Force of flight: BYU skating device measures impact of jumps and landings

When a figure skater lands a jump, she lands with about five to eight times
her bodyweight in force. Those high magnitude forces are due to
the fact that she’s moving really quickly. She’s landing from a height. She doesn’t
have time to absorb those forces through the body, so
that force just gets transmitted straight from the ice up through her lower
extremities up to the back. When we look at the high speed video, we can see not only how is the body absorbing
the forces but also how the body works to generate these forces. A skater may do
between 50 and 60 jumps on a day where they’re preparing for
competition. A lot of skaters by the time they’re 20, 30, 40, have double
hip replacements from all the pounding and the damaged. You just feel
old really young. They have a lot of force that they’re landing with over and over again and this contributes
to overuse injuries. So we’ve been designing a device that we can attached to a figure
skate. It’ll be unobtrusive to the skater, and it will measure the impact
forces on takeoff and landing. This is really the first time that
actual forces are measured on ice. In the lab testing, we’ve been having a skater jump onto a
force plate. This is really set up to get some baseline data initially. Wer’e collecting data from three
different spots: in the front, in the middle, and on the back part of the skate, and that’s what the six different lines
are we see on the screen. Right here where the large lines are is where she actually impacts. So we want to be able to
measure forces as small as six pounds and as great
as a thousand pounds. When someone jumps
on the ice, those tensions compress about one millionth of an inch. That’s about one thousandth of the width a
human hair. So very, very small compressions. It’s a whole body workout. You can see just how much
strength it really takes to do the skill. When you do a figure skating jump
landing, you always land on a toe and then rock back to the heel.
That toe impact is not where the highest impacts are. You
get a pretty high impact there. Then you rock back to the heel, and
that’s where you get up to 5 to 8 times body weight. That happens
really quickly. It’s within 50 to 125 milliseconds. Comparing that to
running where you land with maybe two to three times your body weight in each step you take, we can see that these
magnitudes are really high. The skating route provides very little
protection. In general, coaches and skaters may not
talk about landing forces all that often. It’s just kind of a necessary evil. This
is what happens. You know you land a jump, and you have these
high magnitude forces. U.S. figure skating is
really interested in this research because they
want to be able to keep skaters healthy. They
want to be able to keep their elite skaters performing at a
high level, and then keep skating safe as a sport for any participant.

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