The Decremental Protocol as an Alternative Protocol to Measure Maximal Oxygen Consumption in Athletes

To determine whether a decremental protocol could elicit a higher maximal oxygen consumption (VO₂max) than an incremental protocol in trained participants. A secondary aim was to examine whether cardiac-output (Q) and stroke-volume (SV) responses differed between decremental and incremental protocols in this sample.

Nineteen runners/triathletes were randomized to either the decremental or incremental group. All participants completed an initial incremental VO₂max test on a treadmill, followed by a verification phase. The incremental group completed 2 further incremental tests. The decremental group completed a second VO₂max test using the decremental protocol, based on their verification phase. The decremental group then completed a final incremental test. During each test, VO₂, ventilation, and heart rate were measured, and cardiac variables were estimated with thoracic bioimpedance. Repeated-measures analysis of variance was conducted with an alpha level set at .05.

There were no significant main effects for group (P = .37) or interaction (P = .10) over time (P = .45). VO₂max was similar between the incremental (57.29 ± 8.94 mL · kg^-1 · min^-1) and decremental (60.82 ± 8.49 mL · kg^-1 · min^-1) groups over time. Furthermore, Q and SV were similar between the incremental (Q 22.72 ± 5.85 L/min, SV 119.64 ± 33.02 mL/beat) and decremental groups (Q 20.36 ± 4.59 L/min, SV 109.03 ± 24.27 mL/beat) across all 3 trials.

The findings suggest that the decremental protocol does not elicit higher VO₂max than an incremental protocol but may be used as an alternative protocol to measure VO₂max in runners and triathletes.