Motion Analysis Corporation

Preventing Ice Skating Related Injuries

The following article from the New York Times focuses on research being done at the Human Performance Laboratory at the University of Delaware in preventing injuries to ice skaters, including the development of a new ice skating boot. For these studies, a Motion Analysis Eagle Digital System was used to capture the motion of the ice skaters.

View the New York Times online article and video

 

Science Takes to the Ice

Story by Pam Belluck. Photos by Jessica Kourkounis.

NEWARK, Del. - Melissa Bulanhagui is a highly ranked figure skater, but two years ago her right ankle failed her. She sprained it twice and tore a ligament, each time during one of her favorite jumps, the triple lutz.

Other skaters have suffered similar injuries, and now science is studying why, aiming to help skaters meet the sport's physical challenges without sacrificing their health.

For one study, Ms. Bulanhagui (pronounced BULL-en-hayg-ee), 18, and other skaters tape to their shins devices called tibial accelerometers, which measure the force of the impact when skaters land a jump.

"A lot of the impacts are really high, 90 to 100 G's," said Kat Arbour, a skater turned graduate researcher at the University of Delaware. "If you hit your head that hard, I don't think you'd survive."

But she said study results suggested that the issue was not jumping itself, but how well jumps were executed. "If someone is really proficient, they seem to be able to modify their technique to decrease the impact, use muscles differently to absorb that shock," she said.

The accelerometer study is part of a flowering of research on safety and performance. And it is no coincidence that such research is growing at a time when figure skating, a year-round pursuit for competitive skaters, emphasizes athleticism and endurance more than ever before.

Adjustments to international judging guidelines in 2003 made skating "much more physically and mentally challenging," said Mitch Moyer, senior director of athlete high performance for United States Figure Skating, which is sponsoring the accelerometer study and others. Each skill in a performance now receives specific points, requiring more focus. And skaters no longer have an incentive to perform all jumps early in a program before they tire - now, jumps done later earn extra points.

"People said, 'Oh, it's an art,' but the reality is it's a very taxing sport," said Michelle Provost-Craig, associate professor of exercise physiology at the University of Delaware. "Many skaters end up with stress fractures, knee problems and hip problems at a fairly young age."

Research could inspire new training recommendations concerning issues like off-ice conditioning and limiting repetitions of jumps during practice. United States Figure Skating now has a sport sciences and medicine director, who works with scientific researchers and helps coaches monitor skaters' health more closely and pace workouts.

"Coaches are paying a lot more attention to these things," said Mr. Moyer, who said some concerns were set off by a "trend of hip issues" with skaters like the Olympic champion Tara Lipinski, whose hip injuries required surgery at 18. "I hear a lot more buzz out there - 'you need to stop jumping, you've done enough today.' "

Scientists are looking at skating from every angle - biomechanics, physics, muscle conditioning, body fat, oxygen consumption, exercise-induced asthma.

Ms. Arbour, of the University of Delaware, has skaters, wearing swimsuits and nose clips, climb into the "bod pod," an egglike capsule measuring fat and muscle composition. A "bone densitometer" analyzes bone density, which tends to increase with frequent impacts.

"If it's low, they are at risk for stress fractures in the legs and lumbar spine," she said. "If it's too high, they are at risk for osteoarthritis because the cartilage is taking a lot of shock absorption."

With Professor Provost-Craig, Ms. Arbour also outfits skaters with "a crazy dungeon thing that goes over the mouth and nose," measuring oxygen and carbon dioxide in air skaters expel.

Science is even filtering into recreational skating, with the development of synthetic ice, intended to broaden appeal and year-round interest. But most research concerns competitive skaters.

Some researchers are interested, for example, in the sport's effects on younger skaters, said Mr. Moyer, because "kids develop differently at different ages. If somebody's injured at 14, was it because of what they were doing at 9 or 10, or at 14?"

Professor Provost-Craig plans to study whether certain jumps generate such physical impact that younger skaters should delay learning them.

"A lutz might put more loading on a young skeletal developing frame than a toe loop," she said. "They may choose, especially during a growth spurt, not to teach a new jump with extensive loading characteristics."

Some research focuses on training and equipment.

James Richards, senior biomechanist for the Human Performance Laboratory at the University of Delaware, designed a skate boot to provide flexibility for pointing toes and maneuvering feet.

Current boots are stiff for support, "comparable to a cast," said Kelly Lockwood, an associate professor of physical education and kinesiology at Brock University in Ontario, preventing the ankle from absorbing enough impact.

Professor Richards's boot, hinged around the ankle, allowed flexibility but fell apart after about a month, he said. And skaters and coaches thought it unattractive.

