Purpose:
Valid protocols use nomograms based on standardized stages to calculate maximal oxygen uptake (VO₂max). Although the maximal ramp exercise protocol offers advantages over traditional protocols, it is not known if the non-standardized stages approach affects the accuracy to estimate VO₂max. The study aims to examine the accuracy of 2 equations for predicting VO₂max in a maximal ramp exercise test.

Methods:
Overall, 11 men (age: 26 ± 5 years, height: 178 ± 7 cm, weight: 77.6 ± 9.9 kg) underwent 3 sessions of a maximal ramp test on a motorized treadmill; the speed increments were equal but with 0, 3, and 6% grades. Expired gases were analysed with a portable metabolic system. The VO₂max measured was set as the highest mean value observed from 7 consecutive breaths and it was predicted from 2 equations: American College Sports Medicine (ACSM) and Myers.

Results:
VO₂max predicted by ACSM equation (54.3 ± 6.7 mL • kg^–1 • min^–1) was approximately 10 ± 10% higher and by Myers equation (30.6 ± 6.1 mL • kg^–1 • min^–1) approximately 38 ± 11% lower than directly measured (49.6 ± 6.7 mL • kg^–1 • min^–1, p < 0.05). Bland-Altman graphs indicate low and no agreement for ACSM and Myers equations, respectively. The calculated standard error of the estimates was 6.5 mL • kg^–1 • min^–1 for ACSM equation and 19.9 mL • kg^–1 • min^–1 for Myers equation.

Conclusions:
The ACSM and Myers equations significantly over- and under-predict the VO₂max of young adults, respectively. Although the former overestimated VO₂max, we recommend its use with caution.