Looping

[brokenball]

I found this vide. It shows how Timo Boll likes to loop. Timo Boll explains what the body must do to make a good loop. What he doesn't explain is that he has found, by trial and error, the best timing/conditions when to hit the ball and where on the ball to make contact.
Timo is making a real loop. The ball is hit from a low position and he is relying on the Magnus effect due to spin to bring the ball back down on the table. How fast do you think he needs to hit the ball? What Timo Boll has figured out is that it is the correct ratio of speed to spin that makes a winning loop. I don't consider what most of you call a loop, a loop. It is just a ball with top spin. BTW, I am tool old to get as low as Timo. I don't think it is necessary to get that low. What is necessary is to have the ball pass over the net as low as possible because the ball will bounce up about 80% of it maximum height. It is to bad I can't see the ball land in the video.

 

[Tinykin]

Off the top of my head,Forms of topspin strokes:

• Flick. banana flick - quick shot with high speed. Usually over the table against incoming backspin or floaty backspin
• Roll - low spin and speed - lower speed and spin compared to flick. just after bounce or top of arc when over the table.
• Smash - high speed with little regard to spinning the ball
• Punch - same as smash but using a stroke visually similar to someone punching
• Loop - versatile shot usually used away from the table against either incoming backspin or topspin or floaty balls or low/high balls or below/above the table.Resulting ball may be high or low spin or speed. The stroke action itself tends to be long as compared to the drive thus allowing the opportunity to disguise the amount or ratio of spin to speed.

 

[ttarc]

How fast? We can approximate that.From Kinematic Parameters of Topspin Forehand in Table Tennis and Their Inter- and Intra-Individual Variability https://www.jssm.org/volume19/iss1/cap/jssm-19-138.pdf we get "Studies related to the evaluation of kinematic and kinetic parameters of this stroke have demonstrated that at impact, the ball is hit by a racket moving forward and upwards at a resultant speed of approximately 20 m/s. The acceleration of the racket at the time of contact is approximately 180 m/s²..."
Lets say a push results in a ball going forward with 10 m/s and travels maybe 3 m before being hit = 300 ms.
Lets say Timo can react in 200 ms 1) 100 ms to accelerate -> 180 m/s² * 0.1 s = 18 m/s or 64.8 km/h or around 40 mph.
"The study examined seven top-ranked (international level) Polish adult male table tennis players" that were able to achieve 161.2 m/s² +- 4.6 in topspins against backspin 161.2 m/s² * 0.1 s = 16.12 m/s or 58 km/h (36 mph).
Maybe there is a 50 Hz/60 Hz video on Youtube showing a good loop against backspin from a good angle to get a rough approximation of the real acceleration time and distance. There are some slow motion videos but I don't know which frame rate they used...

1) https://www.researchgate.net/public...ntrols/link/5ad8123eaca272fdaf803122/download found 273 ms for the visual reaction time. https://www.frontiersin.org/articles/10.3389/fnbeh.2019.00165/full found 232 ms for the visuomotor reaction time in "Thirty-seven young elite international table tennis players (18 male, 19 female, mean age: 13.5 years) from 23 nations..."

 

[Tinykin]

Interested in why you don't bend low. In my experience, LP players (not defenders) tend not to use high spin loops as a big part of their game.

"What is necessary is to have the ball pass over the net as low as possible because the ball will bounce up about 80% of it maximum height."
Depends on what the player is trying to achieve. Usually a loop as demonstrated is used against a high quality incoming ball. At normal human player level, we are simply trying to get the ball on the table. Higher ball is more consistent thus less skill required. Low ball is far more risky thus requires high skill.

 

[jk1980]

Isn't it also interesting that one of the best players actually showcases his topspin technique which goes against the general teaching consensus that you should NOT lean back while executing the stroke ?

We don't know if this video shows him looping a heavy backspin ball, but nonetheless this is settings a bad example considering the text book depiction of a loop.

