Contact and Follow Through

very good for those who are interested in improving the game sincerely.

You are absolutely right in your analysis. I always found it funny how coaches in various sports come up with multitude of pseudo-scientific explanations of correct techniques. Though, if it helps to teach, who cares if it wrong or not
Just to add to your point, I believe swinging a racquet in a hammer position helps generate more speed as it uses stronger mussels in the arm. The problem is that if you continue with it through the contact you will lose speed (or hurt yourself) as wrist really doesn’t bend well in this direction. Instead it helps to turn it sideway to allow snapping through the ball.

Anatoly Antipin

2. About the Tennis Serve
The serve should be one of the easiest shot. It can be done from standard position. There are no hurry, no running involved etc. On the other hand, the serve is one the most difficult shot in tennis to learn because there is no clear explanation how to build the proper serving routine. Further, I’ll try to explain the most important and difficult to understand elements of the tennis serve.
Andy Roddick possesses one of the best serves in the world. There are some data of his performance. According to Figure 2.1 the Roddick’s right arm generates 80% of the ball speed. All others limbs actually are not very important and contribute merely 20%. That’s why I mostly pay attention on the right arm and its parts actions.
Figure2.1 Body parts contributions to the Andy Roddick serve
To go any further, we need to know a little bit about biomechanical terminology (Figure 2.2)
Figure 2.2 Biomechanical terms of the arm movement
In the tennis slang, the pronation means the counterclockwise rotation of the arm (not just forearm) and the supination is the arm clockwise rotation. The forearm pronation has restricted range around 180°. If your palm is facing the floor you basically cannot pronate at all. To make the pronation possible you should supinate first. If the palm is facing the ceiling, you can produce the most efficient pronation with range around 180°.
2.1 The Basic Kick Serve Routine and the Pronation
Almost all of the modern instructions advise the tennis player to drop the racket in a backscratch position and swing up on edge like you are trying to use the side of the tennis racket to cut the ball in half. At the last second before impact, the player has to pronate very quickly. In most cases the Continental grip is recommended. There are also a lot of words about legs, shoulders, trunk positioning and motion which I’m not going to analyze here in detail.
The pictures (Figure. 2.3) show the set of the video’s frames (last second before impact) taken during the pro Florent Serra’s kick serve and practically confirm instructions above.
Let’s analyze these pictures and try to figure out what is really vital in any tennis serve
ϴ=2°; Ωv=2°/ft41325678ϴ=3.5°; Ωv=1.5°/ftϴ=5.5°; Ωv=2°/ftϴ=7.5°; Ωv=2°/ftϴ=9°; Ωv=1.5°/ftϴ=11°; Ωv=2°/ftϴϴϴ Figure 2.3 Set of the pictures around impact
What can I state about the body rotation? It looks like the body is frozen (because it is very slow) and hence, it cannot contribute anything significant to the racquet’s velocity. But the arm itself and its parts are rotating in the different planes with the visible angular speeds.
Definition: The Target Plane is the vertical plane, which includes the tennis ball during impact and the imaginary target inside of the deuce or ad tennis court.
The arm is rotating in the vertical plane by using mostly shoulder joint (also very slow joint). This vertical plane should be parallel to the Target Plane to provide appropriate direction of the ball’s velocity. The distance between these two vertical planes is defined by the racquet’s size and orientation at the point of contact.
On the picture 2.3.1 the vertical ray with arrow indicates starting point of the arm vertical rotation. All others pictures include this starting point ray and its own ray for measuring angular movement of the
arm between starting point and current position of the arm (the angle ϴ). The numbers next to these rays show degree of the angle ϴ as result of the vertical arm rotation. On pictures from 2.3.3 to 2.3.7 the symbol ΩV represents angular speed of the arm for particular frame, ft is time elapsed between any two consecutive frames, ft=3.33 msec.
During this vertical rotation from Figure 2.3.1 to Figure 2.3.7 the arm travels 11° (Figure 2.3.7, ϴ=11°). The arm vertical rotation angular speed ΩV practically is constant on all pictures. It varies from 1.5°/ft to 2°/ft. The shoulder joint muscles do not produce any arm acceleration, it moves like a car coasts in neutral. Since, the arm is moving with constant speed the acceleration was achieved on previous steps of the serve, mostly, thanks to the fast elbow joint. The previous forearm movement forced the arm to move parallel to the Target Plane with angular speed approximately ΩV =2°/ft.
At the same time the arm pronation moves the racquet in the horizontal plane around 90°. Usually pros pronate something from 90° to 110°, depending on the previous supination. Suppose, the pronation provides 110° path of the racquet. It means the racket rotates in horizontal plane 10 times as many as the arm and racquet moves in vertical plane (ϴ=11°). The horizontal angular speed will be around ΩH=20°/ft, or 10 times as many as the vertical angular speed ΩV =2°/ft. Wow, this result is astonishing!!!
Question: Have legs, shoulders, and trunk motions contributed anything to the racquet horizontal rotation (pronation)?
Answer: These parts of the body produce a little bit to the arm and the racquet vertical rotation, but they are arguably even counterproductive for the horizontal rotation since the trunk rotates (clockwise), in opposite direction to the pronation (counterclockwise).
OK, it looks like I found the winner! The pronation can provide much bigger angular speed then others body limbs altogether.
Not so fast. In reality, we are interested in the linear velocity (the speed and direction) of the racquet, not just in angular speed.
Definition: The linear speed = radius × angular speed. The direction of this velocity is perpendicular to the radius of the rotation in the plane where the point of contact rotates.
The angular speed already discussed above. But, what is the radius? The figures 2.4.1 – 2.4.4 give an idea about calculation of these radiuses.
β=35°RHRVO RVβ=40°RHRVO
Figure 2.4 Federer serve Figure 2.5 Henin serve
β=45°RHRVO β =45°RHRVO Figure 2.6 ljubicic flat serve Figure 2.7 Stosur spin serve
Definition: Racquet efficient length Rel is the distance between player’s hand (point O on the Figures (2.4-2.7) and the ball during impact. I think Rel = 25” (63.5 cm) in the most occasions.
Definition: Arm efficient length Ael is the distance between shoulder joint and player’s hand. Since everybody have different arm size, I assume Ael = 25” (63.5 cm) as average length.
On the pictures above, RV is the radius of the arm and the racquet vertical rotation, RH – the radius of the racquet horizontal rotation (pronation).
RV = Ael + Rel × cosβ =25” × (1+ cosβ), where
β is the angle between long axis of the racquet and axis of the forearm (Figure 2.4-2.7). RH = Rel × sinβ=25” × sinβ
RV can vary from Ael to Ael + Rel (or from 25” to 50”) because cosβ has range from 0 to 1, depending on the β magnitude. RV can be never equal to zero, because Ael or the arm efficient length is constant and equal to 25”
