Archive for the ‘Vertical jump’ Category

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Figure Skating Jumps – A Review of Minimum Air Times (Trevor Laak)

July 2, 2014

With the prevalence of low cost video analysis apps on mobile phones and tablet computers, video analysis of figure skating jumps is within reach of EVERY coach and skater. Past research into minimum air times for each jump can now be used by all figure skating participants to help assess skater progress and minimize injuries.

To my knowledge, no formal publication of jump minimum air times has yet been made. However, a large number of researchers including this author have compiled statistics on minimum air times that should provide helpful guidelines for those interested.

I have received a huge number of requests for this information so I hope this post addresses the interest in this topic.

 

Why Minimum Air Times Are Important

Knowledge of minimum air times is important to coaches because it provides a relatively clear way of assessing a skater’s athletic progress and technical progress with any given jump. If a skater is matching or exceeding the minimum air time for the jump and has solid technique and an appropriate body type, they should be able to get close to full rotation of the jump under ideal conditions.

Air time information serves two important and related purposes in the development of figure skating jumps.

1. It reduces the pressure on skaters to complete elements that they physically have no chance of completing, and

2. It dramatically minimizes injuries from attempting jumps a skater is not yet ready to attempt.

Skaters have historically been under extreme pressure to land more advanced jumps at younger and younger ages. As the sport progresses technically, this pressure is only continuing to grow.

How many skaters feel guilty about not landing their double axel (or any jump) after working on it for months or years? Skaters often feel that they are letting their parents and coaches down and they often experience extreme frustration at themselves for not learning a new jump sooner.

But minimum air time measurements can help to reduce this guilt and frustration. If a skater knows she or he is not jumping high enough to land a jump cleanly, the focus turns to solving that problem rather than remaining fixated on just landing the jump.

Similarly, coaches can help their skaters dramatically reduce injuries by knowing their skaters’ air times and not expecting or demanding that the skater stand up and land the jump when they are simply not ready. It then becomes the coach’s job to help the skater optimize jump technique and develop the necessary jump height through off-ice training.

The days of repeated futile jump attempts are over, or at least they should be. In this day and age, no coach should continue to apply the just-stand-up-and-land-it mentality without knowing air times.

How These Numbers Were Generated

The minimum air time numbers for each of the major figure skating jumps provided below were compiled from measurements of many jumps over a long period of time. By measuring air time on as many jumps as possible over a period of many years, certain air times stand out for each jump.

Some of the measurements were made on practice jumps videoed directly by a coach or skating parent while others are a result of digitizing televised broadcasts of competitions or other events of elite skaters. Historically, a televised skating competition or event could be recorded and then digitized to provide model jumps for analysis.

 

Caution With The Numbers

It should be noted that attaining minimum air time does not automatically mean a skater should be able to land a given jump. Minimum air times are typically only possible by skaters with extremely efficient technique and an optimal body type.

Skater body type plays a big role as smaller and thinner skaters typically have an advantage for faster rotation. Even this is an over-generalization because some tall skaters can rotate very fast, but as a general rule, it is small and thin skaters that these minimum air time numbers were generated from.

Thus, larger skaters or those that have a more substantial frame will almost always need more than the minimum air times listed below.

Rotation rates are obviously also affected by take-off mechanics. This means that a skater may jump higher than the minimum air time but lack the ability to create enough rotational energy on the take-off to spin fast enough in the air, even with a perfect air position and body type.

Coaches should strive to help their skaters optimize jump take-off technique and air position. Jump height is a result of jump technique as well, but overall skater athleticism appears to have a very strong influence on the ability to jump high. The development of athleticism is probably best attained through significant focus on off-ice training methods.

For more information about jump technique or off-ice training methods, please visit iCoachSkating.com. That website is committed to providing the best educational information on the nuts and bolts of how to figure skate.  It has literally hundreds of videos on jump technique from some of the world’s best coaches.

 

How to Measure Air Time

For accuracy, it’s important to maintain correct measurement methods. When analyzing jump air time, the measurement should be made from the first video frame a skater’s blade is in the air to the first frame the skater’s blade touches the ice.

It is NOT accurate to measure from the last frame on the ice to the first frame back on the ice. This measurement method will result in air time measurement that are too large. The details of this are beyond the scope of this article and will be provided elsewhere.

