American Twist serve

[DarkMike]

I hit 3 topspin serves straight topspin, topspin slice and american twist. First 2 ball is coes too top of head slightly in front. My hands feels similar motion to when I threw overhand curve ball I know I am hitting up up not over, but that thought works for me. The twist was first serve I learned great second serve. ball placement was directed up thru and back with hand even with my nose. Back arched back knees foward to counterbalance swing went hard across ball while hips snap driving my body and shoulders at side fence. Hard part in teaching it is getting the back snap to get balance and racket speed imo

when i was first learning how to hit this serve myself the back arch balance was probably the hardest part. I decided that i should just move by back leg (your right leg if right handed) behind my body more to give me some balance when i bent my knees to arch back. This meant though that on the ad court i'd have to move a little farther away from the center line to avoid faulting with my feet crossing into the deuce court.

i feel like this particular serve requires more "arm strength" to pull off correctly since you are making contact with the ball so early in your swinging motion instead of making contact later on where you have more momentum and are already about to wrist snap naturally.

 

[chrisb]

when i was first learning how to hit this serve myself the back arch balance was probably the hardest part. I decided that i should just move by back leg (your right leg if right handed) behind my body more to give me some balance when i bent my knees to arch back. This meant though that on the ad court i'd have to move a little farther away from the center line to avoid faulting with my feet crossing into the deuce court.

i feel like this particular serve requires more "arm strength" to pull off correctly since you are making contact with the ball so early in your swinging motion instead of making contact later on where you have more momentum and are already about to wrist snap naturally.

I am also lefty. And yes u have to play around with feet and there is more arm strength The success of the serve is also very dependent on the speed of the back snap. I am 75 now and when I play the next day my lower back has a discussion with my brain

 

[Chas Tennis]

Have you seen one bounce or faced one on the court??

No. Not AT that I know of.

I have seen a few kick serves that bounce to the right (for the server).

I faced a serve with action and that was very difficult to control. I thought that it was a kick serve. A year or two later, I asked the server to my club to video his serve. I now believe that his serve was a top spin serve as I had a second camera looking along the trajectory and only, say, 3 of 30 serves bounced to the right (for server). All bounced very high.

I was specifically looking for the racket to tilt closed (top forward) for a kick serve impact and never saw it. Using Cross's information on the racket tilt, I would expect no racket tilt for a top spin serve so it could be that the experiment worked as it should have but the player was hitting top spin serves.

If you don't have the extra forward racket tilt for impact you should not be able to get the kick to the right.

I faced a server that had an effective kick serve. As I remember it now, it bounced to the right during the match. I videoed a few of his serves and have posted his serve. I saw the characteristic upward motion racket motion but I did not notice the ball bounce to the right on the few that I videoed. Seeing the ball bounce to the right is not always easy so I'm not sure of the bounce.

Note - the upward racket motion is easy to see from behind with 240 fps and small motion blur. But the racket tilt needs the proper camera viewing angle to see the racket closed at about 15 d. See post #12. Camera angle from around doubles sideline and service line projected to doubles sideline.

If anyone has a very good kick serve or American Twist serve and a high speed camera with small motion blur I can give you instructions on how to video it.

 

[SystemicAnomaly]

@DarkMike @myservenow

That's why I think American Twist is more about the FT than the ball-strike. You can impart more or less kick or top depending on the initial path to the ball and the ball strike, independent of the follow through whereas American Twist describes the FT style specifically.

The follow-thru out to the right (for a rightly server) could help some players achieve more of a 'twist' action (side bounce) on their kick serve but it's not absolutely necessary. Fabrice Santoro employed this 'old school' American twist follow-thru. However, Federer does not. Roger has gotten some incredible twist action (side bounce) with a standard FT.

 

[Chas Tennis]

........ So righty pronates out and the racket just stays right side, trails behind on FT. .......................

What is FT?

 

[DarkMike]

@DarkMike @myservenow


The follow-thru out to the right (for a rightly server) could help some players achieve more of a 'twist' action (side bounce) on their kick serve but it's not absolutely necessary. Fabricate Santorini employed this 'old school' American twist follow-thru. However, Federer does not. Roger has gotten some incredible twist action (side bounce) with a standard FT.

