Comparison of Ball-and-Racquet Impact Force Between Two Tennis Backhand Stroke Techniques

William E. Prentice, Shyi-Kuen Wu, Bing Yu, Michael T. Gross

Study Design: A mixed design for kinetic comparison of 2 types of one-handed backhand strokes and 2 skill levels in tennis. Objectives: To develop and evaluate a model to estimate the impact force on the racquet during tennis stroke, and to compare the peak impact force between one-handed backhand stroke with a long backswing and one-handed backhand stroke with a short backswing and between the beginning and advanced players. Background: A one-handed backhand stroke is commonly used in tennis and may be associated with many upper extremity over-use injuries. An understanding of kinetics of the backhand stroke is essential for understanding injury mechanisms and prevention. Methods and Measures: Five male advanced tennis players and 4 male and 1 female beginning tennis players participated. Mean age was 32.2 ± 7.0 years. Each subject was instructed to use the 2 types of one-handed backhand strokes to hit balls from a tennis ball machine. Three-dimensional coordinates of critical body and racquet landmarks were obtained. A mathematical model was developed to estimate the contact duration and the peak impact force during a stroke. Results: The estimated peak impact forces were reproducible and comparable to those reported in the literature from direct measurements. A one-handed backhand stroke with a short backswing had a significantly shorter contact duration (0.008 ± 0.003 seconds) and a greater peak resultant impact force (330.0 ± 140.7) than that with a long backswing (0.016 ± 0.004 seconds and 180.8 ± 49.1 N). Skill level did not significantly affect the peak resultant impact force. Conclusion: A long backswing in a one-handed backhand stroke may reduce the load on the upper extremity and may assist in reducing the risks of tennis-related upper extremity over-use injuries. J Orthop Sports Phys Ther. 2001;31(5):247-254. Key Words: over-use injury, tennis, upper extremity load

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