Redefining the spatial consistency in the ball toss of the professional female tennis

[julian]

Redefining the spatial consistency in the ball toss of the professional female tennis serve
Source: International Symposium on Biomechanics in Sports: Conference Proceedings Archive
Issue: volume 32
Pages: 181-185
Language: English
Publication Type: Conference
Publication: International Symposium on Biomechanics in Sports: Conference Proceedings Archive; 2014, Vol. 32, p181-185, 5p
ISSN: 19994168
Georgia Giblin
David Whiteside
Machar Reid
Conference: International Conference of Biomechanics in Sports, At Johnston City, TN
ABSTRACT The objective of this study was to quantify the three-dimensional spatial variability of the ball toss in the female tennis serve and interpret its practical implications. A 500Hz optical motion capture system recorded the ball toss trajectory while eight professional female players performed flat 1st serves. The anteroposterior and lateral variability of ball location was smaller at ball zenith compared with impact. The impact height was the most consistent aspect of the ball toss. Given these findings, the prevailing coaching drills that emphasize consistency appear too stringent. Players should be granted more liberal constraints when rehearsing the ball toss and ball toss drills should retain a racket-ball impact component (as opposed to rehearsing the ball toss in isolation) to refine a consistent impact height.
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[Chas Tennis]

I searched Google Scholar using the title.

https://ojs.ub.uni-konstanz.de/cpa/article/view/6097/5577

pdf

 

[treblings]

so the study concludes, that even female pro players don´t have a perfect ball toss everytime?

 

[makinao]

The archives of all previous conferences can be found here:

https://ojs.ub.uni-konstanz.de/cpa/issue/archive

 

[Raul_SJ]

This study suggests re-examining the common drill whereby students toss and have to land the ball on the racquet. As the figure shows, none of the 5 pro players tosses landed on the racquet.

Although I am not sure of the degree of accuracy with the study's "extrapolated landing locations"...

 

[sureshs]

What if the drill just improves the accuracy so that the toss does not land even further away?

 

[Raul_SJ]

What if the drill just improves the accuracy so that the toss does not land even further away?

As I understand the study, there is considerable left/right and back/front variation in the tossed ball landings (extrapolated landings). But the contact height is consistent. Although the image does not show the impact locations, only the extrapolated tossed ball landings.

So a pro player's toss might veer off to the left/right and back/front, but the impact height is consistent.

But I'm not sure what it is referring to when discussing variability in the zenith and impact.

"The anteroposterior and lateral variability of ball location was smaller at ball zenith compared with impact."

 

[sureshs]

As I understand the study, there is considerable left/right and back/front variation in the tossed ball landings (extrapolated landings). But the contact height is consistent. Although the image does not show the impact locations, only the extrapolated tossed ball landings.

So a pro player's toss might veer off to the left/right and back/front, but the impact height is consistent.

But I'm not sure what it is referring to when discussing variability in the zenith and impact.

"The anteroposterior and lateral variability of ball location was smaller at ball zenith compared with impact."

I didn't get it either. Once the zenith is in a certain place, the subsequent positions of the ball on descent are fixed, and the impact point has to be one of those.

 

[julian]

Shakespeare for you

I didn't get it either. Once the zenith is in a certain place, the subsequent positions of the ball on descent are fixed, and the impact point has to be one of those.

--->quote for you
Shakespeare Quick Quotes

There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
- Hamlet (1.5.167-8), Hamlet to Horatio

your philosophy ] i.e., philosophy (or learning) in general.

The emphasis here should be on "dreamt of", as Hamlet is pointing out how little even the most educated people can explain.

One can imagine happier times when Hamlet and Horatio, studying together at Wittenberg, engaged in heated philosophical debates.

Shakespeare does not expand on the specific nature of Horatio's philosophy, and in the First Folio (1623), the text actually reads "our philosophy." Some editors, such as Dyce, White and Rowe, choose to use "our" instead of "your" (as found in Q2), believing Hamlet is speaking in general terms about the limitations of human thought.

For much more on this passage, please see the full explanatory notes for Hamlet.

 

[julian]

J hook toss

so the study concludes, that even female pro players don´t have a perfect ball toss everytime?

A hook toss should be used for a drill.
The racket has to be moved to the LEFT
Please let me know you saw THIS post.

 

[treblings]

A hook toss should be used for a drill.
The racket has to be moved to the LEFT
Please let me know you saw THIS post.

what´s your point?

 

[julian]

The article

what´s your point?

in US one teaches a J hook toss for a serve.
If you know what this toss is my post is simple:
this toss is NOT perpendicular to the ground
The toss perpendicular to the ground was used in the article.
I object that

 

[julian]

Post #5

what´s your point?

Do you have any opinions about drawing of the post #5?

 

[julian]

ZERO balls landed on the racket

This study suggests re-examining the common drill whereby students toss and have to land the ball on the racquet. As the figure shows, none of the 5 pro players tosses landed on the racquet.

Although I am not sure of the degree of accuracy with the study's "extrapolated landing locations"...