That's mainly just for when you are learning it....it helps with giving the player a visual of how their racquet should be moving. Once you understand how the serve works though you can get rid of that follow-thru if you want.

What is FT?

Follow-thru

 

[SystemicAnomaly]

The only people I have ever heard use the term “American twist serve” are older players, probably 60+. It must be an outdated term for a kick serve?

Not really. Have heard "American twist" used by players in their 40s and 50s. But it has been around for well over a century. The "kick serve" terminology seems to be a fairly recent development. Don't recall it being used prior to the 90s. It seems to be a more general term than the older, more specific "twist serve" terminology". 'Twist' is now often used to denote one type or version of the kick serve family family.

 

[SystemicAnomaly]

That's mainly just for when you are learning it....it helps with giving the player a visual of how their racquet should be moving. Once you understand how the serve works though you can get rid of that follow-thru if you want.


Follow-thru

Yeah, that's what I'm sayin'

Fabricate Santorini??? Annoying auto-correct strikes again.

 

[Chas Tennis]

Here are measurements of the spin axis direction and rotation rate of a "kick" serve.

What would we see for an American Twist serve for the resulting spin axis and rotation rate?

Remember that ball spins have just one spin vector (spin vector = direction and spin rate)

 

[IowaGuy]

Here are measurements of the spin axis direction and rotation rate of a "kick" serve.

What would we see for an American Twist serve for the resulting spin axis and rotation rate?

Or, can anyone link to a youtube video showing a twist serve and another showing a kick serve, so that we can be clear of the differences?

 

[VoodooChild24]

Here's how I do it. I'm right handed.

Kick / Slice Serve:
1. Toss a bit behind
2. Hit the ball upwards and force it to go down with follow through
3. Follow though ends of your left side of the body
I mainly use on the deuce court to pull opponent wide on his forehand

Twist:
1. Toss can be behind or a little in front
2. Hit the ball upwards
3. Pronate right away and force the ball to go down with follow through
4 Follow through ends a little bit in front of you
I mainly use on the ad court to pull the opponent wide on his backhand.

*Important - Always explode to the ball when serving!!

It may not be how others do it but this is what works for me.

 

[Chas Tennis]

Or, can anyone link to a youtube video showing a twist serve and another showing a kick serve, so that we can be clear of the differences?

Post #12 shows the racket motion for the kick serve and slice serve from behind, one frame before, one during impact, and one after. I have not found equivalent videos for the kick serve. Also, shown is the racket tilted closed before impact.

We need equivalent videos for the American Twist.

Does the American Twist have similar spin vector as the kick serve and the only difference is how the body moves to produce a similar racket motion on the ball?

 

[Shroud]

No. Not AT that I know of.

I have seen a few kick serves that bounce to the right (for the server).

I faced a serve with action and that was very difficult to control. I thought that it was a kick serve. A year or two later, I asked the server to my club to video his serve. I now believe that his serve was a top spin serve as I had a second camera looking along the trajectory and only, say, 3 of 30 serves bounced to the right (for server). All bounced very high.

I was specifically looking for the racket to tilt closed (top forward) for a kick serve impact and never saw it. Using Cross's information on the racket tilt, I would expect no racket tilt for a top spin serve so it could be that the experiment worked as it should have but the player was hitting top spin serves.

If you don't have the extra forward racket tilt for impact you should not be able to get the kick to the right.

I faced a server that had an effective kick serve. As I remember it now, it bounced to the right during the match. I videoed a few of his serves and have posted his serve. I saw the characteristic upward motion racket motion but I did not notice the ball bounce to the right on the few that I videoed. Seeing the ball bounce to the right is not always easy so I'm not sure of the bounce.

Note - the upward racket motion is easy to see from behind with 240 fps and small motion blur. But the racket tilt needs the proper camera viewing angle to see the racket closed at about 15 d. See post #12. Camera angle from around doubles sideline and service line projected to doubles sideline.

If anyone has a very good kick serve or American Twist serve and a high speed camera with small motion blur I can give you instructions on how to video it.

