Can Kobe Shoot Without Using his Index Finger?

The 2010 NBA playoffs are about to begin and the defending champion Lakers look to be a couple of players short of a repeat. The main problem for the Lakers is Kobe Bryant and his dip in shooting form. His shooting has always been his most dangerous weapon and it is not firing now.

Over the last 5 games Kobe has attempted 109 field goals and made only 43 of them averaging just over 39% when his season average is around 45.6%. Kobe suffered, along with other injuries, an avulsion fracture to his right index finger earlier this season. In most games he has managed to continue to shoot reasonably well with this broken finger as can be seen by his season average field goal percentage, but something has changed recently.

Can we blame his finger for his loss in shooting form? Unfortunately we were unable to obtain any video of Kobe that focused on the hand and how he may have changed his grip or the mechanics of his shooting to account for the pain or the cast/bandage on his finger.

But lets take a look at this slow motion video of a basketball free throw and particularly of the hand and fingers at the point of release.



Here is a close up of the hand at point of release. Notice that this recreational player shoots the ball off the fingers of his shooting hand as he should. Our player does not follow through with his wrist correctly, but our focus is on his fingers. We can see that the ball comes off his fingers and that the index finger imparts the last bit of spin and push to the ball. This is expected as the index finger can execute tasks with more control than any of your other fingers, just think which finger you use on your iPhone or iPad to navigate around.

Back to Kobe. It is pretty obvious from the video that the index finger plays an important role in shooting the basketball. But Kobe has had this injury for a while and although it dented his shooting average for a few games in January, it seems to have only recently started affecting him again.

In order to continue to shoot well after the injury in December 2009, Kobe most likely studied his shot on video and made adjustments to the way he executed the final phase of the shot (the ball release). With a cast on the index finger he made and adjustment to keep this finger off the ball and out of the way when shooting and used his middle and ring finger to create the backspin and final push for the shot. He definitely seemed to work it out but he never looked exceptionally fluid with his shooting technique, even when he made the shots.

In the last 5 games something has changed. It is possible that Kobe's finger has healed sufficiently and he is no longer using a splint. The basic wrapping may allow him to use the index finger during shooting once again. The problem may be that the finger is not entirely healed, otherwise it would probably be out of the wrapping altogether. Kobe may be trying to go back to his normal shooting mechanics or simply trying to once again tweak his mechanics to accommodate the new condition of playing with his index finger taped. Either way he will need to find some mechanics that will make him an effective  shooter through the play offs as the Lakers will most likely need him to succeed again.

The use of video analysis can assist any athlete in making the necessary adjustments to improve or change mechanics when needed. Of course we do not suggest that you continue to play and change your mechanics if you are injured. Unless you are payed to play, it is better to analyze video and practice to perform correct mechanics that will improve your game and also prevent injury.

Analyzing Usain Bolt's 19.19 Second 200m World Record

The Scientific Research Project at the 2009 IAAF World Athletics Championships has released the data for the 200m final and now we can break down Usain Bolts incredible 200m World Record of 19.19 seconds.

Click on the table below to get a closer look.

Let's pick out the key points for this race and see if we can compare them to his 100m splits.

1. Bolt's reaction time in this race is 0.133 seconds. This is much better than his 0.145 second 100m world record reaction time. However we have already discussed this in a previous post and know that Bolt can start fast too.
2. As expected Bolt runs the second 100m (from 100-200m ) faster than the first 100m. This is expected, as the start and getting up to speed takes time, while the second 100 meters can be run at close to maximum speed. Bolt's first 100m was run in 9.92 secs with the second hundred taking only 9.27 secs (a negative split). Interestingly, Michael Johnson ran the second 100 meters of his then World Record breaking 19.32 sec 200m race in 9.20 secs, which is faster than Bolt's second 100m in this race.
3. Bolt's maximum velocity during the 200 meter race occurs somewhere between the 50 and 100 meter mark. His average velocity over this 50m part of the race is 11.57 m/s (25.88 mph). In comparison his 100m maximum velocity was 12.27 m/s (27.45 mph). Once again this is to be expected, as the 200m athletes needs to have reserves to complete the race and cannot run at the same speed as in the 100m race.
4. Bolt slows down over each of the last two 50 meter splits as he begins to fatigue, covering each of the following 50 meter splits 2 tenths of a second slower. Watching the race, we can see that he is really straining to run fast, but he is still slowing down. It is expected that any athlete will slow down over the last 100 meters as the muscles tire, two hundered meters is a long way to go at full speed. We have mentioned that in this World Championships Bolt had already run four 100m races and three 200m heats before lining up for the 200m final. This has us excited at the prospect of seeing Bolt break this 19.19 second World Record, when he is fresh and has not run seven previous races.

