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The purpose of this study was to compare V˙O2max, V˙O2-time slopes at the end of the protocol (last 30 s), and the presence of a V˙O2 plateau (V˙O2-time slope < 0.05 L·min−1 during the last 30 s) across four protocol durations (5, 8, 12, and 16 min) during incremental cycling exercise to V˙O2max.Eight male (23.8 ± 3.2 yr) and eight female (26.0 ± 8.9 yr) subjects of moderate to high fitness levels participated in the study.V˙O2max was significantly higher in men than in women for each protocol duration, with main effect means of 4.23 versus 2.84 L·min−1, respectively. For women, V˙O2max did not differ between any protocol duration. For men, V˙O2max for the 8-min protocol (4.44 ± 0.39 L·min−1) was significantly higher than for all other protocol durations. Analysis of covariance, using the highest V˙O2max as the covariate, removed all protocol-duration significance for men. The V˙O2 slope for the final 30 s of each test was significantly lower for the 16-min protocol compared with the 5-min protocol, for both men and women. The ventilation threshold across four protocols was similar, at approximately 76% of V˙O2max for both men and women.The protocol duration of tests to V˙O2max should be between 8 and 10 min for healthy, moderately to highly trained subjects.