RH can vary from 0 to Rel (or from 0” to 25”) because sinβ has range from 0 to 1. RH can be equal to zero and therefore linear speed would be zero! It can be very big problem for the tennis player. Maintaining the proper magnitude of the angle β before impact is absolutely crucial for pronation! On figures from 2.4.1 to 2.4.4 the best players keep β from 35° to 45°depending on the serve type.
Notation: |VLV| – Linear speed of the racquet in the vertical plane; |VLH| – Linear speed of the racquet in the horizontal plane. VLV and VLH are corresponding velocities. Reminder: the linear speed = radius × angular speed. In the last formula the angular speed should be expressed in radians. The angular speeds in degrees (from Figure 2.3) were: ΩV =2°/ft, ΩH=20°/ft. In radians they are ΩV = (π/90)/ft, ΩH = (π/9)/ft.
Then linear speeds in the vertical and horizontal planes can be calculated according to the following formulas:
|VLV|= RV × ΩV = 25” × (1+ cosβ) × (π/90)/ft = 25” × (1+ cosβ) × (π/90) × 300/sec
|VLH|= RH × ΩH = 25” × sinβ × (π/9)/ft = 25” × sinβ × (π/9) × 300/sec
The sum of the linear racquet speeds would be |VLV|+ |VLH|.
The results of the calculation are presented on the Figure 2.8
Figure 2.8. Linear speeds of the racquet in vertical |VLV|and horizontal |VLV| rotations and their summation
The data on Figure 2.8 demonstrate, if the angle β ≥ 12° the linear speed of the pronation begins to prevail on the linear speed of the vertical rotation.
OK, it appears, I found the proof! The pronation can really provide much bigger linear speed of the racquet than others body limbs altogether! But, if the angle β=0° the pronation produce nothing at all just the wrist perhaps can transfer some energy to the vertical rotation.
That’s why I repeat again, the best tennis players keep the angle β around 30° – 45° (Figure 2.4 -2.7). Maintaining the proper magnitude of the angle β before impact is absolutely crucial for pronation! If the angle β has the proper magnitude the pronation would be the most important and effective contributor to the powerful tennis serves!
2.2 The Serve and the Wrist Action
There are a lot of speculations about the wrist movement (the wrist snap, the wrist whip effect) during the last second before impact. Some of the tennis specialists (Vic Braden etc) say no such thing occurs. But, others (Brian Gordon and so on) insist the wrist is very important.
But what does the wrist really do? When I’m serving I feel like my wrist is doing something very essential, however maybe my feelings mislead me. But, the pictures never lie.
This time I’m going to analyze the pictures (Figure. 2.9 and Figure 2.10). They show the set of the video’s frames (last second before impact) taken during the Florent Serra and Lleyton Hewitt serve. Let’s pay attention to the wrist motion.
123145678 Figure 2.9 The wrist at the last second before impact (Florent Serra’s kick serve)
123145678Figure 2.10 The wrist at the last second before impact (Lleyton Hewitt’s serve)
From above pictures we can see the racquet string pane has the practically constant vertical orientation. The hand is absolutely out straight and there is no extension or flexion of the wrist before and for the duration of the impact.
At the same time the wrist ulnar deviation directs the racquet upward very fast. The pictures on Figure 2.9-2.10 show this movement takes place in the plane which coincides with the racquet string plane. Hence, it can produce the brushing boll motion only. But, the brushing motion mostly responsible for the ball rotation, not for the ball speed.
The wrist ulnar deviation might be used to create different types of the spin serves and this is a very good option. But, it also can destroy pronation (it reduces the angle β, see step 2.1), the most important part of the tennis serve.
The tennis players must exploit the wrist ulnar deviation very cautiously, because it can completely destroy the pronation component (|VLH|) of the racquet speed!
OK, so far I don’t see any wrist snap which could add any real speed to the tennis ball, but the spin only!
But, maybe there are also some tennis players with different serve routines?
Yes, for instance Chanelle Scheepers. She has radically different serve’s course of action (Figure 2.11).
123145678123456789101112
Figure 2.11 The wrist at the last second before impact (Chanelle Scheepers’s serve)
Chanelle Scheepers’s fastest serve speed at Roland Garros 2010 was 98 mph, average 1st serve speed 90 mph, and average 2nd serve 78 mph. Her height is 5′ 9″ (1.74 m). 1st serve: 73%, 74%, 82%,80%,77%,78%,79% . 1st serve reliability more then 75%.
Definition: Open face – the racquet is said to have an open face when the string surface hitting the ball looks upward towards the sky.
Chanelle Scheepers bent her wrist backward. That opened the racquet face around 60°, nearly to the water’s tray position (see Figure 2.11.1; 2.11.2). Then she rotates the arm in the vertical pane with the angular speed ΩV =1.3°/ft and pronates in the horizontal plane. She flexes the wrist in the vertical pane with the angular speed ΩW=6.5°/ft. Besides, Scheepers creates extreme ulnar deviation. The last action has completely destroyed the pronation’s component of the racquet velocity |VLH|, because the arm and the racquet represent the straight line (the angle β=0, see step 2.1).
The back scratch metaphor developed to help you drop the racket down behind the back in a tear drop fashion to avoid placing the racket in the dreaded waiter’s tray position, photo right. After you do the racket “down and up” part too often the hand lays back
Next text must be deleted!!!!! , leaving the racket face facing up like a waiter’s tray, instead of moving to place the racket down behind your back (more later).
At the same time the wrist ulnar deviation direct the racquet upward. The pictures on Figure 2.9-2.10 show this movement takes place in the direction parallel to the racquet string plane, hence it can produce the brushing boll motion only. But, the brushing motion mostly responsible for the ball rotation, not for the ball speed. The wrist ulnar deviation creates different types of the spin serves, but also can completely destroy pronation, the most important part of the tennis serve.
Next Text should be deleted.
Pros talk wrist snap, scientists/observationists say no such thing occurs. Scientists like to opine, “often what they [pros] say is not what they do.” Are the pros wrong?
Many self styled tennis scientists look at the film evidence and say, “Aha! The key is to pronate the forearm and hand/wrist!” But the loudest voice out there says you do not snap your wrist. In fact, Vic Braden says his “studies show there is no wrist snap on the serve; anatomically it just does not happen…. In high speed photography, the only time we find the wrist bends during the serve is in the middle of the loop, not at impact… [because] the hand is absolutely out straight; there is no displacement of the wrist at impact.” Vic doesn’t offer this as a curious fact but to support his claim a wrist snap is “a myth.”
On the right is Vic captioned illustrating “think pronation, not wrist snap” [TENNIS magazine, August, 1989, photo by Dom Furore], below that is Vic’s serve swing in strobe-like effect (from his 1977 book Tennis For The Future) that shows the pronation turn-out of the racket just after contact for two images before it turns back in (due to a wrist bend, but more later).

