This study aimed to compare physiological responses during rowing ergometer exercise at the maximal lactate steady state (MLSS) and 5% above the MLSS (MLSS+5%). Blood lactate concentration (BLC), oxygen uptake (VO2) kinetics, heart rate (HR), and muscle oxygenation (deoxygenated hemoglobin [HHb] and tissue saturation index [TSI]) of the vastus lateralis were compared. Twelve male rowers (VO2max: 53.0 ± 6.3 mL·kg-1·min-1) completed an incremental test and several 30-min constant workload tests to determine their MLSS and MLSS+5%. At the 30th minute, exercise at MLSS+5% (195 ± 25 W) resulted in significantly higher BLC (5.02 ± 1.44 vs. 3.07 ± 1.03 mmol·L-1), VO2 (3.56 ± 0.35 vs. 3.33 ± 0.33 L·min-1), HR (177 ± 11 vs. 166 ± 10 bpm), and [HHb] (83.9 ± 16.9 vs. 72.7 ± 13.2%) compared to MLSS (185 ± 24 W) (p < 0.05). No VO2 slow component was observed during either the MLSS or MLSS+5% trials. In conclusion, while exercise 5% above MLSS induced a non-sustainable BLC response, there was no apparent VO2 slow component and [HHb] remained stable in the vastus lateralis during rowing exercise.
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