 

[brokenball]

How fast? We can approximate that.From Kinematic Parameters of Topspin Forehand in Table Tennis and Their Inter- and Intra-Individual Variability https://www.jssm.org/volume19/iss1/cap/jssm-19-138.pdf we get "Studies related to the evaluation of kinematic and kinetic parameters of this stroke have demonstrated that at impact, the ball is hit by a racket moving forward and upwards at a resultant speed of approximately 20 m/s. The acceleration of the racket at the time of contact is approximately 180 m/s²..."
Lets say a push results in a ball going forward with 10 m/s and travels maybe 3 m before being hit = 300 ms.
Lets say Timo can react in 200 ms 1) 100 ms to accelerate -> 180 m/s² * 0.1 s = 18 m/s or 64.8 km/h or around 40 mph.
"The study examined seven top-ranked (international level) Polish adult male table tennis players" that were able to achieve 161.2 m/s² +- 4.6 in topspins against backspin 161.2 m/s² * 0.1 s = 16.12 m/s or 58 km/h (36 mph).
Maybe there is a 50 Hz/60 Hz video on Youtube showing a good loop against backspin from a good angle to get a rough approximation of the real acceleration time and distance. There are some slow motion videos but I don't know which frame rate they used...

1) https://www.researchgate.net/public...ntrols/link/5ad8123eaca272fdaf803122/download found 273 ms for the visual reaction time. https://www.frontiersin.org/articles/10.3389/fnbeh.2019.00165/full found 232 ms for the visuomotor reaction time in "Thirty-seven young elite international table tennis players (18 male, 19 female, mean age: 13.5 years) from 23 nations..."

Your articles are more about the player than the physics and optimization of the trajectory. The 180 mm/s^2 is interesting to me. I(we) tried measuring the acceleration using a cell phone app. We were able to saturate the accelerometer because its range limits was about 10g or 100m/s^2. The 40 m/s seems a little high but measuring the speed of the ball as it leaves the paddle is difficult because the ball speed decreases rapidly as a function of distance or time.

My issue with the article is that they said 40 m/s. No way is Timo Boll hitting the ball at 40 m/s in that video. If he did the ball would fly off the end of the table before gravity and Magnus effect could bring it down to hit the opponents side of the table. Since Timo Boll is hitting the ball up to get it over the net, he can't be hitting the ball that fast.

 

[brokenball]

Isn't it also interesting that one of the best players actually showcases his topspin technique which goes against the general teaching consensus that you should NOT lean back while executing the stroke ?

What is wrong with Timo Bolls' loop? In the end, it makes no difference how you move, it is only what is happening at the moment of contact.

We don't know if this video shows him looping a heavy backspin ball, but nonetheless this is settings a bad example considering the text book depiction of a loop.

I don't think these are back spin balls.
Here is an example of looping against a chopper. You can see that Henzel "waits for the ball". He doesn't always wait for the ball to drop but he consistently starts with the paddle behind his knee. The stroke is mostly upwards. The ball is not going 40 m/s. You can see the arc of his loops. Many of his strokes are just top spin drives when he hits the ball that is above net height.
https://www.youtube.com/watch?v=Dld67Quv0lg&t=162s

I am finding harder and harder to bend down like that.
What I am really interested is the trajectory of the loop.
There is a formula for calculating the acceleration when moving in a circle. a=v^2/r where a is acceleration, v is velocity and r is the radius. This formula can be rearranged to r = v^2/a. The shorter r is the tighter the arc is. The acceleration a is limited by gravity and the Magnus effect. v can start out relatively fast but you can see that if v is too fast, r will be big ( no or little ) arc and the ball may not even hit the table. During motion the velocity is always changing so it really should be v(t). The acceleration due to gravity is always down but the acceleration due to the Magnus effect is always pointing to the center of the arc which is always changing too.

My point is that there is an optimal spin to speed ratio and the velocity cannot be that high if you want to land the ball unless you have a light of sight flat hit or are relying of gravity to bring the ball down.

A lot of shots I see in user videos are simply relying on gravity.

 

[Dominikk85]

I think he is demonstrating a special variation of his loop to generate maximum spin. Here he is demonstration a more standard version of a loop

https://youtu.be/_AuDat6wb5Y

 

[brokenball]

Interested in why you don't bend low. In my experience, LP players (not defenders) tend not to use high spin loops as a big part of their game.

