How to Choose the Best Tennis Racquet for Control and Power

Jo-Wilfried Tsonga
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When we read tennis racquet reviews or manufacturer descriptions, two words we're sure to see mentioned often are power and control. In the following, we'll look closely at what power and control mean, discuss the key technical specifications, and arrive at some recommendations about what to look for in seeking the ideal racquet.

Let's begin with some essential principles of racquet physics:

The long axis of a racquet is the imaginary line from the end of the handle to the tip of the frame.

If you put the tip of your racquet on the ground and give the racquet a spin, the long axis is the line around which the racquet rotates.

When the ball hits your strings above or below the long axis, your racquet's response depends mostly on how much weight is in the racquet head, how far from the long axis that weight is distributed (which partly depends on head width), and how flexible is the frame. On off-long-axis hits, with all other factors being equal, less weight (or less widely placed weight) in the racquet head allows more rotation around the racquet's long axis (torsion), because the racquet head has less mass on either side of the long axis to provide rotational inertia. Off-long-axis hits also put extra stress on the frame materials, and a more flexible frame twists out of shape more readily. Both reactions to the ball-racquet collision introduce unintended upward or downward tilt of the racquet face when the ball leaves the strings, with the turning due to lightness usually considerably greater than the twisting due to flexibility.

When the ball hits the racquet face off the long axis, the racquet loses some power, and the loss of power can either mitigate or exacerbate the effect of the tilted racquet face. If the ball hits above the long axis, causing an upward tilt, the loss of power will help to prevent your hitting long. If the ball hits below the long axis, causing a downward tilt, the loss of power will make it more likely that you'll hit the net.

The impact of the ball bends a more flexible frame backward farther as well, not just on off-long-axis hits, but on all hits, especially those closer to the tip. This introduces another variation in the angle of the racquet face when the ball leaves the strings, changing (slightly) the left-right direction of the ball instead of the up-down direction.

The above leads us to an important conclusion that's highly relevant to control: A stiffer racquet with more weight in its head is less likely to send the ball off at an unexpected angle.

Stiffness and weight, especially head weight, also have a major effect on power.

Most people understand power accurately as the amount of speed the racquet gives the ball on a given swing. A racquet's power is determined much more by its frame than by its strings. Within the normal stringing range, looser strings will usually make a ball go farther on groundstrokes, and this is often mistaken as an indication of greater power, but the ball goes farther not because it leaves the racquet at greater speed, but because it leaves the racquet later.

With looser strings, the ball stays on the racquet longer, and on most groundstrokes, the racquet face tilts upward more as you swing the racquet forward. By leaving the racquet later, the ball leaves on a higher trajectory, which makes it go farther.

The speed at which the ball leaves the strings is determined by how much of the energy in its collision with the strings is returned. With a stiffer frame, less of the energy in the ball-racquet collision gets absorbed in deforming the frame materials, so more of that energy goes into deforming the string bed and the ball itself. One might expect that when the frame springs back to its original shape, it will return much of the energy it had absorbed, but by the time the frame springs back, around 15-20 milliseconds after impact, the ball, which leaves the strings within 5 milliseconds, is already gone. The energy used to deform the frame is thus wasted, but not so the energy stored by stretching the string bed and compressing the ball.

The strings and the ball both rebound quickly enough to return much of their energy, so at a given impact speed between ball and frame, a stiffer racquet, which keeps more energy in the strings and the ball, returns more energy in the form of outgoing ball speed. In other words, a stiffer frame is more powerful.

At a given impact speed between ball and frame, a racquet with a higher swingweight is also more powerful. Swingweight generally increases with overall racquet weight and more of that weight placed in the racquet head. We won't elaborate on why greater swingweight increases power at a given swing speed, because it should make immediate sense from everyday experience: A heavier hammer drives a nail farther per strike. If you're familiar with momentum and kinetic energy, this should make even more sense, because both are directly proportional to mass.

So, we've reached essentially the same conclusion for gaining power as we had for reducing unexpected racquet twists and turns: Look for a stiffer racquet with more weight, especially in its head.

But, aren't power and control usually cast so that if you gain one, you lose some of the other? If all we wanted were maximal power and minimal twisting and turning, racquet selection would be a lot simpler than it is. Part of the problem is that there's a lot more to control than just the lack of twisting and turning.

