Fxanimator1
Hall of Fame
Man she has a beautiful game to watch.
One Hand Backhand - Waht Force to Start Forward Swing?
- Thread starter Chas Tennis
- Start date
Shroud
Talk Tennis Guru
I suppose I can do a vid. However its hard to copy a pro. I don't think any of them have an extreme like I do. Its more extreme than Justine and well she is the most extreme that you can get high speed vid on. And no way the off hand moves the racquet down. It is just a disaster.
Will try to get one soon and maybe do some open stance. will see.
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Shroud
Talk Tennis Guru
I always catch myself looking at everything BUT the racquet and ball...
Fxanimator1
Hall of Fame
True, but take a look at how both arms and hands are set up and in position while she’s still facing forward, and then she rotates her whole torso as a unit...just like setting up for a forehand.
Chas Tennis
G.O.A.T.
See thread on The Scapula and Tennis Strokes
"Any references from outside the forum?
Do as much protraction as you can and put your arm, high, across the upper chest. The upper arm should press on the chest. Now do retraction of the scapula. There is motion of the upper arm, horizontal abduction, if the upper arm is resting on the chest as a pivot. There are other features to be seen in high speed videos, such as the downward orientation of the upper arm. During the backhand, the uppermost body also accelerates rotationally. But scapular retraction - from a position of extreme protraction - can cause shoulder horizontal abduction and may add to racket head speed. One hand backhand players show extreme protraction. If there are any publications on this subject, please post the links.
This scapular retraction + shoulder joint motion has not been confirmed and there may be safety considerations for the one hand backhand.
It is too bad that there are not more overhead camera views of the current one hand backhand players."
This video at 1:42 of Gasquet's backhand shows his scapular protraction and retraction and their timing relative to impact.
On Youtube, to single frame use the period & comma keys.
This picture shows Justine Henin's Scapular Projection.
In an instruction video, she describes this position as 'looking over your shoulder'.
"Any references from outside the forum?
Do as much protraction as you can and put your arm, high, across the upper chest. The upper arm should press on the chest. Now do retraction of the scapula. There is motion of the upper arm, horizontal abduction, if the upper arm is resting on the chest as a pivot. There are other features to be seen in high speed videos, such as the downward orientation of the upper arm. During the backhand, the uppermost body also accelerates rotationally. But scapular retraction - from a position of extreme protraction - can cause shoulder horizontal abduction and may add to racket head speed. One hand backhand players show extreme protraction. If there are any publications on this subject, please post the links.
This scapular retraction + shoulder joint motion has not been confirmed and there may be safety considerations for the one hand backhand.
It is too bad that there are not more overhead camera views of the current one hand backhand players."
This video at 1:42 of Gasquet's backhand shows his scapular protraction and retraction and their timing relative to impact.
This picture shows Justine Henin's Scapular Projection.
In an instruction video, she describes this position as 'looking over your shoulder'.
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ballmachineguy
Hall of Fame
Way too much overthinking going on here. So few moving parts on a 1hbh compared to forehand or serve. It is easy to screw up though.
Chas Tennis
G.O.A.T.
Most posts in this thread are based on high speed video observations and the video evidence was presented.
Why don't you quote one example of over thinking and make your point with high speed video observations or other evidence?
And besides, what is wrong with over thinking?
yossarian
Professional
it impedes the performance of automatic behaviors
pencilcheck
Hall of Fame
they are implying that you are going into a rabbit hole of things that are artifect of the real causes and thus you are focusing on the wrong thing.
anyway, slow mo footage is cool, having evidence is cool, but can you find things that are hidden/skewed by clothes and camera POV and framerate? There are a lot of other things that the camera cannot capture that are important to stroke production. Maybe those are most important than what you see on the outside? I believe that's what happened, and if you want as a homework assignment, see if you prove that my statement is wrong, I think that would be an interesting discussion.
I claim that one hand backhand source of motion is neither the shoulder, nor the back, and nor the arm, (which implies no ISR, *SR etc). The real source of motion are hidden/skewed by clothes, and camera angle/POV
Chas Tennis
G.O.A.T.
IowaGuy
Hall of Fame
Chas Tennis
G.O.A.T.
That is a great display of his back. You can see some things going on with the scapula and its timing. It looks as if when the rhomboids and/or trapazoids(?) shorten, the muscles between the spine and scapula bunch up. Look for full follow throughs............
I like the backhand drive at 3:01, one of the heavier paced drives. There, the scapula seems to retract back from the side of the rib cage, but not do the full follow through that shows his muscles bunched up in other backhands. The scapular motion seems timed to impact. ?
Haas has a small bend in his elbow. Does this affect use of ISR - ESR for the one hand backhand as discussed starting with geca's post.
