title: Lower-limb coordination and shoulder joint mechanics in the tennis serve.
abstract: OBJECTIVE
  To examine the relationship between variable lower-limb coordination and shoulder joint kinetics and kinematics in the high-performance flat first serve in tennis.
  
  
  METHODS
  Three-dimensional data describing three flat serve (FS) techniques, each executed with varying lower-limb involvement: foot-up (FU), foot-back (FB), and minimal leg drive (ARM), as performed by 12 high-performance male players were recorded using a 12-camera Vicon MX motion analysis system operating at 250 Hz. A discriminant analysis determined the lower-limb kinematics that distinguished serve technique, and by extension, leg drive. A total of 18 one-way ANOVA ascertained statistically significant differences in the kinematic and kinetic variables considered to relate to or represent shoulder joint loading in FU, FB, and ARM serves.
  
  
  RESULTS
  The lower-limb kinematics shown to best discriminate between service techniques were range of rear and front knee joint extension, and peak angular velocity of rear knee joint extension. The forward swings of the FU (43.6 +/- 3.0 m.s(-1), P < 0.05) and FB (42.6 +/- 3.1 m.s(-1), P < 0.05) techniques were characterized by higher peak racket speeds than those generated in the ARM (39.4 +/- 3.4 m.s(-1)) serve. Regardless of stance and leg drive, similar pre- and post-impact shoulder joint kinetics were developed.
  
  
  CONCLUSIONS
  Knowledge of a server's range of front and rear knee joint extension as well as his/her peak angular velocity of rear knee joint extension is sufficient to ascertain the stance and quality of leg drive used. When facilitated by a leg drive, high-performance players generate similar resultant pre-impact racket velocities independent of stance. With no leg drive, players develop lower resultant racket velocities. Comparable shoulder joint kinetics, however, evolved from the differential lower-limb mechanics that characterized the FU, FB, and ARM techniques.
authors.affiliation: School of Sport Science, Exercise and Health, The University of Western Australia, 35 Stirling Highway, Crawley, Australia. mmreid@cyllene.uwa.edu.au
authors.forename: Machar
authors.initials: M
authors.lastname: Reid
authors.forename: Bruce
authors.initials: B
authors.lastname: Elliott
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Alderson
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D016002:Discriminant Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*; D013715:Tennis / Q000502:physiology*; D014904:Western Australia