ZERO balls landed on the racket lying on the ground

 

[Raul_SJ]

ZERO balls landed on the racket lying on the ground

I understand that. The tosses landed at various locations, varying to the left/right and back/front (anteroposterior and lateral variability) and the height at impact was consistent.

But what is meant by the following?:

"The anteroposterior and lateral variability of ball location was smaller at ball zenith compared with impact."

The impact point will simply be at some point along the descent path from the zenith. The impact point and zenith have no effect on the landing location.

 

[Chas Tennis]

............................................

"The anteroposterior and lateral variability of ball location was smaller at ball zenith compared with impact."

..................................

I did not read the article so this is my interpretation.

The zenith is the peak of the toss indicating the ball's location into the court and side-to-side (lateral) at the peaks (zeniths). Many balls are measured for statistics. Toss peak heights are not measured.

Next there are a series of similar points for ball location impact.

The impacts are always farther along the ball's trajectories than the peaks. Then if a single ball was located 20 centimeters to the right (of the average) at the peak it would continue along its trajectory and maybe it would be 30 centimeters to the right at impact. (30 cm > 20 cm) Each of the balls would do that, have a smaller distance at peak than at impact. For statistics giving variability the spread at the peaks or zeniths of each ball would always be smaller than the variability giving the impacts.

Draw it from above and draw ball trajectories. Wind would increase the amount of the variability farther.

It's like saying if you aim and shoot a bullet at a target the farther the bullet flies the farther off target it will be.

 

[Raul_SJ]

I did not read the article so this is my interpretation.

The zenith is the peak of the toss indicating the ball's location into the court and side-to-side (lateral) at the peaks (zeniths). Many balls are measured for statistics. Toss peak heights are not measured.

If the peak heights are not measured, how is it possible to extrapolate the toss landing locations?

 

[Chas Tennis]

If the peak heights are not measured, how is it possible to extrapolate the toss landing locations?

The diagram showing landing locations says that they were "extrapolated" landing locations. I believe that they traced the trajectories with cameras....?

What does the report say?

 

[Raul_SJ]

The original wording did not mention "landing locations" but "zeniths".

Weren't the landing locations presented measured? What does the report say?

The landing locations were not actual. The study extrapolated them.

"The polynomial function acted to both filter and also extrapolate the ball trajectory beyond impact, simulating the ball’s trajectory had it not been contacted by the racket"

DISCUSSION:

This study quantified the spatial variability in the ball toss of professional
female tennis players. Predictably, the players in this study did not employ a perfectly repeatable ball toss, but rather placed the ball anywhere inside a finite area of space. This area was approximately cubic at ball zenith and became wider (though vertically smaller) at impact.

The extrapolated landing locations of the ball were even more variable and seemed to challenge the relevance of common drills. Coaches may use these results to reassess their conception of consistency in the ball toss and develop more relevant practice drills

https://ojs.ub.uni-konstanz.de/cpa/article/view/6097/5577

 

[Raul_SJ]

The zenith is the peak of the toss indicating the ball's location into the court and side-to-side (lateral) at the peaks (zeniths). Many balls are measured for statistics. Toss peak heights are not measured.

Next there are a series of similar points for ball location impact.

The impacts are always farther along the ball's trajectories than the peaks.

I think I follow you up to here. The toss traces a three dimensional parabolic path, both into the court, and along the baseline.

Then if a single ball was located 20 centimeters to the right (of the average) at the peak it would continue along its trajectory and maybe it would be 30 centimeters to the right at impact.

I don't follow this. "ball was located 20 centimeters to the right".
"located" meaning where the ball landed on the court?

 

[julian]

A foot and a half

I think I follow you up to here. The toss traces a three dimensional parabolic path, both into the court, and along the baseline.



I don't follow this. "ball was located 20 centimeters to the right".
"located" meaning where the ball landed on the court?

I think data are strange at the best.
A foot and a half INSIDE of the court would be much more likely

 

[Chas Tennis]

I don't follow this. "ball was located 20 centimeters to the right".
"located" meaning where the ball landed on the court?

You toss 100 balls. At the peak there is an x,y, z coordinate for each ball.
To get an average for the 100 balls you average the x,y z of all balls and get an average x, avg y, avg z of the 100 locations.

Each ball's x,y & z can be referenced to that average point. For example, one ball was 20 cm to the right of the avg x,y, z of the peak. To work with variances you calculate average of a number of data points, compute an average and then relate points to that average. A large variance means poor accuracy and a small variance indicates high accuracy.

Let's say the sides of these represent distance x lateral (right-left), across the court and y the distance into the court

x __ .................... y |

 

[Raul_SJ]

From 100 tosses, calculate the average peak point xyz coordinate. Let's call it the "Average Peak Coordinate".

From these 100 tosses, do we also need to calculate the "Average Impact Coordinate"?

Then if a single ball was located 20 centimeters to the right (of the average) at the peak it would continue along its trajectory and maybe it would be 30 centimeters to the right at impact. (30 cm > 20 cm).

"30 centimeters to the right at impact" meaning that this single ball was to the right of the "Average Peak Coordinate" at impact? Or to the right of the "Average Impact Coordinate"?