From viewing, I'd say that Kuerten got his chin farther to the front of his shoulder, more scapular protraction. Kuerten had a hip and a shoulder injury. If anyone comes across his shoulder injury, please post.
To compare backhands in this post on Youtube, single frame and one-over-the-other, use the period & comma keys. Always select the Youtube using the Alt + Left Mouse Click, otherwise the video may start playing. Also, don't select the video by clicking near the time line.
Behind camera views at 0, 43, 1:30, 2:03. 2:58, 3:26, 4:00
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pencilcheck
Hall of Fame
Haha, there is still a part of his body that is still have clothes on, and I think the answer is right there, that's the force that starts the backhand swing, not the back. Yes, back muscle is used but it is not the force that starts the swing.
tennisbike
Professional
We each seems to be in our own universe thinking about our problems and particular area of tennis strokes. But instead of looking at all those different things, it may be useful to look at something universal and common to all tennis strokes. Go back to the fundamental, no, further back.. way way back.
If you will, join this thought exercise...
What makes something move, or rather say from rest to say having a linear constant speed motion? Force.. ok (actually net force)
For example, what makes a car go forward? It is the force from the ground. Friction force between the tire and ground, in the opposite direction of the tire motion, pointing forward makes a car go forward. The direction must be the same. Forward (net) force causes forward motion.
So how does a racket moves forward, or accelerate forward? There is a force pushing the racket forward. Where does it come from? the ground. The friction force. How do you accelerate at higher rate? greater friction force.
Now what caused friction? peaks and valleys between 2 surfaces. How to increase friction force? coefficient of friction and normal force, i.e. the force pressing the 2 surfaces together. If one is wearing the same shoes, then the greater the normal force will give one greater friction force. Other than wearing a heavy backpack, how to increase friction force? Push down harder.. for the instance. That is split step.. and pushing off the ground.
The physics is the same for anyone and anything in the world. Now .. feel the ground and use the force, for forehand, for 1 or 2 handed backhand, or for serves...
May the force be with you.
If you will, join this thought exercise...
What makes something move, or rather say from rest to say having a linear constant speed motion? Force.. ok (actually net force)
For example, what makes a car go forward? It is the force from the ground. Friction force between the tire and ground, in the opposite direction of the tire motion, pointing forward makes a car go forward. The direction must be the same. Forward (net) force causes forward motion.
So how does a racket moves forward, or accelerate forward? There is a force pushing the racket forward. Where does it come from? the ground. The friction force. How do you accelerate at higher rate? greater friction force.
Now what caused friction? peaks and valleys between 2 surfaces. How to increase friction force? coefficient of friction and normal force, i.e. the force pressing the 2 surfaces together. If one is wearing the same shoes, then the greater the normal force will give one greater friction force. Other than wearing a heavy backpack, how to increase friction force? Push down harder.. for the instance. That is split step.. and pushing off the ground.
The physics is the same for anyone and anything in the world. Now .. feel the ground and use the force, for forehand, for 1 or 2 handed backhand, or for serves...
May the force be with you.
Dragy
Legend
What if you add inertial interaction in your model? Center of mass, force vectors not passing through COM? Push 2 legs straight up each, normal to surface, and get rotation, and get arm accelerated “forward”? Etc etc etc.
Chas Tennis
G.O.A.T.
I believe that this Shapovalov backhand has all the specific video observations pointed out in this thread except that he is performing them with his feet off the ground. This thread is mostly about video observations with some thoughts on what might be going on. I did not notice anything specific about the feet to point out.
See first backhand shown. Includes more off the ground backhands.
An interesting issue is - as soon as the feet leave the ground the player is in free fall with little affects from the air. The body mass - without ground forces through the legs - might be the most reproducible platform to launch tennis strokes from. ?
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tennisbike
Professional
Well, this model is generic and does not go into the detail of the body mass distribution. But keep in mind that force may or may not pass through COM and forces are not always going vertical or horizontal. Though there are vertical and horizontal components of the forces. The vertical force pushing against the ground is what causing the ground to push up and generate friction.
tennisbike
Professional
Good point.. as always. I remember reading that article, interesting read.I believe that this Shapovalov backhand has all the specific video observations pointed out in this thread except that he is performing them with his feet off the ground. This thread is mostly about video observations with some thoughts on what might be going on. I did not notice anything specific about the feet to point out.
I would wonder where he took off and where he lands. Now he was already in motion and not at rest..
Roll back...
Based on conservation of momentum, in this case angular momentum.. let's start with say zero total angular momentum. Then when the upper torso-racket system goes counter-clockwise, the lower body leg goes clockwise. Typically we use colision equation, particularly explosion type, to solve such physics problem. Then add to this "explosion", extensions would increase the radius of moment of inertia and slows the rotation toward the end.
Highly interesting, impressive and entertaining to watch, but I will probably not imitate that in this life time.
