Biomechanical analysis of top tennis players
Gideon Ariel, Ph.D.1, Vic Braden1, Ann Penny1, John Probe1, Rudolf Buijs1
and Alfred Finch2
1 Institute for Biomechanical Research, Coto Research Center, Coto De Caza California,
2 Indiana State University, Terre Haute, Indiana, USA
The purpose of this paper was to perform kinematic analyses of some of the top
players in the World during a major competition using multiple view video images
that were transmitted and digitized over the Internet. Backhand and serve stroke
data for Federer, Clijsters, and Agassi were selected for the present study.
Keywords: elite tennis players, tennis biomechanical analysis, Internet analysis
Considered to be one of the great major events including the Grand
Slam tournaments, the Pacific Life Open has evolved into one of the elite international
sporting events in the world today. The Pacific Life Open, March 7th to March
20th 2005, hosted the most recent International Tennis Tournament with the top players
in the world competing.
This study evaluated the kinematics of elite tennis players stroke mechanics during
a major competition using video images that were collected, transmitted, and analyzed
over the Internet. Because of the limited space, only the backhand and serve stroke
data for Federer, Clijsters and Agassi are presented in this paper.
The APAS System was utilized to collect video data from 3 stationary
cameras on the field at 60 Hz. Video was transmitted automatically through Internet
connection. The digitized joint centers were: feet, ankles, knees, hips, shoulders, elbows,
wrists, hands, head, 6 points on the racket, and the ball.
Direct linear transformation and digital filtering at 10 Hz were utilized to calculate
the 3D coordinates of each joint. Joints and segmental displacement, velocities
and accelerations were then calculated. The main parameters to be analyzed for the
present study were determined by one of the leading tennis professionals and coach,
Vic Braden. These parameters were: velocities curves for the racket and the
ball angular velocity for the racket and forearm. The translation phase represented
the horizontal displacement of the racket from initial ball contact to ball separation.
A summary of the linear velocity alterations during the
racket interaction are
presented in Table 1. During the backhand ground stroke, the hand velocity during
the time interval prior to contact to after ball impact increased 25%, 0%, and 7%
for Agassi, Clijsters, and Federer, respectively. During the same time period, the
racket head tip velocity decreased 72%, 13%, 27% for the same tennis players. This
would indicate that the players were either recoiling or decelerating the racket
head after ball impact. As the ball interacted with the strings during the ball
contact, the elastic energy that was returned to the ball resulted in ball velocity
increases of 189%, 245%, and 204% for the same players. Similar increasing percentages
were observed for other strokes analyzed.
Table 1 - Linear velocities of the hand, tip of the racket and ball velocities
prior to and after impact with the ball (km/h) and the peak racket angular velocity
The video images of elite tennis players during the Pacific Life
Open tennis tournament were transmitted via the Internet, digitized, and analyzed
off-site, and then selected kinematic data were shared with the athletesï¿½ coaches
at the competition. Recently developed innovations in video collection, Internet
transmission and analysis have provided viable means for conducting biomechanical
analyses for athletic performances held at sites throughout the world. Results from
such biomechanical analyses of top tennis players in a recent International tournament
revealed kinematic data of the bodyï¿½s segments, racket and the ball velocities that
could be used in coaching applications.