Torso rotation does NOT precede the swing.

HunterST

HunterST

Hall of Fame
There seems to be the common opinion that core rotation "catapults" the arm forward on the swing, specifically the forehand.

When I watch slow motion video, this just doesn't seem to be the case. Instead, it looks like the rotation and the swing happen simultaneously.

http://www.youtube.com/watch?v=tZNfUTnBjAk

This video shows clearly that dimitrov's uncoiling in the core does not precede the forward swing. The rotation and swing begin at the same time.
 
P

ProgressoR

Hall of Fame
I have not looked at the chain in slow motion before but I looked at this frame by frame and it appears while he drops his racket and begins the forward hitting part of the stroke, his hips dont push forward, however when the arm reaches the point where he whips it forward, he does use his hip to accelerate that.

I dont know if all the top players do this, but it is clear the acceleration is powered by his hips and core - when he needs the acceleration, not before.
 
Cheetah

Cheetah

Hall of Fame
HunterST said:
There seems to be the common opinion that core rotation "catapults" the arm forward on the swing, specifically the forehand.

When I watch slow motion video, this just doesn't seem to be the case. Instead, it looks like the rotation and the swing happen simultaneously.

http://www.youtube.com/watch?v=tZNfUTnBjAk

This video shows clearly that dimitrov's uncoiling in the core does not precede the forward swing. The rotation and swing begin at the same time.
Click to expand...

Toly alert!!
You posted a video where it almost appears that dmitrov is purposely swinging that way to prank tw members and then claim that's how all fh's work. haha. that's what toly would do lol

Watch videos of other players especially the top 4 or top 3 plus fed or most other players for that matter. The effect is more noticeable. Of course you don't have to swing that way but most do. (pros). Even Byrdych.
The core rotation swings the racquet, no doubt about it. That's why you can notice a slight lag. Upper arm usually stays with the side of the core or the ribcage. rotation slows down or stops before impact which throws the hitting arm around.

You will usually only see this on players with quite good forehands or with kids who are young and started playing young because they are loose. I often see 9 10, 11 year olds swing like this. Everyone else usually has a less 'whippy' fh.
 
Fugazi

Fugazi

Professional
HunterST said:
There seems to be the common opinion that core rotation "catapults" the arm forward on the swing, specifically the forehand.

When I watch slow motion video, this just doesn't seem to be the case. Instead, it looks like the rotation and the swing happen simultaneously.

http://www.youtube.com/watch?v=tZNfUTnBjAk

This video shows clearly that dimitrov's uncoiling in the core does not precede the forward swing. The rotation and swing begin at the same time.
Click to expand...
Look at the Fed vid in the suggested vids below. Hips do open slightly before the arm.
 
B

boramiNYC

Hall of Fame
those are truly beautiful fh! thanks for sharing. this is nearly perfect modern E fh.

the rotation as well as the forward weight transfer are done with the feet and the hip, torso, and shoulder rotates mostly as a unit in this vid. when he explodes off the ground to hit much harder he'll use more hip rotation from more open stance to generate even more rotational force along with the scissor kick to balance out the upperbody rotation. but for practice this will do.
 
SystemicAnomaly

SystemicAnomaly

Bionic Poster
Fugazi said:
Look at the Fed vid in the suggested vids below. Hips do open slightly before the arm.
Click to expand...

Don't yet see the suggested vids. However in studying FHs of Federer, Nadal and others, I definitely detect a racket head lag -- the torso starts to uncoil as the racket head is dragged for a short time. This lag/drag stretches the pectoral muscle (as well as muscles on the inside of the forearm). This stretch keeps some energy stored in the pec muscle at the start of the forward swing. After a short (drag) time, the stretch is released -- the arm is catapulted forward which gets the arm & racket moving faster than the torso turn. It happens quickly (even in slo-mo) so you might miss it if you blink.

http://www.youtube.com/watch?v=OKtZudSpFMg
http://www.youtube.com/watch?v=rAyQ0eP0Eh0
 
D

dominikk1985

Legend
HunterST said:
There seems to be the common opinion that core rotation "catapults" the arm forward on the swing, specifically the forehand.

