Tuesday, November 15, 2011

"A and Z" Tennis Instruction - How Most Tennis Teachers/Coaches Really See and Understand Your Strokes

Today, let’s take a closer look at the typical still photo-based, tennis stroke analyses that’s presented in today’s media whether that media is in the form of a book, magazine or website.

The vast majority of the analyses of a tennis player’s mechanics are presented in the form of a series of still sequences depicting the ”important” body positions that are achieved by the player at (so-called) “important stages” in the execution of the stroke.

What you see most often in these still photo sequences – comprised of 5 to 6 stills in most cases –are the following positions in the stroke.

First, most conventional stroke analyses start with a still photo of the players’ body positioning when their “unit turn” – the simultaneous rotation of the hips and shoulders – is just about complete (below).

The second photo shows the player’s positioning just around the time when they complete their backswing.

The third photo in the conventional stroke analysis then shows the body positioning around the time the player starts their forward swing to impact.

The fourth photo then shows the player’s positioning at, near, or just after making ball contact.

What should be mentioned here is that before computer-controlled, digital photography, consistently capturing the precise moment of ball impact with clarity and definition was nearly a random event.

This is because the highest capture speed of conventional, film-based SLR camera was a lightning fast, 10 frames per second using the best available motor drives. With today’s digital technologies, even cheaper point-and-shoot, snapshot cameras can capture images at a blinding 40 to 60 frames per second – making it far more likely that ball impact could be clearly captured.

And that’s not even to speak of the clarity and consistency that’s made possible with high-speed video capturing 200+ frames – individual images, in other words – per second or more.

The fifth photo usually shows the player’s positioning somewhere in their follow-through.

And the sixth and final photo ends the conventional stroke analysis by showing the player’s positioning when the entire stroke is completed.

Now, what exactly is the take-home here?

The take-home I would like to leave you with is the fact that conventional, still photo stroke analyses comprised of a whopping six photos was the state-of-the-art when film cameras could only capture images at 10 frames/images per second using a motor drive to advance the film while shooting the player.

With today’s high-speed digital photography and video capabilities, many, many more positions at many, many more stages during the execution of a given stroke can be clearly captured and integrated into the resulting analysis.

In other words, teachers and coaches have access to far more information about the body movements involved in any stroke today.

With most high-speed digital cameras available to consumers today, we can have 20, 40, even 100 TIMES more information about the movements that are performed at any stage of the stroke being analyzed.

In the case of the still sequences of the Federer and Roddick forehand presented here, we could have looked at 236 separate still images for Roger and 199 separate still images for Andy.

How would a 236- or 199-still stroke analysis compare with the traditional 6-still stroke analysis?

Compared to what was possible in the past, a conventional still photo sequence only offers us a very limited perspective of what is going on And with high-speed video, we can see the actual motion – rather than a “freeze-frame” that forces you to extrapolate or guess what movements precede and follow the “frozen moment in time”.

The ability to actually see “motion in motion” is the best, most complete and most unbiased way to begin learning or analyzing your – or someone else’s – strokes. Video overcomes the fragmented nature of still-sequence movement analysis because you can see exactly how players actually move from stage-to-stage – like from backswing to forward swing—in real time (well, highly-slowed down time is really much better).

With the actual stroke motion is captured and made visible in both space and time by video, your brain doesn’t have to “fill in” the motion by reasoning, extrapolating, assuming or guessing about what happens from millisecond to millisecond.

For example, there is no question about how the hands, arms and wrist moved the racket from – using our photo sequence as a reference—the completion of the backswing to the point where the racket has moved 2 feet past the impact point—you will see exactly how on the screen.

Observing strokes in “snapshot” form triggers your brain to do what it does most of the time. That is, your brain “fills in the blank(s)” with its best guess about what movements occurred because there’s no other visible information or evidence available to explain or account for what we see.

So drawing conclusions about what’s happening in your tennis stroke from watching videos—preferably super-slow motion videos—is the way to avoid triggering the brain’s habit of “blank-filling” on your behalf, and also prevents you from being influenced by any bias you may have about stroke mechanics based on your current understanding of them.

You can then base your conclusions on what can actually be seen.*

*N.B.: Now, that doesn’t automatically mean that you’ll avoid bias entirely because, well, your (conceptual) understanding of stroke mechanics may be inherently incorrect or incomplete.

Given the incredible resolution in both space AND TIME that’s possible with high-speed digital video, we can now improve the quality of our still sequences. We can increase the quality of these types of “freeze frame” analyses of stroke mechanics by showing you body positions at different stages of the stroke that weren’t even considered when the best photographers failed to capture impact more than say 10 to 20 percent of the time…

Because their cameras simply weren’t fast enough to capture that fleeting 4 to 7 milliseconds when the ball is in actual contact with the strings.

At only 10 frames per second, the six stroke phases above were the only phases of any stroke anyone could consistently capture and then study.
Today, we see so much more and so, with more information, teachers and coaches could teach you so much more in return.

As my friend puts it,

"Before high-speed video, you – along with your teachers and coaches – could only see the “A” – the backswing – and the “Z”-the follow-through—of any stroke."

So, if that’s the extent of what the teachers and coaches could see, that’s also the extent of what they end up teaching you, because all they know about any stroke is “A AND Z” or “take your racket back like this” followed by “finish like this”.*

All they see and therefore tell you looks like the following:

“Take your racket back like this”…

And then,

“Finish like this”…

Seen and taught this way, all ATP forehands appear darn similar, if not nearly identical to each other, don’t they?

Given what players mostly hear is “A and Z” instruction, my friend then wonders aloud: what about the elements of any stroke that would make up “B to Y”?

Isn’t that a great question? Are there tennis teachers and coaches whose knowledge of any stroke is from “A TO Z” rather than “A AND Z”?

My friend would say that last question is, in his experience, a rhetorical question. And I tend to agree with him on this point.

So, let’s continue looking at the “B to Y” of a topspin forehand and see if there are any insights that can explain the performance differences we see in the real world of tennis…


P.S. *This common “teaching wisdom” reminds me of the South Park episode where the “underpants gnomes” haunt poor Tweak.

In this hilarious episode, the “underpants gnomes” explain the concept behind their business model—i.e. collecting underpants for profit—to the South Park gang as follows:

1) Collect underpants;

2) ? ? ?

3) Make profit.

Isn’t this “underwear collection enterprise” model fundamentally an alternative application of the “A and Z” model used in conventional tennis instruction?

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