If the iphone 6 or galaxy 7s works i can film

 

[coupergear]

What is FT?

Follow through

 

[Chas Tennis]

If the iphone 6 or galaxy 7s works i can film

Galaxy 7s says that it does 240 fps.
https://www.samsung.com/uk/support/...mera-mode-on-my-samsung-galaxy-s7-or-s7-edge/

IPhone 6 I think that has high speed video.

One shot from behind looking along the ball's trajectory and showing the bounce. The wide angle lens may make the bounce pretty small. ? See post #12 gifs from behind.

This is easy to get with a zoom lens.

The second shot has to be close enough to see the closed tilt angle of the racket. See post #12 Stosur.

You might get a sleeveless shirt to show you shoulders. Put some blue painter's tape around your upper arm,close to the elbow to directly show ISR.

Video in bright sunlight....

Due to the very large video size at high speed - Warm up and practice kick serve and then video 2-4 serves only. Maybe someone can trigger the camera for you. You could cover only the top half of the body to above the racket on some serves.

 

[SystemicAnomaly]

no a kick and american twist is the same serve...it just happens that some people are able to give it a stronger side spin allowing the ball to "jump back" while others don't have enough side spin and it instead curves and then essentially becomes a topspin serve after the bounce and jumps towards the baseline or has a very weak "back jump".

Edit* Unless we are calling a serve with only top spin a kick serve and a serve with diagonal top spin a twist.

Not exactly. Kick refers to a general class of serves. (A number of sources consider “kick” to be an ambiguous term). American twist is a type of kick serve. In other words, American twist is a subset of a larger set known as kick serves.

Also, side spin (vertical-axis spin) accounts for the left/right deviation in the trajectory of the ball prior to the bounce but it does not cause the ball to move in the opposite direction on the bounce. The directional change at the bounce is due to the presence of spiral spin (z-axis spin).

 

[SystemicAnomaly]

@Curious @Shroud

I think it helps to think about the physics involved. If you hit a slice serve the ball is rotating mostly horizontally, and this reduces the pressure on one side of the ball relative to the other side. This allows one side of the ball to move through the air more efficiently than the other and the ball moves sideways (from right to left for a right hander). This is called the Magnus Effect. Gravity is also pulling down on the ball, which has an effect not only on the path of the ball but on the spin too. With each rotation the direction of the spin is changing to become a little more vertical. As the ball is being pulled downward (one side of the ball is rotating a little bit toward the direction of the gravitational force, and the other is rotating away. So gravity is pulling a little harder on one side than the other, which starts to change the direction of spin (assuming you don't have perfectly horizontal spin, which you don't). So gravity wants to convert slice spin to top spin.

For the AT serve you have start out with just enough slice to cause the ball to move right to left in the air, and then let gravity start to convert this to top spin which causes the ball to hit the ground in a manner where the flight path of the ball does not match the spin anymore. If you have to much slice spin on the ball then the ball hits the ground moving to the left and the spin takes it to the left. To much top spin and the ball is moving straight and bounces straight. But if you have just the right amount of slice on it then the ball is moving through the air to the left, but by the time the ball lands its spin has changed into mostly top spin that wants to take the ball to the right off the bounce even as the ball is still moving left in the air. And you get a jump in the wrong direction. If you hit this from the add court, standing out wide the effect is more dramatic because the ball is moving more in the direction of the bounce you want to begin with.

This means to hit it right you have to have a lot of spin on the ball and you have to hit it relatively slowly to give gravity time to work, and you have to enough but not too much slice spin on the ball initially. All this said, I can occasionally hit one but not on purpose. It's difficult to master.

Very good explanation but it is missing a key element. That is, the presence of Z-axis spin. Physicist, Rod Cross, has referred to this as gyrospin (in his TWU articles) and as spiral spin or spiralspin (in his tennis physics books).

The spin axis for (conventional) sidespin and for topspin (& backspin) is perpendicular to the flight path/direction of the ball. Because of this there is an associated Magnus effect with these types of spin. However, the spin axis for spiral spin is directly in line with the ball trajectory. Because of this there is no associated Magnus effect for this spin type. That is why there is no left/right trajectory deviation for a badminton shuttle or an American football pass (unless there is a cross wind present).

