TennisSpeed Racket Face Tilt Displays

[Chas Tennis]

Forehand drive racket face tilts typical of ATP players.

Often some tennis strokes have a flaw with the tilt of the racket face just before impact. Side camera views show the racket face tilt just before impact.

TennisSpeed provided some of the best displays seen on the internet.
Yellow is before impact.
Green is impact.
Red is after impact.

There is a detailed TennisSpeed video on how the lines were applied to the forehand videos. If anyone finds that TennisSpeed video, please post.

Part 1 What is the Racket Really Doing in the Impact Zone?

TennisSpeed Research: A Roadmap to a Hall-of-Fame Forehand - Part 1: What is the Racket Really Doing in the Impact Zone?

tennisspeedresearch.blogspot.com

 

[ballmachineguy]

Often tennis strokes have a flaw with the tilt of the racket face just before impact.

If so, the player either has the wrong concept of the stroke or just the wrong grip.

 

[Morch Us]

have a flaw with the tilt of the racket face

what?
I don't see a flaw in the diagrams.

The racquet face remains same as impact around 4 lines before impact (which helps with consistency).
The racquet face closes after impact because of the ball. Players unknowingly always hits slightly at the lower half, because that "feels" right. When they hit at upper half it "feels" wrong (feels mishit), and the ball flies high.

 

[Chas Tennis]

If anyone would like to apply these racket face colored lines to your stroke videos, Kinovea can do this along with many other capabilities. Single frame advance, apply lines to racket face positions, decide how many frames to display, label, etc. Kinovea is a free, open source video processing application that is perfect for athletic applications.

Kinovea has a count down timer, that is ideal for making each stroke video into a timeline for many sub-motions of the stroke. Impact is at 0 milliseconds. This video has 4 second pauses to read the captions, for longer times click on video.

To single frame on Youtube, stop video, go full screen and use the period & comma keys.

 

[10sbeast888]

Forehand drive racket face tilts typical of ATP players.

Often some tennis strokes have a flaw with the tilt of the racket face just before impact. Side camera views show the racket face tilt just before impact.

TennisSpeed provided some of the best displays seen on the internet.
Yellow is before impact.
Green is impact.
Red is after impact.

There is a detailed TennisSpeed video on how the lines were applied to the forehand videos. If anyone finds that TennisSpeed video, please post.

Part 1 What is the Racket Really Doing in the Impact Zone?

TennisSpeed Research: A Roadmap to a Hall-of-Fame Forehand - Part 1: What is the Racket Really Doing in the Impact Zone?

tennisspeedresearch.blogspot.com

@user92626 - read the following slowly as there will be a quiz lol.

see the yellow lines above..... the first line is pad the dog, or face to the ground, and during the swing the yellow line gradually opens.

NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.

write this on the blackboard 100 times, this will fix your fh.

you look at the 4.0 and below, and even many 4.5s even up to some 5.0s, any time the above is breached, the shot becomes garbage.

if you attack the ball on edge, and delay the open of the face, your good.

I tell my guys to have the sensation that the strings are hidden from the ball, until 8 inches from impact.

in reality of course as you can see in the pro's pics above, the strings can see the ball long before impact, but in order to over-correct most amateurs problem of attacking the ball with an open face, that's the mental picture I tell my guys to use.

 

[ballmachineguy]

@user92626 - read the following slowly as there will be a quiz lol.

see the yellow lines above..... the first line is pad the dog, or face to the ground, and during the swing the yellow line gradually opens.

NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.

write this on the blackboard 100 times, this will fix your fh.

you look at the 4.0 and below, and even many 4.5s even up to some 5.0s, any time the above is breached, the shot becomes garbage.

if you attack the ball on edge, and delay the open of the face, your good.

I tell my guys to have the sensation that the strings are hidden from the ball, until 8 inches from impact.

in reality of course as you can see in the pro's pics above, the strings can see the ball long before impact, but in order to over-correct most amateurs problem of attacking the ball with an open face, that's the mental picture I tell my guys to use.

????

 

[10sbeast888]

????

yes sir.

