Oxygen uptake plateau occurrence depends on oxygen kinetics and oxygen deficit accumulation

We tested the hypothesis that participants with an oxygen uptake ( V ˙ O 2 ) plateau during incremental exercise exhibit a lower VO 2 ‐deficit (VO 2DEF )‐accumulation in the submaximal intensity domain due to faster ramp and square wave O 2 ‐kinetics. Twenty‐six male participants performed a standard ramp test (increment: 30 W·min −1 ), a ramp test with an individualized ramp slope and a two‐step (moderate and severe) square wave exercise followed by aV ˙ O 2 m a x‐verification bout. VO 2DEF was calculated by the difference between individualized ramp test V ˙ O 2 and V ˙ O 2 ‐demand estimated from steady‐state V ˙ O 2 ‐kinetics. Twenty‐four participants verified their V ˙ O 2max in the verification test. Ten of them showed a plateau in the individualized ramp test. VO 2DEF at the end of this ramp test (4.34 ± 0.60 vs 4.54 ± 0.43 L) was not different between the plateau and the non‐plateau group ( P  > 0.05). The plateau group had a significantly ( P  < 0.05) lower VO 2DEF 2 minutes before termination of the individualized ramp test (2.24 ± 0.40 vs 2.78 ± 0.33 L). This coincided with a shorter mean response time (43 ± 9 vs 53 ± 7 seconds), a higher increase in V ˙ O 2 per W (10.1 ± 0.2 vs 9.2 ± 0.5 mL·min −1 ·W −1 ) at the individualized ramp test as well as shorter time constants of moderate (36 ± 6 vs 48 ± 7 seconds) and severe (62 ± 9 vs 86 ± 10 seconds) square wave kinetics (all P  < 0.05). We conclude that the V ˙ O 2 ‐plateau occurrence requires a fast V ˙ O 2 ‐kinetics and a low VO 2DEF ‐accumulation at intensities below V ˙ O 2max .