The Reliability of a Single-Trial Measurement of Maximal Accumulated Oxygen Deficit Determined via Perceptually-Regulated Exercise.

Purpose: The aim of this study was to evaluate the reliability of a single-trial determination of maximal accumulated oxygen deficit (MAOD) achieved via the aid of perceptually-regulated incremental exercise. Methods: 14 trained male cyclists (age: 45 ± 8 yrs; height: 1.82 ± 0.06 m; mass: 79.7 ± 6.7 kg; $\dot{V}{O}_{2\max }$: 4.09 ± 0.57 L·min^-1) performed three trials of a submaximal incremental cycling test followed by a test to exhaustion at 116% of predicted $\dot{V}{O}_{2\max }$. The intensity for each stage of the incremental test was regulated by participants to elicit perceived exertion levels of 9-15 on the Borg (6-20) scale. Linear regression was used to estimate $\dot{V}{O}_{2\max }$ at a perceived exertion level of 19. MAOD was calculated from the difference between predicted and actual oxygen demand in the test to exhaustion, reported in oxygen equivalents (O₂ eq). A separate incremental test was used to measure $\dot{V}{O}_{2\max }$ directly. Results: Correlation coefficients between perceived exertion and $\dot{V}{O}_2$ across trials were strong (r ≥0.99), and there were no between-trial differences in predicted $\dot{V}{O}_{2\max }$ (4.03 ± 1.04, 3.76 ± 0.53, and 3.69 ± 0.64 L·min^-1, respectively; p = .142) or MAOD (2.75 ± 2.28, 2.50 ± 1.53, and 2.93 ± 1.40 L O₂ eq, respectively; p = .633). Nevertheless, the coefficients of variation for predicted $\dot{V}{O}_{2\max }$ (14.2%) and MAOD (142.8%) were poor. Conclusions: The prediction of $\dot{V}{O}_{2\max }$ from perceptually-regulated exercise displays a level of test-retest reliability which prevents its use as a means of evaluating MAOD reliably in a single-trial.