As different as serves, volleys, groundstrokes, lobs, overheads and drop shots may look, they are all means to the same end - to hit the ball over the net and into the box as far away from your opponent as possible. We would also like to put as much unpleasant "stuff" (spin, depth, pace, high or low bounce) on the ball as we can - anything that will frustrate and infuriate our opponent. The tool we have to work with is a high tech, carbon fiber, perfectly balanced weapon of war.

The Goals and objectives of all tennis strokes include the following:

Tennis Good

1. Return the ball to the opponent's court safely inbounds.
   • On this all depends. The preceding is pointless without achieving this so...
     • There is no negotiation with this point.  You NEVER tolerate lower percentage on a shot to achieve power, spin or placement. Not never! On the other hand...
     • Perfect consistency is impossible, so the trick is to manage your percentages.
2. Confound, confuse and contort your opponent with:
   • Placement (to forehand, backhand, behind your opponent - NOT at the lines.
   • Spin (topspin to send the ball high, slice to keep it low, and side-spin to drive them crazy. In this context effective spin is called "weight" as in "Wow, she hits a heavy ball!"
   • Depth as defined by where the opponent has to stand to address the ball, not where it bounces. A heavy, hard topspin on the service line is a deep ball while a floaty slice that drops 3 feet inside the baseline is nothing but a short approach about to be transformed into a fuzz sandwich for the approacher. Hitting deep means hitting a solid ball with pace and lots of spin halfway between the service and baselines for consistency.
3. Have fun!
   • This can be challenging if your are constantly mortified by your own unconscionable errors, but then that is the point of all this jibber-jabber. If you can't get your game to the point that egregious errors are the jocular exception instead of the cruel rule, then why hurt yourself? Take up running instead.

Tennis is a blast - full of drama and comedy.  You don't have to be top ten in the world to truly experience and enjoy it. If you know tennis and know yourself you can perform well beyond the limits of your God-given inabilities.

The Four Fundamental Objectives

An effective strike of the ball must result in four basic outcomes:

The Four Fundamental Objectives

1. Address the ball.
   • get the ball into the strings
2. Take control.
   • change the direction of the ball
3. Add pace.
   • at least enough to get it over the net
4. Add spin.
   • reshape the flight path of the ball
   • make the ball bounce funny

The trick is that you have accomplish all of these with a single swing and in a very narrow window of time - the five milliseconds that the racket is in contact with the ball. Moreover each these effects requires either a force or a racket movement in a unique direction (see figure below). If there is one reason why talent matters, it is this seemingly impossible task.

Moment of Contact

We develop the stroke foundation from the inside out beginning at the instant in time when the racket makes contact with the ball. The interaction between the racket and ball lasts only about five thousanths (.005) of a second during which time a racket travelling 90 feet per second moves about six inches. In that brief moment, you need to deliver pace, impart spin and, most importantly, take directional control of the ball. Let that sink in for just one second.....

Time's up! Now reflect that that one second is fully 20 times longer than the time you have to influence the flight of the ball. It is plainly amazing that all of that "influence" can even be transferred to the ball in five milliseconds but it is downright absurd to believe that during that brief moment your mind can do any of the astounding processing required to calculate just how hard, spinny, up, down, left or right your ball needs to be to reach your intended target. It may therefore not surprise you to learn that your contribution to the stroke itself is finished long before the moment of contact.

When to Take Control

One pernicious black pearl we were all taught in the '70s was "For control you must stroke through the ball low-to-high towards your intended target!" implying that the flight path of the racket completely determines the flight path of the ball. Obviously, nothing you do during the follow-through phase of the stroke can directly affect the flight of the ball since the ball is already on its way. The importance of the follow through is as a report on what happens prior to the moment of contact. So since there is nothing useful that you can accomplish during the follow through or the .005 second moment of contact, you must take control of the ball much earlier in the stroke. How about taking control of the ball just before you make contact, in the 20 or so milliseconds leading up to the strike? You could make sure that the flight path of the racket head corresponds exactly with the flight path you intend for the ball. Now your talking! Some players still hit the ball that way, and it was ubiquitous back in the '70s. The problem with that plan is that we also have to address the ball and add spin. These require the racket head to follow a path to the ball that is expressly not the same as the ball's intended flight path. In fact, the racket head must travel across the incoming flight path of the ball if you want to create spin. As we shall see, the only safe time to create control is early in the backswing, before the racket starts to move forward. Take another second to think about that. Early in the backswing, the racket is not going to be pointing anywhere near the opposite court much less pointing at some small target that you believe you need to hit. It is a fact that the pros create most of their spin and all of their when the racket is still behind their bodies. When the racket finally begins to move forward towards the ball, they have already done all they can do to assure that the ball will land where they want it to land.

