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Copyright © 2019 by Michael Jacobs All Rights Reserved. This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher, except for the use of brief quotations in a review. Printed in the United States of America First Printing, 2019 ISBN 9781797556338 RSB Golf Inc. 105 Clancy Road Manorville, NY 11949 www.jacobs3d.com

CONTENTS FOREWORD, by Dr. Steven Nesbit................................................................................................................................9 INTRODUCTION: Science of the Golf Swing........................................................................................................11 CHAPTER 1: Kinematic and Kinetic Classroom...............................................................................................17 CHAPTER 2: The Hub Path.............................................................................................................................................147 CHAPTER 3: Resistance......................................................................................................................................................181 CHAPTER 4: The Lesson Tee..........................................................................................................................................273 Lesson 1: Lesson 2: Lesson 3: Lesson 4: Lesson 5: Lesson 6: Lesson 7: Lesson 8: Lesson 9: Lesson 10: Lesson 11: Lesson 12: Lesson 13:

Grip Alignment ................................................................................................................274 Grip Placement ...............................................................................................................274 Body Segments ..............................................................................................................277 Spine .......................................................................................................................................279 Segment One ...................................................................................................................281 Backswing Blueprints ................................................................................................283 Radius of Curvature ....................................................................................................286 Backswing First Half ...................................................................................................288 Backswing Second Half...........................................................................................290 Late Backswing ..............................................................................................................297 Transition .............................................................................................................................302 To Last Parallel ...............................................................................................................308 To Impact onto the Finish .......................................................................................324

AFTERWORD, by Brian Manzella...................................................................................................................................331 ACKNOWLEDGMENTS...............................................................................................................................333

FOREWORD BY DR. STEVEN NESBIT

Michael Jacobs has created the most impressive golf science book I have ever read—and I have read them all. This amazing book successfully bridges the huge and empty expanse between the physics that describe the golf swing and the practical applications that serve to benefit all those who play and teach. Mike really digs deep into the fundamentals and nuances of the swing. There is considerable new information that is not only useful for describing the swing, but that actually matters to the mechanics of the swing. This is very dense material. The physics are presented and their relevance to the golfer explained, and, most importantly, Mike offers the application of these physics to the golf swing in a way I particularly value—with a wealth of examples that demonstrate the good, the bad, and the variety. You may just see pieces of yourself in these pages! Mike’s straightforward language and excellent graphics make understanding this material inevitable, and the reading and studying both enlightening and enjoyable. From this information and understanding, the direct application to your own swing mechanics becomes almost intuitive. This has been an extremely rewarding journey with my friend Michael Jacobs and his Jacobs 3D project. It has been so much fun to dive deep into the raw material of a golf swing and decipher the

intricate motions and transfer of driving forces and energy that occur. It’s fun because the work has been professionally challenging, and rewarding because it has opened the doors to so many other avenues of golf research and application. One of the highlights of doing research with Mike is seeing how it plays out in practical application. There’s a real symbiosis at play from our collaborations. In all my years of modeling, measuring, and analyzing golf swings, I get asked the same question repeatedly: “What is the one thing that is most important to know about the golf swing?” I can say with absolute certainty: There is not just one thing. There are many things one should know and understand. This book will help you on that quest to learn those things that matter. But get outside academia and it’s easy to see how someone could be buried in all of this available information. That’s why Mike’s part in this is so important, in fact the most important—and why he’s a recognized and exceptional golf scientist and instructor. Mike has proven he can translate this information in a way that’s useful to his students—and to the world of golf. This book does not rely on clever analogies. Using analogies to help teach golf students is commonplace, and it has been for years. However, the golfer and teacher are burdened with

useful but limiting “analogies” such as “the swing is a wheel,” or “turn in a barrel,” for communicating swing concepts and improving techniques through non-technical means. The information in this book replaces analogies with facts and concepts that need no interpretation to directly and effectively understand and apply to the swing. This book shows teachers and players from the novice to the professional the scientific underpinnings of the swing—and it offers a fascinating preview of the work Mike and I are doing revealing exactly how the body works in producing the unique swing characteristics that each one of us possesses. The Science of the Golf Swing— and, before it, The Elements of the Swing—get anybody willing to put in some time and thought the ability to understand this amazingly useful viewpoint of the golf swing. It opens so many doors. I am confident if you put in the time and

