ETI 049 | Racquet Rebound Potential – you will be surprised

A racquet hangs from a rope or is balanced on the butt cap

A ball machine shoots a ball at the racquet and the rebound velocity is “x”

Now the racquet is fastened in a vise so it cannot move.

The ball machine shoots again and the rebound velocity is again (nearly) “X”

We might be able to hold the racquet looser than anyone would ever believe.

37 Comments

  • Russell Lawrence

    Reply Reply January 3, 2017

    Happy new year to you
    This is a tricky one, hence my slow reply while the festive booze clears.
    In the thread “does ball or racket speed determine return velocity”, that’s easy, its the closing velocity of the two that matters.
    The rebound from an unsupported racket is trickier. I am certain the racket weight is important, and a very light unsupported racket would return the ball slower.The reason must be because a racket is like an elastic catapult and slack strings give higher ball speed. Infinitely tight strings are like a paving stone with lower return ball speed. However you then get better directional control, when, as a number of players often do, miss the sweet spot. The other benefit to ball speed of a slack grip is the whiplash effect of the racket head, but again with a risk of misdirection.
    BUT, what use is physics when you play outdoors in windy & wet conditions !!

  • Fred

    Reply Reply January 1, 2017

    The issue is transfer of momentum: think of the desk toy with six balls suspended on strings- when the ball on the end string is lifted and released to swing into the other five, the four in the middle remain motionless while the ball on the opposite end swings forward. The issue is the amount of energy redirected – while in contact with the ball. Think about the example of hitting a serve – it is the racquet velocity, not arm strength or death grip that produces velocity. The looseness of the grip provides maximum velocity. For illustration, the Sampras three finger service grip and forearm rotation serves primarily to “free” the wrist, IMHO.

    • Jim McLennan

      Reply Reply January 1, 2017

      Fred – thanks for the note – and yes, though perhaps hard to prove, looseness will improve the ability to accelerate the racquet – and with a mentor Fred Earle who helped me on understanding the serve, Fred said, “Pete has (had) the most relaxed motion I have ever seen.” Relaxed = loose = effortless tennis.

    • Francisco

      Reply Reply January 2, 2017

      Would Pete Sampras hit a three fingers volley? Probably not.

      • Jim McLennan

        Reply Reply January 2, 2017

        Francisco – for sure, and I have been thinking of this – for the serve the looseness and relaxation are the key – for the volley there is the opposite a “wall to the ball” where grip tightness at contact is very important – but note many are tight throughout the preparation and that actually slows and stiffens the arm as the racquet is moved into hitting position
        Jim

  • Major Dan

    Reply Reply December 31, 2016

    It is not easy to allow myself to hold the racquet so loosely but when I do, I think I experience what you are talking aobut.

    It does require hitting the ball in the sweet spot – off-center hits are a disaster with a loose grip.

    • Jim McLennan

      Reply Reply January 1, 2017

      Major Dan – it is not easy for any of us to always relax when playing – so you are not alone – but truly off center hits are not much better with an overly tight grip
      Jim

  • Jeff, New Jersey

    Reply Reply December 31, 2016

    Jim – very interesting but, discusses only a single source of “force” the incoming ball and a stationary racquet.

    In a sense a serve is the same but opposite, stationary ball, incoming racquet. And we’ve all be told to have a loose grip to facilitate wrist snap or perhaps better stated as pronation which helps generate power.

    What happens on ground strokes where there are two opposing forces, incoming ball and oncoming racquet (and its path that can develop multiple forces like up and forward)? And what’s the effect of each forces relative speed to the other? Faster ball v slower racquet or visa versa?

    We’ve all seen pictures of a ball squashed against the string bed of pro players racquet… hard to translate the points made in your video.

    Help Coach!