From the Ground Up

Now let us "follow the force" from the ground up to the ball. You can think of a force as a means of transferring energy and momentum from one object to another. The medium through which this force travels through the body has been erroneously called a "kinetic chain" and has been likened to a series of gears and levers represented by your bones and joints. In actuality, the medium in which the force travels is your muscle, and the form of the force is a wave of energy that usually begins with a "push-off" against the ground by one or more of your feet. Your skeleton is simply a framework on which your muscles hang.

Muscles are less like motors than they are like adjustable springs. Like springs they can absorb energy, hold it for a time, then deliver it back to the source or pass it forward. They cannot create momentum, but they can steal momentum from the earth and carry it to the ball. If your driving foot is not tightly "stuck" to the ground (by friction), you will not be able to grab much momentum from the ground without slipping. Great traction requires great footwork which means creating dynamic balance.

When we who are less athletically favored think of being on balance, we normally think of standing on two feet, shoulder width apart, with our center of gravity halfway between them. This state is called static balance, and it is useless in sports. In sports you are always in motion, so your center of gravity is all over the place. When you are in dynamic balance, the center of gravity becomes moot. Dynamic balance depends on constant motion and acceleration; either traveling in a circle or shifting your weight from one foot to the other. When you are constantly shifting your body weight from one foot to the other, the amount of force pressing each foot to the court surface is up to 4 times your total body weight. The pressure of your foot against the court surface creates enormous friction. I call this phenomenon "sticky feet" and it is how A-players harvest so much momentum from the earth to deliver to the ball. In dynamic balance, the quadriceps muscle is in complete control of the relationship of the body relative to the ground resulting in a perfect a perfect sense of stability and well being, provided you keep your knees bent at all times. If you lock your knees, even for an instant, you lose all dynamic balance along with all of the power, agility, control, and grace that goes with it.

Another advantage of dynamic balance is that it keeps your brain from messing up your strokes. You must always satisfy the part of your brain tasked with the important job of keeping your noggin from smashing into the asphalt. If you fall out of dynamic balance into static balance, even for a few seconds, your brain will be forced to contort your upper body to control the position of your center of gravity. The brain's interference will disrupt the flow of any stroke. In dynamic balance, the location of the center of gravity is no longer a concern for your brain. Achieving dynamic balance is the first and most essential step in any stroke.

Catching the Wave

Pushing off from the ground initially moves the lower carriage (legs and hips) forward, upward and around. The upper body lags behind for a few milliseconds for two reasons; the inertia of the upper body and the stretchability (compliance) of the trunk and spine (core) muscles. That stretchability is not infinite, however, so as the core muscles become taught the shoulders begin to move in the same direction as the legs and hips just as the legs and hips are slowing down. Meanwhile, the racket arm and racket are lagging behind the upper body due to their inertia and the stretchability of their muscles. All this lagging results in a wave of power that propagates through the body ultimately ending up being transferred to the ball by the racket.

"So what?" you demand impatiently. The wave concept is important because if, instead, you believe you are a bunch of mechanical levers, each one contributing to power or control, you timing will never be correct. Too many players push off of their back foot while they are striking the ball. They do this because they envision a direct link between the push-off, hip rotation, shoulder rotation, arm swing, and wrist snap. In fact, you need to push off of your back foot long before the power of that move is reflected in the strike of the ball (see animation below). Actually, in the topspin forehand, you need to have already started pushing back against the stroke with your front foot even as you accelerate the racket forward. This syncopation is necessary because of the time it takes for the power wave from your feet to reach the wrist. For those of us in the shallow end of the athletic gene pool, learning to synchronize our hands and feet in tennis properly is tough enough without struggling against a distorted view of reality.

Harvesting the Power Wave

Once you have fully accepted the wave concept, you can start to take advantage of it to improve your control and consistency. As the power wave passes through your shoulders and forearms, you can tap into its energy to accomplish all of the objectives listed above, namely pace, direction control, and spin.

Some of the energy is invested in racket head speed that will create pace and basic spin. The rest you can convert into stored force that is released directly into the ball imposing directional control and additional spin. When you apply force directly to the ball during the moment of contact you change the direction of the ball in the direction of that force - a phenomenon called impulse. The effect of impulse is different from the effect of racket head speed. Racket head speed does not determine a ball's direction, it simply turns the ball around and adds pace. If you swing at a volley coming down into your strike zone the ball will bounce back toward your opponent court but continue moving downward into the net. Increasing or decreasing racket head speed cannot prevent this outcome. Conversely, impulse redirects the ball in the direction of the force you are applying at the moment of contact. Impulse does add pace, but it is primarily the only reliable source of control.

