Measuring Michael Jordan's 1987 Slam Dunk Contest Vertical Leap

Comparing the vertical leap of past winners of the slam dunk contest would give us great insight into who really has the best dunk. So time for a Video Analysis of Sports Vertical Leap Dunk Off.

Last week we discussed how we could use broadcast footage of the slam dunk contests to measure the vertical leap of each player during the dunk. We looked at Vince Carter's 2000 Slam Dunk Contest win and estimated that his vertical leap was about 37.6 inches. see Measuring Vertical Leap at a NBA Slam Dunk Contest

The above story was picked up by Patrick at givemetherock.com, who said "I would love to see how other dunks measure up".

The original plan for last weeks article was to use video of Michael Jordan's dunk from the free throw line in his 1987 Slam Dunk contest win. However Carter's dunk from 2000 gave us a better example. To measure the vertical leap from broadcast footage of the slam dunk contest we needed one view and image from the video that contained 4 elements. 1. A full view of the player, 2. a view of the underside of the backboard, 3. the basketball rim and 4. the floor below the backboard. All 4 of these features need to be in the image.

GiveMeTheRock.com want to see how other dunks measure up so I went back to YouTube to try and find better footage of Jordan in 1987.

Although the dunk from the free throw line is iconic, it may not be the dunk in which Jordan obtained his maximum vertical leap, because for this dunk he needed to cover the distance from the free throw line to the basket and therefore height was less important. During the same slam dunk contest though, Jordan completes a sideways dunk which scores him a perfect score of 50.

This dunk required Jordan to get higher to complete, so lets use this one to compare his vertical leap to Vince Carter's 37.6 inch leap in 2000.

Here is the video. Jordan's sideways dunk can be seen at about 1:59 for his highest point and the dunk from the free throw line can be seen later on.



Assuming his highest point is at 1:59 in the video, we take a snap shot and then use our known measurements. This time we do not need to use the width of the backboard because we have a side on view that allows us to measure the distance from the rim to the ground:

1. Height of the rim is 120 inches above the ground.
2. Michael Jordan is listed at 6 foot 6 inches or 78 inches.
3. Hip height of a standard man is approximately 53% of his total height. Therefore Jordan's hip height is about 41.3 inches.

These measures are ideal for making a comparison between Carter's vertical leap and Jordan's. The fact that they are of the same height, 6 foot 6 inches, allows us to ignore any height advantage. As an example Nate Robinson needs to have a higher vertical leap than Dwight Howard to make a dunk, for the simple reason that he is much shorter. In our comparison both players are the same height and therefore they both require the same vertical leap to make the dunk. In a slam dunk contest it is not only about making the dunk and this is why we are interested in comparing their vertical leaps during the dunk.

Lets look at the image at 1:59 and the measures we can make.

Because it is difficult to make out the backboard we chose to use the height of the rim above the floor for our scale measure. We know this height is 10 feet or 120 inches. We draw the blue line down from the rim to the floor and give it the scale we desire 120 inches.

Now we can measure how high Jordan's hips are above the ground. This measure at 83.88 inches (yellow line). Subtract Jordan's standing hip height of 41.3 inches from this measure of his hip height at the top of the dunk and we get an amazing 42.6 inches or 6 inches (half a foot) higher than Carter's hip height in the 2000 slam dunk contest.

Of course the different angles of the cameras and footage and the differences in how the vertical leap measurements were made (not using the backboard for scaling in this image but using it for Vince Carter's dunk) means that inaccuracies will still exist. However a quick look through the literature and some past studies of Jordan at his best suggest that he could regularly jump 42 inches during a one handed dunk.

We will therefore assume our measure of Jordan's 1987 dunk to be a good estimate and based on the 2000 video footage of Carter's dunk we will assume that our measure of 37.6 inches is a good estimate of vertical leap for his dunk.

There is no doubt then that Jordan wins this video analysis of sports dunk off. Anyone think they have footage of a dunk with a vertical leap that can top Jordan's?

