Freestyle Skiing Aerials

Freestyle Skiing Aerials is the springboard diving of the Winter Olympics. Athletes complete huge back flips and twists after taking off from a ramp with takeoff angles ranging from 60 to 70 degrees.

Athletes are judged on their take off, the height attained during their trick, the control, form and body position during the trick, and how they land and ski out.

Some male athletes such as the World Champion, Anton Kushnir from Belarus can attain heights of 50 feet or 5 stories during a trick. In comparison the highest jump height in a half pipe was achieved in 2010 by Peter Olenick at 24 feet 11 inches.

Below we have some video of Anton Kushnir, favored to win the gold medal for Free Style Skiing Aerials in the Vancouver Olympics 2010.



Here Anton is performing a near flawless trick with 3 back flips and 4 twists.

Analyze the video closely and you will see that Anton completes his first twist in his first flip on his way up. He then completes 2 twists in his second flip and the last of his 4 twists in the third flip.

The slow motion video also allows us to analyze and understand how Anton maintains good form and is able to land so smoothly out of the trick.

After each flip notice how he ends with his body in an upright position and how he slows down his twist. He even opens out his arms to help him slow down his twist.
He does this so that he can review his position and height in the air before moving into the next part of his trick.

Being aware of your body and spatial positioning in a big complicated trick like the one performed above is essential. If Anton began to twist off axis or drift laterally (to the side) during the trick, he would find it much more difficult to complete.

By "spotting" his position between each flip he is able to make any small corrections prior to the next flip, or in an extreme case to abort the trick and try to land safely.

We also see in the slow motion replay how Anton uses his arms and head during the second flip with the 2 twists to speed up his twisting motion. In the first and last flip he is only completing one twist and uses his arms minimally. In the second flip, by turning his head in the direction of his twist and bring his arms into his chest he is able to spin faster and complete 2 twists.

Form and landing are also critical components of the Aerial trick. We can see that Anton keeps his legs tightly together and his body straight during his flips and twists, for perfect form.

On landing he brings his arms forward and together in front of him and bends his knees into the land. When landing from 50 feet or more on snow or any hard surface your knees have to bend quite a bit to absorb the impact of landing.

Keeping his arms out in front and his head still and looking forward as he lands, he is also able to ensure he does not fall back on landing and can ski out of the trick.

So what's the biggest aerial trick we may see at the Olympics in 2010. US aerialist Jeret Peterson plans to attempt his "Hurricane", which consists of 3 flips and 5 twists (one more twist than in the video above). We also may see some other big tricks from Anton and other contenders.

Please contact us if you have any questions or are interested in analyzing your performance. Video Analysis is not only for the pros. It is great for any sport in which mechanics, form and technique are important. This covers just about all sports, except Poker :).

High Speed Sports Video on TV

We all already have or want that high definition plasma, LCD or even better, LED television. If you have watched sports on high definition TV, you know the difference immediately. The players are recognizable. No more asking who made that tackle or scored that goal?

Now a number of TV sports programs also show high speed replays, with the most prominent example being CBS Sports Swing Vision, which is used for CBS Golf coverage as well as Tennis and numerous other sports. We also see high speed video being used on TV and in sports to help make critical refereeing or umpiring decisions, such as the Hawk-Eye system for Tennis line calling and for the LBW decision in Cricket and high speed video replays for NFL challenge decisions.

Obviously there is a difference between high definition (or high resolution) and high speed video.
Normal TV images have up to 576 vertical lines of pixel data and the video is recorded at either 24 or 30 frames per second, depending on whether you are in Europe and Africa or in the Americas and Asia. The 576 lines describes the resolution or standard definition, while the 30 frames per second describes the speed of playback. Now your high definition television may have a resolution of 1080 progressive (1920x1080 or 2.07 MPixels) but the TV program you are watching is often recorded at the same frame rate as your standard definition TV, 24 or 30 frames per second. These days as more people have high definition TV's that can play back the higher frame rates, there are more sports broadcasts being filmed at 60 frames per second or even a little higher. This however is still not high speed video.

Therefore you can see that high definition television does not necessarily mean that we can always see slow motion replays of high speed motion. Special high speed cameras are needed to record broadcast quality high speed images such as those seen with swing vision.

High speed slow motion replays require cameras that record video data at 500, 1000 or 2000 frames per second and sometimes even higher. At the same time, they need to record with resolutions as high as 1080p, to retain their broadcast quality.

