Science of preventing injury on ice -- NY Times
John
June 23, 2009
Science Takes to the Ice
By PAM BELLUCK
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.”