The world—running and not—had its eyes on the Flying Pig Marathon this past May after a 6-year-old boy completed the race with his family in 8 hours and 35 minutes.

It wasn’t the finish itself that caused an outcry, but a subsequent social media post by the boy’s mother that references his distress during the later miles of the race.

The photo showed the boy holding a box of Pringles potato chips with the caption, “On the marathon course, Rainier knew they usually hand out Pringles around mile 20. He was struggling physically and wanted to take a break and sit every three minutes. After 7 hours, we finally got to mile 20 and only to find an abandoned table and empty boxes. He was crying and we were moving slow so I told him I’d buy him two sleeves if he kept moving. I had to promise him another sleeve to get him in the family pic at the finish line. Today I paid him off.”

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Sports medicine experts and pediatricians got wind of the boy’s marathon finish, and its unique circumstances, and published a paper in JAMA Pediatrics in October, titled “Kids on the Run—Is Marathon Running Safe for Children?”

The answer is: We’re not totally sure.

“Youth running is becoming more popular, particularly at longer distances, and the trend is ahead of the research,” says Emily Kraus, M.D., a clinical assistant professor at Stanford University, a sports medicine physician at Stanford Children’s Hospital, and the director of the the Female Athlete Science and Translational Research Program.

Kraus, a runner, was not an author on the JAMA Pediatrics paper but coauthored the 2021 youth running consensus statement published in the British Journal of Sports Medicine.

“We can’t conclude that there’s no risk or minimal risk, or a greater risk [to young children running long distances],” she tells Runner’s World.

The paper looks back at the running boom of the 1970s when several young children completed marathons; children as young as 8 years old covered the distance in 3 hours and 31 seconds. The authors note that although there were no reports of injuries or adverse events, physicians and race directors started to worry about the potential dangers of youth participation. In 1981 the New York City Marathon, then in its 11th year, instituted a minimum age requirement of 16 years old. Other races followed suit.

A 2010 paper published in the Clinical Journal of Sports Medicine looked at data from the Twin Cities Marathon from 1982 to 2007, which included 310 children aged 7 to 17 years old. The researchers found that the risk of a medical incident was about 50 percent lower in children than adults but not statistically significant. In other words: We can’t say for sure if they’re at lower risk for injury or medical problem.

“Some of the early research shows that the overall risk of competing in races is quite minimal or lower when compared to the adult running population,” Kraus says. “But the question becomes is that because the number [of children finishers] is so much smaller?”

Kraus, who treats primarily middle-school age athletes whose growth plates are still open, expresses concerns that we don’t know if marathoning at a young age will affect long-term growth and development.

“Young kids haven’t even started to initiate [certain developmental] milestones,” she says. “Athletes who are younger than 10 or 11 years old are true children. We don’t know enough to give the okay, in my opinion.”

Kraus advises against the repetitiveness of a single activity over time, like running. Instead, she encourages young athletes to try different physical activities that lend themselves to multidirectional movement, like soccer, tennis, and old-fashioned tag.

When asked to give guidance on a distance for young kids, Kraus says anything up to a 10K is “probably okay.” Ideally, she says, we would measure how far a young kid runs on any given day during free play or team sports to help guide that recommendation.

“[For children], free play at that stage of their development is more valuable in developing motor skills, agility, and hand-eye coordination,” she says.

Plus, although research is clear that healthy behaviors developed during youth sports can promote long-term physical activity and reduce the risks of diseases like diabetes, cardiovascular disease, and cancer, “sport specialization during childhood does not provide competitive advantages and is not a requirement for elite status,” the authors wrote in the JAMA Pediatrics paper.

What’s more is that youth marathon or ultramarathon running may not lead to lifelong participation in running events or long-term health benefits. The authors wrote: “Among children who participated in ultramarathons [longer than a marathon], less than 25 percent continued to do so as adults, and less than 10 percent were still running ultramarathons 30 years later.”

Most youth ultrarunners, the researchers wrote, are between 16 and 18 years old, but there are runners younger than 10 years old who have completed an ultra event.

Experts are unsure if this drop off in participation is because of overuse injury and burnout, or changes in interests. The authors go on to say that potential health benefits and risks of youth marathon running have not been compared similarly to shorter distance running or other sports.

But pediatric specialists like Kraus and the authors point out that the bigger question and concern when it comes to youth marathoning, particularly in children under 10 years old, is the intrinsic motivation of a young runner.

“Why is this child racing? Is it because they have a family of runners and they don’t want to feel left out? Is it something they deeply want to do?” Kraus asks, noting that young children likely don’t fully understand what training for and running a marathon really entails.

“If I were working with a 6-year-old, my conversation would be, ‘Do you know what [a marathon] is? Do you know what it feels like to run one mile? Or other shorter distances?’” Kraus says.

She’d then also work with families to understand why they were having a young child participate in such an extreme distance at this particular time, suggesting, instead, to use a marathon as a goal for years down the road.

Based on the available evidence, the authors developed a list of points families should consider before a young child runs a marathon or ultramarathon, in addition to assessing the physical health of the child, including:

  • Potential risks and benefits, reiterating there is limited available research
  • Determine the motivation for marathon running, with an emphasis on voluntary participation
  • Inform children that they have a right to stop at any point and will not be punished or experience negative consequences if they decide to stop
  • Discuss ways children can communicate their choice to parents and guardians
  • Monitor physical, psychological, social, and academic well-being, as well as continued commitment to marathon running during training

“For a 6- or 7-year-old who hasn’t fully captured goal-setting and follow-through, a marathon is a different type of challenge that goes beyond what they’re capable of handling,” Kraus says.

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Heather Mayer Irvine
Freelance Writer

Heather is the former food and nutrition editor for Runner’s World, the author of The Runner’s World Vegetarian Cookbook, and a seven-time marathoner with a best of 3:31—but she is most proud of her 1:32 half, 19:44 5K, and 5:33 mile. Her work has been published in The Boston Globe, Popular Mechanics, The Wall Street Journal Buy Side, Cooking Light, CNN, Glamour, The Associated Press, and