Measuring Vertical Leap at a NBA Slam Dunk Contest

The Slam Dunk contest at the NBA All Star event is usually spectacular. Dwight Howard flying with his Superman cape is a great highlight. Slam dunks are all about getting up high and we want to know how high they jump?

Recently a reader of this website asked whether he could measure the vertical leap of winners of past slam dunk contests from NBA footage of the event, including Michael Jordan's leap from the free throw line in 1987. Unfortunately in a basketball broadcast the camera and usually cameras are often moving, panning or zooming to catch the best view of the player, particularly during a dunk. Analyzing the vertical leap from this footage can be tricky.

The answer to the readers question depends a lot on the video footage that is analyzed, but here are a few basics of video analysis and some ideas of how the vertical leap height may be measured from the footage.

1. Camera angle and view needs to be good to make useful measures of heights (see Video Analysis 101 ). Most footage of the slam dunk contests used multiple cameras and they were often zoomed in at just the wrong time, making this difficult.
2. We only need one image of the player at the peak of his jump to measure vertical leap, but we will also require some scaling so that we can convert the pixels in the image into a real measurement of height. To do this we need to have a single image that includes the player, the bottom of the backboard, the rim and the floor directly underneath the backboard. With all these in one frame of the footage we can make a measure.
3. We will also want to know the height of the player so that we can use this height to estimate their vertical leap. We will measure the height of the jump and subtract the players standing height to get a measure of their jump.
4. Even if all the information is available to us to make the measure, it will still be an estimate as the camera angle may be slightly off and this will make our measure less accurate.

Would this method in fact work?  We can try to analyze a slam dunk contest from 2000 and Vince Carter winning with some serious air. Check out the video below:



From this video we can grab a snapshot of the action at 1:44 in the video and do some measures. First we needed to know some standard basketball measures.

1. Width of the backboard is 72 inches
2. Height of the bottom of the backboard is 114 inches above the ground
3. Vince Carter is listed at 6 foot 6 inches or 78 inches
4. Hip height of a standard man is approximately 53% of his total height. Therefore Carter's hip height is about 41.3 inches.

Now we can make some measures of Carters vertical leap height. This footage has a graphic that measures his jump height at 37 inches. We will use this as a measure to see how well we can do at measuring the jump height using our estimates and video analysis. See the image below:

In the image we can see the following measures:

1. We know that the width of the backboard is 72 inches. We have drawn a green line along the bottom margin of the backboard and used this known distance to scale all our other measures.
2. Next we used the blue line to draw a vertical from the bottom of the backboard to the ground. We know this should be 114 inches. Unfortunately as our scale comes from the width of the back board (green line) we couldn't get it to measure exactly 114 inches with our estimates, but we are close at 114.19 inches.
3. Finally we measure Vince Carter's hip height at the top of his jump and with the yellow line. Here we needed the line to go from the floor at the same height as the blue line to Carters hips. We estimate his hip height at 78.9 inches or 6.575 feet which is almost his head height.
4. We can also notice that the camera is not perfectly horizontal with the backboard. We can see that the backboard is not perfectly horizontal accross the screen, although it is close. This angle may reduce the accuracy of our other measures.

Finally we can estimate Carter's maximum vertical leap from this video footage and for this particular dunk. We know his standing hip height is estimated at 41.3 inches and we estimated his hip height at the peak of the jump for the dunk at 78.9 inches. We subtract the standing hip height from the jump height and we get 37.6 inches.

If the measure shown during the broadcast at 37 inches is accurate then our estimate is pretty good and we  can probably try to do the same measures on other broadcast footage of slam dunk contests. All we need is one image with a view of the backboard, the player and the floor below the backboard as well as knowledge of the dimensions of the basketball backboard and height of the player.

We are always interested to hear about your video analysis projects or hear your comments. We are also available to consult to all our readers on their video analysis and biomechanics needs.  

Lebron Will Pick Complementary Team Mates

Lebron James' Thursday night "Decision" ESPN special, has created crazy reactions from NBA fans and even normally disinterested bystanders alike. During the special, Lebron will announce the NBA team he has chosen to join or stay with, in his quest for an NBA Championship title.

