| Popis: |
The purpose of this study was to determine the efficacy of a two-test method for precisely identifying the Maximal Lactate Steady State (MLSS). Eight male competitive cyclists performed two bouts on a cycle ergometer. Following a maximal oxygen consumption (V̇O2max) test (66.91 ± 5.29 mL·kg−1·min−1) we identified the lactate deflection point using the visual deflection (TVis), Log-Log (TLog), Dmax (TDmax), RER = 1.00 (TRER), ventilatory threshold (TVent), and the 1.0 mmol·L−1 increase above baseline (T+1) methods. The second incremental test (SIT) consisted of 6–7 stages (5 min each) starting 20–30 W below to 20–30 W above the predetermined deflection point, in 10 W increments. Comparison of the two tests yielded different threshold estimates (range 11–46W) for all methods (P = 0.001–0.019) except the TLog (P = 0.194) and TRER (P = 0.100). The SIT resulted in significantly (P = 0.007) more narrow range of thresholds (27.5 ± 11.01W) compared to the V̇O2max test (70 ± 42.51W). The TVis from the SIT was identified as the MLSS and was verified using three 45-minute steady-state exercise bouts at 95%, 100%, and 105% of MLSS intensity (average increment 12.8 W). Blood lactate and V̇O2 were recorded every 5 minutes and differed between the three intensities at every time point (P < 0.001). V̇O2 increased from the 5th to the 45th minute by 7.02 mL·kg−1·min−1 (100% MLSS), 3.63 mL·kg−1·min−1 (95% MLSS) and 7.5 mL·kg−1·min−1 (105% MLSS, to the 30th minute). These results indicate that the MLSS was identified correctly by the SIT, the single incremental test overestimated the MLSS intensity, and the TVis provides a very accurate determination of the lactate breakpoint. The use of a second submaximal test is required for a precise identification of MLSS. |
