Serve analysis 3D

[cgirard55]

Hi, my question is for Brian Gordan. Did you made the same analysis for the forehand? Can we consult this analysis?

Thank you !
Chris

[BrianGordon]

Chris-

Yes - I do the same type of analysis for the forehand - when I finish the serve article series, I will proceed to the forehand on this site - at that point you will be able to access the information in the interface along with my interpretation of what the information means to players and coaches - Brian

[bottle]

Internal Churning

Dear Mr. Gordon,

Over and over again, as I read tennis instruction, I find myself baffled by the terms "rotation" vs. "twist" vs. "upper arm pronation" whether the subject is serve or ground stroke.

Some of this confusion is undoubtedly due to my own denseness and failure to learn from past experience (and even violent discussion)-- you'd think I would have cracked the code by now.

On the other hand, different instructors use these terms in completely different ways.

Specifically, I am extremely interested in two sentences on page seven of your article, "The Serve Back Swing: The Upper Body."

"My research indicates," you write, "that not only are the muscles not aiding racquet drop through contracting external rotors, the muscles are actually attempting to internally rotate the shoulder in the opposite direction through
contraction of internal rotating muscles. This may seem surprising, but actually it is probably a critical factor in creating racquet speed."

Then comes one of the most fascinating animations ever seen in tennis history entitled "The external rotation in the backswing puts the internal rotators on stretch."

My question: Is the sleeve-like arrow around the upper arm, once it's red,
indicative of forward movement about to occur? In other words, are we about to spring loose some twisting, axle-like movement of the upper arm or is the upper arm and elbow going to spring loose "closer to body median," and is THAT the motion which we should pre-load.

I have no ax to grind, other than thinking I'd like to do one or the other or neither rather than both, and knowing that because of limited shoulder range I will spoil racket angle if I roll the axle-like upper arm forward (like a straw
rolled between thumb and forefinger) before extending the whole arm, thus creating lousy downward spin. Also, does centrifugal force from the cartwheel figure in extending the arm? Thank you.

[BrianGordon]

Bottle-

I appreciate the time you have spent looking at my work - it is evident you have have put forth some effort in that regard.

I'll attempt to answer your questions, but keep in mind, many of them relate to issues to be discussed in future articles.

Rotation is a generic term describing circular motion - it most commonly associated with the joints of the body - joints allow rotation in varying directions and the nomenclature is confusing.

Twist rotation is a non-scientific term indicating rotation at a joint around an axis aligned with the bone of the rotating segment - for example trunk twist rotation is conceptually around the spine, upper arm twist rotation (internal and external) is conceptually around the humerus.

Pronation is special term given to twist rotation of the forearm - I've never heard it used relative to the upper arm.

The text and graphic you mention speak only to the twist rotation of the upper arm - the upper arm is forced to externally rotate from trunk motion - the body takes "advantage" of this by contracting the opposing mucles (internal rotators) which lengthen even though they are contracting - the arrow (sleeve) graphic is simply the direction of muscle pull and in general may or may not be followed by future motion/rotation (however, in the case of the serve it most certainly is).

The "advantage" is putting these muscles in better contractile conditions for the upward swing.

Conceptually, you can think of the mechanism as an axle spring winding tight in the backswing as a way to improve axle twisting (upper arm internal rotation) in the upward swing - a major factor in racquet speed as we will see later.

The mechanism as described does not relate to non-twisting shoulder motion or elbow motion (extension). These are not the motions under pre-load consideration in the section you cite.

Interestingly, the upper arm twist rotation can cause elbow extension in the upward swing, and yes, the cartwheel (trunk) centrifugal effect causes arm (shoulder) motion - although probably overwhelmed by the tangential effect in creating another pre-load situation.

I believe the answers you seek may become evident in the discussion of the upward swing to come - part of the problem in splitting the motion into non-autonomous chunks - I propose you consider the future pieces and if your questions still exist, we can address them in the context of the full story. - Brian

[bottle]

Pre-load

Thank you so much, Brian, for your full response which at the very least succeeds in not making me feel like a worm. Beyond that, I greatly look forward to the upcoming pieces, and for now think I have a much clearer picture of what to try pre-loading next.

There aren't THAT many elements to choose from. I sometimes think we just need a good idea, the power of which is often underestimated by jocks. And knowledgeable focus from anyone helps everybody.

Thanks again-- your series is believably terrific.

[bottle]

Wow!!!!!!!!!!!!!!!!!!!!

I really did stumble on a substantial thing, didn't I, or elicit it, or muddle
through some complicated relationships. I always love it when my serve
begins to go twice as fast.

[John Yandell]

BG has some incredible things up there in his brain. I'm trying to comprehend more.

[mntlblok]

Shoulder stuff

I thought that I might be able to Google my way to understanding shoulder stuff. This site: http://www.pt.ntu.edu.tw/hmchai/Kine...r/Shoulder.htm
was my favorite, but it primarily served to show me that I'm not capable of understanding all that can go on with the shoulder.

With all the different bones involved - rib, clavicle, scapula, sternum, and humerus - and not to mention all the muscles and three dimensional directions in which all the joint combinations can move, I'm just going to have to take Brian's word for what to emphasize.

I did at least clear up one misconception that *I* had. The shoulder isn't in a fixed location relative to the spine. It can move a significant amount both 'up and down' and 'forward and back'. So, if it can do both internal and external rotation in addition to these movements, then it's just way too complicated for my little brain.

On the other hand, Brian has helped me to go from two second serves to almost having a *first* serve of my own.

Kevin