Assessment of Critical Velocity and Blood Lactate in Pre-Pubertal Swimmers

Abstract

0824 Critical velocity (CV) in swimming represents the speed that can be theoretically maintained indefinitely without exhaustion and has been suggested as a marker of endurance ability. Previous investigations have found high correlations between CV and the anaerobic threshold but also differences between the corresponding velocities. PURPOSE: The aims of the study were 1) to investigate different performance models for the determination of CV and 2) to test the hypothesis that CV identifies an exercise intensity without net lactate production in pre-pubertal male swimmers. METHODS: Data were collected from 7 boys (mean ± SD age 10.5 ± 1.1yr; height 1.41 ± 0.08m and weight 32.6 ± 6.8kg) during 4 maximal front crawl time trials (54.8m, 109.7m, 219.4m and 438.7m) with blood lactate measurements pre and post each trial. CV was determined for each subject by regression analysis using the distance-time model [Distance = ASC + (CV × Time)] and velocity-1/time model [Velocity = CV + (ASC × 1/Time)], where ASC is the Anaerobic Swimming Capacity. The velocity with zero net lactate accumulation was determined based on the interrelationship between swimming velocity and lactate appearance rate (lactate/velocity model). RESULTS: A within subject ANOVA analysis revealed no significant differences between the CV and the goodness of fit (R2) for the distance-time model, (CV = 0.67 ± 0.08 m.s−1, R2 = 1.00 ± 0.001), the velocity-1/time model (CV = 0.68 ± 0.06 m.s−1, R2 = 0.94 ± 0.10), and the lactate/velocity model (CV = 0.70 ± 0.07, r2 0.94 ± 0.08). CONCLUSION: The results demonstrate that 1) the application of the tested models did not generate differences in CV and 2) identified an intensity domain without net lactate appearance. Assessment of critical velocity provides a practical, inexpensive and non-invasive method for determining endurance ability in male pre-pubertal swimmers.