Untitled

Abstract

The aims of the study were to determine validity of the K-test and to determine reliability, usefulness, and responsiveness. The research study involved a total of 98 football players in the U17 and U19 categories from Czech Republic (men; age 16.9 ± 1.3 years, height = 177.1 ± 4.6 cm, weight = 68.7 ± 4.6 kg). The speed and agility K-test was applied. The time was measured by electronic timing gates. The high intraclass correlation coefficient value (ICC = 0.89; 90% CI: [0.83, 0.93]) implies a very high level of intra-rater reliability. The value only 0.10 s (0.092-0.13 s) for standard error of measurement was found and therefore the coefficient of variation was 0.93 % (0.85-0.95 %). The smallest worthwhile change was 0.29, thus 2.68 %. The results of t test (t0=0.24) comparing third and fourth (after intervention) ratified null hypothesis about size of intervention effect to K-test results, and smallest worthwhile change was 0.02. This study showed empirical support to the construct validity of K-test as indicators of match-related physical performance in top level professional football players. We consider K-test to be practical, specific, reliable, valid, and useful test to evaluate agility performance of football players.