Chas Tennis
G.O.A.T.
It seems Nishikori jumps off the ground for a lot of forehands. They are not as rare as the one hand backhands. If the legs spread, the moment of inertia of the lower body increases and then trunk and spine muscles can more effectively rotate the uppermost body........you can see shoulder to hip separation....
I'm not trying either, for now..........
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Chas Tennis
G.O.A.T.
With Robredo I'm uncertain of the 'chest press' issue and I think that he has a bend in his elbow when I think it should be straight. I had looked at Rebredo before and was uncertain then. The scapula looks as if it might be doing protraction & retraction at about the right times, but this angle is not as clear as the Hass backhand. If a curved arm meets a curved muscle at the chest it shows a shadow region where they meet. I check that but can't be sure of the contact from that shadow. An overhead camera view would show if the line between the shoulders and the upper arm move together. But now the scapular retraction has to be considered too.
I liked the wrist comments in the instruction. Forearm-to-racket shaft at about a right angle............ Again the above camera would be nice for impact angles.
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tennisbike
Professional
I found the stance interestingly connected to weight transfer vector, shoulder/torso turn/separation, and racket COM movement.
Let us model this: So we human, being bipeds, while staying balanced, our COM moves between the imaginary like between two feet. (Yes, it is more like an area, shape of a quadrilaterals, 4 sided shape.) Assume, hitting with right arm toward the right, we will stay on two feet fixed but moving forward, and not stepping forward, to simplify the model. Ball vector going left, 9 o'clock direction.
Now to hit a backhand, there are different stances. The basics are:
I get the feeling that "closed" would win, and I think I know why: (Assuming follow-through toward 3 o'clock, assuming racket take back-swing starts at pointing at 6 'clock, if feet are at 3 and 9 o'clock.)
Let us model this: So we human, being bipeds, while staying balanced, our COM moves between the imaginary like between two feet. (Yes, it is more like an area, shape of a quadrilaterals, 4 sided shape.) Assume, hitting with right arm toward the right, we will stay on two feet fixed but moving forward, and not stepping forward, to simplify the model. Ball vector going left, 9 o'clock direction.
Now to hit a backhand, there are different stances. The basics are:
- Neutral stance, i.e. parallel to ball path, weight transfer vector to the right, 3 o'clock direction. The separation is 180 degree (clockwise) between ball vector and movement vector
- semi-open, weight transfer toward about 4 or 5 o'clock direction (Separation greater than 90 but less than 180 degree counter clockwise)
- semi-close to closed, weight transfer vector toward 1 or 2 o'clock direction, separation clockwise less than 180 degree to 90 degree.
I get the feeling that "closed" would win, and I think I know why: (Assuming follow-through toward 3 o'clock, assuming racket take back-swing starts at pointing at 6 'clock, if feet are at 3 and 9 o'clock.)
- Length of the stroke - between start of stroke to contact point, if acceleration rate of racket is constant, longer distance or path travel means a greater racket speed. Neutral swings 180 degree, Open swings less than 180 degree and Closed swings greater than 180 degree. This means without swinging harder, closed stance will contact the ball at greater racket speed. But unless one is hitting backhand sitting on a fixed chair, this is kind of pointless.
- Closed enable one to naturally achieve a shoulder - back to net position, that is often mentioned for good one-handed backhand.
- Closed stance weight transfer facilitates this acceleration TOWARD the contact point, actually laterally. As the racket, was traveling or accelerating linearly, is squaring off, as in rotation/revolving, the racket head further accelerate toward contact point.
Chas Tennis
G.O.A.T.
As far as I know you can't edit thread titles.
The misspelling helps in searching for the article by Google or the forum search.
ballmachineguy
Hall of Fame
There is no such thing as the "chest press." What is happening with most modern backhands, not all (not Lopez or Federer, they do something different), is you are reaching back with as straight an arm as possible (doesn't have to be stick straight) all while resisting turning the hips (think left arm straight in golf). This builds a tremendous amount of tension in the back of the shoulder and back muscles. Initially, this reach back includes plenty of space between arm and body (watch some vids) but when the racquet drops into that "fishtail" thing (hand by left hipbone) the arm gets close to the chest. The arm looks to be against the chest on purpose, but it is the result of stretching back to build tension so when you rotate the torso into the shot you get 1:1 movement of the arm. If you had a huge gap between the arm and chest, you would start to rotate the torso and the arm wouldn't move until that gap were closed and the shot would get all messed up, like trying to pull someone on a skateboard with your car and you have a ten foot rope but they start only five feet away - nothing and then a big jerk. If you really are looking for a force that starts the forward swing, it would probably be the hips. When they try to open, that earlier resistance of not letting them close when you reached back on your unit turn, immediately starts the torso which brings the RELAXED arm through to contact. Really fly open with the torso controlling it by sticking out the off-arm like Stan. Throw it out as hard as you swing and you will be well balanced. Hit inside of ball for DTL and drives and outside of ball for cross court and big topspin. This wil cause the so-called half and full release. (Never hit a tennis ball for a particular follow through, follow throughs are the result of how you hit the ball) **Note: This is not how Federer hits his backhand, at all. Don't watch him unless you want to hit his style of backhand** Not all OHBs are the same!
pencilcheck
Hall of Fame
If it is really chest press the end result would be a backhand slice not a topspin backhand or flat backhand. (real backhand slice don't use chess press either btw) If Chas really tried shadow swing himself with a racquet and imagine the trajectory he would understand it immediately.
