Verification Trials Can Create the Illusion of VO _2max in Addition to Contributing to its Confirmation

This study examined whether constant-workload verification trials performed at intensities below, at, and above the ramp-incremental peak power output (PPO) contribute to confirming maximal oxygen uptake (V̇O_2max). Fifteen trained to well-trained male cyclists (V̇O_2max: 63.6 ± 5.6 mL·kg^-1·min^-1) completed maximal ramp testing followed by seven randomized verification trials (80%-110% PPO at 5% intervals) on separate days. Differences in V̇O₂ responses were analyzed using linear mixed-effects models. Effect size was calculated using Hedges' g. The peak V̇O₂ attained during the verification trials was expressed relative to the ramp-derived V̇O_2max and classified as lower (< 95%), within normal variability (95%-105%), or higher (> 105%). The peak V̇O₂ values at 80%, 105%, and 110% PPO were significantly lower than ramp-derived V̇O_2max (p < 0.05), whereas no significant differences were observed at 85%, 90%, and 95% PPO. Effect sizes were small at 85%-95% PPO (Hedges' g = 0.29-0.32), medium at 100%-105% PPO (Hedges' g = 0.63-0.66), and large at 80% and 110% PPO (Hedges' g = 1.21-1.34). Of 105 verification trials, 81 were within ±5% of ramp V̇O_2max, 22 were lower (mainly at 80% and 110% PPO), and two exceeded ramp V̇O_2max (at 85% and 95% PPO). Although verification trials did not meaningfully contribute to the verification of V̇O_2max, trials performed at 85%-95% PPO provided the best chances of confirming V̇O_2max in trained individuals. Interpretation of verification trials relative to ramp-derived PPO is protocol dependent, which may limit generalizability across different ramp designs.