 

[Chas Tennis]

@user92626 - read the following slowly as there will be a quiz lol.

see the yellow lines above..... the first line is pad the dog, or face to the ground, and during the swing the yellow line gradually opens.

NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.

write this on the blackboard 100 times, this will fix your fh.

you look at the 4.0 and below, and even many 4.5s even up to some 5.0s, any time the above is breached, the shot becomes garbage.

if you attack the ball on edge, and delay the open of the face, your good.

I tell my guys to have the sensation that the strings are hidden from the ball, until 8 inches from impact.

in reality of course as you can see in the pro's pics above, the strings can see the ball long before impact, but in order to over-correct most amateurs problem of attacking the ball with an open face, that's the mental picture I tell my guys to use.

?

I was mixed up between terms of position and terms of motion for a few years. But there are two usages going on even in biomechanics publications.

Position - Angle of Racket Open or Closed (degrees). My defintions of open and closed are related to gravity and the vertical and the side of the racket that the ball hits. If open the highest edge of the racket is farther from the incoming ball. If closed the highest edge of the racket is closest to the incoming ball. The TennisSpeed displays show exactly this. These racket face tilts affect the important Projection Angle (elevation) of the ball and affect ball out or in.

Motion - Angle of Racket Face Closing or Opening (degrees per second). There is another use of the terms 'opening' and 'closing' for motions.

The same position vs motion usage applies to Joint Positions and Joint Motions and it can be confusing.

An elbow joint - at the same time - may be in a flexed position but the elbow joint may be extending in motion (moving toward maximum extension). As - bend your elbow all the way and then straighten it out.

To see defined joint positions for angles, Google, how to measure elbow flexion angle Youtube. "0 degrees" is defined.

For motions

Anatomical terms of motion - Wikipedia

en.wikipedia.org

Example, I would say that Nadal is opening the racket face as he starts toward the ball, but his racket face is held at a constant closed angle approaching impact. See Nadal picture in OP.

Example, for serving when starting the forward swing, the shoulder joint may be at an angle of External Shoulder Rotation (with pre-stretched ISR muscles) but at the same time be doing Internal Shoulder Rotation.

Of course, all joints are in a position, usually described by an angle. But during tennis strokes that angle may be impossible to measure, since measuring joint angles is done only with a prescribed process. See measuring Youtube.

 

[sureshs]

NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.
NOWHERE DURING THE SWING, IS THE YELLOW LINE ANGLE MORE OPEN THAN AT IMPACT.

write this on the blackboard 100 times, this will fix your fh.

FOR THE NADAL IMAGE, THE YELLOW LINE JUST BEFORE THE GREEN LINE (IMPACT) IS MORE OPEN THAN THE GREEN LINE.
FOR THE NADAL IMAGE, THE YELLOW LINE JUST BEFORE THE GREEN LINE (IMPACT) IS MORE OPEN THAN THE GREEN LINE.
FOR THE NADAL IMAGE, THE YELLOW LINE JUST BEFORE THE GREEN LINE (IMPACT) IS MORE OPEN THAN THE GREEN LINE.

 

[10sbeast888]

FOR THE NADAL IMAGE, THE YELLOW LINE JUST BEFORE THE GREEN LINE (IMPACT) IS MORE OPEN THAN THE GREEN LINE.
FOR THE NADAL IMAGE, THE YELLOW LINE JUST BEFORE THE GREEN LINE (IMPACT) IS MORE OPEN THAN THE GREEN LINE.
FOR THE NADAL IMAGE, THE YELLOW LINE JUST BEFORE THE GREEN LINE (IMPACT) IS MORE OPEN THAN THE GREEN LINE.

lol... that could just be the green line timing is a bit late, as rafa did hit lower on the face, evidenced by the severe closing after the impact.

 

[10sbeast888]

Forehand drive racket face tilts typical of ATP players.

Often some tennis strokes have a flaw with the tilt of the racket face just before impact. Side camera views show the racket face tilt just before impact.

TennisSpeed provided some of the best displays seen on the internet.
Yellow is before impact.
Green is impact.
Red is after impact.

There is a detailed TennisSpeed video on how the lines were applied to the forehand videos. If anyone finds that TennisSpeed video, please post.

