Sock/Kyrgios forehand

#1
As mentioned in the youtube video below it would appear that Jack Sock's seemingly elaborate backswing results in more racquet head speed and ball rotation than almost any forehand on the tour. The video outlines the fact that Sock's hand actually travels in a very similar path to that of more old school style players such as Federer. However the tip of the racquet follows a significantly different path. To me this indicates that Sock is reorienting his wrist at various stages of the swing and this is resulting in the tip of the racquet moving in a different path and ultimately faster!?

I was wondering if anyone could shed some light on the biomechanical principles underpinning the Jacky Sock forehand, that seems to be tangential to Nicky Kyrgios's forehand. Or even just comment on whether you think their forehands are good or not...

(Jack Sock ultimate lag forehand)

(Jack Sock's forehand stifled by Dimitrov)

(Nick Kyrgios forehand slow motion)

(Nick Kyrgios fastest shots)
 
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#2
It seems to be a recurring theme on the take back of the serve for some of the bigger servers/younger players as well, where the racquet head doesn't end up behind the elbow until just before initiating the forward swing;

(Sam Groth serve slow mo)

(Nick Kyrgios serve slow mo)

(Jack Sock serve slow mo)

I was always taught to chop my toes off in the traditional action, in which case the racquet head is behind the elbow much earlier in the swing. It seems leading with the elbow in the take back (and laying the racquet head back at the last minute) is a way to generate more racquet head speed! Comments please!?…..
 
#3
If you say the racket head is 'behind the elbow', what do you mean? Farther back in the court? Or, farther back behind the server's back? Court reference or player's body reference?

When you describe stroke positions with words there is often ambiguity.

Just giving us videos from various camera angles and not identifying the exact frame or time that you have in mind, makes it very difficult to identify what you are describing. If you show high speed video frames - from very, very close camera viewing angles, say, to the ball's final trajectory, that is probably the most comparable that we can get. References in the videos are very useful, say the ball's trajectory as it moves away, or some court lines, or a court pole that can be used as a vertical reference, etc.

I noticed surprising angular positions for external shoulder rotation when the legs first thrust up in high level serves. Also, Trophy Position is a very different thing for one group of high level servers regarding the ESR rotation rate at TP. Some are moving at TP, Raonic, Sampras and some are not, Sharapova and Wawrinka, etc.

Often the angles we are interested in might be 15 or 20 degrees. To see angles of 15 or 20 degrees in a tennis stroke the camera viewing angles have to be near identical. No ad and deuce court comparisons unless the camera is viewing the ball's trajectories from the same angle in the ad and deuce courts.

If only 20 d, does the player's flexibility figure into that 20 degrees? For example, what is the maximum ESR that a server reaches in the serve? Because we are interested in the stretch of muscles, angles relate to the spine and not to the court. Even the bend of the spine, Thoracic Extension, figures in for the amount of stretch.

Also, for comparisons the type of serve, flat, slice or kick, has to be identified.

Kinovea is a free video analysis program that allows stop action, side-by-side video comparisons and instant saving "Key Images" as you view the videos. It is easy and fun to use. You can add angles that measure & display the video angle. Many other features.

Kinovea has 8.15 an older version and Kinovea 8.25 a new version with more features.
 
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#4
Biomechanically speaking, it's rather simple really. It all has to do with your shoulder position. Most pros go from neutral-ESR-ISR to generate the whip. Jack goes from ISR-ESR-ISR. In other words, he generates more RHS because he starts off with the shoulder fully internally rotated.

If you watch the slow mo, Jack goes to full ISR before the forward swing. His elbow is higher than his hand.
 
#5
Jack Sock has a bent elbow forehand.

Federer has a straight arm forehand. Comparing the two and showing complicated hand paths for Sock, I found hard to follow. Besides the hand loops are always a 2D version of 3D space. The dimension toward or away from the camera is not shown well.