Extremely usefuL!! thanks a lot for the lessons

Good breakdowns and very clear

very good, i like very much thiis video

im having some trouble with pronation do you have any tips for me to hit the ball effectively?

-christian

I am a biomechanist and have had the opportunity to perform very detailed analyses and computer simulations of the strokes of top badminton players. Although badminton and tennis have quite different stroke techniques, they share the importance of pronation. This is a little difficult to explain in text, but imagine your wrist straight, such that the hand is a perfect elongation of the forearm. In that case, the held racket will stick out perpendicularly from the line of the forearm. Now, if you pronate, you will produce real velocity of the racket head. However, in an overhead stroke, to hit the ball high, you want the racket to be an extension to the forearm when you hit the ball as opposed to being perpendicular. This can be accomplished by wrist adduction, i.e. by bending the wrist sideways. Here comes the trick: The wrist is a cardan joint like the one you have in the drave shaft under a truck. It can bend two ways compared to the forearm, but it cannot rotate. This means that, if you pronate the forearm with the wrist adducted, you can generate linear speed of the racket head using forearm pronation.

Excerpt…

[...]Virtually anybody can be taught and apply primary copywriting tips to land freelance writing gigs. Listed here are a few copywriting suggestions which have develop into[...]…

Excerpt…

[...]promoting a service or product, the usage of storytelling will be totally effective. Lead your viewers via example and influence[...]…

Great website…

[...]we like to honor many other internet sites on the web, even if they aren’t linked to us, by linking to them. Under are some webpages worth checking out[...]……

Thanks.