Part 1 What is the Racket Really Doing in the Impact Zone?

TennisSpeed Research: A Roadmap to a Hall-of-Fame Forehand - Part 1: What is the Racket Really Doing in the Impact Zone?

tennisspeedresearch.blogspot.com

I am going to hijack the thread a little if ok with @Chas Tennis although the concepts I want to introduce are related.

- low contact... this was discussed before and ended with 'agree to disagree'... but notice the few yellow lines before the impact are rising, indicating the rising racket head. certainly the lower you hit on the face the longer the acceleration runway, and the pros after hitting millions of balls already know that's their optimal contact spot, which is low.

- question is how to achieve that, other than hitting millions of balls like the pros.
-- intentionally hitting low? seems work on the 1hbh, as the micro adjustment with pronation can compensate the late opening;
-- but doesn't seem to quite work with the fh, or does it... would like to get input from others. (this maybe something you never think about, then no worries, or experiment and see what happens.

- 'intentional shank'... I mentioned a couple of times and nobody could believe this could possibly work, but I used on a couple of guys it works nicely. intentionally shank the ball with the bottom edge, even below the lowest main... you'll hit the most nasty 1hbh ever... and seems to work with the fh as well, which is surprising. -- the shank won't actually happen, but seems the brain uses this swing thought to keep the face closed to the maximum duration and opening up just in time to produce the most nasty ball.

thoughts..

 

[Chas Tennis]

I am going to hijack the thread a little if ok with @Chas Tennis although the concepts I want to introduce are related.

- low contact... this was discussed before and ended with 'agree to disagree'... but notice the few yellow lines before the impact are rising, indicating the rising racket head. certainly the lower you hit on the face the longer the acceleration runway, and the pros after hitting millions of balls already know that's their optimal contact spot, which is low.

- question is how to achieve that, other than hitting millions of balls like the pros.
-- intentionally hitting low? seems work on the 1hbh, as the micro adjustment with pronation can compensate the late opening;
-- but doesn't seem to quite work with the fh, or does it... would like to get input from others. (this maybe something you never think about, then no worries, or experiment and see what happens.

- 'intentional shank'... I mentioned a couple of times and nobody could believe this could possibly work, but I used on a couple of guys it works nicely. intentionally shank the ball with the bottom edge, even below the lowest main... you'll hit the most nasty 1hbh ever... and seems to work with the fh as well, which is surprising. -- the shank won't actually happen, but seems the brain uses this swing thought to keep the face closed to the maximum duration and opening up just in time to produce the most nasty ball.

thoughts..

Pictures were shown especially to show the tilt on the racket head just before impact. Yellow lines. The video camera recording rate was not that fast, maybe 240 fps. Impact lasts about 4 milliseconds. At 240 fps, a frame is recorded every 4.1 milliseconds. To observe impacts the frame rate to catch the ball often close to but before 'first touch' takes higher frame rates than about 240 fps. 2000 would be good, 1000 might do getting 4 frames during ball string contact, but with 240 I would avoid saying things about contact time. If I saw a few parallel yellow lines or forehands, I believe that those represent racket tilt just before impact, because the yellow line change slowly. But I don't know exactly when impact occurred when I see the green line from a 240 fps video. If you want that, record at higher frame rates. You get informative yellow lines but the green line will vary between forehands depending on when the frame was captured. That is why I always say to get the racket tilt just before impact, use the closest yellow line before the green line.

Hitting Low on Racket Face. On the forehand, years ago, I had believed that the ball was most often hit in the bottom half of the racket face, say, below the racket centerline for a near horizontal ball trajectory. I tried to confirm my belief by viewing ATP videos. It appeared to not be an obvious or large enough observation to make. I did not want to study impact heights and all other variables so I decided that I would stop saying most ATP players hit the ball in the bottom half of the racket face. Careful measurement are needed and my quick look did not show off center line hits for ATP players. (centerline through handle & string face).