Chas Tennis
G.O.A.T.
Good points on the arm coming down, will read.
This thread has gotten long. Much of the evidence and videos were presented a few years ago now. I'd suggest reading post #1, #51 and then look carefully at the video evidence that has been presented. I cannot measure forces in videos. The best evidence for forces is that the upper arm moves in sync with the shoulder girdle as if there were acceleration forces keeping them pressed together. You can also do the 1 lb dumbbell demo that I described and feel the upper arm press on the chest as the uppermost body rotationally accelerates. Later than those early posts on 'chest press', a new and entirely different reason for 'chest press' appeared, Scapular Retraction. I have been recently posting on that.
In 2013, I started this thread and used the word "Start" in the title. As usual, the title of a thread doesn't limit what can be discussed or discovered in a thread. This thread is not all about what the word "Start" meant to me in 2013. It is about some interesting video observations and what I and some others think about them. If you read the thread you will see that a certain set of video observations have been associated with a group of the best one hand backhands - crisp and clear observations. The new or interesting observations were emphasized and some other things were completely left out of the discussion, foot work, etc., too pedestrian......
The phrase 'chest press' identifies certain video observations and some possible explanations. They should draw your attention to the video observations- Go to "Chest Press" St. and look at the videos.
If you want to disagree, quote the post with the video and give your interpretations for "chest press" or other point. If you think that the videos were cherry picked, present your own videos from the same player.
"There is no such thing as the "chest press."" This is a confident sounding statement but has no video evidence.
There is no proof available for forces until a biomechanical researcher places a force gauge between the upper arm and chest and measures force directly. I looked for a WiFi sensor but did not find a low cost option. Does anyone know about small force plates with battery power? Baseball batters use the same 'chest press' technique, maybe baseball has conducted force plate measurements between the chest and upper arm? For safety, the friction on the forces plate should not be much different than for the chest and upper arm.
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pencilcheck
Hall of Fame
Well, I think for me the evidence is that I can execute OHBH without doing chest press, thus eliminating the argument that it could exist anywhere in the phase of stroke production therefore not in the starting force. Video evidence is hard to tell muscle movement and intention so sometimes you need other types of evidence to help you with your argument. Otherwise if you only have a hammer you see everything/every problem as a nail. I think you are falling into that trap.
tennisbike
Professional
As each of us are searching for slightly different things. For me, I am more targeting something universal, some element that exists in all strokes, all motion.. in this thread, one-handed backhand for all players. If two players can produce the same ohbh but one uses bend elbow and the other straight, then that, elbow bend/straight is not universal, not essential to produce sound ohbh. On the same token, chess-press is sometimes observed and not all the time, that for me infers that chess-press is not universal or essential. Would the idea of chess-press make you hit a better ohbh? Maybe, or maybe not. There are plenty of tennis tips and instructions that are just that, images or directions that may or may not match reality, but meant to help players find their strokes.
Sorry I feel that I am bursting your bubble.
Anyway, I think ohbh is fascinating because I feel like when you get the motion just right, good timing, smooth and not forced, it is a beautiful shot. There are elements that I thought helps.. close stance, unit turn/torso separation, movement/weight transfer toward the side, leading with shoulder, cocking the wrist/racket (abduction) .. The issue is then how to connect all those elements and firing them in the right manner/sequence. Then grooving it.. I can dream, of course.
Sorry I feel that I am bursting your bubble.
Anyway, I think ohbh is fascinating because I feel like when you get the motion just right, good timing, smooth and not forced, it is a beautiful shot. There are elements that I thought helps.. close stance, unit turn/torso separation, movement/weight transfer toward the side, leading with shoulder, cocking the wrist/racket (abduction) .. The issue is then how to connect all those elements and firing them in the right manner/sequence. Then grooving it.. I can dream, of course.
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1stVolley
Professional
It looks like the OP needs to backtrack and get back to a few fundamentals. He'd need a Ph.D to get through all the analysis thrown at him. And trying to emulate what the elite pros are doing when you are trying to fundamentally establish a solid stroke is risky business.