"People were willing to give it a try if it was helping in impact and injury," Mr. Moyer said. He said that Alissa Czisny, currently the national champion, wore the boots for a while, but that she and others "became frustrated with some of the challenges."

He hopes the accelerometer study will indicate whether "one type of boot design or blade design could maybe reduce the stress load."

Professor Lockwood has studied something more rudimentary: how skate blades are sharpened. A blade's bottom is not flat, but grooved to create two edges that grip the ice. A study with the National Hockey League of groin injuries found that "more than 50 percent of them are due to skate sharpening, way too deep a hollow" in the blade's groove, which can give a player too much traction instead of allowing easy gliding, she said.

Sharpening, it turns out, is hard to do well, and sharpeners who earn respect from skaters and coaches have become scientists of sorts, too. George Knakal, a 79-year-old retired cabinetmaker turned sharpener in Norwalk, Conn., pays zealous attention to several factors, including the concavity of the blade.

"For a new skater, I make it nearly flat because a little kid is very awkward and you want to give them something that will slip so when they fall they don't get hurt," he said.

Training when not on ice is another matter altogether, and theories differ about what off-ice conditioning is best.

"It's a sport where you're doing contradictory things," said Deborah King, associate professor of exercise and sport sciences at Ithaca College. "Running or cycling or stair-stepping to improve aerobic capacity - does that translate really well on the ice, or is it better to do something more specific to skating? Do you need a lot of strength training in the gym or training to do the motion while rotating?"

Professor Provost-Craig said skaters should not "bulk up" from strength training because "if they increase girth of shoulders, hips or thighs, that's going to decrease rotational spin."

One recent invention for off-ice training is a block of wood topped with rubber, slanted to approximate angles of skaters' blades on ice. Wearing skates on the block, skaters assume different positions.

"It will freeze-frame any on-ice technique and mimic as close as you possibly can the requirements for balance, that sensation of shifting your weight against momentum," said its creator, David Lipetz, a physical therapist who is trying to get coaches and skaters to use the device.

Professor Provost-Craig's oxygen mask readings help gauge the aerobic conditioning skaters need, measuring their "VO2 max," she said, "oxygen their muscles are consuming" as they skate to increasingly fast music. More is better, improving endurance, for example, to do jumps later in performance.

Professor King analyzed jumps in a different way. Studying Olympic skaters, she determined that on triple jumps, they went no higher than on double or single jumps - rather, they rotated faster by pulling in their arms, making their bodies compact.

That guides one of Professor Richards's more elaborate projects. With sophisticated motion-capturing cameras and computer programs, he mimics skaters' positions during jumps and calibrates the effect of altering angles of the head, torso, arm and leg.

Consider Emma Phibbs, a 22-year-old pairs skater looking to make a comeback after scaling back skating in college. Recently, researchers affixed 38 quarter-size stickers - made from golf ball markers, children's alphabet beads and reflective tape - all over Ms. Phibbs's body and sent her skating.

Doing triple toe loops and double axels, she wobbled on some landings, occasionally falling.

Rink-side, Professor Richards's computer displayed an outline of Ms. Phibbs, construed from the reflective stickers.

"Her left arm is higher than her right arm - she's got to lean to one side to compensate," he said. Breathless from jumping, Ms. Phibbs reviewed the computer images.

"With my elbow and my trunk being off, my landing will be off and I'll two-foot it," she said. Then Tom Kepple, a researcher, displayed an animated avatar of Ms. Phibbs's jump attempts, calculating that she rotated only 314 degrees. With a few keystrokes, he tucked the left arm in.

"That adds 40 degrees more of revolution," he said. "If she brought the left leg in a little straighter? You pick up 10 or 15 degrees rotation. But if she brings her leg in too much, the jump goes bad."

Such analysis works "not just for technique, but also for injury prevention," Mr. Moyer said. "You can see what your result is going to be before you try it."

That could make a difference for skaters who must train aggressively enough to master moves but not aggressively enough to hurt themselves.

"I always tell my athletes that they're going to be injured at some point in their career, so it's more about management of that and also trying to have a minor injury instead of a major injury," said Tom Zakrajsek, who coaches top skaters. "I have certain jump limitations and restrictions - I always have to pull back my skaters from repetition of jumping."

In Delaware, after the scientists opined on Ms. Phibbs's body position, she got back on the ice.

"I focused on keeping my elbow down, and my landings were a lot more solid," she said. "It definitely proved itself."

A version of this article appeared in print on June 23, 2009, on page D1 of the New York edition.