Use of the y-intercept in the evaluation of the anaerobic fitness and performance prediction of trained swimmers

The objective of this study was to verify the use of y-intercept from the critical velocity model in the evaluation of the anaerobic fitness and prediction of maximal performance in trained swimmers in crawl style. Fourteen swimmers with ages ranging from 15 to 18 years participated in this study. The athletes performed the tied swimming test, maximal performances tests and critical velocity (CV) for the determination of anaerobic swimming capacity (AWC). 1) The tied swimming test was applied through maximal effort during 30 seconds fixed to the equipment with load cells for the measurement of the peak force, anaerobic fitness and peak lactate. 2) The subjects also performed maximal performances at distances of 100, 200, 300, 400 and 600 meters with two hours interval between each swim. 3) AWC at CV model was determined utilizing all possible combinations by maximal performances applying the distance-time linear regression model. The AWC value obtained was of 25.07 ± 4.22 m, with linear regression coefficient between 0.99 and 1.00, and linear coefficient error of 19.30 ± 5.9%. AWC was not correlated with all maximal performances, peak force (227.81 ± 63.02 N), anaerobic fitness (85.55 ± 13.05 N), and peak lactate (6.80 ± 1.08 mM). However, the anaerobic fitness was correlated with all maximal performances. Thus, it was concluded that the AWC obtained by y-intercept of the distance/time of swim relation does not seem to be a good parameter for the anaerobic fitness evaluation neither to predict the maximal performances between 100 and 600 meters in crawl style.