This thread has some discussions.
https://tt.tennis-warehouse.com/ind...lerate-through-the-ball.573939/#post-10700495

To me the Jack Sock forehand looks stressful for the elbow. ??
 
#6
Biomechanically speaking, it's rather simple really. It all has to do with your shoulder position. Most pros go from neutral-ESR-ISR to generate the whip. Jack goes from ISR-ESR-ISR. In other words, he generates more RHS because he starts off with the shoulder fully internally rotated.

If you watch the slow mo, Jack goes to full ISR before the forward swing. His elbow is higher than his hand.
good explanation.
 
#7
The video outlines the fact that Sock's hand actually travels in a very similar path to that of more old school style players such as Federer.
Is that what it did? By that logic, any hack 2.0 forehand has a very similar hand path to Federer's. It was significantly loopier and the hand basically stayed in the same place on the backswing. It traveled in a tiny circle then went into a large loop. Federer's went in a medium loop in the backswing then went into a near linear path into the ball. If that's similar, then hey, a newbie's straight back straight forward swing is similar too!
 
#8
Is that what it did? By that logic, any hack 2.0 forehand has a very similar hand path to Federer's. It was significantly loopier and the hand basically stayed in the same place on the backswing. It traveled in a tiny circle then went into a large loop. Federer's went in a medium loop in the backswing then went into a near linear path into the ball. If that's similar, then hey, a newbie's straight back straight forward swing is similar too!
It was certainly more similar than the path of the tip of the racquet!
 
#9
If you say the racket head is 'behind the elbow', what do you mean? Farther back in the court? Or, farther back behind the server's back? Court reference or player's body reference?

When you describe stroke positions with words there is often ambiguity.

Just giving us videos from various camera angles and not identifying the exact frame or time that you have in mind, makes it very difficult to identify what you are describing. If you show high speed video frames - from very, very close camera viewing angles, say, to the ball's final trajectory, that is probably the most comparable that we can get. References in the videos are very useful, say the ball's trajectory as it moves away, or some court lines, or a court pole that can be used as a vertical reference, etc.

I noticed surprising angular positions for external shoulder rotation when the legs first thrust up in high level serves. Also, Trophy Position is a very different thing for one group of high level servers regarding the ESR rotation rate at TP. Some are moving at TP, Raonic, Sampras and some are not, Sharapova and Wawrinka, etc.

Often the angles we are interested in might be 15 or 20 degrees. To see angles of 15 or 20 degrees in a tennis stroke the camera viewing angles have to be near identical. No ad and deuce court comparisons unless the camera is viewing the ball's trajectories from the same angle in the ad and deuce courts.

If only 20 d, does the player's flexibility figure into that 20 degrees? For example, what is the maximum ESR that a server reaches in the serve? Because we are interested in the stretch of muscles, angles relate to the spine and not to the court. Even the bend of the spine, Thoracic Extension, figures in for the amount of stretch.

Also, for comparisons the type of serve, flat, slice or kick, has to be identified.

Kinovea is a free video analysis program that allows stop action, side-by-side video comparisons and instant saving "Key Images" as you view the videos. It is easy and fun to use. You can add angles that measure & display the video angle. Many other features.

Kinovea has 8.15 an older version and Kinovea 8.25 a new version with more features.
I mean the players hitting arm elbow relative to the racquet relative to the direction that the player is hitting the serve. (In front being closer to the direction the serve is intended to go and behind being further from it). I'll have to have a look at Kinovea!
 
#10
Biomechanically speaking, it's rather simple really. It all has to do with your shoulder position. Most pros go from neutral-ESR-ISR to generate the whip. Jack goes from ISR-ESR-ISR. In other words, he generates more RHS because he starts off with the shoulder fully internally rotated.

If you watch the slow mo, Jack goes to full ISR before the forward swing. His elbow is higher than his hand.
Yes, this confirms what I suspected, he is coiling the arm at the shoulder into maximal internal rotation during the backswing. I'm not 100% clear on how this translates to racquet head speed, but I have some idea.
 
