Dwell time

[ttpshot]

That video which shows in many ways how Marcos Freitas is able to do magic tricks with the racket and the ball as a result of his touch is pretty fun to watch.

But I think this one is worth posting as well.



In the pull ball in Suga D's video, you can kind of see how, as a result of the players touch, the ball does stay on longer than a normal shot.

The difference between .5 miliseconds and 1 millisecond is 100%. I would say that the dwell time on that pull ball is several times longer than the dwell time of a flat hit.

So, if someone is trying to say that dwell time is always the same regardless of what you do, I am going to say that is inaccurate. And the kind of racket you use, particularly the kind of wood, can make it easier or harder to hold the ball on the racket surface for more or less time.

So yes, there are different dwell times, not just feeling. And even if we are still dealing with ridiculously small amounts of time, a slight increase means a lot in terms of letting the rubber deform and rebound while the ball is on the surface of the rubber. Again, the difference between .5 milliseconds and 1 millisecond is a 100% time difference. And .5 milliseconds is the number Pnatchtwey kept repeating. And I would be willing to bet that the dwell time difference in that pull ball is a greater difference that .5 milliseconds to 1 millisecond.

It is clear that dwell time is not always the same.


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But what is the difference in dwell time between a flat hit and a loop? We all aim to increase the dwell time to spin the ball harder but could it be that the sensation of the dwell is caused by us brushing the ball(as opposed to flat hit) which means less vibration.

 

[ttpshot]

Actually, to elaborate on this, we have structures in our skin that are specialized for detecting changing and short stimuli, known as Pacinian corpuscles and Meisner's corpuscles. In normal life, these things help us detect textures when we rub our hand over a surface (or when we make stone tools by chipping one stone against another). They are adapted for short and rapidly changing stimuli. But even those guys are not going to respond to a 1 millisecond stimulus. Bear in mind too, that these cells fire an action potential when stimulated above their threshold, but the action potential itself will last longer than the dwell time of any racket/rubber combination. However, they must respond to the buzz of vibrations in the whole blade that occur when the ball strikes the blade because we can certainly feel that.

I share the OP's wonder that these different blades and rubbers feel as different as they do. It is quite remarkable, whether it has anything to do with dwell or not. When you know more about the underlying physiology it becomes even more amazing, not less!!!! I honestly have no idea how we are able to do this.

That's a wonderful insight on the subject. If we physicaly cannot detect the dwell time what is the factor(s) that give us the illusion of dwell? Is it the vibration mode? Sound? Or the trajectry of the loop? Because, if we know exactly what they are, a blade/rubber can be build with less dwell time but gives the impression of more dwell and vice versa.

Some TT makers has build an all carbon blade has for R&D and it's reported to have absolutely no dwell feeling yet the ball spins just as much as wooden one. With ITTF moving towards abolishing the wooden composition of the blade, I'm excited to see how it'll change my view on blade dwell completely.

 

[ttpshot]

I think touch in serves and receives are different.

In serves and loops, you'd want to hit the ball thinly. But in receives, it's more of reading the spin and presenting racket angle accordingly.

 

[Baal]

An intersting experiment to try. I haven't done it yet. Put on some leather gloves and see how you play. Deaden the feeling. Lose "touch". What happens?

My prediction is you will play ok. You will still have vision and proprioception, the two most important TT sensations. Sound too.

But maybe if you did it for weeks your game would decline?? I'm not going to try that. But maybe touch helps train you by reinforcing your other senses, by providing feedback?

 

[ttpshot]

An intersting experiment to try. I haven't done it yet. Put on some leather gloves and see how you play. Deaden the feeling. Lose "touch". What happens?

My prediction is you will play ok. You will still have vision and proprioception, the two most important TT sensations. Sound too.

But maybe if you did it for weeks your game would decline?? I'm not going to try that. But maybe touch helps train you by reinforcing your other senses, by providing feedback?

That, I have always wondered too.
Butterfly sells a chanky racket for shadow swing that weighs 400~500g. A racket that heavy and thick had absolutely no vibration felt and it was very hard to control when I put on an old rubber and had a hit with it.

When we choose the equipment for beginers, we usualy recomend 5 ply all wood with not so fast rubber with 1.8mm sponge to allow for more feedback. Then we slowly progress to harder materials for both rubber and blade when we know that he/she hits hard enough to have the feedback.

Carbon blades have been pushed aside by other composite materials as it had less feed back so as you said, good vibration(when the ball hits the sweet spot) could well be a key to improving and developing a correct strokes.

 

[Archosaurus]

Baal, I don't think playing with gloves would negatively influence someone's touch. It would probably increase their touch, and also their other sense.

