Supination on the Tennis Serve - When & Why?

[Chas Tennis]

Supination occurs during the tennis serve.

When and why is supination occurring on the tennis serve?
1) for positioning of the arm
2) to stretch muscles
3) to allow added range for pronation
4) as a consequence of some forceful motion
5) other.....?

The video on this site briefly discusses supination, pronation and internal shoulder rotation.
http://iws.punahou.edu/user/lcouillard/2008/08/pronation_supination.html

Illustrations and especially videos that indicate when meaningful supination is occurring would be very useful.

For example, at what time in this video is supination occurring? The Vimeo time scale is not consistent so that on one play 9 seconds is indicated while on another play 8 seconds is indicated. I think supination occurs when the racket starts the up swing, 8 or 9 seconds indicated. Describe phase of service motion.
https://vimeo.com/63688134

Recent thread on supination on the serve by luvforty.
http://tt.tennis-warehouse.com/showthread.php?t=453267&highlight=supination+serve&page=3

(In usage, supination and pronation are often used to mean either an anatomical joint position or a rotational direction. It is not always clear what is intended so it would be helpful to clarify your usage. I'm mostly using 'supination' to mean rotation in the direction of supination. Also, I assume that supination involves only the forearm from the elbow out to the hand. )

 

[toly]

This is Frank Salazar flat serve.
Picture1 shows the racquet’s long axis is parallel to upper-arm’s axis, but picture2 demonstrates that these axes are mutually perpendicular. Thus Salazar rotates the racquet around 90° by using forearm supination.

 

[charliefedererer]

Players coil as they go into their trophy position (pic 6).

As they push off with their legs and cartwheel, the racquet passively drops (pics 7, eight).

A powerful uncoiling motion causes the racquet to passively swing past vertical in the racquet drop all the way to supination (pic 9) with the racquet upside down.

The happy consequences of supination include:
1. positioning of the arm
2. muscle stretch
3. greater range of pronation
4. gives the "high elbow" coaches look for as the racquet drop/supination happens too fast to be seen by the naked eye in real time


For a nice slow video of a racqet drop from the rear into supination, check out Coach McCraw's video:
McCraw Serve Fundamentals http://www.youtube.com/watch?v=WuIgTyh4aDs
In it, he gives the tip that too many keep the racquet too close to the body in the take back - instead, bringing it back in a wider arc gets the racquet further away from the body so the arm can properly rotate into a better racquet drop, including swinging the racquet into supination.

 

[Chas Tennis]

Jay Berger's Comment about the Racket "Leaking" for the Back Scratch

We agree on which phase of the serve the interesting supination occurs in. Just before or during the phase with the supination is the 'back scratch' position.

Here is some discussion on a very interesting observation that Jay Berger made in a recent Tennis Channel Academy show. The wrist positions discussed below as #1 & #2 correspond exactly to the Toly pictures #1 & #2. Toly's #2 picture showns Jay Berger's "racket leaking".

Follow ">" link to see the full reply with quoted replies & pictures by SystemicAnomaly and links not shown in this quote.

Technical -

There was a Tennis Channel Academy show, "USTA Player Development", broadcast April 2, 2013 in our area.

Jay Berger was included coaching the serve. See minute 26.

He discussed a point that I've been confused about regarding the 'back scratch'. He used a term that I had never heard before - "racket leaking" - with regard to the 'back scratch'.

He also mentions briefly internal shoulder rotation.

For the leg thrust phase of the serve where the stretch shortening cycle is being used:

1) Forearm-Racket in Line. The forearm and racket should be roughly in line and at a right angle to the upper arm when the leg thrust phase of the serve begins. When the shoulder rises due to the leg thrust and other motions this forearm-racket to upper arm angle causes the shoulder joint to externally rotate and stretch the internal shoulder rotators (lat & pec). When the forearm & racket are in a straight line & at 90° to the upper arm, the moment of inertia of the forearm-racket is maximized. As soon as the wrist breaks to allow the back scratch, the moment of inertia decreases sharply. The racket has not yet "leaked" according to Jay Berger's terminology.


2) Forearm-Racket at an Angle. At some point after a good shoulder stretch is achieved, the wrist is allowed to let the racket drop down on the back - to the back scratch position. He calls this wrist joint motion 'letting the racket leak'. He discussed that the racket should leak but not too early because the stretch phase needs the forearm and racket more in a straight line. When they are in a straight line & at 90° to the upper arm, the moment of inertia of the forearm-racket is maximized. As soon as the wrist breaks to allow the back scratch, the moment of inertia decreases sharply. This can happen too early during the leg thrust before a good stretch is achieved.



This video shows both the forearm-racket in a roughly straight line followed by the wrist joint motion allowing the racket to go more into the back scratch position. Type of serve unknown.
https://vimeo.com/63688133

These videos of another service motion show some variation and not as much wrist joint change for the racket drop. Racket is out to side and not behind the back. Type of serve unknown.
https://vimeo.com/63688134
Another similar serve.
https://vimeo.com/63709517

This cleared up a confusing phase of the serve for me as he identified two things that I have seen in high speed videos and explained what is going on and a critical piece of timing.