Ball rolling on face of racket. I believe that @John Yandell has often said that the ball does not roll on the strings. I interpreted that as for hard ATP topspin drives where the ball distorts/flattens and the strings cup. I have seen that brief flattening of the ball in some high paced strokes and believe that occurs. I also don't believe the ball rolls when it flattens and believe for strong forehand drives that it does flatten. Camera motion blur may prevent observing the flattening of the ball for the average high speed camera. ? Very fast shutter speeds should be used. 1/2000 sec shutter may not be fast enough to catch the brief flattening. ?

Tennis Elbow and 1HBH. In 2012 or 2011 there was a publication on the 1HBH. It attributed off center line impacts as a factor causing Tennis Elbow. Tennis biomechanics researcher Duane Knudson, who attributed amatuer's flexed wrists as a factor for causing TE some years earlier, wrote a publication that seemed be favorable to the 2011or 12 publication and its result. I had observed the backhands of ATP players and Justine Henin and observed that most high level 1HBHs used extended wrists and not flexed wrists. Just look at 10 playerss. I do not know where the cause of Tennis Elbow is today. I posted on this issue and the publications. You need to read the publication on off center hits and look at ATP one hand backhand videos to see the flexed vs extended wrist issue for the 1HBH.

 

[10sbeast888]

Pictures were shown especially to show the tilt on the racket head just before impact. Yellow lines. The video camera recording rate was not that fast, maybe 240 fps. Impact lasts about 4 milliseconds. At 240 fps, a frame is recorded every 4.1 milliseconds. To observe impacts the frame rate to catch the ball often close to but before 'first touch' takes higher frame rates than about 240 fps. 2000 would be good, 1000 might do getting 4 frames during ball string contact, but with 240 I would avoid saying things about contact time. If I saw a few parallel yellow lines or forehands, I believe that those represent racket tilt just before impact, because the yellow line change slowly. But I don't know exactly when impact occurred when I see the green line from a 240 fps video. If you want that, record at higher frame rates. You get informative yellow lines but the green line will vary between forehands depending on when the frame was captured. That is why I always say to get the racket tilt just before impact, use the closest yellow line before the green line.

Hitting Low on Racket Face. On the forehand, years ago, I had believed that the ball was most often hit in the bottom half of the racket face, say, below the racket centerline for a near horizontal ball trajectory. I tried to confirm my belief by viewing ATP videos. It appeared to not be an obvious or large enough observation to make. I did not want to study impact heights and all other variables so I decided that I would stop saying most ATP players hit the ball in the bottom half of the racket face. Careful measurement are needed and my quick look did not show off center line hits for ATP players. (centerline through handle & string face).

Ball rolling on face of racket. I believe that @John Yandell has often said that the ball does not roll on the strings. I interpreted that as for hard ATP topspin drives where the ball distorts/flattens and the strings cup. I have seen that brief flattening of the ball in some high paced strokes and believe that occurs. I also don't believe the ball rolls when it flattens and believe for strong forehand drives that it does flatten. Camera motion blur may prevent observing the flattening of the ball for the average high speed camera. ? Very fast shutter speeds should be used. 1/2000 sec shutter may not be fast enough to catch the brief flattening. ?

Tennis Elbow and 1HBH. In 2012 or 2011 there was a publication on the 1HBH. It attributed off center line impacts as a factor causing Tennis Elbow. Tennis biomechanics researcher Duane Knudson, who attributed amatuer's flexed wrists as a factor for causing TE some years earlier, wrote a publication that seemed be favorable to the 2011or 12 publication and its result. I had observed the backhands of ATP players and Justine Henin and observed that most high level 1HBHs used extended wrists and not flexed wrists. Just look at 10 playerss. I do not know where the cause of Tennis Elbow is today. I posted on this issue and the publications. You need to read the publication on off center hits and look at ATP one hand backhand videos to see the flexed vs extended wrist issue for the 1HBH.

Oscar W talked about hitting low on the face. the theory holds water, due to the extra runway and the extra power from opening the racket face. anyone can try it the court. try to shank the ball on the lower edge below the lowest main. you will have jaw dropping results.

the ball rolls. it's been established.

the pros have neutral wrist mostly at impact. a neutral wrist making a fist looks like extended but it's not... anyone who can actually hit a 1hbh will know... extended wrist = open face = shot becomes garbage.

 

[user92626]

It's hard enough to contact the ball solidly. Im not gonna try to hit low on the face.