Assuming you are using the proper Eastern backhand grip and have some degree of a looped backswing, you need to insure (1) a closed stance which is completed just before the forward swing; (2) whenever possible you should include an aggressive step forward with the leading foot in that closed stance; (3) keeping your non-dominant hand on the racquet throat until the racquet head is in the "slot" position, i.e. just before the forward swing begins; (4) strongly push the non-dominant arm in the opposite direction from the forward swing as the latter develops; (5) incorporate in the forward swing a "forearm roll" which gives a bit of windshield wiper motion to the racquet head.
Suggestion #2 will automatically lower your torso and help shape your stroke, adding some needed topspin. Suggestion #3 helps insure the racquet drops into the slot position. Suggestion #4 prevents opening the torso too soon by counterbalancing the force of the forward swing as well as helping accelerate this swing. Suggestion (5) helps with topspin and, importantly, helps prevent too rigid "arming" of the stroke due to gripping the racquet too tightly and tensing the wrist too much.
When practicing, pick only one suggestion at a time and work until it become automatic before going on to other suggestions. I would start with suggestion #1 first, then go to the other suggestions in the order you see fit. It is beneficial when starting on any of the suggestions to do so by dropping the ball for yourself until you get the technique mostly under control before working with a partner, ball machine or wall.
As far as effort required in the forward swing: when establishing these fundamentals simply swing easily, without undue strain. As you time the contact with the ball more accurately, your pace will increase with the same effort. And as you insure that your non-dominant arm quickly moves in the opposite direction as your forward swing, extra power will be injected into your stroke.
Assuming you are using the proper Eastern backhand grip and have some degree of a looped backswing, you need to insure (1) a closed stance which is completed just before the forward swing; (2) whenever possible you should include an aggressive step forward with the leading foot in that closed stance; (3) keeping your non-dominant hand on the racquet throat until the racquet head is in the "slot" position, i.e. just before the forward swing begins; (4) strongly push the non-dominant arm in the opposite direction from the forward swing as the latter develops; (5) incorporate in the forward swing a "forearm roll" which gives a bit of windshield wiper motion to the racquet head.
Suggestion #2 will automatically lower your torso and help shape your stroke, adding some needed topspin. Suggestion #3 helps insure the racquet drops into the slot position. Suggestion #4 prevents opening the torso too soon by counterbalancing the force of the forward swing as well as helping accelerate this swing. Suggestion (5) helps with topspin and, importantly, helps prevent too rigid "arming" of the stroke due to gripping the racquet too tightly and tensing the wrist too much.
When practicing, pick only one suggestion at a time and work until it become automatic before going on to other suggestions. I would start with suggestion #1 first, then go to the other suggestions in the order you see fit. It is beneficial when starting on any of the suggestions to do so by dropping the ball for yourself until you get the technique mostly under control before working with a partner, ball machine or wall.
As far as effort required in the forward swing: when establishing these fundamentals simply swing easily, without undue strain. As you time the contact with the ball more accurately, your pace will increase with the same effort. And as you insure that your non-dominant arm quickly moves in the opposite direction as your forward swing, extra power will be injected into your stroke.
tennis tom
Legend
Chas Tennis
G.O.A.T.
Scapular Protraction and Scapular Retraction
Because of the unusual shoulder use seen in some top one hand backhand players, the possible biomechanics were speculated above.
Here is Kuerten with extreme scapular protraction ready to start the scapular retraction for the forward swing. See videos for the timing of these scapular motions relative to the forward swing. The scapula has the glenoid half of the shoulder joint and the upper arm bone moves around with the scapula.
For reference, here is a discussion of the structure and function of the scapula. The article discusses the importance of the scapular motions for the shoulder and avoiding shoulder injuries. Exercises and stretches that tune scapular muscles are important for conditioning and injury prevention.
The Role of the Scapula in the Rehabilitation of Shoulder Injuries Michael L. Voight, DPT, OCS, SCS, ATC; Brian C. Thomson, SPT
Note: Kuerten had a shoulder injury and hip injury around the time of his best years. I have been looking for details on that shoulder injury. If anyone has some information, please post.
Kuerten slow motion one-hand backhand at 32 sec.
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AndreDaGamer
Rookie
it's not a 1hbh tutorial but they noted a few points i hadn't thought of before. interesting material for yall 1hbh and 1hbh-curious players out there
socallefty
G.O.A.T.
Nice video. Which backhand do you guys like the best and want to use as a model? I vote for Thiem - a thing of beauty and yet breathtaking power.
Chas Tennis
G.O.A.T.
Good video for observing Federer backhand.
Look at the area between the chest and upper arm to see when they separate. This earlier use of the shoulder joint differs between Federer's technique and several other top backhands such as those of Wawrinka, Justine Henin and Gasquet.
