Objective To evaluate how rating of perceived capacity (RPC) is related to maximal oxygen uptake (VO_2max) and examine VO_2max at onset of training in healthy adults.

Methods In total, 125 newly registered fitness centre members, equally men and women, answered the RPC scale and performed a treadmill test for measurement of VO_2max. Eligible criteria were <4 weeks of fitness centre membership, physically inactive, ≥18 years and not pregnant. The RPC is a one-page scale (1–20) based on metabolic equivalent tasks, where the individual chooses the most strenuous activity that can be sustained for at least 30 min.

Results The Bland-Altman plot demonstrated a tendency of overestimation, meaning that the participants ranked their own aerobic capacity 17.5% higher than objectively measured values of VO_2max. The mean difference between the two methods were +4.92±1.96 and +6.35±1.96 mL/min/kg VO₂ in men and women, respectively. The Pearson correlation coefficient was moderate, with r=0.426 (p<0.01). A linear regression analysis showed that both age and VO_2max were significant predictors of RPC (p<0.01). Measured VO_2max at onset of fitness centre membership was in men aged 38.7±11.7 and women aged 34.7±9.9, 40.5±7.2 and 35.0±6.0 mL/min/kg, respectively. Estimated VO_2max from the RPC scale was 45.7±9.8 and 41.4±10.1 mL/min/kg in men and women, respectively.

Conclusions The RPC seems less accurate at the individual level and may overestimate VO_2max. Still, it may be considered useful in large-scale studies.