Where will Lebron play the next 5 odd years? Reports suggest his decision is made and he will join Bosh and Wade in Miami, but we won't speculate or add to the confusion.

We know why Lebron can command such attention, he is a phenomenal athlete and basketball player. Along with Dwayne Wade and Kobe Bryant, he stands as the best of the NBA. There is little doubt that he will make any team he plays on a championship contender.

In Cleveland Lebron has contended for a number of years now, but has still not held the Larry O'Brien trophy. Whichever team he chooses, he will want team mates that complement his game by being skilled where Lebron is weak.

Lebron has very few weaknesses, but one possible weakness is his jump shot. Of course with some hard work it will improve, but if Lebron joins a team with an excellent outside shooter, he will be able to achieve quicker than if he tries to do it all himself. A dangerous skilled offensive partner will also give him more space on the floor as defenders will need to cover another great player.

So Lebron has studied the video and knows which team mates will work best for him. We expect him to join the likes of D-Wade or Derrick Rose in Chicago and benefit from their strengths.

Here is James vs Wade during the 2010 NBA season. The evidence suggests a strong partnership with every possibility of a championship.

Sharing Sports Video Analysis

On the Video Analysis of Sports site we often show you some analysis that we have done using a particular software. We have used software from Dartfish, Innovision Systems Inc. - MaxTRAQ and our favorite open source application Kinovea.

Recently we were introduced to David Keefe. David let us in on his new project called UpMyGame. You may have noticed UpMyGame as a new menu item on this website. We do not endorse one video analysis software product over another. If you read our posts regularly you will know that we believe the most important aspect of video analysis for sports is camera positioning and quality of the video footage captured. Features of a video analysis software such as drawing lines, calculating angles, scaling and measuring distance and synchronizing two videos are great to have and can be found in many applications.Therefore we like video analysis software that is easy to use, easy to share and of course as inexpensive as possible.

So why do we have a link to UpMyGame on our website? Easy to use, easy to share and free for a start, but what we really liked about UpMyGame is that it is hosted online and your videos can be analyzed, commented on and shared online by you, your coach or players or anyone you allow to view it.

The software allows you to create coaching session for players or teams and can be hosted or embedded directly into your own website. This embedding feature is one of our favorites as it allows us to do some analysis and very simply share it with you on this website.

Below is an embedded coaching session using UpMyGame. You may have seen part of this analysis before at Improving Your Basketball Free Throw with Video



The UpMyGame software allows us to measure angles, draw lines, highlight areas of interest and make comments. The audio comment tool seems particularly useful for coaches to share their views and explain their analysis in more detail.

For the athlete who is trying to get more information there is also the option to ask for coaching. UpMyGame has a simple button to "Request Coaching" which allows you to ask a coach or UpMyGame member to have a look at your video and do some analysis. The coach has the opportunity here to charge for any coaching requested or if he feels generous he may just offer to help for free.

If you are looking for some video analysis software to analyze your sports performance or that of your athletes then we suggest that you have a look at UpMyGame. The free sign up price is hard to beat and if you ask for coaching from us "Sadaka" we may make you famous as we can write about and embed (with your permission) your coaching analysis directly in one of our future posts.

Using Video Analysis for Strategy

Video analysis can be used to evaluate sports performance and technique. We discuss many of the biomechanics aspects and tools used to do performance assessments right here on this website. Video analysis however can also be used to provide detailed game strategy and analysis of on field play.

We see these game strategy statistics all the time when we watch almost any sport on TV. How many shots did Kobe Bryant take and make. What percentage of first serves did Roger Federer get in and how many resulted in winning points. These statistics are fun for the viewer, but they are essential to the coach and player in refining their strategy.

Let's take an example from basketball, as we are currently watching the NBA playoffs. Any team coming up against the Orlando Magic this year will need to find a way to get past Dwight Howard, who was once again named defensive player of the year. The teams employ a coach or video analysts to watch every play that Howard makes. Every time he blocks a shot or an opponent manages to beat him and score. Using this information they can determine how best to play against him.