All that is left to say is that we can expect Bolt to go faster in the 200 meter and 100 meter races in optimal conditions.

There is one record he does not hold yet and that is of the fastest 100m relay split. This record is held by his Jamaican team mate Asafa Powell in 8.70 secs. The anchor leg relay split is much faster than any of the other sprint splits, because the athletes have a flying start and are therefore able to reach top speed much sooner in the 100 meter distance. If Bolt anchors the 4X100m relay in Berlin this week, we expect that relay split record to be broken.

Improving your Basketball Free Throw with Video

The NBA playoffs are now in full swing. King Lebron James is showing us all why he deserves the MVP and why the Cleveland Cavaliers must be considered the favorites for the title. Free throw shooting in the playoffs is even more critical than during the regular season and therefore we bring you a second installment of our video analysis of the basketball free throw.

In March we introduced the Video Analysis of the Basketball Freethrow and compared two different subjects and their respective shooting techniques. We focused on the angle of release in particular. This week, we captured video of our Subject 1 from March, to see if he was able to use the video analysis to make improvements. Once again we will use video analysis software to determine and quantify whether any significant improvements have been made with his technique.

As you may recall from our first analysis, it was noted that this subject could improve his chances of making a successful free throw by increasing the angle of release of the ball, so it falls on more of a downward arc as it gets closer to the hoop. Let's take a look at some stillshots that were created with some analysis software.





This week we filmed our video at a different court and set up our camera on the right side of the subject so we could see his right arm more clearly. Unfortunately in the earlier video (top photo), we needed to set up on the left side of the subject for lighting reasons. In order to compare the subjects free throw technique, we used our analysis software to create a mirror image of the subject from the March video (top photo). This allows us to watch the video and study the still shots with more clarity. When we mirror the image, it looks as if the subject in the mirror image is left handed, but of course this is not the case. The mirror image function of video analysis software is very useful for comparing left and right handed players or comparing video of movement in different directions, as we do here.

Ok, let's get onto the analysis. For the "before" shot (subject with blue shirt, top photo), we see the angle of release is 48 degrees from horizontal. For the "after" shot (subject with red shirt, bottom photo), the angle of release is 61 degrees from horizontal. This is approximately a 27% increase in the angle of release from the first to second shot. As we mentioned in the March post the higher the angle the higher the arc of the free throw. Therefore, we can safely say the ball will be coming down in more of a downward arc as it approaches the rim. If the subject continues to shoot with the technique seen in the more recent shot; this will likely result in more free throws made.

The video below shows a side by side view of the subject's free throw attempts in full motion.




Besides the improvement in release angle we can also note how the subject follows through on each shot. Although it would be easier to see from a behind or front-on view, we can still see that the "before" subject follows through across his body, whereas the "after" subject follows through more towards the hoop. Following through towards the hoop is going to help the subject's chances of shooting the ball towards the middle of the hoop, rather than to one side or another. For obvious reasons a ball moving straight toward the hoop is more likely to go in to the basket.

Following through towards the hoop on a free throw (or jump shot) helps ensure the player moves the ball towards the target throughout the shot, rather than having to rely on perfect timing to get the ball going towards the hoop. Minimizing this error of the shot going left or right makes it easier for the subject to now focus most of his attention on the angle of release relative to horizontal.

Remember to use your video camera, so that you can see and analyze your own free throws. Once you see your shot you will have a better understanding of how to improve it. We hope this posting helps you get the most out of your free throw practice sessions. Whether you need to make free throws to get into a pickup game at a park, or your team's relying on you to hit the game winning foul shot, the ability to make free throws consistently is an important skill for every basketball player to have.

Andy Murray's Tennis Serve

Last week, Rafael Nadal won the 2009 BNP Paribas Tennis Tournament at Indian Wells, California, defeating Andy Murray easily in the final.

