Reliability and usefulness of the reaction speed test in young female volleyball players

Reaction speed represents a crucial ability to achieve a high-performance level in volleyball. A reliable computerized test for assessing reaction speed cannot simulate the dynamic environment of the volleyball game. Therefore, tests involving the activation of large muscle groups are needed. This study aimed to determine the reliability of young volleyball players' reaction speed ability using the Stopping the rolling ball test (SRB). Intraclass correlation coefficient (ICC), standard error of measurement (SEM) also expressed as a coefficient of variation (CV%), smallest worthwhile change (SWC), and minimal detectable change (MDC) were calculated. Paired t-test revealed no significant differences between test and re-test for first (t = -0.09, p = 0.92), mean of three (t = -0.37, p = 0.71), and best of three (t = -0.02, p = 0.98) trials. The ICC values showed poor relative reliability when the first trial was observed, while for the mean and best of three trials, reliability was consistently very high (excellent). The absolute reliability parameters (within-individual variation) showed large variations ranging from 5% to almost 10% and greater SEM (12.63 cm) for first trial when compared to other variables. The SEM was higher than SWC for all variables when the small differences (i.e., 0.2 multiplied by between-participants SD) were considered. This test showed a high level of absolute and relative reliability and usefulness, which means that the SRB test is an excellent indicator of reaction speed in young volleyball players.