The Unit Turn and the Pose

The unit turn begins the stroke. It is a brief, violent move designed to get the shoulders and hips turned, feet positioned and to establish dynamic balance. It is not the backswing. The overall purpose of the unit turn is to take you from the ready position to the pose as quickly as possible so that the stroke is not rushed.

The pose is an easy-to-remember position of the feet, shoulders, and arms and racket that serves as the entry point into the lock and load sequence. This body position, which is unique to each stroke, is designed to melt into the lock phase and trigger the thalamus to start playing back the stroke.

Storing Force - Lock and Load

The the tool you use to force the ball to follow the flight path or your choosing is force stored in the muscles of the in the forarm during the backswing then released at the moment of contact. This force storage and release are commonly referred to as 'wrist snap,' loosely named for the feeling of a sudden acceleration of the racket head thaat actually happens after the ball has left the strings. Wrist snap has been widely taught as a method for adding pace to the ball, but it is much more important than that: it is the ultimate source of control and consistency in all strokes, whether you are hitting hard or soft or with slice, topspin, side-spin or no spin. I call the process of storing baLL-control forces the lock and load.

The lock begins after establishment of the pose. You start the lock by completely relaxing the hitting arm and shoulder. In the topspin forehand, this involves letting the wrist and racket fall out of the pose under gravity. The first phase of the power wave is to push back away from the ball with the feet that starts a small reverse-rotation of the shoulders, dragging the hitting arm and racket back away from the ball. This reverse-movement of the racket is the lock or 'backswing proper'. At the end of the reverse-rotation, the inertia is carrying the racket head towards the back fence. The agonist (forward) muscles in t he forearm reflexively tighten in response to this motion, essentially catching the racket and thereby setting the tonus or tension of your forearm muscles. Forearm tone tightens the forearm muscle's 'springs,' getting them ready to be stretch-shortened wehn the shoulders reverse thier rotation and begin to drag the racket forward. This change in direction represents the positive 'crest' of the power wave that is begun wehn the you "step into the ball". Critical to an effective lock are the position and rotation of the upper arm and forearm, the velocity of the racket and the tone of the forearm muscles that will store-then-deliver control and spin forces to the ball, the so-called 'agonist' muscles. You harvest the stored force itself from the positive crest of the power wave during the " load" phase of the stroke. The load results from the sudden forward rotation of the shoulders as the power wave passes through them and down the arm. The arm and wrist accelerate forward leaving the racket head behind owing to its inertia which can be upwards of 15 pounds. The racket changes orientation: from a tiny layback in the volley, to a complete flip end-over-end in the serve and topspin forehand. This forcible change in orientation winds up and stretches the already shortened forehand agonist muscles. by the end of the load, you will have stored forces in your forearm muscles that will ultimately be responsible for all of the control of the stroke. Except for the aformentioned tonus in the agonist muscles of the forearm, your upper body must be relaxed going into the load. If you are still tense during the lock and load phases, the stored force will be stunted and useless.

In the Federer-style topspin forehand, the pose comprises a semi-open stance, shoulders turned, elbow bent and somewhat away from the body and a vertical, pronated racket. As the first phase of the power wave approaches, the hitting arm is released to gravity and begins to drop out of the pose describing a gentle clockwise arc. The initial trough of the power wave hits as the racket falls, counter-rotating the shoulders and causing the wrist to bull the racket away from the ball slightly. The drop and reverse-rotation comprise the lock or (the "backswing proper"). At the end of the reverse-rotation the inertia tends to throw the racket head back. The forearm agonist muscles, in this case, the flexor-pronators, stiffen to resist the momentum of the racket but result in very little net motion of the racket since the racket head's momentum perfectly counters the force, so the flexor-pronator muscles are shortened internally and ready to be stretched. I call getting the flexor-pronator muscles ready to be stretched "setting the tone" of the agonist muscles, and it is, regrettably, completely under the player's control and can make or break the strike. Too loose and the stroke is sloppy, too tight and it is stiff. Either way you will not properly stretch-shorten the muscles and there will be no control.

Immediately after the completion of the lock, the load begins as the positive (forward) peak of the power wave arrives, causing the trunk and shoulders to rotate into the stroke, dragging the hitting arm and racket violently behind them. Because of its inertia the racket lags behind the wrist as the rest of the arm is dragged forward by the shoulder. The difference in direction of force between its but and head flips the racket end-to-end and snaps open its face, which ultimatly parallels the side fence. This violent change in orientation "winds up" the forearm muscles, stretching the flexor-pronator muscles and thereby storing both forward and rotational force. At the start of the topspin forhand load phase the head of the racket is below the wrist, so topspin rotational force will be stored. If the racket head is above the wrist at the start of the load, as in the volley and approach shot, then a slice inducing force will be stored. Preparation for storage of the directional control force is more complex, but the goal is simple; redirect the ball to a point 12-24 inches above the net. You don't need to figure out which pre-load arm position results in the desired post-strike ball trajectory. Your brain is more than capable of making that connection though practice and observation. Your responsability is to make sure you store enough control force in your forearm muscles to make that association relevant.