Foreword

effort into learning and applying the information in this book you will become a better and more knowledgeable golfer and teacher. It is clear to me why Mike is one of the best golf teachers in America. Let him teach you through his unique approach that combines golf science, extensive experience, and practical examples. I’m excited for you to read The Science of the Swing, and I’m looking forward to what comes next with my friend Michael Jacobs. Once again, this is truly an amazing book!

Dr. Steven Nesbit Department of Mechanical Engineering Lafayette College Easton, Pa.

INTRODUCTION To say the release of the “fundamentals” book in 2016 broke ground in the world of golf would be an understatement. It was fantastic to hear from thousands of golfers about how the analysis in the book helped them see their own swings in a completely different way—and how seeing the physics of the swing influenced the way they thought about making changes and improvements. The highlight has been seeing the excitement the book has created about the prospect of solving all the questions about the movement of the club that have never been within the grasp of a golfer before now. As I always say to Dr. Steven Nesbit—my friend and collaborator—we are ending the search for the perfect swing. There was also plenty of back-and-forth about the relative merits of “engineering-based” golf instruction vs. the “old school” style of teaching— and even about the relative merits of what Dr. Nesbit and I have put together in this program. I can break down the vast majority of the feedback I’ve gotten about the book and Jacobs 3D into four basic categories, or questions. I want to start off this “master” sequel to the original Elements book by talking about this feedback and giving some background about how this project came to be—and what the goals for it (and this book) are.

Does Golf Have to Be Complicated? Some of the loudest commentary came from the group of golfers that believe a golf swing is a simple movement closer to an art than a science. They see graphs and data and hear some of the terminology thrown around at the top level of these discussions and come to the conclusion that average players couldn’t possibly understand or need that level of detail. It’s a ball and a stick, they say. Making it more complicated just locks people up. They can’t see the forest for the trees. To be honest, they are in the vast majority—and there is a place for that. But for those who have golf in their blood and spent a lifetime trying to master the swing, the journey that I am going to lay out through this book (and the ones to come) will be fascinating. Dr. Nesbit and I are revealing the unconstrained truth about the physics of golf club and human body movement. Golf has had centuries of kinematic diagnoses—descriptions and analysis of two-dimensional movement—without any insight about what actually caused the motion. Kinetics is the branch of dynamics where the explanation of movement is answered using classic Newtonian physics. Kinetics cause the kinematics (force and torque

cause the movement), and there are certain kinematics that are very informative once the kinetic is revealed. This is where one of the most common misconceptions about the “science of golf”—at least how I’ve learned it and now teach with it every day—comes from. There is a massive difference between becoming an expert in the fine details behind the physics of the golf motion and becoming an expert at applying the principles into a golf swing. You can be an expert in the field of golf science and be a terrible golfer. And you can have no knowledge of how the golf swing really works and still be an effective player or coach. You can also know a lot of the scientific information we’re going to talk about in this book and yet talk about the golf swing in a language that is recognizable to anybody. Golfers come in the same kinds of categories. You can be a player who wants to know all of the details, like Tiger Woods or Bryson DeChambeau. You can also be a player who wants to keep the game as instinctive as possible, like Fred Couples or John Daly. This might shock you to hear from a supposed “science guy” like me, but I think all of that is great. It’s great that some instructors get fantastic results because of the quality of their psychology, and their instincts about making swing changes to help a player. It’s also great that some players want to know how all the knobs and dials work, while other ones want to hear it as simply as possible. The world is filled with all different kinds of people, and all different kinds of learners. If you’re going to be in the business of teaching anything—whether it’s hitting a golf ball or third grade—you’re going to reach more people if you can adapt your approach to fit a learner’s personality and learning style. So, does that mean golf instruction has to necessarily be complicated? Yes and no. When you take your car to a mechanic to get a specific problem fixed, the problem could be a simple one—and the mechanic could be somebody with lots of experience fixing that particular problem. The problem could also be complicated

