Tennis players show a lower coactivation of the elbow antagonist muscles during isokinetic exercises

Purpose: Previous studies have suggested that muscle coactivation could be reduced by a recurrent activity (training, daily activities). If this was correct, skilled athletes should show a specific muscle activation pattern with a low level of coactivation of muscles which are typically involved in their discipline. In particular, the aim of this study was to verify the hypothesis that the amount of antagonist activation of biceps brachii (BB) and triceps brachii (TB) is different between tennis players and non-players individuals during maximal isokinetic contractions. Methods: Ten young healthy men and eight male tennis players participated in the study. The surface electromyographic signals (sEMG) were recorded from the BB and TB muscles during three maximal voluntary isometric contractions (MVC) of elbow flexors and extensors and a set of three maximal elbow flexions and extensions at 15 degrees, 30 degrees, 60 degrees, 120 degrees, 180 degrees and 240 degrees/s. Normalized root mean square (RMS) of sEMG was calculated as an index of sEMG amplitude. Results: Antagonist activation (%RMSmax) of TB was significantly lower in tennis players (from 14.0 +/- 7.9% at MVC to 16.3 +/- 8.9% at 240 degrees/s) with respect to non-players (from 27.7 +/- 19.7% at MVC to 38.7 +/- 17.6% at 240 degrees/s) at all angular velocities. Contrary to non-players, tennis players did not show any difference in antagonist activation between BB and TB muscles. Conclusions: Tennis players, with a constant practice in controlling forces around the elbow joint, learn how to reduce coactivation of muscles involved in the control of this joint. This has been shown by the lower antagonist muscular activity of triceps brachii muscle during isokinetic elbow flexion found in tennis players with respect to non-players. (C) 2007 Elsevier Ltd. All rights reserved.