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.

Replay Technology Will NOT make 100% Correct Calls

More blown calls in a major sporting event. This time in the 2nd game of the Major League Baseball World Series, between the New York Yankees and the Philadelphia Phillies. Chase Utley of the Phillies was called out at first base, when video evidence suggested he had touched the base before the ball hit Mark Teixeira’s glove. In the same game Ryan Howard was judged to have caught out Johnny Damon, when the ball looked to bounce before hitting his glove. There have been a number of poor calls in this seasons MLB playoffs once again, and blown calls are happening in numerous other sports, including soccer and tennis.

The technology of high definition and high speed video of today can easily eliminate many of these blown calls. Sure there is the argument that using video replay can slow down the game. In baseball in particular this would be truly frustrating, but we would I think all prefer to see the right call made most of the time, particularly in big games such as the World Series.

Cricket is a great example of where camera technology is used to good effect. The cameras are setup side on to the crease (batters line) and can see both the wickets and the crease. In most cases just this one camera would be enough to determine the position of the batter as well as whether the wickets bails had been dislodged. If the umpire on the field is unsure of a run out situation, he will refer the decision to the camera technology, or the 3rd umpire, who will make a definitive decision after reviewing the video footage.

Although we definitely support the use of video analysis to assist umpires and referees, it is important that everyone; umpires, athletes and fans understand that even with video analysis a call can not be 100% correct every time.
Video footage cannot always capture the event from the correct angle or the video cannot be slowed down sufficiently to determine some calls. The fact is that the video footage may not show enough evidence to support or over rule a call.

Fans in particular make the mistake of believing that video evidence will always be able to determine whether a call is correct. Unfortunately this is not the case.
If the camera reviewing a line call or judgement does not have a direct view, then the video image may not help to determine the accuracy of the umpire's call. When close calls are viewed from an angle given by a television camera, they can sometimes give misleading evidence of the accuracy of the call. This can be particularly problematic for example, when using one camera angle to determine whether a base runner has been thrown out. The base runner is running between the bases and the camera could be setup at a good angle to view when the runner touches the base. However, and here is the problem, the ball may be thrown in to the fielder from anywhere on the field (this cannot be determined in advance), therefore the camera setup to view the runner may not be in the best position to accurately determine when the fielder caught the ball and it will be possible for incorrect judgements to be made. If on the other hand we have a great view of the fielders glove and ball, we may have the incorrect perspective of the base runner and when he touches the base.

Of course these 2 situations did not take place in the 2nd game of the MLB World Series, but they also cannot be discounted.

Take a look at the 2 photographs below.


In the above pic we have the view from one camera and shoe looks like it is on the edge of the mat.
Now lets take a look from a second camera with a better view of the edge of the mat and the shoe.

Of course it is pretty obvious from this camera angle that the shoe is just short of touching the mat.
From this we can see that the incorrect camera angle could result in an incorrect call.

The problem of incorrect camera angle could be solved by having multiple cameras, all synchronized with a time source and calibrated so that the 3D position of the ball can be determined. This is how the Hawk-Eye system for Cricket and the Tennis challenge system works. Beside the fact that this type of technology requires numerous cameras, can be very expensive and requires processing time before a decision can be made, it too can suffer from inaccuracies when the ball or target being tracked is hidden from the view of a number of cameras. This can often be the case when their are numerous players on the field, or the lighting is not ideal.

So we know that video analysis of umpiring and refereeing decisions are not 100% accurate. In fact the Hawk-Eye system claims they have an accuracy of 3.6mm. This means that the ball can miss the line by 3.6mm in Tennis and still be called in by the system. In NFL football when a call is challenged and a review takes place, often the result suggests that there is insufficient evidence and the call on the field cannot be over ruled. This insufficient evidence occurs because the camera cannot get the best view of the ball and its position because of the scrum of players or a camera angle that is not optimal.

The umpire or referee has a distinct disadvantage to technology. He or she only gets one chance to get it right. If they fail to get into the best position, have the best view of the play, find the best perspective to catch all the action and happen to blink at the critical point, they could easily make the wrong call.
The camera even with the possible errors in perspective or lighting and the small errors with 3D tracking , can capture high resolution and high speed footage and replay it over and over again.
This advantage will ensure that technology will get the call right more often than even the best and luckiest umpires and referees and should be used whenever an umpire is unsure of the call to be made.

