Trunk Muscle Activation in Open Stance and Square Stance Tennis Forehands

Electromyography of the trunk muscles were compared between the open and square stance forehand drives of 14 collegiate tennis players. Surface EMG were bilaterally collected from the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) in open and square stance forehand drives. EMG data were transferred by telemetry, 12 bit A/D converted at 1000 Hz, and stored for analysis. Rectified and smoothed EMG data were normalized (NEMG) to maximal isometric voluntary contractions and mean NEMG were calculated during the forward swing and followthrough phases of the stroke. A 2 × 2 × 2 × 6 factorial ANOVA (Gender, Stance, Phase, Muscle) with repeated measures on Subject showed significant (p < 0.05) effects of Gender, Muscle, Phase, and several interactions. The nonsignificant differences in muscle activation between stances did not support the belief of tennis experts that open stance forehands require greater trunk activation than square stance forehands. Mean NEMG of the ES were significantly (p < 0.05) larger than EO or RA, which was consistent with observations of tennis-specific strength imbalances and increasing incidence of low back injuries in tennis.

Abdominal, EMG, erector spinae, external oblique.

References

• 1 Anderson J P. An electromyographic study of ballistic movement in the tennis forehand drive. Unpublished doctoral dissertation. Minneapolis, MN; University of Minnesota 1970
• 2 Ariel G B, Braden V K. Biomechanical analysis of ballistic vs tracking movement in tennis skills. In: Groppel J (ed) A National Symposium on the Racket Sports. Urbana-Champaign, IL; University of Illinois Press 1979: 105-123
• 3 Brody H. How racket technology has changed tennis strokes. Miami, FL; Paper presented to the USTA 2nd National Conference on Sports Medicine and Science in Tennis 1995
• 4 Broer M R, Houtz S J. Patterns of muscular activity in selected sports skills. Springfield, IL; Charles C. Thomas 1967
• 5 Chandler T J. Exercise training for tennis.  Clin Sports Med. 1995;  14 33-46
• 6 Chandler T J, Ellenbecker T S, Roetert E P. Sport-specific muscle strength imbalances in tennis. Strength Cond April, 7. - 10. 1998
• 7 Chu D A. Abdominal muscle pulls in tennis players. Sport Science for Tennis Summer 1996: 4-5
• 8 Elliott B, Marsh T, Overheu P. A biomechanical comparison of the multisegment and single unit topspin forehand drives in tennis.  Int J Sport Biomech. 1989;  5 350-364
• 9 Fein P. Are the new racquets really changing the game?. Tennis Pro May/June 1992: 10-12
• 10 Groppel J. Footwork on the forehand. Sport Science for Tennis Winter 1994: 1
• 11 Groppel J. Injury prevention through proper biomechanics. Miami, FL; Paper presented to the USTA 2nd National Conference on Sports Medicine and Science in Tennis 1995
• 12 Groppel J, Conroy B. The mechanics of the tennis forehand drive: Suggestions for training the tennis player.  Nat Strength Cond Assoc J. 1986;  8 5-10, 79
• 13 Hainline B. Low back injury.  Clin Sports Med. 1995;  14 241-267
• 14 Juker D, McGill S, Kropf P, Steffen T. Quantitative intramuscular myoelectric activity of lumbar portions of the psoas and abdominal wall during a wide variety of tasks.  Med Sci Sports Exerc. 1998;  30 301-310
• 15 Knudson D. Intrasubject variability of upper extremity angular kinematiccs in the tennis forehand drive.  Int J Sport Biomech. 1990;  6 415-421
• 16 Knudson D, Bahamonde R. Trunk and racket kinematics at impact in the open and square stance tennis forehand.  Biology of Sport. 1999;  16 3-10
• 17 Komi P V, Kaneko M, Aura O. EMG activity of the leg extensor muscles with special reference to mechanical efficiency in concentric and eccentric exercise.  Int J Sports Med. 1987;  8 22-29
• 18 Milano S. Should our students be teaching us?. TennisPro Nov. - Dec. 1993: 11
• 19 Ng J KF, Kippers V, Richardson C A. Muscle fibre orientation of abdominal muscles and suggested surface EMG electrode positions.  Electromyogr Clin Neurophysiol. 1998;  38 51-58
• 20 Quinn A M. Abdominal and lower back muscle involvement in selected tennis strokes. Unpublished master's thesis. University of Illinois 1986
• 21 Rasch P J, Burke R K. Kinesiology and Applied Anatomy: The Science of Human Movement. 4th ed. Philadelphia, PA; Lea & Febiger 1971
• 22 Roetert E P, Ellenbecker T S, Chu D A, Bugg B S. Tennis-specific shoulder and trunk strength training. Strength Cond June 1997: 31-39
• 23 Roetert E P, McCormick T J, Brown S W, Ellenbecker T S. Relationship between isokinetics and functional trunk strength in elite junior tennis players.  Isok Exerc Sci. 1996;  6 15-30
• 24 Slater-Hammel A T. An action current study of contraction-movement relationships in the tennis stroke.  Res Q. 1949;  20 424-431
• 25 Sward L, Stevensson M, Zetterberg C. Isometric muscle strength and quantitative electromyography of back muscles in wrestlers and tennis players.  Am J Sports Med. 1990;  18 382-386
• 26 Takahashi K, Elliott B, Noffal G. The role of upper limb segment rotations in the development of spin in the tennis forehand.  Aus J Sci Med Sport. 1996;  28 106-113
• 27 Vint P F, Hinrichs R N. Longer integration intervals reduce variability and improve reliability of EMG derived from maximal isometric exertions.  J Appl Biomech. 1999;  15 210-220