Although gym uniforms are a schoolhouse staple, the only guideline children usually get on footwear is to make sure it won't mark the floor.
But with sports-related injuries on the rise among this generation of active kids, a UNLV researcher wants to change that. Kinesiology professor John Mercer's research could influence the way sneakers are designed for children.
"There's not a lot of shoe development for kids because they go through them so fast," Mercer said. "But kids just aren't miniature adults. I think it's hard to take a shoe designed around an adult and reduce it down to kids."
Mercer received a grant from the National Athletic Trainers Association to study the impact to children's bodies during running, and how it affects their bodies differently from adults. His subjects, all 9 to 12 years old, have been going through their paces on treadmills in Mercer's lab since this summer.
The program draws on the findings of Mercer's past research into adult impact characteristics — the effects on the body of different running surfaces, shoes, and conditions. "Every time a foot hits the ground, it's a collision," Mercer said. "One of the reasons runners get hurt is because running is an impact sport, and impacts do damage."
Impacts also do some good, such as building bone density, but the trick is finding the happy medium before an overuse injury occurs. And that's where the data on children is lacking, Mercer said. As more kids participate in organized sports — most of which, like soccer, involve running — more of them are showing up with tendonitis and stress fractures.
It's not only the impact of feet on pavement that causes trouble, Mercer said. More likely, the culprit is the high number of times a foot slams into the ground, with the force of up to two times the body's weight behind it.
"It's a very short applied force, but if you count the footsteps during a 30-minute run, that's 2,500 to 3,000 collisions," Mercer said. "It's quite a bit of load on the body."
Running injuries have been Mercer's primary research interest. He was an avid runner himself until he was sidelined by overuse in the form of rheumatoid arthritis.
Mercer said he hopes to submit his initial findings for publication by the end of the year.
Although his work is still in the early stages, Mercer thinks organized sports play a role in the increase in overuse injuries. Sports leagues are more prevalent now than in previous generations, and many kids participate in something every season. Few kids are into running as their main activity, but Mercer said many middle-schoolers at least have to run a mile for P.E. class.
Each youngster in the study plays an organized sport, Mercer said, but the only requirement for participation was a willingness to spend time on the treadmill. Two of his subjects are his own sons, ages 9 and 12. (The older boy started playing flag football this year, while the younger son is into scuba and springboard diving.)
"Kids are just different. They respond differently to instructions, and they run differently in the lab. We're finding some unique challenges that we didn't foresee," Mercer said. "It's neat for them because they are part of a research study, but on the other hand it's weird for them — we're putting instruments on their heads and legs that are wired to a computer."
Children in this age group are also beginning to learn physical fitness habits that will probably last a lifetime, Mercer said. And footwear is critical to making exercise enjoyable — if their shoes are causing problems, they might develop negative attitudes toward physical activity.
Just as car seats and bike helmets have become childhood necessities, Mercer hopes his work will eventually lead to standards that parents can follow when shoe shopping for their kids — something a little more reliable than the classic thumb-on-the-toe test.