Below is video of some of Howard's best blocks of last season. Notice how often Dwight is alone and far away from an opposition player as he gets into position for the block. This may seem necessary in order to make the block, or as the Orlando Magic play a zone defense he may not have a specific man defensive assignment. Coaches or video analysts though would look at this video and may be able to create plays that take advantage of his position on the floor.

Of course a team also needs to play to its strength and similar video analysis of the coaches own team can be used to determine how they may take advantage of any opposition mistakes, close any gaps or change any patterns that may be obvious and strategies the best approach to take on an upcoming game or player.

To do Video Analysis of this sort properly you need to have some basic equipment.

• You will definitely need a video camera and to set that camera up so that you can see the whole game. This can be difficult in sports with large fields such as soccer or rugby.
• For larger fields you can use 2 video cameras, with each one focused on, one half of the field.
• A great advantage in well televised sports is that much of the video footage already exists. A recorded video of an NBA game will allow you to track most of the players on the court for most of the game.
• Some video analysis software is also recommended. This software can be the same as the software that you use for performance and technique analysis, but the software must allow you to tag events. Tagging events such as the first serve will allow you to go back and look at all the first serves in one place. This will enable some statistical analysis of the results of the serve and if you have software that allows it you can also analyze each serve for technique and performance.

The website http://www.thevideoanalyst.com/ has some great information on video analysis of this type and everything that you may need.

When working with a team or player combining this type of video analysis with biomechanics and technique analysis will provide excellent resources for performance improvements wherever they are needed.

Crazy backflip dunk!

In a recent game between the Atlanta Hawks and Milwaukee Bucks, an amazing halftime feat was performed. The Bucks' mascot Bango climbed a 15-20 foot ladder (reports vary), did a backflip off the top step, and dunked a basketball, before falling onto a landing pad. Although the video was taken from a handheld camera, it's definitely something worth watching over and over again. Enjoy!

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.

Mastering the Basketball Block

Lebron James is definitely the master of the block on the basketball court. His chase downs are always spectacular and fun to watch.

There is a lot we can learn from watching Lebron's blocks particularly how he jumps keeping his head up and following the ball at all times with his eyes.

Here is some video of Lebron's top 10 blocks so far this 2010 season.

NBA's Dirtiest Players Can't Hide from the Cameras

A Sports Illustrated Poll this week announced the dirtiest players in the NBA.

Top of the list is Reggie Evans of the Raptors with 21% of the vote, far ahead of Ron Artest of the Lakers with 13% .

No argument here, Reggis Evans is definitely the dirtiest player I have watched. Ron Artest has a been a little subdued since his move to the Lakers, but he is an aggressive defender and gets in opponents faces and has played dirty in the past.

Playing aggressive defense is very different from playing dirty. There is absolutely no reason for dirty play of the likes that can be seen in the video of Reggie Evans below.

Video Analysis can be used in different ways and reviewing dirty plays is one other. Thankfully the number of TV broadcast cameras covering every inch of the basketball court ensures that no dirty play can be missed.

In European soccer, video replays of fouls and off the ball incidents can be reviewed after the game and players can be fined and/or suspended based on the video evidence.

Here is a video of Reggie Evans dirty play against Chris Kaman in the 2006 playoffs. He was not suspended for this action although he was fined.



The NBA however is not generally dirty. There are very few occasions when it would be necessary to review the video and suspend a player.

But, did Evans really expect to get away with this, when there are 3 or 4 camera angles focusing on the play. If the cameras and the notoriety of playing dirty and being seen by millions cannot prevent this type of play, then perhaps the NBA should employ a similar strategy to soccer and suspend players for dirty off the ball incidents.

Dribbling the Basketball While Running

Basketball as a sport can be made to look so easy. We watch Lebron James dribble the ball down the right side of the court while he surveys the positions of his team mates and the opposition. Suddenly he breaks left toward the basket, switching his dribble to his left hand, one more step and one more bounce then he switches back to the right hand as he elevates for the dunk.

Not once in this sequence does he look at the ball (until it is going through the hoop). As he does each movement, including side steps and head fakes, he keeps the ball bouncing slightly out in front and to the side, positioned ready for the next spectacular play.

