Relationships Between The Yo-Yo Intermittent Recovery Test Level 2 And Match-Running Performance Vary Between Playing Positions In Elite Under-14 Soccer Players

The aim of the present study was to examine the relationships between the Yo-Yo intermittent recovery test level 2 (YYIR2) and match-running performance across playing position in elite young soccer players.Participants were 142 players from 14 professional soccer academy under-14 teams.Twenty-six 11-a-side matches were analyzed using a Global Positioning System.Total distance, distance covered by sprinting (> 5.3 m•s -1 ), distance covered at very high-intensity activity (VHIA, ≥ 4.5 m•s -1 ), distance covered above maximal power (MaxP, > 55 W•kg -1 ) and metabolic power greater than or equal to 35 W•kg -1 (MP≥35), and acceleration (> 2 m•s -2 , NA>2) and deceleration (< 2 m•s -2 , ND<2) frequencies were computed.The YYIR2 test was conducted within three weeks of the matches.When all players were included, the YYIR2 distance was positively related to all match-running performance variables (r = 0.31-0.49,all P < 0.01).When the analysis was conducted on individual playing positions, the YYIR2 distance demonstrated: positive relationships with total distance in defenders and central midfielders (r = 0.42-0.63,all P < 0.05); positive relationships with sprinting, VHIA, MaxP and MP≥35 distance and NA>2 in all playing positions (r = 0.41-0.71,all P < 0.05); and positive relationships with ND<2 in central midfielders (r = 0.55, P = 0.005).The present results indicate that the YYIR2 is a valid test for the assessment of match-related physical fitness in elite young soccer players across playing position.However, the relationships between the YYIR2 and match-running performance variables are playing position-dependent except for match-running distance at high-speeds and high-metabolic powers and NA>2.