When I watch slow motion video, this just doesn't seem to be the case. Instead, it looks like the rotation and the swing happen simultaneously.

http://www.youtube.com/watch?v=tZNfUTnBjAk

This video shows clearly that dimitrov's uncoiling in the core does not precede the forward swing. The rotation and swing begin at the same time.
Click to expand...

I see what you mean but I don't think it is a good thing. his arm slightly leads his hip rotation. however I believe that might be because him hitting just an easy practise. does he do that in games too? he also uses an over the shoulder finish which I'm pretty sure he is not using in games (fed sometimes does that in practise too, sometimes even catches the racket but in games he will finish at his hip or side like all top100pros).

of course much of the rotation occurs still simultaniously but I believe that the hips should at least start a little bit before the arm starts to go forward. that will not be a huge lag (like a discus thrower) because you still have to be on time for the ball but it should be there although it might be so little that you hardly see it.

but certainly you can see that the racket is still going back as the hips rotate.
 
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tennis_balla

tennis_balla

Hall of Fame
Basically what happens is, when the racket head drops the hips start to open up. The racket has yet to move forward, or is just about to. The uncoiling of the hips are leading the racket. Also, its easier to drop racket head and point buttcap at the ball when you lead with the hip, even just slightly. A tennis ball is not hit in an ideal environment each and every time, unlike what toly thinks. Sometimes things will happen more, less etc. More shoulder turn, less shoulder turn, more racket head drop, less, more topspin, less topspin....I can go on.
If the player is hitting off a more neutral stance the hips and racket aren't that far off from each other, however it gets more noticeable and exaggerated for lack of a better word the more a player hits from a semi-open or open stance. Thats my take on it.
The uncoiling of the hips creates your so called racket lag.
 
C

Chas Tennis

G.O.A.T.
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D

dominikk1985

Legend
Counter said:
Could this comment from another 'lag' thread be relevant?



Comment taken from this thread:
http://tt.tennis-warehouse.com/showthread.php?t=474921
Click to expand...

well of course the arm lag is very small. you still need to be on time with the ball and quickness is just as important as top end speed.

But I still think there is a tiny bit of arm lag even if it is so small that it is hardly visible.

most lag is certainly in the racket because the racket speed is much greater than the hand speed. losing 1-2 mph of hand speed can be tolerated if you get enough stretch in your forerarm to create that RHS. so even if a player doesn't use the SSC in the shoulder/pec area perfectly he can still swing very fast if he uses the SSC in the forearm/wrist area correctly.
 
bad_call

bad_call

Legend
tennis_balla said:
Basically what happens is, when the racket head drops the hips start to open up. The racket has yet to move forward, or is just about to. The uncoiling of the hips are leading the racket. Also, its easier to drop racket head and point buttcap at the ball when you lead with the hip, even just slightly. A tennis ball is not hit in an ideal environment each and every time, unlike what toly thinks. Sometimes things will happen more, less etc. More shoulder turn, less shoulder turn, more racket head drop, less, more topspin, less topspin....I can go on.
If the player is hitting off a more neutral stance the hips and racket aren't that far off from each other, however it gets more noticeable and exaggerated for lack of a better word the more a player hits from a semi-open or open stance. Thats my take on it.
The uncoiling of the hips creates your so called racket lag.
Click to expand...

^ this...more or less.
 
B

boramiNYC

Hall of Fame
IMO Dimitrov's stroke should be emulated by all E fh grip players. his is slightly more old school than Feds but in a good way. in some ways I like it better than Feds.
 
Fugazi

Fugazi

Professional
dominikk1985 said:
I see what you mean but I don't think it is a good thing. his arm slightly leads his hip rotation. however I believe that might be because him hitting just an easy practise. does he do that in games too? he also uses an over the shoulder finish which I'm pretty sure he is not using in games (fed sometimes does that in practise too, sometimes even catches the racket but in games he will finish at his hip or side like all top100pros).

of course much of the rotation occurs still simultaniously but I believe that the hips should at least start a little bit before the arm starts to go forward. that will not be a huge lag (like a discus thrower) because you still have to be on time for the ball but it should be there although it might be so little that you hardly see it.

but certainly you can see that the racket is still going back as the hips rotate.
Click to expand...
+1, this is very relaxed hitting.
 
T

toly

Hall of Fame
I’ll try to simplify the matter as much as possible.
There is picture of unrealistic FH setup.