However, it is the presence of spiral spin that is responsible for the side bounce that is seen on twist serves, some drop shots and some other specialty shots. Contrary to what some sources claim, (vertical-axis) sidespin does NOT account for a directional change at the bounce. In fact,for a twist serve, side spin causes a trajectory deviation (prior to the bounce) in one direction while spiral spin causes a directional change in a different (opposite) direction at the bounce. According to Rod Cross, conventional sidespin has no effect on bounce direction.

Now for the really interesting part...

According to several sources, there is actually only a very small component of spiral spin present for a twist serve when the ball leaves the server’s racket. The resultant spin axis is very nearly perpendicular to the direction of the ball. However, as the ball travels thru the air, the spiral spin component increases — if there is a sufficient amount of spin (topspin + sidespin) present at the onset. As you suggest, the presence of gravity might change the nature of the spin. Gravity (or drag) might convert some of the initial spin into spiral spin. This would mean that the resultant spin axis, just prior to the bounce, is now offset quite a bit from perpendicular to the ball’s flight direction.

 

[SystemicAnomaly]

I can kick serve all day long. No matter what you call it, there is a difference between a kick serve and an American Twist serve. The AT is probably just an advanced variant of the kick serve. The best way to describe it is the ball seems to loop up over the net and dives down into service box. From the server’s perspective, the ball appears oblong and misshaped as it flies through the air and jumps high and away from the returner once it hits the court. It almost seems to jump sideways off of the court. When someone hits one at you, you definitely know it is a different kind of serve. My high school coach (who is no longer around to ask how) was an evil expert on the American Twist...

The oblong shape and trajectory you describe suggests a very high rate of spin. A very high spin rate and a moderatly high spin rate could very well be the most significant factor that separates a good twist serve from a kick serve that does not have as much twist action (side bounce).

Ok, but how's that different from a regular kick serve? I feel like I do all these things but usually no twist.

You might very well have the proper swing mechanics for a twist serve but not quite enough RPMs to elicit the twist action. It could be that it takes a very high spin rate (as well as the presence of both topspin and sidespin) to yield enough spin conversion to spiral spin for a side bounce.

For a sufficient spin rate you need a very fast brushing action (a glancing blow, if you will). This type of brush action has a telltale sound. It sounds quite a bit different than most ball contacts. Here are some novelty shots (but no twist serves) that exhibit the very fast brushing sound

Listen at 1:37

Underarm serves with a fast brush sound. (These also employ spiral spin).

 

[Chas Tennis]

........... The directional change at the bounce is due to the presence of spiral spin (z-axis spin).

This is tricky.

Flat, slice and kick serves all have spiral spin also know as gyrospin. This is shown in the ball spin data. Dashed lines AVx shown spiral or gyro spin component for each type of serve showing that significant gyrospin is present for all 3 types of serves.

Now print the diagram and draw the 3 spin axis lines down through the ball and out the bottom. Look at how they come out the bottom. Imagine the spinning ball as it first touches the court. Consider the felt speed and direction as it would impact the court. The felt is moving faster for a kick serve than for a slice or flat serve 1) because of the spin rate and 2) mostly because the felt is farther from the spin axis for the kick serve compared to the slice or flat serves. Compare especially to slice serve regarding how far the felt on the court is from the spin axis. And also the kick impact will be more forceful, more squish, because of the kick serve's large angle of impact with the court. More detail of the collision would take a high speed video study.

You could also drill holes through a tennis ball and stick a pencil, nail or other thing rod the ball as an axis. Examine the velocity of the felt on the court as the axis is tilted. The tilt of the kick serve axis is shown by the ball diagram above.

 

[Chas Tennis]

@Curious @Shroud
................ As you (and @[COLOR=#ff0000]Chas Tennis[/COLOR]) suggest, the presence of gravity will change the nature of the spin. Gravity is believed to convert some of the initial spin into spiral spin. This would mean that the resultant spin axis, just prior to the bounce, is now offset quite a bit from perpendicular to the ball’s flight direction.

I don't have that view. I believe that the spinning ball acts like a gyroscope and maintains the direction of the spin axis over a short distance to the bounce.

