The exercise intensity at maximal oxygen uptake (i⩒O_2max): Methodological issues and repeatability

The minimum exercise intensity that elicits ⩒O_2max (i⩒O_2max) is an important variable associated with endurance exercise performance. i⩒O_2max is usually determined during a maximal incremental exercise test; however, the magnitude and duration of the increments used influence the i⩒O_2max value produced by a given test. The aims of this study were twofold. The first was to investigate whether the i⩒O_2max value produced by a single cycle ergometer test (i⩒O_2max(S)) was repeatable. The second was to determine if i⩒O_2max(S) represents the minimum intensity at which ⩒O_2max is elicited when compared to a refined i⩒O_2max value (i⩒O_2max(R)) derived from repeated tests. Seventeen male cyclists (age 33.9 ± 7.7 years, body mass 80.9 ± 10.2 kg, height 1.82 ± 0.05 m; VO_2max 4.27 ± 0.62 L min⁻¹) performed four maximal incremental tests for the determination of i⩒O_2max(S) and i⩒O_2max(R) (3 min stages; 20 W increments). Trials 1 and 2 were identical and used for assessing the repeatability of i⩒O_2max(S), trials 3 and 4 began at different intensities and were used to determine i⩒O_2max(R). i⩒O_2max(S) showed good test–retest repeatability for i⩒O_2max (CV = 4.1%; ICC = 0.93), VO_2max (CV = 6.3%; ICC = 0.88) and test duration (CV = 6.7%; ICC = 0.89). There was no significant difference between i⩒O_2max(S) and i⩒O_2max(R) (303 ± 40 W vs. 301 ± 42 W) (P <.05). The present results suggest that i⩒O_2max determined directly during a maximal incremental test is repeatable and provides a very good estimate of the minimum exercise intensity that elicits ⩒O_2max.