Dribbling the ball is an essential part of basketball. A player that can dribble with confidence and control will have more options to attack the basket and get good looks to shoot a jump shot or attack the basket for a lay up or dunk.

We collected some video of a player running and dribbling the ball with his right hand, as well as some close up video of the players hand while he bounces the ball while standing.

We set up the video camera on the side of the court so we could watch the player run through the camera field of view. This allows us to see where he bounces the ball as he runs through. If the player ran toward the camera we would be unable to determine how far in front he pushes the ball.

The close up video of the hand will show a good example of how to bounce the ball in the dribble.

1. A correctly inflated basketball should bounce most of the way back up to your hand if you simply dropped it. You only need to push the ball down with enough force to get it back to your hand. Push too hard and the ball will bounce higher than expected and you may lose control.
2. Bounce the ball off your spread fingers. You do not want to push down with your palm. Allow your fingers to feel for the ball as it bounces up and then spread your fingers and push down on the ball for the next bounce. Push down by bending flexing (bending) your wrist.
3. Keep your head up surveying the court and position of your team mates and the opponents. You should do this whether you are running with the ball or simply standing still.
4. Keep your legs slightly bent and be ready to make your move. You do not want to be caught back on your heals as you are dribbling the ball as this makes it easier for an opponent to steal the ball. Be in a position ready to move.
5. Although we do not show this in the video, you should learn to dribble with both hands and on both sides of your body. This will allow you more options when driving toward the basket or preparing for a pass.

Now take a look at our player in the first part of the video as he runs at 3/4 speed while dribbling the ball. Dribbling while running fast can put your opponent off balance and create room for yourself and your team.

Here are a few tips to keep in mind when dribbling and running:

1. Once again, do not look down at the ball. You need to trust that the ball will bounce where you want it. This may be difficult at first but will come with practice. When running and dribbling it is even more important to keep your head up and see the court and be prepared to change direction quickly.
2. Bounce the ball far enough out in front of you so that you do not need to check your run to keep control of the ball. Many a fast break will come to nothing if you need to slow down to get control of the ball.
3. Bounce the ball out a little to the side. If you are dribbling with your right hand keep the ball a little outside and far enough in front of your right leg. If you bounce the ball directly in front of you then you will have more difficulty controlling it as you run. Of course if you are about to cut in toward the basket then you will need to bounce the ball in front of your body, but then you will also be turning your body or switching dribbling hands and will still be keeping ball slight outside your legs.
4. Once again use your fingers to bounce the ball and push it out in front of you. Do not use your palm as you are likely to lose control and probably the ball if you are running fast.

Practice will help you learn any new skill or get better at it. The more you practice the easier you will find the skill as your muscles and body learn what to expect and anticipates the limb movement and muscle action required.

We often say watch video of pros and of yourself and then practice with this in mind. Watching pros allows you to see how it should be done. Watching yourself ensures you know how you compare to these pros. Both are important. If you practiced all day but had no idea what you were doing wrong, you could teach your body to perform the skill incorrectly.

With video technology today there is no reason why you cannot easily assess your own performance. Take a look at previous articles in this website to find more tips on filming yourself or how to do specific skills.

Happy Holidays

Kobe Bryant Perfect Trick Shot Mechanics

Kobe Bryant is one of the three best players in the NBA. However, there can be no doubt that he makes more unbelievable and impossible shots than anyone still playing professionally on a basketball court

Take a look at this one from the LA Lakers Game against the Oklahoma City Thunder. There is no need to try and spot the trick, he is shooting over the backboard.



Kobe can make these incredible shots time after time, because of two important facts.

1. He practices making shots from almost anywhere on the court. To learn how to shoot the ball over the backboard , you need to try it and try it often. It may seem like a waste of time but professional athletes practice trick shots to give themselves more options on the field. Having a practiced trick up your sleeve also confuses your opponent who in the professional leagues has probably seen and knows how to defend the regular shots. Practicing trick shots happens in all sports. Take a look at Roger Federer and his trick shot winner at the US Open in 2009.
2. Practice is important, but what also makes this shot and many other of Kobe's trick shots possible is that he uses flawless shooting technique. Take a closer look at his mechanics in the video above as he shoots.

