In order to reduce athlete testing time, the aim of this study was to investigate the relationship between the Yo-Yo intermittent recovery test level 1 (IR1) and 2 (IR2) test performances, maximal sprinting speed (10, 20 and 35 m), repeated sprint ability (RSA) (7x35 m), and sub-maximal heart rates after two and four minutes of the Yo-Yo IR tests by testing 57 high-level soccer players. All players played regularly in one of the three highest levels of Norwegian soccer and were tested during three sessions on three consecutive days. Large correlations were observed between Yo-Yo IR1 and IR2 test performances (r=0.753 p≤0.05). Small and moderate correlations were found between 20 and 35 m sprinting speed and Yo-Yo IR1 performance (r=-0.289 and -0.321, respectively, p≤0.05), while 35 m sprinting speed correlated moderately to Yo-Yo IR2 performance (r=-0.371, p≤0.05). RSA at 10, 20 and 35 m all showed moderate to large correlations to Yo-Yo IR1 performance (r=-0.337 to -0.573, p≤0.05). RSA at 20 m (r = -0.348, p≤0.05) and 35 m (r=-0.552, p≤0.01) correlated moderately and largely to Yo-Yo IR2 performance. Also, moderate and large correlations were found between sub-maximal Yo-Yo IR1 heart rates after 2 (r=-0.483, p≤0.01) and 4 min (r=-0.655, p≤0.01) and Yo-Yo IR1 performance, and 2 min Yo-Yo IR2 heart rate and Yo-Yo IR2 performance (r=-0.530, p≤0.01). ICC measures of sub-maximal HR after 2 and 4 min of Yo-Yo IR1 test, and after 2 min of the Yo-Yo IR2 were 0.92 (CV=4.1%, n=33), 0.93 (CV=3.8%, n=33) and 0.72 (CV=2.9%, n=10). Adjusted ordinary least square (OLS) regressions revealed associations (p≤0.05) between sprint speed at 20 m and 35 m and Yo-Yo IR1 test performance, but only between 35 m and IR2 test performance (p≤0.05). Further, OLS showed that RSA at 35 m was related to both levels of the Yo-Yo IR test (p≤0.01), and that sub-maximal heart rates after 2 and 4 min were independently associated to Yo-Yo IR1 and IR2 performances (p≤0.01). In conclusion, Yo-Yo IR1 and 2 test performances, as well as sprint and RSA performances, correlated very largely, and it may therefore be considered using only one of the Yo-Yo tests and a RSA test, in a general soccer-specific field test protocol. The sub-maximal heart rate measures during Yo-Yo tests are reproducible and may be utilized for frequent, time-efficient and non-exhaustive testing of intermittent exercise capacity of high-level soccer players.
Journal of Strength and Conditioning Research, 2014, Vol 28, Issue 4, p. 942-949