Interaction between tennis string type and tension and the subsequent effect upon ball rebound velocity

The present study sought to determine the interaction between tennis racket string type and string tension on ball rebound velocity. Five Slazenger tennis rackets, classified as "stiff" by their manufactures were strung at five selected string tensions; 200N, 222N, 245N, 267N and 289N (451bs, 501bs, 551bs, 601bs and 651bs respectively), with products of Ashaway Strings, USA NAMELY; Dynamite II, Tri-Cor 710 and Synthetic Gut "16". For each tension and string condition, five ball/racket impacts were filmed, at 100 frames per second (fps), using cinematography. Ball displacement was digitized utilizing an NAC motion analyser. Raw data was smoothed and ball velocities were subsequently calculated. Statistical analysis of the data found significant differences between string performances at certain tensions. A zero order Pearson product moment correlation matrix was compiled to identify any statistical relationships between the string types at particular tensions. Tri-Cor 710, strung at 200N (451bs) was deemed the criterion to which all other variables were compared. Results of this study proved significantly that Tri-Cor 710 outformed Dynamite II and Synthetic Gut 16, but generally, each string produced greater rebound velocities at the lower tensions. In addition, coefficient of restitution values were calculated which exceeded those determined in previous literature.