A final thought. While we wait for technology to be used, we should remember that even video footage could result in incorrect decisions. There will always be some statistical error, only a lessor error than those made by human umpires. Fortunately with technology, line calls can not be biased by emotion but only based on whatever video footage is available. With this technology even the teams we support will catch a few breaks in the long run.

Video Analysis of the Basketball Free Throw

We know why you visit our blog, to learn how to capture and analyze sports performance. Today we present our first videos and some biomechanical analysis done with free video analysis software.

Before we begin, we want to remind you that our intention is to show you the tools you can use for the video analysis of sports. We are biomedical engineers who have done research and work in sports performance analysis, but no one can be an expert on all sports. Therefore, although our biomechanical analysis is correct, our coaching tips (which we will minimize) should be evaluated with a professional coach in the appropriate sport, and must be evaluated on an athlete-by-athlete basis.

With the NCAA basketball tournaments about to begin and the regular season of the NBA about to end, we know many of you are spending a lot of time either watching or playing basketball. In honor of March Madness, our videos this week are of a basketball free throw. We have video of two subjects with very different techniques shooting a free throw. We have set up our camera on the side of the subject, as we wanted to evaluate the subjects ball release angle.
The two videos can be seen below. Notice that both the free throw shooters are right-handed therefore it would have been more appropriate for us to shoot the video from the other side of the court, so that we would have a clear view of the right arm. However, in this case, lighting conditions and other background interference meant that shooting from the left side of the athlete would result in a sharper image to analyse. We were, however, lucky that in both videos we can see enough of the shooting arm and ball to evaluate the release angle that we are interested in.





With these two independent videos there is already so much we can analyze. We can see that Subject 1 jumps quite high off the ground for his free throw and also falls forward, while Subject 2 goes up on his toes. As the camera was set up in almost the same position, we can immediately notice that Subject 2 is quite a bit taller than Subject 1 and we can take that into account in our assessment. Subject 1 is jumping in order to gain more height on his free throw. This is causing the ball to come out of his hand at a flatter angle.

A feature of many free video analysis software is that we can compare two subjects side by side. When comparing 2 subjects, it is important to also synchronize the video to a specific event. In our comparison video below, we have synchronized the two subjects' free throws at the point of ball release. We need to synchronize video for comparison because not all videos are the same length, as some subjects may take longer to shoot their free throw than others. If we tried to analyze two videos of free throws that were not synchronized, we would have a very difficult time ensuring that we could see both subjects releasing the ball at the same time. The free video analysis software we used allows us to synchronize side by side video, but not to save it out as an avi. We therefore used a well-known video analysis software to create the synchronized view you see below:



If you are a basketball coach, you can probably see a few things that can be improved for both

Subject 1 and Subject 2. Please send us your comments or coaching tips if you have suggestions.
We however are going to suggest some improvements for subject 1 based on a little bit more video analysis we did with a free video analysis software package.





Here are two freeze frame images of Subject 1 (top) and Subject 2. Using free video analysis software, we have calculated the angle of release for both subjects, and zoomed in on their arms and the ball at this release point. Subject 1 released the ball at 48 degrees to horizontal while Subject 2 released the ball at 79 degrees to the horizontal.

Now for some basic physics. The diameter of the basketball rim should be exactly twice the diameter of the basketball. In other words, two basketballs can fit through the hoop at the same time (if everything is perfect and there is no net). During a free throw or any basketball shot from the outer court, we are throwing the ball on an arc. The ball needs to move forward as well as up (for most of us) to get it into the net. The ball can either move on a flatter arc (Subject 1) or on a steeper arc (Subject 2). On a flatter arc the ball will not go as high but will move forward further and quicker; on a steeper arc, the ball will go higher and not as far. This means a free throw on a steeper arc will come down straighter and take advantage of the size of the basketball rim, while a flatter free throw will need to be far more accurate as a ball moving forward is more likely to hit the rim.

Subject 1 should try to put his free throw on a higher arc to take advantage of the physics described above. He can see immediately from this video analysis that his free throw is at a 30 degree flatter angle at release than Subject 2 and while practicing his free throws, should concentrate on releasing the ball on a higher angle. Once Subject 1 has some time to practice, we will get another video of him and see how he has improved.

Hope you enjoyed this first full Video Analysis. Remember that you too can do this type of in-depth analysis. All you need is a video camera and a little understanding. Follow us to get more tips, tricks, and understanding in using your video camera to analyze different sports.

We are happy to answer any questions or hear from you, please leave us a comment.