Abstract Discussion: FATIGUE-RESISTANCE OF THE INTERNAL ROTATOR MUSCLES IN THE TENNIS PLAYER'S SHOULDER: ISOKINETIC AND ELECTROMYOGRAPHIC ANALYSIS

Submitted by Michael Griesser, MD

Phys Ther Sport. 2012 Feb;13(1):22-6. Epub 2011 Apr 8.

FATIGUE-RESISTANCE OF THE INTERNAL ROTATOR MUSCLES IN THE TENNIS

PLAYER'S SHOULDER: ISOKINETIC AND ELECTROMYOGRAPHIC ANALYSIS

Julienne R,Gauthier A, Davenne D.

SOURCE:

INSERM, ERI 27, Université de Caen-Basse-Normandie, Caen F-14000, France. roland.julienne@yahoo.fr

ABSTRACT

OBJECTIVE:

The main objective is to determine whether there are differences in the relative isokinetic and electromyographic responses between the internal rotator (IR) muscles on the dominant and non-dominant sides of tennis players during performance of an isokinetic fatigue protocol.

MAIN OUTCOME MEASURES:

Ten male tennis players were recruited for this isokinetic and electromyographic study. Participants performed 35 concentric maximal voluntary actions, carrying out internal rotations of both shoulders at an angular velocity of 120° s(-1). Maximal torque (T((45°))Max), torque decrease (T((45°))), Root Mean Square normalized (RMS norm) and Neuromuscular Efficiency (NME) parameters were analyzed.

RESULTS:

Although an increased T((45°))Max was observed on the dominant side compared to the non-dominant side, the progression of torque differences did not indicate differences in fatigue-resistance between the two sides. RMS norm was also higher on the dominant side compared to the non-dominant side, without showing a fatigue effect. NME values decreased during performance of the fatigue protocol without any side effect.

CONCLUSIONS:

Practicing tennis induces an increased T((45°))Max on the dominant side compared to the non-dominant side, but does not appear to provoke differences in the fatigue-resistance of IR muscles. EMG analysis showed that the fatigue induced was mainly peripheral (from metabolic and ionic changes).

REVIEW:

This study showed that there is no difference in fatigue-resistance of shoulder internal rotators between the dominant and non-dominant arms. Furthermore, EMG responses show that the observed torque decreases with fatigue were mostly due to peripheral fatigue (excitation-contraction coupling in the muscles mediated by metabolic and ionic changes). This provides us with insight into the most effective conditioning programs for tennis player’s shoulders, which would focus on delaying this peripheral fatigue with fatigue-resistance training

protocols.