Swing Vision claims to record high speed footage with frame rates up to 40,000 frames per second. It is certainly possible for high speed cameras these days to record video at 1920x1080 pixel resolution at speeds of 2000 frames per second. To get higher speeds of capture broadcasters can trade in some of the resolution and for example record at 1280x720 pixel resolution (still HD) at 10,000 frames per second.

Below are 2 examples showing a HD video of surfing recorded at normal frame rate and played back in slow motion and a HD video of surfing recorded with a high frame rate and played back in slow motion.





If you pause the first video at any stage you will notice that the image goes a little out of focus. So although this video was filmed in HD, it was not filmed with a high frame rate. The fast motion of the surfer causes the paused video image to blur a little as her frequency of movement is faster than the frame rate of the camera.

The second video was recorded with the Typhoon HD4 high speed camera which can record video at 1280X1024 pixel resolution (1024 HD) at 1000 frames per second for full resolution. If you pause this video you will notice the clarity of the image. The surfer and wave frequency of movement is slower the camera frame rate.

We can see the difference between HD video of sport recorded at normal speed and high speed. The high speed recording allows for much more clarity in viewing high speed movement and therefore the chance to analyze performance in much more detail. In these surfing videos, you are probably thinking that the higher speed camera was not necessary to analyze the surfers movement as the clarity of the first video was more than enough. This is true but for higher speed movement such as the club during a golf swing, the higher frame rate can help identify those small improvements that can make a difference.

When capturing video of your own performance you may not be able to afford or for that matter need a high definition, high speed camera. Human movement, even fast human movement is predicted to have a maximum frequency of around 250 hertz. This suggests that even for the fastest human movement (not including equipment such as the golf club or tenis racket, which will move faster) 250 frames per second capture speed will be enough. But, the higher the frame rate you can get on your camera the more detail you will have to analyze in your video. There are numerous HD video cameras available and many of them can record at 60 frames per second and some even higher. To analyze your performance this is a great place to start.

The Skateboard Ollie

Skateboarding has taken off as a sport over the last decade and the tricks being performed are often incredible. To perfect these tricks skateboarders spend hours practicing and falling over and over again.

Video analysis is the perfect tool to learn how to do skateboard tricks. If you are learning a trick that someone else has already perfected you have the advantage of watching them do the trick and learning from them. You can also get video of yourself performing the trick and compare your technique to theirs.

Another benefit is that it is easy to setup a camera to get the best view for analyzing the video. Because most tricks are done over a defined area and in a specific direction, you can easily setup a camera to get the best field of view and angle to analyze the trick.

One of the more basic skateboarding tricks is the "Ollie" (jump). The Ollie is the basis for most aerial tricks in skateboarding and therefore it is important to learn how to do a great one.

Here is a really good video with a lesson on how to do an ollie. The video of the ollie itself is excellent because the camera is setup well and looking directly at the skateboard and movement and not at an angle.


The video gives a comprehensive description of how its done. We can get some other tips from analyzing the video more closely.

1. At the beginning of the ollie, the rider applies pressure to the tail of board. He does this to force the front of the board up into the air to start the movement. However if he only applied pressure to the tail he would simply fall off the back of the board. Watch how he also maintains his weight over his front foot so that the front of the board will only move up as he lifts and shifts his front foot.
2. Coming to the take off, the rider jumps up into the air but notice that he does not use his arms to jump. The idea with an ollie is to stay connected or at least close to your skateboard throughout the trick. If you use your arms to jump, you may jump too high above your board and end up having a long way to fall back onto your skateboard.
3. The rider in the video also lets us know that to make your ollie higher you "suck your knees up to your chest after you have jumped". This helps you to raise your center of mass and of course the height of your feet and therefore allows the board to lift higher into the air. Your center of mass is the center of all the limbs of your body, and is usually somewhere around your navel. You can move your center of mass by moving limbs. Therefore if you raise your arms you raise your center of mass. If you jump and lift your knees up higher you will also raise your center of mass.
4. Your center of mass is also important for maintaining your balance when landing the ollie. In the video note how the skaters right arm ends up behind him on the landing while his left arm is in front. He is balancing his center of mass over the center of the skateboard by opposite and equal balance of his arms. This does not mean that you need to have your right arm back and left arm forward when landing your ollie, but you should be aware that you need to balance your weight over the center of the skateboard (both forward and back as well as left and right) so that you do not fall off on landing.

Good luck with learning to do an ollie. You can try practicing your ollie first on grass or softer ground before moving to the cement. Remember to also wear a helmet, all the pros do.