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Tuesday, September 21, 2010
Updated: September 29, 2:40 PM ET
Thinkers, Part 7: Rick Greenwald

"They'd go up in the air and rotate and then hit their heads, but in this case, they were smacking them in halfpipes, where it was ice," says Ph.D Rick Greenwald.

[Editor's note: This story is the final part of a seven-part series on the ski industry's most innovative thinkers and the original ideas that drive the sport forward. Be sure to read up on the previous installments.]

Part 1: Tom Wallisch Part 2: Snow ScientistPart 3: Katal Innovations

Part 4: Eric PollardPart 5: Snow forecasterPart 6: Hans SmithPart 7: Rick Greenwald

Rick Greenwald knows ski injuries like Einstein knew physics. The 46-year-old Norwich, Vt., resident holds a Ph.D in orthopedic biomechanics ("the study of how the body moves, gets hurt and how it heals," he explains); wrote his thesis on knee injuries among skiers; and in 2005, he was elected president of the International Society for Skiing Safety -- a worldwide group of researchers, engineers and medical doctors. Lately, Greenwald, a skier for 33 years, has been working to unlock the mysteries of brain trauma in athletes, one of the most polarizing topics in sports. The founder of Simbex, a cutting-edge research and engineering firm in Lebanon, N.H., Greenwald spoke to us about the parallels between football and skiing, why parents (like him) should be worried and the helmet-sensor system that is changing what we know about head injuries.

I lived in Park City in the early '90s and hung out with the U.S. Freestyle Aerials Team. I noticed there were a number of people on the team who didn't seem right, if you will. So I started talking to them and got the impression that part of their sport involved hitting their heads on the snow. I asked them what kind of helmets they used, and they were using kayaking helmets because that's who would sponsor them. So I went up and watched them and counted how often they hit their heads. And I thought, that's quite a bit.

A Giro helmet outfitted with the new Simbex sensor system.

I spoke with a colleague who was the director of sports science for the U.S. Olympic Committee. He and I got a research grant from the National Operating Committee on Standards in Athletic Equipment and the USOC, and they funded a study for us to look at how often and how hard the athletes hit their heads. What we found was they hit their head, on average, one out of every six or seven times they jumped.

I'm a biomedical engineer, and I have a lot of experience building measurement and sensor technologies. So we took the best technology of the day, which fit on the outside of the helmet. We quickly learned that the readings were interesting, but what we were really measuring was the acceleration of the helmet, not the head.

Fast forward a number of years. In 2000, I moved back to New Hampshire and started Simbex. One of our first projects was to apply for a product-development grant from the National Institutes of Health. We used that to create what we call the Head Impact Telemetry, or HIT, system for monitoring head accelerations in helmeted sports, which no one had really measured in the field. The technology was initially developed for football helmets, and we've also studied head impacts in hockey, boxing, soccer, snowboarding and the military.

The system includes six sensors that are isolated from the helmet shell and the foam padding, and they rest with little foam springs against the head. They're the same sensors that trigger the airbags in your car.

Rick Greenwald, president of the International Society for Skiing Safety.

In that same period of time in skiing, all of a sudden we had something that had always existed but now became mainstream: catching air. I stood and watched, and it was different from what I'd seen 20 years ago: they'd go up in the air and rotate and then hit their heads, but in this case, they were smacking them in halfpipes, where it was ice, and in terrain parks, where there are rails and tables and hard surfaces.

Fast forward again five years. There's a local ski area called Whaleback [in New Hampshire] run by a former Olympian, Evan Dybvig, that's focused on freestyle skiing. So I approached him and we instrumented some Giro helmets on skiers at his area. Together with a pediatric neurosurgeon at Dartmouth, Susan Durham, we did a study over two years to try and understand how often and how hard the kids training at Whaleback were hitting their heads.

We found they were hitting their heads one to two times per hour. We don't know what that means in terms of injury potential; we don't know if it's bad or good, and the magnitude of those impacts is generally low. But once in a while, you smack your head pretty hard.

One of the problems with that is kids are unlikely to report their injury if they don't feel well, and they're continuing to do these tricks while they might have signs and symptoms of a brain injury.

We're calculating the linear and rotational acceleration of the head during impact. It's not diagnostic; it doesn't tell you you have a brain injury. But we have a pager system that's part of our commercial football helmet system, and when you go over a certain threshold, we send a page to the medical staff that says, hey, this person should be looked at.

The system is not commercially available in skiing because there's no defined need for it yet; no one's clamoring for it.

We don't know exactly what causes a concussion. That's what all our research is about. As that information becomes available, it can be shared with manufacturers of sports helmets so they can improve their product for the public.

There are major issues of whether ski helmets can prevent death when you're going very fast. I think the general answer is no; the research has shown that. The average skier is going 18-20 miles an hour. If you crash into a tree at that speed, the helmet isn't really designed for that energy; it would have to be too big and too heavy.

I think there's a big problem with making a law requiring people to wear helmets because then the mountains have to spend a lot of money to enforce that law. And I don't know if the industry has the financial resources to do that. Plus, part of skiing is the freedom of expression.

By and large, when you look at the injury rate in skiing, it's relatively modest. Usually it's a significant injury -- you blow out your knee, you break your wrist, you hit your head, lacerations. But the sport's overall injury rate is actually pretty low.