#11
Jack Sock has a bent elbow forehand.

Federer has a straight arm forehand. Comparing the two and showing complicated hand paths for Sock, I found hard to follow. Besides the hand loops are always a 2D version of 3D space. The dimension toward or away from the camera is not shown well.

This thread has some discussions.
https://tt.tennis-warehouse.com/ind...lerate-through-the-ball.573939/#post-10700495

To me the Jack Sock forehand looks stressful for the elbow. ??
Yes, I agree it was quite difficult to follow. Good point regarding 2D representation of 3D. I'll have a look at that thread, I figured there would be one. I have found this technique seems to be stressful on the shoulder actually.
 
#13
Jack certainly generates a lot of RHS. However, that's not that hard to do. Plenty of guys can swing fast. The trick, however, is making clean contact with ball on stringbed at very high RHS. Jack sometimes struggles with this on his forehand, and almost always struggles with this on his backhand. Nick Kyrigos may have slightly less RHS but almost always strikes it cleanly on both sides.
 
#14
It seems to be a recurring theme on the take back of the serve for some of the bigger servers/younger players as well, where the racquet head doesn't end up behind the elbow until just before initiating the forward swing;

(Sam Groth serve slow mo)

(Nick Kyrgios serve slow mo)

(Jack Sock serve slow mo)

I was always taught to chop my toes off in the traditional action, in which case the racquet head is behind the elbow much earlier in the swing. It seems leading with the elbow in the take back (and laying the racquet head back at the last minute) is a way to generate more racquet head speed! Comments please!?…..
Leading with the elbow on the take back isn't anything new. Bjorn Borg, Vilas, Sampras, Agassi, and most other good FHs did it decades ago. It helps keep the prep short, allowing for a compact take back. It also helps close the racket face a bit on the prep and take back which is good for hitting topspin. Vic Braden was coaching "lead the backswing with the elbow in the 1970s (and maybe sooner). But, you are correct it is almost universal in the modern game. I also agree the racket head doesn't fall behind elbow until you start the forward swing. This is also good technique and helps keep a nice compact swing.
 
#16
I think some of this can be explained by Sock's grip, he uses full western and if you've tried hitting like this you'll find it lends to a somewhat more active wrist during the swing.
Wow, you can read my mind!!! I literally just opened this thread to ask that very question (what grip does Sock use) and there was the answer!
 
#17
Leading with the elbow on the take back isn't anything new. Bjorn Borg, Vilas, Sampras, Agassi, and most other good FHs did it decades ago. It helps keep the prep short, allowing for a compact take back. It also helps close the racket face a bit on the prep and take back which is good for hitting topspin. Vic Braden was coaching "lead the backswing with the elbow in the 1970s (and maybe sooner). But, you are correct it is almost universal in the modern game. I also agree the racket head doesn't fall behind elbow until you start the forward swing. This is also good technique and helps keep a nice compact swing.
Yeah you're right certainly Sampras and Agassi (I haven't seen much of Borg or Villas) lead with the elbow in the take back. They don't internally rotate (at the shoulder and forearm) on the way back as much as Jacky Sock does of course.

I was always told to get your elbow forward to get the racquet back quickly, to me it looks like the Sock/Kyrgios lead with the elbow technique would result in being late. In practice though this doesn't seem to be the case. I guess leading with the elbow provides the momentum to get the racquet back quickly, followed by a much quicker elastic recoil at the back of the backswing which results in more racquet head speed in the forward swing. I'm still not 100% sure how the internal rotation translates into racquet head speed, which it obviously does or they wouldn't do it!?

Also, what do you make of Phillipoussis's backswing? It seems to be a bit similar to Sock and Kyrgios's forehand.


 
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#19
I guess leading with the elbow provides the momentum to get the racquet back quickly, followed by a much quicker elastic recoil at the back of the backswing which results in more racquet head speed in the forward swing.
When you "unit turn," what you're really turning as a "unit" are your torso and your upper arms. This prevents you from taking the racquet back at the shoulder, which encourages arm swinging, but also sets your hitting arm where it's going to need to be as you launch into the forward part of your stroke -- specifically, with the upper arm up and out away from the body.

