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Chas Tennis
05-31-2012, 08:10 AM
Background - My interpretation of some biomechanical research results on the serve-

During the service motion, first, the tossing shoulder is up and the hitting shoulder is down. Then the hitting shoulder is very rapidly moved high using trunk lateral flexion. Last, the final racket head speed is increased to ball impact using mostly internal shoulder rotation. Internal shoulder rotation contributes the most to racket head speed.

The internal shoulder rotators are pre-stretched by the leg thrust. The stretch occurs because the upper arm is at about 90 to the body and the racket and forearm are at about 90 to the upper arm when the legs thrust up and carry along the shoulder. This externally rotates the shoulder stretching the internal shoulder rotator muscles. The internal shoulder rotator muscles are the lat (Latissimus Dorsi), pec (Pectoralis Major), Teres Major and some others. The largest muscle connected to the arm is the lat, the second largest is the pec. Both insert on the front of the upper arm at the same location and internally rotate the shoulder by pulling on the humerus at that insertion point.

The question is what part does raising the hitting shoulder play in farther stretching the lat or in maintaining the stretch?

Apparently it is well known that raising the shoulder can increase the lat stretch.

From the Manual of Structural Kinesiology, C. Thompson, R. Floyd, 15th ed., page 89:

paraphrasing

The stretch (of the lat) may be increased ................by then laterally flexing and rotating the trunk to the opposite side.

(This is a great basic reference. It is a popular college text and the latest edition is $75 while the recent editions like the 15th are just $10 or so.)

Lateral trunk flexion is just the side bend that puts the hitting shoulder up. Rotation of the trunk is just the trunk turn that is used for serving. Both of these lat stretches can easily be felt by just holding the upper arm at 90 to the body and rotating the forearm up and back as in the service motion to give the internal rotators some stretch. When stretched in that way, laterally(side) bend the trunk, feel the lat stretch. Also rotate the trunk and feel the lat stretch.

In Knudson's book, Biomechanical Principles of Tennis Technique, I think he discusses the speed of stretched muscles as more rapid.

Does this late trunk flexion and rotation play an important part for the serve by final stretching of the lat for added racket head speed?

LeeD
05-31-2012, 10:56 AM
Maybe you should look at throwing a ball. You are waay overthinking a simple motion. Learn to serve, not learn what is behind the mechanics of serving.
OTOH, this thread is a nice excercise in useless information, so it should draw plenty of replies, most very good reading.

TennisCJC
06-01-2012, 12:43 PM
Yes, throw a heavyball like a football to get the feel and don't over think it.

If that doesn't work, isolate a few key points in the serve, like get the front arm and shoulder up and hitting "up the mountain" as you go up and into contact.

If that doesn't work, see a pro for some lessons to debug your serve.

tricky
06-01-2012, 01:20 PM
The question is what part does raising the hitting shoulder play in farther stretching the lat?Mmm, the casual relation itself is actually in reverse. The lat stretches due to the tilt of the trunk, and the tilt of the trunk is partially effected by the tossing motion (if the hips are loading.) When the lats stretches, this causes a shoulder adduction, but as the eccentric phase.

What happens with many servers is that they self-consciously form the trophy pose by lifting the shoulder, as if making a touchdown gesture. When they do this, they break the kinetic chain from the trunk to the shoulder. Not only does it weaken the serve, but it throws off the timing of the motion.

It all comes together if your toss is good, and your weight moves into court from the beginning of the toss.

Chas Tennis
06-03-2012, 09:15 AM
................. The lat stretches due to the tilt of the trunk, and the tilt of the trunk is partially effected by the tossing motion (if the hips are loading.) When the lats stretches, this causes a shoulder adduction, but as the eccentric phase.

What happens with many servers is that they self-consciously form the trophy pose by lifting the shoulder, as if making a touchdown gesture. When they do this, they break the kinetic chain from the trunk to the shoulder. Not only does it weaken the serve, but it throws off the timing of the motion.
......................

I am trying to identify all stretch details of the lat associated with motions of the serve.

Here is some more detail. I'd be interested in how the points that you mentioned correspond to these points.

This description from the Manual of Structural Kinesiology is not for the serve but in general identifies some motions and their effect on stretching the lat. These motions are all present in the serve, in fact, the description reads like part of the service motion.

"The latissimus dorsi is stretched with the teres major when the shoulder is externally rotated while in a 90-degree abducted position. This stretch may be accentuated further by abducting the shoulder fully while maintaining external rotation and then laterally flexing the trunk and rotating the trunk to the opposite side."

Breakdown-

1) "The latissimus dorsi is stretched with the teres major when the shoulder is externally rotated while in a 90-degree abducted position."

The corresponding parts of the service motion are 1) the upper arm aligned with the line between the shoulders ("90-degree abducted position"). 2) External rotation occurs from the shoulder external rotators and also because the forearm and racket are bent, say, at very roughly 90 degrees to the upper arm when the legs thrust up. The inertia of the forearm and racket stretch the internal shoulder rotators.

2) ......"This stretch may be accentuated further by abducting the shoulder fully while maintaining external rotation..."

There is no corresponding part of the serve because it does not occur in proper technique since farther abducting the shoulder results in more risk of impingement. (McLennan & Ellenbecker videos on shoulder injury) The upper arm should remain in a rough line with line between the shoulders.

3) "...while fully maintaining the external rotation and then laterally flexing the trunk ......................"

The corresponding part of the serve is the lateral trunk flexion that brings down the tossing shoulder and raises the hitting shoulder. Probably starting, as often recommended, with the front hip bowed forward allows more range of trunk flexion and therefore greater lat stretch. ? I have not seen another clear explanation as to why having the hip forward would help the serve.

4) "while fully maintaining the external rotation and then .........rotating the trunk to the opposite side."

The corresponding part of the serve would be 'body turn' (sometimes loosely called 'shoulder turn.') Rotating the trunk can stretch the lat. Also, pointing the chest up, stretching the lat, and then rotating the trunk forward can farther stretch the lat. This may account for the 'chest up' recommendation often heard. Otherwise, what is the reason?

I have sort of a stretch-then release viewpoint where the lat muscle is first stretched for internal shoulder rotation and then released. Maybe some of these stretching motions could also drive the serve very fast more directly. ?

decades
06-03-2012, 09:17 AM
there is a bill tilden teaches the serve video floating around. he isn't thinking about bio mechanics. if we all could just capture that fluidity.

CRWV
06-03-2012, 11:35 AM
... a nice excercise in useless information...

LeeD
G.O.A.T.
Join Date: Dec 2008
Posts: 15,858

Guy wasn't looking for good advice about his tennis playing, he asked a specific question. (an interesting one, at that)