Background This study used a novel protocol to test the hypothesis that a plateau in oxygen consumption (VO2max) during incremental exercise testing to exhaustion represents the maximal capacity of the cardiovascular system to transport oxygen. Methods Twenty-six subjects were randomly divided into two groups matched by their initial VO2max. On separate days, the reverse group performed (i) an incremental uphill running test on a treadmill (INC1) plus verification test (VER) at a constant workload 1 km h'1 higher than the last completed stage in INC1; (ii) a decremental test (DEC) in which speed started as same as the VER but was reduced progressively and (iii) a final incremental test (INCF). The control group performed only INC on the same days that the reverse group was tested. Results VO2max remained within 0.6 ml kg'1 min'1 across the three trials for the control group (p=0.93) but was 4.4% higher during DEC compared with INC1 (63.9±3.8 vs 61.2±4.8 ml kg'1 min'1, respectively, p=0.004) in the reverse group, even though speed at VO2max was lower (14.3±1.1 vs 16.2±0.7 km h'1 for DEC and INC1, respectively, p=0.0001). VO2max remained significantly higher during INCF (63.6±3.68 ml kg'1 min'1, p=0.01), despite an unchanged exercise time between INC1 and INCF. Conclusion These findings go against the concept that a plateau in oxygen consumption measured during the classically described INC and VER represents a systemic limitation to oxygen use. The reasons for a higher VO2 during INCF following the DEC test are unclear.