Investigating the effect of ball impact location on the overhead motion in tennis during game play

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Ainhoa Iglesias Diaz (Creator)
Western Carolina University (WCU )
Web Site:
Martin Tanaka

Abstract: Tennis is a competitive sport played by millions of people worldwide. The characteristics of the game of tennis produce stress on the musculoskeletal system, especially in the upper extremity. Upper extremity injuries often occur when the arm is highly accelerated, as happens in tennis. These high accelerations require large forces to be applied to the wrist, elbow and shoulder. Upon ball impact, a large amount of force is transferred to the ball from the tennis racket. However, depend- ing on the impact location, large reaction forces can also be produced in the body. These large reaction forces must pass through the kinematic chain from the hand to the wrist, elbow and shoulder joints and into the torso. As a result, wrist, elbow and shoulder joint injuries are common. Motion capture has been used to study the biomechanics of the overhead motion in tennis; yet, this method measures pre- and post-impact dynamics not the actual instant at which the interaction between the ball and the racket occurs. Therefore, to make a more accurate representation, the impact itself needs to be studied. Investigating the impact itself will provide more insight into what is happening at the exact moment of the collision and how the kinematic chain is a ected. A commercial racket was purchased and customized by substituting the orig- inal handle by a one inch diameter acetyl rod, and adding unidirectional and triaxial strain gauges to it. A custom electrical circuit was designed and built to measure the strain in the racket handle during ball impact. Two participants used the instrumented racket to each hit a total of 20 regular serves divided into 4 di erent sets. Participants were photographed during the serve using a high speed camera at 120 frames per second. These photographs were used to identify the ball impact location of each serve. Strain waveforms collected using a custom electrical circuit were ana- lyzed to determine the peak ball impact force, the wrist reaction forces, and torques from the bending moments developed in the racket handle during impact. Results showed that the instrumented tennis racket was able to evaluate the e ect of ball impact location of the overhead motion in tennis during game play. The instrumented racket was able to measure ball forces, wrist reaction forces (equal in magnitude to ball forces but opposite in direction as a result of not taking into ac- count the transfer of linear and angular momentums) and torques generated by the bending moments at the hand during ball impact. This device or an improved version may be useful to get a better understanding of the forces and moments created with di erent types of movements during tennis play. It would be especially useful when employed in collaboration with a motion cap- ture system. A more complete understanding of tennis biomechanics can be gained by including racket impact forces and bending moments with motion capture to quantify the e ect that ball impact location has on the transfer of forces to the joints passing through the kinematic chain.

Additional Information

Language: English
Date: 2014
Tennis -- Physiological aspects -- Research -- Technological innovations
Impact -- Physiological effect -- Research -- Technological innovations

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