non-profit that provides schools and communities with the blueprints for a 12-week program that culminates in a 5K race.
The group, founded in 1996 in Charlotte with 13 girls, now boasts more than 70,000 participants ages 8 to 12 from 3,700 locations. Training is combined with talks on self-esteem and social challenges such as bullying and gossip.
"It's very inclusive," says Dalby, who helps coordinate three big D.C.-area Girls on the Run events, too, all coming up this month and next. "Girls can walk or run depending on their fitness level. We just want them to go out there and have at it."
Best part about a kids' runs? Standing at the finish line.
"Running is just so natural for a kid - 99 percent of them finish with a smile on their face," Yasso says. "Put that same camera on an adult race, and they look like they're going to die."
(Copyright © 2010 USA TODAY)