| By Steven Kaplan

Traditionally, strokes are developed and corrected by haphazardly focusing on body movements, racket movements and ball and racket interactions. This approach is confusing, ineffective and needlessly complicated because it fails to address the kinetic chain of events that led to a successful stroke. I suggest a different paradigm for managing tennis stroke production corrections by explicitly comparing and integrating racket movements with running acceleration movements.

You can be a good player by expertly compensating for movement inefficiencies; however, to quickly and safely progress from good to great, you must use the best body parts as slings rather than as levers in kinesthetically correct sequences to maximize efficiency and produce power by making anatomy, gravity and momentum allies.
I have outlined 10 broad concepts in a linear order from the initiation of the stroke to its completion in the kinetic chain. Some of my descriptions deviate and conflict with common tennis corrections, since much instruction uses trigger words as a conceptual shorthand. Unfortunately, this practice is misleading and imprecise.

One of my least favorite trigger expressions, for example, is to correct a hit using the term "late" since this incorrectly refers to time, and often, the intended contact correction was "behind" which reflects mechanical disadvantage and not timing. Indeed, players and coaches are frustrated by seeing strokes broken down step by step because the descriptions that accompany the pictures are crude observations masquerading as analysis. When I watch Andy Roddick ready himself to hit a powerful serve and I read "here is his loading phase," it helps me to hit a serve 140 mph about as much as knowing that E=mc2 means that time and space are relative. These concepts are profound, but if they were practical and useful, then I would be a multiple Grand Slam champion with a sizeable portfolio of Apple stock and real estate in the West Village gathered while time traveling.

Stroke mechanics simplified

1. Explosion, not progressive acceleration
When a rocket blasts off from its launching pad, it accelerates from the thrust of its engines. Tennis movements are not these kinds of progressive stage accelerations; rather, they are singular explosions much like a bullet fired from a gun with linear hip extension providing the force from the ground up. Rotational unloading of the hips, torso and arm are the result of initial acceleration. Added rotational emphasis is not useful since it relies on external force which results in body instability and stroke inconsistency. Useful racket speed from powerful movements is described in Newton’s third law of "action-reaction." It's not how fast you move, but how much force you push into the ground. Power results in speed, but speed does not produce power.

2. Hip lift and extension
Great mechanics transfer energy and move it in the right direction. Sit back to flex your hips and you are ready to extend and lift from loaded posterior muscles rather than the quadriceps. The quadriceps are not made to drive your body up; rather, they flex and extend your foot back. Quad dominant or toe runners, especially female athletes with wider hips and greater "Q" angles, are prime candidates for knee hip and ankle injuries. You will explode with force by extending the hips forward and up using the gluteus from a loaded position. This is the desirable source of power in the hit, as the goal is to transmit hip lift power up the kinetic chain from prime movers

3. Good explosive torso angles
Hip extension causes your legs to accelerate up in a unified explosive movement; however, if your body mass is located directly above your legs, your torso decelerates. The result is a vertical jump, not a forward movement. Forward acceleration as a result of hip extension happens when most of your mass is forward of your legs, therefore, every hit requires forward torso leans from the ankles, not the hips.

4. Pre-tense the core
Relaxation promotes emotional serenity; however, this concept is undermining of stroke production unless it is clearly understood, since good movements require mobility in some joints and stability in others.
Core tension is vital to stroke mechanics because as forces travel up, they pass through the core muscles on their way to the torso. A relaxed core is an unstable body part and an inefficient transmitter of power, because only neutral spine positions transmit force from the ground up. Relax your mind as well as those parts of your body that should be loose, like the hands and facial muscles, but tense and set your core before hinging your hips.

5. Strong shoulder positions
Throw a punch with your shoulders rolled forward and up and notice how your arms disengage from your body. Now take your shoulders and pack them back and down and punch again. This is powerful because back stabilizing muscles are activating to connect your arm to your body. The power generated by great hip extension and a rock-solid core isn't going to connect if force doesn't find its way from your torso to your arms.