Introduction

and hidden deep down in the bowels of the car. Developing a complete understanding of how the club moves and the body works takes time and study—and it’s not always easy sledding. This is the point where some of the criticism of “modern” golf swing analytics starts to go off the rails. Let’s say you’ve spent a ton of time and effort to learn all of this “under the hood” stuff, and you’ve also trained for hundreds of hours on how the physics of the swing translates from player to player. I’m not sure where the idea comes from that this level of expertise means a teacher who has that expertise is going to bury a player in pile of jargon—or get them lost in a sea of complicated technical points and swing thoughts that make the swing worse, not better. Are there teachers who do a bad job integrating technology into their instruction? Sure. There are also teachers who don’t use any technology, and roll out the same three or four instruction points they’ve been using for 25 years, regardless of the student and regardless of the problem. There are also scientists who do over simplify their research studies and derive the wrong conclusions. My answer to those kinds of challenges is always the same. The true kinetics of the movement of the club had never been properly studied and explained. We have seen simplified models, but it wasn’t until Dr. Nesbit came along in 1988 that we got the entire story. And even that was delayed. After he did his contractual work with the USGA, he wrote some research papers of discovery that set the tone for golf science in the new millennium. Although Dr. Nesbit built the physics model, there was no golf professional to assist him with the explanation of what it means to a golfer. Over the years I have been able to supply him with that and the desire for him to learn what it means to golf has been awesome to witness. We’ve uncovered details within his models of the physics that were even news to him. In our meetings he always says, I just supplied the physics and never delved deep into the nuances of its application. This is what makes him a true scien-

tist; He is opened minded and explores all of my conclusions and inquires. Of all the golf science available, Dr. Nesbit’s interpretation of the physics is unparalleled and my studies with him have given me more information on which to base my opinions. I think of it as being a writer who has access to two alphabets. I can work with a student like one of my top junior players from China, who does not speak English, and get across important instruction points without using any words at all. And if one of my technologically advanced teaching friends or data-junkie students comes by and wants to dive deep, we can do that, too. It’s great to have choices.

Introduction

golfers over the years, and it has prevented tens of thousands more from reaching their full potential. By the time I got to Methodist University in North Carolina, I knew my future wasn’t as a player, but as a teacher. And I knew I wanted to be a teacher who could help players unravel the mystery of the swing. While in the Professional Golf Management program at Methodist, I dove deeply into Homer Kelley’s Golfing Machine, along with Search for the Perfect Swing from Cochran and Stobbs. My favorite college course was Jerry Hogge’s Science of the Swing class, where we devoured Search for the Perfect Swing with a professor from the physics department. Dr. Singh probably doesn’t remember me, but he was so influential in setting me out on this mission. He and I would go through Jorgenson’s Physics of Golf after every class, and the seeds were planted that would eventually bud at Lafayette College with Dr. Nesbit many years later.

Why Are You Doing This? From the time I started in this business, 21 years ago as a 19-year-old on a summer internship on Long Island, I’ve always been driven by one thing. I never wanted to be in a position where a student asked me a question and I didn’t have the answer. I wanted to know. I had also gone through a lot of frustration with my own game over the years. As a kid, I was the athlete who could pick up any sport right away. I played baseball, basketball and football, and when I got hooked on golf, I thought it was just a matter of putting in the time to practice and I’d be really good. It didn’t quite work out that way. I devoured every golf book I could find, and I wired my parents’ VCR up to record every PGA Tour event, so I could watch the tour players swing. I researched who the best teacher in my area was, and I took lessons religiously. But all the information I got— from television, the magazines, my teacher—conflicted with itself, and worse yet, it didn’t help me get any better. In fact, I started getting worse. To give just one example, the first thing I learned at junior golf camp was that you could never have enough forward shaft lean. Tell that to a kid who was as determined as I was and you’re going to get somebody who sets the record for alpha torque. That lag conversation has destroyed thousands of