10rlgyr.jpg


The arm is behind shoulders. The torso rotates around point O with constant angular velocity. C is the arm center of mass. The torso rotation creates centrifugal force Fc which consists of two forces F1 and F2. If ϕ>0, the force F2>0 as well. The force F2 makes the arm to rotate counterclockwise (forward). Thus, if the arm is behind shoulders, the torso rotation can catapult the arm forward. If the arm is in line with shoulder F2=0 and torso rotation does nothing. If ϕ<0, the force F2<0 and will push the arm in clockwise direction.

Thus, in case of real FH the torso cannot catapult the arm forward.
 
Last edited:
T

toly

Hall of Fame
RockChalkOhio said:
It does precede the swing if you rotate your torso before you swing.
Click to expand...
All pros usually starts forward torso and arm rotation as unit with ϕ<=0. So, F2 always will be negative and cannot move arm forward. We must use corresponding muscles actively to rotate the arm in counterclockwise direction.:)
 
L

LeeD

Bionic Poster
I watched HermannBauer, and ex A/Open player, working on his forehands after and extended injury....with Kiteboard, a few years ago.
He led mainly with his torso twist, a split second before the initial shoulder tightening leading to the forward swing. Both were emphatic to work this sequence, as it's good practice and WILL slip upon point play, back to a swing close to the original vid.
And when pressured, tense, important points, lots of TOP players use mostly ARM to make sure they get precise ball contact early enough without an overswing.
Forehands, and any other stroke, are NOT hit exactly the same way every time against different balls in different situations. That is what separates the good players from the bad.
 
KillerServe

KillerServe

Banned
What's most astonishing about all of the videos posted here is that none of the guys seem to be really bringing the racquet from beneath the ball, i.e. low to high. Almost all seem to be hitting flat in a straight line behind the ball and it is only the fact that contact is made so much out in front that the racquet is traveling upward at the point which creates the 'low to high' motion and topspin.
 
B

boramiNYC

Hall of Fame
KillerServe said:
What's most astonishing about all of the videos posted here is that none of the guys seem to be really bringing the racquet from beneath the ball, i.e. low to high. Almost all seem to be hitting flat in a straight line behind the ball and it is only the fact that contact is made so much out in front that the racquet is traveling upward at the point which creates the 'low to high' motion and topspin.
Click to expand...

esp true for E fh. realizing this and applying will make a E fh instantly better.
 
L

LeeD

Bionic Poster
Killerserve....
A forehand hit with topspin often does NOT have a purely low to high swingpath, but usually shows SOME amount of that and a slightly closed racketface.
A lower level topspin shot has pronounced low to high swing...which is why it's lower level.
That said, Nadal has a low to high swingpath.
Federer's is flatter, as is Delpos and lots of the pros.
The finish is very important to adding the topspin rotation of the ball.
 
R

rkelley

Hall of Fame
toly said:
I’ll try to simplify the matter as much as possible.
There is picture of unrealistic FH setup.

10rlgyr.jpg


The arm is behind shoulders. The torso rotates around point O with constant angular velocity. C is the arm center of mass. The torso rotation creates centrifugal force Fc which consists of two forces F1 and F2. If ϕ>0, the force F2>0 as well. The force F2 makes the arm to rotate counterclockwise (forward). Thus, if the arm is behind shoulders, the torso rotation can catapult the arm forward. If the arm is in line with shoulder F2=0 and torso rotation does nothing. If ϕ<0, the force F2<0 and will push the arm in clockwise direction.

Thus, in case of real FH the torso cannot catapult the arm forward.
Click to expand...

I don't agree with this analysis. Fc, which Toly called centrifugal force, doesn't exist, therefore all the components of that force don't exist either. The arm has a forces at the shoulder where it connects with the body, and it has it's own weight. That's it.

If you turn your body about your core, the general reaction to anything attached to your body is that it has to move as well (or break the connection). As your body rotates your shoulder will rotate. If you tense the muscles in your shoulder your arm will rotate around with your body. If you relax those muscles your arm will lag behind your body until it gets to that point where it has to start rotating with your shoulders or the joint starts being damaged.

More generally centrifugal force is not real. When you're in a car that's going around a corner, people often say they feel centrifugal force. What they're really feeling is that their body wants to continue going in a straight line, but the car is turning. It feels like your body is being thrown to the outside of the arc of the turn, but really the car is pushing your body into the center of the arc of the turn. This is called centripetal force, and is real.