I am assuming you mean me since Timo bends his knees.
I get bored playing with the same thing all the time. Since I play for the exercise I change paddles a lot.
Lately I have been playing with my hard bat against inverted players.

Low ball is far more risky thus requires high skill.

Yes,Yes,Yes! Timo has that skill or should we say consistency. Timo risks having the ball hit the net. It is a risk reward trade off. We mere mortals would not have the consistency and would have more balls hit the net or fly long if we tried just clearing the net. This deserves another thread about control.

I want to talk about the optimizing the arc in a loop and getting the best spin to speed ratio. In another post I just made, I pointed out that I doubt Timo is looping the ball at 40 m/s because there would be no loop due to the flat trajectory.

Finally, I want to point out that too many are obsessed with speedy paddles an rubbers and I know it isn't optimal.

 

[Richie]

Isn't it also interesting that one of the best players actually showcases his topspin technique which goes against the general teaching consensus that you should NOT lean back while executing the stroke ?

We don't know if this video shows him looping a heavy backspin ball, but nonetheless this is settings a bad example considering the text book depiction of a loop.

I think this is a total myth. It's really contextual.

https://youtu.be/8nN-REA-fSE?t=84

How about in the video above which also shows the upperbody coming back on the BH vs push?

If you need to lift backspin, especially if it's heavy, you might need to go back a little for the added lift. But as you see in both videos they're plenty low to start with. In many situations you don't want to lean back because you're compromising your recovery. But against heavy backspin you have time to recover so it's not that big of an issue.

 

[tabletennisdaily1]

> I don't consider what most of you call a loop, a loop. It is just a ball with top spin.

What a dumb thing to say, you don't know what my technique looks like. I can assure you I know what a loop is, and I can also assure you that my loop is a real loop. I would also surmise that most people on TTD know what a real loop is, as opposed to this "ball with topspin" you talk of.

> I don't think it is necessary to get that low.

It is necessary to get that low for a high quality loop. As timo said, you need the legs to provide upward acceleration, you cant just rely on your arm. Also, you need the extra space to allow the blade to accelerate before ball contact to get high quality spin.

> It is to bad I can't see the ball land in the video.

There is one slow motion clip where you do see the ball land and the receiver hit the ball at 3:10.

 

[dingyibvs]

Isn't it also interesting that one of the best players actually showcases his topspin technique which goes against the general teaching consensus that you should NOT lean back while executing the stroke ?

We don't know if this video shows him looping a heavy backspin ball, but nonetheless this is settings a bad example considering the text book depiction of a loop.

He's clearly looping a heavy backspin ball, except for the one against MA Lin.

 

[IB66]

Sometimes, especially when TB steps across to a wide ball to his FH (more for a backspin ball) weight transfer during the stroke doesn’t transfer from his left leg to right, his right foot actually lifts off the floor!! Emphasis is transferring weight upwards, because that’s where his bat is going, because the face is more open to play v backspin and he is getting that ‘tangential’ movement sorted to optimise spin. Angle of racket, direction of movement of racket follows racket angle.

 

[VictorMoraga]

Almost a year since I 've been training with Coach Stellan.
And one of the main improvements I've been done is to bend my legs more. The quality of my loops are been improving consistently, especially for half-long serves.
Sometimes I make the mistake to stand after 2 or 3 loops "Working on that", because of too many years with the bad habit.
Don't try to bend the legs, Just Do It 😄 😉

 

[fzambetta]

Almost a year since I 've been training with Coach Stellan.
And one of the main improvements I've been done is to bend my legs more. The quality of my loops are being improving consistently, especially for half-long.
Sometimes I make the mistake to stand after 2 or 3 loops "Working in that", because too many years with the bad habit.
Don't try to bend the legs, Just Do It 😄 😉

I cannot agree with you enough! 😅

Same thing here: my coach has been working with me on this and not only has the quality of my loops improved dramatically but also my ability to recover.

Therefore, I have gone from being able to (hard) loop 1-2 balls in a row with consistency to 4-5 balls, at least.
Of course, that has a huge impact in a match situation, not just in training drills.
​​​

 

[Lazer]

I think this is a total myth. It's really contextual.

https://youtu.be/8nN-REA-fSE?t=84

How about in the video above which also shows the upperbody coming back on the BH vs push?