What is the One Thing Everybody Wants to Know? Interestingly enough, this process of answering questions and identifying new problems has inspired one very common question from players and teachers. I get at least one every day in an email or on the discussion forum at my website. Everybody wants to know what the single best way to swing is. Because my Jacobs 3D software produces something called the “hub path optimization”— the ideal path your hands should take through the swing—a lot of people think that means they can skip all the preliminaries and just get right to that. Here’s my swing, they say. Tell me what I should do. Or, they figure that there must be an optimum “swing model” that everybody should be copying, like Ben Hogan’s swing. There are all kinds of good-looking swings out there, and lots and lots of ugly ones. Some of those beautiful swings produce great shots, and some of those ugly ones do, too. That’s an extension of the fundamentally fascinating point Dr.

Nesbit has made time and time again during the time we’ve spent together. So many people want to hear that there’s one optimum way to swing the club. But there are lots and lots of efficient ways to do it. There are reasons why relatively small players can sometimes produce lots of clubhead speed, and why some giant people can’t swing very fast at all. Golf swings are like songs. All different kinds produce happiness. Lots of different kinds “work.” Where the skill of the instructor (and, by extension, the player) comes in is understanding how the sum of a swings parts work together with the physical realities of the player making the swing. There is no perfect swing, but there’s an efficient one for you. If you come into this book (or the previous one) looking for the single answer for every swing—the “how”—you’re probably going to be disappointed. The how is good to know, and there’ll be time to talk about that down the road, but the much more important and interesting question is the “why.” Take your time and work through the information in this book and you’ll discover the definitive “why” behind the way the club moves. When you know the why, the how will be very obvious!

How Do You Know Your Stuff is Right? The history of research into the golf swing is actually pretty simplified. Through the years many players, teachers and scientists have worked to accumulate as much data as possible about the swing—from the still footage models of David Williams, to Giedon Aeril’s Biomechanics all the way up through Jacobs 3D today. But the vast majority of the research that has been done on the golf swing has been simplified. This is because until the 1990’s, it was way too difficult to model the entire three-dimensional phenomenon of the golf swing. So many researchers were constraining their models to two dimensions—a planar model—with the assumption that the path of the hands was circular enough to constrain the mathematics to a constant radius circle.

Introduction

When you look at a swing in a picture sequence or on video, you’re seeing a “flat” image in 2D. It limits most research to measuring the location of the club and the body during various parts of the swing and trying to establish relationships from there. Most scientific models—even the ones you see from other respected golf scientists—either project the swing into 2D or still follow the same re-creation of the 2D mathematics of yesteryear. The golf swing has a bunch of moving parts, and it happens on all kinds of changing planes of motion and ever changing radii in movement paths made by players of all different shapes and sizes. With so many variables, the natural tendency is to simplify the analysis by removing variables to make the math easier. Dr. Nesbit didn’t apply any constraints to his mathematics, and here we sit with an explanation of the golf swing that was never thought to be possible. The engine behind Jacobs 3D—and the books you’ve been reading—is the most advanced three dimensional sports movement algorithm in the world. Dr. Nesbit has built upon his work for the USGA building the predictive model they use to test drivers for rules compliance to create a system that not only shows the forces and torques at work on the golf club during a swing, but how the various segments of the body contribute to producing movement. (The body element is the absolute cutting edge in swing analysis, and “Alpha Man,” as we call him, is going to be the hero in the next series of books and research publications that we produce in the future.) Could somebody argue that Dr. Nesbit’s convention of applying Newtonian physics to the golf swing isn’t correct, or that the practical application side of it that I’ve created isn’t as useful as some other form of analysis? Sure they could. I welcome the discussion. Dr. Nesbit’s research goes beyond golf and his distinguished career and body of work is by far the most referenced by other golf researchers. And over the last two years, the research we’ve been doing using Jacobs 3D will be the basis of the next generation of peer-reviewed scholarly

