Whipping action on the serve...

[gzhpcu]

Whipping action comes in the kinetic chain when one element abruptly stops, transferring speed to the next element. To get the maximun whipping action on the serve, aim the arm up at ball, as it causes the wrist and racket to get maximum velocity. As the arm slows down, the wrist whips forward, when the wrist slows down at impact, the weight of the racquet is then forced downward.

If you aim forward, you are shifting your maximum to a point after impact and end up muscling the ball at impact, instead of whipping it. Instead you should aim up at the ball. An indication that this has been done correctly is therefore the racket head pointing downwards after impact. (the pronation is automatic)



Please let me know if this reasoning is correct John. Thanks!

[lukman41985]

Interesting observations, Phil. But the idea of aiming for the ball seems to go against the notion of hitting through the ball. Seems to me you want to accelerate through the ball and that in terms of teaching and executing for oneself, it's a better thought to hit through the ball than at the ball. The result will be more extension--and as a by product, I would think more power and accuracy. That's just my opinion though. Maybe Brain Gordon or Greg Ryan will be able to jump in here!?!?

[GregRyan]

Whipping?

I really don't like the word "whip" when referring to tennis strokes. I understand the analogy; both a whip and a stroke generate force at the end point of a kinetic chain. The difference is the human body is basically made up of body segments that are rigid and a whip is one continuous, flexible segment. The "whipping action" that is being discussed is a product of a kinetic chain where maximal racquet head speed is produced by the timing of acceleration and deceleration of body segments.

When one discussed the kinetic chain the specific segments of the body must be addressed. I have no idea what "aim the arm at the ball, as it causes the wrist and racquet to get maximal velocity' is referring to. Aiming is a thought process and not a muscular action so I don't understand what this has to do with racquet head speed. There are two segments to the "arm" (upper and lower) so once again I am not sure what is being discussed here.

It is true that when one segment decelerates energy is transferred to the next segment in the kinetic chain, but this is a simplification of what is really happening during force production of the stoke.

Our high speed research has shown that the wrist flexes from an extended position to a neutral position during the upswing and never snaps (flexes past neutral) before ball contact. For most pros the wrist never flexes past neutral even after ball contact. Take a look at some serve clips and look at the wrist positions when the racquet is parallel to the ground on the way up, ball contact, and racquet parallel to the ground on the way down. The wrist does not go into a flexed position; it stays neutral after contact as the forearm pronates.

The racquet must come down because the elbow is extended at contact and it can not move in the vertical direction unless you release the grip. The arm naturally decelerates by using muscular force of the shoulder and elbow joints; this has nothing to do with the wrist. Pete’s racquet points to the ground midway down because of elbow flexion and shoulder extension. Federer primarily uses the shoulder joint to decelerate because his elbow remains extended through the deceleration phase. His racquet points to the ground because his arm is pointed to the ground.

I do not think pronation is automatic but I do think the wrist action could be automatic. From the racquet drop position the elbow extends forcefully and causes the wrist to bend back if the muscles are relaxed. This is what causes the wrist to be placed into extension (creating more range of motion) and places the flexor muscles of the forearm on stretch (A stretched muscle is more powerful than at normal length). Also, when a muscle is stretched it automatically contracts as a reflex mechanism. This is what I feel the “whipping” action is that is being discussed.

I feel (with some research to support it), that pronation is manipulated to direct the ball. The magnitude, velocity and timing of pronation may determine where the ball is going and has little to do with racquet head velocity.

Tennis strokes are very complex human movements and any simplification does our sport (and coaching) a disservice.

Let’s try to stay away from “snapping”, “whipping”, “muscle memory” and all the other terms that end up confusing all of us.

GR

[lukman41985]

Amen to that, Greg. Thanks for your input!

[gzhpcu]

Thanks for your input Greg. As to "aim the arm at the ball", what I meant is that the throwing action would seem to me to be directed up at the ball, rather than forward into the court. This results in a high elbow position after impact and the racket then pointing downward towards the court as Sampras, Becker, Edberg do, and Nadal, Agassi etc. do not do.

[johnyandell]

Some random comments here, because Greg basically already gave us all a great lesson:

The segments do not stop "abruptly." The hips and shoulder continue to rotate almost all the way through the motion--they just slow down.

Whipping my be the wrong concept--but as relaxed as possible is a good one.

The racket doesn't point downward until well out into the followthrough.

Hitting up on the ball is a great image/feeling for the serve, but doesn't necessarily correspond to reality.

Greg has written a brilliant thesis and he needs to get off his ass and get it approved.

His work will help us understand one of the big mysteries--what's the difference in the motion to go wide or down the T--and please I'm not asking for anyone's theory here... I mean he's quantified the exact path and speed of the racket.

[gzhpcu]

Since this is the site I give the most credibility to, I would like you to clarify a point showing up on two other tennis sites: the finishing position for a power serve, they say is "elbow high, forearm and racket pointing down", they speak also of this as being an "inverted V positlon" after impact. They even show exercises on how to achieve this.

