Marius_Hancu
Talk Tennis Guru
What I'd like to discuss here is the speed and acceleration of the racket during the takeback loop and during the attack of the ball at contact.
Let's use Sampras's running forehand as an example, because we have this magnificent closeup clip (OK, no high speed cameras, but free, and available to everyone)
http://www.dono.com.cn/tujie/sampras04.htm Running Reverse FH
(site is slow, be patient)
link - courtesy Exile
(use the slider on the left to slow motion)
Pls scroll down the slow-motion slider at the left of the picture to make the frames move at the slowest speed possible. This is important in order to observe the maximum of details.
Several things can be observed then:
1. Sampras is bringing the racket with the butt towards the ball up to the very latest moment (i.e. when the grip is right behind his right knee), even if he uses an Eastern FH grip, which presumably presents more difficulty in terms of establishing the proper racket face orientation and stability at contact.
2. After that, he starts the rotation of the racket in order to orientate its face perpendicular to the trajectory of the ball at contact.
3. The contact is something like 1 foot before his right knee.
The duration of the whole takeback loop (measured at the slowest frame speed I could get), up to the point described at item 1, is of about 9 frame periods (we're using here very rough time units, sorry), divided into 5 for the backwards movement and 4 for the advancing movement of the racket. This is a relatively short takeback loop, which is motivated by Sampras's style and the fact that he's under pressure in this particular circumstance. During it, the racket face is closed (facing the ground) but not fully. This close orientation of the racket face is quite important for keeping the ball in the court.
From item 1 to item 3 (contact), the duration is only of a frame period. The grip advances here only for about a foot, but the racket head, because of the rotation, covers something like 3-4 feet, of course in an arc resembling a quarter of an circle. The rotation of the racket axis is of about 90 degrees between 1 and 3. One can easily see that this is where the racket head suffers is major acceleration, and as a result it covers the largest distance between two subsequent frames.
One of the points which I want to make is that we should emphasize relative slowness and control during the takeback up to item 1, and acceleration and stability during 1 to 3. The "linearization" or "hitting 4 balls in a series" which has been discussed lately here, takes place in this interval.
Up to item 1, the major effort of Sampras is placing his body and the racket in alignment with the incoming ball, for a a maximum control and power at impact.
From 1 to 3, he's focussing on the acceleration and stabilization of the head of the racket.
There's of course a low to high movement of the racket towards the ball, in order to impart topspin, but it's not that accentuated, in order not to lose power.
The followthrough is relatively high and over his right shoulder (thus we're dealing with a "reverse forehand" here), but of course, it is not there that the speed and the trajectory of the ball is defined. It is defined of course by the racket-ball interaction at impact. Still, the followthrough is part of a continuum in the movement of the racket and should not be neglected.
Many amateurs make the error of trying to speedup the whole FH loop, instead of focussing on control and direction during most of it (including the pure takeback), and stability and acceleration during the very last part of it.
Also, they do not bring the racket butt towards the ball in the proper manner during the attack of the ball. One can observe the arm is quite straight during this interval (typical for the Eastern grip users), with one notable exception, at contact, where the elbow is a little bit bent, which is required by the leverage needed by the shot.
The torso/shoulders rotate only for about 90 degrees from takeback to followthrough, which guarantees less strain for the body. The power comes from this shoulder rotation but mostly from the upper arm rotation at the shoulder.
No significant wrist movement is observed, thus the risk of wrist injuries is minimized.
The knees are kept low throughout, in a very athletic stance, in order to keep the gravity center as much as possible aligned and behind the ball, to create stability and support. "Stepping into the shot" and the transfer of weight is obvious. Also, Sampras is moving in an arc intersecting the trajectory of the incoming ball, perhaps similar to what's recommended at revolutionarytennis.com and other sites. This would of course help the weight transfer, much more than what moving along a line parallel to the baseline would do.
P.S. In order to see all the great Sampras video clips available at that site, pls go to:
http://www.dono.com.cn/tujie/tujie.htm
Go to Pete Sampras section
and click on the Chinese characters in the left-most column to select one of the 7 clips.