In his Ultimate Speed Secrets book, for race car drivers, Ross Bentley talked about restricting some of your senses ie: feel, hearing etc. (Vision is generally not very safe to decrease when talking about race cars) to increase their sensitivity.

He found that driving with thick gloves on improved a driver's physical touch once they took the gloves off, and doing something like heavily restricting hearing amplified other senses like vision.

Feel when driving a race car is much so like feel in table tennis, and it follows some same principles, because we're dealing with vibrations and whatnot. With this in mind, I think that playing with thick gloves on would probably improve someone's touch once they took them off after playing with them for some time.

 

[Baal]

Nonsense, Arch!!

Gloves add a mechanically compliant layer between the mechanoreceptors in the skin on your fingers and palm and the wood on the blade (or anything else you try to touch). This would reduce the ability to detect certain frequencies of vibrations. You can convince yourself by simply touching a vibrating object while wearing gloves. It won't feel the same, especially if the vibrations are not real strong. This is not eve a matter for debate, it is mechanics. How much and at what frequencies would depend on the gloves. It is the same reason that bubble wrap protects stuff in packages that you mail. Don't make simple stuff complex.

 

[Ilia Minkin]

Nonsense, Arch!!

Gloves add a mechanically compliant layer between the mechanoreceptors in the skin on your fingers and palm and the wood on the blade (or anything else you try to touch). This would reduce the ability to detect certain frequencies of vibrations. You can convince yourself by simply touching a vibrating object while wearing gloves. It won't feel the same, especially if the vibrations are not real strong. This is not eve a matter for debate, it is mechanics. How much and at what frequencies would depend on the gloves. It is the same reason that bubble wrap protects stuff in packages that you mail. Don't make simple stuff complex.

A few pros use overgrip and do pretty well. Not sure if overgrip are comparable to gloves.

 

[Archosaurus]

It's possible that the amount of vibrations is simply not enough in table tennis to produce needed feedback, but let me entertain you with something:

When you feel something, you are receiving input and your brain actually produces the feeling. Better players have better brains more so than better receptors, right?

When you restrict input, and ask for more output from the brain for less input, you can train that sense. This is true for sight, absolutely true for sight, but I'm not sure if it's true for feeling, or other senses.

It's true that some frequencies of vibrations will be dampened and you'd be fooling yourself if you said you can feel them with gloves on, but the purpose is to restrict input for a better output. Not to become more sensitive in sensing those frequencies that you simply can't with gloves on.

 

[Baal]

A few pros use overgrip and do pretty well. Not sure if overgrip are comparable to gloves.

Yes. Very good point. I had meant to mention it. Samsonov for one uses an overgrip. Here in the US Jim Butler*.

For sure, it is a bit like gloves. I once used the stuff myself. It didn't affect my touch.

And again, make no mistake about it, putting any soft compliant layer between the wood and the skin affects the way you will sense vibrations coming though the handle. It will act a bit like a "low pass filter", so higher frequency components will not be felt the same way or at all. Of course, the forefinger will still be on the top of the blade. With gloves even that is covered.

So what this tends to make me think is that these particular parts of our sensory apparatus (vibration sense in the skin of our palms and figers) are not very important for high level play, for generating spin or serving or returning serve.

So I come back to what NL posted. A lot of it is seeing what is happening with the ball (hence some things can be improved with a computer app). And then being able to execute the appropriate response (which requires balance and proprioception).

I think in other words, "touch" and "feel" are words we use to describe something in table tennis that is very real, but is not actually quite the same thing as touching or feeling something with your fingers, or even that much with your hands (except maybe how tight you grip and the racket angle).

I think the words we use may be misleading us quite a bit about what is really happening.

* What is funny is that Jim Butler started using an overgrip because of me. When he last came out of retirement a few years ago, he looked at my blade which at the time had an overgrip and asked how the hell I could play with something like that since wouldn't that cause me to lose all feel? Here in Houston, the environment is ridiculously humid, so hand sweat is a huge problem, especially in summer when our AC systems don't really keep up with 100 degree heat. So he tried my blade, and really liked it, saw that it was no problem to make shots, and has used it ever since. In his previous playing career, he had never used one. Funny thing is I stopped using it. I found it made it harder to switch my grip from FH to BH because the think got sticky.

 

[Baal]

When you feel something, you are receiving input and your brain actually produces the feeling. Better players have better brains more so than better receptors, right?

When you restrict input, and ask for more output from the brain for less input, you can train that sense. This is true for sight, absolutely true for sight, but I'm not sure if it's true for feeling, or other senses.

