Validade e confiabilidade de um sensor inercial de baixo custo para avaliação cinemática de membros inferiores em atletas de voleibol

Abstract

Volleyball is a sport in which the height of the jump is one of the main performance criteria, jumps are used during the fundamental of lifting, serving, blocking and attacking, representing about 60% of the actions in the game. Studies have investigated the kinematics of jumping in volleyball, through 3D analysis and this has been used in training and monitoring the actions of athletes in different sports. However, there are still some limitations to its use, such as high cost and low portability, which makes these analyzes to be performed in laboratory environments. Such limitations have recently conducted research using inertial sensors, these are portable and have the advantage of wireless technology, which allows the acquisition of data outside the laboratory environment. In order to resolve issues such as low portability and greater ecological validity, the objective of the present study is to verify the concurrent validity and reliability of the low-cost inertial sensor in the knee kinetic flexion-extension measurements in volleyball athletes during the performance of the countermovement jump (SCM) and lateral displacement block jump (SBDL). Nine male volleyball athletes participated in the sub 17 category. For the evaluation of the maximum knee flexion and extension measures, SCM and SBDL were used, and 11 cameras and five inertial sensors were used. The validity between the instruments by the Bland-Altman procedure, the reliability was calculated by the intraclass correlation coefficient (ICC2.1) and the standard error of the measure (EPM). In all analyzes, the level of significance was 5%. The concurrent validity of the values obtained by the cameras and sensors, was through the Bland-Altman dispersion graph, in all analyzes the bias was not significant by the single sample t test. The ICC results were significant and considered excellent (values > 0.75) and small EPM values, for all jumps. The results show that inertial sensors are valid and reliable to characterize the knee flexion-extension movement in SCM and SBDL, these sensors prove to be relatively inexpensive equipment compared to those available on the market, and with an experimental protocol that is more viable for use in the sports environment compared to 3D kinematic analysis.