    • Jim McLennan

      Reply Reply January 1, 2017

      Jeff – I am not sure I can explain then there are two opposing forces – I was just trying to provoke a discussion as well as thought about the nature of the grip – and how varying grips may change a players “feel” for the game
      Jim

  • skip purinton

    Reply Reply December 30, 2016

    Like Gary, I’m puzzled by the seeming contradiction with the drop volley

  • Shmuel Goldberg

    Reply Reply December 30, 2016

    It is still good to keep the grip tight for precision.
    The effect that you have mentioned allows us to keep the wrist joint flexible, so that the hand with the racket, the last section of the kinetic chain, gets the maximum of the angular momentum generated in the stroke. (Actually, the speed of the ball.)
    A relaxed grip would separate the racket from the palm of he hand and make the racket the last section of the kinetic chain. We might gain more speed, but the cost is precision.

    • Jim McLennan

      Reply Reply January 1, 2017

      Schmuel – maybe – the game is about the balance between speed and precision – and often to reduce errors it is about the precision more than the speed – that said I am not sure that a loose grip will inhibit precision as that depends on level of skill, influence of the incoming ball whether difficult or simple, and what one wants to do with the ball – Jim

  • Joe Lombardi

    Reply Reply December 29, 2016

    When I’m playing poorly, there can be numerous reasons, but the two most common — which often occur simultaneously — are 1) having a death grip on the racket and 2) not finishing/following through. I think the the second is a symptom of the first. When I relax my grip, my whole body tends to relax, my motion is more fluid, I finish properly, and I generate “effortless power.”

  • Francisco Barahona

    Reply Reply December 29, 2016

    Put a racket on the floor and drop a ball on it. Then put your foot on the handle and drop a ball again from the same height. You will see that the bounce is totally different. That makes me disagree with those scientists.
    🙂

    • Dan

      Reply Reply December 30, 2016

      Not the same concept. Contact points are different, and the inertial references are changed.

      I can conceptually agree with rebound velocities but there are more things at play when accelerating the racket to impact speed. It’s not passive, so grip does matter.

      A side comment is to all of those people that describe serves or spin as rolling the racquet and pushing off the ball during the stroke- any YouTube demo of the kick serve suffices- are off base because the ball is off the strings before you feel and flick.

    • Jim McLennan

      Reply Reply January 1, 2017

      Francisco – I have done the same experiment with the same results (with the foot on the floor) but still this article was about asking players to experiment with looser grips – send me something of your game and let me take a look
      best
      Jim

      • Francisco

        Reply Reply January 2, 2017

        I agree that a loose grip leads to a better swing. On the other hand a volley with a tighter grip should be deeper than the same volley with a loose grip. So should we start the swing with a loose grip and squeeze at contact? It might be hard to coordinate :-/

        • Jim McLennan

          Reply Reply January 2, 2017

          Absolutely – but the key in the timing is to squeeze at contact
          Jim

  • Jerry winder

    Reply Reply December 29, 2016

    Jim,
    Always like your stuff!inthis case, right or wrong, havealways leaned to softer grip to help my power. Time will tell, huh!
    Best of 2017!…JW

    • Jim McLennan

      Reply Reply December 29, 2016

      Jerry – I hope others see your comment – for truly the secret is (as you describe) a “softer grip”
      best
      Jim

  • Michel

    Reply Reply December 29, 2016

    Absolutely love your scientific approach and insite to the game of tennis.

  • Katherine

    Reply Reply December 29, 2016

    Interesting conclusion. Good reminder to share with our Junior players and those at a lower NTRP rating. Thank you for sharing Jim!

    • Jim McLennan

      Reply Reply January 1, 2017

      Katherine – thanks for the note – and for sure you are welcome!
      Jim

  • Kevin Bryant

    Reply Reply December 29, 2016

    12 minute mark of this one: https://www.youtube.com/watch?v=zwoINjV20BM

    How does that figure in with your conclusion from the experiment?

    kb

    • Jim McLennan

      Reply Reply December 29, 2016

      Kevin – the suspicion is that a tighter grip also tightens the arm and even the shoulder such that tight players do now swing as easily or as accurately – not proven but that is what I think
      Jim

  • Ry Adams

    Reply Reply December 29, 2016

    So what would be the benefit of the looser grip in comparison?