A unit turn used to look like this for a classic, eastern, bent-elbow forehand.



Get the racquet back where it needs to be, then swing forward, low to high, and drive the ball. Elbow remains bent the whole way, because it's going to be bent at contact. But nothing radical looking about the swing. Easy peasy.

But tennis players discovered that the snapback effect from external rotation could provide more racquet head speed (RHS) at contact with less effort, so they started employing those loops. Borg (different grip, so we'll skip him for now), Lendl, Sampras eventually. Take the racquet back high, let gravity drop it down as the forward swing begins, externally rotating the arm, and snap it forward with the forward swing. More power, more spin, no additional effort. Genius. Again, their unit turn sets the upper arm where it needs to be for the stroke, but the elbow still goes to the position it'll be in for the hit: bent.



It's not so much about "leading with the elbow," as about putting the upper arm and elbow in the positions from which they need to drop in order to come forward in a proper, bent-arm hitting structure. Do that, and the elbow is going to lead.

Now, this served its purpose, but it has an interesting secondary effect: when the elbow is the furthest thing back, gravity acts upon it the most. The ELBOW becomes the primary thing that drops, and the whole stroke rotates around the elbow to an extent. This effect was still fairly modest with Lendl and Pete, but has been harnessed even further today.

You can see this in the modern game, where guys like Sock and Kyrgios continue to make contact with very bent elbow hitting structures. During the turn, they set the upper arm where it needs to be in order to rotate forward into the shot with the body, at a height where it'll drop to produce ESR, with an angle that assures that bent elbow at contact.



When they initiate their drops, they really accentuate the drop of the elbow as the focal point. It drops into the slot, forcing the whole forearm to rotate around it, first externally, then internally.

In fact, take a look at the Sock video that image was pulled from. Really take time to notice the degree to which the stroke is built around the position of that elbow. It leads the stroke back, drops first, and becomes the fulcrum for the whole stroke. Once you notice that, the leading elbow ought to become pretty simple to understand.


  • Unit turn with arm out, elbow bent and high up
  • Elbow drops and body/upper arm "unit" begins to rotate forward, pushing elbow ahead of racquet, creating lag
  • Forearm rotates around upper arm

This differs, incidentally, from the turn you'll see from Del Potro, or Federer, or Nadal. They don't want the racquet arm to drop such that the elbow becomes the focus of rotation. They want the racquet back further, and the elbow straighter, so that when THEY drop from their loop and begin to swing forward, the RACQUET is the primary counterweight (instead of the elbow), which pulls the arm straight. Their ESR/ISR happens around a different axis, rotating the whole arm around the shoulder, rather than rotating the forearm around the upper arm at an angle. So their takebacks lead less (or in Del Potro's case, not at all) with the elbow, and more with the racquet. The upper arm still has to find its slot, but the takeback becomes more about getting the racquet set as a counterweight.

So for straight arms...

  • Unit turn with arm out, racquet leads back high, elbow fairly straight
  • Racquet drops, body/upper arm "unit" begins to turn, weight of racquet pulls arm straight, creating lag
  • Forearm rotates with upper arm, racquet rotates around wrist

TL;DR -- the takeback is about (among other things) putting the part you want to drop first the furthest back, so that your swing's rotation will build around that. For bent-arm hitters, that'll be the elbow. For straight arm hitters, that'll be the racquet.
 
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#21
When you "unit turn," what you're really turning as a "unit" are your torso and your upper arms. This prevents you from taking the racquet back at the shoulder, which encourages arm swinging, but also sets your hitting arm where it's going to need to be as you launch into the forward part of your stroke -- specifically, with the upper arm up and out away from the body.

A unit turn used to look like this for a classic, eastern, bent-elbow forehand.