Actually this is a pretty interesting point. It is true. But what I am saying is that our brains ultimately integrate a huge number of inputs, and try to filter out distractions that make it harder to complete the task. And it is can be quite difficult to actually break down the contribution of each sense without actually taking steps to remove that part of the stimulus. There is an entire field of cognitive science/sensory physiology called psychophysics where that is pretty much the main experimental strategy. The results can be really surprising. Visual pychophysicists can learn a lot about how brain processes visual information from visual illusions, and then can invent new illusions to prove their ideas. When many senses are involved, things get incredibly complex.

The use of a glove or overgrip could be a really simple way of assessing the contribution of vibration mechanoreceptors in fingers and palms, which is the thing people tend to focus on when they discuss "touch and feel" in table tennis.

 

[Archosaurus]

Baal, do you see anything with my thinking above?

You mentioned it yourself, but feel is a lot more than just physical feeling. Feel is being able to produce the wanted result on the ball, right?

So my reasoning is that with restricted physical feeling, one can get more out of very little input to produce a better concrete output ie: a more desirable ball that meets expectations better. Then when you take the gloves off, and the feedback is as unrestricted as it was before, you can produce the same ball or better easier.

Is this wrong?

EDIT: Nice timing.

 

[Baal]

Try hitting some balls with gloves and see if you play better. Only way to test your idea.

 

[Archosaurus]

I could, and I think I will. However I'm somewhat sure I will run into placebo.

My level is simply too low to produce accurate empiric results. Everyday I improve a little.

If I play this week mostly with gloves, and take them off the next week, and I've improved, what conclusion do I come to?

 

[NextLevel]

When I play with overgrip, I know that a significant part of my hand, especially my index finger and thumb, is located on the blade face. Others may differ, but I find that I often don't wrap the higher parts of my blade closest to the rubber with overgrip in order to get some wood sensation. I also notice that my grip is a little tighter when I use overgrip, partly because the softness lets me do that.

 

[UpSideDownCarl]

First, let's see if I can translate Archie into English.

I think he is saying that by using the glove and thereby depriving your hand of feeling for a time, that after, when you take the glove off, you would be more sensitive to feeling the sensations from the blade.

Is that right Archie?

Now, I am going to agree with Baal that this is foolish and there is no need to over complicate things with theories.

Even if it worked, and, for a short time you were able to feel more, you spent how ever long you spent not feeling as much because the gloves blocked your feeling. And in race car driving, while you do test runs, you wouldn't be harming the technique and precision of how you steer as a result of the sensory deprivation. But in TT feeling less when you need to develop that touch would harm the development of refined contact.

And the extra feeling would be short lived. After a few hours of play the increased feeling from taking the gloves off would be gone. So the experiment would not hold any long term benefit. And the biggest thing you would be left with would be the time you wasted with the gloves on.

This is also why I would not want a grip on my handle.


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[Archosaurus]

No, Carl. You would feel less. However you could train your brain to "make more sense" of less input. Does that make sense?

 

[UpSideDownCarl]

No, Carl. You would feel less. However you could train your brain to "make more sense" of less input. Does that make sense?

Well, if that is what you are talking about then I say, go back to drinking that Kool-Aid. Because that is totally idiotic.


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[Archosaurus]

Well, if that is what you are talking about then I say, go back to using the drugs. Because that is totally idiotic.


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Explain.

I know that when you ask for more output from your hearing or your vision for example, you can train your brain to produce a more accurate, or should I say more desirable output. If you restrict the sense, you can train your brain to produce good output with less input.

People's vision, hearing and feeling does not always produce accurate results. They can be trained. Worse players or worse drivers very much so don't see, hear and feel the same things as better players or drivers.

What part of this is idiotic?

 

[UpSideDownCarl]

As far as the stuff Baal is actually talking about, he has been presenting some pretty cool information about how our sense of feeling works and how, what we feel in our hand can't accurately represent what is happening as the ball is on the surface of the blade face.

I think it is pretty cool and I am going to have to accept the fact that what we feel may not be an actual and accurate representation of what is happening while the ball is in contact with the blade face.

And what is happening, I am okay with not being sure of exactly what it is.

But that feeling where it feels like you hold the ball on the rubber longer and it feels like the rubber stretches and distorts, and it feels like the topsheet grabs the ball, when you do that, when you feel that, whatever is happening when you feel that, that causes a loop to get more spin. And that art of touching the ball delicately with power while pulling past the ball, it is easier to develop that with a blade that helps you feel more.

You can still develop it with a blade that blocks some of that feeling in your hand. But, it is harder and you need to be pointed in the direction of feeling it to more of an extent.

So, Archie, based on your theory, I say you order yourself a Timo Boll T5000. That would be like wearing the glove and even more.

In fact, why not play with the T5000 and gloves and whatever rubbers make it hardest to feel. Maybe you could play blindfolded with earplugs to make you see and hear better.

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