• Kobe gets up in the air and squares his shoulders so that he is facing the net.
• He keeps his elbow high.
• He paints the ball with his hand, allowing the ball to roll off his fingers rather than pushing it toward the basket.
• He shoots the ball on a high arc, taking advantage of the size of the basketball rim (2X the diameter of the ball).

Take a look at this video of Kobe shooting free throws. Notice that his arm mechanics here are pretty much the same as for the over the backboard shot against the thunder. Shoulders squared to the basket, elbow high, paints the ball with his hand and launches the ball on a high arc.



By using good mechanics for all his shots, Kobe is ready to try any trick shot at any time.

Measuring Your Vertical Leap Using Video Analysis

Before Kobe Bryant or Dwight Howard was considered for a contract in the NBA, they likely had to undergo a series of physical tests and exercises. In fact, most if not all professional and college sports programs require prospective players to complete these "combines", so that they can have a quantifiable way to compare the athletes. Some of the commonly used tests include the 40 yard dash, bench press, and vertical leap. For players in the NBA, the vertical leap test is the most crucial.

The vertical leap test demonstrates how high a player can jump and reach. Ideally, the test shows how high the athlete's center of mass (COM) moves. But since a person's COM is often difficult to determine, the test usually estimates the results by measuring the difference between how high a subject can reach from a standing position, and how high the subject can reach when they jump (either from a stationary or running start). One variation of this test is to simply see how high the athlete can jump and reach. While this latter method measures the maximum height the athlete can touch, it doesn't provide us with how high he/she actually jumped. In simple terms a player with an 9' reach, jumping 1' will reach 10'. A player with a 7' reach, jumping 3' will also reach 10', although it is obvious that the 7' player jumped higher. Simply measuring how high the subject can reach from a standing position before they jump, gives us the additional information needed to calculate how high the athlete jumped.

Professional and college organizations often conduct this test by having the athlete stand next to a tall pole that has little plastic flags extending from it, as shown below. The athlete then jumps and swipes the highest flags he can, and the result is recorded.

If you want to measure your own vertical leap but don't have access to one of these testing devices, you can simply film yourself jumping from a standing position. Besides the basic principles of video analysis (see http://videosportsanalysis.blogspot.com/2009/03/video-analysis-of-sports-101.html), there are two important concepts to keep in mind:

1. In your video clip, you must be able to see an object of known height. This object should also be in the same vertical plane the subject is jumping in. If you're jumping next to a wall, marking a known height on the wall should be good enough. The reason you need to have this information is so the analysis software can scale the distance measurement appropriately (this concept will be shown on the video below).
2. The video analysis software you're using must be able to calculate the distance between two points and be able to use the known height of the object to calibrate the measured distance accordingly; otherwise, the distance between the two points will simply be in units of pixels, which isn't very useful. We need to be able to convert the distance to something like inches or centimeters. If you're interested in finding out more about software packages that offer this type of feature, just let us know and we'll be happy to point you in the right direction.

Below we have a video clip of a subject performing the vertical leap test:



As you can see, we have one point identifying the highest point the subject reached while standing, and one point identifying the highest point the subject reached during the jump. As mentioned in the two concepts above, we have also shown the known height of another object (in this case, the distance from the ground to a point marked on the wall is 37"); and the software automatically uses this information to display the distance between the two points the subject reached in units of inches (23.7").

Compare this subject's results with the likes of NBA superstars Kobe Bryant (38") and Dwight Howard (40"), set to meet in the 2009 NBA Finals. Bryant has been vitually unguardable, draining shots while having defenders' hands in his face, and zipping around opponents with his lightning-quick first step. Howard is a physical force to be reckoned with; players move out of his way when he elevates, to avoid getting "posterized" when he throws down one of his thunderous dunks. It's amazing what these athletes are capable of; and using tests such as the vertical leap allows us to have a more complete understanding of how incredible they really are.

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.

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.