Number of Trials Necessary to Achieve Reliable Change-of-Direction Measurement in Amateur Basketball Players

This study examined the inter-day reliability and repeatability of change-of-direction (COD) performance to determine the minimum number of measurement trials required to represent a stable athlete's performance. Twenty-three university basketball players performed seven COD trials. Identical tests were performed two weeks later to evaluate inter-day reliability. Intra-class correlation coefficients were utilised to examine inter-day reliability for all data input methods. Separated ANOVA with repeated measures was performed to examine the trial effect. The ICC analysis indicated that data from the first trial exhibited the lowest reliability and that the fastest trial generally had higher reliability than the mean performance trial. The trial effect results revealed slower COD performance time in the first three trials than in later trials (p < 0.05), with no significant differences amongst later trials. These results suggested that at least four change-of-direction trials are required with respect to improving measurement reliability.