There's other low hanging fruits to pick.

For instance, can you guys discuss the swing path that our body can naturally produce MOST POWERFULLY?

Start from how you grip & support the racket per the swing path of your choice.

To how you engage the chest muscles? Etc Would fly machine workout help ?

 

[Chas Tennis]

Oscar W talked about hitting low on the face. the theory holds water, due to the extra runway and the extra power from opening the racket face. anyone can try it the court. try to shank the ball on the lower edge below the lowest main. you will have jaw dropping results.

the ball rolls. it's been established.

the pros have neutral wrist mostly at impact. a neutral wrist making a fist looks like extended but it's not... anyone who can actually hit a 1hbh will know... extended wrist = open face = shot becomes garbage.

Did you earlier post an Oscar W video and then it was removed? I was looking for that.

I believe that he demonstrates the 1HBH with little uppermost body turn or chest press. ? I'd like to see it again. He and I don't agree on chest press.
____________________________________________________________________________

Pick some 1HBH ATP players and we can look at wrist angles. Videos.
OR
Google: one hand backhand ATP pictures

My thread One Hand Backhand - Waht Force to Start Forward Swing? (Has many videos.)

 

[10sbeast888]

It's hard enough to contact the ball solidly. Im not gonna try to hit low on the face.

There's other low hanging fruits to pick.

For instance, can you guys discuss the swing path that our body can naturally produce MOST POWERFULLY?

Start from how you grip & support the racket per the swing path of your choice.

To how you engage the chest muscles? Etc Would fly machine workout help ?

it's hard to believe... you will hit cleaner balls by intentionally shanking it, than trying to hit the sweet spot.

work on control first... with dog-pull-impact you need to hit 100 balls in the same spot say 3ft inside both lines without fail.. power will come naturally.

 

[10sbeast888]

Did you earlier post an Oscar W video and then it was removed? I was looking for that.

He demonstrates the 1HBH with little uppermost body turn or chest press. I'd like to see it again. He and I don't agree on chest press.
____________________________________________________________________________

Pick some 1HBH ATP players and we can look at wrist angles. Videos.
OR
Google: one hand backhand ATP pictures

My thread One Hand Backhand - Waht Force to Start Forward Swing? (Has many videos.)

like i said the 1hbh wrist is neutral.. looks extended because of the grip.. may have to extend in some situations like picking up a low ball, but that's not the norm.

 

[Chas Tennis]

like i said the 1hbh wrist is neutral.. looks extended because of the grip.. may have to extend in some situations like picking up a low ball, but that's not the norm.

Sorry. That is a forehand video. I meant the 1HBH video that looks similar.

This is getting off topic.....

If some readers would look at videos from the side camera view they would know the racket face is tilted closed in the ATP forehand drive and could see how it is for their drives.

 

[10sbeast888]

Sorry. That is a forehand video. I meant the 1HBH video that looks similar.

I have never seen him talking about hitting low on the 1hbh.

but it would make sense for the same reason. - extra runway for acceleration, extra power on the face opening.

 

[Chas Tennis]

I have never seen him talking about hitting low on the 1hbh.

but it would make sense for the same reason. - extra runway for acceleration, extra power on the face opening.

Here are the Tennis Elbow references that I mentioned.

I have followed some of Knudson's publications on Tennis Elbow. One point that he had discussed earlier and emphasized was the wrist joint angle during the stroke and at impact, extended for the one hand backhand. When I look at high level one hand backhands, most drive impacts are with the wrist extended. I don't know how wrist angle relates to ball height.
https://www.google.com/search?q=one...S_iKrPAhVh0YMKHa_7BYkQsAQIHQ&biw=1063&bih=685

This Tennis Elbow update (2014) by Knudson does not mention the wrist angle but hits off-center from the longitudinal axis of the racket.
http://www.ptrtennis.org/secured/tp/articles/en/jf14-knudson.pdf

Here is the King publication that Knudson refers to.
http://www.sciencedirect.com/science/article/pii/S002192901200067X
________________________________________________________________________

Tendon injuries can quickly lead to Tendinosis, defectively healed tendon tissue that may never be right again. It is important when first getting the injury to stop stressing it immediately, including during a tennis match. See a well qualified Dr for a firm diagnosis. Plan on months of no tennis or stress to allow optimal tendon healing.