To compare videos single frame on Youtube use the period & comma keys. Always, use the alt key + left mouse click together, otherwise the video starts playing. You can go to full screen and back down and the video stays on the same frame. To compare find impacts and go back and forth single frame to cover the backhand stroke. For most accurate comparisons use the same camera viewing angles.
Look at the area between the chest and upper arm to see when they separate. This earlier use of the shoulder joint differs between Federer's technique and several other top backhands such as those of Wawrinka, Justine Henin and Gasquet.
To compare videos single frame on Youtube use the period & comma keys. Always, use the alt key + left mouse click together, otherwise the video starts playing. You can go to full screen and back down and the video stays on the same frame. To compare find impacts and go back and forth single frame to cover the backhand stroke. For most accurate comparisons use the same camera viewing angles.
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SystemicAnomaly
Bionic Poster
One Hand Backhand - Waht Force to Start Forward Swing?
From physics classes, I learned about a number of different forces: EM, Gravitational, Strong, and Weak forces. Apparently, I should now investigate & learn about this new Waht force.
Best resources for this? Is this related to string theory, QM or a new theory of everything?
From physics classes, I learned about a number of different forces: EM, Gravitational, Strong, and Weak forces. Apparently, I should now investigate & learn about this new Waht force.
Best resources for this? Is this related to string theory, QM or a new theory of everything?
Chas Tennis
G.O.A.T.
Once you post a thread title, you cannot edit the title.
Everyone should be interested in the microscopic sources of force from muscles. The body has sarcomeres, where the size is a few microns so that the smaller details have to be examined with an electron microscope. The sarcomeres have Actin & Myosin structures, that nerve cells activate, to form "cross bridges" and produce forces to shorten the muscle. They produce "active" forces, a term used in the Hill Muscle Model. Sarcomeres also have Titin, the largest molecule in the human body. Titin is a hot research topic, thought to kink the giant molecule to shorten and produce forces. (Old text books that refer to tendons stretching for elastic forces are outdated.) The 'active forces' from Actin & Myosin and 'passive forces' from Titin have limitations of shortening speed and force vs length that determine effective tennis stroke techniques including the backhand. Titin is fastest.
On the smallest force scales of atoms and electrons, etc. , I believe that the EM forces make the Actin, Myosin, and Titin work.
In other words, your muscle sarcomeres have Myosin walking, running and standing fast on Actin pathways and Titin rubber bands. These sources of sarcomere forces are at the heart of your tennis strokes. Google - Myosin Actin Titin pictures
Everyone should be interested in the microscopic sources of force from muscles. The body has sarcomeres, where the size is a few microns so that the smaller details have to be examined with an electron microscope. The sarcomeres have Actin & Myosin structures, that nerve cells activate, to form "cross bridges" and produce forces to shorten the muscle. They produce "active" forces, a term used in the Hill Muscle Model. Sarcomeres also have Titin, the largest molecule in the human body. Titin is a hot research topic, thought to kink the giant molecule to shorten and produce forces. (Old text books that refer to tendons stretching for elastic forces are outdated.) The 'active forces' from Actin & Myosin and 'passive forces' from Titin have limitations of shortening speed and force vs length that determine effective tennis stroke techniques including the backhand. Titin is fastest.
On the smallest force scales of atoms and electrons, etc. , I believe that the EM forces make the Actin, Myosin, and Titin work.
In other words, your muscle sarcomeres have Myosin walking, running and standing fast on Actin pathways and Titin rubber bands. These sources of sarcomere forces are at the heart of your tennis strokes. Google - Myosin Actin Titin pictures
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SystemicAnomaly
Bionic Poster
Well aware. Just giving you a hard time about the typo... making a dumb joke at your expense. No harm. No foul.
Chas Tennis
G.O.A.T.
This is an especially good video for analysis of the one hand backhand.
Video showing a point and Justine Henin backhands ending with the "blistering backhand" with a very informative camera angle, slow motion, at 44 seconds.
Compare backhand details below on this post, single frame and one above the other. To single frame on Youtube use the period & comma keys. Always us the alt key + left mouse click, otherwise the video starts playing. Select frames to show sub-motions at different times, such as how the hips and shoulders turn from start to impact.
Second 44. Compare positions and angles at 2 or 3 different times. Recommend starting all 3 videos at impact frame.
Compare selected frames to see sub-motions and how they are timed and relate to one another:
1) the range of motion of the line between the two shoulders,
2) shoulder rotation angle, start to impact,
3) range of the hip rotation, observe the line between the two hips
4) head tracking accuracy viewing ball at 3 positions,
5) angle of the racket shaft up or down vs time as an indication of external shoulder rotation of the hitting arm,
6) observe when the left foot pushes and then leave the ground and the line between the two hips at those times and how the line between the hips rotates afterward,
7) wrist angle before impact
8) others, etc.
The most interesting question for me is, what are the forces turning the line between her two hips? What part do the feet play and what part do abdominal, spine, hip and other muscles play?