During the lag phase that follows the load, constant acceleration keeps the racket back behind the wrist and bottles up the muscular forces stored in the forearm. Immediately prior to the moment of contact, the negative third phase of the power wave hits. This second trough of the power wave opposes the forward motion of the hips and shoulders, decreasing or eliminating acceleration at the wrist and releasing the stored forces. This release of pent-up energy is the "explode". A few milliseconds later in the stroke, when the racket face finally makes contact with the ball, the entire energy wave has passed and what is left is the kinetic energy and momentum of the racket due to "racket head speed" and the stored linear and rotational forces in the forearm muscles. It is these strored forces which magically transfers control and spin into the ball via Impulse. I say "magically" not to be dramatic, but almost literally; because the stored force in the muscle does not reveal itself through any overt motion of the racket until the follow-through, long after the ball has already left the strings!

Cut Like a Saber, Explode Like a Bomb and Collapse Like a Marionette

So what prevents the stretch-shortening control-and-spin forces from dissipating between the end of the load phase and the moment of contact? Containing the stored forces is one function of the lag phase. During the lag phase, racket is trailing behind the wrist, the butt end of the racket pointing more or less in the direction of the oncoming ball. The phrase "more or less" sounds pretty mushy, but, in fact, it is quite precise. At the start of the Lag phase, it should feel like the butt end of the racket is tracking towards the ball in a perfect bee-line. That is a convenient illusion. Actually, since your hips and shoulders are rotating, the hitting hand and the racket are orbiting your body, not traveling in a beeline. The stroke is reminiscent of a sabre cut, which is less of a 'hack into' than it is a 'slice across'. Otherwise, you would be obliged to bunt the ball with the butt of your racket. The illusion that you are tracking the ball with the butt of the racket is so vital that teaching pros at the Windridge Tennis and Sports Camps in the 70's based their entire forehand teachings on the concept of the "flashlight forehand"; pretending the handle of your racket is a flashlight and shining it on the ball as you bring the racket forward. The flashlight forehand is the essence of 'lagging' the racket behind the wrist. (Actually, even in the forehand a "butt-light" would probably never shine directly on the ball and even if it did it would very briefly sweep across it, but the teaching method was very effective, and for years graduates of the Windridge camps seemed to dominate high school level tennis in the Northeast.) I believe the flashlight forehand teaching technique was effective because lagging is unnatural, and anything that gets an elite athlete to lag the racket will open the door to a full, modern topspin forehand with optimum control and amazing spin. Regrettably, I must exempt you and me from the moniker 'elite athlete' and require that we know more, so read on!

During the Lag phase the arm is being accelerated forward by the shoulder and is dragging the racket behind it, maintaining the stored force in the arm. There is a dynamic balance between the acceleration of the shoulder-arm unit pulling the racket towards the ball versus the inertia of the wrist-racket unit resisting being pulled. Just before the moment of contact between strings and ball, the power wave reverses, and the upper body stops accelerating. The stored force of the forearm, upper arm and shoulder muscles are then released directly into the ball as linear and rotational impulse; imparting control and spin to the ball. This transfer is invisible and thus seems 'magical.' Ideally, the racket shouldn't immediately change its velocity or direction as a result of the release of the stored forces. Instead, the forces pushe the strings into the ball for the five milliseconds that the ball is in contact with the strings. That is the definition of impulse: momentum delivered = force applied X duration of application. Unlike racket head speed, impulse's effect on the ball is highly directional and thus has the power to redirect the ball in the direction of the applied force. Immediately following the moment of contact the arm often seems to collapse into a tangled knot as the linear and rotational muscular tension, held at bay during the lag phase, is finally converted into visible racket head acceleration and rotation. Since the forces that cause this strange, contorted follow through are not manifest before the ball has gone on its way, tennis instructors have largely neglected these fundamental forces. Advanced stroking could only be learned or taught through close observation and mimicry of very talented athletes by other very talented athletes.

Unfortunately the mimicry method only works for natural athletes, because as problems arise with these strokes, as they inevitably do with any complex choreography, the talented can find their way back into the stroke through their God-given superior muscle memory and kinesthetic grace, while the rest of us just flounder and fume. If, however, you know what you are doing - if you know why the whole thing works- you will find that the way back to the center is always open to you.

