Rheinhardt Harrison, 10, right, with his family, from left, sister Ella Harrison and his parents Dennis Harrison and Heidi Johannesen after the Alexandria’s Running Festival half marathon Sunday May 25, 2014. (Philip Bowie/Family Photo)

Rheinhardt Harrison is such a typical hyperactive 10-year-old suburban boy — loves basketball and Xbox, grossed out by onions and girls — that it’s easy to overlook that he is one of the fastest 10-year-old distance runners in the world. Ever.

It’s no guarantee of fame and fortune when the 2028 Olympics roll around. But last month in the District, the Falls Church resident set the world record for the 10-mile run for 10-year-olds (yes, they keep records for every age). Then on Sunday, at the Alexandria Running Festival, he set what’s believed to be a world record for that age in the half­-marathon by a full two minutes, running a steady pace of 7:15 per mile to finish in 1:35:02.

That was the first time he had ever run either distance.

And when he was done with the 13.1-mile course along Eisenhower Avenue, he went on the moon bounce with his friends near the finish line.

“It was fun and hard at the same time,” Rheinhardt said of his first half-marathon. “At mile 10, I had a shoulder cramp. My dad had to massage it.” When it was over, he added, “I was tired. But it was fun after,” partly because of the moon bounce and the free massage table.

Rheinhardt Harrison, 10, running in the Alexandria’s Running Festival half marathon Sunday May 25, 2014. He broke the world record for 10 year-olds in the half marathon by more than two minutes. (Philip Bowie/Family Photo)

Child phenoms often inspire debates about how far they should be pushed, whether in gymnastics, tennis or other sports. In Rheinhardt’s case, it’s a family conversation. Rheinhardt’s parents, Heidi Johannesen and Dennis Harrison, are deeply aware of the need to provide a balance between sports and just plain kids’ stuff. Both ran track in high school and closely monitor his running and his health. Harrison has taken training and received certification from the USA Track and Field organization and helps coach the Fairfax Police Youth Club team.

“You really have to be careful with kids at all ages,” said Harrison, a vice president for the National Association of Home Builders who ran a 4:16 mile back in his high school days. “They’re going through growth spurts.”

He also said a child’s “running age,” or number of years running, is often more important than their full age, and Rheinhardt’s seven years of experience convinced his father he was able to take on 10 miles or more.

A typical week for Rheinhardt involves track practice on two afternoons (“we get lollipops after practice,” he noted happily) and a meet on the weekend. He also has basketball practice or a game each week and some Minecraft, Xbox or general running around with friends like 10-year-old Marshall Bowie. “He wants to win at everything,” said Marshall, a fellow FPYC runner. Is that annoying? “Sometimes,” Marshall said.

But it’s not always fun and games. Whether running against other boys or in road races with adults, the moments before each race make Rheinhardt extremely nervous. “He’s twirling his hair and biting his nails to the bone,” Johannesen said. “You didn’t have to share that story, Mom,” Rheinhardt interjected.

“But once he takes off,” Johannesen said, “he’s in his zone. Running has been good for him. It’s not just a physical thing — it’s providing a sense of self, and it’s growing every day.”

Rheinhardt’s 10-mile record has been certified by the Association of Road Racing Statisticians, which keeps databases of records at distances from 3,000 meters to the marathon. His half-marathon time is awaiting certification.

As an 8-year-old, Rheinhardt, a fourth-grader at Thomas Jefferson Elementary School, set meet records while winning two national championships in the 2K (1.2 miles) cross-country championships. Before that, he won two national titles on the track in the 800 meters and another in the 1,500 meters. In 2013, he moved up to the 9-10 age group and didn’t quite dominate as a 9-year-old. But in February, he turned 10, and it was time for bigger things.

“My dad promised I could run it when I was 10,” Rheinhardt said of the Cherry Blossom 10-Mile Run. “I really wanted to do it. It sounded fun.”

Though his first 10-mile run was planned as a training outing, when he broke the world record, he decided to try for another one in the half-marathon. But really, cross-country is the best to Rheinhardt.

“In cross-country, you’re running over streams and up hills,” Rheinhardt said the other night while munching on boneless chicken wings, broccoli and salad (but NOT onions). “With track, you’re just running around a circle, over and over and over,” he said, emphasizing the monotony with a slouch of mortal boredom.

And a half-marathon through the streets? “Not bad. There’s lots of stuff to look at. I saw this water park there [Cameron Run]. I really want to go.”

Rheinhardt’s running career began when he was 3, he said. “I think I ran a 2K, and I ran past the finish line, and I didn’t want to stop. At least that’s what my dad tells me.”

His father limits his distance running to about 10 to 15 miles per week, and he did not run at all in the week before the 10-mile or half-marathon races.

Rheinhardt’s adult competition is noticing him, too. When his mother happened to meet a fellow runner recently and Rheinhardt’s name came up, the man said: “You’re Rheinhardt’s mom? He’s the one at the 5K races we’re trying to beat,” Johannesen recalled. Harrison said runners at the starting line’s front group, where race organizers often try to put the elite competitors, now make room for Rheinhardt.

To get a sense of how fast this 10-year-old is, his personal best in the mile is 5:44 and his best time in a 5K is 19:01. Many adults would love to run times like that.

Marc Davis, a former Olympic steeplechase runner and holder of the American 5,000-meter road race record from 1996 until last month, has known Rheinhardt and his family for several years. “He’s a very relaxed kid,” Davis said. “His parents are doing it right and allowing him to be in the sport the way he wants to do it. To see him run the shorter distances is one thing, but to run the longer distances and be equally successful is pretty impressive.”

Next up is the “boring track” season and a goal of national titles in the 800- and 1,500-meter runs. Beyond that, he would like to attend the University of Oregon, cradle of great distance runners, including his favorite, former star Steve Prefontaine. Then the Olympics, and after sports?

“I’d like to be a dancer,” he announced, stepping into an Irish jig along with his 8-year-old sister, Ella. “Or work in a running store, or be a running coach.”

On Tuesday, two days after running his record half-marathon, his father held him out of track practice. “Rest is just as important as pushing it,” Harrison said. But after talking about his running was over, Rheinhardt turned to his father and said, “Can I run, Dad?”