Hope that helps.
 
S

sureshs

Bionic Poster
KillerServe said:
What's most astonishing about all of the videos posted here is that none of the guys seem to be really bringing the racquet from beneath the ball, i.e. low to high. Almost all seem to be hitting flat in a straight line behind the ball and it is only the fact that contact is made so much out in front that the racquet is traveling upward at the point which creates the 'low to high' motion and topspin.
Click to expand...

Yes someone pointed out that the slope of the swing is not steep at all. It is not easy to do this, BTW.
 
S

sureshs

Bionic Poster
rkelley said:
I don't agree with this analysis. Fc, which Toly called centrifugal force, doesn't exist, therefore all the components of that force don't exist either. The arm has a forces at the shoulder where it connects with the body, and it has it's own weight. That's it.

If you turn your body about your core, the general reaction to anything attached to your body is that it has to move as well (or break the connection). As your body rotates your shoulder will rotate. If you tense the muscles in your shoulder your arm will rotate around with your body. If you relax those muscles your arm will lag behind your body until it gets to that point where it has to start rotating with your shoulders or the joint starts being damaged.

More generally centrifugal force is not real. When you're in a car that's going around a corner, people often say they feel centrifugal force. What they're really feeling is that their body wants to continue going in a straight line, but the car is turning. It feels like your body is being thrown to the outside of the arc of the turn, but really the car is pushing your body into the center of the arc of the turn. This is called centripetal force, and is real.

Hope that helps.
Click to expand...

Even before we come to that, I don't think the arm can go behind the shoulder like in his diagram :) At least my arm doesn't go more than 20 degrees back if I am facing forward.
 
Power Player

Power Player

Bionic Poster
Yes, that is one heck of a takeback. Looks a little painful. I think it is a model of Fed's but I may be wrong. Fed has some serious flex in his arm.
 
S

sureshs

Bionic Poster
toly, I don't follow why even if the arm is back, the ball cannot be hit forward.

Firstly, you don't show the torso rotated.

Secondly, forward is not the direction F2, unless the player allows the ball to come behind him. If he keeps his arms behind and rotates his torso around, won't your entire diagram just swing around and hit the incoming ball forward?
 
R

rkelley

Hall of Fame
I think Toly's point is that force F2 will create a moment that rotates the arm relative to the body while force F1 just pulls on the arm and will not create a moment (since it's in line with the pivot - i.e. the shoulder).

It's a moot point though since the force Fc doesn't exist.
 
T

TennisCJC

Legend
ProgressoR said:
I have not looked at the chain in slow motion before but I looked at this frame by frame and it appears while he drops his racket and begins the forward hitting part of the stroke, his hips dont push forward, however when the arm reaches the point where he whips it forward, he does use his hip to accelerate that.

I dont know if all the top players do this, but it is clear the acceleration is powered by his hips and core - when he needs the acceleration, not before.
Click to expand...

I pretty much agree. At full speed, it looks like core and arm are "in sync", but I think it flows from the ground up: legs, core to arm. But, it also is a coordinated chain and it does flow together and not a forced or pronounced lag.
 
KillerServe

KillerServe

Banned
sureshs said:
Yes someone pointed out that the slope of the swing is not steep at all. It is not easy to do this, BTW.
Click to expand...

Can you please explain why you say it's not easy? What is difficult about it? Do you mean timing it so the contact occurs when the racquet is just beginning to travel upwards?
 
S

sureshs

Bionic Poster
KillerServe said:
Can you please explain why you say it's not easy? What is difficult about it? Do you mean timing it so the contact occurs when the racquet is just beginning to travel upwards?
Click to expand...

The timing is difficult and the distance from the ball has to optimal for the straight arm
 
HunterST

HunterST

Hall of Fame
Power Player said:
Hips and core power the swing, but believe what you want.
Click to expand...

I believe that. I was just saying that, from the footage I've seen, the hips catapulting the arm forward doesn't seem to happen.

I think tennis balla had a good point. It doesn't happen much in a neutral stance, but as the stance opens up, the lag gets more pronounced.
 
