A tennis racket striking a ball sends vibrations down through the frame and all the way to the grip. Regardless of whether the racket is wood or graphite, cheap or expensive, vibrations reach the player on every shot. Some believe the use of vibrations dampeners -- devices applied directly to the racket strings -- has the effect of muffling vibrations and changing the feel of contact between racket and ball. Research on the subject, however, refutes that notion.
What Causes the Vibration?
According to Yohan Chang, frame vibrations in a tennis racket are derived from the change in kinetic energy after impact with the ball. A racket needs to have a certain amount of flexibility -- allowing for the bend in the frame and subsequent vibrations when hitting a shot -- because a racket that is overly stiff will end up passing all of the shock from impact onto the arm of the player. An overabundance of vibration has not been proved to cause tennis elbow or other related conditions, but the shock can irritate such existing injuries.
Types of Shock Absorbers
Tennis legend Rene Lacoste invented the first antivibration device in 1960 -- an indication that attempts to address racket vibration have been around for some time. Most modern dampeners are made of plastic and fit between the two central main strings -- the strings running from the top to the bottom of the racket. A less expensive, homemade approach to vibration dampening involves the use of a rubber band. Tied around the bottom of the central main strings, it has the same basic effect as the manufactured version. In fact, an endorsement of the rubber band dampening can be found in Andre Agassi's use of them for his rackets.
What the Science Says
When it comes to tennis racket shock absorbers, science has very definite answers as to the benefits. Quite simply, vibration dampeners do not work and serve no scientific purpose, according to research at the University of Birmingham in England. Results of that research showed that all the dampening devices do is alter the sound of the racket at impact. The reasoning behind this conclusion centers on the fact that the shock absorbing accessories are too small in relation to the racket to absorb any significant level of vibration.
More Effective Ways of Dampening
Just because the traditional antivibration devices don't have the intended effect does not mean that there are not ways in which to reduce the vibration in rackets. Yohan Chang writes about the potential use of a handle-end weight filled with sand. The added mass, Chang contends, would have the effect of dissipating a significant portion of the excess energy that travels down the frame. Additionally, Chang refers to the Pro Kennex Kinetic system -- present in the Pro Kennex brand of rackets -- which incorporates particulate masses in the head of the racket to create the same effect.
Psychological and Physical Effects
Despite the scientific evidence, top tennis players such as Rafael Nadal and Andy Roddick continue to use vibration dampeners. One possible explanation, according to Francois-Xavier Li, is the psychological effect. Lie suggests that players who believe that the devices work take comfort in having them on their rackets. The same is likely true for other players at all levels who use them. Tennis elbow and tendinitis -- which are sometimes thought to be held at bay by dampeners -- clearly do not benefit from the devices, though some players may believe they do.