Sub-maximal and maximal Yo-Yo intermittent endurance test level 2: heart rate response, reproducibility and application to elite soccer

The aims of this study were to (1) determine
the reproducibility of sub-maximal and maximal versions
of the Yo–Yo intermittent endurance test level 2 (Yo–Yo
IE2 test), (2) assess the relationship between the Yo–Yo
IE2 test and match performance and (3) quantify the sensitivity of the Yo–Yo IE2 test to detect test–retest changes
and discriminate between performance for different playing standards and positions in elite soccer. Elite (n = 148)
and sub-elite male (n = 14) soccer players carried out the
Yo–Yo IE2 test on several occasions over consecutive
seasons. Test–retest coefficient of variation (CV) in Yo–Yo
IE2 test performance and heart rate after 6 min were 3.9%
(n = 37) and 1.4% (n = 32), respectively. Elite male
senior and youth U19 players Yo–Yo IE2 performances
were better (P\0.01) than elite youth U16s and sub-elite
players (2,603 ± 451 and 2,534 ± 549 vs. 1,855 ± 535
vs. 1,749 ± 382 m). The intra- and inter-season CV for
Yo–Yo IE2 test performance were 4.2 and 5.6%, respectively. A correlation was observed (P\0.05) between
Yo–Yo IE2 test performance and the total (r = 0.74) and
high-intensity (r = 0.58) running distance covered in a
match. A correlation was also evident (P\0.01) between
Yo–Yo IE2 test heart rate after 6 min expressed in
percentage of maximal heart rate and the peak values for
high-intensity running performed by midfielders in 5-min
(r = -0.71), 15-min (r = -0.75) and 45-min periods
(r = -0.77). The present data demonstrate that the Yo–Yo
IE2 test is reproducible and can be used to determine the
capacity of elite soccer players to perform intense intermittent exercise. Furthermore, the Yo–Yo IE2 test was
shown to be a sensitive tool that not only relates to match
performance but can also differentiate between intermittent
exercise performance of players in various standards,
stages of the season and playing positions.