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 timesher bodyweight in force. Those high magnitude forces are due tothe fact that she's moving really quickly. She's landing from a height. She doesn'thave time to absorb those forces through the body, sothat force just gets transmitted straight from the ice up through her lowerextremities up to the back. When we look at the high speed tutorial, we can see not only how is the body absorbingthe forces but also how the body works
to generate these forces. A skater may dobetween 50 and 60 jumps on a day where they're preparing forcompetition. A lot of skaters by the time they're 20, 30, 40, have doublehip replacements from all the pounding and the damaged. You just feelold really young. They have a lot of force that they're landing with over and over again and this contributesto 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 thatactual forces are measured on ice. In the lab testing, we've been having a skater jump onto aforce plate. This is really set up to get some baseline data initially. Wer'e collecting data from threedifferent spots: in the front, in the middle, and on the back part of the skate, and that's what the six different linesare 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 jumplanding, you always land on a toe
and then rock back to the heel.That toe impact is not where the highest impacts are. Youget 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 happensreally quickly. It's within 50 to 125 milliseconds. Comparing that torunning where you land with maybe two to three times your body weight in each step you take, we can see that thesemagnitudes are really high. The skating route provides very littleprotection.
In general, coaches and skaters may nottalk about landing forces all that often. It's just kind of a necessary evil. Thisis 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 ahigh level, and then keep skating safe as a sport for any participant.
Water Sports How to Get Air on a Wakeboard
Hi, I'm Greg Lawrence, with Lake Lessons,and I'm here to show you how to jump on a wakeboard. First of all, there's several conceptsyou need to understand. When jumping a wakeboard, it's not done mostly by bending your legs,and jumping as you would, a jump shot. It's actually done by the edge of the board. Youwant to use the edge of your board for your power, all the way up the wake, and then,while slightly pulling the handle in off the top of the wake, to keep your momentum goingforward with the boat. You want to extend your legs slightly for pressure, so it's notlike a jump shot, in which you would push down with your toes. In fact, you want topush with your heels only. In the air, you
want to remain as calm as possible, and youwant to land, while crushing your knees, just like there. Now, when you're first startingto learn how to do a jump, you only want to take a small cut outside the wake, and doa small controlled cut, all the way up through the wake, a One Wake Jump. This is going toget you used to not only releasing from the wake correctly, but also landing, and cushioningyour landing. As you get better with that One Wake Jump, you're going to want to addmore and more edge. Now, that's an important point. As you'll see here, Ross is using aprogressive edge, as he edges into the wake. That progressive edge means he starts veryeasy at the beginning, and he continues to
add edge, so that he's on his most aggressiveedge, as he goes up through the top of the wake, harnessing all the power of the water,rushing underneath the board, at twenty plus miles an hour. I'm Greg Lawrence, and that'show you jump on a wakeboard.