I believe what Rod Cross has stated that the spin axis of the serve remains about the same from the serve to the court bounce. It may be in the Physics of the Kick Serve Article. That article has a lot of information but it is scattered and hard to relocate. If you find something mark a paper copy.

 

[Dan R]

@Curious @Shroud




According to several sources, there is actually only a very small component of spiral spin present for a twist serve when the ball leaves the server’s racket. The resultant spin axis is very nearly perpendicular to the direction of the ball. However, as the ball travels thru the air, the spiral spin component increases — if there is a sufficient amount of spin (topspin + sidespin) present at the onset. As you (and @Chas Tennis) suggest, the presence of gravity will change the nature of the spin. Gravity is believed to convert some of the initial spin into spiral spin. This would mean that the resultant spin axis, just prior to the bounce, is now offset quite a bit from perpendicular to the ball’s flight direction.

I think I agree with what you are saying, but I'm not entirely sure what you mean by spiral spin or Z-Axis spin? To me it seems like you can define spin with two axises, call them X and Y, alone, where pure side spin is about the X axis and pure top spin or under spin is spin about the Y axis. In actuality most balls will be spinning with some combination of these two components. Is that what you mean by spiral spin?

I've always assumed the reason that a football does not change direction is because it's too heavy and spinning too slowly to have a noticeable effect. I would assume the Magnus Effect is still present. After all a tennis ball hit with pure topspin hit in the direction of spin will still bend - it bends downwards.

Thanks for the explanation.

 

[SystemicAnomaly]

I don't have that view.

I believe what Rod Cross has stated that the spin axis of the serve remains about the same from the serve to the court bounce. It may be in the Physics of the Kick Serve Article. That article has a lot but the information is scattered and hard to relocate. If you find something mark a paper copy

Sorry, I misspoke about what you had said. I had quickly glanced at one of your long posts and misinterpreted what you were saying. A more conscientious reading revealed your true intent.

I believe that you are correct about the claim that R Cross made in saying there was little (or no) change in the orientation of the spin axis during the ball’s flight (prior to the court bounce). However, there have been some physicists (in these forums and elsewhere) who have disagreed with some of the details & conclusions that Cross has made. One of these was Anatoly Antipin (aka toly).

There was another physicist who posted here a few years back who had indicated that the spin axis for a twist serve did, indeed, change during the flight of the ball prior to its bounce. I don’t remember that individual’s name. Do you recall? He had indicated that the spiral spin component was very mild at the onset (just off the racket) but increased during flight, particularly for very high spin rates. He had indicated that gravity was a factor in this increase. He might have also mentioned air drag as a factor. Could probably find his posts if we can recall his name. I do recall another source that backed up his assertions but not sure that resource is still accessible online (not been able to find it).

Bullet ballistics also bring up some interesting details wrt respect to spin axis and trajectory changes or anomalies. They speak of spin drift, gyroscopic precession, the Poisson Effect, a Coriolis Effect, Magnus Effect and, perhaps, some other dirty details.

 

[SystemicAnomaly]

<— select for larger image​

I think I agree with what you are saying, but I'm not entirely sure what you mean by spiral spin or Z-Axis spin? To me it seems like you can define spin with two axises, call them X and Y, alone, where pure side spin is about the X axis and pure top spin or under spin is spin about the Y axis. In actuality most balls will be spinning with some combination of these two components. Is that what you mean by spiral spin?

I've always assumed the reason that a football does not change direction is because it's too heavy and spinning too slowly to have a noticeable effect. I would assume the Magnus Effect is still present. After all a tennis ball hit with pure topspin hit in the direction of spin will still bend - it bends downwards.

Thanks for the explanation.

Nope. Spiral spin (gyrospin) is a 3rd component. Most ball flights that we experience in tennis have negligible spiralspin so we can think the resultant spin axis as having only 1 or 2 components. However, the twist serve and some other specialty shots have this additional component. This type of spin is fairly common in ping pong and is often referred to as corkscrew spin (or simply, cork spin).

