Should Kids Run Long?

Can too many miles ruin young runners?

June 26, 2011

Mark Hadley has heard it all. The father of junior high phenom Alana, who ran 40–50 miles per week as a 12-year-old and is now up to 70 –75 per week as a 14-year-old, has been told that she'll damage her joints, destroy her health, wear out, burn out. One local coach even said, "That's it. You've ruined her. She won't grow any more running all those miles."

When we published a brief profile of Hadley in our September 2010 issue, we saw similar reactions. Well-meaning readers asked whether she wasn't putting her health, not to mention her athletic ability, at risk. Wrote one, "I would be surprised if over or anywhere near 50 miles per week for a 13-year-old girl is not having a debilitating effect on her growth and physiology."

While not questioning the concern and good intent of these reactions, we wondered whether they had any scientific validity. There is, of course, the example of African youth, who, while they may not run as much as some legends suggest, put in far more miles, simply as transportation, than most American youth even in aggressive training programs. Elite coach Joe Vigil often estimates that, by the time they reach high school, Kenyan youth have run as much as 10,000 miles more than their American counterparts. A Scandinavian researcher, Bengt Saltin, found in a 1995 study that active Kenyan school children covered on average 8–12K a day. That's a weekly total of 35–50 miles.

Are American kids different than Kenyan kids, we wondered? How much can kids safely run? Or might this concern for kids' health be more like the notion, 100 years ago, that marathons would make you "go stale" and break down your health, or 30 years ago that women would damage their reproductive organs by running long, or even the persistent myth that running will ruin your knees and give you arthritis?


The short answer to that is yes. "It's basically an urban legend," says Cathy Fieseler, M.D., practicing sports physician on the board of directors of the American Medical Athletic Association. While you won't find controlled studies on this, as you can't put a group at health risk for science, Fieseler maintains, "You'll find no data that kids will tear up ligaments, destroy cartilage or damage growth plates with high mileage. You don't need to put a top limit on it."

William Roberts, M.D., medical advisor for the Twin Cities Marathon, has conducted several studies on young marathoners, a self-selected group of young high-mileage runners, and has come to the same conclusion. "Kids and mileage basically makes us nervous," Roberts says, "but from all I've found, there is no harm being done; they are not getting hurt. If it is their choice, keep doing it."

A study on overuse injuries and burnout in child athletes published in the June 2007 issue of Pediatrics points out, "Endurance athletic events (triathlons, marathons, and half marathons) are becoming more popular in the United States, and legitimate concerns have been raised for the safety of youth participating in these events." The report concludes, "There is, at present, no scientific evidence that supports or refutes the safety of children who participate in marathons. There are no recorded data on injuries sustained by children who run marathons. … Ultimately, there is no reason to disallow participation of a young athlete in a properly run marathon as long as the athlete enjoys the activity and is asymptomatic."

Tim Noakes, M.D., professor of exercise and sports science at the University of Cape Town, concurs, stating in his Lore of Running, "It is important to stress, however, that there is no evidence for any negative physiological effects of intensive training by itself in the prepubertal period." He goes on to say, "There is no evidence that either children or adults can train themselves to the point where they suffer lasting physical impairment," and, "Gifted young runners [6-to 10-year-olds], who choose to run these distances [excess of 8–10K] are at no greater risk of an unfavorable outcome or injury than are adults completing the same distances under the same environmental conditions."

Elite coach Brad Hudson, who famously ran mega-miles as a youth (100 miles per week as a freshman in high school, up to 140/week before he graduated), agrees strongly that high miles won't hurt a young runner. "I was extreme," Hudson admits, "but I was self-motivated. I ran a lot because I was a crazy kid. The biggest factor is that they have to be enjoying themselves. But if they are enjoying themselves being pushed, that's OK." Hudson didn't suffer from his early miles, going on to garner All-American status in the 10,000m and eighth in the NCAA cross country championships while at Oregon, and running a 2:13 marathon PR post-collegiately.

In the case of Hadley, she's grown 6 inches in the three years since the coach's dire warning that she'd stunted her growth. In her eight years of running consistently, she's never had a running injury. And, on the eve of the early February USATF Cross Country Championships when I interviewed her, she was dancing in circles in anticipation of getting to run against some of her heroes the next day: "I get to race Aisling! [Cuffe]" she blurted, throwing up her fists in glee, when asked if she knew who else would be in her race. No sign of burnout yet.