(use the slider on the left to slow motion)
Let's use Sampras's running forehand as an example, because we have this magnificent closeup clip (OK, no high speed cameras, but free, and available to everyone)
http://www.dono.com.cn/tujie/sampras04.htm Running Reverse FH
(site is slow, be patient)
link - courtesy Exile
(use the slider on the left to slow motion)
Pls scroll down the slow-motion slider at the left of the picture to make the frames move at the slowest speed possible. This is important in order to observe the maximum of details.
Several things can be observed then:
1. Sampras is bringing the racket with the butt towards the ball up to the very latest moment (i.e. when the grip is right behind his right knee), even if he uses an Eastern FH grip, which presumably presents more difficulty in terms of establishing the proper racket face orientation and stability at contact.
2. After that, he starts the rotation of the racket in order to orientate its face perpendicular to the trajectory of the ball at contact.
3. The contact is something like 1 foot before his right knee.
The duration of the whole takeback loop (measured at the slowest frame speed I could get), up to the point described at item 1, is of about 9 frame periods (we're using here very rough time units, sorry), divided into 5 for the backwards movement and 4 for the advancing movement of the racket. This is a relatively short takeback loop, which is motivated by Sampras's style and the fact that he's under pressure in this particular circumstance. During it, the racket face is closed (facing the ground) but not fully. This close orientation of the racket face is quite important for keeping the ball in the court.
From item 1 to item 3 (contact), the duration is only of a frame period. The grip advances here only for about a foot, but the racket head, because of the rotation, covers something like 3-4 feet, of course in an arc resembling a quarter of an circle. The rotation of the racket axis is of about 90 degrees between 1 and 3. One can easily see that this is where the racket head suffers is major acceleration, and as a result it covers the largest distance between two subsequent frames.
One of the points which I want to make is that we should emphasize relative slowness and control during the takeback up to item 1, and acceleration and stability during 1 to 3. The "linearization" or "hitting 4 balls in a series" which has been discussed lately here, takes place in this interval.
Up to item 1, the major effort of Sampras is placing his body and the racket in alignment with the incoming ball, for a a maximum control and power at impact.
From 1 to 3, he's focussing on the acceleration and stabilization of the head of the racket.
There's of course a low to high movement of the racket towards the ball, in order to impart topspin, but it's not that accentuated, in order not to lose power.
The followthrough is relatively high and over his right shoulder (thus we're dealing with a "reverse forehand" here), but of course, it is not there that the speed and the trajectory of the ball is defined. It is defined of course by the racket-ball interaction at impact. Still, the followthrough is part of a continuum in the movement of the racket and should not be neglected.
Many amateurs make the error of trying to speedup the whole FH loop, instead of focussing on control and direction during most of it (including the pure takeback), and stability and acceleration during the very last part of it.
Also, they do not bring the racket butt towards the ball in the proper manner during the attack of the ball. One can observe the arm is quite straight during this interval (typical for the Eastern grip users), with one notable exception, at contact, where the elbow is a little bit bent, which is required by the leverage needed by the shot.
The torso/shoulders rotate only for about 90 degrees from takeback to followthrough, which guarantees less strain for the body. The power comes from this shoulder rotation but mostly from the upper arm rotation at the shoulder.
No significant wrist movement is observed, thus the risk of wrist injuries is minimized.
The knees are kept low throughout, in a very athletic stance, in order to keep the gravity center as much as possible aligned and behind the ball, to create stability and support. "Stepping into the shot" and the transfer of weight is obvious. Also, Sampras is moving in an arc intersecting the trajectory of the incoming ball, perhaps similar to what's recommended at revolutionarytennis.com and other sites. This would of course help the weight transfer, much more than what moving along a line parallel to the baseline would do.
P.S. In order to see all the great Sampras video clips available at that site, pls go to:
http://www.dono.com.cn/tujie/tujie.htm
Go to Pete Sampras section
and click on the Chinese characters in the left-most column to select one of the 7 clips.
(use the slider on the left to slow motion)