Video showing a point and Justine Henin backhands ending with the "blistering backhand" with a very informative camera angle, slow motion, at 44 seconds.
Compare backhand details below on this post, single frame and one above the other. To single frame on Youtube use the period & comma keys. Always us the alt key + left mouse click, otherwise the video starts playing. Select frames to show sub-motions at different times, such as how the hips and shoulders turn from start to impact.
Second 44. Compare positions and angles at 2 or 3 different times. Recommend starting all 3 videos at impact frame.
Compare selected frames to see sub-motions and how they are timed and relate to one another:
1) the range of motion of the line between the two shoulders,
2) shoulder rotation angle, start to impact,
3) range of the hip rotation, observe the line between the two hips
4) head tracking accuracy viewing ball at 3 positions,
5) angle of the racket shaft up or down vs time as an indication of external shoulder rotation of the hitting arm,
6) observe when the left foot pushes and then leave the ground and the line between the two hips at those times and how the line between the hips rotates afterward,
7) wrist angle before impact
8) others, etc.
The most interesting question for me is, what are the forces turning the line between her two hips? What part do the feet play and what part do abdominal, spine, hip and other muscles play?
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Chas Tennis
G.O.A.T.
Comparison of Gasquet backhand at 12 in 1999 to Gasquet at a 2017 Australian Open practice.
Compare videos in this post, single frame and one above the other. To single frame on Youtube use the period & comma keys. Always select the YT video using the alt key + left mouse click, otherwise the video starts playing. Go to impacts of each backhand and work back and forth single frame. Select the most similar camera angles for most accurate comparisons.
Video starts at 1:20 with Gasquet on close side of the court. The 2017 video indicates 4000 fps.
"Gasquet is on the close side of the net for backhands only at
1:26
1:42
1:58
2:04
1) Similar to now, his racket was held high on take back.
2) Similar to now, straight arm for forward swing.
3) Have yet to compare uppermost body turn angles. ?
4) Racket & arm rotated down. Needs comparison. ?
--------------
5) Chest press hard to see due to video quality. ?
6) Scapular Protraction ? not visible due to camera angle. ?
There are similarities to Gasquet's backhand now and some things that are not clear in that video. It looks as if he might have had much of his backhand by age 12. ?
He sometimes runs around his backhand to hit a forehand.
Gasquet apparently was already famous at 9 so I hope we eventually see earlier videos. "
Compare videos in this post, single frame and one above the other. To single frame on Youtube use the period & comma keys. Always select the YT video using the alt key + left mouse click, otherwise the video starts playing. Go to impacts of each backhand and work back and forth single frame. Select the most similar camera angles for most accurate comparisons.
Video starts at 1:20 with Gasquet on close side of the court. The 2017 video indicates 4000 fps.
"Gasquet is on the close side of the net for backhands only at
1:26
1:42
1:58
2:04
1) Similar to now, his racket was held high on take back.
2) Similar to now, straight arm for forward swing.
3) Have yet to compare uppermost body turn angles. ?
4) Racket & arm rotated down. Needs comparison. ?
--------------
5) Chest press hard to see due to video quality. ?
6) Scapular Protraction ? not visible due to camera angle. ?
There are similarities to Gasquet's backhand now and some things that are not clear in that video. It looks as if he might have had much of his backhand by age 12. ?
He sometimes runs around his backhand to hit a forehand.
Gasquet apparently was already famous at 9 so I hope we eventually see earlier videos. "
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Raul_SJ
G.O.A.T.
This instruction says that the RH tip must be well above the grip like Stan and not like the common rec player position in first pic. The claim is that it creates more space to accelerate and better leverage. But the Mac backhand has the same pic#1 position.
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Raul_SJ
G.O.A.T.
Meaning which frame#?
Also, it appears that the unit turn ends at frame #3. For a slow incoming ball, frame #3 is where one would pause before initiating the backswing. Do you agree?
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Chas Tennis
G.O.A.T.
Meaning which frame#?
Also, it appears that the unit turn ends at frame #3. For a slow incoming ball, frame #3 is where one would pause before initiating the backswing. Do you agree?
Between #4 & #5 is the downward motion of the racket head that I referred to. Her uppermost body does not appear to have moved forward very much. The downward motion then also is part of adjusting for ball height.
I don't recall saying anything about "pauses". If I wanted to say anything about the timing of pauses, I would study high speed videos of backhands of each technique and the variety in use. If you are interested in pauses study some match videos. Maybe players minimize the pause and keep moving if they can, an interesting question.
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Chas Tennis
G.O.A.T.
This instruction says that the RH tip must be well above the grip like Stan and not like the common rec player position in first pic. The claim is that it creates more space to accelerate and better leverage. But the Mac backhand has the same pic#1 position.