Putting it All Together

Every stroke in tennis rests on the same basic foundation. For every stroke, from the serve to the drop shot, that foundation is built, from the ground up, of the same basic components:

Basic Components of All Tennis Strokes

1. Dynamic Balance
2. The Pose
   • or pause, or "unit turn"
3. The Lock
   • or backswing proper
4. The Load
   • or transition to forward swing
5. The Lag
   • an endcap-first drag toward the ball.
6. An Explosion
   • just before the moment of contact
   • triggered by terminating the acceleration phase
   • it must be active: pushing back vs stopping pushing
7. A follow-through to tell us how all the rest of it went.

Although these seven phases are distinct conceptually, in reality, they tend to overlap one another. The lag phase, for example, actually includes the last half of the load phase and much of the Explode phase, yet it is imperative to think of them as a sequence of distinct events. The lag phase is quite violent and active, while the explode phase, despite its name, requires complete relaxation. Each stage has its own set of goals and requirements distinct from the others yet they all comprise a single, smooth, unbroken motion. Each phase begins before the end of the preceding 'sphase. In that way, they have more in common with a Bach fugue than a pop ditty.

Dynamic Balance

Dynamic balance is the bedrock of all sports - it is the foundation of the foundation. As such the first thing to ask yourself when things go awry with your tennis game is "Am I on balance?" To understand the symptoms and signs of not being on balance, you need to understand what being on balance does for your tennis game:

Functions of Dynamic Balance

1. Stabilize the upper body
   • Satisfy the cerebellum - keep it from using the upper body to maintain balance.
   • Consistent ball toss on the serve.
   • Allow solid contact between a moving ball and a moving racket.
2. Transfer momentum from the earth to the ball.
   • Traction to "push off" into the ball.
3. Optimize movement to the ball and back to the ready position.

Among the signs and symptoms of imbalance are:

You may be out of balance if...

• Your service toss is subtly inconsistent.
• A piteous lack of power on volleys or groundstrokes.
• You find yourself freezing like a deer in the headlights.
• You are victimized by bizarre, inexplicable errors that come an go.
• You are staggering around like a zombie, missing everything..
• You are dancing on your heels (as opposed to the balls of your feet).
• You take your first step to the ball after it is already by you.

The key observation (sign) that identifies poor footwork is that you are not running and hitting with your weight fully on the balls of your feet. It is fascinating to me that we have all been told that we need to "get up on our toes" to play good tennis - at least that is what I was incessantly told as an awkward 13-year-old with size 13 feet. If one tries to do that as a first course to correct a problem with footwork, it is always an unqualified disaster. Standing with your weight on the balls of your feet when you are in static balance (e.g., weight distributed between both feet, center of gravity between the feet, shuffling gate, knees locked...) feels really, really unstable and out of balance ... because it is.

In static balance you need the muscles in your calf to constantly adjust the weight between heel and toe to keep you from doing a face plant. Consequently, since I lived in a static-balance world, every time I was told to "get up on the balls of my feet" - excellent advice in theory - I lasted about 5 minutes stumbling around before I gave up on it and re-engaged my heels. I imagine that talented people given the same advice naturally bend their knees, start bouncing their weight from one foot to the other and huzzah! They find themselves magically in a new state of balance - dynamic balance - without really knowing what it is or what it is called.

If you recognize any of the preceding signs or symptoms then you may need a bit more information on how to achieve and stay in dynamic balance. Luckily, though not obvious or even natural for most of us, there are no real barriers to entry to the realm of dynamic balance. The keys are these:

How to achieve dynamic balance:

1. All weight on one foot at a time at all times.
   • Shift all bodyweight weight from one foot to the other:
     • - even when standing still waiting for the ball.
     • - even while hitting the ball (this is why we "step into the ball")
     • - even before, during and after the ball toss in the serve
     • Listen for the chirping of your souls on the court. If it stops you are in trouble.
2. Knees bent always.
   • If you stand up you go down
3. Be in shape.
   • strong legs
   • good endurance
   • optimal body weight
   • no illness (viral or otherwise), dehydration, good nutrition

Thats it! It's not any more complicated than that. You don't even have to think about standing on the balls of your feet because it happens automagically when you achieve dynamic balance!

One important addition to the preceding list is that when you are flying through the air, you are actually in dynamic balance. Flying is a special form of dynamic balance that often occurs during the strike of the serve and during powerful groundstrokes. In that state, your brain is completely satisfied with the situation and is not even thinking about the attitude of your upper carriage. Obviously, you need to be in a more traditional ground-based dynamic balance just before leaping into the air so you can effectively transfer momentum from the earth and carry it into the jump.