Generally, more power is welcome -- as long as the ball goes in. To get our shots in, we depend on two distinct physical forces. Without them, the vast majority of tennis shots, which leave the racquet going slightly upward, would keep going slightly upward forever. The more essential force is gravity, without which you'd need a new can of balls every three shots, not to mention such nuisances as drifting off into space yourself!

The other essential force is air resistance, which becomes increasingly important as players use more spin. Topspin, in particular, helps to bring a more powerful shot down into the opponent's court by increasing the friction between the top of the ball and the air, in effect, making the air push downward upon the ball.

If we ignore the effects of spin (and human psychology) for the moment, and consider only the relationship between power, racquet angle, and gravity, finding the racquet that offers maximum control will be a direct function of two fairly intuitive definitions of control. If we define control simply as predictability, a stiffer and heavier (or more head-heavy) frame clearly offers more control, because of its resistance to the turning, twisting, and bending backward that create unpredictable racquet angles. The other common understanding of control is to limit power so that one doesn't overhit.

In the simplified (no-spin, no psychology) world we've constructed, the logical conclusion from these two definitions of control should be obvious: Use a heavier, stiffer racquet and don't swing so hard. Physically, a shorter, slower swing is, in itself, easier for you to control, so if you can get just as much power with better control using such a swing with a heavier, stiffer racquet, why would you do otherwise?

One reason you might not choose to take a shorter, slower swing comes from your head. It's more fun to take a big, fast swing, and a major part of why it's more fun is crucial to the question of control. When you take a big, fast swing, you abandon caution. Caution has its virtues, but fun isn't one of them, and in tight match situations, too much caution can be your worst enemy. If you have to carefully measure how much speed to put into each of your swings, you will tend to be much more anxious at crucial moments in competition than if you can just let loose on your shots without thinking about it. If your control depends on applying just the right amount of swing speed, which in turn depends greatly on your brain, your shots will suffer most when your brain is most under stress, such as on the most important points in a match.

Another reason you might want a longer, faster swing involves spin, which we've deliberately overlooked until now. Along a swing path that cuts upward at a given angle to create topspin, the faster you swing, the more spin you'll generate. With more topspin, you can keep harder and higher shots within the court, so topspin creates a marriage between high swing speed and high control -- assuming that you can meet the ball cleanly.

The swing path you use to create more topspin is one that cuts upward more sharply, which reduces the period of time during which the racquet path and ball path are aligned. Your timing must be considerably more advanced to meet the ball cleanly with a sharp upward cut than it need be to meet the ball with a more forward swing. Swinging more forward just as hard is easier in terms of timing, but much more demanding of a different kind of skill, the ability to hit through a fairly low margin above the net. If you've advanced to the point where you can use topspin to maintain control with a fast, powerful swing, or you can accurately hit hard through a narrow slot above the net, you have what every tennis player wants -- except perhaps the ideal racquet.

A player who wants to use long, fast swings needs a racquet that offers the following characteristics:

Predictability:
Hard, flat hitters need predictability because unexpected racquet angles are the last thing you want when you're trying to hit through a narrow margin above the net.

A racquet that twists and turns is just as problematic, if not more so, for a player who hits heavy topspin, because if you're swinging upward to create spin and the racquet turns or twists upward, the upward tilt not only sends the ball on a higher trajectory, but it also reduces the brushing action through which the strings give the ball topspin.

With more lift and less topspin, your ball will go a lot farther than you intended. Furthermore, if you're trying to hit topspin, you can't avoid unexpected tilts by perfecting your skill at meeting the ball exactly on the long axis. Topspin strokes generally require the ball to impact the string bed above the long axis, roll downward across the long axis, and leave from a point below the long axis. For topspin players, variations in up-down racquet tilt have a major effect on depth of shot, and a lot of topspin players address this problem by leaving a huge margin for error. They end up hitting at an average depth closer to the service line than the baseline, but they would be much more formidable if they could safely aim deeper.

In terms of the racquet frame itself, stiffness enhances predictability. So does greater string tension, because the ball leaves tighter strings sooner, thus giving you less time to accidentally change the angle of the stringbed while the ball's still there.

If you string too tightly on a stiff frame, though, your arm will feel the effects of the condensed duration of the ball-impact shock. This imposes an important limit on how far you can go in seeking predictability.

