The sport of tennis has been played for centuries. Over hundreds of years, the technology of the game has changed dramatically. In the fourteenth century, a tennis racquet was more like a present-day squash racquet, having a long handle and small hitting surface shaped like a teardrop. Furthermore, with strings made of animal gut, the racquets' construction was quite different from their modern-day counterparts.
By the end of the nineteenth century, the shape of the tennis racquet head was more similar to the present-day design, although the head was flatter at the top rather than being rounded. Also, the size of the head was smaller than the present-day racquet head.
This design did not change appreciably until almost a century later, during the 1960s. Structural innovations that were introduced prior to the 1960s included laminated construction (where thin layers of wood are glued together, instead a using a single piece of wood to form the racquet) and the use of fabric strings instead of sections of gut.
A metal racquet existed prior to the twentieth century, but it was considered a novelty and was not well-received. In 1967, the Wilson sporting goods company introduced a steel racquet that proved to be popular. The racquet was lighter and less cumbersome than the existing wood racquets. Use of the racquet by Jimmy Connors—then a top-flight professional—brought the metal tennis racquet into the mainstream.
In 1976, Howard Head designed a racquet whose hitting surface was over 50% larger than the existing racquets. The use of aluminum as the frame material allowed the increased hitting surface to be incorporated into a racquet that was as light as the existing versions. The Prince Classic and Prince Pro racquets immediately became popular among recreational players, who found the greater hitting surface made it easier to make contact with the ball.
However, elite players found that the larger surface area could make the ball more difficult to control, as the racquet head would pivot slightly during the hitting stroke and at the point of impact. In contrast to strings, which rebound to their original configuration very quickly after contact with the tennis ball, the aluminum racquets required several milliseconds to resume their original shape. This reduced the energy that is transferred to the ball, and affected the accuracy of the shot.
To remedy this, a racquet material that was light but more resistant to torque, and was more efficient as energy transfer was needed. The answer proved to be a combination of carbon fibers and plastic resin that was dubbed graphite. One of the well-known tennis players who helped popularize the composite racquet was the late Arthur Ashe.
Tennis racquets are now constructed either of graphite or aluminum. Wooden racquets are a rarity.
Beginning in the 1980s, racquets with thicker frames were marketed. Designed to lessen the vibration felt when hitting a tennis ball, "wide-body" racquets did not achieve great popularity as they felt very stiff. However, some present-day players still prefer the increased power that these racquets produce.
During the 1990s, a tennis racquet was introduced that, at 28 in (71 cm) in length, was 1 in (2.5 cm) longer than the conventional racquet. The extra length enabled a shorter player to stretch slightly higher at the moment of impact with the tennis ball during the serve, producing a harder shot. Now-retired tennis professional Michael Chang used the longer racquet with great success.
Another aspect of tennis racquet construction that has changed over time is the grip—the portion of the racquet that a person holds to make a shot. The grip was originally made of wound leather. However, this material would become slippery when covered with sweat and would become brittle with age. Modern-day grips are synthetic, which provide moisture absorption and cushioning.
Strings have also evolved. Modern-day strings are also synthetic. Nylon is a popular material. Some strings are made of synthetic threads of material that are spun together to produce a string that is very strong yet flexible. These strings are very elastic; they deform when contacting a ball but quickly resume their normal length. This transfers a great deal of energy to the tennis ball very quickly, causing the ball to rocket off the racquet face. The tendency of the strings to deform is beneficial to the recreational player, since even an off-center shot will still tend to rebound back in the intended direction. Elite players will stretch the strings tauter and under greater pressure, to produce a harder return. This reduces the deformation of the strings, increasing the need for a player to precisely and accurately strike the ball.
Some strings are not of uniform diameter along their length. Instead, strings that run parallel to the racquet handle can increase in diameter from the bottom of the racquet to the racquet central region and then taper in diameter towards the top (or toe) of the racquet face. This acts to direct the most efficient hitting zone (the "sweet spot") more to the toe, which is the region where most recreational players tend to make contact with the tennis ball. By altering the string design, tennis racquet manufacturers can produce a racquet that is easier and more pleasurable for a recreational player to use.