Sampras and Roddick are cited as examples.

Any thoughts Greg?

[johnyandell]

Not sure about the exact position and I'll let Greg answer for himself, but it's a matter of when it happens in the motion. I'd have to look at the images.

You can the pronation and the finish here:

[gzhpcu]

Here's the finish they talk about:

[johnyandell]

Right, Pete goes thru that position--but it's not from the forward wrist snap if I recall the article. That position should happen naturally and not be forced, in my opinion.

[lukman41985]

John,

Do you find that position that Sampras is in 5 frames before contact, with the racquet face pointing directly towards the sky, unique? I've never seen any player get in that position on a serve. What a great piece of video! Looks like there's a 90 degree angle between the upper and lower arm. Looks like the hitting arm configuration you'd want on a good forehand, except with a service grip! Again, this seems like a unique position--I may be wrong. But modeling this position right now, the drop seems really natural with the backward rotation of the arm. Thanks for the clip!

[gzhpcu]

Right, Pete goes thru that position--but it's not from the forward wrist snap if I recall the article. That position should happen naturally and not be forced, in my opinion.

If you read the article "Serve it up" by Heath Waters on Tennisone:

I am always amazed at how quickly this one concept can improve and enhance any player's serve. It is not that we do not naturally use our wrist to some extent when we strike the serve, it is that we typically do not focus enough of our mental effort upon the snap and form of the snap during each and every serve that we attempt.

Observe how Roddick rolls the wrist from the cocked hammer position before contact to the pronated position you see in the finish with the racquet pointing towards the ground.

Once this is focused upon the lights will go off like fireworks. I guarantee it. For each and every serve you must make a conscious effort to snap the wrist like a whip and vigorously seek the proper form ending as we will demonstrate. So let's look at what I am talking about with Roddick's serve and then let's watch the test group do a drill that you can do yourself.

Think of the St Louis ARCH as a visual. However as soon as you achieve this position let your racquet naturally follow through so as to prevent injury.

To practice the wrist snapping action stand about 10 feet from the fence, get your racquet into the “L” position then toss and let her rip. Your focus should be on snapping your wrist through the ball to the ending finish of “elbow up and racquet head down” as you see Roddick and the test group demonstrating below. At first you may want to briefly hold this position, however, after you have mastered the basic form of “elbow up in an arched position and racquet head down” then let the racquet finish wherever it wants to without trying to stop it

[johnyandell]

Yeah well, I don't agree.

It may be a terminology thing. But if the argument is that the angle of the wrist breaks neutral at or right after contact, then this is not a description of what is actually happening.

There definitely is motion in the wrist to the netural position. To me it's not a "snap" and that sends the wrong message.

[gzhpcu]

I thought you wouldn't....

Jim McClellan goes on to analyze Nadal's serve and among other things also says:

Muscling at the Top of the Swing - Note the absence of an inverterted“V” as compared to the photo of Sampras .

Consider cracking a bull whip, or even a wet towel. The trick is to get the whip or towel swinging, and then abruptly stop the hand, even yanking it back ever so slightly, to crack the tip of the whip or towel. On the serve, with Pete, or Roger, or Bjorn, one would see a sharp inverted “V” at the top of the swing, the hand lingering up with the racquet snapping through and then down. Mind you that Nadal’s serve is pretty darn good. Note that both Agassi and Evert had the hand and arm in a similar position at this moment, but it truly indicates muscling.

[lukman41985]

Jim's wrong. Roger doesn't have that inverted V. You can see that in the video yourself. As Greg Ryan said, the inverted V is a result of Sampras using elbow flexion along with shoulder rotation and triceps extension. Federer goes through contact with mainly shoulder rotation and triceps extension--there is a lack of, or a minimum amount of, elbow flexion I think.

I have no idea what Jim's talking about when he says that Agassi is "truly muscling" his serve. He has one of the most effective serves out on tour. God didn't give him height, but he gave him the ability to go through the positions and hit a damn good serve, I think.

I don't think you want to abruptly stop with anything during a tennis stroke. Seems like you'd want to gradually decelerate the motion--that'd probably be more effective and abrupt stopping would probably cause an injury! The deceleration is probably a natural result of going through the motion. For example, from the drop, the triceps accelerate in extending but then decelerate as they reach maximum extension and the motion gets to the point where forward rotation of the shoulder takes over (the shoulder is accelerating forward in its rotation). The shoulder then naturally decelerates into the wrap and the recovery phase of the stroke begins. That's how I see it.

The guys over at tennisone.com use video, which is to be commended, but the conclusions they come to based on what they see--well I don't know how they came to them and I disagree with them.

By the way, Phil, now that you're discussing the contact phase of the serve, does that mean you've maximized your racquet drop? Any new videos?

John, do you mind commenting on my post, #11, in this thread? Thanks in advance.