A limited power ratio:
Each player has a limit on the degree of upward cut (to create topspin) that's feasible per average swing, so if your racquet has too much power for the amount of spin you can generate with a full-speed swing, you'll hit long.

The more recent laboratory studies indicate that there's not a great deal of difference between racquets and strings in terms of how much spin the ball receives, given the same swing path and speed. Tighter strings, rougher string textures, and wider string spacing help, but not by a factor of more than 10%, and racquet frames themselves determine spin even less. The key, therefore, to finding the right power-to-spin ratio is the racquet's power, not its spin potential.

For the flat hitter, the analogue to the power-to-spin ratio is the power-to-accuracy ratio. At a given swing speed, a more powerful racquet will require a flat hitter to aim through a smaller margin above the net. If you gain at least as much predictability as power, though, aiming though a smaller margin won't be more difficult, because a more predictable racquet gives you better control over the height of your shot.

Mass you can maneuver:
Given all we've said about the disadvantages of lighter racquets, we should note their virtue: They're easier to swing fast and to get in position for quick reactions. You don't want a racquet that's so heavy, you feel encumbered by its weight, but for adult players of average strength, such overweight racquets are quite rare in the current market.

Arm safety:
Racquet weight and stiffness can make a huge difference to the health of your arm. When a light racquet head turns in response to an off-long-axis ball impact, the turning force (torsion) is transmitted through the racquet handle to your arm. A light racquet also absorbs less of the basic shock of the ball's impact, whether you hit on the long axis or not. Torsion and shock both commonly lead to tennis elbow and other injuries. In one sense, a more flexible frame mitigates these problems by spreading the torsion or shock over a greater period of time and thus reducing the peak strain on the arm, but a more flexible frame also vibrates back and forth more violently after impact. Although no one can see this "flutter" with the naked eye, many players who aren't used to flexible frames can feel it quite distinctly.

Flutter has not been proven to cause injury, but to players who notice it, the discomfort it causes to the arm is much more concerning than the purely aesthetic annoyance that string vibration causes to the ears.

So, what's the ideal racquet?

For a player who uses relatively short, slow swings, few, if any, racquets currently on the market would be too stiff. Weight and balance become issues once you find the racquet hard to maneuver, but most of the racquets on the current market are unlikely to be too heavy (or head-heavy) for an adult of average strength. Most players who use relatively short swings can easily maneuver a racquet that weighs around 11 ounces (strung) with a balance within 1/2 inch of even, and a stiff racquet so weighted and balanced should be an excellent choice.

You can also look for a swingweight between 320 and 340, but don't rely on that as your primary indicator.

What's the best racquet for a player who wants to use longer, faster swings?

Weight and balance:
Most adults with normal strength have no trouble wielding a racquet with a strung weight of 11 ounces and a balance not more than 1/2 inch head-heavy. Racquets of at least 11 ounces tend to be head-light, not head-heavy, to make them more maneuverable, but too little weight in the head introduces all of the problems discussed earlier. For each 1/10 ounce above 11 ounces, something on the order of 1/8 inch (one point) more head-lightness should generally be acceptable, although a more even balance would be preferable for many stronger players. A strong player might comfortably use an evenly balanced racquet weighing more than 12 ounces strung, and many of the pros customize their racquets with extra head weights that bring the total well above 12 ounces.

Look for a swingweight of at least 320, but pay more attention to weight and balance.

Stiffness:
As noted earlier, the main limitation on how stiff a racquet you can use with good control is your ability to generate enough spin (or to hit through a smaller margin above the net) to keep the racquet's power from sending the ball too far when you swing as fast as you generally like to swing.

Most of the racquets currently sold for advanced players are more flexible (and more head-light) than would be ideal for an advanced playing population who were coming to the market without having already been conditioned to the racquets they've been offered over the years. Players tend to like what they're used to, and most advanced players have gotten used to the more flexible frames that have dominated what manufacturers have marketed to them since the days of wood (which was extremely flexible). Whether a stiffer racquet feels better or worse for your arm depends largely on whether you're bothered by the flutter of a more flexible frame. In terms of predictability, though, most advanced players would benefit from a stiffer, more evenly balanced, and in many cases, heavier racquet. With a racquet weighing around 11.5 ounces, a balance within 6 points (preferably fewer) of even, and a stiffness of 70-75, most advanced players can swing just as freely as ever, and the racquet's somewhat greater power is offset by the more consistent angle at which it sends the ball on its way.