Methodological changes to alactic time estimation fail to improve the reliability of the 15-s maximal lactate accumulation rate (V ̇Lamax) test for cycling

Abstract

Blood lactate is used in a variety of ways to optimize performance. Many methods to estimate various aspects of endurance performance have been proposed, including for the estimation of the maximum rate of lactate accumulation ( Lamax). The purpose of this study was to determine if two alternative methods to estimate alactic time improves the reliability of measuring Lamax. Methods: Sixteen men and twelve women completed two sprint sessions over 1-week. After a standardized 10-min warmup, subjects rested passively for 1-min whereupon a 3-µl blood sample was taken to assess baseline blood lactate concentration (BLC).  Subjects then completed a 15-s sprint, and then rested passively while multiple blood samples were taken until blood lactate levels peaked.   Lamax was calculated using either a standard 5-sec alactic time (Talac), or the time to peak power output (TTP). Differences and reliability across trials were analyzed using a paired-sample t-test, and coefficient of variation, Pearson correlation, and intraclass correlation (ICC), respectively; α was set at 0.05 and data are reported as mean ± sd. Results: Power (W) was similar across trials (773.0 ±143.5 vs. 758.2 ± 127.4; p = 0.333) with a CV of 4.7%. Lamax  (mM^.L^-1.s^-1) was similar across trials for Talac (0.727 ± 0.235 vs 0.682 ± 0.237; p = 0.199), and TTP (0.653 ± 0.208 vs. 0.601 ± 0.20; p = 0.201).  Both methods yielded moderate reliability with CV, ICC, and R values of 16.6%, 0.636, and 0.601 for Talac and 18.1%, 0.466, and 0.47 for TTP. Conclusions: 15-s cycling sprint Lamax  remains only moderately reliable even with modified Talac.