Metabolic and Cardiorespiratory Responses of Semiprofessional Football Players in Repeated Ajax Shuttle Tests and Curved Sprint Tests, and Their Relationship with Football Match Play.

In this study, the Ajax Shuttle Test (AST) and the Curved Sprint Test (CST) were conducted on semiprofessional football players to evaluate (1) their test performance, (2) the extent of anaerobic glycolysis by measuring blood lactate, (3) performance decrement and onset of fatigue, and (4) the correlation between selected physiological variables and test performance. Thirty-two semiprofessional Polish football players participated in this study. Both AST and CST were conducted on an outdoor football ground and were conducted in two sets; each set had six repetitions. In the case of AST, the total duration for 6 repetitions of the exercise in Sets 1 and 2 were 90.63 ± 3.71 and 91.65 ± 4.24 s, respectively, whereas, in the case of CST, the respective values were 46.8 ± 0.56 and 47.2 ± 0.66 s. Peak blood lactate concentration [La] after Sets 1 and 2 of AST were 14.47 ± 3.77 and 15.00 ± 1.85 mmol/L, and in the case of CST, the values were 8.17 ± 1.32 and 9.78 ± 1.35 mmol/L, respectively. Performance decrement in AST was more than in CST, both after Set 1 (4.32 ± 1.43 and 3.31 ± 0.96 in AST and CST, respectively) and Set 2 (7.95 ± 3.24 and 3.71 ± 1.02 in AST and CST, respectively). Only in a few of the repetitions, pulmonary ventilation (V