The objective of this study was to compare the critical speed (CS) determined from different distances with the anaerobic threshold (AnT) and the maximum speeds in tests of 20 (S20) and 30 (S30) minutes, and to check if the chronological age of young swimmers can influence these relations. 31 swimmers (17 girls and 14 boys) participated in this study, divided by chronological age into two groups: 10-12 and 13-15 years. The AnT was determined as the velocity corresponding to 4 mM of blood lactate. The CS1 (25/50/100 m), CS2 (100/200/400 m), and the CS3 (50/100/200 m) had been calculated through the slope of the linear regression between the distances and their respective times. The S20 and S30 were determined through 3 to 6 trials, with blood collections at the 10th min and at the end of each test. For the 10-12 group, CS1 (m/s) (0.98 + 0.17) and AnT (0.97 + 0.12) were not different, being higher than CS2 (0.92 + 0.16), CS3 (0.89 + 0.18), S20 (0.92 + 0.11) and S30 (0.90 + 0.11). For the 13-15 group, CS1 (m/s) (1.11 + 0.11) was higher than AnT (1.02 + 0.07), S20 (0.99 + 0.09), S30 (0.97 + 0.09), CS2 (0.98 + 0.11) and CS3 (1.00 + 0.11). It can be concluded that the distance used for the determination of CS interferes on its value, irrespective of the chronological age. CS determined with distances between 50 and 400 m can be used for evaluation of the aerobic capacity of children and adolescents, substituting the maximum continuous tests of 20 or 30 minutes.
Anaerobic threshold; Critical speed; Lactate; Children; Swimming
