Interactive Forum April 2010: More New High Speed Footage! Ljubicic Backhands

[johnyandell]

We had an incredible experience with our new high speed filming protocols at Indian Wells, and as I've written, we will be launching a next generation High Speed Archive later this year that will take video analysis in tennis up two levels (or three or four...).

One of the surprises of the tournament was the re-emergence of Ivan Ljubicic who came out of nowhere to win his first masters event, defeating Rafael Nadal and Andy Roddick, among others.

So here is another preview of this high def footage, shot at an amazing 500 frames per second, and available nowhere else in the world: Ivan's first fearsome backhand--a slice and then two topspin drives.

Let us know now if this looks good or has too much information for you, and maybe we'll try to dial it back. Just kidding.

Ljubicic Backhands

[johnyandell]

Quicktime version

Ljubicic Backhands

[llll]

WOWWWWWWW. awesome video John. keep up your great work

[johnyandell]

OK guys what do you make of:

1. The differences in the grip between the slice and the drives?

2. His unit turns?

3. What about the step pattern on the second drive?

4. His hitting arm position?

5. The wiper on the second drive?

Or at this point is this all self-explanatory in light of the frameworks we've already created?

[jryle1]

The video footage is incredible!! What other players did you get to film?

[jackgordon]

little finger

Mr. Ljubicic lifts his right little finger off the racket handle during his shot preparation. I suppose this might be to ensure a softer grip.

I'm not sure this would have been quite so noticeable without the hyper-slowmo.

[brentabel]

IL's little finger

Good observation Jack. That was the first thing that caught my eye and there's no question it's got to have been trained to help him not apply the death grip.

So many players have the proper set up, footwork, grip, etc., but if there's too much grip tension, the swing speed and timing gets thrown out the window. Brent

[johnyandell]

Lots of others--Nadal, Fed, Jo Willie, Djok, Roddick, more.

Now who thinks they can figure out how to calculate the spin by watching the markings on the ball turn over at 500 frames/sec?

[bmonsour]

How about 8500 rpm

I started with the incoming ball at the 1:19 mark on the video. I first counted the rotations of the ball (as best I could) from that point until the point where I believed Ivan made contact with the ball (around 1:23). I counted 33 rotations. I then went back to the start of the 1:19 mark and advanced one frame at a time, counting the frames until I got to Ivan's contact point again (I counted 116 frames).

So, we then have:

116 frames @ 500 frames/sec = .232 sec

taking the ratio of 33 rotations to .232 seconds, gives you 142 rotations per second, or 8,534 rotations per minute.

Does that work out to what you get?

[johnyandell]

8000rpm would be truly amazing. Actually there is a bit of a trick in the question.

The ball is marked on both sides.

Here is how we did the calculation (actually later we automated this with a piece of proprietary software).

Go to the contact on the first drive backhand. The ball labeling is facing the camera. Now just advance frame by frame. At about frame 7 or 8 you'll see the label on the other side of the ball--so it's turned half way over. At about frame 15 the first label comes up meaning one revolution.

You can keep going and you'll see it stays about 15 frames per revolution as the ball flight continues.

So 1 rev = 15 frames. 500 frames per second means that in one second there were about 33 revolutions.

15/500 = 1/x = 33

So to get the rpms you just multiply by 60 and that's almost exactly 2000rpms.

Still a lot of work on the ball!

[bmonsour]

I thought 8500 sounded a bit high. I didn't realize that the ball was marked on both sides. I just thought that it was sometimes blurry, when in fact it was probably the less intensely marked side.

You're right, 2000 rpm is some serious spin.

Great work!

[johnyandell]

Next month you can try your new math on Nadal's forehand...

[sejsel]

First of all, good job, John, just keep on keepin' on!

OK guys what do you make of:

1. The differences in the grip between the slice and the drives?

Classic. School example of switching between continental/neutral on slice and towards heavier (or similar, this is never fixed, or there could be and can be a certain amount of small adjustments depending on a situation) eastern backhand grip. (Wonder how McEnroe produced all of his shots with continental).

2. His unit turns?

Looks really (again) classic.

3. What about the step pattern on the second drive?

Looks in accordance with what is natural for one hander when pulled somewhat more wide on the backhand side, this has been referred too in articles on tennisplayer.net.

What is really interesting (to me) is what happens after the shot, in the recovery phase. He lifts off the front foot, the back foot continues in the direction of the movement, but front foot in the meanwhile lands slightly in the opposite direction, while the back foot pushes also back towards the center of the court (baseline).

(Do correct me if this description of the sequence is off at some point).

You probably get the point on why this is interesting, it can be seen in Federer's frames (sequences) at tennisplayer.net, and elsewhere.

Very economic, (can be described as "advanced") step sequence, since it contributes to faster recovery.

4. His hitting arm position?

5. The wiper on the second drive?

Or at this point is this all self-explanatory in light of the frameworks we've already created?

Last two points are best characterized by John's remark at the end of the last quote.

Although, the wiper on the second drive looks more (due to its', or racquet head's amplitude throughout the follow-through) like a slight variation on classic, conservative one hander follow-through.

[johnyandell]

Well said on all points.