If you need to lift backspin, especially if it's heavy, you might need to go back a little for the added lift. But as you see in both videos they're plenty low to start with. In many situations you don't want to lean back because you're compromising your recovery. But against heavy backspin you have time to recover so it's not that big of an issue.

It makes a lot of difference, specially on FH. When you lean forward it automatically helps you with the right racket angle and swing. On top of this it is harder to bush the ball.

Cheers
L-zr

 

[Lazer]

> I don't consider what most of you call a loop, a loop. It is just a ball with top spin.

What a dumb thing to say, you don't know what my technique looks like. I can assure you I know what a loop is, and I can also assure you that my loop is a real loop. I would also surmise that most people on TTD know what a real loop is, as opposed to this "ball with topspin" you talk of.

> I don't think it is necessary to get that low.

It is necessary to get that low for a high quality loop. As timo said, you need the legs to provide upward acceleration, you cant just rely on your arm. Also, you need the extra space to allow the blade to accelerate before ball contact to get high quality spin.

> It is to bad I can't see the ball land in the video.

There is one slow motion clip where you do see the ball land and the receiver hit the ball at 3:10.

Couldn’t agree with you more. I wouldn’t call anything other than a brush for a loop, most “loops” I call topspin drives…

Cheers
L-zr

 

[dingyibvs]

I think this is a total myth. It's really contextual.

https://youtu.be/8nN-REA-fSE?t=84

How about in the video above which also shows the upperbody coming back on the BH vs push?

If you need to lift backspin, especially if it's heavy, you might need to go back a little for the added lift. But as you see in both videos they're plenty low to start with. In many situations you don't want to lean back because you're compromising your recovery. But against heavy backspin you have time to recover so it's not that big of an issue.

No technique is absolute. I've been watching a lot of Chinese instructional videos lately, most by former CNT players/coaches, and a lot of them contradict each other. For example, Yin Hang teaches BH loop driving backspin by starting the swing from near the left thigh, while Fang Bo and Harimoto's coach advocate starting from the left hip. There were disagreements between FB and a CNT 2nd team guy on how to do a short push and whether to use a longer or shorter swing swing for BH driving backspin.

Like you said, I think it's all contextual. Different situations call for different techniques. For example, YH is assuming that you're dealing with a very low and fast push that you can only reach at the mid-falling stage, while the CNT 2nd team guy assumes that you're leaning into the table expecting a short ball so you don't have time for a big swing.

 

[brokenball]

> I don't consider what most of you call a loop, a loop. It is just a ball with top spin.

What a dumb thing to say, you don't know what my technique looks like. I can assure you I know what a loop is, and I can also assure you that my loop is a real loop. I would also surmise that most people on TTD know what a real loop is, as opposed to this "ball with topspin" you talk of.

Now we are getting to the heart of the matter. What is the definition of a loop. Is any boll with top spin a loop? I don't think so. Is an ball that is hit when there is a light of sight trajectory a loop? I don't think so.

If you know what a loop is then tell us. The Chinese call a loop "la qiu" which means pull ball. Basically they mean dragging the ball over the net with the friction of the rubber while brushing.

> I don't think it is necessary to get that low.

It is necessary to get that low for a high quality loop. As timo said, you need the legs to provide upward acceleration, you cant just rely on your arm. Also, you need the extra space to allow the blade to accelerate before ball contact to get high quality spin.
[/quote}
I agree if you want a top grade loop but in the end it doesn't matter what the body does. It is what the paddle is doing when it hits the ball. The end result should be an arc which has a much tighter radius that one due to gravity alone.

So far, everyone has ignored this.

 

[brokenball]

Couldn’t agree with you more. I wouldn’t call anything other than a brush for a loop, most “loops” I call topspin drives…

Cheers
L-zr

I am agreeing with Lazer here.

Also, no one has address the radius of the arc of the loop yet. r=v^2/a.
It is clear that velocity has much more effect on the radius of the loop than the acceleration due to gravity or the Magnus effect.

Why is everyone ignoring this?