The Pose

The pose is the attitude of the feet, hips, shoulders, arms, and racket at the end of the unit turn just before the start of the backswing proper (lock phase). As such it is less of a move than a goal, but one of the most important goals in tennis. The pose is at the heart of every stroke and in many ways defines each stroke. Some of the poses have specific names, others just vague descriptions and for that reason, the pose has been often ignored as "flourish" or decoration and considered optional. It is not optional!

The poses are these (I have named some of them myself for convenience):

Poses

1. Trophy pose (Serve, Overhead Smash)
2. Recoil in Horror pose (topspin forehand)
3. Frisbee pose (topspin one-handed backhand)
4. Unit Turn pose (2 handed backhand)
5. Karate Chop pose (forehand and backhand slice, volley, drop)

There are two main purposes of the pose. One relates to the "physics" in psychophysics, the other to the "psycho" part. The physics purpose is difficult to explain because the shape of each pose - high or low elbow, racket head above or below, behind or in front of the wrist, etc. - is a preparation for a preparation. The pose prepares the body, arm, and racket for the lock phase which is, in turn, a preparation for the load phase. From the pose through the load the racket goes through several gyrations on its way to aligning itself for proper contact with the ball. Suffice it to say that the pose puts the racket, forearm, elbow, and shoulder into a position to fall gracefully through the lock into the massive positive energy wave coming from the legs. If the pose is wrong, the lock will fail, and the forces stored during the load phase will be corrupted or nonexistent.

The "psycho" purpose of the pose is a bit simpler. If you put your body into a reliable, unique, consistent pose before addressing the ball, you help the brain identify which "dance move" it is about to perform. The thalamus, which is responsible for storing, initiating and moderating complex, whole-body actions, relies on external and internal stimuli to identify which action to "playback". Identifying the correct recording for the thalamus is likely the neurological reason for rituals the pros use before serving. Pros are just as obsessive about their poses on overheads, groundstrokes, and volleys (when they have the time to set up). Watch them and then judge for yourself whether those preparations are more likely to represent mere flourish or an essential component of a successful stroke.

The first physics function of the pose is to optimize the generation of the power wave. One of the key components of the power wave is momentum. Momentum in tennis cannot be created out of whole cloth. It must either be stolen from the earth or derived from counter-rotation Stealing it is the most efficient and powerful method, but it requires that the feet be firmly anchored to the earth. That, in turn, requires that we be in dynamic balance. Also, our feet and shoulders need to be in the right orientation relative to the baseline for the power wave to be usable; a quite closed (back turned to the opponent) stance for the backhand for example. Failing both of these there will be no usable momentum and thus no power generated by the feet.

Alternatively momentum can be cobbled together by counter-rotation the process of moving two body parts in opposition to one another. - requires the co-operation of either the back leg or the non-hitting hand, meaning that they need to be properly positioned in the pose as well.

The second physics function of the Pose is to prepare to properly transmute power that comes up from the legs into stored force in the shoulders and forearms through stretch-shortening of the muscles. The pose is a mechanical contrivance - a magical stance that ensures that when the twisting, thrusting power of the trunk is delivered into the shoulders - driving them first back then forward and around - that when the racket meets the ball hundreds of milliseconds later the desired spin and directional impulse is delivered into the ball. The how and why of any given pose is a little tricky since it occurs even before the backswing proper and yet has effects that carry through the moment of contact with the ball. The best example of this is the forehand topspin stroke vs. the forehand slice. In both the topspin and slice Poses, the racket head is above and in front of the wrist with the non-hitting hand on the throat of the racket. For the topspin, the hitting elbow is up (shoulder pronated) while for the slice it is down (shoulder supinated). The difference is subtle but important as it has vast implications on what comes after. As you might expect the one-handed backhand poses are opposite; elbow up for the slice and down for the topspin. If you are hitting a shot with the wrong pose, you will fail. If you are hitting with an inconsistent pose, you will fail to be consistent.

The Lock Phase

The lock is the move that prepares the hitting arm and racket for the arrival of the power wave sweeping through the upper body. The following must be accomplished by the lock if the forces needed to redirect the ball and add spin to it are to be "loaded" into the ball during the load phase:

Objectives of the Lock Phase

1. get the racket moving
   • away from the ball (so back)
   • using gravity (so down)
   • smoothly (so in a circle)
2. relax the hitting arm and wrist
   • to prepare the muscles for stretch-shortening
3. simulate the follow through
   • pronate for pronation force
   • supinate for supination force
   • forward for forward force
4. may be subtle in some strokes but no less important!
   • slices
   • volley
   • one handed backhand topspin
   • short strokes

Things that move, want to move. Things that stick, want to stick. That is mechanics in a nutshell. The phrase "...get it started..." is all you need to understand to get that #1 above is important. A little trickier is the direction - down and back. The first move in tennis is always opposite. If you want to go left you first have to jump right to set your feet for the leftward push-off.

