(The information in this article was taken or adapted from the High Performance Coaching Program Study Guide.)
The rackets players select will strongly affect their tennis play. Biomechanics research is uniquely qualified to provide information for racket selection, as the mechanical behavior of both the racket and the player’s body must be understood to make good choices. Unfortunately, the aggressive marketing of tennis equipment focuses players’ attention on “innovative” and “high-technology” design features that may not improve play or lower the risk of injury. You can help reduce some of this misinformation, but much is still not known about how racket design elements interact with the player in affecting performance or risk of injury.
Many features of tennis rackets dramatically affect performance. Some key design features that have been researched and have stood the test of time are the variations in head size, frame width, and racket mass and distribution of mass. Grip size and other design factors also should be considered. Probably the most influential racket variable is the size of the head.
- Head size. Larger head sizes (oversized versus midsized) create higher speeds of ball rebound and have a larger sweet spot. (The term sweet spot here is used to mean the area on the racket face where the ball rebound is the fastest and most accurate. Other points on the racket face minimize the shock or vibration that is transmitted to the hand.) A large racket head also dramatically increases the racket’s resistance to twisting in off-center impacts.
- Frame width. Another key design variation is the width of the racket frame. Increases in the width of the frame increase its stiffness and eventually the speed of ball rebound (since not as much energy is spent bending the racket). The cost of such increases is the transmission of a greater impact shock to the arm.
- Frame mass. Modern tennis rackets have been getting lighter and lighter. However, greater racket mass is directly proportional to greater speed on a ball, if all other variables remain equal. The other advantage of a racket with more mass is that this mass helps protect the player’s arm by being more resistant to the acceleration of impact.
Example—Very light rackets are great for the fast movements of a serve-and-volley player, but provide less protection to the arm during the shock of impact. You might suggest to a player that he or she increase racket mass to help protect the arm or to mechanically discourage a tendency to swing wildly (over hit) at shots.
- Distribution of racket mass. The resistance to rotation of the tennis racket (swing weight) depends on where you grip the racket and the distribution of racket mass, more than just the mass itself. A racket can be relatively light, yet be head heavy and feel harder to swing. This concept must be viewed from two perspectives: first, as stated above, a racket with more mass near the end will be harder to swing (this is why children hold the racket up the handle to decrease the distance of the mass of the racket-head from the hand) and second, rackets with larger head sizes have the mass distributed further from the central axis of the racket (polar moment). This aids in stabilizing the racket in off-center impacts.
- Grip size. Help players select the correct grip size. A grip that is too small will be maneuverable, but will cause the muscles of the forearm and hand to work very hard to grip the racket. Larger grips are easier on the gripping muscles, but the hand/wrist will be less mobile.
Example—Players with tennis elbow problems might switch to a larger grip to decrease demands on the muscles and increase leverage to resist off-center impacts.
Other design variations. Many other variations exist in tennis rackets, from differences in length, the materials and composites of materials used, grommets, and overall design. Less is known about how all these factors interact when players actually use them. A longer racket, for example, should allow for a greater ball speed, but if the swing weight of the frame is increased, the benefits of length may be canceled out by a slower swing.
Rather than exaggerate the potential importance of the market claims of manufacturers, focus on the general tradeoffs already presented. Most of today’s rackets are much better than those of the past, so the best racket for a recreational player may be the racket that gets the player out on the court. Advanced players will have definite preferences for rackets and stringing, which you should examine for their suitability to the players’ styles of play.
Finally it should be stated that the key mechanical variable in ball speed is the speed of the racket not its structure. It is therefore critical that good technique be the primary aim of all coaches.