engleski

Reliability and validity of the newly developed tests of football specific change of direction speed and reactive agility in youth players

Purpose: Agility is an important determinant of success in football (soccer), but there is a lack of reliable and valid tests applicable in the evaluation of different agility components in youth football players. In this study we evaluated the reliability and factorial validity of the two newly developed tests of agility in male youth football players. Methods: The sample comprised 44 youth football players (all males, 14-15 years of age) who were tested on anthropometrics (body height and mass), newly developed tests of football specific reactive agility (FS-RAG) and change of direction speed (FS-CODS), one standard test of CODS (20- yards), and sprinting over 20-m distance (S20M). The relative reliability is evaluated by calculation of Intra-Class- Correlation coefficients (ICC), while the absolute reliability was evaluated by calculation of the coefficient of variation (CV). Further, systematic bias was checked by analysis of variance for repeated measurements (ANOVA). The associations between studied variables were evidenced by Pearson’s correlation. Finally, factor analysis was calculated to define the factorial validity of agility tests (FS-RAG, FS- CODS, 20-yards). Results: The newly developed football-specific tests were found to be reliable, with better reliability of FS-CODS (ICC: 0.81, CV: 6%), than of FS-RAG (ICC: 0.76, CV: 9%). The ANOVA evidenced significant (p < 0.05) learning effects for FS-RAG, but post-hoc analysis indicated stabilization of the results until the third testing trial. Factor analysis extracted one significant factor under the Guttmann-Kaiser criterion (Explained Variance: 1.67), showing the appropriate factorial validity of newly developed tests in comparison to standard agility indicator 20-yards. Meanwhile, the significant correlations between all agility performances with S20M (Pearson’s R: 0.52-0.63 ; all p < 0.01) revealed that sprinting capacity significantly influence agility performances and that conditioning capacities of youth football players are not yet discriminated. Conclusion: Results showed appropriate reliability and validity of the newly developed tests of football specific change of direction speed and reactive agility. Therefore, here proposed FS-CODS and FS- RAG can be used as reliable and valid measures of agility components in youth football players. Further studies should evaluate the discriminative validity of the here proposed tests (i.e. identification of position- specific or performance-related differences), as well as reliability in younger players than those studied herein.

soccer ; agility ; sport-specific tests ; reliability ; validity

nije evidentirano