The first step in a high overhead is always forward towards the net. Similarly, the first direction for the hitting arm and racket is away from the ball. The back then forth theme relates to the concept of wave motion in a tennis stroke. Waves are back then forth. If you are not already back, how can you have a strong forth? When the peak of the wave hits it is going to be all forward towards the ball, so you need your hitting arm to be moving back when it hits. At the moment of contact, you are going to be moving your hitting arm low to high. This low-to-high rule is as true for topspin as under-spin, volley, serve, groundstroke, etc. I am not sure why other than the ubiquitous presence of gravity which we must overcome to get the ball over the net. Anyway, the first move is always down and back, but wait! #2 - relax the hitting arm and wrist - is more important than #1. If your arm isn't relaxed, you cannot store control and spin force in your muscles, and you are done before you start. You will simply club the ball with your stiff-armed - well - club. The need for relaxation is why it is essential to use gravity to get the racket moving, not your muscles. Taking advantage of gravity to get the arm moving into the lock is why all of the poses are high racket head poses. Your arm should fall effortlessly and gracefully, down and back, into the best position of shoulder, elbow, wrist, and racket to take advantage of the power wave that is about to hit. Relaxation is why I make such a big deal about separating the early preparation of all strokes into the quick-and-dirty unit turn followed by the nearly inert pose and finally the lock (or backswing proper). There is a lot to get done in the unit turn, so it has to be violently fast. There is no time to make it pretty, graceful or relaxed. The lock has to be all of those things, so it can't be violent. The most common mistake that even advanced players make is to conceptualize the entire backswing as one move from the ready position to the transition point when the racket starts to move forward. That way lies madness and death to control.

Finally there is #3, and I admit it is counterintuitive. Take the "pronation for pronation" part. If you need to store pronation force in the forearm and shoulder to add topspin to the forehand, you need the arm and forearm to be incomplete pronation at the end of the Lock phase when the power wave hits. To store the pronation force, the arm must first be "wound up" into forced supination during the load phase. The force that winds up the arm comes from the inertia of the racket resisting the forward acceleration provided by the shoulders as the power wave begins to rotate the upper body into the ball. To wind up the pronator muscles of the forearm the muscles must be near fully contracted so they can be stretch-shortened, and that means the arm has to be in pronation. At the end of the load phase and the beginning of the lag phase of the topspin forehand the arm is fully supinated and the pronator muscles at full stretch against their will. They will stay in that state until the end of the lag phase when the decreased acceleration of the shoulders (as the power wave reverses) suddenly makes the racket feel like its horizontal weight has suddenly dropped from twenty pounds to 10 ounces. At that moment, which is ideally the moment of contact, the stored pronation force is released. Now, the racket and arm are still in supination, and its position in supination is appropriate to address the ball in such a way that a freeze frame of the moment of contact looks like you are trying to hit the ball mostly flat. Immediately following the moment of contact, in the follow through, the arm, now unaffected by acceleration from the shoulders, snaps into a somewhat spastic looking knot that closely resembles the arm at the end of the Lock phase. That which was wound up unwinds. Comparing the topspin follow through of Federer (ugly) to Stan Smith (pretty) mirrors the amount of topspin each player can generate; Federer attains hundreds of rpm more topspin than Smith ever did.

Short Stroking

All of the above happens and is equally important on the shorter strokes such as volleys and slices and the one-handed topspin backhand, but they are not nearly as obvious as they would be in the longer strokes like the topspin forehand. By comparison, in the short strokes, the lag is eliminated, and the unit turn is shorter. That said, when you don't include a proper pose, lock, load and explode in your volley, you will suffer a tragic and mysterious loss of control. Short stroking is still stroking and if you don't "snap" your volley you have no reason to believe that you have any real idea where it is going.

The Load Phase

The load phase is the simplest to execute. If you are in a good position and relaxed at the end of the lock, you just go for it! A lot is happening in this phase; acceleration of the racket to speed, storage of control and spin forces and preparation for addressing of the ball. The load tends to be quick and a little violent but smooth if you are relaxed. You must expect and confirm that the racket snaps into something like its mirror-image orientation compared with its position at the end of the lock. During the dramatic topspin forehand load, the arm goes from fully pronated and racket head in front of and above the wrist to fully supinated with racket head behind and below the wrist. This transformation can be vastly more subtle in the short strokes like the volley. For the volley, the racket goes from slightly behind and above the wrist at the end of the lock to slightly more behind and less above the wrist by the end of the load. The difference in these two positions is minimal but important because, during that transition, control and spin forces are stored. In the serve the load phase starts halfway through the "pendulum" move of the racket behind the left shoulder (which comprises the lock or backswing proper of the serve). As the legs explode, and the shoulders roll pulling the hitting arm up to the ball, the racket's inertia pulls the arm into the most painful-looking position I can imagine behind the right shoulder: The forearm and shoulder are fully supinated, the elbow is bent 90 degrees and the upper arm is in line with the shoulder. The butt-end of the racket is pointing up to the point of contact ready for the lag phase carrying the racket up to meet the ball.