Study this injury before you are injured. Notice the number of players wearing elbow braces. Don't play and see how you do!! Tendinosis develops quickly.

See thread - Tendon Injury Nuthouse.

 

[10sbeast888]

Here are the Tennis Elbow references that I mentioned.

tennis elbow has nothing to do with flex/extended wrist... you can get it either way by arming the ball..

as a matter of fact I'd argue it's LESS likely to get TE with flex... the way I hit it, and the way I teach my guys -

the wrist is completely passive, the arm is wet noodle.... the elbow takes no impact at all as the grip pressure is only 1 or 2 out of 10.

when the wrist is passive, it just flexes due to gravity.

an extended wrist is a muscled wrist... that tension will contribute to TE.

 

[Chas Tennis]

tennis elbow has nothing to do with flex/extended wrist... you can get it either way by arming the ball..

as a matter of fact I'd argue it's LESS likely to get TE with flex... the way I hit it, and the way I teach my guys -

the wrist is completely passive, the arm is wet noodle.... the elbow takes no impact at all as the grip pressure is only 1 or 2 out of 10.

when the wrist is passive, it just flexes due to gravity.

an extended wrist is a muscled wrist... that tension will contribute to TE.

I base my views on tennis strokes mostly on ATP video observations. I can observe the angle of the wrist but not the muscle forces or feelings.

A flexed wrist lenghtens the muscle to the injured tendon(s?) attached at the elbow for Tennis Elbow. An extended wrist shortens that muscle. It would seem a flexed wrist might stretch the tendon and be more vulnerable - especially at impact. ? My personal consideration.

Do you have references for your Tennis Elbow views?

Have you observed 10 ATP one hand backhand players and observed their wrists during the 1HBH and at impact? I have and most ATP 1HBH drive wrists are extended by a high percent.

Example of extended wrist. Include stopping video on impacts

To single frame on Youtube, go full screen and use the period & comma keys.

Here is the publication that says off centerline impacts on the racket face may be a factor.

The effects of ball impact location and grip tightness on the arm, racquet and ball for one-handed tennis backhand groundstrokes

A torque-driven, 3D computer simulation model of an arm–racquet system was used to investigate the effects of ball impact location and grip tightness …

www.sciencedirect.com

From abstract
".....Simulations showed that during off-centre impacts below the longitudinal axis of the racquet, the wrist was forced to flex up to 16° more with up to six times more wrist extension torque when compared to a centre impact simulation....."
tendon
I would interpret that the "wrist extention torque" would pull on the injured tendon of Tennis Elbow.

This publication should be considered before deliberately doing off centerline impacts with 1HBH.

Observing ATP racket face hits would also be useful because I do not recall ever hearing of much Tennis Elbow in the ATP 1HBHs. How many ATP 1HBH hits are off racket centline and by how much?

Dimetrov is the only 1HBH that I have seen in a flexed wrist picture. Here's a more recent video, excellent quality video for analysis.

I would call Dimetrov's wrist angle neutral to flexed a little. Other ATP players have more wrist extension.

Feel Tennis Video

Average tennis players with 1HBHs would not be aware of wrist flexed or extended. Knudson discussed this issue a lot and also observed that pro players had less Tennis Elbow than amatuer players. See Knudson publciations in the late 1990's and Knudson's Biomechanics book on tennis (very good book).

The technique of the OP could be used to color the wrist angles to determine what is true for the 1HBH.

 

[Chas Tennis]

A recent article by TennisSpeed tells us about the great Casio F-1 high speed cameras with extremely fast shutter speeds - down to 25 microseconds for my Ex-FH100. You can still buy these cameras used.

TennisSpeed Research

tennisspeedresearch.blogspot.com

 

[10sbeast888]

I base my views on tennis strokes mostly on ATP video observations. I can observe the angle of the wrist but not the muscle forces or feelings.

