Physiological determinants of Yo-Yo intermittent recovery tests in male soccer players

The physiological determinants of performance in two Yo-Yo intermittent recovery tests (Yo-YoIR1 and Yo-YoIR2) were examined in 25 professional (n = 13) and amateur (n = 12) soccer players. The aims of the study were (1) to examine the differences in physiological responses to Yo-YoIR1 and Yo-YoIR2, (2) to determine the relationship between the aerobic and physiological responses to standardized high-intensity intermittent exercise (HIT) and Yo-Yo performance, and (3) to investigate the differences between professional and amateur players in performance and responses to these tests. All players performed six tests: two versions of the Yo-Yo tests, a test for the determination of maximum oxygen uptake ((V)over dot O(2max)), a double test to determine (V)over dot O(2) kinetics and a HIT evaluation during which several physiological responses were measured. The anaerobic contribution was greatest during Yo-YoIR2. (V)over dot O(2max) was strongly correlated with Yo-YoIR1 (r = 0.74) but only moderately related to Yo-YoIR2 (r = 0.47). The time constant (tau) of (V)over dot O(2) kinetics was largely related to both Yo-Yo tests (Yo-YoIR1: r = 0.60 and Yo-YoIR2: r = 0.65). The relationships between physiological variables measured during HIT (blood La(-), H(+), HCO(3)(-) and the rate of La(-) accumulation) and Yo-Yo performance (in both versions) were very large (r > 0.70). The physiological responses to HIT and the tau of the (V)over dot O(2) kinetics were significantly different between professional and amateur soccer players, whilst (V)over dot O(2max) was not significantly different between the two groups. In conclusion, (V)over dot O(2max) is more important for Yo-YoIR1 performance, whilst tau of the (V)over dot O(2) kinetics and the ability to maintain acid-base balance are important physiological factors for both Yo-Yo tests.