RELIABILITY AND FACTORIAL VALIDITY OF AGILITY TESTS FOR SOCCER PLAYERS GORAN SPORIS,IGOR JUKIC,LUKA MILANOVIC, AND VLATKO VUCETIC Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia ABSTRACT Sporis, G, Jukic, I, Milanovic, L, and Vucetic, V. Reliability and factorial validity of agility tests for soccer players. J Strength Cond Res 24(3): 679–686, 2010—The purpose of this study was to evaluate the reliability and factorial validity of agility tests used in soccer. One hundred fifty (n = 150), elite, male, junior soccer players, members of the First Junior League Team, volunteered to participate in the study. The slalom test (ST) sprint 4 3 5 m (S4 3 5) and sprint 9-3-6-3-6-9 m with 180° turns (S180°) tests had a greater reliability coefficient (a = 0.992, 0.979, and 0.976), whereas the within-subject variation ranged between 2.9 and 5.6%. The mentioned 6 agility tests resulted in the extraction of 2 significant components. The S435 test had the lowest correlation coefficient with the first component (r = 0.38), whereas the correlation coefficients of the other 5 agility tests were higher than 0.63. The T-test (TT) showed statistically significant differences between the defend- ers and midfielders (p , 0.05) and between the defenders and attackers (p , 0.05). Statistical significant differences were determined between the attackers and defenders in the sprint 9-3-6-3-9 m with backward and forward running (SBF) and p , 0.05. It can be concluded that of the 6 agility tests used in this study, the SBF, TT, and S180° are the most reliable and valid tests for estimating the agility of soccer players. According to the results of the study, the TT proved to be the most appropriate for estimating the agility of defenders, the SBF, and S180° for estimating the agility of midfielders, whereas the S4 3 5 test can be used for estimating the agility of attackers. KEY WORDS field tests, evaluation, junior players INTRODUCTION A gility is the ability to maintain and control correct body positions while quickly changing direction through a series of movements (22). Agility training has, for a long time, been a component of every soccer training program but it has not been well investigated scientifically. A soccer player changes direction every 2–4 seconds (23) and makes 1,200–1,400 changes (2) of direction during a game. Players and coaches alike are continually looking for ways to help athletes gain a compet- itive edge in soccer. Agility is believed to be an important physical component necessary for successful performance in many sports, particularly in soccer (8,10,11,19). It is also fundamental for the optimal performance of soccer players and often described as a quality possessing the ability to change direction and start and stop quickly (3,9,16,18). Improving agility is one of the most important aspects of the off-season strength and conditioning programs. In soccer, there is a strong interest present in developing a field test that could effectively measure the agility of soccer players. In a game situation, the changes of directions may be initiated to either pursue or evade an opponent or react to the moving ball. Therefore, it has been recognized that the response to a stimulus (4) is a component of agility performance. However, scientists differ on how to define agility, and only a small number of articles deal with the problem of agility tests (20). From a soccer perspective, we might add that agility is also the ability to change directions quickly and easily. Further- more, agility, conditioning, and weight training need to be synchronized in reference to periodization. By working on agility and by improving balance and coordination, soccer players will be able to move faster and change directions more quickly while maintaining control. Enhanced power, balance, speed, and coordination are some of the objectives of their agility training. Sport scientists continually search for effective methods to identify physical characteristics that may contribute to sport performance. A common method of assessing the athletic talent is through physical ability testing (5). Agility tests can help soccer coaches and conditioning specialists diagnose specific weaknesses, screen for possible health risks due to strenuous exercise, provide data for outlining individual exercise prescriptions, and assess cycles of a training period (1). Although there is no consensus on the measurement of agility, in soccer, the T-test (TT) is very Laboratory: Sports Diagnostic Centre of the Faculty of Kinesiology. Address correspondence to Goran Sporis, gsporis@kif.hr. 24(3)/679–686 Journal of Strength and Conditioning Research Ó 2010 National Strength and Conditioning Association VOLUME 24 | NUMBER 3 | MARCH 2010 | 679