Interactive Forum: Extension

[crosscourt]

I would be interested to know where John, Brian and Jeff think the power in different types of shots come from. Concentrating on groundstrokes the most likely contenders seem to me to be the legs/leg drive, back and shoulders/torso rotation and arm.

Any views?

cc

[BrianGordon]

I would be interested to know where John, Brian and Jeff think the power in different types of shots come from. Concentrating on groundstrokes the most likely contenders seem to me to be the legs/leg drive, back and shoulders/torso rotation and arm.

Any views?

cc

Pretty loaded question (so to speak). I’m sure John and Jeff bring a different perspective to the table than myself. I’ll only say if they can answer that question in the terms of my perspective, they will be receiving the Nobel prize in Science next year. All of the candidates you mention are involved (of course you did not leave much out). Following are things we KNOW:

1. Shot “power” is function of ONE thing (disregarding impact dynamics), racquet speed at contact.

2. Racquet speed at contact is a function of ONLY two things – the torques and forces applied to the racquet by the hand.

3. Racquet speed is linked to (not caused by) joint and segment rotations of the candidates you mention in a way we can define with reasonable certainty.

And that’s about it. Until the following things are understood, we basically know nothing (although some more nothing than others):

1. Exactly how the hand forces and torques (on the racquet) are organized to produce penultimate racquet speed.

2. How other joint actions (forces and torques) impact the hand effects in the general case.

3. How different positional approaches alter these interactions.

My two cents is that I can’t answer your question with anything other than qualitative speculation based on logic, experience, and the pieces of the puzzle I have in place (which is a pretty compelling story, but still just a story) – I’m working on filling in the rest of the puzzle as we speak. So- while I can answer to specific issues, like why a straight arm is good or bad for example, and unless I’ve overestimated the global depth of your last question, I’ll have to defer until a later date – have at it boys.

P.S. – Jeff – did you receive the private message I sent.

[lukman41985]

So- while I can answer to specific issues, like why a straight arm is good or bad for example, and unless I’ve overestimated the global depth of your last question, I’ll have to defer until a later date – have at it boys.

Why is a straight arm good or bad?

[johnyandell]

Brian,

That is as succinct a sumation of the known and unknown I have ever read. Got time to edit some articles? Just kidding. I hope you and Jeff will cook up something good.

John

[BrianGordon]

Why is a straight arm good or bad?

Mechanically speaking - the straight arm has advantages and disadvantages - choice is based on individual attributes as I've mentioned. I believe I've given ample clues, at least in terms of direction to channel thinking, for participants to decide for themselves - which is how I will be participating in this forum when time allows in the future (and which just expired for the near term) - good luck, happy holidays, and I look forward to seeing the interesting discussions in 2007 - Brian

[federer]

It seems that Federer's forehand is utilizing the basic principal of a forehand volley. It you take away the unit turn, and hold the racket with a laid back wrist + semi western grip. It's exactly like a forehand volley. Instead of using muscle to maintain a structure, the skeletal structure is used to provide support.

Any anaylsis of Justine's new forehand? It seems that she upgraded her forehand!

[lukman41985]

Instead of using muscle to maintain a structure, the skeletal structure is used to provide support.

Could you explain this further, please? I don't understand what you mean by this. Thanks in advance.

[federer]

The double bend has a bend at the elbow which is maintained by the triceps and biceps. A straight arm doesn't use as much muscle power to maintain the structure. Federer's straight arm forehand is similar to the state of you legs when you are standing straight up. A double bend will be more like in a squatting position. Standing straight up utilize the skeletal structure, thus preserve more energy vs the squatting position. Similar, hitting with straight arm preserve more energy vs the double bend.

[lukman41985]

Thanks for the clarification. The straight arm forehand definitely feels more free-flowing (i.e. requiring less use of the muscles that go into maintaining the double bend).

[jeffreycounts]

I would be interested to know where John, Brian and Jeff think the power in different types of shots come from. Concentrating on groundstrokes the most likely contenders seem to me to be the legs/leg drive, back and shoulders/torso rotation and arm.

Any views?

cc

What I find interesting is, as I talk about in my articles, the structure of top forehands. When I first looked at video years ago, I expected to see the tip of the racket come across the body, like in a baseball swing, because this circular path would generate the most racket head speed.

However, what I saw (and still see) is the tip of the racket stay back through impact. The tip of the racket never comes across the body like it does in a baseball swing. Instead the tip of the racket stays back and goes up and around in a rainbow path. And on contact, as you can see in the Hewitt picture, the racket never gets "ahead" of the body. The double bend assures this. In the Haas picture, way after contact, the double bend is fully intact. Why wouldn't the tip of the racket have shot across the body, if he was trying to maximize racket head speed?

So I agree that racket head speed would be the obvious factor of shot power, but I wonder why we see the arm, hand, and racket in a "double bend" formation on contact, rather than the racket head accelerating more independently of the body, where it could pick up even more speed?

My conclusion is that there has to be some tremendous value in a proper supporting structure behind the racket on contact. Hitting the ball squarely in the sweet spot, with the body properly behind the racket, must account for something.

So my conclusion would be that maximizing racket head speed is a fine goal, but it must be maximized within a double bend structure (Federer and Nadal are another story).

[lukman41985]

To add to Jeff's points/visuals, here's a picture of Paradorn:

[crosscourt]

I wonder about the view that says it is racket head speed that is the source of power. Isn't it the force applied to the ball that dictates the power of the shot? Racket head speed may be an aspect of this, but most likely only an aspect.

[johnyandell]

According to Rod Cross (Technical Tennis) it's the speed of the racket. It's a great book that explains the physics in simple English.

[crosscourt]

I have a copy. What would you rather be hit by, a truck travelling at 75mph or a feather travelling at 100mph?

[johnyandell]

Read the book.