As we watched the tournament, we heard frequent discussions of Murray's second serve, and that if he could develop a better second serve he would be almost unstoppable. Of course, he was almost unstoppable at Indian Wells, but did lose badly in the final, mostly because of poor serving. In that final match against Nadal, he lost his service games four times and won only 6 of 16 (38%) of his 2nd serve points. Let's take nothing away from Nadal though; he has the best return game in tennis, possibly the best ever.

All tennis players, including beginners, know the importance of the serve. A good serve can result in easy points and puts pressure on an opponent. The first and second serves in tennis usually have different goals. With your first serve, you want to win the point with an ace, service winner, or at least put your opponent in a defensive position for the next shot. The first serve is generally flat and fast, and you can take more risk, knowing you have an attempt at a 2nd serve if you need it. The second serve is your backup safety. Your priority is to get the second serve in and start the point. If you miss the second serve, you will double fault and give your opponent a free point. Most tennis players put a lot more spin on the second serve, but this tends to reduce the speed of the serve.

Because of the slower pace, the second serve often gives the receiver plenty of time to get into position to hit an aggressive return. However, if you can make your second serve look similar to your first serve, at least in terms of the service motion, you can make it difficult for the receiver to predict the speed (and type of spin) of the serve, and you may retain a significant advantage, even as you serve slower and with more control.


We found some video of Andy Murray's first serve and decided to look at it from a biomechanics point of view. This video is set up very well for video analysis. The camera is set up along the baseline, which allows us to get a side-on view of Andy during his serve. We can also see the complete service motion in the video, including the racquet head, and can see the racquet make contact with the ball. It would have been great if we could've seen the complete ball toss (the ball goes out of the top of the screen) and if the camera had been stable and mounted on a tripod; but in general, this is good video sports analysis footage.



The power in the tennis serve, like many throwing or hitting sports (baseball hitting and pitching, football throw, and golf) is created by a chain of events. Each part of the body loads up with energy and transfers its energy to the next link in the chain. The timing of this energy transfer is critical to creating racquet head speed and therefore a good, fast serve.

In Andy's serve, we see how he starts with his knee bend as he throws the ball up. You may also notice that as he bends his knees his hips turn away from the court. He then transfers this energy now stored in his hips by bringing his back foot up to his front foot and rotating his hips into the court. Once again notice that as he rotates his hips back into the court, his shoulders now rotate away. This counter rotation in both hips and then shoulders creates the potential for racket head speed; Andy is coiled up and ready to explode his racket toward the ball.

As he does this, he releases the potential energy, rotates his shoulders back into the court, and throws his racket at the ball. All these energy transfers add up to create the speed with which he will hit his serve. If his timing is off, his speed will not be as high.

The ball toss is, of course, just as important. If you do not throw the ball consistently, it will be very diffcult to perfect the timing of your kinetic chain (described above). Andy's ball toss is high and a falls about a foot inside the court. If you want to hit a good hard serve, the ball needs to be in front of you, so that your body and racquet are moving forward when the ball is struck. If the ball toss is directly above your head, it is much more difficult to get theball moving forward with as much pace.

Ok, so Andy has a great first serve, and we can see that here. It is his second serve that the commentators were discussing. Unfortunately, we were unable to find any good footage of his second serve to compare it to his first serve. We are sure his coach is working hard on improving his kinetic chain sequence and timing to make it more difficult for his opponents to read his second serve.

Please post comments and let us know what you think, or whether you have any questions or suggestions. We would be delighted to hear from you.

Sports Analysis: The Camera Specs

In the last blog Video Analysis of Sports 101 we said that we would discuss what makes a good camera for video sports analysis, so here it is.

If you already have a digital video camera there is no need to go out a buy a new one simply based on our recommendations here. If you follow the setup rules we discussed in Video Analysis of Sports 101 you will be able to obtain great footage that you can analyze.
However, if it's time for you to pick up a new DV camera, then getting the right camera can really help you obtain excellent sports analysis footage and make your video analysis clearer.

Speed and Size
Like most sports, a good sports analysis camera needs speed and size. There are a few different speed and size measures of a camera and they are discussed below.

