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.
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.
In the 100m and 200m track sprinting events, the start can win or lose a race. In the 100m the winning difference is often measured in 100ths of a second, therefore any advantage that can be gained at the start could be crucial.
At the IAAF World Championships next week, Tyson Gay will take on Usain Bolt for the title of worlds fastest man. So far in 2009 both athletes have put up some impressive times and the first meeting between them this year should be fast, close and exciting. Usain Bolt is the Olympic champion and world record holder. We have previously discussed how fast he could possibly run. Tyson Gay is the reigning World Champion and recently ran the 100m in 9.75 seconds at the US Championships.
With both athletes being at the top of their game, victory may be decided by their start. Neither of them is known for their explosive or fast starts. Bolt has an incredibly long stride length and eats up ground with each step while Gay has unmatched leg speed. The start though is crucial and we have therefore decided to look at some video and examine the start.
Below is some front on video of Tyson Gay at the US Championships. We want to focus on his start.
A good start requires that the athlete sets up correctly. Here are some key factors for the set position before the start gun sounds.
The hands are set up on the line and the shoulders and upper body should lean forward over the hands. Track coaches suggest an angle of about 15 degrees (The angle between the shoulders and hands and the vertical). Although we cannot see the angle at which Gay is leaning (this would need a side on view of his start), we can see that he is leaning forward and ready to explode from the blocks.
The angle of the knees in the start position must allow the athlete to push away from the blocks with as much power as possible while at the same time being able to get their feet through to begin running. The optimal bend of the front knee should be around 90 degrees to provide the biggest lever to produce push off. The back leg needs to be bent less than this at about 60 degree so that it is able to still push off hard but will straighten before the front leg and have time to come through for the first step.
Both legs need to push off almost simultaneously at the start of the race. The athlete cannot be sitting back on either his front or back leg at the start.
Tyson Gay sets up well and in this video he explodes from the blocks, pushing off with both legs quickly. Both legs straighten completely, with the rear leg leaving the blocks and starting to drive through before his front leg (left leg) is completely straight.
Gay also uses his arms to explode out of the blocks, as well as maintain good balance. Watch as his right arm drives backward and his left forward. This motion provides extra forward momentum, but it also ensures that as he starts he does not fall over to one side. The arms act as a counter balance to the motion of the legs. In this start his right leg will take the first step on the track and therefore his left arm needs to be forward to balance this motion.
Moving forward to that first right foot step on the track, we can see that Gay's head and chest are still down low. His arms are driving hard and fast. If you pause the video you will see them as a blur. We can also see that his first step is not too long. In fact his head, chest and hips all remain in front of his foot for this first step. This allows him to continue to stay low with his body. If he took a longer first step, it would force his chest up, which would in turn slow down his speed. His chest and head stay down for as many as 16 steps allowing him to lean forward during this start and continue to accelerate.
His start technique looks great here and although we do not know what his reaction time to the gun was, we can see that he was able to accelerate well from the start and this is why he put up such a fast time.
As I looked through more videos on Tyson Gay's start, I came across one from tttjump that suggested that Gay's knee rolls forward at the start. If you study the slow motion of the start in the video above you will see what this means. Gay's front leg (his left) moves forward and down, in fact bends a little more, just after the start and as his hands leave the ground.
The suggestion is that this extra bend of the front knee at the gun, causes a delay in his ability to get off the blocks. On closer examination we can see that his back foot is driving already (straightening) as his front knee "rolls" forward. This may be causing him to push off with less power from his back leg as he may need to slow it down, to give the right leg time to get into a position to start its push off.
From a biomechanical standpoint, this would suggest that Gay's front leg is not bent to the most optimal position to explode out of the blocks. He may be bending it a little more after the start to get more push off power. The split second it takes to bend the knee that little bit more and the small amount of back foot push off power that he may lose, could determine the outcome of the race against a phenom like Usain Bolt.
Once again from the standpoint of biomechanics, this problem could possibly be solved by simply adjusting Tyson Gays starting blocks or position slightly, allowing his front knee to set up in a more optimal position for his starting style.
Of course for this World Championships, it is too late to make any changes and Tyson Gay should provide Usain Bolt some really stiff competition when they hopefully meet in the final in Berlin.
If you will be watching or filming some video of any of the action at the IAAF world championships and would like to share some video for analysis, please let us know.
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.
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