papers Dr. Nesbit will be publishing. Top-shelf academic credentials are nice, but plenty of people want to see proof out in the real world. They want to see players using this information to play better. It happens every day on my lesson tee, for the professionals, top amateurs, firemen and accountants who come for lessons. I am excited to share with you some of the results of all that study. My friend Matthew Rudy (the ghosting editor of this book) always teased me about how annoyed I got at his efforts to make the material in the first Elements book simple and relatable for most players. Looking back, I have to agree that there was a need for a foundational book introducing everyone to the terminology and underpinnings of an unconstrained convention. I’m a collector of golf history, and on the shelves of my office are books written by the giants of golf—from Willie Park Jr., Sir Walter Simpson, Horace Hutchinson, James Taylor, Bobby Jones, Abe Mitchell, Sam Snead and hundreds more. I have been driven by all of their hard work and passion to try to keep moving the ball—to do my part to solve the search for a perfect golf swing. I hope this book helps you make your own leap.

Michael Jacobs Top 50 Best Golf Teachers in America -Golf Digest Top 100 Teachers in America -Golf Magazine

Introduction

CHAPTER

ONE

KINEMATIC AND KINETIC CLASSROOM In the elementary edition of this series, we started the book with a simple anecdote about a NASCAR race that illustrates the difference between what you can see with your eyes and what is actually happening behind the scenes. That same racing analogy is a good one to start off the master edition of this project. When you watch cars speeding around a big oval track, you see some of them going faster, some slower and some coming into the pits for more fuel or different tires. In a crash, cars start bouncing off each other (and the walls), and they come to a stop—usually after sliding and rotating around. What you see with your eyes—the changing position of the cars relative to each other and relative to the track—are kinematics. You’re seeing the end result of the forces and torques at work within the engines of the cars - the kinetics. In the world of golf swings, you can watch somebody move the club (or see a photo or video of a swing on TV, the Internet or Golf Digest article) and see that swings kinematics, or physical movement. Maybe a player lifts his or her hands

high in the air in the backswing, or makes a larger hip turn toward the target on the downswing relative to some other player. But seeing a swings physical properties doesn’t give you the full picture about how that player creates forces and torques in his or her swing—or how close that player is to optimizing those forces. A photograph of Rickie Fowler’s setup or top-of-the-backswing position doesn’t reveal why a 5-foot-8, 150-pound player can hit the ball farther than somebody 6-foot-4 and 240 pounds. Plenty of good analysts can pick up on some of the things a player like Fowler does to produce so much speed at his size—and some can take the next step and use the art of teaching to deliver the right bites of information and advice about the how and why of Fowler’s swing in a way that applies to the golfer in front of them. Still, the vast majority of that analysis is happening in the kinematic world— just the movement of the club and body—not the kinetics, or what is actually producing that motion.

The first chapter of the elementary edition gave a thorough introduction to the core components of this kinetic classroom— Force, Torque, Rotations: alpha, beta, and gamma. Taken together these elements describe the different kinds of forces and torques at work on the club during a swing. The first book was designed to provide an introduction to alpha, beta and gamma (along with other elements of the swing, like the hub path and relative swing plane), so that swing enthusiasts could see the framework that underpins the Jacobs 3D convention and get used to thinking about swings in this new language. Here, we’re going to go deeper into these elements and discuss how they actually work together to produce productive (and not-so-productive) swings. After a few months of studying the elementary edition of this book, you know the basics. Now, it’s time to dive into the entire Jacobs 3D and Dr. Steven Nesbit Convention.

Chapter One

measured. At the heart of the convention Steve first developed for his golf projects—and greatly expanded to create Jacobs 3D—was his background in robotics. Now, almost 30 years later, we’ve developed software that not only examines what the club’s experience is during a swing, but also offers a full analysis of 17 body segments and how they contribute to the production of forces and torques in the swing. (You’ll be seeing and hearing plenty about Alpha Man in the future.) Words like force, torque, alpha, beta, gamma, angular response, moment of inertia, center of mass, quivers—just to name a few—have become staples in the vocabulary of swing kinetics since the Fundamental edition was published. Here, I’m going to expand on some of these terms and use them to explain the equations of motion as it relates to the golf club’s movement. Let’s start by setting the atmosphere for the dynamic equations of motion. We’ll begin with what’s called an “inertial reference frame.”

