Too young to run? Kids who run races alongside adults are getting a lot of attention--but not all of it's good. Are these young runners going too far?

• Author: Modigliani, Laura
• Position: Heather Welsch - Cover story

Heather Welsch is excited to run her first marathon later this month. She won't be leading the pack during the 26.2-mile race near Austin, Texas, but she's sure to get plenty of attention. Heather is only 11 years old.

The sixth- grader from Alvin, Texas, is no stranger to running. She has been competing since she was 8. Heather races and trains with her 13-year-old sister, Kaytlynn, who has already run in three marathons.

Since 2010, the sisters have completed nearly 200 endurance races. Most of them range from about 3 miles to 13 miles. The girls are often the youngest runners on the course. They're used to sprinting past adults who are 20 years older.

"Sometimes they get mad that we're beating them," Heather says.

Safety Concerns

Heather and Kaytlynn say their goal is to run in the Olympics one day. Their dad is their biggest fan, always cheering them on from the sidelines. But not everyone is so thrilled about kids competing in endurance races.

Many people have questioned whether or not these strenuous events are safe for young runners like the Welsch sisters. There doesn't seem to be a clear answer, though, even among doctors. Not much research exists on the effects of long-distance running on kids. Still, some doctors worry about the possible risks.

"A full marathon is [rough] for almost anybody. It's a lot of stress on your bones [and] muscles," says Dr. Jeff Hanway. He works at Children's National Medical Center in Washington, D.C.

Kaytlynn and Heather compete nearly every weekend, often running back-to-back races on Saturday and Sunday. That makes doctors like Hanway concerned that they aren't taking enough time to rest and recover.

"I think you start getting into danger when you're training all week long and you're doing a race every weekend," he says.

Kids on the Run

Many young long-distance runners say it's unfair to criticize them. They argue that kids compete in other physically demanding sports, like football and gymnastics.

The Welsch sisters also point out that some kids don't exercise at all. The girls are regularly checked by their own doctors, who say they're in good health. Hanway adds that running can have positive effects on kids, as long as they don't overdo it. Kaytlynn and Heather say running makes them stronger and mentally tougher.

"[Running] makes me feel so energetic," Kaytlynn explains. "It helps me feel like I'm going to be something when I grow up."

Going the Distance

Age requirements differ in each...