Isokinetic analysis of the volleyball player at the end range of motion

Abstract

Isokinetic analysis of the volleyball player at the end range of motion C. Dupuisa,b, C. Tourny-Cholleta,b and F. Beuret-Blanquarta GRHAL, Faculty of Medicine, University of Rouen, France CETAPS, UPRES JE 2318, Faculty of Sport Sciences, University of Rouen, France This study focuses on the analysis of the rotator muscles of the shoulder of the volleyball player. This interest can be justified by the frequency and the importance of the pathologies of the shoulder of the volleyball player. This joint and the rotator muscles are very solicited by the different techniques like the spike and the serve. The aim of this study was to determine the ratio between agonist and antagonist, supposing that the ratio changes during the whole Range Of Motion (ROM). During the ‘active phase’, the agonist muscles present an concentric activity superior to the eccentric activity of antagonist muscles. Hence the particular attention given to the functional ratio: (agonist concentric/antagonist eccentric) to understand pathologies [1]. Eight volleyball players, eight judokas, and eight non athletes composed the population. An isokinetic dynamometer Kin-Com recorded the experimental data. The subject was sitting, shoulder set in a 90◦ abduction and in the plane of the scapula. The angular velocity was of 90◦/s and the ROM was 110◦ for the tests. The protocol consisted of assessment of Internal Rotator (IR), and External Rotator (ER), in concentric and eccentric modes, for the dominant and non dominant arms. Total ROM and the last 30◦ at either medial or lateral rotations were used. The result indicated no significant difference between the strength of dominant and non dominant shoulder. Among all the assessments, the results of peak torque and mean torque presented no significant difference. The totality of the obtained values of peak and mean torque were significantly superior for the athletes compared to the ones of sedentary subjects (p > 0.05). No significant differences were indicated with respect to either group or ROM (total or partial). For the total ROM, the results of average torque of IR conc and ER ecc are according to literature [2]. On the other hand, the values of IR ecc and ER conc are higher than the results found in the literature. The IR conc/ER conc ratio of reference on whole ROM is 1.5 for the sedentary subjects [3]. These differences of results can be explained by the differences of position of the subject during the assessment [4]. Results of the ratio are not in accord with published findings: 0.52 for the ER conc/IR ecc ratio of the dominant shoulder in the end of ROM [5]. This difference with our results can be explained by the position 90◦/90◦ and the subjects chosen (badminton players). On the other hand, the results of the end of medial rotation are in agreement with the literature: 0.90 for the ER conc/IR ecc ratio [5]. This study underlines the importance of the position of isokinetic test. It means that the ratios are specific of this position. It is of interest to note the small difference between the respective ratios at the medial and lateral ROM.