The Framework FIGURE 1

The “origin story” behind the force analysis program I created with Dr. Nesbit has been welltold, but I’ll start with a brief summary if this is new to you—because it’s important to understand where Jacobs 3D came from to see why it’s so effective at helping us understand what’s really happening in the swing. In the early 1990s, Steve designed a convention to thoroughly analyze the inputs and loads applied to the golf club by a player—a story he reminisced about in the foreword of the first Elements book. Through the course of three decades of research and study, he has both uncovered previously unexplored branches of mechanics that explain many of the nuances you find in various golf swings and he has transformed how the USGA approaches regulating the sport. In the early 1990s at the USGA, Steve helped them determine what part of driving distance was being provided by the player and what part was coming from the club itself—and helped the association come up with a standard by which drivers are

An inertial reference frame is a fixed location from where we can watch the club move through three-dimensional space. The inertial frame in a 3D analysis is defined by the X, Y and Z coordinates. In Fig. 1, notice how the X, Y and Z coordinates are fixed to the ground. (You can also see how my Jacobs 3D logo was derived—inspired by this set of coordinates.)

Chapter One

Mass: Amount of matter in an object, and a measure of its inertia. Inertia: Tendency of an object to resist acceleration (a change of state in its motion).

Mass is often confused with weight, but those two things aren’t the same. Mass is measured in kilograms, while weight is measured in newtons because the force of gravity is involved. If you and I are standing on Earth, our mass is the same as it would be if we were standing on Mars—but our weight would be different in each place because of the change in the force of gravity.

“We adopt the philosophy that somewhere there is a universe coordinate system to which everything we discuss can be referenced. We will describe all positions and orientations with respect to the universe coordinate system or with respect to other Cartesian coordinate systems which are or could be defined relative to the universe system.”

Center of mass: The point in a body or system of bodies at which the whole mass can be considered as concentrated.

John J. Craig - Intro to Robotics (1955) Once we have our universe set, we can start to build the golf club model. Let’s first examine the properties of the golf club.

FIGURE 2

Identifying and understanding where the center of mass of club is and how it responds is a fundamental part of club kinetics. Throughout this book, you’ll see the center of mass of the golf club depicted by an orange ball. To get a quick understanding of where it is, hold your finger out and balance the club so that it doesn’t fall one way or the other (figure 2). Because there is a considerable amount of mass in the clubhead, the actual center of mass of the entire club is NOT on the club. The center of mass is in space on that vertical line down from the balance point of the shaft. Fig. 2 displays the approximate mass center of the club and the human body in a standard anatomical position.

Chapter One

can yaw (alpha), pitch (beta) and roll (gamma). One of the most powerful visual reminders of these planes of rotation comes from using a model airplane. I have a foam one I use when students and other teachers come to the studio for golf lessons. In Figs. 4 and 5, you can see the alpha, beta and gamma axes and how they would correspond to the way an airplane would move in the air. Alpha

Gamma

FIGURE 3

Beta

Once you locate the club’s mass center, you will need to take yet another coordinate system and embed it directly into that mass center. In order to differentiate between this new coordinate system and the inertial frame, a lower case x, y, and z is used to depict the coordinates in the mass center frame. Since in our convention we replace the x, y, and z with alpha, beta, and gamma we will embed a lowercase a, b, and g into the mass center (figure 3). The three planes of rotation of the club are defined using the a-b-g coordinate system embedded into the mass center of the club. The club

When the airplane is yawing from side to side (about the red axis), it is moving in alpha rotation. If you’re flying and the pilot stays at the same altitude but turns the plane left or right, you’re experiencing that alpha rotation. If the plane changes pitch by nosing up or nosing down, you’re experiencing beta rotation (about the blue axis). Gamma rotation (about the green axis) on a plane wouldn’t be so fun, but it would look like the plane is twisting in a barrel roll or corkscrew— like something out of the Blue Angels.

FIGURE 4

FIGURE 5