Get the racquet back where it needs to be, then swing forward, low to high, and drive the ball. Elbow remains bent the whole way, because it's going to be bent at contact. But nothing radical looking about the swing. Easy peasy.

But tennis players discovered that the snapback effect from external rotation could provide more racquet head speed (RHS) at contact with less effort, so they started employing those loops. Borg (different grip, so we'll skip him for now), Lendl, Sampras eventually. Take the racquet back high, let gravity drop it down as the forward swing begins, externally rotating the arm, and snap it forward with the forward swing. More power, more spin, no additional effort. Genius. Again, their unit turn sets the upper arm where it needs to be for the stroke, but the elbow still goes to the position it'll be in for the hit: bent.



It's not so much about "leading with the elbow," as about putting the upper arm and elbow in the positions from which they need to drop in order to come forward in a proper, bent-arm hitting structure. Do that, and the elbow is going to lead.

Now, this served its purpose, but it has an interesting secondary effect: when the elbow is the furthest thing back, gravity acts upon it the most. The ELBOW becomes the primary thing that drops, and the whole stroke rotates around the elbow to an extent. This effect was still fairly modest with Lendl and Pete, but has been harnessed even further today.

You can see this in the modern game, where guys like Sock and Kyrgios continue to make contact with very bent elbow hitting structures. During the turn, they set the upper arm where it needs to be in order to rotate forward into the shot with the body, at a height where it'll drop to produce ESR, with an angle that assures that bent elbow at contact.



When they initiate their drops, they really accentuate the drop of the elbow as the focal point. It drops into the slot, forcing the whole forearm to rotate around it, first externally, then internally.

In fact, take a look at the Sock video that image was pulled from. Really take time to notice the degree to which the stroke is built around the position of that elbow. It leads the stroke back, drops first, and becomes the fulcrum for the whole stroke. Once you notice that, the leading elbow ought to become pretty simple to understand.


  • Unit turn with arm out, elbow bent and high up
  • Elbow drops and body/upper arm "unit" begins to rotate forward, pushing elbow ahead of racquet, creating lag
  • Forearm rotates around upper arm

This differs, incidentally, from the turn you'll see from Del Potro, or Federer, or Nadal. They don't want the racquet arm to drop such that the elbow becomes the focus of rotation. They want the racquet back further, and the elbow straighter, so that when THEY drop from their loop and begin to swing forward, the RACQUET is the primary counterweight (instead of the elbow), which pulls the arm straight. Their ESR/ISR happens around a different axis, rotating the whole arm around the shoulder, rather than rotating the forearm around the upper arm at an angle. So their takebacks lead less (or in Del Potro's case, not at all) with the elbow, and more with the racquet. The upper arm still has to find its slot, but the takeback becomes more about getting the racquet set as a counterweight.

So for straight arms...

  • Unit turn with arm out, racquet leads back high, elbow fairly straight
  • Racquet drops, body/upper arm "unit" begins to turn, weight of racquet pulls arm straight, creating lag
  • Forearm rotates with upper arm, racquet rotates around wrist

TL;DR -- the takeback is about (among other things) putting the part you want to drop first the furthest back, so that your swing's rotation will build around that. For bent-arm hitters, that'll be the elbow. For straight arm hitters, that'll be the racquet.
Wow, thank you. This is first time I run into someone who actually understands the mechanics of forehand swing. I couldn't find this in any books or online videos. Any recommendations for a modern book that explains this in even more detail?
 
#22
Wow, thank you. This is first time I run into someone who actually understands the mechanics of forehand swing. I couldn't find this in any books or online videos. Any recommendations for a modern book that explains this in even more detail?
If it exists, I have never seen it. Most good full-body throwing chain resources come from baseball, so you might want to look there. They won't explain the tennis-specific stuff, but when the basics are well understood, the particulars of any sport simply fall into place. Bodies work the same everywhere.

Chains are hard to understand at first, and hard to execute at first, but once you get them, they're all pretty much the same. Like the rock skipping mentioned above.
 
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