[/QUOTE]
There is not enough information to understand the comment "this is creating no space to accelerate the racket and no leverage".
It would be much easier to follow the following word description if you are watching a high speed video of the racket being brought down frame-by-frame.
Justine Henin's backhand illustrates all points discussed. When she has lowered the racket you can see that her hitting arm is higher than it would have been had the racket shaft not been rotated down. Observe the horizontal angle of the racket shaft.
This video starts at 44 seconds for that one backhand. Single frame with the period & comma keys.
I believe that the racket is initially held high to position the hand high because the biomechanics benefits from the upper arm and arm being at a more elevated angle. That way when the uppermost body turns the racket head is farther away from the rotation axis (through neck area) and the racket head speed is higher. I have discussed this at places in this thread and illustrated it in detail with the Mojo28 vs Gasquet comparison in post #106. Your pictures illustrate that Wawrinka's upper arm is at an elevated angle, hand high, to begin the racket bring down. Compare to instructor's upper arm angle. Since the racket and arm are rotated down with internal shoulder rotation that allows the upper arm to remain higher. If the upper arm tilts down - to do all the height adjustment without ISR - the racket head gets closer to the rotation axis (neck area). That reduces racket head speed.
Justine Henin, Wawrinka and Gasquet & others mentioned are my models for the one hand backhand technique that I prefer. I prefer it because it is more widely used by top ATP players with 1HBHs and I have felt the chest press at the upper arm and other reasons.
Note- in physics 'good leverage' increases the applied force (and decreases the speed of movement). Apply 10 pounds and get 50 pounds at the other end of the lever. Google: lever
In tennis usage 'leverage' or 'good leverage' gives you anything that you want for the tennis stroke. Good leverage in tennis is usually for more speed and less force, the opposite of physics. The muscles of the body increase the speed of movement between the muscle attachment and the application, say, at the hand. Apply 50 lbs at the muscle's attachment and get 10 lbs at the hand, but the hand moves 5X faster than the attachment.
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tennisbike
Professional
Perhaps someone can "observe" force, or specifically net force. From a physics point of view, it is the net force, i.e. the combined force, acting on an object to cause the motion to change, to accelerate or change velocity. And there are contact forces that you can see or non-contact forces out there. And just because 2 objects are in contact there may be a normal force acting on it, or not. And there is no way to show or to measure how great or how little the normal force is, unless a load cell is placed between the two bodies. Thus I conclude that there MAY be some normal force between the chest and the arm.
Now on a completely different angle, that is outside of my original learning of physics, the current understanding of our world is based on the 4 fundamental forces of our universe: (from strong to weak) Strong nuclear forces, electromagnetic forces, weak nuclear forces, and gravity. Based on this standard model, the normal forces are the result of electromagnetic forces. Strong and weak nuclear forces acts at a very small distance, like between protons. And gravitational force is the weakest force. Thus one can claim that electromagnetic forces is the source of xx, such as a ohbh. Yeah, everything is full of holes and nothing is solid, wow!
Lately, I have been enjoying playing with the Dunlop Max 200G and the mass does not bother me so much on the forehand. I wonder if I had figured out the timing on fh, since in a pendulum the timing is related to the length and gravity and not mass. But backhand needed more tweaking. Thus the goal is to use the gravitational force more efficiently thus the timing would be the less dependent on the swing speed, i.e. take back. I was taught to swing/take back quicker when facing faster balls, so I have to unlearn that. Ultimately it is more important to focus on timing than force for me.
Fxanimator1
Hall of Fame
Between #4 & #5 is the downward motion of the racket head that I referred to. Her uppermost body does not appear to have moved forward very much. The downward motion then also is part of adjusting for ball height.
I don't recall saying anything about "pauses". If I wanted to say anything about the timing of pauses, I would study high speed videos of backhands of each technique and the variety in use. If you are interested in pauses study some match videos. Maybe players minimize the pause and keep moving if they can, an interesting question.
An interesting thing to notice in Henin's BH, is that she uses a more "pendulum" style takeback rather than a "C" shaped takeback.
tennis tom
Legend
YES!
Raul_SJ
G.O.A.T.
On the typical forehand in the ATP, there is a point where the player pauses or extremely slows down the racquet; that is the nature of tennis -- there will often be slow incoming balls on which you must "wait". Essentially pause before beginning the acceleration and continuous motion.
We see that point here in the below forehand pics. Fed is about to release the racquet with the left hand, drops the racquet, employs loop drop gravity assist, in one continuous motion... Notes:
Fed not use a pure "C" loop like Delpo, but the gravity assist concept is similar.
There has been some discussion here on the left hand possibly assisting the backhand drop?
In any case, there must be a "pause" analogue on the Henin backhand and 1hbh in general. Probably Frame #3 or #4.
Discuss!
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