    In the other direction, does it imply that people with a vice-like grip on the racquet are not being disadvantaged as much as supposed?

    • Jim McLennan

      Reply Reply December 29, 2016

      Ry – just the idea that perhaps a loose grip will work better than some would suspect – and when looser the swing itself may become looser and hopefully better – way too many people play a “tight” version of our game
      best
      Jim

      • Kwok

        Reply Reply December 29, 2016

        I started using a loose grip a few years ago – mainly with 2 fingers while the other fingers slightly touching the handle for support, but I firm up the grip a little more at impact with the ball for better control. I’ve been liking it so much that I never use any other way to hold the racket. With this same way of gripping the racket, I can hit volleys with ease most of the time. Also I use the same grip to hit my serves. The interesting thing is I seldom injure my wrist or arm or get a tennis elbow.
        People who never use a loose grip should give it a try. If all possible, hit the ball out in front. You may like it.

        Kwok

        • Jim McLennan

          Reply Reply January 1, 2017

          Kwok – thanks for the note old friend – if ever up in the SF Bay Area drop by the club
          Jim

          • Kwok

            January 8, 2017

            Jim,
            Are you going to Indian Wells this year ? If you are, what date ? Is there any place up there where you can give me a couple hours of lessons ?

            Kwok.

  • Al Cenci

    Reply Reply December 29, 2016

    As a retired tennis varsity coach, I am still asked,”should I string tighter for more pace or, looser for more control? In my view, they’ve got it backwards: the potential energy is in the string tension, the kinetic energy is released after the ball strikes the racket strings and is transferred to the ball. The tighter the string tension, the more resistance to allowing that transfer that is “stored in the stringing” And lets not forget frame composition and swing speed.

    I know, it’s complicated.

    • Kevin Bryant

      Reply Reply December 29, 2016

      Makes sense to me, as a volley with no swing and a tight grip doesn’t go anywhere, either. . .

  • Gary Hawkes

    Reply Reply December 29, 2016

    I agree that you want a relaxed grip on ground strokes but I thought that was to facilitate racquet head speed and to aid in keeping the racquet on target through the hitting zone. The finding you discuss is surprising, yet seems to me to be somewhat contradicted by the experience of a drop volley made by loosening your grip to take the pace off the ball. I know that hitting the drop volley also requires a cradling or catching action to take the pace off, but I thought that loosening your grip also had a significant effect. Now I’m a bit puzzled…

    • Geoff R

      Reply Reply December 30, 2016

      While the experiment demonstrates the principle, it does not duplicate the real world action of a tennis stroke, where the racket is moving. Most of the apparent contradictions with experience (drop volley, etc) dissolve when you add in the MOVEMENT of the racket ie. racket head speed, angle of contact, amount of brushing/spin, etc. Thus even though you can generate the same velocity with a loose vs firm grip, you apply lots of different types of mojo to the contact with the ball to make it do what you desire. My tennis pro (former ATP pro) had me pull the racket out of his hand at the end of his BIG forehand, and it slid out effortlessly! Remember that your grip is primarily a function of the muscles in your forearm, not your hand, thus Jim’s point about a light grip loosening up the entire kinetic chain seems logical. I know when I remind myself to lightn my grip, all my shots improve.

      • Jim McLennan

        Reply Reply January 1, 2017

        Geoff – thanks for the note about your pro and his grip on the forehand – we have a pro at our club who plays similarly! (PMac)
        Jim

  • Martin Hassner

    Reply Reply December 29, 2016

    And as usual you have recognized the “something”. I regularly play with a golfer…he loves the sport more than anything but plays tennis because he is a ferocious competitor and likes to test himself every weekend to compete with his desire vs my Tennis expertise. The key moments of our game often rest on the six or eight shots in a set when I drive him deep into his backhand side, running away from me, back to the net and simply gets his racket on the ball which is already behind him with no obvious forward motion. And the ball comes back…simply a rebound on the racket.

    Physics indeed …we all know that when we really hold that racket loosely…once or twice a month…we get the best shots we can make with little or no effort.

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