What I call Z-axis spin spiral spin) is the type of spin that has an axis of spin directly in line with the path of the ball. (Physicist, Rod Cross, might use a different axis naming convention). It is akin to Roll for a jet or airplane (Yaw corresponds to side spin and Pitch relates to topspin and backspin).

Think of the type of spin on a badminton shuttle or an American football (pass). Their spin axis is in the direction of flight. No Magnus Effect present for this type of spin. Rod Cross explicitly states this in his book, Technical Tennis, and elsewhere. The weight of the football has nothing to do with the lack of left/right deviation. Badminton shuttles are very light and experience no left right deviation (unless acted on by a cross wind).

It is because shuttles and (American) footballs do not normally have a sidespin component, they do not experience a left/right bend in their trajectories. OTOH, soccer (futbol) players can often impart side spin to the ball so they can achieve this deviation. Bend it like Beckham. Note that a soccer ball has a weight that is comparable to an American football.

With a vertical-axis sidespin, a high air pressure develops on one side of the ball and a low pressure develops on the other side — depending on which way the ball is spinning. The ball bends toward the low pressure side. This is the Magnus effect. For topspin, the higher pressure is on the upper half of the ball so the ball tends to dip down toward the lower pressure.

Where would the high and low pressures develop for a pure Z-axis spin? Pressure is the same in all directions for this type of spin = no net effect = no Magnus Effect.

For a ball spin with a negligible spiralspin component, the spin axis is merely some combination of a sidespin component and a topspin component. That resultant spin axis is in the XY plane which is perpendicular to the flight direction of the ball. However, with a significant Z-axis component, the resultant spin axis is no longer perpendicular. The late Kathy Krajco spoke of this altered (twisted) spin axis for a twist serve on her excellent web site, Operation Doubles. Sadly, her OD site was taken down some time after her passing. Much, but not all, is available as archived pages. Although Kathy wrote about the twisted spin axis, she did not refer to the 3rd spin component by name.

web.archive.org/web/20070928002805/http://www.operationdoubles.com/spindoctoringserve.htm
web.archive.org/web/20071023034536/www.operationdoubles.com/od-tennis_content.htm

 

[SystemicAnomaly]

Gyrospin (spiralspin) is very apparent for the baseball pitch on the right. I have seen some discussions of gyrospin in baseball by both Japanese and physicists. No Magnus effect.

Slider pitches (pitching machine on L, pitcher on R)

https://www.drivelinebaseball.com/2016/11/spin-rate-part-ii-spin-axis-useful-spin/
https://www.fangraphs.com/blogs/qa-alan-nathan-on-the-physics-of-pitching/

Quote from 2nd link: “A pure gyroball is one that is thrown with so called bullet spin. A gyroball basically doesn’t break, In fact, there’s no movement to it.”

Note that spiral spin is usually imparted to bullets (by "rifling" the barrel) and sometimes with arrows (by virtue of feather construction). This is to stabilize their flight -- no (or minimal) Magnus Effect. However for very long distance trajectories, some Magnus or other effect will creep in.

 

[Chas Tennis]

I think I agree with what you are saying, but I'm not entirely sure what you mean by spiral spin or Z-Axis spin? To me it seems like you can define spin with two axises, call them X and Y, alone, where pure side spin is about the X axis and pure top spin or under spin is spin about the Y axis. In actuality most balls will be spinning with some combination of these two components. Is that what you mean by spiral spin?

I've always assumed the reason that a football does not change direction is because it's too heavy and spinning too slowly to have a noticeable effect. I would assume the Magnus Effect is still present. After all a tennis ball hit with pure topspin hit in the direction of spin will still bend - it bends downwards.

Thanks for the explanation.

Look up some references and terms outside of the forum.

 

[Wise one]

Have played tennis going on on 3 decades but have never been able to hit the American Twist serve. Can someone list 3 or 4 pointers that one should focus on when trying to hit the American Twist? Things such as grip, stance, toss, swing, contact point, etc. I am not too far off from being able to hit this serve myself, but so far cannot get that huge change of direction twist kick of the ball once it bounces. My competitive tennis days are mostly over but would love to pass this weapon down to my kids who are just now picking up the game.

Holcomb Ward, 1897.