A flexed wrist lenghtens the muscle to the injured tendon(s?) attached at the elbow for Tennis Elbow. An extended wrist shortens that muscle. It would seem a flexed wrist might stretch the tendon and be more vulnerable - especially at impact. ? My personal consideration.

Do you have references for your Tennis Elbow views?

Have you observed 10 ATP one hand backhand players and observed their wrists during the 1HBH and at impact? I have and most ATP 1HBH drive wrists are extended by a high percent.

Example of extended wrist. Include stopping video on impacts

To single frame on Youtube, go full screen and use the period & comma keys.

Here is the publication that says off centerline impacts on the racket face may be a factor.

The effects of ball impact location and grip tightness on the arm, racquet and ball for one-handed tennis backhand groundstrokes

A torque-driven, 3D computer simulation model of an arm–racquet system was used to investigate the effects of ball impact location and grip tightness …

www.sciencedirect.com

From abstract
".....Simulations showed that during off-centre impacts below the longitudinal axis of the racquet, the wrist was forced to flex up to 16° more with up to six times more wrist extension torque when compared to a centre impact simulation....."
tendon
I would interpret that the "wrist extention torque" would pull on the injured tendon of Tennis Elbow.

This publication should be considered before deliberately doing off centerline impacts with 1HBH.

Observing ATP racket face hits would also be useful because I do not recall ever hearing of much Tennis Elbow in the ATP 1HBHs. How many ATP 1HBH hits are off racket centline and by how much?

Dimetrov is the only 1HBH that I have seen in a flexed wrist picture. Here's a more recent video, excellent quality video for analysis.

I would call Dimetrov's wrist angle neutral to flexed a little. Other ATP players have more wrist extension.

Feel Tennis Video

Average tennis players with 1HBHs would not be aware of wrist flexed or extended. Knudson discussed this issue a lot and also observed that pro players had less Tennis Elbow than amatuer players. See Knudson publciations in the late 1990's and Knudson's Biomechanics book on tennis (very good book).

The technique of the OP could be used to color the wrist angles to determine what is true for the 1HBH.

wrist position is neutral.

flexsion to extension actually contributes to RHS. staying at extention = loss of power.

stretched muscle is not injury risk. every shot is hit with SSC.

the average player should not think flexion/extention... they should think relaxation.

 

[ratherlosethanpush]

Pictures were shown especially to show the tilt on the racket head just before impact. Yellow lines. The video camera recording rate was not that fast, maybe 240 fps. Impact lasts about 4 milliseconds. At 240 fps, a frame is recorded every 4.1 milliseconds. To observe impacts the frame rate to catch the ball often close to but before 'first touch' takes higher frame rates than about 240 fps. 2000 would be good, 1000 might do getting 4 frames during ball string contact, but with 240 I would avoid saying things about contact time. If I saw a few parallel yellow lines or forehands, I believe that those represent racket tilt just before impact, because the yellow line change slowly. But I don't know exactly when impact occurred when I see the green line from a 240 fps video. If you want that, record at higher frame rates. You get informative yellow lines but the green line will vary between forehands depending on when the frame was captured. That is why I always say to get the racket tilt just before impact, use the closest yellow line before the green line.

Hitting Low on Racket Face. On the forehand, years ago, I had believed that the ball was most often hit in the bottom half of the racket face, say, below the racket centerline for a near horizontal ball trajectory. I tried to confirm my belief by viewing ATP videos. It appeared to not be an obvious or large enough observation to make. I did not want to study impact heights and all other variables so I decided that I would stop saying most ATP players hit the ball in the bottom half of the racket face. Careful measurement are needed and my quick look did not show off center line hits for ATP players. (centerline through handle & string face).

Ball rolling on face of racket. I believe that @John Yandell has often said that the ball does not roll on the strings. I interpreted that as for hard ATP topspin drives where the ball distorts/flattens and the strings cup. I have seen that brief flattening of the ball in some high paced strokes and believe that occurs. I also don't believe the ball rolls when it flattens and believe for strong forehand drives that it does flatten. Camera motion blur may prevent observing the flattening of the ball for the average high speed camera. ? Very fast shutter speeds should be used. 1/2000 sec shutter may not be fast enough to catch the brief flattening. ?