6. Internal shoulder rotation
The result of good shoulder position is the ability to perform an internal shoulder rotation. This can be thought of as screwing your arm into your shoulder as a bulb is screwed into a socket. This corkscrewing of the arm is essential to the transmission of explosive power. Try throwing a punch with your thumb facing up during the entire movement. Now rotate your thumb in the direction of your opposing arm as you strike. You don't have to be a black belt in martial arts to recognize what all martial art masters know. These internal forearm rotations facilitate speed and transmit force. Trigger words and phrases that refer to spin such as “low to high," "brush the ball" and "10 o'clock to 2 o'clock" are misleading and insidiously counterproductive because they don't distinguish whether the vertical racket movement is produced by mechanically sound, and well-timed internal movement, or dangerous, inconsistent and uncoordinated external rotation. What about the ubiquitous wrist snap that I often hear students being told to perform? Try a few wrist snaps at the end of your punch and see if the result is greater power or a complete disconnect of force.

7. Arm to leg timing
You cannot run with coordination unless your arm and legs synchronize. It is interesting to note that the limiting foot speed movement factor in athletes who are not highly trained is arm speed and not leg speed. Quicken up the arm that opposes your foot with efficient movements and you will run faster. Similarly, cross arms and legs must coordinate as you perform a stroke or you will lose power, stability and linear momentum. As your legs move faster, your arms must keep pace. Since greater arm speed is elusive, most often, the best adaptive movement is to shorten and compact the stroke.

8. Accelerating arm positions
Effective ball striking like effective running reflects strong arm action with correct position and amplitude of arm and hand movement. Great runners start their arms at their pockets and powerfully exchange their hands up to their ears with an emphasis on the movement from the shoulders upward to encourage the transmission of force from the ground with balance and force. Sound strokes reflect these same strong upward arm to leg accelerating swings. Our brains are neurologically hardwired to encourage emulating symmetrical, arm and leg movements.

9. Balancing momentum and deceleration
Imagine that you are pedaling a bike. If you stop spinning the pedals, the bike will still coast from inertia. You must actively apply the brakes to stop immediately. Great stroke mechanics encourage the gentle and natural discharge of linear momentum without the destabilizing and lifting effects of abrupt deceleration. Balance while moving is the direct result of unchanged acceleration, or dynamic equilibrium, and nowhere is this movement flow more important than in those critical moments surrounding the hit. All movements have these three parts: A lift, acceleration and a landing. Balanced landings are vital to successfully stringing movements. Soft landings using good absorption angles of one step become powerful lifts with strong application angles in the next step.

10. Grips
Explosive force from the ground up must ultimately connect to the racket and the bridge to facilitate efficient transfer is the grip. Most grip dysfunction in good players result from an attempt to compensate for inadequate power transmission by griping the racket to maximize power from external rotation. If you correct only the grip, you will succeed in only removing the compensation, therefore, isolated grip corrections treat the symptoms of an underlying problem not the cause. First, effectively create power transfer to the racket with internal rotation and grip corrections will be minimally invasive and disruptive.

While the body knows movement, not muscle, reliance on science, not self-awareness is the foundation for progress. Power transmission from the ground to the racket is the result of a synergy of movements that must be examined from beginning to end to be clearly understood and effectively developed since body systems in stroke production and running form are kinesthetically interactive. Good strokes facilitate and mirror sound running technique, and correct running mechanics promote good strokes. Even the slightest lack of integrity in any link of either chain will cause correcting compensations, in both forms of movement.

Stroke mechanics will progress from good to great when movement acceleration transmission problems are identified and their causes are corrected.

Steven Kaplan

Steven Kaplan is the owner and managing director of Bethpage Park Tennis Center, as well as director emeritus of Lacoste Academy for New York City Parks Foundation and executive director and founder of Serve & Return Inc. Steve has coached more than 1,100 nationally-ranked junior players, 16 New York State high school champions, two NCAA Division 1 Singles Champions, and numerous highly-ranked touring professionals. Many of the students Steve has closely mentored have gone to achieve great success as prominent members of the New York financial community, and in other prestigious professions. In 2017, Steve was awarded the Hy Zausner Lifetime Achievement Award by the USTA. He may be reached by e-mail at StevenJKaplan@aol.com.