Simply use first-frame-off-the-ice to first-frame-on-the-ice and you’ll be fine. Most apps don’t have a way to reset the clock to zero on the first frame in the air, so record the time at the first frame in the air and the first frame back on the ice and subtract to get air time.

 

Shout Out to Christy Krall

At the 2011 PSA World Conference in Dallas, TX, World and Olympic figure skating coach and video analysis expert Christy Krall gave a presentation in which she provided insights about minimum air times for all the main jumps from double loop through triple lutz. To my knowledge, Christy has not published these findings elsewhere, partly since she uses these only as guidelines and there may be some skaters with successful jumps at lower air times.

I am publishing both Christy’s numbers and my own observations here for your reference. But remember, these numbers only represent our experience and are not absolute. Christy provided numbers for both male and female skaters (female/male). Air times are provided in seconds.

Jump                     Trevor                   Christy
Abbrev.               Air Time                Air Time

1A                           0.30

2S                           0.30

2T                           0.30

2Lo                         0.33                        0.35

2F                           0.35                        0.35

2Lz                          0.35                        0.35+/0.36

2A                           0.45                        0.45/0.47-0.51

3S                           0.47                        0.47/0.48-0.51

3T                           0.48                        0.47+/0.48-0.51

3Lo                         0.50                        0.51/0.52-0.53

3F                           0.53                        0.53+/0.56-0.58

3Lz                          0.53                        0.53+/0.56-0.58

3A                           0.60-0.62

4S                           0.63

4T                           0.63

 

These Minimums Are Not Absolute

Again, these numbers are not absolute. For example, I’ve seen 2 double axels with an air time of only 0.43 seconds. One was during practice sessions with a young skater in Korea with extremely efficient technique and a very thin body type and the other was off video taken by another coach of a similar Japanese skater who eventually became a World Champion. I do not consider 0.43 seconds to be a reasonable minimum air time for double axel because my experience shows that only an extremely rare and talented skater can pull it off.

Similarly, Sasha Cohen was capable of landing a quad salchow with just 0.60 seconds of air time. This astonishing feat of optimization may represent the absolute lowest possible air time for quad salchow, but most quad salchows are being landed with air times of 0.65 and higher. A significant number of skaters have landed the quad salchow at 0.63 seconds which is why it’s listed on the chart as the “reasonable” minimum.

When we use minimum air times with our skaters, we want them to target a reasonable number for their body type. So based on the skater’s body type and my experience, I may shift the numbers slightly so they have a more appropriate air time goal. We want skaters focused on meeting and exceeding air times that should provide success.

I hope this article is helpful. I did not ask Christy for permission to publish her air time numbers here but felt that her work deserves your awareness. Her groundbreaking research was a starting point for my own observations and this article would not be possible without her contributions.

 

Final Note

To get an idea of what these air times mean in regards to actual jump height, please see my previous post comparing air times with projectile height (Are Figure Skaters Projectiles?).  Sometimes it’s helpful for skaters to understand how much more jump height they need. Knowing that your double axel air time is 0.40 seconds and you need 0.45 seconds is somewhat abstract. But knowing you need to generate an additional 2 inches of jump height is very tangible to most skaters.

Please leave a comment and let me know if this article was beneficial.

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U.S. Junior Figure Skating Championships

December 8, 2007

Last week I went to “Junior Nationals.”  The skating was pretty impressive by our up and coming skaters.  Lots of athletic and artistic skaters with one great performance after another.  It was great to see.

I made the trip mainly to promote my new website which will be revealed very soonThe website will be a place for skating coaches to interact online.  It will also provide “featured content” much like the streaming video of Dartfish jump analyses at Skating Coach Quiz.

The trip was a great success in terms of meeting a lot of influential people in skating.  I got to meet Carol Rossignol, the Education and Accreditation Director of the PSA.  I also met and chatted with Nancy Kerrigan who was there doing live internet broadcasts for Ice Network.  Coach Peter Oppegard won the Vertical Jump Contest with a jump of 23.5 inches.  He also said he might be willing to provide some content for my website.

Getting back to the Vertical Jump Contest…  I was at Junior Nationals as a staff member of Audrey Weisiger’s Grassroots to Champions (G2C).  I spent most of the competition manning the G2C booth and hanging out with Sheila Thelen of Champion Cords.  Sheila’s a blast!  As part of G2C’s commitment to developing skaters and coaches, we held a Vertical Jump Contest for everyone at the competition.

