A new incremental test for VO_2max accurate measurement by increasing VO_2max plateau duration, allowing the investigation of its limiting factors

The purpose of this study was to (1) validate a new exercise protocol for accurate measurement of VO_2max by obtention of a VO_2max plateau for all subjects fit and unfit (2) test the hypothesis that VO_2max plateau duration is not correlated with VO_2max and (3) verify that limiting factors of VO_2max plateau duration are different from those of VO_2max amplitude. Therefore, 14 subjects performed two incremental cycling tests: (1) a classical incremental test (CIT) to determine VO_2max, the power at VO_2max (PVO_2max) and at the lactate threshold (PLT) (2) a new incremental test (NIT) in which the power was decreased just after the subject reached VO_2max. During both protocols, heart rate, stroke volume, cardiac output, the arterio-venous difference and the oxygen blood saturation were recorded. The results showed that, with the NIT, subject could maintain a long VO_2max plateau (6 ± 3 min), even those who could not reach VO_2max plateau at the end of CIT (n = 5). The VO_2max plateau duration was not correlated with VO_2max amplitude which was correlated with the power at SV_max (r = 0.888, p < 0.001). The VO_2max plateau duration was correlated with the power decrease (W/s) during the VO_2max plateau (r = −0.72, p = 0.003) but not with cardiac-related factors nor with PVO_2max. In conclusion, these experiments showed that it was possible to get a long VO_2max plateau at the end of NIT whatever the individual VO_2max amplitude was. The limiting factor of VO_2max duration was the power output.