Why Can't Us Kids Run a Marathon?

Some people cheered and some people raged when a 6-year-old recently ran the Flying Pig Marathon. ”Why can’t we run a marathon?” say some kids that love running. “Is it safe for kids to run a marathon?” ask their parents. 

I decided to research the official age requirements for 20 of the top marathons in the world. I also asked the race directors of those marathons what they think about kids running marathons. Here is what I learned.

Age requirements for marathons vary. Most marathons require runners to be either 16 or 18 years old. Some marathons don’t have an age restriction, and some have only recommendations. Of the races polled, the Honolulu Marathon had the lowest age restriction of 7 years old and the Tokyo Marathon had the highest age restriction of 19 years old. The Marine Corps Marathon age limit is 14 years old. Some marathons have shorter races for younger runners.

Some race directors told me that the age when a kid can run a marathon depends on the kid and their own health. Some directors said that it depends on what the parents think. Other directors said that they worked with a health agency or sports governing body to make their age rules. Two more directors said that a kid should not run a marathon if they are still growing.

The age requirements for marathons are conflicting, so I asked my pediatrician, Dr. Mark Meyers, about kids running marathons.

“Kids are not miniature adults,” Dr. Meyers says. "Kids' bodies are different when they are physically active. Kids produce more body heat than adults, and they do not cool themselves as well as adults." This means that they are at greater risk for serious heat illness while training for—or running in—a marathon.

"Kids have less aerobic capability than adults and can’t really improve their aerobic capability until puberty," Dr. Meyers adds. This impacts our ability to run the full distance of a marathon.

Dr. Meyers also points out that training for a marathon can be harsh on all bodies. And, compared to adults, kids have less bone density and less-formed ligaments, so this type of overtraining can lead to fractures and broken growth plates.

Kids at ages 12 to 14 are specifically at risk for all types of running injuries because it is a “period of great biologic change.” It is also important to know that girls are at higher risk for running-related injuries than boys during this time.

The American Academy of Pediatrics has not put out a policy statement on kids running since the early 1990s. The most recent information was a consensus statement published in the British Journal of Sports Medicine in 2021. The authors of the consensus statement are a group of people interested in running who want to figure out the safest way to help youth runners. They looked at health journals and studies of kids running and they said that the science is incomplete. Current recommendations on distances for youth runners are opinion based. Here is a typical example of such recommendations:

One study of marathon runners ages 7 to 17 years old said that many experts are guessing that long distance running is not safe for kids because there is insufficient data.

I think there should be more study of the effects of kids' running. It seems important. Until then, I’ll do what Dr. Meyers says and enjoy running one mile.