The highest vertical jump off two feet by a lady was 18.5 inches by a 13 year old.  As I said above, Peter Oppegard won the guy’s title.  The most spectacular jump was an 18 inch vertical jump by a 10 year old girl.  It was incredible!  Probably less than 1 in 10,000 ten year old girls can jump that high.

On Sunday (12/2/07), I helped Audrey Weisiger with a G2C Seminar.  I’ve attended one of her seminars before but this was my first one as part of Audrey’s team.  I did pole harness and computer video analysis as well as helped with off-ice harness testing.  It was a great experience and I look forward to doing more seminars with Audrey.

When I got home to Wisconsin, it took me 30 minutes to dig my car out of an ice drift.  Ahh…winter.

Trevor

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Initial Test Of Vertical Jump Measurement Methods

November 18, 2007

Continuing the discussion from my last post (Double Axel Barrier), I’ve been able to run two tests so far with mixed results.  Recall that I’m trying to determine if flight time measurements made using video analysis software such as Dartfish or Pro-Trainer (a low cost Dartfish substitute) can be used to estimate jump height.

As stated in previous posts, sufficient flight time is a critical component for figure skating jumps.  For example, in order to get enough rotation to land a clean double axel, the minimum flight time needs to be about 0.45 seconds.  Based on some physics calculations (basic projectile motion), I’ve been estimating the required height at 10.5 inches (0.467 seconds).

My ultimate goal is to see what percentage of the female population is physically capable of landing a double axel.  To do that I’ll need to correlate the flight times with standard vertical jump statistical data.

The first part of the test is as follows:
1. Skater stands next to wall and reaches up and makes a mark with one finger (using chalk or washable marker).
2. Skater stands on tip toes near the wall and makes another mark with same finger.
3. Then skater fully bends and jumps up off two feet as high as possible, slapping the wall and making another mark.
4. Step 3 is repeated until skater has a consistent pattern on the wall of maximum jump height.
5. The standing mark is considered the baseline.  The tip toe mark and the maximum jump height are measured from the baseline.

That gives us our “standard” vertical jump measurement.  This is the most common method used for measuring vertical jump.  Statistical data is available based on this measurement method as discussed in a recent post.  (The tip toe data is necessary for correlating with flight times and is not part of the standard test or available statistical data.)

Next, the video method is used.  For the video method, the capture software is turned on and:
1. The skater jumps multiple times facing sideways to the camera.
2. The skater jumps multiple times off one foot, using a natural “leg through and lift” technique.
3. The capture is stopped and the flight time for all the jumps is found.  (As discussed in post Are Figure Skater’s Projectiles?, the flight time is measured from the first frame the foot completely leaves the ground until the first frame when the foot touches the ground).

I performed this test with 2 skaters.

Skater A:
Baseline to tip toes:  2.9 inches
Maximum vertical jump off two feet at wall:  10.5 inches
Maximum flight time off two feel on video:  0.450 seconds (video shows flat footed landing)
  Corresponding jump height estimate from video:  9.8 inches
Maximum flight time off one foot on video:  0.351 seconds
  Corresponding jump height estimate from video:  5.9 inches

Skater B:
Baseline to tip toes:  3.1 inches
Maximum vertical jump off two feet at wall:  13.4 inches
Maximum flight time off two feel on video:  0.450 seconds (video shows flat footed landing)
  Corresponding jump height estimate from video:  9.8 inches
Maximum flight time off one foot on video:  0.450 seconds
  Corresponding jump height estimate from video:  9.8 inches

These results are clearly not conclusive.  Each skater only made three attempts for each measurement and the measurements were not always tightly clustered.  For example, Skater A had two foot flight times of 0.417, 0.451, and 0.433 seconds while Skater B had two foot flight times of 0.450, 0.434, and 0.451 seconds.  Skater A had one foot flight times of 0.317, 0.334, and 0.351 seconds while Skater B had two foot flight times of 0.400, and 0.450 seconds.

In future tests, each skater will perform more attempts to get a better estimate of the maximum.  When I have more data,  I’ll see if I can correlate the results and add in factors for take-off from tip toes and landing flat footed.

Also note, that some skaters will be able to jump just as high (or even higher) off one leg versus two, while other skaters clearly lose significant height jumping off only one leg.

I’m not sure this will be useful to you yet, but it just keeps you up to date on some of my testing.

Trevor