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Old 03-10-2007, 08:23 PM   #22
D-man
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Join Date: Sep 2004
Posts: 752
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Quote:
Originally Posted by 10ispro View Post
http://www.stms.nl/december2005/default.html

From the literature
String Vibration Dampers Do Not Reduce Racket Frame Vibration Transfer to the Forearm
Li FX, Fewtrell D, Jenkins M.
J Sports Sci. 2004;22(11-12):1041-52.


In this study, the effect of string vibration damping devices on reducing racket frame vibration transfer to the forearm were examined. Twenty participants volunteered to hold a tennis racket stationary in a forehand and backhand stroking position while tennis balls were fired at 20 mĚs-1 towards two impact locations, the node of vibration and the dead spot. A three-way analysis of variance with repeated measures on damping condition, impact location and stroke condition was performed on the data. The resonant frequency of the hand-held racket was found to be approximately 120 Hz. No significant differences in amplitude of vibration at the resonant frequency were found for the wrist or the elbow when damped and non-damped impacts were compared. Impacts at the dead spot produced greater amplitudes of vibration (P < 0.01) but no interaction between impact location and string dampers was evident. The string dampers had no effect on the grip force used or the muscle electrical activity in the forearm after impact. In conclusion, we found that string dampers do not reduce the amount of racket frame vibration received at the forearm. We suggest that string dampers remain a popular accessory among tennis players because of their acoustic effects and psychological support rather than any mechanical advantage.
I know some people will not be convinced no matter what I say, but this study is, in my opinion, far from conclusive, or even really scientific, and is quite arrogant and condescending in its authoritative tone. So some 20 players held a racket with a ball hitting the strings. First, I don't think that accurately reproduces the dynamics of a full swing, especially on a mis-hit. What level were the players, and how good was their form? With good form less vibration is transferred. What rackets did the players use? What dampeners were used? I've tried many dampener styles, and they all feel very different to me. What strings were used? Some strings transmit more vibration to the frame.

For me, of course, my own experience is more powerful since I am not the kind of person to deceive myself. I do have a rather scientific mind and I never be dishonest about what I feel. Dampeners make a signficant difference for me in the whole feel of a stroke, not just the sound. Also, I have experienced with them in all different ways for many years. I suffer from various arm aches due to my poor technique, and they have definitely helped me. In one experiment I tried, my whole arm vibrated and ached without the dampening device, but with it all was well. Scientific studies be damned, I know I am not making it up or having a placebo effect.

So all in all, the most naysayers seem to be people that have no arm troubles anyway, and have never even extensively tested this. I wonder why they want to be so vociferous? But for those who are interested I think there is enough personal testimony to give it a try. Rubberbands work good. I actually most often use two fat rubberbands and a circular dampener in-between.
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