The following is a page from The Fault Tolerant Forehand, available in eBook and paperback formats on Amazon (click here).
Every player has been coached to “brush up the back of the ball” in order to generate topspin. While this advice is technically correct, it’s very misleading as to how this famous “brushing” actually happens. Most players understand that they need to swing up and through the ball, but what many haven’t been taught is that it’s also essential to swing out to the ball. There are three critical vectors to the correct swing path, not two.
Out, up, and through.
Of these three directions, the out part is the most overlooked. Despite it’s lack of popularity though, it is essential to generating a heavy, fast forehand, and it’s actually far more important than the up direction. Only a swing containing the out vector imparts forces on the racket that cause it to naturally rotate around the wrist through the hitting zone.
This racket rotation is the less understood, but more important of the two fundamental movement patterns that are used to generate topspin in tennis.
The Two Topspin Movement Patterns
The two movement patterns that generate topspin in tennis are very different in their execution. The first – the well known one – is upward translation of the racket-arm system through contact. As the player hits, if the racket-arm system is moving up, then, at impact, friction with the back of the ball will generate torque on it and create topspin ball rotation. This is the “swing low to high” idea which we’ve all heard countless times.
However, the other movement pattern that generates topspin is far more important, especially at the highest level – racket rotation about the forearm. Through the hitting zone, the racket whips around the wrist, about the axis of the forearm. This rotational whip constitutes the traditionally named “windshield wiper” motion, and it also creates an upward frictional force on the back of the ball at contact.
Whether or not the entire arm-racket system is translating up, when the racket is rotating about the forearm during contact, the racket itself is still explosively moving upward through the strike (even if the arm is not). And this upward racket motion, the motion generated by racket rotation, is responsible for a lot more of the total upward frictional force imparted at contact than any upward translational motion is.
Topspin on the Tour – Primarily Racket Rotation
You’ll often see tour level players hit heavy topspin shots while barely even using an upward translational component in their swing – their follow-through ends up below their non-hitting shoulder. How is that possible? Heavy topspin without the racket-arm system moving drastically up through contact? How did they generate all that spin without swinging “low to high?” It works because they’ve generated almost 100% of their spin using the racket rotation contributor, rather than by translating the racket up.
Additionally, the heaviest spin players, players like Dominic Thiem and Rafael Nadal, will often use both movement patterns together – they both swing the entire racket-arm system up, and they relax, swing out, and allow the racket to whip about their forearm. The result is that they finish these shots above their head, and by utilizing both topspin generating techniques together, they generate some of the highest RPM forehands on the tour.
Elite players also utilize the same biomechanics on every forehand, regardless of contact point. Racket rotation can be easy to lose, especially on low balls, if adjustment to low contact is performed incorrectly. Instead of adjusting their contact height using their arm – pulling it closer to their body to get the racket lower – elite players adjust by sitting down lower and tilting their torso. This way, the arm can flick out and around the body in the same motion relative to the trunk at every contact height, even a low contact. And thus, elite players do not lose the anatomical advantage of racket rotation when contact needs to me made lower than usual.
The Role of the Out Vector
So what does out have to do with any of this?
The out vector is the result of the volitional action by which we generate this racket rotation, the most important contributor to topspin. By consciously swinging out to the ball and contacting it laterally away from the body, we generate the force that causes the racket to naturally whip around the wrist.
As we begin our hip rotation and swing the racket out to the ball, the racket naturally lags behind our relaxed wrist. Then, as the racket gets to the end of its outward trajectory, the hand naturally pulls on it, causing it to whip around.
It’s like the racket is connected to the end of a string, and when the string goes taught, when our arm is finished extending, then the racket’s path continues around whatever trajectory it was started on before it hit the end of that range of motion – in this case, that inertia causes the racket to rotate about the athlete’s forearm.
This is not the case if the racket is flung to a contact point that is laterally closer to the body; in that case, there’s no outward force on the racket during the swing, and so the resulting racket motion as the racket hits the end of its range of motion is just back-to-front, no rotation. This pure, translational, back-to-front swing was common in the past in tennis, but it’s a swing that can’t generate anywhere near the level of racket head speed and topspin that the modern swing can.
Conscious Effort vs Automatic Results
As tennis instructors, it’s important that we make it abundantly clear which movements during a swing are volitional, and which ones are automatic. Racket rotation about the forearm through the hitting zone is automatic – it is NOT created via conscious effort, and the wrist and hand musculature do not play ANY role in generating this rotational force (though they do stabilize the racket and string angle while that rotation is happening).
This is an extremely common misconception – many coaches harmfully instruct their students to “use your wrist,” despite the fact that the wrist’s job is just to relax and to allow forces generated by other parts of the body to act on the racket and whip it around that relaxed wrist. Wrist lag, racket rotation, and essentially the racket’s entire swing path after the volitional initiation of the forward swing constitute dynamic positions; they are entered automatically as a result of other intentional actions taken before them.
Confusion Surrounding “Wrist Action”
When tennis commentators talk about “great wrist action,” what they really mean is that the player does a great job of relaxing their wrist and allowing their wrist to act as a hinge transferring force into the ball, not that the wrist is in any way generating the force itself.
And when they talk about a player having a “strong wrist,” that’s simply a reference to the fact that the harder a player swings, the stronger their wrist must be to stabilize the racket during that swing. It is NOT implying that the player’s “strong wrist” is creating that racket head speed by using its strength.
The action that actually generates the racket head speed is the trunk rotation which flings the racket out and through the ball. Therefore, the action that a tennis player should think about while playing is just that – swing out to the ball and strike it away from the body.
Do that with a relaxed wrist, and as your racket gets to the end of it’s range of motion, it will naturally and automatically rotate. Any conscious attempt at using the wrist or the arm to create the windshield wiper motion will typically just lead to harmful wrist tension, ineffective shots, and injury.
So How Do I Actually Apply This?
The physics at play during the windshield wiper motion are pretty complex, so ignore the physics themselves when you’re on the court (but understand them off the court). Instead, just remember the cause and effect:
Cause – swinging out to the ball with a relaxed wrist
Effect – the racket will whip around the wrist and rotate through the contact zone
We use this knowledge to debug our own forehand. If you feel like, one day, you aren’t getting sufficient topspin on your shot, a failure to properly swing out to the ball may be the culprit.
We’ve all had the experience where, certain days, our stroke feels great, but then, other days, all of its fault tolerance has evaporated and it’s a struggle to even get it in the court. Perhaps you’ve accidentally started violating the fundamental theorem of tennis. Perhaps you’re fatigued (or just being lazy), and you aren’t playing low and wide enough. Or perhaps you’ve subconsciously altered your contact point, pulling it in towards the body, thereby preventing that dynamic, rotational racket flick which generates so much spin.
Remembering to swing out, up, and through the ball, instead of just up and through it, is one more tool in your toolbox for fighting that inconsistency, and consistently maintaining that heavy, fast, fault tolerant forehand that makes tennis so fun to play.