Everyone's Racquet: Tennis Supplies and Service

Initial, high-amplitude oscillation (jarring) of the racquet during or immediately after ball contact. Often confused with frame vibration, frame shock is generally believed to contribute more to wrist, elbow and/or shoulder injuries than vibration. Generally, a smaller, stiffer, lighter racquet strung at high tension will produce more shock than a larger, flexible, lightweight frame strung loosely. Off-center hits also increase the amount of shock transmitted to the hand and arm. In fact, if you can hit the Center of Percussion (COP) area of the sweetspot each time, your shots will be shock-free. Certain handle systems (Dunlop ISIS & ShokBlok, Prince Cushion Grip) are effective in reducing shock before it reaches the hand. Additionally, Prince's Double Bridge and Pro Kennex's Kinetic System Technology are designed to absorb frame shock. After-market methods of reducing frame shock include adding weight to the frame, lowering string tension, using a thinner gauge string and increasing grip size (to a point) to reduce torque. String vibration dampers are ineffective at reducing or absorbing frame shock.

Simply put, the area of a strung racquet that provides the greatest energy return (power) and accuracy with the least amount of shock or vibration. There are actually 3 sweetspots: Sweetspot 1 is the Center of Percussion (COP) and offers the least amount of initial shock to the hand when struck. Shock is generally accepted as being potentially most harmful to player's arms. Sweetspot 2 is the Nodal Point (or Node) and produces the least amount of vibration when struck. Frame vibration is what players feel after ball contact (lingering, low-level oscillation) in certain (generally more flexible) racquets. While uncomfortable, frame vibration doesn't pose the same injury risk that frame shock does and can be effectively reduced with handle systems, such as Dunlop's ISIS and Prince's Cushion Grip. Sweetspot 3 is the area of Maximum Coefficient of Restitution, or a racquet's power. It is the lowest of the 3 sweetspots. Location of sweetspot is determined by several factors, including racquet weight, balance, length, headsize and string tension.

Measure of how heavy a racquet feels when swung, i.e. maneuverability. Also known as Moment of Inertia or Second Moment, swingweight is dependent on several factors, including racquet weight, length, balance, head size. A heavy swingweight racquet is more powerful than a light swingweight racquet (ATBE), but will be less maneuverable. Also, a heavy swingweight racquet can be relatively light in overall weight by placing the majority of weight in the head. A trend initiated by Wilson with their Hammer and Sledge Hammer racquets, the objective is to retain maneuverability without sacrificing power by distributing most of the overall weight to the upper hoop, where ball contact is made. Swingweight can be increased by adding weight above the pivot point (where the racquet is gripped) or by increasing length. Swingweight (like overall weight) cannot be reduced unless the bumper is removed or racquet length is reduced. Keep this in mind when selecting a racquet to purchase - better to err on the light side and add weight if needed.