ENERGY EFFICIENCY OF DIFFERENT TENNIS RACKET STIFFNESS AND STRING TENSION DUE TO CENTER AND OFF-CENTER IMPACT

Abstract

The purpose of this study was to investigate the power of vibration responses and moments of different racket flexibilities and string tensions following center and off-center impacts. Three rackets, classed as stiff, medium, and flexible by their manufacturers, were strung at three string tensions and subjected to 15 trials. The rackets were gripped on a KISTLER force plate and impacted at designated areas by a rigid ball. The stiff racket had smaller powers of vibration and twisting moment for each string tension in offcenter impact. The largest power of vibration and twisting moment occurred respectively in the flexible racket strung with 50pound and medium racket strung with 70 pound in offcenter impact.