B

boramiNYC

Hall of Fame
KillerServe said:
Can you please explain why you say it's not easy? What is difficult about it? Do you mean timing it so the contact occurs when the racquet is just beginning to travel upwards?
Click to expand...

I don't think it makes it more difficult. just the opposite after you get used to it because E grip is optimum for swiping across instead of lifting up. but the stance, weight shift, and more closed shoulder (to prevent too open) should be corrected and refined all together for best effect.
 
H

hawk eye

Hall of Fame
Yes you initiate the forward swing with you hips, torso.
But after that the acceleration of the arm is not a passive thing, on the contrary. If you're doing it right, the velocity is highest just before/ at impact. Just after impact things should slow down. Or else you're spoiling energy. Some people reach their max swing speed well before they meet the ball. In most of these cases there's a large backswing.
But then again you can still hit them hard. Timing is everything.
 
R

rkelley

Hall of Fame
hawk eye said:
Yes you initiate the forward swing with you hips, torso.
But after that the acceleration of the arm is not a passive thing, on the contrary. If you're doing it right, the velocity is highest just before/ at impact. Just after impact things should slow down. Or else you're spoiling energy. Some people reach their max swing speed well before they meet the ball. In most of these cases there's a large backswing.
But then again you can still hit them hard. Timing is everything.
Click to expand...

Velocity of the arm or the racquet?

The velocity of the arm at impact should be pretty low, while the racquet should be moving fast. This is the whole idea of kinetic chain. Look at the Fed video. His arm is almost stationary at contact. The racquet is moving fast however, which is what matters.
 
T

toly

Hall of Fame
sureshs said:
Even before we come to that, I don't think the arm can go behind the shoulder like in his diagram :) At least my arm doesn't go more than 20 degrees back if I am facing forward.
Click to expand...
Can you read my post more carefully? In my post I said, “There is picture of unrealistic FH setup.” This helps to demonstrate angle ϕ.
 
T

toly

Hall of Fame
rkelley said:
I don't agree with this analysis. Fc, which Toly called centrifugal force, doesn't exist, therefore all the components of that force don't exist either. The arm has a forces at the shoulder where it connects with the body, and it has it's own weight. That's it.

If you turn your body about your core, the general reaction to anything attached to your body is that it has to move as well (or break the connection). As your body rotates your shoulder will rotate. If you tense the muscles in your shoulder your arm will rotate around with your body. If you relax those muscles your arm will lag behind your body until it gets to that point where it has to start rotating with your shoulders or the joint starts being damaged.

More generally centrifugal force is not real. When you're in a car that's going around a corner, people often say they feel centrifugal force. What they're really feeling is that their body wants to continue going in a straight line, but the car is turning. It feels like your body is being thrown to the outside of the arc of the turn, but really the car is pushing your body into the center of the arc of the turn. This is called centripetal force, and is real.

Hope that helps.
Click to expand...
The reality or not of the force I’m not going to discuss, this forum is not proper place. Rod Cross used centripetal force and got the same result wrt forearm and hand/racquet. See article,
Wrist Snap In the Serve -http://www.racquetsportsindustry.com/articles/2006/07/wrist_snap_in_the_serve.html
 
R

rkelley

Hall of Fame
toly said:
The reality or not of the force I’m not going to discuss, this forum is not proper place. Rod Cross used centripetal force and got the same result wrt forearm and hand/racquet. See article,
Wrist Snap In the Serve -http://www.racquetsportsindustry.com/articles/2006/07/wrist_snap_in_the_serve.html
Click to expand...

I quickly looked at the article and I didn't see a problem with it. I don't see where you and he are saying the same thing. Could you be more specific?
 
T

toly

Hall of Fame
rkelley said:
I quickly looked at the article and I didn't see a problem with it. I don't see where you and he are saying the same thing. Could you be more specific?
Click to expand...
According to Rod Cross, if hand is behind forearm, arm rotation around shoulder creates (positive/good) motion dependent torque which pushes the hand in counterclockwise direction, so it provides additional acceleration and RHS. That’s why we should extend the hand to get passive racquet snap in flexion direction.

In case of the arm and torso rotation, pros actively keep the arm ahead of shoulder. Thus we have (negative/bad) motion dependent torque which pushes the arm in clockwise direction. So, there is no arm snap (“catapult effect”).
 
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