The load phase is easy: If you time the power wave accurately and complete the lock phase properly, the load just happens. Diagnosing failure to load is also pretty straightforward. No load = no snap, no spin and no evidence of stored force in the follow through.

The Lag Phase

Once the racket is comfortably tucked away behind the hand and wrist you can proceed to pull it into the ball. Actually, you pull the handle across the flight path of the ball, and that brings the racket face into intimate contact with it. It is during the lag phase that you develop racket head speed which contributes to both pace and spin, the proportion of each being dependent of the angle of attack of the racket relative to the desired flight path of the ball.

The usual way one gets in trouble with the lag phase is to push instead of pull. Pushing results from an attempt to catch up the racket head with the wrist and forcefully drive that 20 pound (inertial weight) racket head directly into the ball. That is not easy to do, and besides, it is a loose-loose proposition. If you fail to get the racket head around you will mis-hit the ball, usually catching it on the tip of the racket frame. I realize that you imagine yourself fully able to use your superior hand-eye coordination to address the ball directly thanks to your indomitable force of will and the superior muscular development of your 'guns.' You are sadly wrong about that. Instead, you need to understand the way the arm and racket orbit the body during the lag phase. Even in the volley, where the butt of the racket never actually points at the point of contact, you should aim the racket's handle, not it's face, at the ball. Trust that the face of the racket will come around to the ball without a shove from your 'guns.'

If, on the other hand, you do succeed in pushing the racket head into the ball, you will waste the control and spin forces you went to the trouble to store during the lock and load phases. If you want to redirect the ball to your target, as I would hope you do, then there can be no force on the racket at the moment of contact other than those stored forces. Any other force, especially a conscious effort to push the racket through the ball, will override the effects of the stored forces. The Lag Phase must end before contact as its ending is what releases those stored forces. After all, the acceleration of the lag phase is what keeps the stored forces stored until they are ready to be used. Just before you make contact with the ball, you have to relax and let go of the racket-arm complex. That releases stored control and spin forces and lets you dominate the ball.

The Length of the Lag Phase

The Explode Phase

As violent and active as this sounds, it is not something you do as much as it is something you stop doing; you suddenly stop accelerating the hitting arm and racket. You do this when the lag has brought the racket face to a point a few inches shy of the point of contact and a few milliseconds from the moment of contact. The racket has plenty of head speed directed both through the ball (for pace) and up (for topspin) or down (for underspin) but it is like a runaway freight train and offers to provide little or no control over the ball. When the acceleration starts to ebb and the racket instead of "weighing" 15 pounds now weighs less than 1 pound, the stored forces in the arm and forearm are suddenly released and start to accelerate the racket head along the desired flight path and rotate it in the direction of the desired spin. Before the racket can respond, however, it encounters the ball and immediately transfers most of the stored force into the ball, adding to the spin and especially the control over the ball's flight path.

Now if you forget to stop the rotation of your shoulders and "drive through" the ball, you won't release those forces until after the ball is gone and is on its way to wherever balls go when we have no control over them. Similarly, if you decelerate too early not only will the forces dissipate before they can affect the ball, but they will also affect the path of the racket head in a way that is unrecoverable, resulting in shanks, miss-hits or just driving the ball into the net. This need to precisely time the end of the lag is likely what the talented mean when they claim "My timing is way off today!"

Follow-Through

After the ball is gone you can do nothing to influence its destiny. The follow-through is therefore irrelevant, right? Wrong. The follow-through has a unique and important effect on the next shot and all subsequent shots. The follow-through is a direct result of all that comes before it in the stroke. It represents the visible expression of stored forces that were put away during the lock and load phases and carried to the ball in the lag Phase. If anything goes amiss during those processes, the follow-through will be "different". The differences will be pretty obvious if you don't interfere with the follow-through by tightening up.

From a pure feeling standpoint the follow-through is an expression of intent. For example, your intent to add topspin to the ball in the forehand is reflected in the extreme pronation seen in the follow-through. Therefore training yourself to maximize topspin on the forehand is a matter of trying different techniques to optimize the lock and load of a stroke and observing the result in the follow-through. Similarly during a match, if your balls are sailing long and the pronation is absent in the follow-through, you know immediately where the problem lies. The follow-through must be cultivated and closely monitored but not forced to be what it is not, for then its value as a diagnostic tool is lost.