Tennis Elbow and 1HBH. In 2012 or 2011 there was a publication on the 1HBH. It attributed off center line impacts as a factor causing Tennis Elbow. Tennis biomechanics researcher Duane Knudson, who attributed amatuer's flexed wrists as a factor for causing TE some years earlier, wrote a publication that seemed be favorable to the 2011or 12 publication and its result. I had observed the backhands of ATP players and Justine Henin and observed that most high level 1HBHs used extended wrists and not flexed wrists. Just look at 10 playerss. I do not know where the cause of Tennis Elbow is today. I posted on this issue and the publications. You need to read the publication on off center hits and look at ATP one hand backhand videos to see the flexed vs extended wrist issue for the 1HBH.

I would suggest hitting low is situational.

In golf wedge shots they may choose to hit low (bottom groove or 2) to engage a gear effect that increases spin.

This isn't a power move though its a spin move. The lower launch may compensate, to some degree, to offset the off centre hit.

Spin is important in modern tennis so it may be used fairly often particularly by male players.

In tennis like golf male players tend to choose a more spin effect to help control at the expense of power whilst the ladies use a more level contact to help access more power at the expense of spin. Bear in mind energy's conserved and so there's a trade off in where u want that energy to go.

 

[10sbeast888]

I would suggest hitting low is situational.

In golf wedge shots they may choose to hit low (bottom groove or 2) to engage a gear effect that increases spin.

This isn't a power move though its a spin move. The lower launch may compensate, to some degree, to offset the off centre hit.

Spin is important in modern tennis so it may be used fairly often particularly by male players.

In tennis like golf male players tend to choose a more spin effect to help control at the expense of power whilst the ladies use a more level contact to help access more power at the expense of spin. Bear in mind energy's conserved and so there's a trade off in where u want that energy to go.

It’s a power move in tennis as there can be micro adjustments of the face angle that adds power to the lower part. But never the upper part.

It’s also a margin of error move because if you miss low you hit short low still penetrating. If you miss high you’re out or a floater getting killed.

The golf course doesn’t kill you back.

 

[Chas Tennis]

The colored racket tilt lines in the OP can also be applied to videos with Kinovea and they stay visible as long as you choose. They can also be set to fade in & out in videos. If you single frame in some of my videos the word "IMPACT" fades in and then out with full bright "IMPACT" on the frame closest to impact. That way the frame of impact is identified and the fade in gives a warning that text is there when playing.

But anyone can simply view single frame and see the racket face tilt and how far below or above the racket center line the ball hit. This is a very important camera angle, especially for the "Projection Angle" of biomechanics (trajectory elevation). Once the ball hits, the angle of the racket face will change. The frame time in a video is always uncertain by the time between frames, so you need the proper frame recording rate in fps to make statements. We know that the ATP pros tilt the face closed on top spin drives before first touch for a reason. We don't know what the average tennis player does - I use terms like "zoo" or "unknown".

Kinovea also places two videos side-by-side for tennis stroke comparisons - the most valuable feedback that the average tennis player can afford. See tossing 'arm inversion' on pro but not forum poster.

To single frame on Vimeo, stop video, go full screen, hold down the SHIFT KEY and use the ARROW KEYS.
Some colored lines & text fade in & out added by Kinovea. Seems to skip every other frame.

Unfortunately, often for Youtube and Vimeo and especially with side-by-side videos on this forum, the video will often skip frames when you try to single frame. This happens when doing single frame when streaming on the internet and can be observed from the frame time display. A single frame advance should show a 4 or 5 millisecond increase between frames for 240 fps. If you get 8 or more milliseconds, it is skipping frames.

If you are not streaming and viewing video just on your computer, Kinovea works perfectly with no frame skipping.

Kinovea on serve.

To single frame on Youtube, stop video, go full screen, use the period & comma keys.

These videos take time to analyze and make, and often the posters of serve videos did not reply, so I stopped making them. But a great deal of information can be displayed for those interested by using Kinovea. If you spend the time, video analysis communicates a lot of information about tennis strokes. All the video information is true but can easily be misinterpreted.

But I would also prefer a simple 100 word paragraph explaining each tennis stroke than a video analysis approach .......................