Frame Speed
Most off the shelf DV cameras have a standard frame speed of 30 frames per second or fps(NTSC) in the North America and 25 fps (PAL) in most of the rest of world. What this means is that the camera records 30 pictures every second, one picture every 0.03333 seconds. 30 frames per second is the speed at which most regular television is recorded and viewed. When these 30 frames are played back at full speed every second, our brain is unable to distinguish between the individual pictures and we see a flowing video.
However, if we want to analyze a tennis serve then we need to slow down our video and look at each one of these 30 frames of every second and this is where a problem may arise. As the serve is generally a quick motion, we will probably find that if we only record 30 fps then the arm will look like a blur during the serve motion and we will be unable to analyze it properly. To solve this problem we can record the motion at a higher frame rate, say 60 fps and get double the amount of pictures every second. This will give us more data to analyze and reduce the possibility that the motion will be blurred.
In general the more frames we can capture per second the better our analysis can be. Luckily though there is a limit. In most sports when analyzing the human body movement 250 fps is sufficient. If we then want to include say the golf club or tennis racket and analyze its movement, we once again need higher speeds maybe up to 500 fps.

Many sports TV programs now use high speed cameras to analyze sports. Here is some recorded high fps video. A lower fps camera would often show blurring as we watched each frame like this.


Unfortunately though there are very few off the shelf commercial cameras that can record high frame rates. You can find some cameras that can record 60 fps, but if you want to go higher, costs can increase substantially. We think a 60fps camera is a perfect start for doing your own analysis.

Shutter Speed
We can get away with the usual 30 fps as long as we have a high shutter speed. Shutter speed determines exposure time, or how long the cameras sensor is open to receive light and therefore record the frame. In sports analysis the higher the shutter speed the less blurred our image will be. However there is a trade off - a faster shutter speed will allow less light onto the cameras sensor and therefore if we use a high shutter speed we need to make sure that we have sufficient lighting as we discussed in the last blog. When looking at a camera for sports analysis, look at the shutter speed and whether it is manually adjustable. A camera that automatically adjusts its shutter speed to the lighting conditions can make you forget the importance of ensuring good lighting on your subject.

Resolution
We all know about resolution from high def televisions. High def television can only display those high definition images if they were recorded by a high definition video camera. The resolution of a video camera is a measure of how many pixels our camera sensor has. Luckily for us most video camera manufacturers are now making HD cameras with about 1920x1080 pixels or 2.3 Mega pixels. Of course a higher resolution is always better just like it is on our TVs.



Lens Choice
There are 2 important aspects of a lens for sports performance capture, aperture (f-stop) and focal length and optical zoom.

Aperture

The aperture or f-stop is a measure of the amount of light the lens of the camera will allow through. A lower number will allow more light into the camera and a higher number less light. Most DV cameras have f-stops as low as 2.5 which is good enough for sports analysis purposes. Once again just like with shutter speed there is a trade off. A lower f-stop can often result in a lower resolution image. This does not mean that the cameras sensor has less resolution but that there is a trade off with lighting and quality. Once again this points to making sure you have a good light source for your recordings. With a good light source you can use a lower f-stop and therefore obtain a better resolution image.

Focal Length
The focal length is the distance from the lens to the camera's sensor. A smaller focal length means that the camera will capture a wider angle of view and see more in the frame, while a large focal length allows the camera to see more details further away. Focal length and optical zoom therefore are linked. Optical zoom of course allows us to zoom in or away from an athlete.

Most DV cameras come equipped with optical zoom and will read something like 49-735mm, which is the range of focal lengths that can be achieved with this camera.

The more optical zoom we have the further away we can be while still recording excellent footage for analysis. Now its up to us to use that optical zoom effectively by positioning our athlete correctly in the field of view. Check out Video Analysis of Sports 101 for details.

Also don't get tricked by digital zoom. Digital zoom is not our friend and if used can reduce our actual sensor resolution considerably. It is far better to reposition our camera closer to the athlete than make use of digital zoom.


We hope these tips help if you are looking to choose a new DV camera for sports analysis. Remember though, any camera can work; but if you want more detail you need to ensure that you recorded the detail with your camera. You cannot analyze details you do not have.

We welcome any comments or suggestions on our blog. Have a great week.

