Curiosity,
I don't like the biomechanical lingo. You aren't measuring anything just by using that term. I'll leave that type of breakdown to Brian Gordon who actually has. I prefer to just describe what hundreds of high speed videos actually show. The wiper is a combination of hand, arm and racket rotation. You think about it coming from the hand. Breaking it into components and trying to say so much rotation of the upper arm, so much of the lower arm, etc is a recipe for paralysis.
I certainly don't think of the windshield wiper as coming from the hand, and think anyone who does is oblivious. You don't, and I'll quote you below, from your New Method: The Forehand: The Windshield Wiper, below. I view the hand (and wrist) as essentially fixed through contact in the modern forehand. The exception, of course, is in the case of an incoming ball being so surprisingly far from the torso that the player has to flex the wrist out to it's natural lock position.
The reason I raised the question, whether you think of the term "windshield wiper rotation" as mainly flowing from ISR, (internal) rotation of the shoulder, versus simply a follow-through of an exaggerated low-to-high swing, is specifically this: I've run across quite a few advanced juniors, including one on his way to a national tournament, who had no idea that the latter notion was simply not what the thing was about. I'll also say, perhaps a bit that it isn't a result of "a counterclockwise rotation" of the upper arm in the shoulder joint, because that surely wouldn't work for Rafa. So I think learning that it is the Internal Rotation of the upper arm bone in the Shoulder joint ...is worth teaching even the 12- and 14- year-olds. It's easy to explain, and even to feel it happen with one's own fingers of one's off-side hand...if one knows where to grab the upper arm.
I'll reply separately and privately about what Gordon does and doesn't do. His "Developing an ATP Forehand," Parts 1 and 2, contains an amazing list of curious statments. I'll send a not-so-brief list of them to you privately. I've already written up many of them, but it's late at night. I'll review my work before I send it. Yes, he measures lots of things in the swing. He never explains the swing, and in my personal opinion mis-describes many aspects of it. I can myself, for that matter, measure a kid's swing speed every three months, and the changes over time in his arm position through the stroke. That tells the student nothing about HOW to control the amount and velocity of Windshiled Wiper rotation, which you yourself describe as possible..."with infinite variation. " He keeps claiming his conclusions all rely on his extensive and "scientific" database. I wouldn't call it scientific. I'd call it a technical database of kinesiological measurements. He also claims his conclusions are a result of his advanced bio-mechnical research. I'd call it kinesiology research, befitting his academic background at the Indiana University "School of Health, Physical Education, and Recreation." I'll leave the rest for a private communication. What he does is no doubt fine, as far as it goes. What he doesn't bother to do, for example, is clarify accurately the main drivers of that windshield wiper "clockwise rotation of the arm in the shoulder joint," and how a student can therefore improve the timing and power of those main muscle recruitments, which are actually and "scientifically," on evidence, under the control of the player. Perhaps you disagree. Point me to the part of either Part 1 or Part 2 where he gets to that....the lats, and how one controls them.
Gordon leaves out of his "scientific" analysis and "BEST System" descriptions the enormously important measurement, even description of, the sequence of...the particular muscular efforts involved in hitting, from start to finish, a modern forehand. No silver tags are required to accurately describe those....
I actually like and agree with your description of the universality and nature of the Windshied Wiper, quite apart from your reluctance to use two basic terms:
As you said so well in your video lesson “A New Teaching Method: The Forehand: The Windshield Wiper.” (I quote you beginning at 1:04 into the lesson): “So what is it, specifically? The wiper action is the unitary counterclockwise rotation of the hand, arm, and racquet in the forward swing. If we isolate the wiper motion, we can see clearly that as the swing moves forward the hand, arm, and racket are turning over as a unit. This is driven by the rotation of the upper arm in the shoulder joint. (Poster Insert: Yes. It's about ISR, and that follows ESR, which both of which easy to describe. We players and coaches can learn Spanish or Chinese in middle- and high-school, but not two simple terms?-ed.) This rotation causes the racquet tip to turn over up to 180º or even more in the course of the forward swing. Watch the racket tip rotate from pointing from one sideline to the other, from the contact out into the follow-through. Here the racket is turning over a full 180º in around 1/10th of a second. The effect? The wiper increases the ability to generate and vary topspin by increasing the vertical component in racket head speed. The result is the ability to create tremendous amounts of spin but also to vary spin by varying the amount and the speed of the wiper motion, and this applies across a wide range of contact heights, shot speeds, trajectories and shot placements. ….But, in the modern game this windshield wiper rotation has become a virtually universal element regardless of grip style even for players with more conservative grips, such as Roger Federer.”
YES!! ISR is now "virtually universal element," and have the ability to " also to vary spin by varying the amount and speed of the wiper motion," i.e. the internal shoulder rotation. And how is that done? By controlling the input of lat flex. How do you do that? Well, I think you know my favorite answer. Best.