Dudley Tabakin

Video Analysis of Sports 101

Welcome to the Video Analysis of Sports blog. As this is our first article, we will take this opportunity to introduce ourselves.

We (Dennis and Dudley) have a combined 20 years experience in motion capture and biomechanics with a special interest in sports performance and injury prevention. Through our consulting company Sadaka, LLC http://www.sadakallc.com ,we offer services to sports professionals, sports equipment manufacturers, hospitals and motion analysis software and hardware companies. Some of our past clients include Titleist, FootJoy, Warrior Hockey, National Pitching Association, NASA, Shriners Childrens Hospital and Vicon Motion Systems.

Video analysis of sports performance is often the domain of professional athletes and large companies or research institutions. This analysis is done with expensive 3D video camera equipment and complicated software to ensure high speeds and accuracy. However there are some basic techniques that can be used by any individual to evaluate their own performance and get great results using a simple digital video camera and a little understanding of biomechanics. The video camera will require a small cost (we will discuss what makes a good camera in a future posting), but we will supply you with much of the biomechanics understanding for free on this blog.

Reviewing video clips can be a great way to provide coaching feedback to players, as well as a means to emulate one's favorite athletes. Whether you're a professional all-star, high school athlete, or weekend warrior, seeing yourself from a different perspective can help improve your performance and/or minimize your chances of injury.

So in this first posting, we'll start right at the beginning and describe what features make a sports clip suitable for video analysis of an individual, and what you can do to ensure the clips you film will meet those requirements. Future postings will demonstrate the various levels of analysis that can be performed on suitable videos, using a range of available software, from basic free software to detailed 3D analysis.

What makes a good sports clip?
A good sports clip of an individual shows the athlete's full range of motion (ROM) during an action, with the camera positioned such that angles can be accurately calculated (this will be discussed in more detail later). Filming the athlete's ROM can be accomplished by simply zooming out or moving the camera backwards until all the desired features are in the viewer. In general, it's recommended to have the camera as close to the athlete as possible and still capture the entire ROM, as this will make the most use of the camera sensor's resolution. For example, if we were to capture a basketball player dunking the ball we would want to ensure that our camera can see the complete action from take off until the player puts the ball in the net. Our camera would therefore need to see the ground at the take off point as well as some space above the rim of the the net.

Another important factor in obtaining a great sports clip is to make sure that your camera is stationary. There are some motion capture software available that can handle a moving camera, but for now we suggest that the camera is mounted on a tripod and is not moved while the video clip is being filmed. This means that you should ensure the full ROM (described above) can be captured in this one shot.

How you can film useful footage:
Camera placement
In general, most sports clips we watch on tv are best suited for analyzing strategy and teamwork because they provide an overall picture of many or all of the competitors and the playing field. However, when it comes to analyzing an individual's performance or technique, it's not only important to focus the camera on the single athlete, but the angle we film from must also be taken into account. It's best to use "orthogonal angles", meaning the camera is directly in front of, behind, or to the side of the athlete. Golf coverage usually does a nice job of this, providing shots of the golfer either "face-on" or "down-the-line". Here's a great face-on view of Tiger Woods' swing:



And here is a down-the-line shot of his swing:



Notice these cameras are level with the golfer; they're not filmed at an upward or downward angle, meaning it's possible to accurately calculate some angles, if that's what is desired from the analysis.

Background/contrast
Although the above clip is a beautiful view of Tiger's swing, the footage could have been improved by having him wear clothes that were a different color from the background. Black clothing with a black background can make it difficult to accurately evaluate the amount of hip and shoulder rotation - two commonly analyzed characteristics of a golf swing. Not that having a solid black background is a bad thing though; on the contrary, if you can manage to film your athlete with a solid-colored background, you are well on your way to filming some nice footage for analysis.

Lighting
As is true with taking most photos, it's ideal to position the camera and athlete such that the light source (e.g., the sun) is behind the camera and illuminates the athlete. This will provide a crisp view of the athlete, and will allow you to use a more open setting on the camera's aperture.

Now that you're up to speed on the basics of filming great video for analysis, grab your video camera and start practicing! Follow our regular blog postings, and see how you can create your own analyses of your videos, using a variety of software packages.

-Dennis Ho